Abstract:
The present invention relates to a heat engine having a housing. A generally triangular shaped rotor can drive an offset crank as it eccentrically rotates within the housing. Two inlets with valves and two exhausts are provided. The volume between each face of the rotor and the housing defines three expansion chambers. Six power cycles are provided (one by each expansion chamber times two inlets) per revolution of the rotor. Each valve controls the length of time that high pressure gas is allowed to enter each expansion chamber. The valves are controlled by a processor and close when enough pressure is supplied so that the pressures inside and outside the expansion chamber are equal when the chamber is fully expanded just prior to exhaust. Gates can provide a mechanical advantage to the rotor by reducing the amount of pressure applied to the back side of the fulcrum.

Description:
[0001]    This patent application claims priority on and the benefit of U.S. provisional application 61/485,849 filed May 13, 2011, the entire contents of which are hereby incorporated herein by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a heat engine, and in particular to a rotary style heat engine operating with increased efficiency. 
         [0004]    2. Description of the Related Art 
         [0005]    Heat energy, sometimes called thermal energy, is defines as the kinetic energy of a system&#39;s particles. Put another way, the heat energy of a system is the amount of potential energy in a system that is derived from the heat content within the system. 
         [0006]    Temperature is not the same as heat energy. Yet, temperature makes up an integral part of the ideal gas law. The ideal gas law states: 
         [0000]    
       
