Patent Grant
8365699
The present invention relates to engines, and specifically, to hybrid cycle rotary engines.
Excluding very large ship diesels, the typical maximum efficiency of modern internal combustion engines (ICE) is only about 30-35%. Because this efficiency is only attainable in a narrow band of loads (normally close to full load) and because most vehicles typically operate at partial load around 70% to 90% of the times, it should not be surprising that overall, or “well to wheel,” efficiency is only 12.6% for city driving and 20.2% for highway driving for typical mid-size vehicle.
There is prior art in which a Homogeneous Charge Compression Ignition (HCCI) cycle offers to improve the efficiency of internal combustion engines. While offering some advantages over existing engines, they too, however, fall short in providing high maximal efficiency. In addition, HCCI cycle engines also are polluting (particulate matter) and are difficult and costly to control because the ignition event is spontaneous and function of great many variables such as pressure, temperature, exhaust gas concentration, water vapor content, etc.
In one embodiment, the invention provides an engine. The engine of this embodiment includes a source of a pressurized working medium and an expander. The expander includes a housing, a piston, an intake port, an exhaust port, a septum, and a heat input. The piston is movably mounted within and with respect to the housing, to perform one of rotation and reciprocation. Each complete rotation or reciprocation defines at least a part of a cycle of the engine. The intake port is coupled between the source and the housing, to permit entry of the working medium into the housing. The exhaust port is coupled to the housing, to permit exit of expended working medium from within the housing. The septum is mounted within the housing and movable with respect to the housing and the piston so as to define in conjunction therewith, over first and second angular ranges of the cycle, a working chamber that is isolated from the intake port and the exhaust port. The heat input is coupled to the working medium at least over the first angular range of the cycle to provide heat to the working medium and so as to increase its pressure. In this embodiment the working chamber over a second angular range of the cycle expands in volume while the piston receives, from the working medium as a result of its increased pressure, a force relative to the housing that causes motion of the piston relative to the housing.
In a further related embodiment, the piston and the septum simultaneously define, at least over the first and second angular ranges of the cycle, an exhaust chamber that is isolated from the intake port but coupled to the exhaust port. Alternatively or in addition, the source includes a pump. Alternatively or in addition, the engine also includes a fuel source coupled to the expander; in this embodiment, the working medium includes one of (i) an oxygen-containing gas to which fuel from the fuel source is added separately in the course of the cycle and (ii) an oxygen-containing-gas with which fuel from the fuel source is mixed outside the course of a cycle, and the heat input is energy release from oxidation of the fuel at least over the first angular range, so that the engine is an internal combustion engine. As a further related embodiment, the working chamber has a volume, over the first angular range, that is substantially constant. Optionally the engine also includes a turbulence-inducing geometry disposed in a fluid path between the source of pressurized working medium and the working chamber to enhance turbulence formation in the working medium. Optionally, the engine also includes a fuel valve assembly coupled between the fuel source and the expander, and a controller, coupled to the fuel valve assembly. The controller is also coupled to obtain engine cycle position information, and controller operates the fuel valve assembly to cut off flow of fuel to the expander during a portion of the cycle when fuel addition is not needed. Also optionally, the engine also includes an air valve assembly coupled between the pressurized working medium source and the expander, and a controller, coupled to the air valve assembly. The controller is also coupled to obtain engine cycle position information, and the controller operates the valve assembly to cut off flow of the working medium to the expander during a portion of the cycle when addition of working medium is not needed. In a further related embodiment, the air valve assembly includes a check valve.
In a further related embodiment, introduction of the pressurized working medium through the intake port into the working chamber causes a temporary drop in the working medium pressure and efficient mixing of the working medium with fuel introduced into the working chamber, under conditions of continually increasing pressure of working medium in the working chamber, until temperature of the fuel-working-medium mixture reaches an ignition temperature resulting in combustion of the mixture. Optionally, such combustion causes an increase of pressure in the working medium that, in turn, causes the check valve to close automatically.
In a further related embodiment, the air valve assembly also includes a second valve coupled to the controller. Optionally, the air valve assembly also includes a latch on the check valve coupled to the controller to maintain the check valve in a closed position when directed by the controller. Optionally, the controller is configured to cause cut off of flow of fuel to the expander during some cycles of the engine so that the engine runs at less than a hundred percent duty cycle. Optionally, operation of the controller to cause cut off of fuel flow to the expander during some cycles of the engine effectuates no substantial reduction of supply of working medium to the expander, so that working medium supplied to the expander when fuel flow to the expander is cut off serves to cool the engine, and the controller is configured to operate the engine under normal conditions at less than one hundred percent duty cycle so as to provide cooling to the engine.
Also in a further related embodiment, the piston is a cam, and the septum is a cam-following rocker, engagable against the cam. Optionally, the engine includes a vessel for coupling the source to the intake port; the vessel includes a volume for storing pressurized working medium. Optionally, the vessel includes an air tank disposed in a location external to the housing. Also optionally, the first and second angular ranges are at least partially overlapping. Alternatively, the first and second angular ranges are non-overlapping. Optionally, the working medium is an oxygen-containing gas, and the engine further includes a fuel injector disposed in a fluid path from the source to a region within the housing. Optionally, the fuel injector is disposed in the intake port.
Also in a further related embodiment, the engine is a modified axial vane rotary engine, wherein the septum is a stator ring, the piston is a vane mounted for axial reciprocation in the stator ring, and the housing is a rotary cam ring that rotates with respect to the stator ring and includes a flattened region defining a dwell period over the first angular range during which the vane is stationary with respect to stator ring.
