Patent Application
20180094577
The present application is generally related to internal combustion engines. More specifically, the present invention relates to a four-stroke engine having a pair of connecting rods, which are offset at an offset angle as measured from the crankshaft, and a camshaft having an offset of one-half of the crankshaft offset angle, and having at least two cylinders that communicate via a common cylinder head.
Internal combustion engines are devices in which reactants (e.g., fuel and an oxidizer) are combusted in a combustion chamber to produce high-pressure gas so as to apply force to another component of the engine. The typical components of an internal combustion engine are well known to those of ordinary skill in the art. These components generally include cylinders, pistons, valves, the cylinder head, the crankshaft, the camshaft, and the engine block.
Combustion of the reactants takes place inside a combustion chamber, which is generally formed by the cylinder heads, cylinders, and the tops of the pistons. In spark ignition engines, a spark is used to ignite the reactants. In compression ignition engines, the heat created by compression ignites the reactants. Regardless of how the reactants are ignited, the resulting combustion produces heat and pressure that act on the moving surfaces of the engine, such as the top of the piston. The pistons are generally attached to a crankshaft via connecting rods, which transfer the motion of the pistons into rotational motion.
Most internal-combustion engines are four-stroke engines. A four-stroke engine is one in which the piston(s) must complete four movements, or strokes, to produce power. This is also known as the “Otto” cycle. Typically, a four-stroke engine works as follows. During the first stroke, intake, the piston descends, drawing the reactants into the combustion chamber through an inlet valve. The piston continues downward until it reaches the point at which it is farthest from the cylinder head, i.e., bottom dead center. At the start of the second stroke, compression, the inlet valve closes, and the piston moves upward to the point where it is closest to the cylinder head, i.e., top dead center. In the third stroke, power, the compressed reactants are ignited, forcing the piston downward. An outlet valve opens and the piston moves back upward to complete the last stroke, exhaust. The four-stroke cycle is then repeated.
A commonly cited problem with the four-stroke engine is that it operates at only one-third efficiency. In other words, only a third of the potential fuel energy is delivered to the crankshaft. Two thirds of the energy is lost either through the exhaust or as waste heat. Thus, due in part to increased fuel-efficiency standards, numerous variations have been introduced to improve engine efficiency. See U.S. Pat. Nos. 8,434,305, 8,347,850, 7,810,459, 6,543,225, 4,776,306, 4,099,489, 3,871,337, 2,988,065, 2,058,705, 1,790,534, and 608,845; WO Pubs. 2005068812, 2004027237; EP Pubs 1,148,219, 1,170,478, 1,312,778, 1,607,594, 1,895,138, 2,088,283; and David Scott, “Paired-Cylinder Engine,” Popular Science February 1978. Each and every reference cited herein is hereby incorporated by reference in its entirety, where appropriate, for teachings of additional or alternative details, features, and/or technical background.
One alternative to the traditional four-cycle engine is the split-cycle engine, in which the four strokes are shared between two cylinders. In a split-cycle engine, the intake and compression strokes take place in one cylinder. The compressed reactants are then transferred to a second cylinder, in which the power and exhaust strokes are performed. Transference between the first and second cylinder typically occurs via a crossover chamber, which is closed off via a valve before ignition in the second cylinder. Outside of split-cycle engines, communication of the reactants between two cylinders is uncommon in engine design.
The Scott article, cited above, describes a pair of pistons connected by a recess in the block face, where the pistons perform separate “mixture-induction” and “air-swirl” functions. However, this design causes additional cost and efficiency problems. For example, while the cylinder head is easily replaceable, the block face is not. One advantage of the current invention is that it can be created from existing engines efficiently and inexpensively by modifying the cylinder head and the crankshaft or connecting rods.
Traditionally, ignition is timed so that combustion occurs near the end of the compression stroke, i.e., slightly before top dead center. This is needed because the reactants do not completely burn at the moment that the spark fires. Thus, by advancing the spark before top dead center, combustion actually occurs when the combustion chamber reaches its minimum size. Generally, sparks occurring after top dead center are thought to be counter-productive, producing excess waste. Only a few small engines are designed to ignite after top dead center.