      
       PV=nRT  
      
     
         [0007]    Wherein: 
         [0008]    P is Pressure 
         [0009]    V is Volume 
         [0010]    n is the amount of gas 
         [0011]    R is the universal gas constant and 
         [0012]    T is temperature 
         [0013]    This ideal gas law demonstrates that temperature and pressure are directly related when the other variables are held constant. Likewise, when temperature is held constant in a closed system, the pressure and volume are inversely related. 
         [0014]    This is demonstrated as follows: 
         [0000]        P 1* V 1= P 2* V 2 
         [0015]    That is, the sum of pressure times volume stays constant in a closed system and when the temperature remains constant. 
         [0016]    It is known that pressure within a system can be used to perform work. For example, in a properly designed system, potential energy of a high pressure container can be extracted by allowing a user to convert potential energy to kinetic energy. 
         [0017]    As an example, consider a tank that is under pressure two times atmospheric pressure. The gas will rush out of the tank when a valve is opened until the pressures inside and outside of the tank equalize. Stating this differently, the gas inside the tank expands (from inside to outside the tank) until the pressures equalize. The expansion of the gas can be utilized to perform work. 
         [0018]    There have been many engine designs over the years. One design is the Wankel, engine design. The Wankel engine is a four-cycle internal combustion engine that uses a rotating rotor motion instead of reciprocating pistons. The four cycles takes place between a Reuleaux triangle shaped rotor and an epitrochoid-shaped housing. 
         [0019]    The housing can be defined as having 360 degrees of rotation. The rotor can generally be described as an equilateral triangle with rounded faces. The sum of internal angles of an equilateral triangle is 180 degrees. In this regard, the rotor revolves around an offset crankshaft wherein the apexes of the rotor contact the housing at all times. An example of this engine  5  design is shown in  FIG. 1 . 
         [0020]    A single rotor engine is considered a three cylinder engine. In this regard, the space or volume between the apexes of the triangle and the housing wall define three chambers. Each chamber acts independently of the other chambers and each undergoes the intake, compression, ignition and exhaust cycles of the four-cycle design. Hence, three power cycles are produces by this engine. 
         [0021]    The Wankel engine has been modified in many ways. Some modifications of the Wankel design, as well as examples of other designs are illustrated in the following patents and published application. 
         [0022]    U.S. Pat. No. 3,426,525 to Rubin is titled Rotary Piston External Combustion Engine. 
         [0023]    U.S. Pat. No. 3,509,718 to Fezer et al. is titled Hot Gas Machine. 
         [0024]    U.S. Pat. No. 4,206,606 to Reich is titled Rotary Stirling Cycle Engine. It discloses a rotary Stirling cycle machine comprising at least two chambers, said chambers being epitrochoidal in cross-sectional area and having an upper portion, a middle waist portion and a lower portion, with the first chamber mounted to the second chamber in tandem, each chamber having a seal element attached to the waist portion and disposed inwardly, the crank shaft rotatably mounted within the chambers and extending therethrough with the first crank throw portion within the first chamber being 180.degree. out of phase with the second crank throw portion within the second chamber, the first and second rotor elements rotatably mounted on said respective crank throw portions with each rotor element being limicon shaped in circumference and adapted to register with the upper and lower portions of the respective chambers so that the rotor elements cyclically rotate about the rotating crank shaft from a position in registration with the upper portion to a position in registration with the lower portion, said seal elements being in constant sealing engagement with the respective rotor elements to define first cavities in the upper portions and second cavities in the lower portions, and heater-regenerator-cooler means operatively connected to said first and second cavities to condition a working fluid through repeated Stirling cycles. 
         [0025]    U.S. Pat. No. 4,357,800 to Hecker is titled Rotary Heat Engine. It teaches a rotary external combustion heat engine for furnishing mechanical energy from a source of heat. The engine includes a ring-like stator having an oval rotor chamber enclosing a cylindrical rotor eccentrically placed within the chamber to define a high displacement high temperature fluid chamber and a lower displacement low temperature fluid chamber. A plurality of extensible vanes extend outwardly from the rotor in sliding contact with the inner surface of the rotor chamber. A source of heat supplies thermal energy to fluid supplied to the high temperature chamber, while a heat sink cools fluid supplied to the low temperature chamber. An economizer heat exchanger is also provided for preheating the working fluid. The relative position of the rotor within the rotor chamber is adjustable for varying the relative displacement of the fluid chambers to control engine working parameters. In another embodiment, a first heat engine is utilized as a motor and is mechanically coupled to a second heat engine utilized as a heat pump for providing an external combustion heat pump or refrigeration unit. 