In yet another related embodiment of an engine in accordance with the present invention, the piston is a reciprocating blade, the septum is a hub having a circular cross section in which the piston is slidably mounted. The housing is concentrically disposed around the hub and rotates with respect to the hub and includes a first interior circular wall portion that maintains sealing contact with the hub in the course of the housing's rotation around the hub and a second wall portion contiguous with the first interior wall portion. The wall portions define, with the blade and the hub, a working chamber over the first and second angular ranges.
Another embodiment of the present invention provides a method of operating an internal combustion engine. The method of this embodiment includes using a cam, rotatably mounted in a housing, and a cam follower, mounted within the housing and movable with respect to the housing, to define, over first and second angular ranges of an engine cycle, a working chamber that is isolated from an intake port and an exhaust port. In this embodiment, the working chamber has substantially constant volume over the first angular range. The method additionally includes introducing fuel into the working chamber; introducing pressurized working medium into the working chamber over a fluid path through the intake port from a source of pressurized working medium, so as to cause a temporary drop in the working medium pressure and efficient mixing of the working medium with fuel introduced into the working chamber, under conditions of continually increasing pressure of working medium in the working chamber. The introduction of pressurized working medium continues until temperature of the fuel-working-medium mixture reaches an ignition temperature resulting in combustion of the mixture. The combustion causes an increase in pressure in the working medium wherein the increase in pressure causes rotation of the cam. The combustion commences within the first angular range.
In a further related embodiment, the method also includes closing a valve in the fluid path between the source of pressurized working medium and the working chamber when pressure in the working chamber exceeds pressure of the source of pressurized working medium. Optionally, the method further includes operating the cam and the cam follower simultaneously at least over the first and second angular ranges of the cycle to define an exhaust chamber that is isolated from the intake port but coupled to the exhaust port.
In another embodiment, the invention provides an internal combustion engine that includes a source of a pressurized working medium and an expander. The expander includes a housing, a cam, an intake port, an exhaust port, and a cam-following rocker. The cam is rotatably mounted within and with respect to the housing. Each complete rotation of the cam defines at least a part of a cycle of the engine. The intake port is coupled between the source and the housing, to permit entry of a working medium into the housing. The exhaust port is coupled to the housing, to permit exit of expended working medium from within the housing. The cam-following rocker is mounted within the housing and movable with respect to the housing and the cam so as to define in conjunction therewith, over first and second angular ranges of the cycle, a working chamber that is isolated from the intake port and the exhaust port. The working medium includes one of (i) an oxygen-containing gas to which fuel is added in the course of the cycle and (ii) an oxygen-containing-gas-fuel mixture. At least over the first angular range, oxidation of the fuel occurs and the working chamber has a volume that is substantially constant. Such oxidation provides heat to the working medium so as to increase its pressure. The working chamber, over a second angular range of the cycle, expands in volume while the cam receives, from the working medium as a result of its increased pressure, a force relative to the housing that causes rotation of the cam.
In a further related embodiment, the cam and the rocker simultaneously define at least over the first and second angular ranges of the cycle an exhaust chamber that is isolated from the intake port but coupled to the exhaust port.
In another embodiment, the invention provides an internal combustion engine that includes a housing, a cam, a cam-following rocker, a combustion chamber formed in the house, an intake port, and an exhaust port. The housing has an interior region with a generally circular cross section defined by an inner surface of the housing, wherein the generally circular cross section is interrupted by a rocker mounting region. The housing also has a pair of sides. The cam is rotatably mounted in the housing, and sweeps a circular path in the interior region. The cam is in sealing contact with the sides of the housing and also, when a leading edge of the cam is not adjacent to the rocker mounting region, is in sealing contact with the inner surface of the housing. The cam-following rocker is mounted in the rocker mounting region, in sealing contact with the sides of the housing, and, at least when the leading edge of the cam is not adjacent to the rocker mounting region, is in sealing contact with the cam. The rocker has a seated position defining generally, when a leading edge of the cam is adjacent to the rocker mounting region, a continuation of the circular cross section of the housing. The rocker is pivoted at a pivot end to move at a free end generally radially with respect to the circular path of the cam, so that the free end of the pivot reciprocates between the seated position and a maximum unseated position. The rocker completes a full reciprocation cycle when the cam completes a revolution around the working region. The combustion chamber is formed in the housing proximate to the rocker mounting region adjacent to the free end of the rocker, and has an opening. The opening is occluded over a first angular range of rotation of the cam. The inlet port is coupled to the combustion chamber for providing pressurized working medium. The working medium includes one of (i) an oxygen-containing gas to which fuel is added within or before the first angular range and (ii) an oxygen-containing-gas-fuel mixture. Combustion occurs within the first angular range so as to provide substantially constant volume combustion in the combustion chamber. The cam and the rocker are configured to provide an expansion region over a second angular range when the arcuate opening is not occluded. The exhaust port is formed in the housing proximate to the rocker mounting region adjacent to the free end of the rocker, for removing expended working medium.
