Patent Publication Number: US-7913663-B2

Title: Rotary piston machine

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to rotary machines including motors, pumps and compressors, and more particularly, to a rotary piston machine having multiple seals between ends of a rotary piston member and arcuate side walls that form a cavity in the rotary piston machine. 
     2. Background of the Prior Art 
     Rotary piston machines are well known. United States Patent Application Publication US 2004/0244762, A1, presents a typical rotary piston machine with a myriad of configurations and cooperating machine members that ultimately provide rotary motion. 
     The problem with prior art rotary piston machines is that a rotating piston member forms a compression or ignition chamber via narrow edge portions of ends of the piston member engaging side walls of a cavity, thereby forming single seals with relatively small lateral dimensions between the ends of the piston member and the side walls, resulting in seals with relatively small surface areas. The small surface areas of the single seals allow a small amount of “leakage” of a fuel-air mixture from the compression chamber before ignition of the fuel-air mixture occurs, thereby reducing the power generated by the quantity of fuel-air mixture “exploded” in the compression chamber. 
     Another problem with prior art rotary piston machines is that a drive shaft or drive pin that is forcibly rotated by the piston member to ultimately drive a flywheel, is designed to follow a generally circular path with a relatively small diameter. The small diameter path reduces the amount of torque generated by the piston member when forcibly rotated by the exploding fuel-air mixture. Further, the small diameter path promotes a relatively fast piston member rotation. A relatively fast piston member rotation can result in a loss of power when the fuel-air mixture ignites, due to piston member rotation speed expanding the compression chamber at a rate that reduces the force of the ignited expanding gases upon the rotating piston member. 
     Yet another problem with prior art rotary piston machines is that the piston member includes relatively large lateral dimensions. The large lateral dimensions results in a piston member with a relatively large mass that reduces the power output from the rotary piston machine. 
     A need exists for a rotary piston machine with single or multiple seals with relatively large surface areas between each end of the rotary piston member and arcuate side walls forming the cavity of the enclosure of the rotary piston machine. Further, a need exists for a rotating piston member with a relatively small lateral dimension to reduce the mass of the piston member. Also, a need exists for a rotary piston machine with a drive pin that follows a relatively large diameter circular path relative to the diameter of the cavity of the enclosure of the machine. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to overcome many of the disadvantages associated with prior rotary piston machines. 
     A principal object of the present invention is to maintain pressure in a compression chamber of a rotary piston machine, thereby providing maximum power output upon ignition of a fuel-air mixture in the compression chamber. A feature of the rotary piston machine is one relatively large seal formed via arcuate wall portions of ends of a piston member of the rotary piston machine engaging cooperating arcuate side walls forming a cavity in an enclosure of the machine. Another feature of the machine is two relatively large seals formed via two arcuate edge portions of ends of the piston member engaging cooperating arcuate recesses in the arcuate side walls, the arcuate recesses being separated equal arcuate distances. Still another feature of the machine is a compression chambered ultimately formed via two arcuate edge portions of a first end of the piston member rotationally engaging an arcuate recess, and an arcuate wall portion of a second end of the piston member rotationally engaging an arcuate side wall to ultimately compress a gas-air mixture in the compression chamber formed via the first and second ends of the piston member engaging cooperating arcuate recesses. An advantage of the machine is that the two relatively large seals between the first end of the piston member and an arcuate recess, and the relatively large seal between the second end of the piston member and an arcuate side wall increase seal surface area and integrity, thereby preventing “leakage” of the fuel-air mixture past the first and second ends of the piston member as the piston member rotates to form the compression chamber, resulting in maximum power output from the rotary piston machine when the fuel-air mixture is ignited. 
     Another object of the present invention is to minimize the rotary force required to rotate a flywheel member of the rotary piston machine. A feature of the machine is the annular movement of a drive pin about the central axis of a flywheel, the drive pin being slidably secured to the piston member, the annular movement of the drive pin about the central axis of the flywheel including a substantially circular configuration with a relatively large diameter. An alternative feature of the machine is the annular movement of a first end of a drive rod about the central axis of the flywheel, the first end of the drive rod being slidably secured to the piston member and a second end of the drive rod being integrally joined to the flywheel, the annular movement of the first end about the central axis of the flywheel including a substantially circular configuration with a relatively large diameter. An advantage of the machine is that torque output is increased without increasing power input. Another advantage of the machine is that the circular rotation of the drive pin or the first end of drive rod promotes a relatively slow piston member movement when the piston member forms a compression chamber, thereby reducing the rate of volume increase of a compression chamber after ignition of the fuel-air mixture, and preventing the rate of volume increase of the compression chamber from reducing the amount of energy generated by an ignited and expanding fuel-air mixture or working medium. 
