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The present invention relates to engines, and more particularly to internal combustion engines employing one or more pistons and cylinders, as can be employed in vehicles as well as in relation to a variety of other applications.
Internal combustion engines are ubiquitous in the modern world and used for numerous applications. Internal combustion engines are the most common type of engine utilized for imparting motion to automobiles, propeller-driven aircraft, boats, and a variety of other types of vehicles, as well as a variety of types of motorized work vehicles ranging from agricultural equipment to lawn mowers to snow blowers. Internal combustion engines also find application in numerous types of devices that are not necessarily mobile including, for example, various types of pumping mechanisms, power washing systems, and electric generators.
Many different types of internal combustion engines have been designed and built over the years. Among the most common such engines are engines in which one or more pistons are mounted within one or more corresponding cylinders arranged about a crankshaft, where the pistons are coupled to the crankshaft by way of one or more connecting rods such that linear movement of the pistons is converted into rotational movement of the crankshaft. In terms of automotive engines, typically such crankshaft-based engines are four-stroke engines in which each engine piston repeatedly moves through a series of four strokes (cycles), namely, a series of intake, compression, combustion and exhaust strokes.
Although such conventional, crankshaft-based four stroke engines are popular and are undergoing continuing improvement, such engines nevertheless suffer from several limitations. First, the fuel efficiencies that can be achieved by such engines continue to limited, something which is disadvantageous particularly insofar as the world's supply of fossil fuels is limited, insofar as demand (and consequently price) for fossil fuels continues to increase, and insofar as concerns over the impact of fossil fuel-based internal combustion engines upon the global environment continue to grow. The fuel efficiencies of such engines are limited for a variety of reasons including, for example, the weight of such engines, and frequent operation of such engines in an idling manner when no load power is truly required (e.g., when an automobile is at a stop light). A further factor that limits the fuel efficiencies of many such engines that employ spark plugs in combination with high octane fuels (rather than diesel engines) is that such engines, in order to avoid undesirable pre-ignition combustion events during the compression strokes of such engines, are restricted to designs with relatively modest (e.g., 9-to-1 or 10-to-1) compression ratios.
Second, because combustion strokes in such engines only occur during one of every four movements of a given piston, such engines by their nature require that an external input force/torque be applied to impart initial rotational momentum to the crankshaft of the engine in order for the engine to attain a steady state of operation in which the engine (and its crankshaft) is naturally able to advance to successive positions at which combustion events can take place. For this reasons, such engines typically employ an electrically-driven starter motor that initially drives the engine until the engine is able to attain its own steady state of operation. Relatedly, to maintain such steady state rotational operation, and also to reduce the degree to which output torque provided by the engine varies as combustion events occur and then pass, such engines typically require a flywheel that tends to maintain the rotational momentum of the engine at a constant level.
Although such starter and flywheel components employed in conventional crankshaft-based four stroke internal combustion engines are commonly used, and well-understood in terms of their operation, the inclusion of such devices within such engines adds complexity and/or significant weight (as does a crankshaft) to the engine that, consequently, can increase the cost of designing or building the engine, increase the complexity of maintaining or repairing the engine, and/or further reduce the fuel-efficiency of the engine. Further, depending upon how effective the starter of the engine is in terms of starting the engine, the need for a starter can further be an impediment to effective (and enjoyable) operation of the engine. For example, it can be particularly frustrating to an operator when a starter mechanism fails or otherwise is incapable of starting an automobile engine in a short amount of time, particularly when the operating environment is cold such as during wintertime.
Various other types of internal combustion engines likewise suffer from various limitations that may be the same, similar to, or different from the limitations described above. For example, while many of the above-described crankshaft-based 4 stroke internal combustion engines are able to run fairly cleanly in terms of their engine exhaust emissions, in contrast many diesel engines as well as conventional crankshaft-based 2 stroke engines under at least some operating circumstances are unable to effectively combust all of the fuel that is delivered into the cylinders of those engines and consequently emit fairly high levels of undesirable exhaust emissions. This is problematic particularly as there continues to be increasing concern over environmental pollution, and various governmental entities are continuing to enact legislation and regulations tending to require that such engine exhaust emissions be restricted to various levels. Such crankshaft-based engines also still require starters and flywheel mechanisms to allow for starting and proper operation of the engines.
Further in relation to the above-discussed issues, it should additionally be appreciated that crankshaft engines typically (notwithstanding the presence of a flywheel, etc.) will not run below five-hundred (500) rotations per minute (RPM) and will not produce useable torque much below one-thousand (1000) RPM. It is largely for this reason that transmissions for crankshaft engines, whether they are of the gear-type or of the infinitely-variable type, typically have a low gear that is used as the default gear. In the absence of the presence and use of such a low gear, such crankshaft engines would typically kill (cease to operate) whenever the vehicle being powered attempted to take off from a stopped position, since the load of the vehicle would be too much for the engine to bear.
That said, given the typical presence of such transmissions in such crankshaft engines, facilitating operator control of such transmissions remains a concern. Particularly with respect to crankshaft engines that use infinitely variable transmissions, the vast majority use one lever for the control of the engine and another lever for the control of the swashplate of the transmission, where adjustment of the swashplate changes the effective gear ratio provided by the transmission. During operation of an engine, control of the transmission typically first involves moving of the engine lever, from the idle position to that of full throttle, and then subsequently involves moving of the swashplate lever away from its initial (neutral) position so as to cause the apparatus (the vehicle being powered) to start moving. As the swashplate lever is initially moved off of its neutral position, the transmission is in its lowest gear. Then, as the swashplate lever is moved progressively farther from the neutral position, the transmission correspondingly proceeds to higher and higher gear ratios, such that the apparatus (vehicle) moves progressively faster.
Although the above-described system and method for controlling the operation of an infinitely variable transmission is implemented in a number of conventional work vehicles that employ such transmissions (e.g., certain farm equipment), this system and method is not well-suited for implementation in general-use automobiles or commercial vehicles, since most people are generally used to systems and methods for controlling the operation of such vehicles that are simpler (e.g., an accelerator pedal in combination an automatic transmission having a drive setting that automatically controls the transmission gear ratio under most operational circumstances). Further, most people are generally unfamiliar with (and would therefore be uncomfortable with) manipulating two controls of the above-described types, in a continuous manner both with respect to controlling the engine throttle and also with respect to controlling the gear ratio, in order to control the speed of a vehicle.
For at least one or more of these reasons, it would be advantageous if an improved internal combustion engine could be developed that did not suffer from one or more of the above-described limitations to as great a degree and/or provided one or more advantages relative to conventional engines.
The present inventor has recognized the desirability of an improved internal combustion engine. In U.S. Pat. No. 8,135,534 issued on Mar. 13, 2012 and entitled “Hydraulic Engine”, the contents of which are hereby incorporated by reference herein, the prevent inventor disclosed a new hydraulic engine design that is advantageous by comparison with many conventional engines in one or more manners. That said, in view of one or more considerations including those discussed above, the present inventor has recognized that additional improvements to the hydraulic engine design of the aforementioned patent and/or to other internal combustion engines can be made, and thus engines having (or operating in conjunction with) one or more such improvements are described and encompassed by the present disclosure.
More particularly, in at least some of embodiments encompassed by the present disclosure, an infinitely-variable, continuously-variable, partly-continuously-variable, or similar transmission device is employed as part of, or in conjunction with, an engine. In at least some such embodiments, the transmission device is a variable-displacement hydrostatic drive motor and is employed in conjunction with, or as part of, a hydraulic engine such as that disclosed in the aforementioned patent. Further, in at least some such embodiments, a processing device employed by the hydraulic engine enables simplified operator control of the engine, including the variable-displacement hydrostatic drive motor, so as to achieve a desired vehicle speed determined based upon an accelerator pedal position, without ongoing continual control being needed from the operator in terms of controlling the effective gear ratio of the drive motor that is appropriate for attaining the desired velocity.
Additionally, in at least some additional embodiments encompassed by the present disclosure, there is provided one or more of: (a) one or more active check valves governing hydraulic fluid flow into or out of one or more of the hydraulic chambers of engine cylinders; (b) a free-wheeling section allowing for hydraulic fluid exiting a load associated with the hydraulic engine (e.g., a hydraulic wheel motor or variable-displacement hydrostatic drive motor) to proceed back to a link by which the hydraulic fluid is being driven by the engine to the motor; or (c) a perforated cone fuel atomizer associated with at least one intake valve. Further, in at least some further embodiments, a hydraulic engine can employ parallel-connected pairs of hydraulic cylinders, or other arrangements of pairs of hydraulic cylinders. Additionally, although in some embodiments one or more of the features disclosed herein are implemented as part of, or in conjunction with, hydraulic engines, in additional embodiments encompassed herein one or more of the features can be implemented as part of or in conjunction with other types of internal combustion engines, such as crankshaft-driven internal combustion engines.
More particularly, in at least one example embodiment, the present disclosure relates to an internal combustion engine. The engine includes a plurality of cylinders with a plurality of pistons and a plurality of combustion chambers therewithin, where combustion events occurring with the combustion chambers cause the pistons to experience movement. The engine further includes a transmission device having an output shaft, where an output rotational characteristic of the output shaft is related to an input quantity associated with an input power received at the transmission device by an effective gear ratio of the transmission device, and where the effective gear ratio is determined based at least in part upon a first control signal and can take on substantially any value within a substantially continuous range of values. The engine additionally includes at least one coupling mechanism by which an output power associated with movement of the pistons is at least indirectly converted into the input power, and a first sensing device configured to sense an actual output velocity and to output a first signal indicative thereof, where the actual output velocity either is or is substantially directly related to the output rotational velocity of the output shaft. The engine also includes a second sensing device configured to sense a position of an operator-actuatable input device and to output a second signal indicative thereof, and at least one controller coupled at least indirectly to each of the transmission device, the first sensing device, and the second sensing device, and configured to determine a difference between the actual output velocity as indicated by the first signal and a desired output velocity indicated by the second signal, and to output the first control signal for receipt by the transmission device based at least in part upon the difference.
Additionally, in at least one further example embodiment, the present disclosure relates to an internal combustion engine. The engine includes a first cylinder and a first piston within the first cylinder, where a first combustion chamber and a first hydraulic chamber are formed within the first cylinder. The engine further includes a second cylinder and a second piston within the second cylinder, wherein a second combustion chamber and a second hydraulic chamber are formed within the second cylinder, where the second piston is coupled to the first piston by way of a connector tube in a back-to-back manner such that enlargement of the first combustion chamber in response to a combustion event therewithin causes corresponding enlargement of the second hydraulic chamber and reductions in sizes of the first hydraulic chamber and the second combustion chamber. The engine also includes one or more active check valves coupled to the first cylinder and the second cylinder and governing at least in part whether hydraulic fluid can enter or exit the first or second hydraulic chambers, and a source of compressed air, wherein the source is external of the first cylinder and is coupled to the cylinder by way of a first intake valve. The first and second pistons do not ever operate so as to compress within the first and second cylinders an amount of uncombusted fuel/air mixture, and an intake valve head associated with the first intake valve includes associated therewith a perforated cone fuel atomizer.
Further, in at least one additional example embodiment, the present invention relates to a method in an internal combustion engine. The method includes detecting an accelerator pedal position indicative of a desired velocity and providing a first signal corresponding to the accelerator pedal position, and detecting an indication of an actual velocity and providing a second signal indicative of the actual velocity. The method also includes determining, by way of at least one processing device, a velocity difference based at least indirectly upon the first and second signals. The method further includes, based upon the determined velocity difference, generating at least one first control signal by way of the at least one processing device, and sending the at least one first control signal to a transmission device associated with the engine. The method also includes, further based upon the determined velocity difference, at a first time, sending or refraining from sending at least one second control signal to at least one engine component so as to cause combustion events within the engine to cease, whereby at least one operation of the engine including the transmission device is adjusted so as cause a magnitude of the velocity difference to be adjusted toward zero or to remain proximate zero.
Referring to
Turning to
Further as shown, each of the cylinders 10, 12, 14 and 16 includes a respective combustion chamber 22 that interfaces several additional components. More particularly, each of the respective combustion chambers 22 interfaces a respective sparking device 24 that is capable of being controlled to provide sparks to the combustion chamber. Also, each of the respective combustion chambers 22 interfaces both a respective intake valve 26 and a respective exhaust valve 28. Each respective intake valve 26 is further coupled to a respective pressurized induction module 30, which in turn is also coupled to a respective fuel injector 32. As will be described further below, the sparking devices 24, intake and exhaust valves 26 and 28, induction modules 30 and fuel injectors 32 are typically mounted within a head portion of the cylinder. The intake and exhaust valves 26, 28 in the present embodiment are electronically-controlled, pneumatic solenoid valves and can, depending upon the embodiment, more particularly be 3-way, normally-open, solenoid valves or 4-way valves. The components 8-32 can generally be considered to constitute a core or main portion of the engine 4, as represented by a dashed line box 34.
As described further below with respect to
During engine operation, as controlled by the electronic control circuitry 116, the pressurized induction modules 30 receive fuel from their respective fuel injectors 32 (which are located so as to direct fuel into the air induction modules directly behind the intake valves) and also receive pressurized air, as described further below. The fuel injection pulses can vary in their lengths, for example, from about 1-2 ms pulses to up to 25 ms pulses (the fuel injection pulses typically being at a higher pressure than the compressed air pressure). In turn, the respective intake valves 26 associated with the respective pressurized induction module 30 are controlled to allow the resulting fuel/air mixture to proceed into the respective combustion chambers 22 of the respective cylinders 10, 12, 14 and 16. Combustion events occur within the combustion chambers 22, in particular, after such fuel/air mixture has been added to the combustion chambers upon the occurrence of sparks from the respective sparking devices 24 (there is little or no possibility of pre-ignition prior to the sparking events). The combustion events taking place within the combustion chambers 22 cause movements of pistons within the piston cylinders 10, 12, 14 and 16, which in turn (due to the hydraulic/physical links 20) result in hydraulic power being communicated to the motor 18. Subsequent to the occurrences of the combustion events in the respective cylinders 10-16, exhaust gases exit the respective combustion chambers 22 by way of the respective exhaust valves 28, which also are controlled by the electronic control circuitry 116.