In yet another embodiment, the invention provides an internal combustion engine that includes a housing, a piston, an intake port, an exhaust port, and a cam. The piston is reciprocally mounted within and with respect to the housing. Each complete reciprocation of the piston defines at least a part of a cycle of the engine, and each stroke of the piston defines its displacement in a working chamber of the housing. The intake port is coupled between the pump and the working chamber, to permit entry of the working medium into the working chamber. The working medium includes one of (i) an oxygen-containing gas to which fuel is added in the course of the cycle and (ii) an oxygen-containing-gas-fuel mixture. The exhaust port is coupled to the working chamber, to permit exit of expended working medium from within the working chamber. The cam is coupled to the piston, and defines displacement of the piston as a function of angular extent of the cycle. In this embodiment, at least over a first angular range of the cycle, oxidation of the fuel occurs and the cam has a shape that causes substantially no displacement of the piston, so that the working chamber has a volume that is substantially constant. Such oxidation provides heat to the working medium so as to increase its pressure. The working chamber, over a second angular range of the cycle, expands in volume while the piston receives, from the working medium as a result of its increased pressure, a force relative to the housing that causes displacement of the piston.
In another embodiment, the invention provides a virtual piston assembly that includes a body including at least one fluidic diode and a member rotatably mounted within the body. The member includes at least one fluidic diode. The member is disposed in relation to the body, and the body has a correspondingly shaped interior, so as to form a virtual chamber having a volume that varies with rotation of the member.
In a further related embodiment, the member is a disk. In another related embodiment, the member is cylindrical. In yet another related embodiment, the member is conical.
In another embodiment, the invention provides a pump that includes a housing, a cam, an intake port, an exhaust port, and a cam following rocker. The cam is rotatably mounted within and with respect to the housing. Each complete rotation of the cam defines at least a part of a pumping cycle. The intake port is coupled between the pump and the housing, to permit entry of a fluid. The exhaust port is coupled to the housing, to permit exit of pumped fluid from within the housing. The cam-following rocker is mounted within the housing and movable with respect to the housing and the cam so as to define in conjunction therewith, a working chamber that over a first angular range of the cycle is isolated from the from the intake port and from the exhaust port.
In a further related embodiment, the pump is a compressor, and the working chamber is a compression chamber. Optionally, the compression chamber over a second angular range remains isolated from the intake port but coupled to the exhaust port. Optionally, the rocker and the cam simultaneously define at least over the first angular range an intake chamber that is isolated from the exhaust port and coupled to the intake port.
In yet another embodiment, the invention provides an internal combustion engine that includes a source of a pressurized working medium, a fuel source, and an expander. The fuel source is optionally a pump. The expander includes a housing, a piston an intake port, an exhaust port, and a septum. The piston is movably mounted within and with respect to the housing, and performs one of rotation and reciprocation. Each complete rotation or reciprocation defines at least a part of a cycle of the engine. The intake port is coupled between the source and the housing, to permit entry of the working medium into the housing. Optionally, a turbulence-inducing geometry is disposed in a fluid path between the source of pressurized working medium and the working chamber to enhance turbulence formation in the working medium. The exhaust port is coupled to the housing, to permit exit of expended working medium from within the housing. The septum is mounted within the housing and movable with respect to the housing and the piston so as to define in conjunction therewith, over first and second angular ranges of the cycle, a working chamber that is isolated from the intake port and the exhaust port. Also the working chamber has a volume, over the first angular range, that is substantially constant, and the piston and the septum simultaneously define at least over the first and second angular ranges of the cycle, an exhaust chamber that is isolated from the intake port but coupled to the exhaust port. The working medium includes one of (i) an oxygen-containing gas to which fuel from the fuel source is added separately in the course of the cycle and (ii) an oxygen-containing-gas with which fuel from the fuel source is mixed outside the course of a cycle. The fuel undergoes combustion in the working chamber at least over the first angular range. The combustion provides heat to the working medium so as to increase its pressure. The working chamber over a second angular range of the cycle expands in volume while the piston receives, from the working medium as a result of its increased pressure, a force relative to the housing that causes motion of the piston relative to the housing. Optionally the embodiment includes a fuel valve assembly coupled between the fuel source and the expander. Also optionally, the embodiment includes an air valve assembly coupled between the pressurized working medium source and the expander. The air valve assembly optionally includes a check valve. Optionally, the embodiment includes a controller, coupled to the optional fuel valve assembly and to the optional air valve assembly. The controller is also coupled to obtain engine cycle position information, and operates the optional air valve assembly to cut off flow of the working medium to the expander during a portion of the cycle when addition of working medium is not needed and operates the optional fuel valve assembly to cut off flow of fuel to the expander during a portion of the cycle when fuel addition is not needed. Also optionally, the controller is configured to cause cut off of flow of fuel to the expander during some cycles of the engine so that the engine runs at less than a hundred percent duty cycle. Also optionally, operation of the controller to cause cut off of fuel flow to the expander during some cycles of the engine effectuates no substantial reduction of supply of working medium to the expander, so that working medium supplied to the expander when fuel flow to the expander is cut off serves to cool the engine; in such a case the controller is configured to operate the engine under normal conditions at less than one hundred percent duty cycle so as to provide cooling to the engine. Optionally the piston is a cam, and the septum is a cam-following rocker, engagable against the cam. Optionally introduction of the pressurized working medium through the intake port into the working chamber causes a temporary drop in the working medium pressure and efficient mixing of the working medium with fuel introduced into the working chamber, under conditions of continually increasing pressure of working medium in the working chamber, until temperature of the fuel-working-medium mixture reaches an ignition temperature resulting in combustion of the mixture; such combustion causes an increase of pressure in the working medium that, in turn, causes the check valve to close automatically.
Definitions. As used in this description and the accompanying claims, the following terms shall have the meanings indicated, unless the context otherwise requires:
“Sealing contact” of two members shall mean that the members have sufficient proximity directly, or via one or more sealing components, so as to have acceptably small leakage between the two members. A sealing contact can be intermittent when the members are not always proximate to one another.