     Still another object of the present invention is to minimize the mass of the piston member. A feature of the machine is a piston member with a relatively small lateral dimension. An advantage of the machine is that the volume of the air-fuel mixture to be exploded in the compression chamber is maximized, thereby increasing the power generated by the machine without increasing the volume of the cavity in the enclosure. 
     Another object of the present invention is to minimize the volume of the compression chamber when the fuel-air mixture in the chamber is ignited. A feature of the machine is disposing the drive pin or the first end of the drive rod at a midpoint of the piston member when igniting the fuel-air mixture. An advantage of the machine is the prevention of the locking of the piston member during the compression and explosion sequence of the fuel-air mixture in the rotary piston machine. Another advantage of the machine is that the power output from the machine is maximized. 
     Briefly, the invention provides a rotary machine comprising an enclosure having a cavity with arcuate side walls, said arcuate side walls defining a plurality of arcuate recesses; a piston member rotationally disposed in said cavity, said piston member having end portions configured to rotationally engage said arcuate side walls and said arcuate recesses such that a compression chamber is ultimately provided between said arcuate side walls of said cavity and said piston member; means for converting piston member movement into rotary motion imparted upon a flywheel; means for supplying a working medium to predetermined portions of said cavity; means for igniting said working medium; and means for removing spent working medium from predetermined portions of said cavity, whereby, said arcuate side walls of said cavity sequentially cooperate with said piston member to provide sequential compression chambers that ultimately receive said working medium to ultimately provide rotary motion to said flywheel, which provides rotary motion to a machine via a drive shaft. 
     The invention also provides a rotary pump comprising an enclosure having a cavity with arcuate side walls, said arcuate side walls defining a plurality of arcuate recesses; a piston member rotationally disposed in said cavity, said piston member having end portions configured to rotationally engage said arcuate side walls and said arcuate recesses such that a pumping chamber is ultimately provided between said arcuate side walls and said piston member; means for imparting rotary motion upon a piston member; means for supplying a selected medium to said chamber; means for removing the selected medium from said chamber after the selected medium has been pressurized by said rotating piston member; means for providing the selected medium to a sequential pumping chamber for pressurization by said rotating piston member; and means for removing the selected medium from said sequential pumping chamber. 
     The invention further provides a method for providing a rotary piston machine, said method comprising the step of providing an enclosure having a cavity with arcuate side walls, said arcuate side walls defining a plurality of arcuate recesses; providing a piston member rotationally disposed in said cavity, said piston member having end portions configured to rotationally engage said arcuate side walls and said arcuate recesses such that a compression chamber is ultimately provided between said arcuate side walls of said cavity and said piston member; converting said piston member movement into rotary motion imparted upon a flywheel; supplying a working medium to predetermined portions of said cavity; igniting said working medium via a plurality of igniters; and removing said working medium from predetermined portions of said cavity, whereby, said arcuate side walls of said cavity sequentially cooperate with said piston member to provide sequential compression chambers that ultimately receive said working medium to ultimately provide rotary motion to said flywheel, which provides rotary motion to a machine via a drive shaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other objects, advantages and novel features of the present invention, as well as details of an illustrative embodiment thereof, will be more fully understood from the following detailed description and attached drawings, wherein: 
         FIG. 1  depicts a rotary piston member in a cavity of an enclosure, the rotary piston member is vertically disposed such that a longitudinal axis of the rotary piston member bisects a first arcuate recess, a drive pin, first and second ends of the rotary piston member, a flywheel and a second arcuate side wall opposite the first arcuate recess in accordance with the present invention. 
         FIG. 1  a depicts a second end of the drive pin secured to the flywheel. 
         FIG. 2  depicts the rotary piston member in the cavity of the enclosure of  FIG. 1 , but with the rotary piston member rotated such that the first end of the rotary piston member engages the first arcuate recess, and such that the second end of the rotary piston member engages a second arcuate recess, thereby forming a compression chamber sealed via two arcuate edges on the first end of the rotary piston member engaging cooperating portions of the first arcuate recess, and two arcuate edges on the second end of the rotary piston member engaging cooperating portions of the second arcuate recess. 
         FIG. 3  depicts the rotary piston member in the cavity of the enclosure of  FIG. 2 , but with the rotary piston member rotated such that the longitudinal axis of the rotary piston member bisects the second arcuate recess, the drive pin, first and second ends of the rotary piston member, and a third arcuate side wall opposite the second arcuate recess in accordance with the present invention. 
         FIG. 4  depicts the rotary piston member in the cavity of the enclosure of  FIG. 3 , but with the rotary piston member rotated such that the first end of the rotary piston member engages a third arcuate recess, and such that the second end of the rotary piston member engages the second arcuate recess, thereby forming a compression chamber sealed via the two arcuate edges on the first end of the rotary piston member engaging cooperating portions of the third arcuate recess, and the two arcuate edges on the second end of the rotary piston member engaging cooperating portions of the second arcuate recess. 