Still referring to
The auxiliary power unit 44 includes an auxiliary power unit hydraulic motor/flywheel 46 and a second set of cylinders 48 that includes first and second additional cylinders 50 and 52, respectively. The cylinders 50 and 52 are coupled physically with one another, as well as coupled hydraulically with one another and with the auxiliary power unit hydraulic motor/flywheel 46, as represented figuratively by links 57. As was the case with each of the cylinders of the first set 8, each of the additional cylinders 50 and 52 includes a respective combustion chamber 22 that is in communication with each of a respective sparking device 24, a respective intake valve 26, and a respective exhaust valve 28. Further, each of the respective intake valves 26 of the respective cylinders 50 and 52 is coupled to a respective pressurized induction module 30, which in turn is coupled to a respective fuel injector 32. Again, each of the fuel injectors 32, valves 24, 26 and sparking devices 28 are controlled by the electronic control circuitry 116.
Additionally as shown, the pressurized induction modules 30 associated with each of the cylinders of the first and second sets of cylinders 8, 48 are provided with pressurized air from the air tank 36 by way of links 56. Further, the air powered fuel pump 54 also receives, and is driven by, pressurized air from the air tank 36 by way of the links 56. In response to receiving the pressurized air, the fuel pump 54 in turn supplies pressurized fuel to the fuel injectors 32 of each of the cylinders of the first and second sets of cylinders 8, 48, by way of additional links 58.
Notwithstanding the above description regarding the main air compressor 38 and powering of that compressor, it is envisioned that in alternate embodiments one or more different arrangements can be employed in this regard. For example, in one alternate embodiment, a further power unit identical or similar to the auxiliary power unit 44 (e.g., including a hydraulic cylinder pair module identical or similar to the arrangement of the cylinders 50, 52 and associated components of the auxiliary power unit 44 as discussed further below in relation to
During normal operation of the engine 4, compression events occur within the cylinders 50, 52 of the auxiliary power unit 44 and, as a result, pistons within the cylinders 50, 52 move. Due to the movement of the pistons within the cylinders 50 and 52, hydraulic fluid is communicated through, and thereby causes rotation of, the auxiliary power unit hydraulic motor/flywheel 46, which in turn operates the air compressor 38 and thus generates pressurized air within the air tank 36. The pressurized air is communicated to the air powered fuel pump 54 (again, as indicated above, in other embodiments, a fuel pump that is battery driven or hydraulically driven can also be used) as well as to each of the pressurized induction modules 30 associated with each of the cylinders of the first and second sets 8, 48 by way of the links 56, allowing for combustion events to occur within each of those cylinders. Additionally, even when the auxiliary power unit 44 is not experiencing combustion events, pressurized air can still (occasionally when appropriate) be generated within the air tank 36 and thus communicated to the pressurized induction modules 30 and air powered fuel pump 54, due to the operation of the electric air compressor 40 and the battery 42.
As indicated by the links 20 and 57 discussed above, the cylinders of the first and second sets 8, 48 within the engine 4 are hydraulically coupled to the motor 18 and the auxiliary power unit hydraulic motor/flywheel 46, respectively. Thus, in contrast to many conventional internal combustion engines, the engine 4 employs cylinders (and pistons therewithin) not to provide rotational torque to a crankshaft that in turn provides rotational output power, but rather to move hydraulic fluid through the links 20, 57 to the motor 18 and the auxiliary power unit hydraulic motor/flywheel 46 so as to generate rotational output power. That is, the flow of the hydraulic fluid causes rotational movement (and thus vehicle movement). Flow of the hydraulic fluid also is accompanied by pressure, where the amount of pressure is typically a function of the resistance to the flow by the load (the flow of hydraulic fluid provided by the engine is somewhat analogous to current provided by a current generator in an electric circuit, while the pressure resulting from the flow is analogous to a voltage that is created due to the resistance to that current flow arising from the load). Insofar as the pistons within the cylinders of the first and second sets 8, 48 are not tied to any crankshaft, those pistons can be considered “free pistons” having sliding motion that is not constrained by any such crankshaft.
Additionally, as will be described in further detail below with respect to
Further with respect to the manner in which fuel and air is provided into the combustion chambers 22, it should be mentioned that it is generally desirable to maintain a substantially (or entirely) constant fuel-to-air ratio in the combustion chambers at all engine speeds (e.g., a 14.7 to 1 ratio of fuel to air by weight). Because electronically-controlled, pneumatic solenoid valves (or, alternatively, electrically-controlled hydraulic solenoid valves) are used to actuate the intake valves 26, it can be assumed that varying the duration of the intake valve pulse (in conjunction with varying the duration of the fuel injection pulse) would be a method for controlling the induction process. Such a method can be achieved through the use of intake valves that are 4-way, two position solenoid valves.
While such an implementation can be employed in some embodiments, through testing, it has been determined that it often is difficult to linearly control the induction when actuating the above-described solenoid valves in such a manner. More particularly, in testing it has been determined that the solenoid valves often take approximately 9 ms to begin to actuate, but if the valves are actuated for 12 ms or longer, the maximum charge of air will be swept into the combustion chamber. That is, due to the use of pressurized air from the air tank 36, air enters the combustion chambers 22 rapidly when the intake valves 26 are opened and, when the intake valves begin to open, the fuel/air mixture enters with such force and speed that it can sometimes be difficult to regulate the amount of the fuel/air mixture (and particularly the amount of air) that enters the combustion chamber.
As an alternative, through testing it has been found that the use of 4-way valves can allow for more positive control if controlled in a particular manner. The extra output port available in a 4-way valve can be used to pressurize a rear intake plunger chamber of the valve when the solenoid is energized, such that the vent hole used to vent that chamber can be (and must be) eliminated. When the solenoid is de-energized, the chamber is vented through the internal porting of the 4-way valve itself. Using such a valve, it has further been demonstrated that, in order to better regulate the amount of air (and fuel) entering the combustion chamber via such a valve, the intake valve should be actuated to open for a predetermined constant length of time (e.g., 12 ms) and to regulate the amount of air by varying the pressure of the induction air. The amount of fuel that is injected can still be controlled by varying the duration of the fuel injector pulse.
Although some embodiments of the present invention envision the use of a pressurized air supply such as the air tank 36 having a constant pressure (for example, at 150 to 175 psi), in other embodiments, regulation of the pressure of the induction air can be attained by varying the pressure at the air tank 36. In such embodiments, the pressure within the air tank 36 can be varied by controlling the main air compressor 38 (or the electric air compressor 40) in real time based upon various criteria, such as the degree to which an operator has depressed an accelerator pedal (as shown in
Turning to
Further as shown, the first and second cylinders 10, 12 are arranged in an opposed manner such that the first piston connector tube 66 extends between the respective pistons 62 of the cylinders, the hydraulic chambers 64 of the respective cylinders are each positioned inwardly of the respective pistons within the cylinders along the connector tube, and the combustion chambers 22 of the respective cylinders are each positioned outwardly of the respective pistons within the cylinders. Likewise, the first and second cylinders 14, 16 are arranged in an opposed manner such that the second piston connector tube 68 extends between the respective pistons 62 of the cylinders, such that the hydraulic chambers 64 of the respective cylinders are each positioned inwardly of the respective pistons within the cylinders along the connector tube, and such that the combustion chambers 22 of the respective cylinders are each positioned outwardly of the respective pistons within the cylinders.
Given this arrangement, movement of the pistons 62 of the first and second cylinders 10, 12 are coordinated with one another, and the movements of the pistons of the third and fourth cylinders 14, 16 are coordinated with one another. However, because the cylinders 10 and 12 are oriented in the opposed, back-to-back manner, movement of the connector tube 66 with the pistons 62 of those cylinders in one direction tends to reduce the size (volume) of the combustion chamber 22 of one of the cylinders while expanding the combustion chamber of the other of those two cylinders, and movement of the connector tube and those pistons in the opposite direction tends to have the opposite effects on the respective combustion chambers of those cylinders. Likewise, movement of the connector tube 68 along with the pistons 62 of the third and fourth cylinders 14, 16 in one direction tends to reduce the size of one of the combustion chambers 22 of one of those cylinders while expanding the size of the other of the combustion chambers of those cylinders, while movement of the connector tube and those pistons in the opposite direction tends to have the opposite effects on the respective combustion chambers of those cylinders. It should further be noted that, when the combustion chambers 22 are expanding due to combustion events within those chambers, those chambers can be thought of as expansion chambers due to the adiabatic expansions that are occurring therein. In contrast, when the combustion chambers 22 are contracting (e.g., in response to combustion events that are occurring within others of the combustion chambers), those chambers can be thought as exhaust chambers, since at such times the exhaust valves 28 associated with those chambers are opened to allow the contents of those chambers to exit those chambers.
Additionally, as the connector tube 66 and its respective pair of pistons 62 move in a given direction so as to affect the sizes (volumes) of the combustion chambers of the cylinders 10 and 12, complementary changes in the sizes (volumes) of the respective hydraulic chambers 64 of those cylinders also occur. For example, as the connector tube 66 and its pistons 62 move in one direction, this tends to reduce the size of the hydraulic chamber 64 of one of the cylinders that is also experiencing an increase in the size of its combustion chamber 22, and tends to increase the size of the hydraulic chamber of the other of the cylinders that is simultaneously experiencing a reduction in the size of its combustion chamber. Likewise, as the connector tube 68 and its respective pair of pistons 62 move in a given direction so as to affect the sizes of the combustion chambers of the cylinders 14 and 16, complementary changes in the sizes of the respective hydraulic chambers 64 of those cylinders also occur.
For example, in the present view shown in
Actuation of the various cylinders 10-16 causes back and forth movement of the connector tubes 66 and 68 and their respective pistons 62 in the directions represented by the arrows 71 and 73. In the present embodiment, it is generally preferred that, for engine balancing purposes, the connector tube 66 and its corresponding pistons 62 be operated to move in a manner that is consistently the opposite of the movements of the connector tube 68 and its corresponding pistons 62, and vice-versa. That is, when the connector tube 66 and its corresponding pistons 62 are actuated to move along the direction indicated by the arrow 71, the connector tube 68 and its pistons are actuated to move in the direction indicated by the arrow 73, and vice-versa. However, in alternate embodiments, such opposite, balanced movements of the pistons 62 and connector tubes 66, 68 associated with the two pairs of cylinders 10, 12 and 14, 16 need not occur, and rather the respective connector tubes and their corresponding pistons can move entirely independently of one another (indeed, it is possible for the engine 4 to operate even when the pistons 62 of only one of the pairs of cylinders 10, 12 and 14, 16 are moving).
As indicated above, the links 20 of
In addition to the check valves 72 and 74, respectively, the respective hydraulic chambers 64 of the respective first and second cylinders 10 and 12 are also coupled to third and fourth check valves 76 and 78, respectively, which in turn are coupled to one another and also coupled to a link 80. The check valves 76 and 78 are respectively orientated to allow hydraulic fluid flow out of the respective hydraulic chambers 64 of the first and second cylinders 10 and 12, respectively, to the link 80, but not to allow backflow into those hydraulic chambers from that link. Further, fifth and sixth check valves 82 and 84, respectively, additionally couple the link 80 to the hydraulic chambers 64 of the third and fourth cylinders 14 and 16, respectively. The check valves 82, 84 are orientated to allow hydraulic fluid flow to proceed from the link 80 into the hydraulic chambers 64 of the cylinders 14, 16, but to preclude hydraulic fluid flow from those chambers back to that link.
Given the configuration of the check valves 76, 78, 82 and 84 and the link 80, when one of the hydraulic chambers 64 of the first and second cylinders 10 and 12 contracts, fluid flow proceeds from that contracting chamber by way of its respective one of the check valves 76, 78 through the link 80 to the check valves 82 and 84, by which the fluid is in turn able to enter the hydraulic chambers 64 of the third and fourth cylinders 14, 16. Typically, hydraulic fluid tends to flow into one (rather than both) of the hydraulic chambers 64 of a given pair of cylinders of a cylinder assembly that is expanding due to movement of the pistons 62 within those cylinders. It is additionally possible for hydraulic fluid to pass, via the check valves 72, 74, 76, 78, 82 and 84, from the reservoir 70 into the hydraulic chambers 64 of the cylinders 14, 16 even when the pistons 62 within the cylinders 10, 12 are not moving.
Finally, seventh and eighth check valves 86 and 88, respectively, are additionally coupled between the hydraulic chambers 64 of the third and fourth cylinders 14 and 16, respectively, and a link 90. The seventh and eighth check valves 86, 88 are both orientated to allow outflow of hydraulic fluid from the hydraulic chambers 64 of the cylinders 14, 16 to the link 90, and to preclude backflow from that link into those chambers. The link 90 as shown further couples the check valves 86, 88 to the hydraulic wheel motor 18a, which in turn is coupled back to the hydraulic reservoir 70 by way of a link 92. Thus, hydraulic fluid flowing out of the hydraulic chambers 64 of the cylinders 14, 16 is directed to and powers the hydraulic wheel motor 18a and, after passing through that motor, then returns to the hydraulic reservoir 70.
Given the presently-described arrangement of the cylinders 10-16, pistons 62, connector tubes 66, 68, check valves 72-78 and 82-88, and links 80 and 90-94, the movement of one or both of the coupled pairs of pistons within the pairs of cylinders 10, 12 and 14, 16 causes hydraulic fluid flow to occur from the reservoir 70 through one or both of the hydraulic chambers 64 of one or both of the cylinders 10, 12 (the lower pressure pair of cylinders), then subsequently through one or both of the hydraulic chambers of the third and fourth cylinders 14, 16 (the higher pressure pair of cylinders) and ultimately to the hydraulic wheel motor 18a, which then directs the hydraulic fluid back to the reservoir 70. During normal operation, when both the pistons 62 and connector tube 66 of the cylinders 10, 12 and the pistons and connector tube 68 of the cylinders 14, 16 are experiencing movement, hydraulic fluid in particular flows from the reservoir 70 through that one of the hydraulic chambers 64 of the cylinders 10, 12 that is expanding, then through that one of the hydraulic chambers of the cylinders 14, 16 that is expanding, and then to the hydraulic wheel motor 18a (and further back to the reservoir). Hydraulic fluid flow through the hydraulic chambers 64 of the cylinders occurs regardless of the particular motion of the pistons 62 and connector tubes 66, 68. That is, any movement tending to contract any one or more of the hydraulic chambers 64 tends to force hydraulic fluid to move through the system, even if the movement only relates to the pistons 62 and connector tube 66 or 68 of one of the pairs of cylinders 10, 12 and 14, 16.