A port is “coupled” to a chamber when at least some of the time during a cycle it is in communication with the chamber.
A full “reciprocation cycle” of a rocker that reciprocates between seated position and a maximum unseated position includes 360 degrees of travel of the main shaft, wherein travel from one of such positions to the other of such positions amounts to 180 degrees of travel of the main shaft.
The “working medium” describes the various substances which may usefully injected into the working chamber, In the case of an internal combustion engine, “working medium” includes an oxygen-containing gas either by itself (in which case fuel is added in the course of a cycle) or mixed with fuel outside the course of a cycle. The oxygen-containing gas may include air or oxygen, alone or mixed, for example, with one or more of water, superheated water, and nitrogen.
The “working chamber” of an engine relates collectively to the portions thereof (i) wherein a heat input is received (being a combustion chamber in the case of an internal combustion engine) and (ii) wherein expansion caused by increased pressure on account of delivery of heat is used to drive a piston that reciprocates or rotates in the engine.
PGM 200 receives compressed air 305 from CAM 100 and fuel from fuel supply 304. PGM 200 combusts fuel under essentially constant volume conditions and expands the combustion products in an expander 201 (shown in
Entry of fuel from fuel supply 304 is gated by fuel valve assembly 318. If fuel takes the left-hand dotted path just described, then the fuel valve assembly 318 may be implemented as an injector valve. In addition, the controller 319 causes operation of the fuel valve assembly 318 to maintain the fuel supply in an off position during the portion of the cycle when fuel addition is not needed. Additionally, the controller 319 is used to keep fuel cut off during “off-cycles” described below in connection with the “digital mode of operation”. The controller 319 has a variety of engine parameter and user inputs. It obtains cycle position information from a location such as the output shaft of the engine and uses this position information to control the fuel valve assembly 318. Furthermore, the controller obtains user input as to desired power (which in the case of the engine's being used in an automobile corresponds to accelerator pedal position), the engine speed, the engine wall temperature, as well as other optional parameters, to decide whether or not the cycle should fire (on) or be skipped (off) and whether the fuel only should be cut off, or both fuel and air cut off. Alternatively or in addition, the controller is configured to determine the amount of fuel to be supplied in each cycle.
The controller may operate totally mechanically—control of fuel injection in early diesel engines was achieved with total mechanical control, for example—and analogous techniques may be employed in this different context in order to achieve the necessary control. Alternatively, the controller may use a microprocessor operating with a suitable program, in a manner known in the art, to provide electronic control of the valve assembly, and the valve-assembly under such circumstances may include, for example, a solenoid-operated valve that is responsive to the controller.
The structure of engine 1000 is now described with reference to
Compressor 101, which is the main element of CAM 100, consists of the following components, shown in
There are two types of chambers in compressor 101, which are now described with reference to
The spaces between housing 202, separating plate 301 (
The operation of compressor 101 is now described with reference to
The operation of expander 201 is now described with reference to
When air 305 is injected into combustion chamber 212 from air buffer 105, it is initially decompressed (and cooled) and then recompressed (and re-heated) when pressure in the combustion chamber 212 reaches the pressure in air buffer 105. Due to the large pressure difference between the air buffer 005 and compression chamber 212 (which is initially at ambient pressure), the air 305 entering the combustion chamber 212 forms a supersonic swirl which rotates at high rpm. Turbulence formation may be enhanced by use of suitable structures built into the combustion chamber. Description of a Hilsch vortex tube used in carburetor design appears in U.S. Pat. No. 2,650,582, which is hereby incorporated herein by reference. For example, vortex tubes having approximately the same geometry as the combustion chamber 212 have been known to support vortices as high as 1,000,000 rpm, and the input pressure into a vortex tube is only 100 psi as compared to 800-900 psi for an HCRE. Vortex formulation increases turbulence and enhances mixing. The fuel from fuel supply 304 injected simultaneously with the compressed air 305 into a low pressure environment will be dragged into compression chamber 212 by the air swirl, mix very well with the air and evaporate very quickly. When temperature and pressure reaches the auto-ignition point, fuel 304 will ignite within the whole volume (similar to an HCCI engine). At this point, intake of the working medium of compressed air 305 and fuel from fuel supply 304 stops.
As explained above, various chambers are formed between the housings 102, 202, separating plate 301, cams, 103, 203 and rockers 104, 204. It is advantageous for efficient operation of engine 1000 to have tight seals between all these components. Wankel-type face and apex seals 310, as shown in operation in
Engine 1000 may be cooled by conventional means, i.e., passing water 306 through stationary components in a water jacket and air cooling housing walls 102, 202. Alternatively, engine 1000 can be cooled by passing water 306 through the channels formed between various components of engine 1000, which see lots of heat. Finally cooling may be achieved in whole or in part by running at less than 100 percent duty cycle, as explained below in connection with the “digital mode of operation”.
An HCRE engine as in embodiments of the present invention differs in significant ways from a conventional HCCI cycle engine. For example, modern HCCI engines experience problems achieving dynamic operation of the engine. The control system must change the conditions that induce combustion. At present, very complicated, expensive and not always reliable controls are used to effect marginal variation of engine performance in response to varying load conditions. The variables under control to induce combustion include the compression ratio, the inducted gas temperature, the inducted gas pressure, and the quantity of retained or re-inducted exhaust.