         FIG. 5  depicts the rotary piston member in the cavity of the enclosure of  FIG. 4 , but with the rotary piston member rotated such that the longitudinal axis of the rotary piston member bisects the third arcuate recess, the drive pin, first and second ends of the rotary piston member, and a first arcuate side wall opposite the third arcuate recess in accordance with the present invention. 
         FIG. 6  depicts the rotary piston member in the cavity of the enclosure of  FIG. 5 , but with the rotary piston member rotated such that the first end of the rotary piston member engages the third arcuate recess, and such that the second end of the rotary piston member engages the first arcuate recess, thereby forming a compression chamber sealed via the two arcuate edges on the first end of the rotary piston member engaging cooperating portion of the first arcuate recess, and the two arcuate edges on the second end of the rotary piston member engaging cooperating portions of the first arcuate recess. 
         FIG. 7  depicts the rotary piston member in the cavity of the enclosure of  FIG. 5 , but with the rotary piston member rotated to a vertical position such that the longitudinal axis of the rotary piston member bisects the first arcuate recess and the second end of the rotary piston member in the first arcuate recess, the drive pin, and the first end of the rotary piston member engaging a mid-portion of the second arcuate side wall in accordance with the present invention. 
         FIG. 8  depicts a partial view of the first end of the rotary piston member engaging the first arcuate recess of  FIG. 1 . 
         FIG. 9  depicts a partial view of the second arcuate recess of  FIG. 1 . 
         FIG. 10  depicts a partial view of the second end of the rotary piston member engaging the second arcuate side wall of  FIG. 1 . 
         FIG. 11  depicts a partial view of the first end of the rotary piston member engaging the first arcuate recess of  FIG. 2 . 
         FIG. 12  depicts a partial view of the second end of the rotary piston member engaging the second arcuate recess of  FIG. 2 . 
         FIG. 13  depicts a view of the rotary piston member removed from the cavity in the enclosure. 
         FIG. 14  depicts an alternative embodiment for the rotary drive mechanism that links the rotary piston member to the flywheel. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, a rotary piston machine in accordance with the present invention is denoted by numeral  10 . The rotary piston machine  10  can be designed to function as a motor, pump or compressor, the machine  10  including components common to all designs and well known to those of ordinary skill in the art. The rotary piston machine  10  includes an enclosure  12  having a cavity  14  therein with first, second and third arcuate side walls  16   a,b,c  defining a plurality of first, second and third arcuate recesses  18   a,b,c; , and a piston member  20  rotationally disposed in the cavity  14 . The piston member  20  includes a longitudinal slot  22  axially aligned with a longitudinal axis  24  of the piston member  20 , and first and second ends  42  and  43  configured to rotationally engage the arcuate side walls  16   a,b,c , and the arcuate recesses  18   a,b,c , such that compression chambers  26   a,b,c , are ultimately provided between the arcuate recesses  18   a,b,c , and the piston member  20 . The piston member  20  further includes a relatively small lateral dimension to minimize piston member  20  mass and to maximize a volume of a working medium that is ultimately compressed, thereby increasing power generated by the rotary machine  10  without increasing the volume of the cavity  14 . Although the rotary piston machine  10  is depicted and described throughout the specification as having three arcuate side walls  16   a,b,c , and having a piston member  20  with two ends  42  and  43 , the inventive concept included herein can be expanded to include a cavity  14  with more than three arcuate side walls and a piston member  20  configuration with more than two ends or perturbations. 
     The rotary machine  10  further includes a drive pin  28  having a first end  30  slidably secured to the piston member  20  via the longitudinal slot  22 , and a second end  32  secured to a flywheel  34 . The drive pin  28  moves lineally in alternating directions across the longitudinal slot  22 , while simultaneously moving annularly (clockwise or counter-clockwise) about a central axis  49  of the flywheel  34 . The annular movement of the drive pin  28  includes a substantially circular configuration or path with a relatively large diameter, thereby minimizing the rotary force required to rotate the flywheel  34 . The annular movement of the drive pin  28  promotes a relatively slow piston member  20  movement when the piston member  20  is disposed adjacent to the arcuate side walls  16   a,b,c , of the cavity  14 , thereby reducing the rate of volume increase of compression chambers  26   a,b,c , after ignition of the working medium in the compression chambers  26   a,b,c , and increasing the amount of power generated by an expanding working medium. 
     The configuration and dimensions of the piston member  20 , including the relatively small lateral dimension of the piston member  20 , cooperate with the dimensions of the drive pin  28  and the diameter of the circular path “traveled” by the drive pin  28  to achieve a preselected power output specification for the rotary piston machine  10 , while minimizing the cost to construct the machine  10 . The selected configurations and dimensions of the piston member  20  and drive pin  28  specified to achieve the required power output are determined via computer simulation well known to those of ordinary skill in the art. 