Knocking is another engine complication that occurs when the reactants are unintentionally combusted at the incorrect moment. Knocking can cause severe engine damage. In a spark ignition engine, the reactants are meant to be ignited only via the spark plug at the precise time of ignition. Knocking, or abnormal combustion, occurs when a pocket of the reactants are detonated outside the boundary of the flame front. Knocking can be caused by pre-ignition, when the reactants ignite before the spark plug fires.
The prior-art engines discussed herein are to be considered conventional engines where appropriate.
An embodiment of the invention comprises a new and improved internal combustion engine comprising a cylinder head, a first and second cylinder, a first and second piston, a first and second connecting rod, and a crank shaft, wherein the first and second cylinder communicate via the cylinder head, which remains open at all times, and wherein the second connecting rod is offset from the first connecting rod at an offset angle between about 8 and 12 degrees.
An internal combustion engine comprising: a cylinder head, a first and second cylinder in parallel orientation, a first and second piston disposed within said first and second cylinders, a first and second connecting rod, a crank shaft, a camshaft, a first fuel injector operative to said first cylinder and a second fuel injector operative to said second cylinder, and a first spark plug open to said cylinder head above said first cylinder, and a second spark plug open to said cylinder head above said second cylinder; wherein a cylinder head defines an upper boundary and creates a cylinder head space opening between the first and second cylinder, wherein the cylinder head space remains open to the first and second cylinders at all times; wherein the second connecting rod is offset from the first connecting rod defining the second piston at a trailing offset angle between about 8 and 12 degrees; and wherein the camshaft is defined to be offset at one-half of the trailing angle of the second piston, defined between 4 and 6 degrees; and wherein second fuel injector injects fuel into said second cylinder and wherein said first and second spark plugs ignite after the first piston is at top dead center, thereby forcing the pistons to reciprocate within said first and second cylinders and wherein said first and second pistons maintain said offset angle while said pistons are reciprocating having the second piston trailing the first piston.
A method of modifying a conventional engine comprising the following steps: modifying or replacing a cylinder head to allow for at least two parallel cylinders to have a shared head space, by connecting the cylinders via a cylinder head space disposed of above the top of the cylinders and below the cylinder head; and modifying or replacing at least one crankshaft such that a first and second connecting rod is connected to a first piston and a second piston disposed of in said first and second cylinders, wherein said second connecting rod and said crankshaft defining an offset angle where the second piston is trailing the first piston by about 8 and 12 degrees, and modifying or replacing a camshaft having an offset angle of one-half of the offset of the crankshaft, where the second cylinder is trailing the first cylinder by between 4 and 6 degrees.
A system for modifying a standard engine comprising a replacement head having disposed of openings situated between a pair of cylinders on said standard engine, creating a cylinder head space between said pair of cylinders; and further comprising at least one replacement crankshaft having a first connecting rod to a first piston and a second connecting rod to a second piston, said second connecting rod oriented to be trailing the first by between 8 and 12 degrees, wherein said connecting rods and crankshaft situates said pair of cylinders such that the pistons within said pair of cylinders is defined to have the second piston trailing the first and offset by between about 8 and 12 degrees; and a replacement camshaft, having a trailing offset in the second cylinder, with said offset defined at one-half of the offset of the crankshaft, thus between 4 and 6 degrees.
An internal combustion engine comprising: a first leading cylinder and second trailing cylinder having fluid passage between one another in a head opening, a cylinder head, a first and second piston, a first and second connecting rod, a crankshaft, a camshaft, at least two exhaust valves, at least two intake valves, at least one spark plug, and a fuel injection component; wherein the first and second cylinders communicate via the head opening space defined between the cylinder and the cylinder head; wherein the head opening remains open to the first and second cylinders at all times; wherein the second piston is a trailing piston and offset in the second cylinder by between an 8 and 12 degree crank angle; wherein the camshaft is engaged to the at least two exhaust valves and at least two intake valves, and said camshaft is offset by one-half of the crank angle in the second cylinder; and wherein fuel is provided via the fuel injection component only to the trailing cylinder, between 3500 and 5000 revolutions per minute, when the engine is running.
In a preferred embodiment, the internal combustion engine has an offset angle of the crankshaft is 12 degrees and the offset angle of the camshaft is 6 degrees.