In HCRE, additional control means exist that do not require complicated control mechanisms, referred to as combustion stimulation means (CSM). CSM are the measures taken to stimulate or induce the combustion of a conditioned working medium of air and fuel within combustion chamber 212, including, but not limited to, one or more of the following: the pressure of the conditioned working medium, the temperature of the conditioned working medium, the concentration of exhaust gas recirculation (EGR) within the conditioned working medium, the concentration of water vapors within the conditioned working medium, catalytic surfaces within combustion chamber 212 (i.e. walls covered with a catalyst or a catalyst placed within combustion chamber 212), a catalytic burner placed within combustion chamber 212 (such as nickel mesh, or ceramic foam), high combustion chamber wall temperature, a tungsten wire heater inside combustion chamber 212, re-inducted exhaust 307 (which alone or in mixture with water vapor might induce a water shift reaction within fuel from fuel supply 304 as a thermo-chemical recuperator), and additional fuel injected or introduced into combustion chamber 212. This additional fuel may be, but does not have to be, the same as fuel from fuel supply 304, i.e. fuel produced by dissociation of water (steam) molecules in the presence of a catalyst and possibly assisted by an electric spark discharge into hydrogen and oxygen. This can be produced by electrolysis of water (or steam) within the confines of combustion chamber 212 itself utilizing the heat of engine 1000. The heat generated during the air/fuel mixture compression may supply a significant part of the energy needed for such dissociation. Hydrogen generated in the process of dissociation is used during combustion. Thus, the net effect of this process is partial recovery of the heat of compression.
As mentioned above, engines running under HCCI cycles are notoriously difficult to control, especially under part-load. While standard means of control, such as regulating fuel amount, pressure, temperature, amount of EGR, etc. are still available, a more elegant way to control HCRE (which will be referred to as “digital mode of operation”) is available: to run every cycle at full load, but sometimes skip cycles. For example, skipping three out of each eight cycles will enable running under ⅝th of full power, skipping six out of each eight cycles will enable running under ¼ of full power, and so on.
To operate in the digital mode, and in particular to skip one or more cycles, it is possible to cut off both the compressed air 305 and the fuel supply 304 or to cut off only the fuel supply 304. As described previously in connection with
In a related embodiment, a plurality of expanders may be employed. In such a case, a separate valve assembly for each expander may be employed, although the valve assemblies may be controlled by a common controller 319. The expanders may be mounted on a common shaft at differing angular orientations, so that they operate out of phase with one another in order to smooth out power generation over the course of a shaft rotation. Alternatively, for example, a pair of expanders may be mounted at a common angular orientation but operated with alternate off cycles, any given time one expander is generating power while the other expander has an off cycle, and in this way, the overall engine will exhibit a generally balanced mode of operation. A flywheel may also be used to smooth out engine operation.
If engine 1000 is equipped with external tank 107 and clutches 261 (see
External tank 107 can also start engine 1000 instead of or in addition to an electrical starter, or expander 201 can serve as an air motor running on compressed air 305 or liquid nitrogen.
From the first law of thermodynamics it follows that the less heat is rejected to the environment, the more heat can be converted into useful work. Heat is rejected from an internal combustion engine into the environment via two mechanisms. One is thermodynamic losses due to hot exhaust gases, and the other is engineering losses, due to the need to cool engine components. Low heat rejection (LHR) engines use high temperature components to address the second of these.
Theoretically, LHR engines should exhibit higher thermodynamic efficiencies. In practice, however, the results are inconclusive at best and opposite to what is expected at worst. This in because incomplete combustion due to higher engine temperature forces premature ignition before the fuel has time to mix with the air. Also, higher combustion temperatures result in higher exhaust temperatures. Thus, decreased engineering loss is accomplished at the cost of increased thermodynamic loss.
The design of engine 1000 may present us with an opportunity to address both components of loss at once. The approach includes but is not limited to some or all of the following measures.
One option is thermally insulating the engine from the environment by using ceramic components, various coatings, or other insulation materials. Another option is suppressing the temperature increase of components (housing 102, 202, bearings 207, cover 216 and blade 214) by removing extra heat from these components. Unlike conventional engines which remove heat from the walls and transfer it to the environment through coolant and a heat exchanger (radiator), engine 1000 could be cooled by injecting water 306 between the components. For an example of how water 306, shown in
Many variations on the design of the exemplary embodiment are possible and apparent to those skilled in the art. Examples of various embodiments of the present invention are described below.
Cams 103, 203 may be implemented according to several alternatives. Cams 103, 203 may be implemented in various shapes, the cylindrical surface could be replaced with conical, semi-spherical, or curved surfaces. The functions of cams 103, 203 can be fulfilled by using variations such as groove-cams 114, shown in
It is possible to build a combination compressor/expander 302 (see
It can be shown that, unlike compressor 101, the efficiency of engine 1000 is increased if air 303 is heated during the compression process, rather than cooled. So to increase the efficiency, some of the heat from the exhaust gases 307 could be transferred to air 303 being compressed. It has to be done intermittently from the point in time when cam 103 closes intake port 111 to the point in space when temperature due to compression reaches the maximum temperature of exhaust gases 307 (minus ˜20° C.) (see
Given the extreme heat felt by combustion chamber 212, greater cooling efforts could be undertaken near combustion chamber 212 and lesser cooling at the end of expansion. Similarly, as much higher pressures exist in the vicinity of combustion chamber 212, that is the place where the walls should be the thickest. Other possible variations also include a sliding rocker with an eccentric disk cam, and a fixed and stationary combustion chamber. Still another variation is to locate the combustion chambers within the separating plate or the rocker, or some combination of thereof.