     The drive pin  28  cooperates with the rotary movement of the piston member  20  to provide rotary motion to the flywheel  34  via an edge portion  35  of the drive pin  28  slidably and rotationally engaging a cooperating channel portion  37  of the piston member  20 . A working medium (not depicted) such as a combination of air and fuel (gas or diesel fuel, for example) is supplied to a compression chamber  26   a , (see  FIG. 2 , the only figure depicting valves and spark plugs) via one or more intake valves  36   a . One or more spark plugs  38   a  or similar ignitor components are provided for initiating an “explosion” of the working medium within the compression chamber  26   a . One or more exhaust valves  40   a , is provided for removing spent working medium (not depicted) from the compression chamber  26   a , whereby the arcuate side walls  16   a,b,c , of the cavity  14  sequentially cooperate with the piston member  20  to provide sequential compression chambers  26   a,b,c , that ultimately receive, explode and remove the working medium via intake valves  36   a , 63   b , 36   c , spark plugs  38   a , 38   b , 38   c , and exhaust valves  40   a , 40   b , 40   c , to ultimately provide rotary motion to the flywheel  34 , which imparts rotary motion to a machine (not depicted) via a drive shaft (not depicted). Each one of the intake valves  36   a , 36   b , 36   c , spark plugs  38   a , 38   b , 38   c  and exhaust valves  40   a , 40   b , 40   c , are operated once during each rotation of the drive shaft. Configurations and placement of the intake valves  36   a , 36   b , 36   c , spark plugs  38   a , 38   b , 38   c , and exhaust valves  40   a , 40   b , 40   c , through the side walls  16   a,b,c , may vary a myriad of ways, including but not limited to replacing the intake and exhaust valves  36   a , 36   b , 36   c , and  40   a , 40   b , 40   c , with ports; and disposing an intake valve  36   a , 36   b , 36   c , adjacent to a first edge portion  50   a,b,c , of each of the arcuate recess  18   a,b,c , disposing a corresponding exhaust valve  40   a , 40   b , 40   c  adjacent to a second edge portion  52   a,b,c , of each recess  18   a,b,c , and disposing spark plugs  38   a , 38   b , 38   c , at midpoints in each arcuate side wall  16   a,b,c . Further, the rotary machine  10  may be designed to include only one intake valve  36   a , 36   b , 36   c , one spark plug  38   a , 38   b , 38   c , and one exhaust valve  40   a , 40   b , 40   c , through one arcuate side wall  16   a,b,c , thereby simplifying the design of the machine  10  but reducing the number of power “strokes” from three to one for every one hundred and eighty degrees of piston member  20  rotation or three hundred and sixty degrees of flywheel  34  rotation. 
     Referring to  FIG. 14 , an alternative embodiment for the piston member  20 -drive pin  28  communication is depicted. The alternative embodiment includes a drive rod  64  having first and second ends  66  and  68  with means (well known to those of ordinary skill in the art) to secure the first end  66  to an edge portion  69  of an annular plate  70 , which is rotationally disposed (via means well known to those or ordinary skill in the art) in an aperture  72  in a central portion of the piston member  20 . The second end  68  of the drive rod  64  is secured to a central portion of the flywheel  34 . The first end  66  of the drive rod  64  moves clockwise or counter-clockwise about the aperture  72  and with the same rotation as the flywheel  34 . The drive rod  64  responds to the rotary movement of the piston member  20  to provide rotary motion to the flywheel  34 . 
     The enclosure  12 , piston member  20 , drive pin  28 , drive rod  64  and flywheel  34  are fabricated from carbon steel or similar durable material well known to those of ordinary skill in the art. The enclosure  12 , cavity  14 , piston member  20  and flywheel  34  are dimensioned and configured including cooperating axial specifications to provide preselected power parameters when the rotary piston machine  10  is used as a motor, or preselected volume quantities when the rotary machine  10  is used as a pump or a compressor via specification means well known to those or ordinary skill in the art. 
     The arcuate recesses  18   a,b,c , are separated substantially about one-hundred and twenty degrees about the cavity  14 . The arcuate recesses  18   a,b,c , have equal and relative small degrees of arc when compared to the arcuate side walls  16   a,b,c , of the cavity  14 . The arcuate recesses  18   a,b,c , are configured and dimensioned to snugly receive first and second ends  42  and  43  of the rotating piston member  20  such that a relatively small “gap” is maintained between inner arcuate walls  56   a,b,c , of the arcuate recesses  18   a,b,c , and first and second arcuate edge portions  44  and  46  of the first and second ends  42  and  43 . The first and second ends  42  and  43  include arcuate wall portions  48  disposed between the first and second arcuate edge portions  44  and  46 . The arcuate wall portions  48  are configured and dimensioned to be congruently disposed adjacent to cooperating arcuate side walls  16   a,b,c , of the cavity  14  such that a relatively small gap is maintained between the arcuate side walls  16   a,b,c , and the arcuate wall portions  48 . The “gaps” between the first and second ends  42  and  43  of the rotating piston member  20 , and the arcuate side walls  16   a,b,c , and arcuate recess  18   a,b,c , are ultimately “filled” with oil or similar sealing lubricant, well known to those of ordinary skill in the art, to prevent compressed fuel-air mixtures from leaking from compression chambers  26   a,b,c , ultimately formed by the rotating piston member  20 . 