         [0026]    U.S. Pat. No. 4,760,701 to David is titled External Combustion Rotary Engine. The patent describes an external combustion rotary engine comprising a motor member, a free-piston combustion member and a storage tank serving also as a heat exchanger and located between the motor and the combustor. The motor rotors rotate inside an enveloping structure eccentrically with respect to a power shaft to form alternatively compression and expansion chambers. Compressed air produced thereby is ducted first to the storage tank and then to the combustor for burning fuel to produce combusted gases which are in turn ducted to the storage tank where heat is exchanged between the hot gases and the cooler compressed air. The combusted gas is then expanded in the expansion chambers. A fraction of the compressed air is further compressed to a higher pressure level so that it may be used in air pad cushions to isolate the various engine rotating parts from the fixed structures surrounding them. The use of such air cushions prevents contacts between moving parts and eliminates friction, heat production therefrom and wear. The need for lubrication is thus also eliminated. The “externally” performed fuel combustion is much slower than in comparable internal combustion rotary engines. This results in higher combustion efficiencies, lower combustion temperatures and lower rates of production of pollutants such as NO.sub.x. 
         [0027]    U.S. Pat. No. 5,211,017 to Pusic is titled External Combustion Rotary Engine. It shows an external combustion rotary engine having a configuration which allows spatial separation of the heaters and coolers, and a process which enables rotary motion of the rotors to be performed without internal combustion. The engine includes the triangular rotors enclosed inside the housings shaped in the form of an epitrochoid curve, the heat generating units, and the heat absorbing and discharging units. The heat generating units and the heat absorbing and discharging units are located outside the housings and connected to the housings. The engine can also include the ultrasonic fuel atomizers inside the heat generating units and the turbine for the purpose of rapid acceleration. The present invention provides the simple, compact, lightweight, extremely energy-efficient and environmentally clean engine. 
         [0028]    U.S. Pat. No. 5,325,671 to Boehling is titled Rotary Heat Engine. It describes an engine energized by an external heat source and cooled by an external cooling source, driven by a closed body of gas contained in chambers of variable volume and passages connected thereto, and operating on a Carnot cycle. The apparatus of the engine also has heat pump capabilities. 
         [0029]    U.S. Pat. No. 6,109,040 to Ellison, Jr. et al. is titled Stirling Cycle Refrigerator or Engine employing the Rotary Wankel Mechanism. It illustrates a non-reciprocating Stirling-cycle machine which overcomes problems associated with high drive mechanism forces and vibration that seriously hamper reciprocating Stirling-cycle machines. The design employs Wankel rotors instead of the reciprocating pistons used in prior Stirling machines for effecting the compression and expansion cycles. Key innovations are the use of thermodynamic symmetry to allow coupling of the rotating compression and expansion spaces through simple stationary regenerators, and the coordination of thermodynamic and inertial phasing to allow complete balancing with one simple passive counterweight, which is not possible in reciprocating machines. The design can be scaled over a wide range of temperatures and capacities for use as a cryogenic or utilitarian refrigerator or to function as an external heat powered engine. 
         [0030]    United States Patent Application Publication 2009/0139227 to Nakasuka et al. is titled Rotary Heat Device. It has a rotary heat engine having a cylinder and a rotor having a rotating shaft rotatably placed in the cylinder. The cylinder has a heat receiving section for supplying heat to the inside of the cylinder and a heat radiating section for radiating heat from the inside. The engine also has an engine section body and an operation liquid storage section. A vaporized gas supply channel and a gas recovery channel communicating with the inside of the cylinder are provided, respectively, on the heat receiving section side and heat radiating section side of the cylinder in the engine section body. The operation liquid storage section is between the vaporized gas supply channel and the gas collection channel in order to aggregate and liquefy recovered gas and is installed such that both channels fluidly communicate with each other. Also, the operation liquid storage section has a heat insulation dam provided with a through hole for preventing backflow of fluid flowing inside. 
         [0031]    While each of these devices may be useful for their intended purposes, none show the unique advantages of the present invention. 
         [0032]    Specifically none show an engine utilizing an elongated driving force due to opening of a valve when one of three apexes passes a prior exhaust port and the expansion chamber volume is small. 
         [0033]    None show that an input valve can be closed at the appropriate timing whereby pressure in the expansion chamber and the pressure in the system outside of the expansion chamber will be approximately equal when the rotor leading apex passes the exhaust port. 
         [0034]    Due to the geometry of adding a second inlet and exhaust ports, modified engines suffer from blow-by at certain times. The blow-by occurs as an expansion chamber will be open to both the inlet and exhaust simultaneously. None show the use of valves to prevent blow-by in a system having three apexes of a triangular rotor and two inlets and two exhaust ports spaced about the engine housing. 
         [0035]    None show the use of fixed gates mounted in the housing to decrease expansion chamber volume and increase the portion of driving force about one side of a rotor as the rotor orbits about the housing center point. 
         [0036]    Thus there exists a need for a heat engine that solves these and other problems. 
       SUMMARY OF THE INVENTION 
       [0037]    The present invention relates to a heat engine having a housing. A generally triangular shaped rotor can drive an offset crank as it eccentrically rotates within the housing. Two inlets with valves and two exhausts are provided. The volume between each face of the rotor and the housing defines three expansion chambers. Six power cycles are provided (one by each expansion chamber times two inlets) per revolution of the rotor. Each valve controls the length of time that high pressure gas is allowed to enter each expansion chamber. The valves are controlled by a processor and close when enough pressure is supplied so that the pressures inside and outside the expansion chamber are equal when the chamber is fully expanded just prior to exhaust. Gates can provide a mechanical advantage to the rotor by reducing the amount of pressure applied to the back side of the fulcrum. 