In addition, simultaneous movements involving both of the connector tubes 66, 68 and all of the pistons 62 of all of the cylinders 10-16 tend to be additive. That is, equal movements occurring with respect to both of the pairs of cylinders 10, 12 and 14, 16 tend to produce double the effective hydraulic fluid pressure available to the hydraulic wheel motor 18a as would otherwise occur with movement occurring with respect to only one of the pairs of cylinders (doubling of the hydraulic fluid pressure particularly occurs with respect to the embodiment of
Although a schematic diagram similar to that of
Additionally, since the auxiliary power unit 44 includes only the two cylinders 50, 52, the auxiliary power unit only includes four check valves. First and second of the four check valves correspond to the check valves 72 and 74 of
In alternate embodiments, neither the main portion 34 of the engine 4 nor the engine's auxiliary power unit 44 need have the particular numbers of cylinders and pistons shown in
Although it is possible that in some alternate embodiments there will be one or more cylinders with pistons that are not coupled respectively to oppositely-orientated pistons (e.g., by way of connector tube(s)), such embodiments are not preferred. By employing oppositely-orientated, coupled pairs of pistons as described above, movement of a given piston due to a combustion event can be readily controlled and limited by actuation of (e.g., by causing a combustion event at) the other, oppositely-orientated piston that is coupled to the given piston, or at least controlled and limited by the physical confines of the cylinders and other associated components, some of which are described further below in more detail with respect to
While
As described above and further shown in
Further as shown in
Notwithstanding the particular embodiment of
When combustion events occur within the combustion chambers 22 of the cylinders 10, 12 shown in
Rather, in the present embodiment, the connector tube 66 is fitted with a pair of connector tube collars 134, where one of the connector tube collars is positioned along the connector tube 66 within each of the respective cylinders 10 and 12, respectively. Additionally, the main engine housing 102 includes a pair of dashpot assemblies 136 that, as shown, are located on opposite sides of the center bulkhead 104 at the innermost ends of the hydraulic chambers 64, respectively. As will be described in further detail with respect to
Due to the presence of the connector tube collars 134 and the dashpot assemblies 136, movement of the piston assembly 67 typically is restricted not by way of the cylinder heads 112, but rather due to the interfacing of the connector tube collars with the dashpot assemblies (albeit, in some circumstances, movement of the piston assembly 67 can also be limited due to restrictions on the flow of hydraulic fluid out of the hydraulic chambers 64, such as when there are large loads on the engine 4). Entry of each respective connector tube collar 134 into its respective dashpot assembly 136 results in a rapid slowing-down and stopping of movement of the respective connector tube collar toward the center bulkhead 104, and thus results in a rapid slowing-down and stopping of the movement of the piston assembly 67 in that direction. For example, entry of the connector tube collar 134 of the second cylinder 12 into the respective dashpot assembly 136 of that cylinder as shown in
Referring further to
As shown in
The oil seal cover 142, like the capacitor case 138, is a cylindrical/annular structure. However, the oil seal cover 142 has an inner diameter that is less than the inner diameter of the capacitor case 138 and in particular is only about the same as (or slightly greater than) the outer diameter of the connector tube 66, which is narrower than the outer diameter of the connector tube collar 134. Consequently, while movement of the connector tube 66 is not prevented by the oil seal cover 142, the connector tube collar 134 is completely precluded from advancing past the oil seal cover farther toward the center bulkhead 104. Further, because of the relative sizes of the inner diameter of the oil seal cover 142 and the outer diameter of the connector tube 66, and also because of the sealing provided by the oil seal 144, the passage of hydraulic fluid from the hydraulic chamber 64 of the cylinder 12 through the center bulkhead 104 to the opposite cylinder 10 is entirely or at least substantially precluded.
It should be further noted that the particular outer and inner diameters of the connector tube 66 and the oil seal cover 142, respectively, can vary depending upon the embodiment. Also, the connector tube 66 can vary in its diameter along its length. Often it is desirable to have the diameter of the connector tube 66 be fairly large, particularly near the piston 62, such that its diameter is not much less than the outer diameter of the piston. Through the use of such an arrangement, any pressure applied to the surface of the piston 62 facing the combustion chamber 22 during combustion is magnified or leveraged within the corresponding hydraulic chamber 64, since the annular surface of the piston facing the hydraulic chamber 24 is significantly smaller in area than the surface of the piston facing the corresponding combustion chamber 22.
Although the connector tube collar 134 cannot pass beyond the oil seal cover 142, in practice the connector tube collar never (or seldom) reaches the oil seal cover due to the operation of the dashpot assembly 136 in relation to the connector tube collar. More particularly as shown, the capacitor case 138 can be understood as encompassing a first cylindrical portion 146 that is located farther from the center bulkhead 104 and a second cylindrical portion 148 that is located closer to the center bulkhead. Further, the second cylindrical portion 148, as shown, includes one or more (in this case, four) dashpot orifices 150 extending through the wall of the capacitor case 138. The dashpot orifices 150 allow hydraulic fluid to exit the cavity 140 as the connector tube collar 134 moves into the cavity 140 and proceeds toward the oil seal cover 142. While allowing hydraulic fluid to exit from the cavity 140, the dashpot orifices 150 also serve as a restriction on the rate at which the hydraulic fluid is able to exit the cavity, such that there is a natural back pressure applied against the connector tube collar 134 counteracting the pressure that is being exerted by that collar as it proceeds in the direction of the arrow 143 (presumably due to a combustion event). The amount of back pressure applied against the connector tube collar 134 is generally a function of piston speed (the higher the piston velocity, the higher the pressure), and consequently the flow through the dashpot orifices 150 acts as a speed brake.
Often, the restriction upon hydraulic fluid flow provided by the dashpot orifices 150 is sufficient to completely stop movement of the connector tube collar 134 along the direction of the arrow 143 before the collar reaches the dashpot orifices. However, when the piston speed is sufficiently high (e.g., when the force applied to the piston 62 within the cylinder 12 is particularly large), the connector tube collar 134 can proceed far enough into the cavity 140 such that it begins to pass by the dashpot orifices 150 or even completely passes by those orifices. As this occurs, for hydraulic fluid to exit the cavity 140, the hydraulic fluid first flows from the cavity between the outer diameter of the connector tube collar 134 and the inner diameter of the capacitor case 138. The hydraulic fluid flowing within this narrow annular space then can exit either by way of the dashpot orifices 150 or by traveling entirely past the connector tube collar 134. Regardless of the particular flow path(s) that occur, it should be evident that, as the connector tube collar 134 moves partly or entirely over and past the dashpot orifices, significantly increased amounts of resistance to movement toward the oil seal cover 142 are experienced by the connector tube collar. Because of this increased resistance, it is almost never the case that the connector tube collar 134 actually reaches the oil seal cover 142.
Although in the present embodiment hydraulic fluid exiting the capacitor cases 138 by way of the dashpot orifices 150 remains within the cylinders 10, 12, in other embodiments the fluid exiting the dashpot orifices can be directed to other locations. For example, in at least some embodiments, the engine employs the same hydraulic fluid as is located within the cylinders and provided to the hydraulic wheel motor and auxiliary power unit hydraulic motor/flywheel also as coolant for the engine. That is, in some such embodiments, the engine does not employ any radiator or any separate fluid (such as ethylene glycol) to cool the engine, but rather utilizes as coolant the very same hydraulic fluid as is used to transmit power within the engine, and the movement of the pistons within the cylinders powers movement of the coolant through the cooling system. It will be understood that, in such embodiments, the dashpot orifices 150 are the initial segments of cooling channels extending within other portions of the engine body such as the main engine housing 102, cylinder heads 112, and cylindrical sleeves 114 of
As will be described further below with respect to
Further as shown in
Due to the annular insulator 152, an ambient capacitance exists between the capacitor case 138 and the oil seal cover 142, as well as between the capacitor case and the components forming the wall of the cylinder 12 (e.g., the main engine housing 102, cylinder head 112 of that cylinder, and cylindrical sleeve 114 of that cylinder as shown in
Turning to
More particularly with respect to the components mounted upon/within the cylinder head 112,
Also as shown, the intake valve 26 extends through the main induction cavity 700 along an axis 714, and further extends beyond the main induction cavity through the cylinder head 112 via a valve guide/passageway 718 up to an intake plunger chamber 720 (the valve stem being slip-fit within the valve guide/passageway) formed within the cylinder head 112. Similarly, the exhaust valve 28 extends through the exhaust cavity 702 along an axis 716, and further extends beyond the exhaust cavity via a valve guide/passageway 722 up to an exhaust plunger chamber 724 (again with the valve stem being slip-fit within the valve guide/passageway) also formed within the cylinder head 112. A cover 726 of the cylinder head 112 serves as an end portion of the cylinder head and also serves to form end walls of the plunger chambers 720 and 724. In at least some embodiments, the valve guide/passageway 722 has a slightly larger diameter than the valve guide/passageway 718, to allow for greater heat expansion of the exhaust valve stem 706. Although the respective plunger chambers 720 and 724 are substantially sealed from the main induction cavity 700 and exhaust cavity 702, respectively, there can be some small amount of leakage between the respective cavities and chambers by way of the respective valve guides/passageways 718 and 722, respectively. Leakage of air in this manner can serve to cool the valves 26, 28, and generally does not undermine operation of the valves 26, 28.
Located within the respective plunger chambers 720 and 724, respectively, at respective far ends 728 of the intake and exhaust valves 26 and 28, respectively (which are opposite the respective valve heads 704 of those valves), are respective plungers 730 and 732 of those valves. The plungers 730, 732 are generally cylindrical structures having diameters greater than the valve stems 706 of the valves 26, 28. At least certain portions of the respective plungers 730, 732 have outer diameters that are substantially equal to (albeit typically slightly less than) corresponding inner diameters of the respective plunger chambers 720 and 724, respectively. O-rings 734 are fitted into circumferential grooves around the outer circumferences of the plungers 730, 732. Consequently, respective inner portions 736 of the respective plunger chambers 720, 724 are substantially sealed relative to respective outer portions 738 of those plunger chambers by the respective plungers 730, 732 with their O-rings 734. In the present embodiment, the plunger 730 of the intake valve 26 has a larger diameter than the plunger 732 of the exhaust valve 28, although in alternate embodiments the diameters can be the same (or even the plunger 732 can have the larger diameter). It should be mentioned that, although O-rings such as the O-rings 734 can provide a sealing function in some embodiments as discussed above, in alternate embodiments other sealing structures or mechanisms can be employed, such as sleeves made of a non-stick substance such as polytetrafluoroethylene (e.g., TEFLON® polytetrafluoroethylene provided by E. I. du Pont de Nemours and Company of Wilmington, Del.), or a coating on the plungers that is made from such a non-stick substance. Also, in some alternate embodiments, precision-fit components can be sufficient to provide adequate sealing.
In the view provided, the valves 26, 28 are both in closed positions such that the air/fuel mixture within the main induction cavity 700 cannot be delivered to the combustion chamber 22 within the cylinder 12, and such that any exhaust byproducts within the combustion chamber cannot be delivered from that chamber into the exhaust cavity 702. However, actuation of the respective valves 26, 28 causes those valves to open, more particularly, by moving along their axes 714, 716 in a direction indicated by an arrow 740.
In contrast to many conventional engines that employ camshafts and various valve train components, in the present embodiment the opening and closing of the valves 26, 28 is accomplished electronically and pneumatically. More particularly, pressurized air supplied to the main induction cavity 700 is further communicated to input ports 745 of both a first 4-way solenoid-actuated poppet valve 742 and a second 4-way solenoid-actuated poppet valve 744 (electronic control signals being provided to these valves from the electronic control circuitry 116) by way of lines 746. First and second output ports 748 and 750, respectively, of the first poppet valve 742 are coupled by lines 756 to the respective inner portion 736 and outer portion 738 of the intake plunger chamber 720, while first and second output ports 752 and 754, respectively, of the second poppet valve 744 are coupled by others of the lines 756 to the respective inner portion 736 and outer portion 738 of the exhaust plunger chamber 724. Based upon the position of the first poppet valve 742, the pressurized air is either supplied to the inner portion 736 or the outer portion 738 of the intake plunger chamber 720 and, complementarily, the outer portion or the inner portion of that plunger chamber is exhausted to the outside environment (by way of an exhaust port 755). Likewise, based upon the position of the second poppet valve 744, the pressurized air is either supplied to the inner portion 736 or the outer portion 738 of the exhaust plunger chamber 724 and, complementarily, the outer portion or the inner portion of that plunger chamber is exhausted to the environment.
Upon actuating the first poppet valve 742 so as to direct the pressurized air to the outer portion 738 of the intake plunger chamber 720, however, the intake valve 26 is moved in the direction of the arrow 740 and forced open. Similarly, upon actuating the second poppet valve 744 so as to direct the pressurized air to the outer chamber 738 of the exhaust plunger chamber 724, the exhaust valve 28 is moved in the direction of the arrow 740 and force open. Actuation of the poppet valves 742, 744 causes the valves 26, 28 to open fast enough (e.g., within 10 ms or less), and leakage through the valve guides/passageways 718, 722 is typically slow enough, that no appreciable changes in the pressures within the inner portions 736 of the plunger chambers 720, 724 due to such leakage occurs through those guides/passageways. The relatively large diameter of the plunger 730 is advantageous insofar as it helps guarantee that the intake valve 26 will open. Further, although not necessarily the case, in the present embodiment the volume occupied by the plunger 732 within the exhaust plunger chamber 724 is relatively large (and larger than the volume occupied by the plunger 730 within the chamber 720) so that relatively little time is required to fill in the outer portion 738 of the chamber 724 with pressurized air, thus leading to a quicker response in the opening of the exhaust valve 28.