     The radius of arc is the same for each arcuate recess  18   a,b,c , but the dimension of the radius of arc may vary pursuant to the compression parameters of the fuel-air mixture in the compression chambers  26   a,b,c , at the moment of ignition. The greater the required compression of the fuel-air mixture, the greater the degree of arc for the arcuate recesses  18   a,b,c , and the first and second arcuate edges  44  and  46  of the ends  42  and  43  of the piston member, thereby providing larger area of engagement between the ends  42  and  43  and the arcuate recesses  18   a,b,c  to prevent the fuel-air mixture from “leaking” from the compression chamber  26 . The smaller the compression of the fuel-air mixture, the smaller the degree of arc of the arcuate recesses  18   a,b,c , and the first and second arcuate edges  44  and  46  of the ends  42  and  43 . The “volume” of the arcuate recesses  18   a,b,c , is maintained relatively small compared to the volume of the cavity  14  to maintain a relatively small gap  54  between the ends  42  and  43  and cooperating inner arcuate walls  56  of the arcuate recesses  18   a,b,c , thereby preventing “leakage” of a compressed fuel-air mixture from the compression chambers  26   a,b,c , past the two seals formed by the arcuate edges  44  and  46  engaging cooperating arcuate recesses  18   a,b,c.    
     Irrespective of the preselected dimensions for the compression chambers  26   a,b,c , the configurations of the first and second edge portions  44  and  46  of the first end  42  include a radius of circular arc with a center  61  at the first end  42 . The configuration of the arcuate wall portion  48  of the first end includes a radius of circular arc with a center  62  at the second end  43 . The configurations of the first and second edge portions  44  and  46  of the second end  43  include a radius of circular arc with a center  62  at the second end  43 . The configuration of the arcuate wall portion  48  of the second end includes a radius of circular arc with a center  61  at the first end  42 . The radius of circular arc of the first and second edge portions  44  and  46  of the first and second ends  42  and  43  is slightly less than the radius of circular arc of the arcuate recesses  18   a,b,c , to provide a relatively small gap between the first and second ends  42  and  43 , and the arcuate recesses  18   a,b,c . The radius of circular arc of the arcuate wall portions  48  of the first and second ends  42  and  43  is slightly less than the radius of circular arc of the arcuate side walls  16   a,b,c , to provide a relatively small gap between the first and second ends  42  and  43 , and the arcuate side walls  16   a,b,c . The configurations and dimensions of the first and second ends  42  and  43 , arcuate side walls  16   a,b,c , and the arcuate recesses  18   a,b,c , cooperate to provide substantially congruent positioning between cooperating and separated surfaces at all times as the piston member  20  rotates within the cavity  14 . 
     The cavity  14  is configured by disposing an arcuate recesses  18   a,b,c , between arcuate side walls  16   a,b,c . The recesses  18   a,b,c , include first and second edge portions  50   a,b,c , and  52   a,b,c  with discontinuity edges  51  which provide a “non-smooth” or discontinuous transition between an arcuate side wall  16   a,b,c , and an arcuate recess  18   a,b,c . The discontinuity edges  51  snugly insert into cooperating discontinuity recesses  53  disposed between the first and second ends  42  and  43 , and the arcuate wall portion  60  of the rotating piston member  20 , resulting in compression chambers  26   a,b,c , with smaller volumes and higher compression ratios, and seals with larger surface areas formed by cooperating portions of the arcuate recesses  18   a,b,c , and portions of the ends  42  and  43  of the piston member  20 . The increased surface area of the seals promote “tighter” compression chambers  26   a,b,c , that prevent the relatively higher compressed air-fuel mixtures therein from leaking from the compression chambers  26   a,b,c.    