         [0038]    According to one advantage of the present invention, the engine utilizes an elongated driving force due to opening of a valve when one of three apexes passes a prior exhaust port and the expansion chamber volume is small. The faces of the rotor are smooth and undished in order to minimize the volume in each chamber when the valve first opens. 
         [0039]    According to another advantage of the present invention, the input valve can be closed at the appropriate timing whereby pressure in the expansion chamber and the pressure in the system outside of the expansion chamber will be approximately equal when the rotor leading apex passes the exhaust port. In this regard, the efficiency of the expansion phase is maximized because all of the energy is utilized as the pressures are equalized when the system opens to the exhaust. 
         [0040]    According to further advantage of the present invention, the use of valves prevents blow-by in the system. Blow-by would otherwise occur in a system having three apexes of a triangular rotor and two inlets and two exhaust ports spaced about an engine housing since at times in the revolution of the rotor a chamber would be open to both an inlet and an exhaust port at the same time. Using a valve prevents this occurrence from happening. 
         [0041]    According to a still further advantage of the present invention, fixed gates are provided to decrease expansion chamber volume (start of the expansion) and also to increase the mechanical advantage of the rotor during the expansion (the portion of driving force about one side of a rotor as the rotor orbits about the housing center point). The side of the rotor upon which driving force acts is called the positive side of the fulcrum. Further, the undished face allows the gates to fully divide the expansion chambers into two portions due to being able to fully engage the rotor. 
         [0042]    The gates can have a selected angular alignment whereby pressure within the expansion chamber acts to force the gates against the rotor face to form a strong seal. 
         [0043]    The use of gates also allows the exhaust ports to be moved to different locations about the housing. In one embodiment, the pressure can be applied over about 30 degrees of rotation. However, by adding the gate and moving the outlet, the pressure can be applied over approximately 70 degrees of rotation, greatly increasing the driving force applied to the rotor. 
         [0044]    According to a still further advantage of the present invention, the engine has six power cycles per revolution. This is due to three expansion chambers and two inlets. Each power cycle is offset from each other, whereby the combined power curve is smoothed out. 
         [0045]    According to a still further advantage of the present invention, a processor is provided to control the opening and closing of the valves. The opening will be at a set point when the volume in the expansion chamber is at or near a minimum. The processor interprets both the input and exhaust pressures and closes the input valve at an exact time which allows for the high pressure gas entering the chamber to fully expand and be approximately equal to the pressure on the low pressure side of the system at exhaust. 
         [0046]    According to a still further advantage of the present invention, a partial vacuum can be provided as the gas cools in the condensation chamber. This lower pressure can help to pull to rotor around its rotation. 
         [0047]    Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention and studying the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0048]      FIG. 1  is a schematic view of a traditional Wankel style engine. 
           [0049]      FIG. 2A  is a schematic view of a preferred embodiment of the present invention. 
           [0050]      FIG. 2B  is similar to  FIG. 2A , but shows an additional reheat circuit between a pump and a high pressure tank. 
           [0051]      FIG. 3  shows a controller in electrical communication with a first valve and a second valve. 
           [0052]      FIG. 4  is a top view showing the rotor in selected position within the housing. 
           [0053]      FIG. 5  is a top view showing the rotor in selected position within the housing. 
           [0054]      FIG. 6  is a top view showing the rotor in selected position within the housing. 
           [0055]      FIG. 7  is a top view showing the rotor in selected position within the housing. 
           [0056]      FIG. 8  is a top view showing the rotor in selected position within the housing. 
           [0057]      FIG. 9  is a top view showing the rotor in selected position within the housing. 
           [0058]      FIG. 10  is a top view showing the rotor in selected position within the housing. 
           [0059]      FIG. 11  is a top view showing the rotor in selected position within the housing. 
           [0060]      FIG. 12  is a top view showing the rotor in selected position within the housing. 
           [0061]      FIG. 13  is a top view showing the rotor in selected position within the housing. 
           [0062]      FIG. 14  is a top view showing the rotor in selected position within the housing. 
           [0063]      FIG. 15  is a top view showing the rotor in selected position within the housing. 
           [0064]      FIG. 16A  is a chart showing Pressure vs. Volume within an expansion chamber of the present invention. 
           [0065]      FIG. 16B  is a chart showing pressure within an expansion chamber as apex A moves around the housing. 
           [0066]      FIG. 16C  is similar to  FIG. 16B , but shows an increased pressure throughout the revolution of apex A. 
           [0067]      FIG. 17  is a top view of an embodiment of the present invention including an alternative gate structure. 
           [0068]      FIG. 18  is a side view of  FIG. 17 . 
