This invention relates to a method of deriving mechanical work from combusting gas in an internal combustion engine by means of a new thermodynamic working cycle and to reciprocating internal combustion engines for carrying out the method.
As the expansion ratio of an internal combustion engine is increased, more energy is extracted from the combustion gases and converted to kinetic energy, increasing the thermodynamic efficiency of the engine. Increasing air charge density increases both power and fuel efficiency due to further thermodynamic improvements. Typical objectives for an efficient engine are to provide a high-density charge, begin combustion at maximum density and then expand the gases as far as possible against a piston
Briefly described, the present invention comprises an internal combustion engine system (including methods and apparatuses) for managing combustion charge densities, temperatures, pressures and turbulence in order to produce a true mastery within the power cylinder in order to increase fuel economy, power and torque while minimizing polluting emissions. In its preferred embodiments, the method includes the steps of (i) producing an air charge, (ii) controlling the temperature, density and pressure of the air charge (iii) transferring the air charge to a power cylinder of the engine such that an air charge having a weight and density selected from a range of weight and density levels ranging from atmospheric weight and density to a heavier-than-atmospheric weight and density is introduced into the power cylinder, and (iv) then compressing the air charge at a low “effective” compression ratio, (v) causing a pre-determined quantity of charge-air and fuel to produce a combustible mixture, (vi) causing the mixture to be ignited within the power cylinder, and (vii) allowing the combustion gas to expand against a piston operable in the power cylinder with the expansion ratio of the power cylinder being substantially greater than the effective compression ratio of the power cylinders of the engine. In addition to other advantages, the invented method is capable of producing mean effective [cylinder] pressures (“mep”) which are much higher than produced by traditional Otto, Miller and Diesel cycle engines. In the preferred, but not all, embodiments, the mean effective cylinder pressure is alternatively, selectively variable (and selectively varied) throughout a wide range during the operation of the engine.
Many principles and structures of relevance to the present invention are found in the disclosures of my prior U.S. patent application Ser. Nos. 08/863,103 (now U.S. Pat. No. 6,279,550) and 10/385,588; which disclosures including specification and drawings as well as the disclosure of U.S. provisional application Ser. No. 60/495,997 are all hereby incorporated herein in their entirety by reference.
In its preferred embodiments, the apparatus of the present invention provides a reciprocating internal combustion engine with at least one ancillary compressor for compressing an air charge, an intercooler through which the compressed air can be directed for cooling, power cylinders in which the combustion gas is ignited and expanded, a piston operable in each power cylinder and connected to a crankshaft by a connecting link for rotating the crankshaft in response to reciprocation of each piston, transfer conduit communicating an atmospheric inlet port to the inlet of at least one compressor, a transfer conduit communicating the compressor outlet to a control valve and to the intercooler, a transfer manifold communicating the intercooler with the power cylinders through which manifold the compressed charge is transferred to enter the power cylinders, an intake valve controlling admission of the compressed charge from the transfer manifold to said power cylinders. For the 4-stroke engine of this invention, the intake valves of the power cylinders are timed to operate such that charge air which is (by weight of air per liter) equal to or heavier than charge air utilized in traditional Otto, Miller and Diesel cycle engines can be maintained within the transfer manifold when required and introduced into the power cylinder during the intake stroke, with the intake valve closing at some point during the compression stroke, to provide a low “effective” compression ratio.
According to one embodiment, the intake valve is held closed during the initial portion of the piston intake stroke and then opened and closed in a manner to create and maintain a compression ratio less than the expansion ratio so that ignition can commence at substantially maximum charge density. Means are provided for causing fuel to be mixed with the air charge to produce a combustible gas. In another embodiment, the intake valve can open twice, once opening and closing during the intake stroke and again opening during the later part of the intake stroke, or later, and closing during the compression stroke at a point which captures a charge weight needed to power the engine and at such a time that the effective compression ratio of the engine will be less than the expansion ratio so that ignition can commence at substantially maximum charge density. Means are provided for causing fuel to be mixed with the air charge to produce a combustible gas.
In both systems compression continues and the charge is ignited near TDC for the power stroke, followed by scavenging stroke.