One variation of the basic engine design showing the variety of ways the design ideas can be implemented is a design using a sliding blade 214 (see
The implementation of a PGM 200 according to a sliding blade embodiment is now described with reference to
The spaces between hub 220, housing walls 221, sliding blade assembly 214, bearings 207, and cover 216 define engine chambers. There are three types of chambers, as shown in
The operation of expander 222 in this embodiment is now described with reference to
A working medium (WM), such as air 305, is admitted to combustion chamber 206 through an electronically controlled valve (not shown but corresponding to a portion of air valve assembly 118), located within bearing 207. Alternatively, or in addition to electronically controlled valve, WM gets to combustion chamber 206 through a one way valve (not shown but corresponding to a portion of air valve assembly 118) located within bearing 207. When combustion starts and pressure increases rapidly, the one way valve closes, trapping air 305 inside combustion chamber 206.
If conditioned air is used, fuel from fuel supply 304 is injected by fuel injectors located within bearing 207. If conditioned air or air/fuel mixture is used, the combustion occurs spontaneously within combustion chamber 206 triggered by a combustion stimulation means. If a conditioned air/fuel mixture is used, since the air/fuel mixture is lean as with any homogenous charge compression ignition (HCCI) cycle, the amount of fuel from fuel supply 304 can, to a certain degree, control the power level of engine 1000. However, such a control is unreliable and very complex. All modern engines running the HCCI cycle suffer from this problem. In a further embodiment, in addition or instead of the above control scheme, to run engine 1000 at full power during each cycle, i.e. run under a constant air/fuel mix. The power level of engine 1000 will be controlled, however, by skipping some of the cycles, e.g., executing the digital mode of operation.
Depending on the temperature of housing walls 221, water vapor content and the amount of exhaust gases 207 remaining within combustion chamber 206 from the previous cycle, etc., the combustion event may occur at different positions of sliding blade assembly 214 with respect to housing walls 221, but always will start within combustion chamber 206. Due to the fact that combustion event is very rapid, because fuel from fuel supply 304 is well premixed within combustion chamber 206 and combustion starts simultaneously at all points of combustion chamber 206, the event is very rapid and combustion occurs within constant volume before the gas begins to expand.
Engines in most, if not all, embodiments of the invention described herein can run using various cycles including HEHC, modified HEHC (when combustion occurs at isochoric conditions first and isobaric condition second, and/or Homogeneous Charge Stimulated Ignition (HCSI), described below. Moreover, if high pressure fuel injectors are used, it is possible to switch between these cycles on the “fly” during the operation of the engine.
Thus in a further embodiment of the present invention, Engine 1000 is configured to execute the HEHC, described in our published patent application WO 2005/071230, which is hereby incorporated herein by reference. The compressed working medium, which may be stored in an intermediary buffer at ˜50 to 70 bar pressure or above, is admitted to a completely enclosed constant volume working chamber, formed during first angular range of the cycle, and containing exhaust gases from the previous cycle at ambient pressure. Working medium, which may be air, for example, is admitted into this combustion chamber through air valve assembly, 118 of
The fuel injection may continue through the second angular range (expansion stage), i.e. within expansion chamber 208. In this phase, the engine will demonstrate diesel-like performance with the exception of a higher expansion ratio (Atkinson cycle)—for that reason, we call this cycle a modified HEHC.
In addition to HEHC or modified HEHC cycles, most, if not all, embodiments of the invention described herein can run, what we call a Homogeneous Charge Stimulated Ignition (HCSI), which is a variation of known Homogeneous Charge Compression Ignition (HCCI).
In HCCI engines a lean fuel/air mix is compressed to high compression ratio (˜18 to 20) within the cylinder of the engine. Since the fuel is already well pre-mixed within the combustion chamber in HCCI engines, it forms a homogeneous charge, which then ignites due to an increase in temperature due to compression—hence the name HCCI. Unlike the Otto engine, one can compress to such a high ratio here due to the use of a very lean fuel/air mix. On the other hand, unlike a Diesel engine, the combustion is very rapid, almost instantaneous, and thus occurs at nearly constant volumes. These engines have high efficiencies and may run on any fuel. An essential requirement for these engines, as is true for any reciprocating piston engines is that ignition has to occur at or near the Top Dead Center (TDC), a criterion that creates a very difficult problem in controlling the exact moment of ignition, as it depends on a great many parameters such as fuel to air ratio, compression ratio, air temperature and humidity, EGR rate, cylinder wall temperature, etc., etc. For this reason, engines of this design are not commercialized. Also, due to the lean mixture, the power density is low. (One is not using all the air in the mix, so for the same power one needs a bigger cylinder volume.)
In contrast, engines in accordance with embodiments of the invention herein described can be considered to work on a variation of the HCCI principle, but use of the distinctive engine geometry makes the time of ignition much less critical, as will be explained below. When compressed working medium (air) is injected into the combustion chamber from the intermediary buffer, it is initially decompressed (and cooled) and then recompressed (and re-heated) when pressure in the combustion chamber reaches the pressure of the intermediary buffer. Due to the very large pressure difference between the intermediary buffer and the combustion chamber, which is initially at ambient pressure, a supersonic swirl or vortex of rotating air, which rotates at very large rate (1,000,000 RPM or above), is formed by the air entering the combustion chamber. The fuel, injected simultaneously with air into a low pressure environment, will be dragged into the chamber by the air swirl, mix very well with the air and evaporate very quickly, if it is a liquid fuel. The fuel supply is then cut off by the fuel valve assembly 318 from the signal generated by controller 319, while air continues to fill the combustion chamber and keeps increasing the pressure. Therefore, unlike a conventional reciprocating piston engine, which compresses the air by moving a piston, HCRE engine compresses the air/fuel mixture by the air itself. When temperature and pressure reach the auto-ignition point, the fuel is going to ignite within the whole volume, in a manner similar to HCCI engines. At this point of time, pressure buildup in the combustion chamber causes the check-valve of the air valve assembly 118 to close, followed by closing of a secondary air valve as a result of actuation by controller 319. Thus the energy losses associated with decompression and recompression of air entering the combustion chamber, which, incidentally, constitute only about 0.5%, per our calculations, are converted into a high efficiency fuel/air mixer. This circumstance makes it possible to run an HCRE operating under an HCSI cycle at a high rpm rates, a performance not achievable by Diesel engines.