           [0069]      FIG. 19  is similar to  FIG. 18 , but shows two housings with rotors in opposed positions. 
           [0070]      FIG. 20  is an isolation perspective view of a rotor showing smooth rotor faces. 
           [0071]      FIG. 21  shows pressure being applied to ½ of the rotor, wherein an expansion chamber is bisected by a gate. 
           [0072]      FIG. 22  is a close up view showing an alternative embodiment of a gate with the rotor in a selected position. 
           [0073]      FIG. 23  is similar to  FIG. 22 , but shows the rotor in a different position. 
           [0074]      FIG. 24  is a close up view showing an alternative embodiment of a gate with the rotor in a selected position. 
           [0075]      FIG. 25  is a close up view of the gate illustrated in  FIG. 24 . 
           [0076]      FIG. 26  is similar to  FIG. 25 , but shows the rotor in a different position. 
           [0077]      FIG. 27A  is a schematic view with an apex approximately 20 degrees before top dead center. 
           [0078]      FIG. 27B  is a schematic view with an apex approximately 10 degrees before top dead center. 
           [0079]      FIG. 27C  is a schematic view with an apex approximately at top dead center. 
           [0080]      FIG. 27D  is a schematic view with an apex approximately 10 degrees after top dead center. 
           [0081]      FIG. 27E  is a schematic view with an apex approximately 20 degrees after top dead center. 
           [0082]      FIG. 27F  is a schematic view with an apex approximately 30 degrees after top dead center, wherein the bottom gate ceases to seal the bottom expansion chamber. 
           [0083]      FIG. 28  is a schematic view showing alternative inlet and exhaust locations. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0084]    While the invention will be described in connection with one or more preferred embodiments, it will be understood that it is not intended to limit the invention to those embodiments. On the contrary, it is intended to cover all alternatives, modifications and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. 
         [0085]    Looking now to  FIG. 2A , it is seen that an engine  10  is provided having a housing  20 . A rotor  60  is further provided. The rotor  60  rotates within the housing  20  as described below. 
         [0086]    A high pressure tank  120  is provided. The tank can be any suitable size. The tank  120  can hold a selected amount of working medium  130 . The working medium is preferably a commonly available refrigerant that undergoes a phase change between liquid  131  and gas  132  at predictable temperatures and pressures. One preferred refrigerant is R-123. However it is understood that other refrigerants could be used without departing from the broad aspects of the present invention. 
         [0087]    A heat source  140  is provided. The heat source  140  is in close proximity to tank  120 , whereby the heat source can heat the working medium  120  causing selected amounts of liquid  131  to undergo a phase change to gas  132 . The tank can hold the gas at high pressures. It is understood that operating pressures and temperatures are determined based on system requirements and refrigerants used. A gauge  150  is provided for measuring the pressure in the high pressure tank  120 . 
         [0088]    A high pressure delivery system  160  is provided. The high pressure delivery system  160  can be split into two lines, a first line  165  and a second line  166 . The lines are fluidly connected wherein the pressure in each line  165  and  166  are preferably the same. The high pressure delivery system  160  provides high pressure gas to the housing  20  of the engine  10 . 
         [0089]    A low pressure exhaust system  170  is further provided. The low pressure exhaust system receives low pressure exhaust from the housing  20  of the engine. The low pressure exhaust system has a first line  171  and a second line  172 . The first and second lines  171  and  172 , respectively, combine in line  173 . 
         [0090]    The low pressure exhaust  170  goes through a condensation chamber  180  having a heat exchanger  185 . The condensation chamber  180  has a gauge to measure pressure within the system on the low pressure side of the system. The condensation chamber  180  empties liquid condensate into a low pressure condensation tank  200 . From there, a pump  210  is used to route liquid  131  back into the high pressure tank  120  to repeat the cycle. 
         [0091]    Looking briefly at  FIG. 2B , it is seen that an alternative line  420  can be provided to route liquid through a heat exchanger  421  prior to entering the high pressure tank to pre-heat the liquid. 
         [0092]    A processor  230  is provided. The processor  230  communicates with position sensors or locators  240  and  241  (which monitor the location of the rotor  60  within the housing  20 ). The processor  230 , as seen in  FIG. 3 , is also in communication with valves  41  and  46 , described below. The processor controls the opening and closing of the valves  41  and  46 . 
         [0093]    Turning now to  FIGS. 4-15 , it is seen how the rotor  60  moves about the housing  20 . 
         [0094]    The housing  20  has a wall  21  with an inside surface  22 . The inside surface defines a general epitrochoid shaped structure having a first section  23  and a second section  24 . The sections are generally open to each other, but have a first radius  30  and second radius  35  there between. The radii  30  and  35  protrude a small amount toward the center of the housing  20 . The radii  30  and  35  have openings or recesses  31  and  36  respectively, to accommodate stationary gates (described below). The openings preferably span from the top to the bottom or the full dimension of the housing and are complimentary in shape to the respective gates. It is appreciated that the openings or recesses may not span the full dimension so long as they support gates that do span the entire dimension. 