The combustion chambers of the power cylinders are sized with respect to the displaced volume of the power cylinders such that the exploded combustion gas can be expanded to a volume substantially greater than the effective compression ratio of the power cylinders of the engine. The combustion chambers are of a size to establish compression ratios similar to those of a typical Otto or Diesel cycle engines or alternatively are enlarged for more power. In some embodiments where combustion chambers are enlarged, engine stroke and/or cylinder bore are increased to match, concurrently, the increase in charge-air expansion.
In alternate versions of both of the mentioned embodiments, one or more expansion valves are provided in the path of air introduction to the intake valve to effect a chilling of entry air; and the expansion valve can be provided with one or more controllable, variable orifices.
The chief advantages of the present invention over, for example, existing Otto and Miller cycle internal combustion engines are that it provides a cooler working cycle with an effective compression ratio lower than the expansion ratio of the engine and significantly lower than effective compression ratios of Miller cycle engines; and the present invention, provides, selectively, a mean effective cylinder pressure higher than the conventional Otto, Miller and Diesel cycle engine arrangements. These allow greater fuel economy and production of significantly greater power and torque at all RPM, with low polluting emissions.
Various other objects, features, and advantages of the present invention will become more apparent upon review of the detailed description set forth below when taken in conjunction with the accompanying drawing figures.
Referring to
One suggested preferred method of operation of the new cycle engine is thus: this first embodiment comprises a supercharged internal combustion engine in which, selectively, atmospheric air or air-fuel mix is compressed and cooled externally to the engine and introduced during the intake stroke or shortly thereafter, and the intake valve is then closed during the compression stroke at a point that the retained charge weight within cylinder/combustion chamber is sufficient, when mixed with fuel and ignited at piston top-dead-center (TDC), to produce the power and torque desired of the engine. During the first stroke, normally an intake stroke, the intake valve is held closed during the initial part of the stroke. In this system, this first stroke expands any residual gases in the combustion chambers. These expanding gases cool piston and cylinder and enhance the entrance of the air charge which is inducted at some point before or after piston bottom-dead-center (BDC) of the first stroke.
(1) Atmospheric air is received by port 8, filtered, compressed by compressor of turbo charger 1, is passed through after cooler 10, then alternatively, further compressed and temperature adjusted by wholly or partially passing through compressor 2, wholly or partially through intercooler 11 (which is alternatively water cooled), then passed wholly or partially through after-cooler 12 and through conduit B, through intake valve 16 and intake port 416 into chamber 407. The chamber 407 is that chamber formed, in this embodiment by the piston 7 top, cylinder 7 walls, and engine head 404. Alternatively, conduit B contains an expansion valve 410 (or, again optionally, intake port 416 is fitted with an expansion valve) as shown and illustrated in conduit B. Alternatively, conduit to compressor 2 is fitted with an air bypass system consisting of bypass valve R1 and conduit X1; conduit to intercooler 11 is fitted with bypass valve R2 and bypass conduit X2, conduit from intercooler 11 to intercooler 12 is fitted with a bypass valve R3 and bypass conduit X3, whereby the valving and bypass system so constructed that said R control valves, activated by sensors within the system, send messages concerning temperatures of the passing fluid to alternate engine control module, ECM-27 to alternatively cause R valves to individually pass the transmitted fluids wholly or partially through intercoolers or cause wholly or partially to bypass the compressor 2 or cooler 12, 13, in order to adjust pressure and temperature to that desired for best engine performance. Expansion valve 410, regardless of position in the inlet conduit, has, alternatively, a variable orifice (opening) controlled alternatively by ECM-27 which adjusts the size of the orifice, if present, to that producing a desired temperature of the charge air. The very high pressure air or air-fuel charge is delivered to intake valve 16 and inlet port 416 and is utilized in this fashion:
(2) Valve 16 and inlet port 416 are kept closed through the first part of the first (normally intake) stroke.