It is furthermore possible to accelerate the ignition event by utilizing all the same means that are used in HCCI engines such as fuel to air ratio, compression ratio, air temperature and humidity, EGR rate, cylinder wall temperature, etc, and also by adding additional control means such as relative timing of air and fuel injections, presence of catalyst within the combustion chamber, etc.
Moreover, it can be seen from this description that the check valve automatically causes the air supply to be cut off at precisely the moment when pressure in the combustion chamber exceeds pressure in the compressed air supply. This circumstance, coupled with an engine geometry that dispenses with the need (in a conventional piston engine) for critical synchronization of combustion with top dead center of the piston, eliminates the need for complex calculation of the point of combustion. Furthermore, in embodiments of the present invention, the fuel/air mixture is formed during the admission of air into the working chamber and is at temperatures below auto-ignition. Thus unlike HCCI engines, in which timing of combustion depends critically on position of the piston in the cylinder, in embodiments of the present invention, engine geometry matters little, so combustion can occur at or near the point of air and fuel injections, which are always at our control, at a point in the cycle when other conditions have been optimized.
Performance characteristics of the cycle are shown in
Several other possible variations on the design of PGM 200 are now described with reference to
In another variation, two blades 256 could be used that are parallel but not collinear, as shown in
A variation (not shown) uses standalone combustion chambers 225, similar to those used in our published application WO 2005/071230, incorporated herein by reference. A potential advantage of this approach is that combustion time could be extended by utilizing two, three or more combustion cavities 225. One of these combustion cavities 225 is shown on a cutout view incorporated within the lower chamber.
An altogether different variation of engine 1000 is shown in
The expander 235 configuration of HEHC-AVRE is shown in
Expander 235 consists of: a stator ring 236, and holding vanes 237, which slides in the axial direction. It may have rollers 238 that inhibit friction between the blades and ring 236. Stator ring 236 also houses combustion chambers 240, discussed below. In addition, stator ring 236 houses exhaust ports 239, which exhaust already expanded combustion gases. These gases are pushed out by the motion and the shape of a rotary cam ring (RCR) 241, described below (see
RCR 241, driven by expanding combustion gases, rotates around the axis and drives the output shaft (and possibly the compressor). It also imparts the intermittent reciprocating axial motion to vanes 237. The key feature of RCR 241 is that it provides a dwell period to vanes 237 during which vanes 237 are stationary with respect to stator ring 236, thus forming a constant volume combustion chamber 240. During this stationary period, compressed air 305 is admitted through appropriately controlled valves (not shown) into combustion chamber 240, which is at ambient pressure at that moment. Either simultaneously with air 305 or with some delay, fuel from fuel supply 304 is injected into combustion chamber 240. Due to very turbulent swirling, fuel from fuel supply 304 is well intermixed with air 305. The mixture spontaneously ignites and combusts until completion, all while still under the dwell period or under conditions of constant volume combustion.
Vanes 237 slide inside stator ring 236. The only function of vanes 237 is to stop combustion gases from escaping the expansion chamber. Vanes 237 should have some sealing mechanism to enable this function. of the sealing mechanism may utilize Wankel-style apex and face seals or some other sealing approaches discussed in this document and in previous patent applications by these authors.
It should be noted that a number of variations of the above configuration are possible and apparent to those skilled in the art. For example, stator ring 236 may be rotary, while cam ring 241 may be stationary. Combustion chamber 240 may be formed by a cutout within vane 237, rather than within ring 236. Exhaust port 239 may be located within cam ring 241. Vanes 237 in the drawings are represented as a single body, but could consist of two or more sliding parts, supported by springs, sliding blade seals, etc.
Another variation, radically different from all of the above, is the concealed blade technology (CBT) engine. The idea behind CBT, shown as item 249 in
Still referring to
In an HCRE engine, in accordance with various embodiments of the invention described here, blade(s) move with respect to the housing walls, the bearings, the cover, and the hub. And the hub with bearings moves with respect to the housing walls and the cover. To allow for low cost manufacturing, the design of an HCRE should accommodate tolerance gaps between the various moving components on the order of 0.001″-0.003″, after thermal expansion is taken into account to allow blow-by of the engine gases. This might be acceptable if the amount of blow-by is small, as it will provide gas lubrication and some cooling to the engine blade(s), the housing and the. However, for better performance of the engine, it might be desirable for the combustion chamber and expansion chamber to be as leak free as possible while still providing lubrication and cooling. Since the moving elements within the engine have a generally rectangular cross section, special attention needs to be paid to the sealing and tribology of the engine components.