In a preferred embodiment, the internal combustion engine has an offset angle of the crankshaft is 8 degrees and the offset angle of the camshaft is 4 degrees.
In a preferred embodiment, the internal combustion engine has combustion occurring via compression or via ignition combustion.
In a preferred embodiment, the internal combustion engine provides ignition to both the first and second cylinder.
In a preferred embodiment, the internal combustion engine begins ignition when the first (leading) piston is at top dead center. In other embodiments, ignition occurs when the first piston is after top dead center.
In a preferred embodiment, the internal combustion engine wherein the exhaust fuel to air ratio is greater than 17-1 between 3500 and 5000 RPM.
In a preferred embodiment, a method of modifying a conventional engine comprising the following steps: modifying or replacing a cylinder head to allow for at least a first leading cylinder and a second trailing cylinder to communicate by connecting the cylinders via an opening disposed of above the top of the cylinders and below the cylinder head; modifying or replacing a crankshaft of said engine such that at least a connecting rod, connected to said crankshaft, is connected to a first piston in said first leading cylinder, and at least a second trailing piston that is disposed of in said trailing cylinder and is offset from said leading cylinder by an offset angle of between about 8 to about 12 degrees; and modifying or replacing at least one camshaft having an offset of one-half of the offset of the crankshaft, such that the offset corresponds to the second trailing cylinder; and, at least one fuel injector, wherein fuel is disposed of only in said trailing cylinder while the engine is running at between 3500 and 5000 RPM.
In a preferred embodiment, a method of increasing the efficiency of a four-cycle engine comprising: modifying said engine, said engine comprising a first leading cylinder and second trailing cylinder, having fluid passage between one another in a head opening, a cylinder head, a first and second piston, a first and second connecting rod, a crankshaft, a camshaft, at least two exhaust valves, at least two intake valves, at least one spark plug, and a fuel injection component; wherein the first and second cylinder communicate said fluid passage within the head opening space between a top of the cylinder and a bottom of the cylinder head; wherein the head opening remains open to the first and second cylinders at all times; wherein the second piston is a trailing piston and offset in the second cylinder by between 8 and 12 degree crank angle; wherein the camshaft is engaged to the at least two exhaust valves and at least two intake valves, and said camshaft is offset by one-half of the crank angle in the second cylinder; and injecting fuel into said second cylinder wherein fuel is provided only to the trailing cylinder when said engine is rotating at between 3500 and 5000 revolutions per minute; and wherein a sparkplug is igniting in both the first and second cylinders despite fuel being provided only into said second cylinder.
The embodiments of the invention and the various features and advantages thereto are more fully explained with references to the non-limiting embodiments and examples that are described and set forth in the following descriptions of those examples. Descriptions of well-known components and techniques may be omitted to avoid obscuring the invention. The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those skilled in the art to practice the invention. Accordingly, the examples and embodiments set forth herein should not be construed as limiting the scope of the invention, which is defined by the claims.
As used herein, terms such as “a,” “an,” and “the” include singular and plural referents unless the context clearly demands otherwise.
As used herein, the term “about” means within 10% of a stated number.
In each figure, the large circles at the bottom represent the crankshaft 10, which is shown oriented to depict the offset nature of the connecting rods. The two circles are a single crankshaft, simply rotated 90 degrees to depict the offset nature. Similarly,
The right piston 21 is offset from the left piston 22 and is trailing. When the left piston 22 is at top dead center, the angle 27 of offset of the right piston 21, as measured from where the right connecting rod 28 meets the crankshaft 10, is between about 8 and 12 degrees trailing of the right connecting rod 26. Timing of an engine is often described in degrees, and the timing of certain components is thus described in degrees corresponding to the timing. Here, the parallel pistons 22 and 21 and in fluid communication with one another because of the open head space 23, and the trailing piston 21 is offset by between 8 to 12 degrees. In other words, the connecting rods to the crank shaft enable the trailing piston 21 to be offset from the leading piston 22 by about 8-12 degrees. Thus, the right connecting rod 28 is not completely vertical and the right piston 21 is before dead center in the right cylinder 25. The trailing piston will always be the second piston, which impacts the fuel added to the relative cylinders and the timing and firing of the sparkplugs 32.