         [0095]    The housing has an inlet  40  with a valve  41 , an inlet  45  with a valve  46 , an outlet  50  and an outlet  55 . The inlets  40  and  45  are spaced apart (preferably approximately 180 degrees on separate sides of the housing) and are separated by outlets  50  and  55 . The valves  41  and  46  are preferably selectably opened and closed under the direction of the processor  230  based on the location of the rotor  60  within the housing  20 . 
         [0096]    The rotor  60  is generally reuleaux shaped. In this regard, the rotor  60  has three faces, namely a first face  65 , a second face  66  and a third face  67 . The faces meet at apexes, namely the apex A  70 , apex B  71  and apex C  72 . Seals  75 ,  76  and  77  are provided respectively at apex A  70 , apex B  71  and apex C  72 . The rotor  60  is shown prospectively in  FIG. 20 . Faces  65 ,  66  and  67  are preferably smooth and are formed without cavities or other recesses therein. In this regard, the faces travel closely to the inside surface  22  of the housing. 
         [0097]    It is understood that the seals actually contact the housing, but for sake of simplicity in description, it is described herein as apex&#39;s passing certain points such as inlets and exhausts. 
         [0098]    As is best seen in  FIG. 18 , the housing  20  has a center or fulcrum  81 . The rotor has a center line  80  as well. The rotor center line  80  is offset from the fulcrum  81  a selected amount as the rotor  60  rotates in an eccentric manner about the housing  20 . The frame of reference of the viewer determines the direction of rotation. For example, staying with  FIG. 18 , the rotor rotates in a clockwise direction within the housing. However, the direction of rotation would be opposite if the field of view likewise is opposite. 
         [0099]    A first expansion chamber  90 , a second expansion chamber  100  and a third expansion chamber  110  are provided. The expansion chambers are located between the rotor  60  and the housing  20 . A driving force is provided in an expansion chamber due to the offset orientation of the fulcrum and the rotor center. 
         [0100]    It is understood, looking at  FIGS. 4-15 , that one of the expansion chambers may be exposed to either the first inlet and first outlet or the second inlet and second outlet simultaneously. However, since the first inlet and second inlet both are valved (and can be closed) blow-by is prevented in the present invention as the respective valves will be closed when the condition exists when the expansion chambers are so exposed. 
         [0101]    A gate  250  is provided and shown in  FIGS. 4-15  and  24 - 26 . Gate  250  is preferably removably received (via the top or bottom of the housing) within opening  31  of radius  30 . Gate  250  has a first end  251  pivotally held within the opening  31  and an opposed second end  252  that contacts the rotor  60  at a tip. A face  253  is provided facing the rotor  60  and a back is provided facing the inside of the opening  31 . A spring  255  is provided for biasing the gate end  252  away from the opening  31  and towards the rotor  60 . A seal  256  is provided on the rear side of the gate. Gate  250  preferably spans the entire height of the housing  20 . Gate  250  has a lip  257  that engages in inside wall of the opening to hold the gate  250  within the opening so that the gate cannot escape from the opening. 
         [0102]    A gate  260  is further provided. Gate  260  is identical to gate  250 . Gate  260  is removably received within opening  36 . 
         [0103]    As seen in  FIGS. 27A-27E , the gate  250  preferably engages the rotor from approximately 20 degrees before top dead center until approximately 20 degrees after top dead center, and lets off the rotor at approximately 30 degrees after top dead center. The gate  250  bifurcates the expansion chamber when it contacts the rotor, whereby it prevents pressure from acting on the rotor behind the gate. Bifurcation or splitting of the expansion chamber into two parts is accomplished since the rotor faces are undished so that the gates can engage the rotor. 
         [0104]    An alternative gate  450  is illustrated in  FIGS. 17 ,  22  and  23 . Gate  450  has ends  451  and  452 . Gate  450  can be a flat piece of spring steel that bends or pivots. The gate is biased to be flat, but can be bent or pivoted to contact the rotor  60 . In this embodiment, a slot or slit can form the opening in the radius and the gate  450  can be press fit or adhesively held within the opening. It is appreciated that the gate  450  projects from the housing wall in a slanted manner toward the adjacent inlet and away from the adjacent outlet. 
         [0105]    Gate  460  can be provided and is similar to gate  450 . 
         [0106]    It is understood that the portions of the gates within the housing are movable. It is preferred that the gates are movable from a first gate position wherein the gate is flush with the housing wall to other positions wherein the gate either contacts the rotor or is projected into an expansion chamber without contacting the rotor. The gates preferably are operable to rotate in the same direction as the rotor. This allows pressure to press the gates against the rotor, as well as allowing the rotor to slide over the gates. 
         [0107]    As seen in  FIG. 16 , there are three volumes, V 1 , V 2  and V 3  respectively that occur at different times for each of the three expansion chambers of the rotor  60 . 
         [0108]    V 1  is that volume occurring when an inlet valve opens. This occurs when the leading apex passes an inlet and the trailing edge passes an exhaust. 
         [0109]    V 2  occurs when the rotor advances a sufficient amount to a maximum efficiency point. The maximum efficiency point occurs when the input valve closes at a volume so that the high pressure gas entering the expansion chamber is allowed to fully expand and be equal to the pressure on the low pressure side of the system when the leading apex reaches the exhaust port and the volume is at V 3 . 
         [0110]      FIGS. 4-15  represent a full cycle of the rotor  60  within the housing  20 . The state of each expansion chamber as shown in these drawings is shown in the following table: 
         [0000]    
       
