Abstract:
A family of sliding vane rotary power devices provides an internal combustion engine, a pump, a compressor, a fluid-driven motor, an expander device, a fluid-driven pump, and a compressor or a throttling device. All of these devices have an improved method of vane actuation comprising a freely sliding element partially enclosed by a medially extended outer vane portion and partly enclosed at its ends by a mirror-image encircling cam groove formed in a circumferentially-split external housing. As the rotor turns, the sliding elements engage the encircling extended vane portion and the mirror-image cam grooves cause the vanes to reciprocate radially in respective rotor slots while the outer vane tips follow the wall contour of the rotor with a minimal clearance so that the cavities rotate with the rotor and expand and contract as the rotor turns. Various devices in the family of devices differ both in the configuration of an internal stator member about which the rotor assembly turns and in the disposition of ports.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation-in-part of the inventor&#39;s U.S. patent application having Ser. No. 10/192,176, which was filed on Jul. 10, 2002. The disclosure of application Ser. No. 10/192,176 is herein incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to sliding vane rotary power devices, and more particularly to internal combustion engines, pumps, compressors, fluid-driven motors, expander devices, fluid-driven pumps and compressors, where various ones of those devices differ from others by a simple modification of a central stator member. 
     BACKGROUND OF THE INVENTION 
     This invention relates to a rotary power device of the radial sliding vane type. These types of devices are characterized in having a rotor assembly comprising a number of vanes equally spaced about the rotor so as to divide the rotor chamber into discrete cavities. As the rotor turns, the vanes follow the wall contour of the rotor chamber and thereby provide cavities that rotate with the rotor. The rotor chamber has an axis that can be concentric or eccentric with respect to the axis of the rotating member. This invention belongs to the former type in which the axis of the substantially oval-shaped chamber coincides with the axis of rotation and the chamber comprises two diametrically opposed quadrants of expanding cavities that are alternated by another two quadrants of contracting cavities. In a typical four-cycle engine the processes of intake, compression, power and exhaust are distributed equally among the four quadrants. Additionally, the sliding vane device of the present invention can be configured to operate as a double-action pump or compressor, an expander device, a fluid-driven pump or compressor and a two-cycle internal combustion primarily through the replacement of a central stationary member and a rearrangement of exhaust ports. 
     Sliding vane rotary devices generally comprise straight vanes slidably received within respective slots radially formed in a rotor. As the rotor spins, vanes are driven outward by centrifugal forces to an extent constrained by the wall contour, and execute radially reciprocating motion as the rotor spins. In an effort to reduce vane tip loading and increase outward radial movement response, a variety of vane actuation methods have been developed. One class of devices employs a biasing spring disposed at the base of the vane. Another class uses a pair of controlling sidewall cam grooves engaged by sub-shafts fixed to lower side portions of a vane. Still another class uses a transfer passage connecting a pressurized fluid to the base of the vanes. Although the functionality of such means of vane actuation have been proven, they are characterized in some respects with excessive friction, fluid slip, leakage, and complexity. Examples of rotary devices of the above type can be found in various United States patents such as U.S. Pat. No. 6,030,195 to Pingston; U.S. Pat. No. 4,355,965 to Lowther; U.S. Pat. No. 5,415,141 to McCann; U.S. Pat. No. 4,353,337 to Rosaen; and U.S. Pat. No. 4,018,191 to Lloyd. 
     SUMMARY OF THE INVENTION 
     The present invention provides a rotary power device that can be configured, among other things, to serve as a two or a four cycle internal combustion engine, a motor-driven pump or compressor, a fluid driven pump or a compressor by replacing a stationary central member. Preferred embodiments of the invention comprise a toroidal block rotor assembly having a centrally bored portion. This rotor assembly may be fixedly secured to an end shaft and rotatably carried at one end of an external stator housing. The central bored portion of the rotor communicates with a plurality of radially disposed open-ended compartments. The radial compartments are disposed alternatively along the circumference of the rotor so as to provide an equal number of radial slots. An external stator portion of the device preferably comprises a partially toroidal chamber having an axis coincident with the rotational axis of the device. In a preferred embodiment of the external stator, the toroidal chamber is split along a plane perpendicular to the axis at a point corresponding to the center of the rotor, thus forming two mating halves. Each half comprises a cam groove along an edge of the respective mating face. When the external stator is assembled, the two grooves mate together to form a single cam track having a contour similar in shape to the inner peripheral toroidal wall contour. Moreover, as is shown in FIGS. 4 and 5, the preferred cam track has a re-entrant, or undercut, shape when viewed in a radial section perpendicular to the track so that the track can capture a cam follower. Sliding and rolling cam follower elements, such as ball elements, can engage this track and be captured therein. Each preferred vane comprises an outer tip ring portion for enclosing a respective ball element that is entrapped within the cam track so as to serve as a cam follower. The tip ring portion is fixedly connected to the main body of the preferred vane by an elongated portion having a diameter selected to fit through a narrow neck portion of the reentrant cam track. Because the preferred cam follower and track arrangement provides for capturing the follower within the track, this arrangement allows each associated vane to be both pulled away from the axis of rotation and pushed towards the axis of rotation, thus causing reciprocating sliding movement of the vanes in their respective slots as the rotor rotates. 