Indeed, as depicted, the left (leading) piston 22 and right (trailing) piston 21 are operated together in a single cavity, such that the space in the head opening 23 connects the two cylinders 24 and 25. This head opening 23 is defined between the top of the cylinder and the bottom of the cylinder head and provides that the intake, compression, power, and exhaust is occurring within the two cylinders, because of their fluid communication in this head opening 23—as compared to a typical engine, where each cylinder operates independent of other cylinders. One advantage of the system is that where a typical engine fires before top dead center, a portion of the force on the cylinder is wasted and results in inefficiencies. By pairing the two pistons/cylinders, a single explosion within the two cylinders will begin to affect at least one of the pistons as it is past top dead center, therefore allowing the full force of the explosion to push that piston, where the trailing piston is then pulled past top dead center, and then continues to push down due to the explosion.
Furthermore, the pushing, and pulling of gas and fuel is greatly improved by the offset nature. For example, as the intake stroke continues, into the compression stroke, as seen in
As further defined in
The cams 30 and 31 are necessary components to allow for the four strokes, the intake, compression, power, and exhaust strokes, by moving the relevant valves 51-54 to allow for air to enter, on the intake, close for compression, close for power, and then exhaust after the power stroke. These valves work with a camshaft 11 that has an appropriate offset in view of the offset of the crankshaft 10. The camshaft 11 rotates at one-half the speed of the crankshaft 10. However, to properly operate, the camshaft 11 must also have an offset for the second cylinder 25 at a rate of one-half the offset of the crankshaft 10. For example, a crankshaft 10 having an offset of 8 degrees would have a camshaft offset of 4 degrees for the second cylinder. This would then retard the opening and closing of valves 53 and 54 by 4 degrees as compared to valves 51 and 52.
Table 1 depicts the range of crankshaft offset suitable for the production engine, and the corresponding camshaft offset.
The angle of offset between the two pistons will depend on the size of the engine, the RPM's obtained and other features known to one of ordinary skill in the art. In the embodiment of
By adjusting the offset angle 27, the compression in the head opening 23 can be modified to maximize performance of the engine. Similarly, the amount of space in the head opening 23 can be modified to enlarge or minimize the opening space to modify the amount of possible compression and to allow for optimal gas exchange between the two cylinders. However, at no time is the head opening 23 closed; therefore, the two cylinders/pistons are always connected via this head opening 23 space. For example, the cylinder head 20 can be machined to have a single tube for gas exchange, or a larger groove. In each case, the space should not restrict flow to allow for the efficient exchange of gasses in each piston, while the smaller size allows for increased head pressure.
Generally, a functioning engine would comprise a single pair of cylinders, or, alternatively, two, three, or four pairs, or more pairs of cylinders to maintain balance. The additional cylinders may be oriented in-line, or offset in any of the orientations known of one of skill in the art. For conventional engines for typical use in recreational vehicles, or for other small scale uses, the typical engine will have one or two pairs of cylinders.
It would be feasible to take a straight 8 cylinder, or an angled 8 cylinder engine and modify various components of the engine, i.e. the cylinder head 20, so as to introduce a head opening 23, as between the previously unconnected cylinders. With additional modifications to the connecting rods 26 and 28 and other features of the engine to form the offset paired cylinders. Indeed, by having an engine with 8 cylinders, each of the four pairs could be starting one of the four cycles of the Otto cycle, as a mechanism to balance the engine and optimize the efficiency.
Similarly, a four cylinder engine could have one pair beginning the firing cycle and the other beginning the intake cycle. Alternatively, it may be advantageous to have each pair offset as to another pair of cylinders.
This design of this embodiment differs significantly from other designs in which two pistons are pushed from a single explosion via the opposing cylinder engine. There, the pistons fire in opposing directions. Here, the cylinders are intended to be substantially parallel to one another, but the pistons within the cylinders are offset. That allows for the modification in the head to allow for the connection of the two cylinders. The design herein provides for a significant advantage in operating efficiency as compared to prior art engines.