         
               
               
               
               
             
               
               
               
               
               
             
           
               
                   
                   
               
               
                   
                 Expansion 
                 Expansion 
                 Expansion 
               
               
                   
                 Chamber 1 
                 Chamber 2 
                 Chamber 3 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 FIG. 4 
                 Fully exhausted 
                 V3 
                 V1 
               
               
                   
                 FIG. 5 
                 Fully exhausted 
                 Fully exhausted 
                 V2 
               
               
                   
                 FIG. 6 
                 V1 
                 Fully exhausted 
                 V3 
               
               
                   
                 FIG. 7 
                 V2 
                 Fully exhausted 
                 Fully exhausted 
               
               
                   
                 FIG. 8 
                 V3 
                 V1 
                 Fully exhausted 
               
               
                   
                 FIG. 9 
                 Fully exhausted 
                 V2 
                 Fully exhausted 
               
               
                   
                 FIG. 10 
                 Fully exhausted 
                 V3 
                 V1 
               
               
                   
                 FIG. 11 
                 Fully exhausted 
                 Fully exhausted 
                 V2 
               
               
                   
                 FIG. 12 
                 V1 
                 Fully exhausted 
                 V3 
               
               
                   
                 FIG. 13 
                 V2 
                 Fully exhausted 
                 Fully exhausted 
               
               
                   
                 FIG. 14 
                 V3 
                 V1 
                 Fully exhausted 
               
               
                   