     Referring to  FIG. 1 , in operation, the piston member  20  is rotating counter-clockwise about a piston member first end center  61 , resulting in a relatively slow rotation of the first end  42  of the piston member  20  about the inner arcuate wall  56   a , of the first arcuate recess  18   a , and a relatively fast movement of the second end  43  of the piston member  20  about the second arcuate side wall  16   b , of the cavity  14 . The first arcuate edge portion  44  of the first end  42  of the piston member  20  is depicted engaging a second edge  52   a , of the first arcuate recess  18   a , and the second arcuate edge portion  46  is depicted engaging a first edge portion  50   a , of the first arcuate recess  18   a , thereby providing two seals with relatively large surface areas between the first end  42  and the inner arcuate wall  56   a , of the first arcuate recess  18   a . The arcuate wall portion  48  of the second end  43  of the rotating piston member  20  is depicted cooperatively engaging the second arcuate side wall  16   b , of the cavity  14 , thereby providing a seal with a relatively large surface area between the second end  43  and the second arcuate side wall  16   b.    
     The two relatively large seals of the first end  42  and the large surface area seal of the second end  43  prevent the “leaking” of a fuel-air mixture past the first and second ends  42  and  43 , while the rotating piston member  20  compresses the fuel-air mixture supplied to the cavity  14  via intake valves  36   a . The piston member  20  continues rotating until the second end  43  of the piston member  20  engages the second arcuate recess  18   b , and the fuel-air mixture is compressed to a predetermined pressure. In the event that a relatively small quantity of fuel-air mixture should leak past the seal formed by the second arcuate edge portion  46  of the first end  42  and the first edge portion  50   a , of the first arcuate recess  18   a , during compression of the fuel-air mixture, the “leakage” quantity will be “vented” to and ultimately burned in compression chambers  26   b  formed during the operation of the rotary piston machine  10 . 
     Referring to  FIG. 2 , the second end  43  of the piston member  20  has rotated counter-clockwise about the piston member first end center  61 , such that the second end  43  of the piston member  20  engages the second arcuate recess  18   b; , whereupon, the piston member  20  rotation stops momentarily, the center of rotation of the piston member  20  changes to a piston member second end center  62 , the first arcuate edge portion  44  of the first end  42  disengages from the second edge portion  52   a , of the first arcuate recess  18   a , to allow the arcuate wall portion  48  of the first end  42  to ultimately engage the third arcuate side wall  16   c , of the cavity  14 , and the entire surface of the second arcuate edge portion  46  of the first end  42  engages the first edge portion  50   a , of the first arcuate recess  18   a , thereby providing a relatively small gap  54   a , between arcuate wall portion  48  of the first end  42  and inner arcuate wall  56   a , of the first arcuate recess  18   a , while providing a relatively large seal area between the second arcuate edge portion  46  of the first end  42  and the first arcuate recess  18   a . Further, when the piston member  20  momentarily stops rotation, the entire surface of the first arcuate edge portion  44  of the second end  43  engages the second edge portion  52   b , of the second arcuate recess  18   b , and the second arcuate edge portion  46  of the second end  43  remains disengaged from the first edge portion  50   b , of the second arcuate recess  18   b , thereby providing a relatively small gap  58   b , between the second end  43  and an inner arcuate wall  56   b , of the second arcuate recess  18   b , and forming a compression chamber  26   a , with a compressed fuel-air mixture therein pressurized to a predetermined magnitude between an arcuate wall portion  60  of the rotating piston member  20  and a corresponding first arcuate side wall  16   a , of the cavity  14 . 
     The compression chamber  26   a , volume is minimized and the fuel-air mixture pressure maximized when the drive pin  28  is disposed at a midpoint of the piston member  20  and the first and second ends  42  and  43  of the piston member  20  engage the first and second arcuate recesses  18   a , and b, thereby preventing the piston member  20  from locking during the compression and explosion sequence of the compression chamber  26   a . Spark plugs  38   a , then ignite the fuel-air mixture causing an “explosion” of the fuel-air mixture, resulting in the continuation of the forcible rotation of the piston member  20  in a counter-clockwise motion. The spent fuel-air mixture is ultimately removed from the cavity  14  via exhaust valves  40   a.    
     Referring to  FIG. 3 , the piston member  20  has continued a counter-clockwise rotation about the second end center  62 , resulting in a relatively slow rotation of the second end  43  of the piston member about the inner arcuate wall  56   b , of the second arcuate recess  18   b , and a relatively fast movement of the first end  42  of the piston member  20  about the third arcuate side wall  16   c  of the cavity  14 . The first arcuate edge portion  44  of the second end  43  of the piston member  20  is depicted engaging a second edge  52   b , of the second arcuate recess  18   b , and the second arcuate edge portion  46  is depicted engaging a first edge portion  50   b , of the second arcuate recess  18   b,  thereby providing two seals between the second end  43  and the inner arcuate wall  56   b , of the first arcuate recess  18   a . The arcuate wall portion  48  of the first end  42  of the rotating piston member  20  is depicted cooperatively engaging the third arcuate side wall  16   c , of the cavity  14 , thereby providing a seal with a relatively large surface area between the first end  42  and the third arcuate side wall  16   c.    