There are number of ways to seal the combustion chamber and the expansion chamber. These include abradable thermal spray coatings, apex and face sealing, water sealing, fluidic diode sealing, and strip sealing. A practical solution will be found with one or more sealing arrangements discussed below. Abradable thermal spray coatings represent the same technology used for sealing turbine blades. These coatings withstand temperatures up to 1200° C., and can be applied to a thickness of 2 mm. The blade/hub motion would chisel out a path within the coating inside the housing or the blade or the hub. The result is that the 0.001″-0.003″ manufacturing gap between the components can be reduced to almost zero, thereby reducing the leakage from the combustion chamber and the expansion chamber.
Another approach to minimizing the leakage, shown in
Still another alternative sealing arrangement could be accomplished by utilization of the water seal concept described in our published application WO 2005/071230, and elaborated herein in the context of HCRE 1000, with reference to
Water seal 311 could be applied to pivoting blade assembly 226 with or without rollers or to housing 221, in which case it can be applied directly between housing 221 and hub 227, or between housing 221 and roller 224 within housing 221, as shown in
In expander 222 from
Therefore, water in engine 1000 has sealing, cooling, lubricating and NOx reduction (as it lowers combustion chamber temperatures) functions. In addition, as was explained above, water will increase efficiency of engine 1000 since some of the energy, normally lost due to cooling losses, is returned back into the system in the form of superheated, high pressure steam.
One interesting possibility is to replace the water in the above concept with diesel or diesel-like fuels, which have better lubricity, are non-corrosive, and do not require a condensing unit. Since gaps to be closed are very small, the consumption should be insignificant. Moreover the consumption during expansion phase is useful, since vaporized fuel will be burned in combustion chamber and expansion chamber. Still another alternative is to add methanol to the water mix, which will prevent the water from freezing. The methanol will burn when it gets into combustion chamber.
We can also use a liquid in conjunction with a liquid-conduit. Water, oil, liquid fuel, etc., could be used for a liquid, while a small diameter (2-5 mm) carbon/graphite or metal mesh, made in the form of a pipe or a rope and placed within channels similar to the ones shown on
Another sealing concept that could be applicable is the fluidic diode seal. This concept was discussed at length in our published patent application WO 2005/071230, and is incorporated herein by reference.
A strip seal 316 can be used on both hub and/or blade. As shown in
The arrows in
The basic concepts underlying the design of engine 1000 can be applied to other engine configurations as well.
In
Conventional pistons can also be adapted to implement the HEHC thermodynamic cycle in a rotary engine, as shown in
Although various exemplary embodiments of the invention have been disclosed, it should be apparent to those skilled in the art that various changes and modifications can be made which will achieve some of the advantages of the invention without departing from the true scope of the invention.
The present application is a divisional application of U.S. patent application Ser. No. 11/832,483, filed Aug. 1, 2007 in the names of Alexander C. Shkolnik and Nikolay Shkolnik and entitled “Hybrid Cycle Rotary Engine”, the full disclosure of which is hereby incorporated by reference herein, and thereby also claims priority from U.S. Provisional Patent Application 60/834,919, filed Aug. 2, 2006, and U.S. Provisional Patent Application 60/900,182, filed Feb. 8, 2007, the contents of which are incorporated herein by reference.
| Number | Name | Date | Kind |
|---|---|---|---|
| 1061206 | Tesla | May 1913 | A |
| 1200133 | Reed | Oct 1916 | A |
| 1329559 | Tesla | Feb 1920 | A |
| 2522118 | Guercken | Sep 1950 | A |
| 2945619 | McLure | Jul 1960 | A |
| 3045428 | McLean | Jul 1962 | A |
| 3249095 | Hamada | May 1966 | A |
| 3297005 | Lamm | Jan 1967 | A |
| 3362633 | Freeman | Jan 1968 | A |
| 3410254 | Huf | Nov 1968 | A |
| 3422259 | Freeman | Jan 1969 | A |
| 3466002 | Freeman | Sep 1969 | A |
| 3500853 | Freeman | Mar 1970 | A |
| 3515158 | Utz | Jun 1970 | A |
| 3557813 | Fegley et al. | Jan 1971 | A |
| 3641766 | Uehling | Feb 1972 | A |
| 3899875 | Oklejas et al. | Aug 1975 | A |
| 3969039 | Shoulders | Jul 1976 | A |
| 4083663 | Montalvo | Apr 1978 | A |
| 4112977 | Syred et al. | Sep 1978 | A |
| 4311270 | Hovstadius | Jan 1982 | A |
| 4536285 | Karlsson | Aug 1985 | A |
| 4699004 | Evans et al. | Oct 1987 | A |
| 4734018 | Taniyama et al. | Mar 1988 | A |
| 4747305 | Evans et al. | May 1988 | A |
| 5314318 | Hata et al. | May 1994 | A |
| 5405159 | Klein et al. | Apr 1995 | A |
| 5573029 | Freimann | Nov 1996 | A |
| 5586780 | Klein et al. | Dec 1996 | A |
| 5935424 | Dyer et al. | Aug 1999 | A |
| 7191738 | Shkolnik | Mar 2007 | B2 |
| 7909013 | Shkolnik et al. | Mar 2011 | B2 |
| 20020182054 | Entrican, Jr. | Dec 2002 | A1 |
| 20030086782 | Moorehead et al. | May 2003 | A1 |
| Number | Date | Country |
|---|---|---|
| WO 03074840 | Sep 2003 | WO |
| WO 2005071230 | Aug 2005 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20110114057 A1 | May 2011 | US |
| Number | Date | Country | |
|---|---|---|---|
| 60834919 | Aug 2006 | US | |
| 60900182 | Feb 2007 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11832483 | Aug 2007 | US |
| Child | 12939752 | US |