Particularly with respect to the intake valve 26, the speed with which the intake valve opens is further enhanced by the influence of the pressurized air within the main induction cavity 700 upon the valve head 704 of the intake valve 26. The speed of air (and fuel) entry is sufficiently great that the process can be termed “pressure wave induction”, and the complete induction process can in some embodiments take less than 10 ms (or even a shorter time when operating the engine at less than full throttle). In at least some embodiments, the fuel injector 32 is energized slightly before the intake valve 26 opens, so that virtually all of the fuel injected for a given combustion stroke of the engine will be swept into the combustion chamber and used during that stroke. The time during which the second poppet valve 744 is actuated, which controls the opening of the exhaust valve 28, is generally longer than the time during which the first poppet valve 742 is actuated, and the timing of the former can be of particular significance in terms of causing appropriately-timed closing of the exhaust valve.
In general, because the induction of fuel/air into the combustion chamber 22 is accomplished electronically and pneumatically, any manner of timed actuation of the valves 26, 28 can be performed. Further, in comparison with some valves that are moved strictly electronically by way of solenoid actuation, the presently-described manner of actuating valves is advantageous in certain regards. In particular, because the valves 26, 28 in the present embodiment are piloted (controlled) electronically by the poppet valves 742, 744 but driven pneumatically as a result of the compressed air, actuation of the valves 26, 28 can be achieved in a manner that is not only rapid and easily controlled, but also requires only relatively low voltages/currents to drive the solenoids of the poppet valves. Additionally it should be further noted that, while actuation of the valves 26, 28 over times on the order of 10 ms is not particularly fast in terms of valve actuation, it is sufficient for the present embodiment of the engine 4. As will be described further below, the present embodiment of the engine is able to provide greater torque that many conventional engines. Because the engine has more torque, it can run slower than a comparable crankshaft-based engine. Further, although the embodiment of
Referring to
In the embodiment of
Further as shown, in the present embodiment, in place of the annular oil seal 144 shown in
By comparison with the EOT sensor/dashpot assembly embodiment shown in
Notwithstanding the embodiment shown in
Turning to
Referring to
In contrast to
In addition to showing various positions of the piston assembly 67,
Given that a pair of each of the components 24-32 and 154 is shown to be implemented with respect to the cylinder assembly 100, and given that a first of each of those pairs of components is associated with the first cylinder 10 toward which the piston assembly 67 moves to attain the left EOT position while a second of each of those pairs of components is associated with the second cylinder 12 toward which the piston assembly moves to attain the right EOT position, henceforth for simplicity of description those first components associated with the first cylinder will be referred to as the respective “left” components of the cylinder assembly while those second components associated with the second cylinder will be referred to as the respective “right” components of the cylinder assembly. It should be noted that, given this convention, the “right” EOT sensor within the second cylinder 12 senses whether the piston assembly 67 has reached the left EOT position, while the “left” EOT sensor within the first cylinder 10 senses whether the piston assembly has reached the right EOT position.
Notwithstanding this convention employed in the present description, it should at the same time be understood that this convention is merely being employed for convenience herein, and that any given embodiment of the present invention need not in particular have pairs of components that are oriented in a leftward or rightward manner with respect to any arbitrary reference point. Indeed, regardless of any particular descriptive language used herein, the present invention is intended to encompass a wide variety of embodiments having components arranged relative to one another and to other reference points in a variety of manners, and not merely the particular arrangements shown herein.
Turning to
Subsequently, at a step 166, the left fuel injector 32 is switched on to begin a pulsing of fuel into the left pressurized induction module 30. Then, at a step 168, the left intake valve 26 is opened and, at a step 170, the fuel/air mixture received by the left pressurized induction module 30 from the left fuel injector 32 and from the air tank 36 (by one of the links 56) is inducted into the left combustion chamber 22 at very high speeds. The timing difference between the time at which the fuel injector 32 begins spraying and the time at which the intake valve physically opens can be approximately 5 to 10 ms, and this delay is advantageous for allowing fuel to enter completely into the combustion chamber; nevertheless, in other embodiments this delay may be negligible or zero. Eventually, at a step 172, the left fuel injector 32 is switched off to stop pulsing fuel into the left pressurized induction module 30 and, at a step 174, the left intake valve 26 is closed. Once this has occurred, the appropriate amount of fuel/air mixture has been provided into the left combustion chamber 22. At this time the left sparking device 24 is fired at a step 176, as a result of which combustion is initiated as represented by a step 178. Once the combustion is initiated, the piston assembly 67 begins to move rightward in the direction of the arrow 145 as shown in
As corresponds to
Eventually, at a step 196, the right fuel injector 32 is switched off and then, at a step 198, the right intake valve 26 is closed. Once this has occurred, the appropriate amount of fuel/air mixture has been provided into the right combustion chamber 22. Then, at a step 199, the right sparking device 24 is fired, thus causing combustion to begin within the right combustion chamber 22 at a step 156. Upon the initiation of combustion, the piston assembly 67 moves leftward as represented by the arrow 143 of
Referring additionally to
Subsequent to the time T1, at a time T2, a left fuel injector graph 210 switches on, corresponding to the initiating of the pulsing of fuel into the left pressurized induction module 30 by the left fuel injector 32. Also at the time T2, a left intake valve graph 212 switches on, indicating that the left intake valve 26 has been opened (or at least is beginning to open) such that the fuel/air mixture within the left pressurized induction module 30 can enter into the left combustion chamber 22. The difference between the times T2 and T1 is further illustrated by a left intake valve delay graph 208, and that difference in the times in particular is set so as to provide sufficient time to allow the left exhaust valve 28 to close (it does not do so instantaneously) prior to the opening of the left intake valve 26. Subsequently, at a time T3, the left fuel injector graph 210 again switches off, corresponding to the cessation of pulsing of the left fuel injector 32. Then, at a time T4, the left intake valve graph 212 also switches low, indicating that the left intake valve 26 has been closed such that no further amounts of fuel/air mixture can proceed into the left combustion chamber 22. Next, at a time T5, a left sparking device graph 214 transitions from a low level to a high level, indicating that the left sparking device 24 has been actuated. A sparking delay graph 216 illustrates the amount of delay time that occurs between the times T4 and T5.
After transitioning high at the time T5, the left sparking device graph 214 remains at a high level until a time T6, at which time it returns to a low level, signifying that the left sparking device 24 has been switched off again. Although actuation of the left sparking device 24 within the time period between the times T5 and T6 can involve a single triggering of that device to produce only a single spark (e.g., at or slightly after the time T5), in alternate embodiments the actuation of the left sparking device can involve repeated (e.g., periodic) triggering of that device to produce multiple sparks within that time period. This can be appropriate in at least some circumstances where the combustion event resulting from a single spark within the left combustion chamber 22 might leave a portion of the fuel/air mixture within the chamber uncombusted, but repeated sparks over a period of time better guarantees that all (or substantially all) of the fuel/air mixture within the left combustion chamber 22 has been combusted.
Regardless of the particular manner in which the left sparking device 24 is actuated, due to the sparking activity, combustion occurs within the left combustion chamber 22 and, as a result, the piston assembly 67 is moving to the right along the direction of the arrow 145 as shown in
At the time T11, the left dashpot assembly 136 receives the left connector tube collar 134 to a sufficient degree that the left EOT sensor 154 produces a signal indicative of a capacitance that has increased above a threshold level. Thus, at this time, a right EOT position graph 218 transitions from a low level to a high level. Upon this occurring, also at the time T11, the left exhaust valve graph 204 immediately is transitioned from a low level to a high level and the right exhaust valve graph 206 is transitioned from a high level to a low level, such that the left exhaust valve 28 is caused to open and the right exhaust valve is caused to close. Subsequently, at a time T12 (which occurs after the time T11 by an amount of time sufficient to allow the right exhaust valve to close, as shown by the intake valve delay graph 208), a right fuel injector graph 220 switches from a low level to a high level, indicating that the right fuel injector 32 begins the pulsing of fuel into the right pressurized induction module 30. Also at this time, a right intake valve graph 222 transitions from a low level to a high level, such that the fuel/air mixture within the right pressurized induction module 30 can enter the right combustion chamber 22 of the cylinder assembly 100.
Similar to the discussion regarding the left fuel injector and left intake valve graphs 210 and 212, respectively, the right fuel injector graph 220 is subsequently switched off at a time T13 and the right intake valve graph 222 is switched off at a time T14. Subsequently, at a time T15, which occurs subsequent to the time T14 by an amount indicated by the sparking delay graph 216, a right sparking device graph 224 is switched high and then switched low again at a time T16, and thus the right sparking device 24 is switched on between those times. Due to the actuation of the right sparking device 24 (which again, as described above, can involve the production of only a single spark or, alternatively, multiple sparks), combustion occurs within the right combustion chamber 22. This in turn causes movement of the piston assembly 67 along the direction indicated by the arrow 143 as shown in
While
Indeed, in some circumstances, it is also possible that neither the left nor the right EOT positions will be attained by the piston assembly 67 even though the piston assembly continues to be moved back and forth within the cylinder assembly 100 as a result of combustion events. Alternatively, in still other circumstances, it is possible that the force imparted to the piston assembly 67 during a given combustion event will be too low even to move that piston assembly 67 out of the EOT position in which it currently resides. In each of these circumstances, the manner of movement experienced by the piston assembly 67 within the cylinder assembly 100 will differ from that shown in
Referring to
Referring particularly to
More particularly, in the present example, when the piston assembly 67 attains the left EOT position at a time T1, the operation initially proceeds in much the same manner as was the case in
In contrast to the operation shown in
Subsequently, at a time T32 (which differs from the time T31 by an amount of time shown by the intake valve delay graph 308), a right fuel injector graph 320 switches from low to high and a right intake valve graph 322 likewise switches from low to high, thus, causing fuel to be injected into the right pressurized induction module 30 by the right fuel injector 32 and causing fuel/air mixture to be provided into the right combustion chamber 22 via the right intake valve 26. Next, at times T33 and T34, respectively, the right fuel injector graph 322 is switched to a low value and likewise the right intake valve graph 322 is switched to a low value, thus shutting off the right fuel injector 32 and then closing the right intake valve 26, respectively. Further, at a time T35 (which occurs subsequent to the time T34 by an amount of time indicated by the sparking delay graph 316), a right sparking device graph 324 switches from low to high, resulting in actuation of the right sparking device 24. This continues until a time T36, at which the right sparking device graph 324 is again switched low. As a result of the actuation of the right sparking device 24, a combustion event within the right combustion chamber 22 occurs, and consequently the piston assembly 67 again returns to the left EOT position at a time T41, at which time the left EOT position graph 302 again rises, the left exhaust valve graph 304 again falls and the right exhaust valve graph 306 again rises. Subsequent to the time T41, the graphs 302-324 all operate in the same manner at respective times T41-T47 as occurred at the times T1-T7, respectively.
Referring next to
More particularly, as shown in
Subsequently, at a time T53 the left fuel injector graph 410 transitions low, indicating the switching off of the left fuel injector 32, and at a time T54 the left intake valve graph 412 also transitions low, indicating closure of the left intake valve 26. Finally, at a time T55, a left sparking device graph 414 transitions high (with the time T55 occurring subsequent to the time T54 by an amount of time shown by a sparking delay graph 416), turning on the left sparking device 24, and then the left sparking device graph 414 transitions low at a time T56, switching off the left sparking device. Thus, from this example, it is apparent that (at least in this embodiment) the actuation of the valves 26 and 28, fuel injector 32 and sparking device 24 subsequent to the time T51 is identical to the manner in which those components are actuated subsequent to the time T1 of
Further as shown, because in the present embodiment the combustion event that results from the actuation of the left sparking device 24 between the times T55 and T56 does not result in movement of the piston assembly 67 all of the way to the right EOT position (and can in some circumstances not produce any movement at all), the time T61 also is not determined based upon the arrival of the piston assembly at such position but rather is determined by the electronic control circuitry 116 as the expiration of a timer relative to the time T55 (or, in alternate embodiments, some other time such as the time T56). Nevertheless, once this time T61 has been determined, the components 24, 26, 28 and 32 of the cylinder assembly 100 are actuated in substantially the same manner as was described above where the piston assembly 67 reached the right EOT position. That is, at the time T61, the left exhaust valve graph 404 switches from a low level to a high level and the right exhaust valve graph 406 switches from a high level to a low level, thus opening the left exhaust valve 28 and closing the right exhaust valve.
Subsequently, at a time T62, (which occurs subsequent to the time T61 by an amount of time shown by the intake delay graph 408), a right fuel injector graph 420 is switched from low to high and also a right intake valve graph 422 is switched from low to high, thus causing the right fuel injector 32 to inject fuel into the right pressurized induction module 30 and causing the right intake valve 26 to be opened, respectively. Subsequently, at a time T65, the right fuel injector graph 420 switches off, thus stopping the pulsing of the right fuel injector 32, and then later at a time T64, the right intake valve graph 422 is shut off, thus closing the right intake valve 26. Finally, at times T65 and T66 (where the time T65 follows by the time T64 by an amount of time indicated by the sparking delay graph 416), the right sparking device graph 424 switches on and then subsequently switches off, corresponding to the switching on and off of the right sparking device 24. This actuation of the right sparking device 24 again produces a combustion event that tends to cause movement of the piston assembly 67 in the leftward direction (albeit, in some circumstances, little or no movement may actually occur, for example if the vehicle is situated up against an immovable object).
Insofar as
As for
As shown in
Because the piston assembly 67 never leaves the left EOT position as a result of the combustion event that occurs beginning at the time T5, no switching of the left EOT position graph 502 occurs at any time T7, but rather at a time T81 the electronic control circuitry 116 determines that a time has expired and causes further actuation of the components of 24, 26, 28 and 32 of the cylinder assembly 100. In particular, beginning at the time T81, the actions taken at the times T1-T6 described above are reperformed at times T81-T86, respectively (aside from the switching of the open/closed status of the exhaust valves 28, which stay in their current positions as indicated by the graphs 504 and 506). Then, since in the present example the piston assembly 67 continues to remain at the left EOT position, at a time T91 the electronic control circuitry again recognizes that the piston assembly has not moved out of the left EOT position and as a result repeats, at times T91-T96, the operations already performed at the times T81-T86, respectively.