The engine cycle is appropriately detailed through
Test 5 repeated Test 2, with modified timing, both advanced and retarded—and resulted in a reduction in the efficiency, from optimal timing. Accordingly, the optimal operating procedure is defined by test 2, which indicates that no fuel is provided to the leading cylinder, i.e. cylinder 24 or the left cylinder in the images. Thus, all fuel is provided to the cylinder 25 having the trailing piston 21. Interestingly, if you swap the fuel, and have only fuel to the leading cylinder 24, the engine stalls and will not run as shown in Test 4 in the above table. Yet, fuel to both chambers has the engine running rich and thus wastes fuel. This surprising effect of fuel injection to only the trailing cylinder leads to some of the increased fuel efficiency we see in this engine.
At the end of the compression stroke and beginning of the power stroke, e.g.
Finally, as in
As defined in more detail in
The push rods, e.g. 62 and 63 would connect to one or more feature of the camshaft and to the valve assemblies, to open and close the valves 51-54. In certain embodiments, it may be advantageous to use a crankshaft or features that are irregular shaped, so that as they turn, a point or a flat section will push onto the cams to open or close valves. Those of skill in the art will recognize the modifications necessary to enable timing for the particular engine.
The below tests utilized an engine having an offset crankshaft of 12 degrees and an offset camshaft of 6 degrees for the trailing cylinder. Based on the earlier test, we recognize that it is advantageous to not include fuel in the first cylinder. However, even fuel in the first cylinder was tested below for relative comparisons. Tests 2 and 3 tested the difference with ignition and no ignition in the first cylinder. Test 4 concluded that the engine would not run with no fuel in the second cylinder. Test 5 tested two further variations of Test 2, advancing timing 7 further degrees of firing of the spark. Test 6 is a standard engine of the same variety, having no parallel cylinders. Each engine orientations were tested at 3500, 4000, 4500, and 5000 RPM as provided in as below in Table 3:
Accordingly, the engines of tests 2 and 3 are the leanest running engines and thus are optimized. This allows greater fuel efficiency over a standard engine of the same build, and would lead to dramatic gains in fuel economy. This is particularly surprising, that small modifications in the orientation as well as in the mixture of fuel into only the trailing cylinder would result in such dramatic improvements in fuel economy over a standard engine. There is a slight exchange in the fuel economy for HP. For example, the engine of Tests 2 and 3 above, ran at about 20% reduction of horsepower as compared to the standard engine. However, most engines do not need the additional power, and most engines typically run nowhere near their maximum RPM.
The efficiency of the engine is compared here and shown to have an increase over standard engines. While fuel to both cylinders increases power, this would not result in a greater efficiency, as shown above in table 3. Accordingly, where power is needed, or for starting, for example, fuel may be injected into both cylinders, thus the first cylinder 24 possesses a fuel injector 40.
Accordingly, a particular feature of the invention is that a replacement head and replacement connecting rod, and camshaft are relatively inexpensive to manufacture and can be modified on an existing engine to create a modified paired cylinder engine as described in the various embodiments herein. Accordingly, a further embodiment of the invention is a kit or a system comprising a modified head having disposed openings that are situated between a pair of cylinders, and further comprising one or more replacement connecting rods to augment the angle of at least one piston in the engine, so as to pair the cylinders and create an offset angle of between 8 and 12 degrees between the paired cylinders, and a camshaft enabling an offset of between 4 and 6 degrees, corresponding to one-half of the offset of the crankshaft. The result of the system is a kit that can be utilized with a standard engine to modify it to having paired cylinders. No other similar system or kit currently exists.
Although the present invention has been described in considerable detail, those skilled in the art will appreciate that numerous changes and modifications may be made to the embodiments and preferred embodiments of the invention and that such changes and modifications may be made without departing from the spirit of the invention. It is therefore intended that the appended claims cover all equivalent variations as fall within the scope of the invention.
This application is a continuation in part of U.S. application Ser. No. 14/282,201 filed May 20, 2014, which claims priority to U.S. Provisional Application Ser. No. 61/831,491, filed Jun. 5, 2013, which are hereby incorporated by reference in their entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61831491 | Jun 2013 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 14282201 | May 2014 | US |
| Child | 15821138 | US |
