Patent Publication Number: US-6210135-B1

Title: Internal combustion rotary engine

Description:
This application claims benefit of Application Provisional Ser. No. 06/065,752, filed Nov. 20, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to a unconventional displacement engine of the rotary type, and more particularly to a rotary engine having an improved force transfer mechanism, an improved rotor assembly with effective cooling, sealing and lubrications systems, and a multi-functional manifold. 
     In conventional internal combustion engines heat energy is converted to translating or reciprocal mechanical energy of pistons which is then converted to rotational energy that drives a drive shaft. Piston rings are provided as contact surfaces between the piston and cylinder walls. The rings seal the lower portion of a combustion chamber to retain compression, scrape excess oil from the cylinder walls and to transfer heat from the piston to the cylinder walls. Approximately 50% of all mechanical losses are attributed to the piston rings, and about one-half of these are attributed to oil scraping. Mechanical loss due to friction results in less heat being used for power generation. 
     In addition, the structural design of the conventional engine does not facilitate easy modification. For example, it is not possible to change engine displacement by changing sizes of engine components. Generally, a family of engines having different numbers of cylinders and different displacements are provided. 
     A currently commercially available rotary engine, such as the Wankel engine is compact, lightweight, simple in design and capable of producing high power relative to its size with high mechanical loss. However, the Wankel engine is not fuel efficient because of inherent problems due to the shape of the pistons, and poor heat transfer due to inadequate cooling of the rotating members. 
     A variety of rotary piston engines have been proposed recently to improve the Wankel engine by altering the piston shape and the mechanism that ensures proper movement of the pistons. One such engine is disclosed in U.S. Pat. No. 5,133,317 to Sakita which discloses a rotary engine having an eccentric elliptical gear assembly interconnected with the rotating piston assemblies. However, with this configuration, the teeth of the gear assembly may experience most of the internal forces generated during combustion and may fail. Further, the gear assembly is generally not compact, has many moving parts which contribute to mechanical loss, and may be expensive to manufacture and maintain. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a new internal combustion rotary engine having a centrally located manifold, an improved force transfer mechanism which reduces internal forces, an efficient cooling system, and a lubrication system which not only lubricates moving parts, but also seals piston contact surfaces. 
     In accordance with the principles of the invention, this object is attained by providing an internal combustion rotary engine including a stationary, centrally located manifold having an intake and an exhaust port. Inner and outer rotor assemblies are provided which rotate in a common direction about the centrally located manifold. Each of the inner and outer rotor assemblies includes two pairs of diametrically opposed pistons, generally of octagonal shape which divide a rotating internal volume, defined by the outer rotor assembly, into four working chambers. Pistons of the inner rotor assembly slide along related walls of the outer rotor assembly and by this arrangement, the four working chambers communicate periodically with the intake and exhaust ports. Angular movement of the inner rotor assembly against the outer rotor assembly ensures that each working chamber is at minimum volume and at a maximum volume four times per revolution of a crankshaft of the engine. When diametrically opposed working chambers are at their maximum volume, the two other diametrically opposed working chambers are at their minimum volume. 
     The working stroke of the engine is defined as a maximum angle between two adjacent pistons. This maximum angle defines an arc length which is equivalent to the stroke of a conventional engine. 
     Movement of the rotor assemblies and transfer of forces generated during operation of the engine is accommodated by a force transmitting mechanism. The mechanism includes a crankshaft, a main crank member, connecting links, and timing gear structure. The timing gear structure controls the rotation of the main crank member around crankshaft at an angle equal to the angle of rotation of the crankshaft. Rotation of the crankshaft may occur in the same direction as rotation of the rotor assemblies, or may occur in the opposite direction, depending on the particular arrangement of the engine. 
     The engine has an efficient cooling system which provides cooling of all rotating and stationary parts that are heated or contacted by the combustion process. An important feature of the invention is the provision of an internally located water pump or impeller driven by the crankshaft. Depending on the arrangement of the engine, the impeller may rotate in a direction opposite to a direction of rotation of the rotor assemblies, or may rotate in the same direction as the rotor assemblies. The pistons are liquid-cooled along with housings of the inner an outer rotor assemblies via water drawn into the engine by the impeller. 
     The engine also has a lubricating system which not only provides lubrication for moving parts, e.g., bearings, etc., but in addition, provides oil flow along piston sealing lines. Oil flows along chevrons defined in the pistons to seal piston contact surfaces. Oil is returned to an oil reservoir via passages in the outer rotor assembly. The shape of pistons of the inner rotor assembly is defined for proper oil drainage. 
     Another object of the present invention is the provision of a device of the type described which is simple in construction, effective in operation and economical to manufacture and maintain. 
     These and other objects of the present invention will become apparent during the course of the following detailed description and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIGS. 1A and 1B are a schematic illustrations of an internal combustion rotary engine provided in accordance with the principles of a first embodiment of the present invention; 
     FIG. 2 is an front view of the main portion of crankshaft structure of the engine; 
     FIG. 3 is a rear view of the main portion of the crankshaft structure; 
     FIG. 4 is a front view of a crank member of the main crank assembly; 
     FIG. 5 is a front view of a crank arm portion of the crankshaft structure; 
     FIG. 6 is a perspective view of the first rotor assembly of the engine; 
     FIG. 7 is an end view of a connection disk of the first rotor assembly; 
     FIG. 8 is a partial perspective view of the second rotor assembly of the engine; 
     FIG. 9 is a front view of a connection member of the second rotor assembly; 
     FIG. 10 is a rear view of a distribution disk of the first rotor assembly; 
     FIG. 11A is a sectional view of a piston of the first rotor assembly; 
     FIG. 11B is a front view of a piston of the first rotor assembly; 
     FIG. 12 is a perspective view, partially in section, of a piston of the first rotor assembly; 
     FIGS. 13A-13J are schematic illustrations of the mechanism of the invention shown at various positions of revolution; 
     FIG. 13K is a schematic illustration of the mechanism of the invention showing equal forces at links L which results in the absence of torque during combustion; 
     FIG. 14 is a perspective view, partially in section, of a body of the first rotor assembly; 
     FIG. 15 is a front view of a piston of the second rotor assembly; 
     FIG. 16 is a view of pistons of the second rotor assembly, shown partially in section to indicate oil flow paths; 
     FIG. 16 a  is a sectional view taken along the line  16   a — 16   a  of FIG.  16 . 
     FIG. 17 is a perspective view of the manifold of the engine of the invention showing the intake and exhaust ports; 
     FIG. 18 is a perspective view of the manifold of the engine of the invention showing injector location; 
     FIG. 19 is a sectional view the manifold of the invention showing the intake and exhaust ports and the location of an injector or a spark plug; 
     FIG. 20 is a chart that schematically illustrates a portion of the sequence of operation of the engine; 
     FIG. 21 is a chart illustrating piston locations during an operating sequence; 
     FIG. 22 is an exploded perspective view of the liquid cooling distribution structure of the engine; 
     FIG. 23 is a perspective view of a force transfer mechanism provided in accordance with the principles of a second embodiment of the present invention; 
     FIG. 24 is an illustration of the stroke of the engine of the invention; 
     FIG. 25 is a schematic illustration of the mechanism of the invention showing the relationship between elements thereof; 
     FIG. 26 is an illustration of a piston of the invention used to determine displacement of the engine; 
     FIG. 27 is a view of a pair of pistons of the invention showing a design angle and an angle of an opening defined in a top portion of one of the pistons of the pair; 
     FIG. 28 is a schematic illustration of an the engine provided in accordance with an second embodiment of the invention; 
     FIG. 29 is a sectional view taken along the line  29 — 29  in FIG. 28; and 
     FIG. 30 is a sectional view taken along the line  30 — 30  in FIG.  28 ; 
    
    
     DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EXEMPLARY EMBODIMENT 
     With reference to FIGS. 1A and 1B, which are identical, a first embodiment of an internal combustion rotary engine is shown, generally indicated at  10 , which embodies the principles of the present invention. FIG. 1A will be used to describe a force transfer mechanism, while FIG. 1B will be used to describe rotor assemblies, and oil and water distribution. It is noted that the right hand portion of FIGS. 1A and 1B are sectional views of pistons of the engine, the pistons being disposed in different planes. 
     As shown in FIG. 1A, the engine includes a housing  12 . A first rotor assembly, generally indicated at  14 , and a second rotor assembly, generally indicated at  16 , are mounted for rotational movement within the housing  12 . The engine also includes a force transfer mechanism, generally indicated at  18 , for controlling the relative movement of the rotor assemblies. 
     With reference to FIG. 1A, the components of the mechanism  18  include crankshaft structure, generally indicated at  20 , that is rotatably supported by bearing structure  22  fixed to the housing  12 . The crankshaft structure  20  is supported so as to rotate about a longitudinal axis  23  thereof and comprises a main portion  21  and a crank arm portion  25  coupled thereto via bolting  27 . As shown in FIG. 2, the main portion  21  includes a connecting boss  29  and an opening  31  for receiving satellite gears, as will be explained below. A stationary gear  24  is fixed with respect to the housing  12  and is axially aligned with the longitudinal axis  23  of the crankshaft structure  20 . A first satellite gear  26  is rotatably coupled to an extending portion of the crankshaft structure  20  at opening  31  for movement about an axis  30  of the satellite gear  26 . The first satellite gear axis  30  is spaced from the longitudinal axis  23  and the first satellite gear  26  includes gear teeth  32  that are in meshing relation with teeth  34  of the stationary gear  24  so that the satellite gear  26  moves about the longitudinal axis  23  of the crankshaft structure  20 . A second satellite gear  36  is coupled to the first satellite gear  26  by bolting  38  so as to be coaxial with the first satellite gear  26  to rotate in the same direction as the first satellite gear, and to move with the first satellite gear about the longitudinal axis  23 . 
     A main crank assembly  40  is supported via bearings  42  for rotation about shaft portion  44  of the crankshaft structure  20 . The main crank assembly is mounted for rotational movement about an axis  46  of the shaft portion  44 . As shown in FIG. 1A, the main crank assembly  40  includes a main gear  48  that is in meshing relation with teeth of the second satellite gear  36 . The main crank assembly  40  also includes a crank member  50  operatively coupled with the main gear  48  and having diametrically opposed connection locations in the form of through holes  52  and  54 . As best shown in FIG. 4, centers of the connection locations  52  and  54  are each located an equal radial distance R from the central rotational axis  46  thereof. The crank member  50  is supported by a bearings  42 , as shown in FIG.  1 A. The gears of the mechanism  18  are designed such that: 
     
       
         ( n   3    n   5′ )/( n   4    n   5 )=2,  
       
     
     where n 3  is the number of gear teeth on the stationary gear  24 , 
     n 5′  is the number of teeth on second satellite gear  36 , 
     n 4  is the number of teeth on the main gear  48 , and 
     n 5  is the number of teeth on the first satellite gear  26 . 
     Although, in the illustrated embodiment, intermeshing gears are provided, it can be appreciated that other means of causing movement of the main crank assembly  40  could be provided. For example, instead of intermeshing gears, fluid couplings, sprockets and chains could be employed to facilitate the same movements. 
     As shown in FIG. 1A, first and second connecting links  58  and  60  are provided, with one end of each link being rotatably coupled to an associated connection location  52  and  54  of the crank member  50  via a pin connection  62 . The links  58  and  60  are of equal length. Although only link  58  is shown connected to the crank member  50  in FIG. 1A due to the location where the cross-section was taken, it can be appreciated that link  60  is coupled to the crank member  50  is a manner identical to that of link  58 . 
     As shown in FIG. 1A, the crank arm portion  25  of the crankshaft structure  20  is coupled to the main portion  21  of the crankshaft structure  20  by bolting and a keyed connection, generally indicated at  67 . With reference to FIGS. 3 and 5, the keyed connection is formed by providing a slot  68  in arm portion  25  and a recess  69  in main portion  21  which receive key  71  such that arm portion  25  is locked to and rotates with main portion  21 . As shown in FIG. 1A, the crank arm portion  25  is supported for rotation by bearing  70  and has a first rotational axis  72  that is aligned with the main crank assembly axis  46  and a second rotational axis  74  that is spaced from the first axis  72  and aligned with the longitudinal axis  23  of the crankshaft structure  20 . The crank arm portion  25  is operatively associated with the main crank assembly  40  via shaft portion  44  so as to rotate about the main crank assembly axis  46 . 
     As shown in FIG. 1B, the first rotor assembly  14  is coupled to the crank arm portion  25  via bearing  70  so as to rotate about axis  74 . As best shown in FIGS. 1B and  6 , the first rotor assembly  14  comprises a rotatable body  80  defining connecting portion  76  and a cylindrical water distribution disk member  82  bolted to the body  80  on a face thereof opposite to the face where the connecting portion  76  is located. A center of the connecting portion  76  is located at a predetermined radial distance B (FIG. 7) from the longitudinal axis  23 , which is common with axis  74 . A second end of link  58  is rotatably coupled via a pin  78  to the connecting portion  76  of the first rotor assembly  14 . A piston assembly including a pair of diametrically opposed, identically configured pistons  84 A 1  and  84 A 2  is coupled to the disk member  82  via bolts  86 . 
     As shown in FIG. 1B, the second rotor assembly  16  is oriented concentrically with the first rotor assembly  14  and is mounted for rotation about the axis  74  and thus the longitudinal axis  23 . As best shown in FIGS. 1A and 8, the second rotor assembly  16  has a main body  88  in the form of a generally cylindrical drum defining an internal volume  104 , which is a rotating displacement volume. The body  88  has a drum  87  (FIG. 9) coupled to end  89  thereof to defining a connecting portion  90 . As seen in FIG. 9, a center of the connecting portion  90  is located a radial distance C from the second axis  74  and thus the longitudinal axis  23  that is equal to the radial distance B defined between the connecting portion  76  of the first rotating assembly and axis  74 . A second end of the link  60  is rotatably coupled via a pin  79  to the connecting portion  90  of the second rotor assembly  16 . In the illustrated embodiment, the first rotor assembly  14  is disposed within the internal volume  104  of drum body  88  and is mounted for rotation therein via bearings  92  and  94  (FIG  1 B). The second rotor assembly  16  is mounted for rotation with respect to the housing  12  via bearings  96  and  98 . In the embodiment, all bearings are conventional ball bearings that are selected for specific loads and size of the engine. It can be appreciated that any known type of bearings could be employed. 
     The second rotor assembly  16  includes a second piston assembly having a pair of diametrically opposed, pistons  100 B 1  and  100 B 2  coupled to an interior portion  101  of the drum body  88  via a plurality of bolts  102 . 
     As best shown schematically in FIG. 20, pistons  100 B 1,    100 B 2  divide the internal volume  104  into two sections, and the two sections are in turn each divided into two working chambers by pistons  84 A 1 ,  84 A 2 . Thus, pistons  84 A 1 ,  84 A 2  and  100 B 1,    100 B 2  are oriented within the rotating internal volume  104  so as to divide the rotating internal volume  104  into two pairs of diametrically opposite working chambers A and C, B and D. As will become apparent below, the pistons assemblies operate at periodically variable speeds such that periodically variable volume working chambers are provided between adjacent pistons. 
     As best shown in FIGS. 6,  10  and  11 A, pistons  84 A 1  and  84 A 2  have a front face  103  including a curved portion  103 ′, an opposing rear face  105  including curved portion  105 ′, opposing sidewalls  107  and  107 ′, top surfaces  109  and  109 ′ and a curved bottom surface  111 , joined to define an interior volume  106 . Surfaces  109 ′ slide on the interior surface of body  88  of the second rotor assembly  16  during operation of the engine  10 . Boss  108  (FIG. 11A) is provided having bolt holes for coupling the pistons to the disk  82  (FIG.  10 ), and a water separator  110  is defined internally (FIG.  12 ). As shown in FIG. 11, opposing sidewalls  107  each include a part-spherical recess  112 , the function of which will become apparent below. The shape of pistons  84 A 1  and  84 A 2  provides the following advantages: port possibilities for spark plugs or injection devices, the angled shapes simplifies manufacturing, and there is minimum surface area to be sealed which reduces friction and heat losses which means that the exhaust port can be opened much later in the cycle. 
     An important feature of pistons  84 A 1  and  84 A 2  is opening or recess  213  (FIG. 6) therein for the collection and disposal of excessive oil through oil drainage holes  215  in body  88 , as will become more apparent below. For this reason, with reference to FIG. 27, the angle ε of the opening  213  is:        ɛ   =     γ   +       (     d   ·   360     )       (     2      π                   R   pr       )                         
     where d is the diameter of the drain holes, R pr  the outer radius of the piston (profile radius). 
     As best shown in FIGS. 15 and 16, pistons  100 B 1  and  100 B 2  have a top surface  113 , a bottom surface  115 , a front surface  117  including curved portion  117 ′ and an opposing rear surface, and opposing sidewalls  119  and  119 ′, joined to define an interior volume  116 . Opposing sidewalls  119  and  119 ′ each include a part-spherical recess  120  which mates with a corresponding recess  112  in the pistons  84 A 1  and  84 A 2  when pistons  84 A and  100 B are adjacent, to form a spherical combustion chamber during rotation of the pistons  84 A and  100 B. In the illustrated embodiment, approximately three-fourths of the volume of the combustion chamber is formed from recess  120 . Each sidewall of the pistons  84 A and  100 B which mate to form a combustion chamber is generally octagonal in shape having eight edges which approaches a circular shape and is simple to manufacture. It is noted that the pistons are designed so as to be thermally compensated. Thus, as the engine heats, the combustion chamber formed by the recesses  120  and  112  in the pistons  100 B and  84 A will take its spherical configuration. The spherical combustion chambers have a small surface area which heats thus, less heat transfer therefrom is required. As discussed above, pistons  100 B and  84 A in FIG. 1B are shown to be in the same plane for illustrative purposes only. It can be appreciated that pistons  100 B and  84 A are in different planes in FIGS. 1A and 1B. 
     With reference to the figures, particularly FIGS. 1A and 13, the operation of the mechanism  18  which ensures movement of the pistons  84 A 1    84 A 2 ,  100 B 1  and  100 B 2 , at periodically variable speeds will be appreciated. FIG. 13 schematically shows the positional relationships during various degrees of rotation of the mechanism  18  between the radius B taken from the longitudinal axis  23  (point P in FIG. 13A) to the connecting portion  58  of rotor assembly  14 , the radius C taken from the longitudinal axis  23  (point P) to the connecting portion  90  of rotor assembly  16 , the radius R of crank member  50  taken from the axis  46  (point T in FIG. 13A) to a connection location  52  of crank member  50 , and the radius F taken from axis  23  to axis  46  (from point P to point T in FIG.  13 A). As shown, when crank arm portion  25  (and crankshaft structure  20 ) moves in one direction about the longitudinal axis  23  (point P), the main crank assembly including crank member  50  moves in the opposite direction about the longitudinal axis  46 . Since the connecting links  58  and  60  couple the crank member  50  to an associated rotor assembly  14  and  16 , the rotor assemblies  14  and  16  move in the same direction relative to each other at periodically various speeds and move about the longitudinal axis  23  in a direction opposite to the direction of rotation of the crank arm portion  25  of the crankshaft structure  20 . 
     It can be appreciated with reference to FIGS. 1B,  13 A- 13 J that the mechanism  18  ensures that for any degree of rotation of the crank arm portion  25  (represented as radius F), there is an equal degree of rotation against the crank arm portion. FIGS. 3A-13J also clearly show that the crank arm portion  25  and the crank member  50  rotate in opposite directions. These relationships hold true throughout a full rotation of the mechanism  18  since the radial lengths B and C between the longitudinal axis of rotation  23  and the connecting portions  76  and  90  are equal, the radial length between the axis of rotation  23  and the connection locations  52  and  54  of the crank member  50  are equal, and since the links  58  and  60  have equal length. It can be appreciated then that since the rotor assemblies  14  and  16  are coupled to associated piston assemblies, the piston assemblies move at periodically variable speeds. This occurs since the axis  46  of the main crank assembly  40  is spaced or offset from the longitudinal axis  23 . Thus, since the crankshaft structure  20  is rotating at a constant speed, as the radial distance between the connection locations  52  and  54  and the longitudinal axis  23  increases, the speed of the rotor assembly (and thus pistons) connected at that location decreases, and as the above-mentioned radial distance decreases, the speed of the rotor assembly (and thus pistons) disposed at the short radial length connection location increases, thereby providing variable speed movement of the rotor assemblies  14  and  16  during one revolution thereof. 
     To understand the “stroke” of the engine  10 , an angle γ is defined as the maximum angle between two adjacent pistons  84 A and  100 B. This angle γ is the working angle and the length of an arc defined by γ is equivalent to the stroke of a conventional engine (FIG.  24 ). In the engine of the embodiment, γ is set at 64 degrees. It can be appreciated that γ is selected for the particular engine design and may be more that 64 degrees. For example, in the second embodiment of the invention (FIG.  28 ), γ is set at 71 degrees. 
     With reference to FIGS. 24 and 26, the displacement of the engine will be appreciated. The displacement at each single chamber of the engine is: 
     
       
         
           V′=C 
           S 
           ·S 
           a  
         
       
     
     where C S  is the cross sectional area of the piston 
     S a  is the working stroke,          S   a     =       2      π                   r   0        γ     360                     
     γ is the stroke angle (angle of the piston rotation between TDC and BDC). 
     The engine displacement is thus V=4V′. It can be appreciated that by manipulating γ, the displacement of the engine can be changed. 
     The piston angle θ (FIGS. 11 and 27) is calculated as follows: 
     θ=(360−(2−γ)−(4·β))/4, where β is a dead angle, the equivalent of the gap between a piston and cylinder head in a conventional engine and chosen for the particular design. Thus, in the illustrated embodiment, θ is the same for pistons  84 A and  100 B and is approximately in the range of 50-60 degrees which controls the timing of the engine. 
     Further, with γ chosen for rotor design and radius C=radius B being known, as shown in FIG. 25, the radius or length F can be determined by: 
     
       
           F=C−C /(1+tan (γ/4)),  
       
     
     where C/(1+tan (γ/4)) is a dimension of the crank member equal to R (see FIG.  4 ). Thus, F=C−R or F=R·tan (γ/4). 
     In addition, the length of each connecting link  58  and  60  is determined by: 
     
       
           L =( C   2 −( F   2   +R   2 )) ½   
       
     
     Another important feature of the mechanism  18  is that during the power stroke, the gears  24 ,  26 ,  36  and  48  are generally not loaded due to the geometry of the mechanism  18 . During combustion (when pressure and forces are at a maximum), the most vulnerable link of the mechanism  18  is the teeth of the timing gears of the mechanism. Thus, to avoid damage to the gear teeth, the mechanism is designed to direct forces from the rotor assemblies  14  and  16  to the crankshaft structure mostly through the connecting links  68  and  60  to the pins  62 ,  78  and  79 , without torque. Each connecting link is loaded approximately ⅔ of the initial gas force. With reference to FIG. 13K, it can be seen that during combustion, F C =F B  with the resulting force R f =(F C +F B ) cos (γ/4). Since F C =F B , there is no torque generated at TDC and BDC, thus the resultant force is on the pins at connecting portions  76  and  90 , and not on the gear teeth. 
     With reference to FIGS. 1B and 22, centrally located within the engine is liquid cooling distribution structure, generally indicated at  119 , comprising an elongated water feed tube  121  in fluid communication with a radiator (not shown) and an impeller  122  adjacent to the feed tube  121  for drawing water from the radiator through the feed tube. The impeller  122  is in threaded engagement with the crank member  50  to rotate about the longitudinal axis  23 . End  127  of the rotating feed tube  121 , which is driven via sprocket  129  may include motion transmitting structure  125  coupled thereto to provide a secondary power source as is known in the art. 
     With reference to FIGS. 1B,  10 , 14 ,  16  and  22 , the water cooling system of the engine  10  will be appreciated. The impeller  122  draws water through the central portion  124  of tube  121 . Water is then directed to passages  126  and  128  in the body  80  and is then directed to the distribution disk  82  to which the pistons  84 A 1  and  84 A 2  are coupled. Water from passage  126  flows into channel  130  (FIG. 10) and enters piston  84 A 2  at inlet  131  while water from passage  128  flows into channel  132  enters piston  84 A 1  at inlet  133 . As shown, the water enters each piston  84 A 1  and  84 A 2  at a bottom portion thereof and flows through a passage  134  in a water separator  110  (FIG. 12) defined in the interior of each piston  84 A 1 ,  84 A 2 . The water circulates in the upper portion of each piston  84 A 1 ,  84 A 2  and exits each piston at respective outlet ports  138  and  140  (FIG. 10) so as to flow into respective channels  142  and  144  located in an outer portion of disk  82 . Water from channels  142  and  144  enters respective passages  146  and  148  (FIG. 14) defined in the body  80 . 
     With reference to FIGS. 1B,  8 , and  22 , water then passes to passage  150  (FIG. 16) located at the outside of tube  121 , and moves through port  152  and into inlet ports  154  in pistons  100 B 1  and  100 B 2  and fills the interior volume of each of these pistons. Water exits piston  100 B 1  and  100 B 2  through their exit ports  156  and flows to main body  88 , which houses pistons  100 B 1  and  100 B 2 . As best shown in FIG. 8, water contacts the outer surface  158  of the main body  88  and then enters a plurality of channels  160  to cool an outer portion of the body  88 . Next, the water in channels  160  communicate with a tube  162  (FIG. 1B) disposed in the interior of each of the pistons  100 B 1  and  100 B 2 . Tube  162  communicates with passage  164  which in turn communicates with passage  165  and is returned to the radiator via water return port  226  of manifold  220 . As seen in FIG. 1B, the liquid cooling distribution structure  119  is sealed by seals  166 , which separates water at the impeller from oil at the crankshaft structure  20 , a pump seal  168  and a seal  170 . 
     Thus, it can be appreciated that the two rotor assemblies  14  and  16  and their corresponding pistons  84 A 1 ,  84 A 2 , and  100 B 1  and  100 B 2,  are cooled effectively by the serial water distribution system of the invention wherein water is first sent through and thereafter is sent through pistons  100 B. It can be appreciated that a parallel cooling circuit could be provided wherein water us sent to pistons  84 A and pistons  100 B in generally simultaneously. 
     With reference to FIG. 1B, it can be seen that oil is used to lubricated and cool rotating engine components. A conventional oil pump  172  draws oil from reservoir  174  and sends oil through passage  176  to lubricate bearing  98 , through passages  178 ,  180 ,  182  and  184  to lubricate the crankshaft structure  20  and bearing structure  22 . Next oil flows through central passage  186  to passage  188  to lubricate bearings  190  of the satellite gears  26  and  36 . Next, oil is sent to bearing  42  and flows through passages  192  in crank member  50  to lubricate the link connections. Oil is pumped through passages  196  and  198  to lubricate bearings  96  and  56 . Oil continues down the central passage  186  to lubricate bearing  70  via passage  200  and bearings  92  and  94  via passages  201 ,  202 , and  203 . 
     Oil is also used to a seal certain piston contact surfaces via chevrons or oil distribution structure defined in the pistons  84 A and  100 B. The chevrons are configured as show in FIG. 11A, having an expander  217  separating two members  221 ′ and  221 ″, thereby defining an oil flow space  219  for delivering oil along contact surfaces. With reference to FIG. 16, after lubricating ring  215  at disk  82 , to seal pistons  100 B contact surfaces oil moves through passages  204  in the body  123  coupled to the second rotor assembly  16 . Passages  204  communicate with chevrons  216  in each of pistons  100 B 1  and  100 B 2  to provide an oil seal between pistons  100 B 1  and  100 B 2  and disk  82 . Oil exits pistons  100 B via port  210 . In addition, oil is sent through passage  205  in body  123  which communicates with chevron  218  in piston  100 B 2  and, via passage  223 , with chevron  218 ′ in piston  100 B 1  to provide an oil seal between the pistons  100 B 1  and  100 B 2  and the manifold  220 . Oil is also directed to seal ring  214  via port  213 . Oil exits through port  221  and returns to the reservoir  174 . Chevrons  216  are generally identically configured as shown in FIG. 16 a , including an expander  217  separated by two members  221 ′ and  221 ″. 
     Sealing of contact surfaces of pistons  84 A 1 ,  84 A 2  will be appreciated with reference to FIG.  1 B. Oil is sent through ports  203  in the disk  82 . Ports  203  communicate with chevrons  207  and  206  in pistons  84 A to provide an oil seal between pistons  84 A and the body  88 . Oil is also directed through passages  211  in disk  82 . Passages  211  communicate with chevrons  209  in pistons  84 A to provide an oil seal between pistons  84 A, body  123  and manifold  220 . As pistons  84 A rotate, oil collects in recess  213  (FIG. 6) in top surface  109  of each the pistons  84 A 1  and  84 A 2  and then is returned to the oil reservoir  174  via diametrically opposed drainage holes  215  in body  88 . Body  88  is thus not sealed. 
     The chevrons  216  and  218  of pistons  100 B 1  and  100 B 2  are best shown in FIG.  8 . Since pistons  84 A 1  and  84 A 2  slide with respect to interior surfaces of main body  88 , pistons  84 A 1  and  84 A 2  have the additional chevrons  206  defined in front surface  103  and the top surfaces  109 ′ thereof (FIG.  6 ), which are employed to provide a seal with the interior surfaces of the main body  88 . 
     As shown in FIG. 1B, the liquid cooling distribution structure  119  is disposed concentrically with an intake an exhaust manifold, generally indicated at  220  that is fixed with respect to the housing  12 . In the broadest aspects of the invention, the liquid cooling distribution structure  119  can be considered to be part of the manifold  220 . A shown in FIGS. 17-19, the intake an exhaust manifold  220  includes an intake port  222  and an exhaust port  224  which communicate with the working chambers upon rotation of the pistons  84 A and  100 B. In addition, a water inlet port  225  is provided for introducing water to the liquid cooling distribution structure. Also, a water return port  226  is provided that communicates with the booster passage  150  to return water to the radiator. With reference to FIGS. 18 and 19, it can be seen that a portion  228  of the manifold  220  opposite the intake and exhaust may house spark plugs and/or fuel injectors  229  disposed around tube  121  of the distribution structure  119 . Point  231  in FIG. 18 represents top dead center (TDC). Thus, with this arrangement, it is relatively easy to replace the spark plugs or injectors  229  by simply removing the liquid cooling distribution structure  119  to gain access to the plugs or injectors. Two or more fuel injectors may be provided to inject fuel on one side of the piston and then on the other side thereof. This gives one injector time to cool down while the other injector is operating. 
     The centrally located manifold  220  provides the intake and exhaust ports at locations where the pistons  84 A and  100 B rotate at relatively low speed, which advantageously reduces mechanical losses. The manifold together with the liquid distribution structure  119  provides effective cooling of the pistons assemblies via water circulating through the pistons which reduces warping of the pistons. Further, the manifold location and design dictates the shape of the pistons  84 A and  100 B, i.e, octagonal. 
     In the illustrated embodiment, the manifold has one intake port and one exhaust port to perform the four stroke cycle. It can be appreciated that two intake ports and two exhaust ports may be provided for a two-cycle engine. 
     In the illustrated embodiment, the engine is designed to operate on diesel fuel. Gasoline or other combustible fuels are also contemplated. In the diesel engine, diesel fuel is injected or sprayed inside a combustion chamber so as to the disposed on a wall thereof and to be in the internal volume thereof, in the known manner. During the compression cycle the fuel is injected by injector  229  before top dead center. If an engine uses spark plugs, the plugs are set to fire a few degrees before top dead center to provide time for combustion. 
     Referring now to FIG. 20, a portion of the sequential operating positions of the engine pistons  84 A 1,    84 A 2 ,  100 B 1  and  100 B 2  are shown schematically and the functions at the four engine working chambers are identified in chart form. The working chambers are defined by the two adjacent pistons between which the working chamber is formed and by the letter A, B, C, and D. Although the pistons of the invention are not identically configured, it is noted that the pistons are shown in FIG. 20 to be of the same wedge shape for ease of illustration. In the illustrated engine operation, air is supplied to the engine through the intake port  222 . Since fuel injection is employed, injection of the fuel can occur either during the compression phase or, at the end of the compression phase. Regardless of how air and fuel are introduced and the working chambers, or how they are ignited, FIG. 20 illustrates engine operation advantages provided by the mechanism employed by the engine of the invention. The piston assemblies are shown at five different positions in FIG. 20, which positions are labeled  1  through  5 . The drawing shows the expansion portion of the cycle. 
     At position  1  of FIG. 20, ignition takes place in working chamber A between pistons  100 B 1  and  84 A 1  when the working chamber A is at substantially its smallest volume, compression starts in working chamber B, air/fuel mixture starts to be drawn into working chamber C through intake port  222  and the exhaust of spent gases through the exhaust port  224  begins at working chamber D. The power, compression, intake and exhaust phases occur at the respective working chambers A, B, C, D and continue from positions  1  through  5  of the piston assemblies shown FIG.  20 . 
     In the piston assembly travel from positions  1  through  5  of FIG. 20, one phase of the four phase operating cycle is completed within each of the working chambers. The entire phase of the four phase operating cycle for one complete revolution of travel can be derived from the discussion above. A complete engine operating cycle takes place at each working chamber with each complete rotation of the piston assemblies, for a total of four complete engine operating cycles per revolution of the piston assemblies. 
     FIG. 21 shows the relationship between the pistons pairs  84 A and pairs  100 B at top dead center at various angles of rotation of the crankshaft structure  20 . 
     With reference to FIG. 28, an internal combustion rotary engine is shown, generally indicated at  300 , which embodies the principles of a second embodiment of the present invention, wherein like parts are given like numerals. It is noted that FIG. 28 is a view similar to that of FIG. 1A, illustrating the interrelation of the elements of the structure. The engine  300  is similar to engine  10 , but has a different force transfer mechanism design and a simpler arrangement. 
     The engine includes a housing  312 . A first rotor assembly, generally indicated at  314 , and a second rotor assembly, generally indicated at  316 , are mounted for rotational movement within the housing  312 . The rotor assemblies  314  and  316  are best shown in FIG.  30  and are configured similarly to those of the first embodiment. The engine  300  also includes a force transfer mechanism, generally indicated at  318 , for controlling the relative movement of the rotor assemblies. 
     The components of the force transfer mechanism  318  are best shown schematically in FIG.  23  and in section in FIG.  30  and include a crankshaft structure  320  is supported by sliding bearings  321  to rotate with respect to housing  312  about longitudinal axis  323 . Crankshaft structure  320  has a shaft  325  having an axis  330  offset from the longitudinal axis  323 . A sungear  335  is fixedly mounted to the housing  312  (not shown in FIG. 23) of the engine  300 . A planetary gear  340  is mounted within the sungear  335  such that external teeth  342  of planetary gear  340  engage with the internal teeth  344  of the sungear  335 . Counterweight  343  is also provided. The relative number of gear teeth is as follows: 
     
       
         (# teeth of sungear 335)/(# teeth of planetary gear 340)=2  
       
     
     A crank member  346  is fixedly coupled to the planetary gear  340  and is mounted for rotation about shaft  325  via sliding bearings  347 . One end of a connecting link  348  is coupled via a pin  350  to one arm of the crank member  346 . The opposite end of link  348  is coupled to the first rotor assembly  314  via pin  352  (FIGS.  28  and  30 ). It is noted that the housing  312  is not shown in FIG. 30 for clarity of illustration. One end of connecting link  354  is coupled via a pin  356  to an opposing arm of the crank member  346 . The opposite end of link  354  is coupled to the second rotor assembly  316  via pin  358  (FIGS.  28  and  30 ). Centers of pins  350  and  356  are spaced an equal distance from axis  330 . The distance between center of pins  356  and  358  is equal to the distance between pins  350  and  352 . 
     Planetary gear  340  is mounted such that rotation of the crank member  346  occurs in a direction opposite to the direction of rotation of the crankshaft structure  320 , as indicated by the arrows in FIG.  23 . It can be appreciated that an idler gear (not shown) may be provided between the planetary gear  340  and the sungear  335  to change the direction of rotation of the crank member  346  if desired. 
     As shown in FIGS. 28, the first rotor assembly  314  is a generally cylindrical rotatable body  380  which defines a connecting portion  376  receiving pin  352 . The cylindrical water distribution disk member  82  is bolted to the body  380  on a face thereof. A piston assembly, generally identical to that of the first embodiment, includes a pair of diametrically opposed, identically configured pistons  84 A 1  and  84 A 2  coupled to the disk member  82  via bolts  86 . 
     The second rotor assembly  316  is oriented concentrically with the first rotor assembly  314  and is mounted for rotation about the axis  323 . The second rotor assembly  316  is generally identical to that of the first embodiment and has a main body  88  in the form of a drum which defines a rotating displacement volume  104 ′. Pistons  100 B 1  and  100 B 2  are mounted to an interior surface of the body  88  (FIG. 29) in the manner described above with reference to the first embodiment of the invention to divide the internal volume  104 ′ into two sections. Pistons  84 A 1  and  84 A 2  divide each of the two sections into two working chambers for a total of four working chambers. The body  88  defines a connecting portion  390  which receives pin  358 . The center  389  of the connecting portion  390  is located a radial distance from the second axis longitudinal axis  323  that is equal to a radial distance from a center  391  of connecting portion  376  to the longitudinal axis  323 , as in the first embodiment. 
     In the illustrated embodiment, the first rotor assembly  314  is disposed within the drum body  88  and is mounted for rotation therein via rolling bearings  392  and  394  (FIG.  28 ). The second rotor assembly  316  is mounted for rotation with respect to the housing  312  via rolling bearings  396  and  398 . 
     As in the first embodiment, fluid distribution structure  119  is provided. However, the water flow paths to cool the pairs of pistons  84 A and  100 B are different from that of the embodiment of FIG.  1 B. In particular, as shown in FIG. 28, water enters inner tube  124  via inlet port  327  and is sent through tube  400  and into the distribution disk  82  and into inlets  131  (FIG. 29) and circulates through pistons  84 A in the manner discussed above with reference to the first embodiment of the invention. Water exits pistons  84 A via tube  410  and moves through passage  420  in body  123  and enters the pistons  100 B and circulates therein, as shown by the arrows in FIG.  28 . Water passes to the outer passage  160  and exits the pistons  100 B through passage  162 . Passage  162  communicates with passage  165  via passage  150  permitting water to exit the manifold  220  and return to the radiator (not shown). 
     The engine  300  also includes oil flow passages for lubricating rotating elements, i.e., bearings, and oil flows along the sealing elements in the manner discussed above with reference to the first embodiment of the invention. For example, oil passages  215  in body  88  (FIG. 29) communicate with pistons  84 A 1,    84 A 2  such that oil may return to the oil reservoir  174 . 
     Port  430  in the manifold  220  is provided for housing the spark plug or injector for the engine  300 . 
     As is evident from the discussion above, movement of the rotor assemblies  314  and  316  is controlled by the mechanism  318  which can be arranged such that the crankshaft structure  320  rotates with an angular velocity of ω crankshaft =(ω rotor 314 +ω rotor 316 )/2(1/sec) in a direction opposite to that of the crank member  346 , where ω rotor 314  is the angular velocity of the rotor assembly  314  and ω rotor 316  is the angular velocity of the rotor assembly  316 . Alternatively, the mechanism  318  can be arranged such that the crankshaft  320  rotates with the angular velocity of ω crankshaft =(ω rotor 314 +ω rotor 316 )/4 (1/sec) in the same direction or rotation as the crank member  346 . 
     It can be appreciated that the mechanism  318  of FIGS. 23 and 28 is arranged in a manner similar to that of FIG. 1A in that reaction forces generated during an operating cycle are equal and in opposite direction at the connections between link  354  and crank member  346  and at the link  348  and the crank member  346 , such that torque is not exerted on the crank member at TDC and BDC. 
     The engine of each embodiment of the invention is fully balanced. Inertia forces occur at the first, second and fourth order harmonics. The inertia forces of the first and second order are balanced simply by counterweights provided in the engine. The inertial forces at the fourth order can be balanced by matching the moments of inertia between the rotor assemblies with that of the crankshaft structure. 
     Another advantage of the invention is the ease in which the engine displacement can changed. Conventionally, a family of engines having different displacements and number of cylinders are provided. With the engine of the invention, it can be  10  appreciated that reducing the size of the rotor assemblies while using the force transfer mechanism sized for the largest engine, the displacement can be changed. In a gas-fueled engine, the size of the rotor assemblies may be increased without changing the mechanism, since in the gasoline engine, less load is required than in diesel engines. Thus, for automotive engines, it is within the contemplation of the invention to provide a series of engine sizes to provide a corresponding series of engine powers, such as 300 hp, 200 hp and 100 hp by simply selecting the types or sizes of rotor assemblies and the force transfer mechanism. 
     A further advantage of the invention is the ability to reduce engine speed by changing the arrangement of the force transfer mechanism. It can be appreciated that the engine of the invention can be used to power helicopters which require high torque. Currently helicopters employ a large and heavy gear box to reduce the speed of the turbine which operates at approximately 12,000 rpm to be approximately 150 rpm at the rotor. With the invention, this reduction in power can be accomplished by changing the gear arrangement of the mechanism, with smaller, more simple gearing. 
     The sealing system of the invention makes it possible to reduce the total sealing surface of the seals to approximately 12-15% from conventional engines, and by eliminating oil scrapers, the total frictional work losses can be reduced to approximately 7-8% of that of conventional engines having oil scrapers. 
     Since the engine of the invention operates twice faster than a conventional engine, and after combustion the speed of the piston increases to exhaust gasses quickly. Thus, by reducing the time of the cycle, heat transfer is reduced which permits more thermal energy to be used for power and not to be rejected to the cooling system. 
     Further, the mechanical losses of the engine of the invention are less than that of a conventional engine since, in the engine of the invention, there is no valve train and there are no friction losses due to the use of piston rings. Thus, with the engine of the invention, less work is spent on friction with more work being used for power. The smaller the friction loss, the longer service life of the engine and the less wear on the principle mating parts. 
     The centrally located manifold provides the intake and exhaust ports at locations where the pistons rotate at relatively low speed, which advantageously reduces mechanical losses. The manifold together with the liquid distribution structure provides effective cooling of the pistons assemblies via water circulating through the pistons which reduces warping of the pistons. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.