Turning to
Further, the electronic control circuitry 116 is coupled to the hydraulic wheel motor 18a (more particularly, to a sensor at that wheel motor), by which the electronic control circuitry is able to determine wheel (and thus vehicle) speed. Although the wheel speed is often of interest, that speed is not necessarily (or typically) the same as engine speed. Since engine speed is also of interest (for example, in determining the timing of the closing of the exhaust valves 28 as will be described further below), the electronic control circuitry 116 further includes certain additional circuitry as shown. In particular, the electronic control circuitry 116 includes an engine speed sensor 678 that measures the rate at which left and right latches 674 and 676 (which can be considered steering or toggling latches) within the electronic control circuitry are switching. As will be described further below with respect to
Additionally as shown, the electronic control circuitry 116 is coupled to each of the air tank 36, the main compressor 38, the auxiliary compressor 40 and the battery 42, or more particularly, to sensors located at those devices, such that the electronic control circuitry is able to receive sensory signals indicative of the air pressure within the air tank 36, the operational status of the compressors 38 and 40, and the charging, voltage or other electrical status of the battery 42. Further, the electronic control circuitry 116 is coupled to numerous controllable devices and monitorable devices within the main portion 34 of the engine 4, as well as within the auxiliary power unit 44. More particularly as shown, the electronic control circuitry 116 is coupled to each of the respective sparking devices 24, intake valves 26, exhaust valves 28, and fuel injectors 32 associated with each of the cylinders 10-16 and 50, 52 of the main portion 34 of the engine 4 and the auxiliary power unit 44. Also, the electronic control circuitry 116 is coupled to each of the electrodes/EOT sensors 154 associated with the respective dashpot assemblies 136 within each of those cylinders. Notwithstanding
Referring to
As shown in
Nevertheless, if the air pressure within the air tank 36 is determined to be too low at the step 604, then the electronic control circuitry 116 activates either the electric air compressor 40 or the main air compressor 38 (in which case the auxiliary power unit 44 is also activated), at a step 606. More particularly, if the air pressure within the air tank 36 is insufficient to allow proper operation of the auxiliary power unit 44 and the main air compressor 38, then the electric air compressor 40 is switched on (typically for a small air tank this will only take a few seconds). However, if the air pressure within the air tank 36 is sufficient to allow proper operation of the auxiliary power unit 44, or once the air pressure within the air tank becomes sufficient to allow such operation of the auxiliary power unit (e.g., after preliminary operation by the electric air compressor 40), then the auxiliary power unit and the main air compressor 38 become operational until the air tank 36 reaches the desired operational pressure (this can take, for example, about 4-10 seconds). Once either of the compressors 40 and 38 is operational, the system returns to the step 604. However, the electronic control circuitry 116 continues to cycle back and forth between the steps 604 and 606 until such time as the air pressure is sufficiently high within the air tank 36. Typically, by the time that the air pressure within the air tank 36 is high enough for proper operation of the main portion 34 of the engine 4, the auxiliary power unit 44 is also operating.
Next, at a step 608, the electronic control circuitry 116 detects whether the accelerator pedal 670 has been depressed or otherwise a signal has been provided indicating that the engine should be activated. If the answer is no, then the system remains at step 608, and the main portion 34 does not yet begin operation (that is, no combustion events occur yet). If the answer is yes, then the system next proceeds to a step 610. At the step 610, the electronic control circuitry 116 determines based upon one or more signals received from the EOT sensors 154 whether a given piston assembly (such as the piston assembly 67 described above) is positioned at one of the left or right EOT positions associated with its respective cylinder assembly, or alternatively is not at any EOT position. As shown, if it is determined by the electronic control circuitry 116 that the piston assembly is located at a left EOT position or is at neither of the EOT positions, then the electronic control circuitry proceeds to a step 612. Otherwise, if it is determined that the piston assembly is at the right EOT position, then the electronic control circuitry 116 proceeds to a step 642. In alternate embodiments, if neither EOT position is achieved, instead of proceeding to the step 612, the electronic control circuitry can instead proceed to the step 642.
Further as shown, upon arriving at the step 612, the electronic control circuitry 116 sets (e.g., switches “on”) the left latch 674 and resets (e.g., switches “off”) the right latch 676, which as mentioned above are switches that are part of the electronic control circuitry 116 (see
Assuming that the electronic control circuitry 116 has proceeded to the step 612, as shown in
After the delay associated with the step 621 has passed, the electronic control circuitry 116 then proceeds to steps 622 and 623, at which it provides a left fuel injector signal and also activates a left fuel injector pulse timer, respectively. Simultaneously with the steps 622 and 623, the electronic control circuitry 116 also performs steps 624 and 625, at which it provides a left intake valve signal and activates a left intake valve pulse timer, respectively. The performing of the steps 622 and 623 corresponds to the transitioning of the left fuel injector graph 210 at the time T2, along with the continued maintaining of that high level signal until the time T3, as shown in
Upon the completion of the steps 623 and 625 (it will be noted that the step 623 usually completes earlier than the step 625), the electronic control circuitry 116 then proceeds to a step 626, at which it activates a firing delay timer that must be timed out prior to the firing of the left sparking device 24. Activation of the timer in the step 626 corresponds to the delay between times T4 and T5 as shown in the sparking delay graph 216 of
Subsequent to the performance of the steps 629 and 630, several things happen simultaneously. Upon the performance of the step 629 in particular, at a step 632, it is determined whether the piston assembly is no longer positioned at the left EOT position. Simultaneously, upon initiating the timeout timer at the step 630, the electronic control circuitry 116 proceeds to a step 634 at which it continually revisits whether the timeout timer has expired (in at least one embodiment, the timeout timer is set to expire after 500 msec). The step 634 in particular continues to be re-executed until the timeout timer expires, unless the electronic control circuitry 116 at the step 632 determines that the piston assembly is no longer at the left EOT position and further, at a step 661, determines that the piston assembly has reached the right EOT position. To the extent that the timeout timer expires at the step 634 without the conditions of 632 and 661 being met, then the electronic control circuitry 116 proceeds to a step 636, at which the electronic control circuitry effectively makes a new determination of whether the piston assembly is located at either the left or right EOT positions or at neither of those positions, as was originally determined at the step 610.
If at the steps 632 and 661 it is determined that the piston assembly has migrated to the right EOT position, or if at the step 636 it is determined that the piston assembly is at the right EOT position, then the electronic control circuitry proceeds to the step 642. However, if alternatively at the step 636 it is determined that the piston assembly remains at the left EOT position, then the electronic control circuitry 116 proceeds back to the step 612. Also, if at the step 636 it is determined that the piston assembly is currently at neither of the EOT positions, then the electronic control circuitry 116 proceeds to a step 638 at which it determines which of the right or left latches is currently set (as opposed to reset). If the right latch is currently set (and correspondingly the left latch is currently reset), then the system returns to the step 612. Alternatively, if the left latch is currently set (and the right latch is currently reset), then the system proceeds to the step 642 instead.
If the electronic control circuitry 116 arrives at the step 642, either from the step 610 or alternatively from any of the steps 636, 638 or 661, it has arrived there either because the piston assembly 67 is at the right EOT position (as determined at the steps 610, 636 or 661) or alternatively because the piston assembly is in between the EOT positions but the left latch is currently set (as determined at the step 638). As mentioned above, upon arriving at the step 642, the electronic control circuitry 116 sets the right latch 676 and resets the left latch 674, and then proceeds to perform each of steps 644, 646 and 650. As with respect to the step 614, the step 644, which is shown in dashed lines, represents an optional operation that can be performed in some implementations, and is described further below (this step does not correspond to the manner of operation shown in the timing diagrams 8-11). Assuming that the step 644 is not performed, the electronic control circuitry 116 advances from the step 642 to the step 646, at which it provides a control signal to the right exhaust valve 28 causing that valve to close, and to a step 650, at which it provides a control signal to the left exhaust valve causing that valve to open. Upon completion of the step 650, the electronic control circuitry 116 proceeds to a step 651, at which it activates a right intake valve delay timer so as to delay further advancement of the process for an amount of time sufficient to allow the left exhaust valve 28 to close (e.g., with respect to
After the delay associated with the step 651 has passed, the electronic control circuitry 116 then proceeds to steps 652 and 653, at which it provides a right fuel injector signal and also activates a right fuel injector pulse timer, respectively. Simultaneously with the steps 652 and 653, the electronic control circuitry 116 also performs steps 654 and 655, at which it provides a right intake valve signal and activates a right intake valve pulse timer, respectively. The performing of the steps 652 and 653 corresponds to the transitioning of the right fuel injector graph 220 at the time T12, along with the continued maintaining of that high level signal until the time T13, as shown in
Upon the completion of the steps 653 and 655 (it will be noted that the step 653 usually completes earlier than the step 655), the electronic control circuitry 116 then proceeds to a step 656, at which it activates a firing delay timer that must be timed out prior to the firing of the right sparking device 24. Activation of the timer in the step 656 corresponds to the delay between times T14 and T15 as shown in the sparking delay graph 216 of
As was the case subsequent to the performance of the steps 629 and 630 described above, several things also happen simultaneously subsequent to the performance of the steps 659 and 630. Upon the completion of the step 659 in particular, it is determined at a step 660 whether the piston assembly is no longer at the right EOT position. If the piston assembly still is at the right EOT position, the electronic control circuitry 116 remains at the step 660 while, if it has left the right EOT position, then the electronic control circuitry proceeds to a step 640, at which it is determined whether the piston assembly has reached the left EOT position. At the same time, while one or both of the steps 660 and 640 are being performed, the electronic control circuitry 116 also performs the step 634 in which it determines whether the timeout timer has expired.
If the electronic control circuitry 116 determines at the step 634 that the timeout timer has expired prior to determining that the piston assembly has both left the right EOT position at the step 660 and reached the left EOT position as determined at the step 640, then the electronic control circuitry proceeds from the step 634 to the step 636, at which it makes a new determination of the piston assembly position as described above. If, however, the requirements of the steps 660 and 640 are determined by the electronic control circuitry 116 to have been met prior to the expiration of the timeout timer of the step 634, then the electronic control circuitry returns to the step 612. In this manner, then, the electronic control circuitry 116 can cycle back to either the step 612 or the step 642 depending upon whether the piston assembly is determined as being at one of the left or right EOT positions, or in between those EOT positions.
Such engine speed information can be particularly useful in certain embodiments (particularly embodiments differing somewhat from that described above), for example, embodiments in which the steps 614 and 644 mentioned above are performed. More particularly in this regard, it is not always desirable that the exhaust valves 28 be actuated (so as to be closed) immediately upon the piston assembly attaining one of the EOT positions as discussed above. In some circumstances, even though the piston assembly has attained one of the EOT positions (e.g., the left EOT position), it is nevertheless not desirable to immediately close the corresponding exhaust valve (e.g., the left exhaust valve) since such closure of the exhaust valve can prematurely limit the ability of the piston assembly to continue moving in the direction it was traveling (e.g., the left direction) due to pressure changes within its associated combustion chamber. This is particularly the case as the speed of the engine is reduced.
In such circumstances it can be desirable therefore to introduce a delay between the time at which the piston assembly reaches a given EOT position and the time at which the corresponding exhaust valve is closed. Further, it often is desirable that the amount of time delay should take into account engine speed, and particularly that the amount of time delay be increased as the engine speed is decreased, and vice-versa. Assuming this to be the case, therefore, the respective steps 614 and 644 of
Although
Although not shown in
Turning to
As shown, in this embodiment, the hydraulic wheel motor 18a is not directly coupled back to the reservoir 690, but rather is coupled by way of a link 696 to the input terminal of a three-way, two-position proportional hydraulic valve, which can also be referred to as a braking valve 682. Typically the braking valve 682 is operated by way of a single solenoid (which can be controlled by the electronic control circuitry 116 described above), with a spring return, but it also can be pilot-operated. One of two selectable output terminals of the braking valve 682 (opposite the terminal connected to the link 696) is connected to the reservoir 690 by way of a link 684 such that, when the braking valve 682 is in the position shown in
Given the above-described arrangement, hydraulic fluid flow between the links 689 and 694 is prevented when the re-acceleration valve 686 is in a closed position (closed to fluid flow) as shown in
The engine portions 680 represented by the schematic diagram of
However, when a brake is depressed by an operator (again, as sensed by the electronic control circuitry 116), the free-wheeling flow through the hydraulic wheel motor 18a is diverted away from the reservoir 690 and instead sent to the accumulator 692. More particularly, this occurs because the electronic control circuitry 116 actuates the solenoid of the braking valve 682 to move away from the position shown in
Once the brake pedal is released, the braking valve 682 is controlled to return to its normal position in which hydraulic fluid is completely directed back to the reservoir 690. This also occurs if the accumulator 692 becomes filled, as there must be a place for hydraulic fluid to flow in this circumstance. Also, if the hydraulic accumulator 692 becomes completely filled, or if more aggressive braking is desired by the operator than can be achieved by diverting flow to the hydraulic accumulator by way of the regenerative braking system, then the electronic control circuitry 116 can cause normal braking (e.g., by way of brake pads interacting with wheels of the vehicle) or, as discussed in further detail below, can achieve braking by way of operation of a free-wheeling section such as those described below in regards to
When hydraulic fluid/pressure is accumulated within the hydraulic accumulator 692, it is possible to drive the hydraulic wheel motor 18a with such fluid/pressure. In particular, when such pressure exists within the hydraulic accumulator 692, and the accelerator pedal 670 of the vehicle is depressed by the operator, the re-acceleration valve 686 is energized so as to shift from the normal, closed position shown in
It is typically the case that the engine will not be running (e.g., the cylinders 10-16 will not be experiencing combustion events) when the hydraulic wheel motor 18a is being driven by hydraulic fluid from the accumulator 692. Nevertheless, in some circumstances, it is possible that the hydraulic fluid driving the hydraulic wheel motor 18a will be provided to the motor from both the accumulator 692 and from the cylinders 10-16. In any event, once the pressure within the hydraulic accumulator 692 drops to a point where it can no longer sustain desired vehicle acceleration/speed, the engine begins running (again, that is, the cylinders 10-16 experience combustion events) such that hydraulic fluid is supplied to the hydraulic wheel motor by way of the links 90. At this point, the re-acceleration valve 686 is de-energized, and the regenerative braking system is effectively inactivated until the next braking event occurs.
Turning to
More particularly, in the embodiment of the engine portions 800 shown in the diagram of
As active check valves, each of the check valves 872, 874, 876, 878, 882, 884, 886, and 888 is electrically actuatable (e.g., by way of a solenoid or other controllable portion of each valve) to be open or closed, or (in other embodiments) electrically actuatable so that each valve is in condition to be openable if fluid pressure is such causing opening of the valve, or alternatively in condition to be locked closed regardless of the fluid pressure applied thereto. In the present embodiment, electronic control circuitry 816 is connected to each of the active check valves 872, 874, 876, 878, 882, 884, 886, and 888, by way of respective control lines 810, so as to allow the electronic control circuitry to control the opening or closing (or openable state, locked closed state, or other state) each respective check valve. In at least one embodiment, the electronic control circuitry 816 is configured so that, during operation of the hydraulic engine, the active check valves 872, 874, 876, 878, 882, 884, 886, and 888 are configured to be opened or controlled (or openable state, locked closed state, or other state) so that the active check valves allow hydraulic fluid flow to pass through the respective valves at the same or substantially the same times during engine operation as would occur if those check valves were passive check valves.
Aside from providing control signals for this purpose of controlling the active check valves 872, 874, 876, 878, 882, 884, 886, and 888, and providing one or more additional control signals to the free-wheeling section 801 as described in further detail below, the electrical control circuitry 816 can be considered to include all of the other features of the electrical control circuitry 116 discussed above in relation to
Further as shown in
Turning additionally to
By comparison with the embodiment of
As for the embodiment of
Although each of
As already mentioned, further alternate embodiments of the engine 4 such as those shown in FIGS. 15 and 16A-16C, in which the check valves are active check valves (rather than passive check valves) that are controllable, and/or further in which there is a free-wheeling section 801, can allow for additional advantageous operational effects for the engine. The use of the active check valves 872, 874, 876, 878, 882, 884, 886, and 888 particularly allows for enhanced control over whether hydraulic fluid enters or exits the cylinders 10, 12, 14, 16. This can be of particular benefit, for example, when the vehicle 2 is moving with sufficient momentum or moving downhill such that the hydraulic wheel motor 18a can be tending to pump hydraulic fluid back toward the cylinders 10, 12, 14, 16 (e.g., via the reservoir 70) even though the engine is not running (that is, when combustion events in the cylinders 10, 12, 14, 16 are not occurring). By way of the active check valves, even when such pumping of hydraulic fluid into the cylinders can be reduced or eliminated. Further, controlled actuation of the active check valves can allow for better control over the hydraulic fluid flow into and out of the engine cylinders 10, 12, 14, and 16 in manners that enhance the efficiency of the operation of the engine.
Further, the presence of the free-wheeling section 801 can further enhance engine performance. First, both whether the active check valves 872, 874, 876, 878, 882, 884, 886, and 888 are employed or not (e.g., if passive check valves are used), the free-wheeling section 801 can allow for hydraulic fluid being pumped by the hydraulic wheel motor 18a (for reasons discussed above) to proceed in a direction other than directly back toward the cylinders 10, 12, 14, 16, i.e., from the link 92 to the link 90. The extent to which this hydraulic fluid flow occurs through the free-wheeling section can be varied depending upon the embodiment of the free-wheeling section that is employed as well as, in embodiments where one or more aspects of the free-wheeling section are controllable (e.g., in terms of the controlled status of the active check valve 812 or the controlled setting of the needle valve 820 or other valve 830), by controlling those one or more aspect.
Additionally, in the context of regenerative braking, although an accumulator can provide braking, an accumulator can cease to be entirely effective if a maximum capacity is met—that is to say, when the accumulator maximum capacity has been reached during major braking activity of the vehicle and yet braking is intended to continue (e.g., where braking down a long mountain, the maximum capacity of the accumulator can be reached when the vehicle is only part of the way down the mountain, and this can occur relatively quickly). In contrast, through the use of a free-wheeling section such as one or more embodiments of the free-wheeling section 801 of FIGS. 15 and 16A-16C, it is possible to achieve some braking without reaching any maximum (it should be noted that, in at least some further alternate embodiments, an accumulator can be used in combination with the components shown in one or more of FIGS. 15 and 16A-16C). Depending upon the circumstance, desired beneficial operation can be achieved by varying the settings of one or more controllable aspects of the free-wheeling section. For example, in some embodiments, the active check valve 812 can be controlled to allow fluid flow therethrough only at particular times during vehicle operation (e.g., when the vehicle is moving at a fast rate and engine combustion events are not occurring or it is sensed that the vehicle is travelling down a slope and the engine combustion events are not occurring). Also for example, in some embodiments, the effective orifice size provided through the needle valve 820 or other valve 830 can be varied to suit the circumstances. Also, in some further example embodiments, one or more these settings (e.g., active check valve setting or orifice size setting) can be modulated over time. Such modulation can include, for example, setting one or more of these aspects so that hydraulic fluid is entirely precluded at certain times and then changing these settings at other times so that some amount of hydraulic fluid flow is allowed.
Referring to
Also in the present embodiment, the combined area of the holes 853 can determine the net orifice size (the size of the various holes), with it being desired that the combined area be of sufficient size as to avoid creating a delay in filling the combustion chamber when the intake valve opens (e.g., so that filling time is less than 10 ms). Further, the holes 853 can be perforated at an angle other than 90 degrees with respect to the surface of the cone (e.g., canted toward the valve head so as to allow air flow from the valve stem side of the cone to more easily atomize the fuel trapped in and around the holes, as well as to transport the atomized fuel into the combustion chamber when the intake valve opens. A large entrance 851 at the base of the cone leading to the interior 855 is designed to fill most of the circular form of the intake air chamber, which has the effect of forcing the majority of the intake air toward the interior 855, then out through the holes 853, in order to take maximum advantage of the intake air pressure in atomizing the fuel droplets.
Given this arrangement, fuel injected by the fuel injector 32 (see
Although
Further, in some alternate embodiments the fuel atomizer can include an additional heater associated with it that can heat the atomizer cone and further enhance fuel atomization. For example, in one embodiment, a heater is a cylindrical device, with a heater element and a mandrel, that is inserted into the intake portion of the head concentrically with the intake valve. The mandrel can be constructed of a heat-conductive material, such as copper, and can be designed to be mounted in close contact with the valve seat, so as to promote heat transfer from the valvehead to the mandrel. In at least one such embodiment, the mandrel is constructed with a cylindrical groove on a portion of its exterior for placement of the heating element in relation thereto. The heating element can be constructed of a ceramic material with embedded wires or of heater wire with a heat conductive insulator. The wires can be wound circumferentially or in a serpentine fashion, as long as the heated wires have a good heat conductive path to the mandrel while maintaining electrical insulation. One end of the heating element can be connected directly to the mandrel and serve as the electrical return/ground connection, while the other end should be kept insulated. Also, the heater can be fitted with a hole that is located in line with the output spray of the fuel injector, such that the fuel can spray directly into the interior portion of the heater, spreading out on the hot mandrel, as an aid to evaporation/atomization. Typically, the heater would be electrically energized shortly before the vehicle is used, and then kept on for a period of time after the engine has been running, until the mandrel is able to maintain its heated condition using heat from the valve alone.
In still another alternate embodiment, a heater can be constructed that is a combination of the perforated cone heater and the electric heater. In this design, the cone would be affixed as an integral part of the electric heater, typically at the end opposite the valvehead. Using this configuration, the cone would be first heated by the electric heater and then, after the engine was running for a few minutes, be heated by the heat conducted through the valvehead and heater mandrel. Using such a method, no part of the heater assembly would be in direct contact with the intake valve itself.
Additionally, the particular materials used for the perforated cone fuel atomizer 850, size of the holes 853, and other features can be varied depending upon the embodiment. In some cases, dimples in the cone can be utilized in combination with holes. That is, dimples are formed in the outer surface of the cone (toward which fuel is sprayed by the fuel injector), and each dimple in the center of the respective dimple has a respective hole. Presence of such dimples allows a greater amount of the sprayed fuel to be captured proximate the holes such that, when the intake valve is opened and air proceeds through the holes, a greater amount of fuel is atomized. Also, in some cases the shape of the cone can be modified to something other than a cone (e.g., a shape that is more cylindrical than conic, or a shape akin to the end of a trumpet).
Turning to
Notwithstanding these similarities between the arrangement of
The variable-displacement hydrostatic drive motor 18b performs several roles. First, the variable-displacement hydrostatic drive motor 18b converts hydraulic power generated by the engine, which is delivered by the hydraulic fluid flowing (e.g., via a first link 920 discussed further below) from the engine cylinders to the drive motor, into rotational power (e.g., for driving wheels of a vehicle) output by the drive motor, as was also the case with the hydraulic wheel motor 18a discussed in relation to
The magnitude of the effective gear ratio of the variable-displacement hydrostatic drive motor 18b can be controlled and can vary depending upon various factors. More particularly in this regard, the variable-displacement hydrostatic drive motor 18b as shown includes an adjustable swashplate 904 internally within the drive motor, the setting of which is determined by a swashplate control lever 905, and adjustment of the swashplate by way of this control lever allows for adjustment of the effective gear ratio of the variable-displacement hydrostatic drive motor and thus allows for adjustment of the operational setting of the drive motor. Additionally, the operation of the variable-displacement hydrostatic drive motor 18b and particularly the effective gear ratio can also be affected by other factors, such as the input power level (associated with the hydraulic fluid flowing from the engine cylinders), and/or the load directly or indirectly placed on the output shaft 903 (e.g., the vehicle weight).
Given this to be the case, control of the engine with the engine portions 900 involves not only the control capabilities discussed above in relation to
Although not shown in
In addition to the above features, the electrical control circuitry 916 differs from the electrical control circuitry 116 of
In addition to the above-discussed differences between the engine portions 60 of
By contrast, the arrangement of the engine portions 900 shown in
It should further be appreciated that, in the embodiment of
Notwithstanding the above discussion regarding the engine portions 900 of
Also for example, although
Further, it should also be noted in relation to
Now referring to
As already noted, in the process 930 there are two main inputs to the control system, a signal from the accelerator pedal 670 (or from an accelerator pedal position sensor associated therewith that senses the position of the accelerator pedal and outputs the signal indicative of the position thereof) and a signal from the velocity sensor 918. Thus, upon the process 930 starting at a start step 932, the processing device 912 of the electrical control circuitry 916 determines the desired vehicle speed based upon the sensed position of the accelerator pedal 670 at a step 934, and further determines the actual vehicle velocity based upon the signal from the velocity sensor 918 indicating the output shaft 903 rotational speed (although step 936 is shown to occur after the step 934 in this embodiment, the order of these steps can be reversed or these steps can even be considered to be simultaneously occurring in other embodiments). The determined desired and actual velocity values can, depending upon the embodiment, be values that directly correspond to the signal levels received at the processing device 912, or can be derived from those signal levels directly or indirectly based upon various calculations or processing techniques.
Subsequently, at a step 938, the processing device 912 further determines a velocity difference, ΔV, between the desired and actual velocity values determined at the steps 934 and 936, respectively. In some embodiments in which the desired and actual velocity values are respectively simply the received signal values (again, the values of the signals received from the accelerator pedal 670 and the velocity sensor 918, respectively), then this calculation simply involves subtracting the signal provided by the velocity sensor 918 from the signal provided by the accelerator pedal 670 in order to determine the desired velocity minus the actual velocity, which again is the velocity difference ΔV. Once the velocity difference ΔV is determined, then the process advances to a step 940, either directly or indirectly via a step 942 at which the processing device 912 can receive an additional signal from an optional grade sensor or grade switch that is indicative or reflective of a grade/incline on which the vehicle is operating.
Based upon the magnitude and polarity of the velocity difference ΔV calculated at the step 938, as determined at the step 940 the process can the proceed to any of three further steps 944, 946, and 948 as discussed further below. At these subsequent steps, the processing device 912 generates output signals that are provided to the engine, including the engine portions 900, both to adjust the setting of the swashplate 904 in order to adjust the effective gear ratio of the variable-displacement hydrostatic drive motor 18b, and also to adjust the operation of the engine in terms of the combustion events occurring therein (and thus in terms of the driving of hydraulic fluid from the cylinders to the variable-displacement hydrostatic drive motor 18b), so as to achieve the desired speed and acceleration. As already discussed above, adjustment of the operation of the engine in terms of controlling combustion events therein is achieved by the processing device 912 generating and sending control signals (e.g., via the communication links 915 of
More particularly, if at the step 940 it is determined that the velocity difference ΔV is close to zero, e.g., −1<ΔV<2 miles per hour (mph) as shown in the
Alternatively, if upon reaching the step 940 it is determined that the velocity difference ΔV exceeds (or equals) a negative value threshold indicating that the actual velocity of the vehicle exceeds the desired velocity by a significant margin, e.g., ΔV≦−1 mph, then in that case the process advances from the step 940 to the step 946 rather than to the step 944. At the step 946, the processing device 912 sends control signals tending to shut off the engine (or refrains from sending control signals in a manner tending to shut off the engine), that is, so that the engine stops firing altogether and no combustion events are performed. It should be appreciated that, in the present embodiment involving the version of the hydraulic engine 4 corresponding to
Further alternatively, if upon reaching the step 940 it is determined that the velocity difference ΔV exceeds a positive value threshold indicating that the desired velocity of the vehicle exceeds the actual velocity by a significant margin, e.g., ΔV>2 mph, then in that case the process advances from the step 940 to the step 948 rather than to the steps 944 or 946. Upon reaching the step 948, the processing device 912 generates and provides a control signal, via the communication link 917, tending to cause the setting of the swashplate 904 (or the control lever 905 thereof) to be shifted downwards so as to reduce the effective gear ratio. The exact amount of the reduction can vary depending upon the magnitude of the velocity difference ΔV, and depending upon the embodiment. Further, in addition to controlling the swashplate 904 setting in this manner, following the step 948 at a step 950 it is again determined by the processing device whether the amount by which the velocity difference ΔV exceeds the earlier-considered positive value threshold (which in the present example is 2 mph) is within a modest range above that positive value threshold, e.g., 2<ΔV≦6 mph, or if the amount is large, e.g., ΔV>6 mph. If at the step 950 it is determined that the margin is only within the modest range, then the process advances to the step 952 but, if at the step 950 it is determined that the margin is large, then the process instead advances to the step 954.
More particularly, if at the step 950 it is determined that the margin is within the modest range (e.g., 2<ΔV≦6 mph) and the process advances to the step 952, then at the step 952 the processing device 912 generates and sends additional control signals to the fuel injectors 32 of the engine (e.g., by way of appropriate ones of the communication links 915) causing the engine fuel injector pulses to be modulated. Alternatively, instead of (or in addition to) controlling the fuel injectors 32 in this manner, the processing device 912 generates and sends control signals to cause the actual firing of the engine (that is, the firing of the sparking devices 24 creating the combustion events) to be modulated. Regardless of the manner of control over engine operation, in terms of controlling the combustion process and the hydraulic power output by the engine (which determine the hydraulic input power experienced at the variable-displacement hydrostatic drive motor 18b), the processing device 912 performs such control so as to cause the actual velocity to drop down back to the desired velocity, that is, to bring ΔV down to (or toward) zero.
Alternatively, if at the step 950 it is determined that the margin is large (larger than the modest range, e.g., ΔV>6 mph) and the process advances to the step 954, then at the step 954 the processor 912 generates and sends additional control signals so as to run the engine at its maximum level (while simultaneously in accordance with the step 948 the swashplate is shifted downwards in order to put the drive motor into a lower effective gear ratio). The additional control signals generated by the processing device 912 can include control signals provided to the fuel injectors 32, intake valves 26, exhaust valves 28, and sparking devices 24 of the engine that, among other things, increasing/maximizing the frequency of combustion events and the power generated by each combustion event (e.g., by increasing the fuel injected into each cylinder for each combustion event). It should be appreciated that, although for simplicity of explanation the step 948 is shown as preceding each of the steps 950, 952, and 954, it can also be the case in at least some embodiments the swashplate adjustment of the step 948 is performed at the same time as either of the steps 952 and 954 when either of those steps is performed.
It should further be understood that the control operations performed by the processing device 912 in accordance with each of steps 944, 946, 952, and 954 (and 948) does not continue on indefinitely. Rather, although not expressly shown in
In general, the process 930 can continue on indefinitely. Thus, if the velocity difference ΔV is small to begin with (e.g., within the example range −1<ΔV<2), then as long as the determined desired and actual velocities do not change in a manner such that the velocity difference ΔV changes to be significantly greater than zero (e.g., so as to exceed be outside of the example range −1<ΔV<2 and leave that state), then the step 944 continues to be performed, and the process continues generally to cycle around through the step 934, 936, 938, 940, and 944. Likewise, if the velocity difference ΔV is at another particular status (state) corresponding to operation in one of the steps 946, 952, and 954 (e.g., ΔV remains either ≦−1, remains <2 and ≦6, or remains >6), then the process 930 will continue to cycle through the steps 934, 936, 938, and 940, plus either the step 946, the steps 948, 950, and 952, or the steps 948, 950, and 954, as the case may be.
That said, if operation in accordance with one or more of the steps 940, 944, 946, 948, 950, 952, and 954, or other operating circumstances of the engine/vehicle, cause the value of the velocity difference ΔV to change to a different one of the ranges considered at the steps 940 and 950, then the process will shift accordingly. For example, if the processing device 912 performs the step 946 because the velocity difference is in excess of the negative threshold (again, in this example, ΔV≦−1) but as a result of this operation (or for some other reason) the velocity difference ΔV falls back close to zero (e.g., into the −1<ΔV≦2 range), then at this point the process 930 would, upon reaching the step 940 instead proceed to the step 944 rather than the step 946.
Further in regard to the step 942, it should be appreciated that in some embodiments the manner of operation of the processing device 912 in performing control over engine operation in response to the determinations of the velocity difference ΔV (e.g., in the steps 940, 944, 946, 948, 950, 952, and 954) can vary depending upon a grade/incline being experienced by the vehicle (or vary depending upon some other operational circumstance being experienced by the vehicle that can similarly affect loading conditions). In at least some embodiments, the processing device 912 particularly will adapt its control over the swashplate 904 in response to signals from a grade sensor. For example, in some such embodiments, the maximum swashplate setting to which the swashplate is set by the processing device 912 in the steps 944 and 946 will be altered depending upon grade sensor signals. Also, with respect to a grade switch, such a switch can itself determine such a maximum swashplate setting based upon grade/incline information (e.g., as provided by a grade sensor) and either provide such information to the processing device 912 for use by the processing device, or in other embodiments can be provided to the swashplate control lever 905 (or other control mechanism for the swashplate) such that, when the processing device 912 commands that control lever to take on a maximum value, the actual maximum value attained will be in accordance with the grade switch output.
So as to further illustrate example operation of the embodiment of the engine 4 having the engine portions 900 of
More particularly with respect to
Turning to
As for
Among other things,
Notwithstanding the particular example values, and relationships shown in the graphs of
For example in this regard, the amount of swashplate movement off of its highest position typically is a characteristic that can be tailored to the particular size and weight of the vehicle that is equipped. Further for example, a delivery vehicle would likely require more swashplate movement off its highest position for the same ΔV than what a specific sized automobile would require, due to its greater mass. Thus, given a particular vehicle, engine, and hydrostatic drive combination, it typically will be appropriate for the designer/manufacturer of such a vehicle to do testing to determine the most appropriate correlations between ΔV and the proper amount of swashplate movement, and then adjust the process or control algorithm (e.g., adjust the process shown in
It should further be appreciated that the process 930 particularly achieves control, at least in part (e.g., in the step 946), sometimes by completely ceasing engine firing (ceasing combustion events) and then recommencing firing operation of the engine (beginning engine firing or combustion events again) when appropriate. Although operation of such a process is particularly well-suited for a hydraulic engine, which has no starter and can begin running whenever the accelerator pedal is depressed (similar to an electric vehicle), it would be difficult to implement such operation in many crankshaft engines.
Example Advantages of Various Embodiments of Engines Disclosed Herein
Embodiments of engines disclosed herein can be advantageous by comparison with many conventional engines (for example, by comparison with many conventional four-stroke engines) in any one or more of a variety of manners. For example, at least some embodiments of engines disclosed herein are fully capable of commencing operation, and continuing operation, without any starter (e.g., a battery driven electrical motor) or any flywheel (or other device for maintaining momentum). Conventional engines that employ a crankshaft driven by one or more pistons typically require a starter because the force derived from any given combustion stroke(s) of any given piston(s) is insufficient to rotate the crankshaft and move its associated piston(s) sufficiently far that the position(s) of those piston(s) are appropriate for additional combustion stroke(s) to occur. Rather, during the starting process, before or after one or more combustion stroke(s) have occurred, the engine components can shift to a “dead” position in which it is not yet appropriate for any further combustion stroke(s) to occur. The existence of such dead positions particularly occurs because, in between successive combustion strokes, it is necessary to perform compression strokes that both take time and sap rotational momentum from the system. Because of the existence of these dead positions, it is necessary for an outside force (e.g., the starter) to further move the engine components beyond these positions to different positions in which it is appropriate for further combustion stroke(s) to occur
In contrast, at least some embodiments of engines disclosed herein employ pairs of aligned, oppositely-directed pistons and, in such embodiments, the engines receive compressed air from the air tank rather than perform any compression strokes to generate compressed air, and thus these engines and their piston assemblies never move to or become stuck at dead positions. Rather, because at any time a new supply of compressed air (and fuel) can be provided to any given combustion chamber without the performance of any compression stroke, it is always possible to cause another combustion event to occur with respect to a given piston assembly, no matter what the position of the piston assembly happens to be. Additionally, with respect to such embodiments of engines employing pairs of aligned, oppositely-directed positions, every combustion stroke tends to drive the piston assembly directly toward a position at which it is appropriate to cause a combustion stroke directed in the opposite direction. That is, operation of the engine naturally drives the piston assemblies in such a manner that, after any given combustion stroke, the piston assembly is reset to a position that is appropriate for another combustion stroke to take place. At the same time, even if a given combustion event in a given combustion chamber of a cylinder assembly fails to drive the piston assembly sufficiently far so as to move the piston assembly to a position where it is appropriate for the next combustion event to be performed in the other combustion chamber of the cylinder assembly (e.g., the piston assembly remains at a given EOT position as shown in
Given these considerations, no starter (e.g., electric starter, pneumatic starter, hydraulic starter, hand crank starter or other starting means or structure for performing a starting function) is required by at least some embodiments of engines disclosed herein in order to allow the engine to begin operating, that is, no starter is required by these embodiments to allow combustion events within the engine to begin occurring and continue occurring in a sustainable or steady-state manner (or to initially power the engine). Regardless of whether or when the last combustion event in the engine has occurred, or how long the engine has been “off”, the engine is always ready to begin performing combustion events in response to an operator signal (e.g., depressing of an accelerator) or otherwise. Operation of the engine is always either in an “on” state where combustion events are occurring (with high levels of force/torque), or in an “off” state where combustion events are not occurring, but never in a “start” state where a separate, starter mechanism is helping to drive the engine so that it can attain a steady “on” state of operation. Thus, the engine can be repeatedly turned on and off, and can continue to advance to successive positions at which combustion events can occur, without any involvement by any starter.
It should further be mentioned that, because no starter is required in such embodiments of engines, such embodiments of engines are capable of operating or running (that is, experiencing successive combustion events) at a variety of speeds, and in particular are capable of running at very low speeds (including at zero speed and near-zero speeds) that would be unstable for many conventional four stroke and two stroke crankshaft-based engines. Further, in embodiments in which regenerative braking is employed (such as that described in
Additionally, at least some embodiments of engines encompassed by the present disclosure have no need for a flywheel (something which can go hand-in-hand with the additional attribute that at least some embodiments of engines disclosed herein have no need for a starter). In conventional engines involving a crankshaft, whether those engines are four stroke or two stroke engines, it is typically necessary to employ a flywheel so that sufficient rotational momentum of the crankshaft can be maintained to overcome the resistive force that is generated within the engines after a given combustion event has occurred and the piston(s) of the engine are only serving to compress and/or exhaust contents within their combustion chambers, so as to allow the engine to return to a state at which further combustion event(s) can occur. By comparison, at least some embodiments of engines disclosed herein employ pairs of aligned, oppositely-directed pistons, and such engines never face a situation in which further combustion event(s) cannot be performed. Rather, no matter what the position of a given piston assembly, it is always possible to cause an additional combustion event to occur in one (or possibly either) of its associated combustion chambers. Thus, a flywheel need not be present to guarantee that the engine continues to advance to successive positions at which combustion events can occur, and the engine can be repeatedly turned on and off without any involvement by any flywheel (or any starter).
Further, in at least some embodiments encompassed by the present disclosure, the vehicle (or other load driven by the engine) itself can serve as a flywheel due to inertia, and so the vehicle itself can serve to balance or smooth out any variations in torque, pressure and/or volumetric fluid flow that occur as combustion events occur, pass, and then are repeated. Thus, even though no engine flywheel is present in the at least some of the embodiments of engines disclosed herein, nevertheless in such engines noticeable variations in vehicle velocity normally still will not occur due to the alternation of combustion events followed by the absence of such events.
Also, equally if not more significantly, in at least some embodiments encompassed herein, the vehicle movement and associated momentum serves also to provide a phenomenon that can be referred to as “thermodynamic freewheeling” behavior. Such behavior occurs particularly when pistons are able to fully complete their travel down the entire lengths of their cylinder bores during combustion strokes (prior to the exhaust strokes) while continuing to perform net work throughout those movements, which in turn maximizes energy output of the engine (that is, all possible heat energy from each combustion stroke is squeezed out of the engine and available for performing work). Due to the “thermodynamic freewheeling” behavior provided by the engine, fuel efficiency is further enhanced. It should further be noted that inclusion of an accumulator (or other source of backpressure) within the hydraulic circuit formed from the engine's hydraulic cylinders, hydraulic wheel motor (or other load such as the variable-displacement hydrostatic drive motor 18b) and reservoir would tend to negate this benefit (albeit use of an accumulator as described above in connection with regenerative braking, where the accumulator is separate from the hydraulic circuit formed from the engine cylinders, wheel motor (or other load such as the variable-displacement hydrostatic drive motor 18b) and reservoir, does not entail this same difficulty).
Additionally for example, relative to many conventional engines, at least some embodiments of engines disclosed herein are advantageous given their arrangement of aligned, oppositely-directed pistons that are operated in a 2 stroke manner in terms of the amount of torque that can be generated by these embodiments. In a conventional 4 stroke engine employing a crankshaft, force and corresponding torque are generated by a given piston only once every four times it moves. In contrast, at least some embodiments of engine disclosed herein employ pistons 62 that, given their 2 stroke manner of operation, generate force and corresponding torque once every two times the piston moves. Further, because each of the pistons 62 of a given piston assembly such as the piston assembly 67 is linked to and aligned with a complementary, oppositely-directed piston, each piston assembly generates force and corresponding torque with every single movement of that piston assembly.
Also for example, at least some embodiments of engines encompassed in the present disclosure that produce torque by way of hydraulic fluid movement have enhanced torque generating capability relative to engines with crankshafts. In this regard, engines with crankshafts are only able to achieve varying levels of torque as the angles of the connecting rods linking the pistons of such engines with the crankpins of the crankshaft vary. By contrast, engines that produce torque by way of hydraulic fluid movement have an enhanced torque generating capability insofar as those engines do not experience any such torque variation (associated with variation in connecting rod angles) since movements of the pistons are converted into rotational movement by way of hydraulic fluid rather than by way of any mechanical linkages. Further, while engines with crankshafts are often unable to achieve significant or desired levels of torque immediately when combustion events occur due to the particular angular positioning of the connecting rods (e.g., when a piston is at a “top dead center” position), at least some of the embodiments of engines disclosed herein that produce torque by way of hydraulic fluid movement are always immediately capable of generating full (100%) torque upon the occurrence of a combustion event since the force resulting from the combustion event is equally able to be converted into torque by way of hydraulic fluid movement regardless of piston position. Indeed, for all of these reasons, it is envisioned that certain embodiments of engines disclosed herein may be able to output two times or even three (or more) times the overall net torque generated by a comparable-weight 4 stroke crankshaft-based internal combustion engine.