(3) At a time deemed optimal, before piston 22 bottom-dead-center or after, intake valve 16 and inlet port 416 open to induct the cool, dense air or air-fuel charge into the chamber 407. The valve 16 is held open long enough that the charge inducted has time to fill chamber 407 and, possibly for piston 22, during compression (2nd) stroke, (alternatively) to expel a portion of charge back through intake port 416 and valve 16 and into manifold 14. Alternatively any excess charge is expelled through an ancillary valve (not shown) with proper back pressure to prevent pressure drop. Port 416 and valve 16 are then closed at a predetermined point of piston 22 travel in the compression stroke. In alternate embodiments, the point of closure of intake valve 16 and inlet port 416 is variable and varied using, for example, valve controlling devices known in the industry. When the port and valve are closed, a charge is trapped and retained which when mixed with fuel, if not already present, and ignited will cause the engine to produce the power and torque required of the engine at that moment. According to preferred, but not all, embodiments, the point of closure of the intake valve 16 and inlet port 416 occurs after the piston has traveled through a meaningful portion of the compression stroke, for example, at or after 25% and, preferably, after 50% of the compression stroke has been traveled. More preferably, in alternate embodiments, the closure takes place as late as possible in the compression stroke while still providing enough time after the closure for the trapping of air to be complete and ignition of the fuel/air combination to take place no later than at the point of piston top dead center at the end of the compression stroke. According to one example, the closure of intake valve 16 and inlet port 416 occurs at a point in piston travel of approximately 15°-20° before top dead center.
(4) Compression continues on the trapped portion of charge and near piston 22 top-dead-center, the charge is fueled, if fuel is not present, and ignited, producing great power, for the power/expansion (3rd) stroke, followed by the scavenging (4th) stroke to complete one power cycle.
Referring to
(1) Atmospheric air or air-fuel is inducted by inlet duct 8, filtered into and compressed by turbo charger 1, further compressed by compressor 2, cooled by at least one of intercoolers 10, 11 and 12. The charge has its temperature and pressure adjusted by compressor and cooler system the same as for the engine of Model I. The optimal charge is inducted, cool or “chilled”, by intake conduit B, intake valve 16B and inlet port 416B (shown in
As in Model I, the air or air-fuel charge alternatively, has its pressure and temperature adjusted by the compression-cooling-bypass system, alternatively controlled by engine control module (ECM-27),
(2) Atmospheric air inducted by port 8 of
Referring again to
In Mode Two, valve 16A, has a cam 21B on which a single lobe 21E has a profile matching lobe 21C on cam 21, which cam 21 opens and closes valve 16B and inlet port 416B. Lobe 21D of cam 21 is missing on cam 21B. Therefore, alternatively, this arrangement is constructed such that during each firing cycle: (a) lobe 21D first opens and closes valve 16B during an intake stroke of piston 22; and (b) subsequently, and in unison or approximately in unison, lobe 21C and lobe 21E open and close their respective valves 16B, 16A and ports 416B, 416A. This permits much faster charging of the chamber 407.
The engine can operate in this mode continuously as “steady-state” power for heavy duty operation.
The engine of Model II of
In this “intermittent” mode, (Mode Three), the engine can operate in Mode One for cruising or at any time less power is required, and can then be switched to Mode Two at anytime great power is needed. Engaging and disengaging the cam 21B can be accomplished in any of numerous ways known in the art of valve and cam control.
It will be seen by the foregoing description of a plurality of embodiments of the present invention, that the advantages sought from the present invention are common to all embodiments.
While there have been herein described approved embodiments of this invention, it will be understood that many and various changes and modifications in form, arrangement of parts and details of construction thereof may be made without departing from the spirit of the invention and that all such changes and modifications as fall within the scope of the appended claims are contemplated as a part of this invention.
While the embodiments of the present invention which have been disclosed herein are the preferred forms, other embodiments of the present invention will suggest themselves to persons skilled in the art in view of this disclosure. Therefore, it will be understood that variations and modifications can be affected within the spirit and scope of the invention and that the scope of the present invention should only be limited by the claims below. Furthermore, the equivalents of all means-or-step-plus-function elements in the claims below are intended to include any structure, material, or acts for performing the function as specifically claimed and as would be understood by persons skilled in the art of this disclosure, without suggesting that any of the structure, material, or acts are more obvious by virtue of their association with other elements.
This application claims the benefit of provisional patent application No. 60/495,997, filed Aug. 18, 2003.
Number | Date | Country | |
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60495997 | Aug 2003 | US |