     Furthermore, preferred devices comprise an internal stator fixedly secured to the external stator and rotatably enclosed, with clearance, within the central bored portion of the rotor. The internal stator comprises channels connected to ports communicating with inner opening of the rotor compartments. As the rotor spins, a cavity formed between two adjacent vanes defining a radial compartment intermittently communicates with the ports in the internal stator so as to perform intake, compression, power and exhaust functions. Other embodiments may comprise ports and passages in both the internal and the external stator portions. In addition to embodiments serving as two-cycle or four-cycle internal combustion engines, the rotary device of the invention can function as motor-driven or fluid-driven pump or compressor by replacing the internal stator with one having an appropriate port and channel configuration. 
     One object of some embodiments of the invention is to provide a radial sliding vane power device having a simple, efficient and less costly means of vane actuation. 
     A further object of some embodiments of the invention is to provide an improved radial vane rotary power device that is light in weight, small in size and that has the minimum number of parts. 
     Another object of some embodiments of the invention is to provide a rotary power device that can be easily converted to other type of rotary power device such as four-cycle or two-cycle internal combustion engine, pump, compressor, expander, fluid-driven motor and fluid-driven pump devices by a simple modification or replacement of a central stationary member. 
     Another object of some embodiments of the invention is to provide a rotary power device that closely approximates continuous intake, compression, combustion and discharge processes. 
     Yet another object of some embodiments of the invention is to provide a dynamically balanced radial vane rotary power device characterized by reduced noise and vibration. 
     An additional object of some embodiments of the invention is to provide a rotary power device with reduced friction, fluid slip and leakage. 
     These and other objects and advantages of the present invention will be apparent from the following detailed description and the appended claims. 
     Although it is believed that the foregoing recital of features and advantages may be of use to one who is skilled in the art and wishes to learn how to practice the invention, it will be recognized that the foregoing is not intended to list all of the features and advantages. Moreover, it may be noted that various embodiments of the invention may provide various combinations of the hereinbefore cited features and advantages of the invention, and that less than all of the recited features and advantages of the invention may be provided by some embodiments. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an exploded isometric view of a rotary power device of the invention with a portion of a housing cut away for purposes of illustration. 
     FIG. 2 is an isometric view of a rotor having a portion cut away for purposes of illustration. 
     FIG. 3 is an end view of the rotary power device of FIG.  1 . 
     FIG. 4 is a cross-sectional view taken along  4 — 4  of FIG.  3 . 
     FIG. 5 is a detailed cross-sectional view of a portion of the apparatus that is encircled in FIG.  4 . 
     FIG. 6 is an isometric view of a rotary power device of FIG. 1 configured for operation as four-cycle internal combustion engine. A portion of the external stator has been cut away for purposes of illustration. 
     FIG. 6 a  is an isometric view of another rotary power device of the invention arranged to operate as four-cycle internal combustion engine. A portion of the external stator is cut away for purposes of illustration. 
     FIG. 6 b  is an isometric view of yet another rotary power device of the invention arranged to operate as a motor-driven pump or compressor. A portion of the external stator in this figure is cut away for purposes of illustration. 
     FIG. 6 c  is an isometric view of still another rotary power device of the invention arranged to operate as a fluid-driven pump or compressor. A portion of the external stator in this figure has been cut away for purposes of illustration. 
     FIG. 6 d  is an isometric view of a yet another rotary power device of the invention that is arranged to operate as a two-cycle internal combustion engine. A portion of the external stator is cut away in this figure for purposes of illustration. 