     The two relatively large seals of the second end  43  and the large surface area seal of the first end  42  prevent the “leaking” of a fuel-air mixture past the first and second ends  42  and  43 , while the rotating piston member  20  compresses the fuel-air mixture supplied to the cavity  14  via intake valves  36   b . The piston member  20  continues rotating until the first end  42  of the piston member  20  engages the third arcuate recess  18   c , and the fuel-air mixture is compressed to a predetermined pressure. In the event that a relatively small quantity of fuel-air mixture should leak past the seal formed by the first arcuate edge portion  44  of the second end  43  and the second edge portion  52   b , of the second arcuate recess  18   b , during compression of the fuel-air mixture, the “leakage” quantity will be “vented” to and ultimately burned in compression chamber  26   c  formed during the operation of the rotary piston machine  10 . 
     Referring to  FIG. 4 , the first end  42  of the piston member  20  has rotated counter-clockwise about the piston member second end center  62 , such that the first end  42  of the piston member  20  engages the third arcuate recess  18   c; , whereupon, the piston member  20  rotation stops momentarily, the center of rotation of the piston member  20  changes back to the piston member first end center  61 , the first arcuate edge portion  44  of the second end  43  disengages from the second edge portion  52   b , of the second arcuate recess  18   b , to allow the arcuate wall portion  48  of the second end  43  to ultimately engage the first arcuate side wall  16   a , of the cavity  14 , and the entire surface of the first arcuate edge portion  44  of the first end  42  engages the second edge portion  52   c , of the third arcuate recess  18   c , thereby providing a relatively small gap  58   b , between the second end  43  and inner arcuate wall  56   b , of the second arcuate recess  18   b , and providing a relatively large seal area between the second end  43  and the second arcuate recess  18   b . Further, when the piston member  20  momentarily stops rotation, the entire surface of the first arcuate edge portion  44  of the first end  42  engages the second edge portion  52   c , of the third arcuate recess  18   c , and the second arcuate edge portion  46  of the first end  42  remains disengaged from the first edge portion  50   c , of the third arcuate recess  18   c , thereby providing a relatively small gap  54   c , between the first end  42  and an inner arcuate wall  56   c , of the third arcuate recess  18   c , and forming a compression chamber  26   b , with a compressed fuel-air mixture therein pressurized to a predetermined magnitude between an arcuate wall portion  60  of the rotating piston member  20  and a corresponding second arcuate side wall  16   b , of the cavity  14 . 
     The compression chamber  26   b , volume is minimized and the fuel-air mixture pressure maximized when the drive pin  28  is disposed at a midpoint of the piston member  20  and the first and second ends  42  and  43  of the piston member  20  engage the second and third arcuate recesses  18   b , and c, thereby preventing the piston member  20  from locking during the compression and explosion sequence of the compression chamber  26   b . Spark plugs  38   b , then ignite the fuel-air mixture causing an “explosion” of the fuel-air mixture, resulting in the continuation of the forcible rotation of the piston member  20  in a counter-clockwise motion. The spent fuel-air mixture is ultimately removed from the cavity  14  via exhaust valves  40   b.    
     Referring to  FIG. 5 , the piston member  20  has continued a counter-clockwise rotation about the first end center  61 , resulting in a relatively slow rotation of the first end  42  of the piston member  20  about the inner arcuate wall  56   c , of the third arcuate recess  18   c , and a relatively fast movement of the second end  43  of the piston member  20  about the first arcuate side wall  16   a , of the cavity  14 . The first arcuate edge portion  44  of the first end  42  of the piston member  20  is depicted engaging a second edge  52   c , of the third arcuate recess  18   c , and the second arcuate edge portion  46  is depicted engaging a first edge portion  50   c , of the third arcuate recess  18   c , thereby providing two seals between the first end  42  and the inner arcuate wall  56   c , of the third arcuate recess  18   c . The arcuate wall portion  48  of the second end  43  of the rotating piston member  20  is depicted cooperatively engaging the first arcuate side wall  16   a , of the cavity  14 , thereby providing a seal with a relatively large surface area between the second end  43  and the first arcuate side wall  16   a.    
     The two relatively large seals of the first end  42  and the large surface area seal of the second end  43  prevent the “leaking” of a fuel-air mixture past the first and second ends  42  and  43 , while the rotating piston member  20  compresses the fuel-air mixture supplied to the cavity  14  via intake valves  36   c . The piston member  20  continues rotating until the second end  43  of the piston member  20  engages the first arcuate recess  18   a , and the fuel-air mixture is compressed to a predetermined pressure. In the event that a relatively small quantity of fuel-air mixture should leak past the seal formed by the first arcuate edge portion  44  of the first end  42  and the second edge portion  52   c , of the third arcuate recess  18   c , during compression of the fuel-air mixture, the “leakage” quantity will be “vented” to and ultimately burned in compression chamber  26   a  formed during the operation of the rotary piston machine  10 . 
     Referring to  FIG. 6 , the second end  43  of the piston member  20  has rotated counter-clockwise about the piston member first end center  61 , such that the second end  43  of the piston member  20  engages the first arcuate recess  18   a ; whereupon, the piston member  20  rotation stops momentarily, the center of rotation of the piston member  20  changes back to the piston member second end center  62 , the first arcuate edge portion  44  of the first end  42  disengages from the second edge portion  52   c , of the third arcuate recess  18   c , to allow the arcuate wall portion  48  of the first end  42  to ultimately engage the second arcuate side wall  16   b , of the cavity  14 , and the entire surface of the first arcuate edge portion  44  of the second end  43  engages the second edge portion  52   a , of the first arcuate recess  18   a , thereby providing a relatively small gap  54   c , between the first end  42  and inner arcuate wall  56   c , of the third arcuate recess  18   c , and providing a relatively large seal area between the first end  42  and the third arcuate recess  18   c . Further, when the piston member  20  momentarily stops rotation, the entire surface of the first arcuate edge portion  44  of the second end  43  engages the second edge portion  52   a , of the first arcuate recess  18   a , and the second arcuate edge portion  46  of the second end  43  remains disengaged from the first edge portion  50   a , of the first arcuate recess  18   a , thereby providing a relatively small gap  54   c , between the first end  42  and an inner arcuate wall  56   c , of the third arcuate recess  18   c , and forming a compression chamber  26   c , with a compressed fuel-air mixture therein pressurized to a predetermined magnitude between an arcuate wall portion  60  of the rotating piston member  20  and a corresponding second arcuate side wall  16   b , of the cavity  14 . 
     The compression chamber  26   c , volume is minimized and the fuel-air mixture pressure maximized when the drive pin  28  is disposed at a midpoint of the piston member  20  and the first and second ends  42  and  43  of the piston member  20  engage the third and first arcuate recesses  18   c , and a, thereby preventing the piston member  20  from locking during the compression and explosion sequence of the compression chamber  26   c . Spark plugs  38   c , then ignite the fuel-air mixture causing an “explosion” of the fuel-air mixture, resulting in the continuation of the forcible rotation of the piston member  20  in a counter-clockwise motion. The spent fuel-air mixture is ultimately removed from the cavity  14  via exhaust valves  40   c.    
     Referring to  FIG. 7 , the piston member  20  has continued a counter-clockwise rotation about the second end center  62 , resulting in a relatively slow rotation of the second end  43  of the piston member  20  about the inner arcuate wall  56   a , of the first arcuate recess  18   a , and a relatively fast movement of the first end  42  of the piston member  20  about the second arcuate side wall  16   b  of the cavity  14 . The first arcuate edge portion  44  of the second end  43  of the piston member  20  is depicted engaging a second edge portion  52   a , of the first arcuate recess  18   a , and the second arcuate edge portion  46  is depicted engaging a first edge portion  50   a , of the first arcuate recess  18   a , thereby providing two seals between the second end  43  and the inner arcuate wall  56   a , of the first arcuate recess  18   a . The arcuate wall portion  48  of the first end  42  of the rotating piston member  20  is depicted cooperatively engaging the second arcuate side wall  16   b , of the cavity  14 , thereby providing a seal with a relatively large surface area between the first end  42  and the second arcuate side wall  16   b.    
     The two relatively large seals of the second end  43  and the large surface area seal of the first end  42  prevent the “leaking” of a fuel-air mixture past the first and second ends  42  and  43 , while the rotating piston member  20  compresses the fuel-air mixture supplied to the cavity  14  via intake valves  36   a . The piston member  20  continues rotating until the first end  42  of the piston member  20  engages the second arcuate recess  18   b , and the fuel-air mixture is compressed to a predetermined pressure. In the event that a relatively small quantity of fuel-air mixture should leak past the seal formed by the first arcuate edge portion  44  of the second end  43  and the second edge portion  52   a , of the first arcuate recess  18   a , during compression of the fuel-air mixture, the “leakage” quantity will be “vented” to and ultimately burned in compression chamber  26   a , formed during the operation of the rotary piston machine  10 . 
     The rotation of the piston member  20  depicted in  FIGS. 1-7  is one hundred and eighty degrees, while the rotation of flywheel  34  is three hundred and sixty degrees. The cycle of the rotary piston machine  10  is then repeated as depicted in  FIGS. 1-7 , however, the positions of the first and second ends  42  and  43  of the piston member  20  are reversed relative to all the figures. 
     The foregoing description is for purposes of illustration only and is not intended to limit the scope of protection accorded this invention. The scope of protection is to be measured by the following claims, which should be interpreted as broadly as the inventive contribution permits.