Further, given that such hydraulic engines are able to provide 100% torque at zero speed and given that this torque output is high (and indeed can be more than three times the torque of a comparable crankshaft engine), beneficial synergies can particularly be achieved in at least some embodiments disclosed herein that employ transmission or drive device(s) that are infinitely (or continuously) variable in terms of the effective gear ratio provided thereby, such as the variable-displacement hydrostatic drive motor described above. In at least some of these embodiments, the combination of such a hydraulic engine with such a transmission or drive-device provides for the possibility of controlling the powertrain in such a way that the default position of the transmission or drive device can be an effective high gear, rather than an effective low gear (in contrast to many conventional powertrains, particularly many powertrains employed in relation to crankshaft-driven engines).
One beneficial synergy that can result from this combination is significantly improved fuel efficiency or (in the context of propelling a vehicle) significantly enhanced mileage (e.g., miles per gallon or kilometers per liter of gas or other fuel), since the transmission or drive device (again, for example, the variable-displacement hydrostatic drive motor) can stay in high gear, or at least a higher gear, much more of the time than is possible with many conventional crankshaft engines. Indeed, even with the assumption that a variable-displacement hydrostatic drive motor is somewhat less efficient than a gear-type transmission (e.g., perhaps 7% less efficient), it is still believed that the additional fuel efficiency arising from use of the variable-displacement hydrostatic drive motor in combination with a hydraulic engine, as controlled in accordance with a control process such as that discussed above in relation to
It should be understood from the above that at least some embodiments of engines encompassed herein do employ infinitely-variable, continuously-variable, or partly-continuously-variable transmission or drive device(s) such as a variable-displacement hydrostatic wheel (or drive) motor, and that any of a variety of such transmission devices are intended to be encompassed herein. That said, it should also be noted that at least some other embodiments of engines encompassed herein not only are capable of generating superior levels of torque but also are able to drive the wheels of a vehicle (or other load) directly as shown in
In addition to generating superior levels of torque, at least some embodiments of engines of the present disclosure, particularly the hydraulic engines that do not perform any compression strokes, are able to operate at a significantly higher level of efficiency than many four-cycle crankshaft-type internal combustion engines. One reason for this is that at least some embodiments of the hydraulic engines disclosed herein are able to achieve a significantly higher expansion ratio than many conventional engines, where the expansion ratio is understood as the ratio of the largest, expanded volume of the combustion chambers of the engine cylinders (e.g., at a “bottom dead center” position at the end of the combustion stroke), to the smallest, reduced volume of those combustion chambers (e.g., at a “top dead center” position just prior to combustion). More particularly, in many conventional 4 stroke, crankshaft-driven engines, the expansion ratio is somewhat limited (e.g., to a factor of 9 or 10) due to the geometry of the engine cylinders, crankshaft, pistons, and connecting rods linking those pistons to the crankshaft, which produce a risk of pre-ignition with high compression ratios.
In contrast, at least some embodiments of engines disclosed herein can attain a higher expansion ratio (e.g., a factor greater than 14, for example, a factor of 21 or even higher), and thus attain higher fuel efficiencies (e.g., about 17% to 21% higher fuel efficiencies) for that reason. The configuration of these embodiments of engines entails a reduced (or even zero or approaching zero) risk of pre-ignition, such that it is not necessary to always utilize high octane fuel, and rather it is possible to utilize a relatively lower grade, lower octane (e.g., 80 octane, or even as little as zero octane) fuel. That is, because of the particular piston arrangement in such engines, and particularly because the engines do not require any compression strokes involving the compression of fuel/air mixtures that could involve spontaneous pre-ignition, greater expansion ratios and correspondent fuel efficiency improvements are possible.
It should be further noted the term “expansion ratio” is particularly used herein, particularly in relation to at least some of the embodiments of engines disclosed herein that are hydraulic engines in which no compression strokes are performed (in which compressed air is supplied from the air tank instead). That said, it is recognized that, for many internal combustion engines in which compression strokes occur, the term “compression ratio” is often used synonymously relative to the term “expansion ratio”. Thus, for purposes of comparing the operational characteristics of some engines disclosed herein that are hydraulic engines in which no compression strokes are performed with other engines that do perform compression strokes, it is appropriate to compare the expansion ratios of such hydraulic engines with either the expansion or compression ratios of such other engines.
Relatedly, with respect to at least some of the engines encompassed herein that are hydraulic engines which compress air externally (not by way of any compression strokes in the engine cylinders), it should further be appreciated that, due to such external compression, the adiabatic heat of compression can be partially removed prior to induction, which can be referred to as “intercooling”. Such intercooling has the effect of increasing the thermodynamic efficiency of the engine compared to that of many conventional internal combustion engines, in which the heat of compression cannot be removed.
More particularly in this regard, when a four-cycle crankshaft-type internal combustion engine goes through its cycles of intake, compression, combustion and exhaust, during the compression stroke the pressure that exists immediately after compression is greater than the pressure that would exist if the compression was performed in an isothermal manner. In other words, because the compression stroke in such engines is adiabatic, the self-heating of the gaseous mix causes a further increase in pressure. This has a negative impact on thermodynamic efficiency. In contrast, with respect to at least some embodiments of hydraulic engines in accordance with the present disclosure, these engines compress the air external to the main combustion chamber such that the air has a chance to expand inside a tank prior to being used for combustion. This has a cooling effect on the air, and makes the hydraulic engines even more efficient, compared to four-cycle crankshaft-type internal combustion engines in which compression strokes take place in the cylinders.
From a theoretical perspective, such an enhanced efficiency by such hydraulic engines relative to four-cycle crankshaft-type internal combustion engines can be understood also as follows. Generally speaking, it will be appreciated that the thermodynamic efficiency of an engine corresponds to the ratio of the area inside the temperature entropy curve pertaining to the engine, divided by the area inside the curve plus the area below the curve (e.g., between the curve and an x-axis below it, where the curve is displayed on a Cartesian coordinate system with x/horizontal and y/vertical axes). In this regard, four-cycle crankshaft-type internal combustion engines can be said to have a higher (lifted or elevated) curve in which the area under the curve is significant. By comparison, at least some of the hydraulic engines encompassed herein, which have no compression strokes, have a lower curve in which the area under the curve is smaller. This being the case, the denominator of the above-mentioned thermodynamic efficiency ratio is generally larger for many four-cycle crankshaft engines than it is for many comparable hydraulic engines, and thus the thermodynamic efficiency is generally lower for such crankshaft engines than it is for many comparable hydraulic engines.
In view of this, it should be understood that these hydraulic engines therefore provide not merely one but several related types of efficiency increases relative to four-cycle crankshaft-type internal combustion engines in which compression strokes take place, namely, increased efficiency due to the higher expansion ratios, increased efficiency due to the hydraulic engines' ability to fire at top-dead-center (which crankshaft-type engines cannot effectively do), and increased efficiency due to the intercooling effect.
Further, at least some embodiments of engines in accordance with the present disclosure provide greater fuel efficiency than many conventional engines for one or more additional reasons, in addition to (or instead of) their greater expansion ratios, ability to fire at top-dead-center, and the intercooling effect. First at least some of the engines disclosed herein, and particularly at least some of the hydraulic engines disclosed herein in which no compression strokes occur, have minimal or even zero throttling losses, something which is not the case with typical conventional crankshaft engines. Further, as already discussed above, at least some embodiments of engines disclosed herein do not (or do not need to) employ any crankshaft or connecting rods, camshafts or associated components (e.g., timing chains), or conventional valve train components, and also can be implemented without any transmissions, differential gears, running gears, or other components that are often employed to enhance torque output. Also, at least some embodiments of engines disclosed herein need not have any starter and/or flywheel. Given the absence of one or more of these components, at least some embodiments of engines disclosed herein can be significantly lighter in weight relative to conventional engines that employ such components, and consequently can be more fuel efficient for this reason.
Further, because in at least some embodiments disclosed herein the engines can be turned on and off repeatedly without any involvement by any starter and/or flywheel, the engines need not remain running when output power is not needed (e.g., when a vehicle within which the engine is operating is stopped at a stop light or while coasting). Also, because compression strokes are not ever performed within the piston cylinders, no corresponding loss of rotational momentum and energy occurs as a result of such strokes.
Additionally, with respect to at least some of the embodiments of engines disclosed herein that can begin operation (begin performing repeated combustion events) without any starter, and that can therefore start and stop operation immediately at will without any significant delay, it should be additionally appreciated that such engines also are capable of delivering torque even in the absence of any movement (e.g., at zero speed), similar to the behavior of an electric vehicle (e.g., a golf cart). When a vehicle implementing such an engine is at a standstill or is coasting, the engine need not be on or operational at all (that is, no combustion events need be taking place). Consequently, at least some of the embodiments of engines disclosed herein need not operate in any low or idling mode where combustion events are occurring even though the power generated as a result of those combustion events is wasted. Thus, such engine embodiments can save all of the energy that is otherwise wasted during idling operation by many conventional engines during standstill or coasting operation of the vehicle, which can be significant (e.g., a 20% energy savings). Further, as described above, at least some embodiments of engines disclosed herein can also employ regenerative braking techniques, which further can save on energy that otherwise would be wasted when the vehicle is braked in a conventional manner with brake pads.
It should further be noted that at least some embodiments of engines disclosed herein further are advantageous relative to electric cars and hybrid vehicles (that employ both internal combustion engines and electric power systems). Although (as discussed above) at least some embodiments of engines disclosed herein share certain operational characteristics with electric cars, at least some of these embodiments do not require the same battery power levels that are required by such cars, and consequently do not have the weight associated with the batteries used to provide such battery power. Further, while at least some embodiments of engines disclosed herein are capable of operating in a regenerative manner, which helps to conserve power, unlike conventional hybrid vehicles these embodiments do not require two complicated power systems (e.g., involving both an internal combustion engine and a complicated electric system including an electric motor). Thus, such embodiments of the present invention are less complicated than hybrid vehicles.
Further Comments Regarding Engine Embodiments Encompassed Herein
Notwithstanding the above description, the present invention is intended to encompass numerous other embodiments that employ one or more of the features and/or techniques described herein, and/or employ one or more features and/or techniques that differ from those described above. To begin, although at least some of the embodiments of engines disclosed herein are hydraulic engines in which linear power provided by the pistons in the engine cylinders is converted into rotational power at a motor by way of hydraulic fluid, at least some other embodiments of engines disclosed herein are crankshaft-driven engines having one or more features as discussed above. For example, in at least some embodiments encompassed herein, a transmission control algorithm as discussed above can be employed to control a transmission employed in relation to a crankshaft-driven engine.
Further for example, although at last some of the above-described embodiments of engines envision the use of conventional hydraulic fluid such as oil within the hydraulic chambers 64 of the cylinders and other engine components, in alternate embodiments other fluids can be utilized. For example, in some embodiments, water and/or a water-based compound can be used as the hydraulic fluid within the engine. Also, while at least some of the above-described engine embodiments generate rotational power by driving hydraulic fluid through a hydraulic wheel motor or variable-displacement hydrostatic drive motor (e.g., a motor that generates rotational output), in alternate embodiments it would be possible to generate linear output power. Additionally, while at least some of the above-described engine embodiments employ capacitance sensors (e.g., as formed using the dashpot assemblies 136 with their capacitor cases 138, and the connector tube collars 134), in other embodiments other types of position/motion sensors can be employed, such as magnetic sensors, magnetoresistive sensors, optical sensors, inductive proximity sensors and/or other types of proximity sensors.
Additionally, in at least some of the embodiments of engines discussed above in which the engines have cylinder assemblies and piston assemblies in which there are pairs of aligned, oppositely-directed pistons, in alternate embodiments it would be possible to utilize a group of pistons that, though oppositely (or substantially oppositely) directed, were not aligned with one another but rather were staggered in position relative to one another (e.g., the pistons travel along axes that are parallel with, but out of alignment with or offset from, one another). Further, various embodiments of the engine designs disclosed herein can be employed with a variety of vehicles, for example, various two-wheel drive vehicles (with front wheels driven or rear wheels driven), vehicles with limited slip mechanisms, four-wheel drive vehicles, and others. In some embodiments, for example, in a front-wheel drive vehicle, the engine can be implemented in such a manner that no hoses are needed to couple the engine housing to the hydraulic wheel motor (or other load such as the variable-displacement hydrostatic drive motor).
Also, in some embodiments, more than one EOT sensor or other position sensor can be provided in any given cylinder to allow detection of multiple positional locations of the piston/piston assembly, as well as information that can be derived from such sensed location information including, for example, velocity and/or acceleration. Additionally, in some alternate embodiments, two of the four check valves coupled between the two pairs of cylinders (e.g., either the check valves 76 and 78, or the check valves 82 and 84 of
Additionally, notwithstanding the various control processes and algorithms described above, by which control devices such as the various electronic control circuits and processing devices discussed above govern one or more operations of one or more of the engines described, the present disclosure is not intended to be limited to engines that operate in accordance with such processes and algorithms, but rather the present disclosure is also intended to encompass numerous engines that operate in accordance with any of a variety of other processes or algorithms, as well as numerous methods of operating engines in addition to or instead of those discussed above. For example, the present disclosure is also intended to encompass hydraulic engines that are controlled to operate in a “pulsed” mode manner of operation, rather than a continuous mode. Such functionality can provide a more fuel-efficient way of controlling the engine in certain circumstances, such as cruising down the highway at a fixed speed. In at least some embodiments, the hydraulic engine can run either continuously, or run in a “pulse” mode, or both (e.g., at different times depending upon operational circumstances).
Further, while the above-described embodiments envision implementation in vehicles and the like, embodiments of the present inventive engine can also be employed in other devices that require rotational output power or other types of output power and, indeed, can be utilized to drive other energy conversion devices, such as electric generators. Additionally, while various advantages associated with certain embodiments of the present invention are discussed above, the present invention is intended to encompass numerous embodiments that achieve only some (or none) of these advantages, and/or achieve other advantages.
It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.
The present application claims the benefit of U.S. provisional patent application No. 61/736,991 filed on Dec. 13, 2012 and entitled “Hydraulic Engine With Valve Features”, which is hereby incorporated by reference herein.
Number | Date | Country | |
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61736991 | Dec 2012 | US |