     FIG. 7 is a side elevation view of the rotary power device of FIG.  6 . 
     FIG. 7 a  is a side elevation view of the rotary power device of FIG. 6 a.    
     FIG. 7 b  is a side elevation view of the rotary power device of FIG. 6 b.    
     FIG. 7 c  is a side elevation view of the rotary power device of FIG. 6 c.    
     FIG. 7 d  is a side elevation view of the rotary power device of FIG. 6 d.    
     FIG. 8 is a sectional view taken along line  8 — 8  of FIG.  7 . 
     FIG. 8 a  is a sectional view taken along line  8   a — 8   a  of FIG. 7 a.    
     FIG. 8 b  is a sectional view taken along line  8   b — 8   b  of FIG. 7 b.    
     FIG. 8 c  is a sectional view taken along line  8   c — 8   c  of FIG. 7 c.    
     FIG. 8 d  is a sectional view taken along line  8   d — 8   d  of FIG. 7 d.    
     FIG. 9 is an end view of the rotary power device of FIG. 6 d.    
     FIG. 10 is a sectional view taken along line  10 — 10  of FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring initially to FIG. 1, one finds a rotary power device  10  operable as a four-cycle internal combustion engine. This device comprises an external stator portion  14  comprising an elliptical chamber having a peripheral wall  15  that, when viewed in a plane including the axis of rotation  22 , has a semi-circular shape. The peripheral wall comprises a medially surrounding cam track  32 . The preferred chamber is depicted split along a medial transverse plane perpendicular to the axis of the device, thereby forming two mating stator portions: a front stator portion  14   a  and a back stator portion  14   b . Each stator portion  14   a ,  14   b  comprises a respective peripheral wall portion  15   a  and  15   b . The two stator portions preferably comprise respective mirror-image cam groove portions  32   a ,  32   b  open to the medial transverse plane and proximal to the outer peripheral surface of the chamber so as to provide a preferred reentrant cam track  32  when the two portions  14   a ,  14   b  of the stator are clamped together. Thus, the preferred cam track  32  has mirror symmetry about the medial transverse plane, which is perpendicular to the axis of rotation. This cam track comprises a relatively narrow neck-like passageway extending from the rotor chamber to an enlarged region in which a cam follower may be captured. 
     The front external stator portion  14   a  comprises a central opening  66   a  for rotatably carrying the protruding rotor shaft  18 , and the back external stator portion  14   b  comprises another central opening  66   b  for fixedly mounting a centrally protruding internal stator portion  40 . The two mating external stator portions are fixed together by fixture means such as tie rods (not shown) extending through a set of aligned holes  72 . The back external portion may comprise a side ignition port  64  for mounting an ignition means  24  such as a spark or glow plug. 
     The internal stator portion  40  may be fixedly attached to the back external stator portion through a flange portion  54  by fixture means (not shown). This internal stator portion preferably comprises a cylindrical inwardly projecting portion  52  which comprises a pair of peripheral ports comprising an intake port  56  and exhaust port  58 . These ports may be formed as respective cutouts on the peripheral wall of the stator, where each port may be defined within an approximate 90-degree angular extension. Each of the ports  56 ,  58  is preferably connected to a respective intake  62  or exhaust  60  channel. 
     A preferred rotor assembly  20  is concentrically mounted within the substantially annular chamber defined by the inner walls of the external stator portions and a peripheral wall of the internal stator portion. A preferred rotor assembly comprises, as depicted in FIG. 2, a cylindrical block  36  comprising a front hub portion  19 , a back hub portion  45  and a central end shaft  18 . The cylindrical block may comprise a peripheral wall portion  35  having a semi-circular cross-section. The cylindrical block may further comprise a multiplicity of open-ended radial compartments  44  communicating with a central bore portion  42  by means of respective inner opening  46 . There is also an equal multiplicity of radial slots  38  disposed in alternating relationship with the radial compartments, so that each radial slot is closed at the sides and communicates with the central bore by means of openings  47 . The rotor assembly is preferably rotatably mounted within the external stator by means of a front ball bearing  12   a  and a back ball bearing  12   b . A floating internal bearing  70  may be mounted between a stepped portion of the central bore and a recessed end portion  50  of the central internal stator, as shown in FIG.  4 . The advantage of using an internal bearing  70  is to maintain a close-tolerance fixed clearance between the peripheral wall of the internal stator and the inner wall of the central bore under varying load conditions. 
     A multiplicity of vane assemblies  30  is preferably disposed in the rotor chamber, and arranged so that each vane assembly comprises a vane plate portion  34  having three straight sides and one outer semi-circular side, a ring portion  48  fixed to the outer middle tip of the semi-circular vane portion by means of an extended stub portion  49  that extends radially outward from the vane plate portion, and a ball cam follower element  28  freely enclosed by the ring portion  48 . During assembly, vane elements with respective ball elements are momentarily disposed in one cam groove portion, such as the front cam portion  32   a  of the front external stator portion  14   a , and then closed in by mating the second external stator portion  14   b  with its respective cam groove portion  32   b . As the rotor spins, the vanes reciprocate outwardly and inwardly along respective radii, where the motion of the vanes is controlled and guided by the annular cam  32  engaging the ball elements  28  entrapped within the vane ring portions  48 . As the rotor spins, the ball elements  28 , as shown in FIG. 5, may make contact with the outer circular wall portions or the inner circular wall portions of the cam track while the semi-circular vane tip forms a small clearance with the inner semi-circular peripheral wall, thereby reducing vane tip loading. The ball elements may be made from a self-lubricating material to eliminate the need for oil lubrication. Alternatively, oil lubrication may be provided by injecting oil mixed with an intake charge or by direct injection of oil into the cam groove through an external channel (not shown). The vane may comprise a channel  37 , as shown in FIG.  4  and FIG. 5, connecting the base of the vane to an inner wall portion of the ring  48  as a means of enhancing ball-fluid lubrication. Furthermore, the exemplar engine may be cooled by provision of water jacket cooling passages within the external stator (not shown). 
     An embodiment of the rotary power device  10  functioning as a four-cycle internal combustion engine, as shown in FIG. 6, comprises respective intake and exhaust passageways  60 ,  62  provided in the central internal stator and connected to respective peripheral intake  56 , and exhaust  58  ports, where the ports may be axially aligned with inner openings  46  of the rotor radial compartments  44 . In addition, an ignition means  24  may be provided through an ignition port  64  in the side wall of the external stator portion so that the ignition means can communicate sequentially with each of the chambers as the rotor assembly rotates. 
     An alternative embodiment of a four-cycle rotary power device if the invention  10   a  is shown in FIG. 6 a . In this embodiment the internal stator portion comprises an intake passageway  62  leading to a peripheral intake port  56  axially aligned with inner openings  46  of the rotor radial compartments  44 ; and the external stator portion comprises the exhaust passageway  63  and the ignition means  24 . Here, the exhaust passageway  63  comprises a recessed wall portion in the inner wall of the external stator that is defined over a ninety degree angular displacement and is connected to an exhaust port  67 . 
     Another embodiment  10   b  is operable as one of a motor-driven pump/compressor device or a fluid-driven motor, as shown in FIG. 6 b . Here, the internal stator portion comprises an intake passageway  62  leading to diametrically opposed intake ports  56   a  and  56   b ; and the external stator portion comprises a pair of diametrically opposed exhaust passageways  63   a ,  63   b  formed within the internal wall of the external chamber and connected to respective discharge ports  67   a ,  67   b.    
     Yet another embodiment  10   c  is operable as one of a fluid-driven pump/ compressor device, as shown in FIG. 6 c . In this embodiment the internal stator portion comprises two separate intake passageways  62   a ,  62   b  leading to respective diametrically opposed intake ports  56   a ,  56   b . Each of these passageways is in communication with a differently pressurized fluid source. The external stator portion comprises a pair of diametrically opposed exhaust passageways  63   a ,  63   b  formed as recessed wall portion within the internal wall of the chamber and connected to respective discharge ports  67   a ,  67   b  respectively associated with the two fluids. 
     An embodiment  10   d  operable as a two-cycle internal combustion engine is shown in FIG. 6 d . Here, the internal stator portion comprises an intake passageway  62  leading to diametrically opposed intake ports; and the external stator portion comprises a pair of diametrically opposed exhaust passageways  63   a ,  63   b  formed as recessed wall portions within the internal wall of the external stator and connected to respective discharge ports  67   a ,  67   b . A pair of diametrically opposed ignition ports  65   a ,  65   b  formed in the side wall of the external stator may be provided to receive respective ignition means, such as a fuel injecting means. 
     In operation as a four-cycle internal combustion engine, FIG.  7  and FIG. 8 presents views of the engine corresponding to the embodiment shown in FIG.  1  and FIG.  6 . In this embodiment a starter motor (not shown) is connected to the shaft  18  to initiate the rotation of the rotor  20  to start the engine. Each cavity is bounded by two adjacent extended vanes and encloses a radial compartment  44  that moves through four phases comprising intake, compression, power and exhaust phases at the completion of revolution, each phase taking place within a 90° angular displacement of the rotor. Step by step operation of the four phase internal combustion is explained with reference to FIG.  8 . For example, consider a clockwise rotation of the rotor and the movement of a cavity bounded by two adjacent vanes starting at the bottom-most position where the cavity volume is minimum, which corresponds to top dead center (TDC) in a conventional reciprocating engine. As the rotor turns, the volume increases gradually and the inlet port  56  in communication with channel  62  of the central internal stator registers with rotor compartment inner openings  46  so as to perform intake of a fuel/air mixture. This phase terminates at the end of a ninety degree angular displacement, at which point the cavity volume attains a maximum value corresponding to the first bottom dead center (BDC) position in a conventional engine. During the second phase, the cavity volume decreases as the inner opening  46  is blocked by the peripheral wall portion of the internal stator, thus compressing the charge. The second phase terminates at a second minimum cavity volume corresponding to the second (TDC) in a conventional engine. During the third phase, the compressed charge is ignited as the cavity registers with the ignition means  24 ; and subsequently, a power phase is initiated in which the cavity volume increases while the compartment inner openings  46  are blocked again by the cylindrical wall portion  52 . The effect of the resultant pressure forces of the expanding gases on the extended vanes provides a larger tangential force on that vane having the larger extended area, which provides the propelling torque causing the rotation of the rotor. The expansion process continues for a ninety degree angular displacement until the cavity volume reaches a second maximum corresponding to the second (BDC) position in a conventional engine. At the beginning of the fourth phase, a brief blow-down of combustion products takes place followed by an exhaust process as the volume decreases while the inner opening  46  registers with the exhaust port  58  in communication with an exhaust channel  60 . 
     An alternative embodiment of a four-cycle internal combustion engine is shown in FIG. 7 a  and FIG. 8 a , which corresponds to the engine of FIG. 6 a . The operation of the alternative four-cycle is similar to the original embodiment except for the disposition of the exhaust process. In this embodiment the exhaust process is performed through a passage  63  comprising a recessed wall portion in the inner wall of the external stator in communication with an exhaust port  67 . Here, the cavity registers with the exhaust channel  63  while the cavity volume is decreasing, thereby expelling the combustion products through the exhaust passageway  63  connected to the exhaust port  67 . One main advantage of this embodiment is to reduce the chance of short-circuiting in which a portion of the combustion products combine with the intake charge. 
     The rotary power device  10  can be easily converted to serve a different purpose other than the four-cycle internal combustion engine. This is accomplished by a simple replacement of the internal stator portion  40  and a corresponding change in the disposition of ports in the external stator, as shown in FIG. 7 b  and FIG.8 b , corresponding the device  10   b  shown in FIG. 6 b . One such embodiment is a device that can function as one of double-action pump/compressor or a fluid-driven motor In this configuration, the central stator comprises a single intake channel  62  connected to two diagonally opposed peripheral intake ports  56   a ,  56   b ; and the inner wall of the external stator comprises two diagonally disposed passageways  63   a ,  63   b  formed as recessed inner wall portions of the external stator and connected to respective discharge ports  67   a ,  67   b . Each of these passageways extends over a ninety degree angular displacement and is disposed in alternating relationship with respect to the intake ports. 
     In functioning as a pump or compressor, the rotor is made to rotate by coupling the end shaft  18  to a driving means such as a motor. A sealed cavity is enclosed between two vanes having outer vane tips making small clearance engagement with the toroidal wall and side wall of the chamber. Each cavity is preferably bounded by two vanes and encloses a radial compartment that goes through two ninety degree angular displacements of expanding volume alternated by two ninety degree angular displacements of contracting volume. During the expanding volume ranges, fluid is sucked in as the inner opening  46  registers with intake ports  56   a ,  56   b . During the contracting volume ranges the fluid is pressurized and expelled as the inner opening  46  registers with discharge passageways  63   a ,  63   b  connected to respective discharge ports  67   a ,  67   b . Thus, simultaneous processes of diagonal intake and diagonal exhaust take place as the rotor rotates. 
     In functioning as a fluid driven motor or expander device, a pressurized fluid communicated through the intake channels  62  in communication with the ports  56   a ,  56   b  provides a net turning force on the differential extended vane area as the cavities expand, thus causing rotation of the rotor. At the same time, the resulting rotation causes the expulsion of the depressurized fluid through discharge passageways  63   a ,  63   b  that are connected to respective discharge ports  67   a ,  67   b  when the cavities contract in volume. 
     Still another embodiment is a rotary power device operating as a fluid-driven pump or as an energy recovery device as shown in FIG. 7 c  and FIG. 8 c , which correspond to a device  10   c  shown in FIG. 6 c . Exemplar applications include operation as a fluid-driven pump or compressor, as a turbocharger for internal combustion engines and as an energy recovery device useful in reverse osmosis plants. In this embodiment the internal central stator portion comprises two separate intake channels  62   a ,  62   b , each connected to a respective diagonally opposed port  56   a ,  56   b  corresponding to the two differently pressurized fluids. The inner wall of the external stator comprises two diametrically disposed discharge passageways  63   a ,  63   b  formed as a recessed inner wall portion and connected to respective discharge ports  67   a ,  67   b  associated with the two fluids. In operation as a fluid driven pump or energy recovery device, a fluid I of higher pressure is communicated to one intake channel, for example  62   a , and a second fluid II of lower pressure is communicated to a second intake channel  62   b . The higher pressure fluid I fills one quadrant of expanding cavities during the intake phase and discharges fluid through the subsequent quadrant of contracting cavities registering with discharge passageway  63   a  connected to the discharge port  67   a  during the discharge phase. Similarly, the lower pressure fluid II fills a diagonally opposing quadrant of expanding cavities during the intake phase and discharges fluid through the subsequent quadrant of contracting cavities registering with discharge passageway  63   b  connected to discharge port  67   b  during the discharge phase. The effect of net pressure forces on vanes caused by the high-pressure fluid during the intake phase is to impart rotation to the rotor and to pressurize the lower pressure fluid in the diagonally contracting cavities. Thus, a pressure energy exchange takes place whereby a significant portion of the higher-pressure fluid I energy is converted to hydraulic pressure energy transmitted to the lower-pressure energy fluid II, with the remaining portion of energy comprising friction losses and mechanical energy of the rotating rotor. 
     In still another embodiment, the rotary power device  10  can be configured as a two-cycle internal combustion engine as depicted in FIG. 7 d , FIG. 8 d , FIG.  9  and FIG. 10, corresponding to the device shown in FIG.6 d . In this embodiment, the internal stator comprises an intake passageway  62  connected to diagonal opposed intake ports  56   a ,  56   b , and the external stator comprises diagonally opposed exhaust passageways  63   a ,  63   b  connected to respect exhaust ports  67   a ,  67   b . Each exhaust passageway is formed as a recessed wall portion in the inner wall of the external stator extending over an angular displacement enclosing the respect angular displacement of the intake port. A pair of diagonally disposed ignition ports  65   a ,  65   b  comprising ignition means is included in the external stator portion. 
     The operation of the two-cycle engine may be explained with reference to FIG. 8 d . In this embodiment the rotor goes through three distinct doubly repeating phases comprising compression, power, and exhaust-scavenging phases. Each set of three phases takes place within one hundred eighty degrees of rotor revolution and each phase takes place simultaneously with a similar diagonally opposed phase of the other set. During the exhaust-scavenging phase in which the intake ports  56   a ,  56   b  overlap with portions of the respective exhaust passageways  63   a ,  63   b  the intake charge displaces the products of combustion which are expelled through ports  67   a  and  67   b , respectively. During the compression phase the entrapped charge is compressed as cavities contract to their respective minimum values, during which time the compartment inner openings  46  are blocked by the peripheral wall of the internal stator. A double diagonal opposed ignition or fuel injection actuates simultaneously commencing at the beginning of the power phase as sectors of opposing cavities expand. The power phase is followed by an exhaust blow down phase as the cavities start registering with exhaust passageways  63   a ,  63   b  over a small angular displacement followed by a scavenging phase. 
     As will be understood by those skilled in the art, various embodiments other than those described in detail in the specification are possible without departing from the scope of the invention will occur to those skilled in the art. It is, therefore, to be understood that the invention is to be limited only by the appended claims.