                 FIG. 15 
                 Fully exhausted 
                 V2 
                 Fully exhausted 
               
               
                   
                   
               
             
          
         
       
     
         [0111]    It is appreciated from studying of the above-chart that there are six power cycles per revolution of the rotor  60  within the housing  20 . 
         [0112]    As means of an example only, at V 2 , the volume can be 1 unit and the pressure 4 units. Then, at V 3 , the volume can be 4 units and the pressure 1 unit. Likewise, the pressure external of the expansion chamber is 1 unit. In this regard, the pressure inside and outside of the expansion chamber are equal at V 3 . The timing of the opening and closing of the input valves is determined by the processor whereby this result is achieved. 
         [0113]      FIG. 16B  shows graphically pressure within the first chamber as a function of the location of apex A  70  relative the housing (in degrees of rotation). 
         [0114]      FIG. 16  C shows graphically the pressure within the first chamber as a function of the location of apex A  70  with an elongated driving force due to 1) opening the valve approximately 20 degrees earlier and closing approximately 20 degrees later. Both early opening and late closing are allowed by the gate. 
         [0115]    Turning now to  FIG. 19 , it is seen that a second housing  520  and rotor  560  can be provided. The rotor  560  has a center point  580  and the housing has fulcrum  581 . The housing  520  is preferably oriented similarly as housing  20 . In this regard, the respective rotors are offset from each other, which allows an engine with two housings to drive an offset crankshaft. 
         [0116]    Turning now to  FIG. 28 , it is seen that a housing  620  is provided. The housing  620  has a rotor  630  and gates  640  and  650 . The gates allow inlets  660  and  670  and outlets  680  and  690  to be located at alternative locations about the perimeter of the housing  620 . In particular, the gates and alternative exhaust locations allow for larger exhaust volumes, which in turn allow for elongated driving forces to be applied (high pressure applied longer in the cycle so that exhaust pressures are equal). 
         [0117]    Also, the gates allow the exhaust to be much closer to the next successive inlet, as the gate prevents back-flowing within an expansion chamber as it bifurcates the expansion chamber. The inlet valves can also be opened earlier in the cycle thereby elongating the driving force. In this regard, in an embodiment without a valve, the inlet valve can be opened with the trailing apex passes the exhaust port. However, when a gate is provided, there is no way for the gas to reach the exhaust port and the valve can be opened before the trailing apex passes the exhaust port. 
         [0118]    Looking now at  FIG. 21 , it is seen that if an equilateral triangle were centered within the housing, that it would be equidistant between the inlet and outlet. Further, a center line from the top apex of the triangle to the center point of the base would pass directly through the fulcrum of the housing. If there was no gate, adding pressure at this point in rotation would lead to a locked rotor (equal pressure on each side of the fulcrum) The solutions to this problem are either 1) retarding the input until the trailing apex passes the outlet or 2) adding the gate to block gas and hence pressure from being able to act on the triangle behind the gate. Hence, all of the pressure acts on the first side of the triangle which applies a force to move the triangle in clockwise orientation. 
         [0119]    It is appreciated that the engine  10  of the present invention is able to power many types of devices. Two examples are as an automobile engine and as a means to extract energy out of an existing heating system such as a building heating system. 
         [0120]    One typical building heating system is a furnace. In this regard, the current furnace simply burns fuel and uses the waste heat to warm a building. By installing a heat engine, the fuel would still be burned, but the heat energy from said burning is used to propel the heat engine, such as the heat engine of the present invention, which can be used to generate electric power via generator. 
         [0121]    The waste heat contained in the gas exiting the exhausts is still routed through the condensation chamber  180 . Yet, heat exchanger  185  can be used to draw heat from the condensation chamber  180  and transfer it to a building via the building HVAC system. In this regard, the heat of the exhaust gas is not lost, and not dissipated generally. Instead, the dissipated heat is redirected to the building to fulfill the environmental requests of the HVAC system. 
         [0122]    Thus it is apparent that there has been provided, in accordance with the invention, a heat engine that fully satisfies the objects, aims and advantages as set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims.