Patent Publication Number: US-8109252-B2

Title: Rotary engine combustion chamber

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 60/914,444, filed Apr. 27, 2007. 
    
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable 
     BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention pertains to a rotary engine with multiple planetary rotors orbiting inside the engine housing. More particularly, this invention pertains to facilitating combustion in such a rotary engine. 
     2. Description of the Related Art 
     One type of rotary engine has a main rotor with circular cutouts. Inside each circular cutout is a planetary rotor that orbits the center of rotation of the main rotor. The planetary rotor has faces that sequentially cycle through intake, compression, combustion, and exhaust. Such rotary engines are disclosed in U.S. Pat. Nos. 6,932,047; 7,044,102; 7,350,501; and in patent application Ser. No. 12/041,753, hereby all incorporated by reference. Other rotary engines include those such as the Wankel engine. These engines operate with a different configuration than described herein and experience different problems. In particular, the Wankel-type engines operate with a rotor mounted on an eccentric with the rotor moving within a two-lobed cavity. 
     The compression and combustion cycles occur sequentially as a face of the planetary rotor passes through top dead center (TDC). At TDC, a face of the planetary rotor defines a trailing volume and a leading volume, with the two volumes divided by a bridge protruding from the housing. The trailing volume contains the compressed gas from the compression cycle. The leading volume becomes the combustion chamber as the planetary rotor continues its orbit past TDC. Isolating the trailing and leading volumes when the planetary rotor passes TDC is difficult. 
     In order to ensure complete and efficient combustion, it is known to introduce turbulence in the fuel air mixture in a combustion chamber. The configuration of the rotary engine is such that difficulties are encountered in attempting to maintain isolation when needed and to also introduce turbulence when desired. 
     In the rotary engine, it is desirable to introduce or inject fuel near TDC. At this position, the leading volume is small because of the proximity of the planetary rotor face and the engine housing. It is desirable to keep the leading volume small at the beginning of the combustion cycle and it is desirable to avoid having the injected fuel impinge upon or wet the face of the planetary rotor. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one embodiment of the present invention, a planetary rotor has a multi-faceted face that engages a bridge during the transition from the compression cycle to the combustion cycle with the bridge and face forming a dynamic seal. In this way, the trailing volume is isolated from the leading volume as the face of the planetary rotor passes through top dead center (TDC). 
     In one such embodiment, the planetary rotor face has at least two sections. The first, leading section is an arcuate surface that provides clearance between the rotor face and the trailing edge of the bridge as the planetary rotor orbits in the rotary engine. The second, mid-section is adjacent the bridge with the planetary rotor near TDC and maintains an air gap sufficiently small to form a dynamic seal. 
     According to another embodiment of the present invention, a planetary rotor has a face engaging a bridge during the transition from the compression cycle to the combustion cycle such that the bridge and face have a gap that allows gas flow from the trailing volume to the leading volume and the gap is sufficiently small to quench flame propagation from the leading volume to the trailing volume. In this way, turbulence is introduced into the leading volume of a rotary engine during the period that the fuel is introduced into the leading volume without encouraging flame propagation from the leading volume to the trailing volume. 
     In one such embodiment, the face of the planetary rotor has channels or grooves positioned to increase gas flow during selected portions of the combustion cycle, with the channels or grooves facilitating turbulence in the leading volume by allowing compressed gas from the trailing volume to flow into the leading volume. 
     According to another embodiment of the present invention, the face of the planetary rotor opposite a fuel injector has a pocket. In this way, the fuel cloud is able to expand without impinging or wetting the face of the planetary rotor. In one such embodiment, the pocket has a configuration and shape to accommodate the fanning of the injected fuel as the planetary rotor orbits past the injector. The shape avoids wetting the face of the planetary rotor and the surface of the pocket. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
       The above-mentioned features of the invention will become more clearly understood from the following detailed description of the invention read together with the drawings in which: 
         FIG. 1  is an internal view of one embodiment of a rotary internal combustion engine; 
         FIG. 2  is a perspective view of one embodiment of a planetary rotor; 
         FIG. 3A  is a partial cross-sectional view of a planetary rotor; 
         FIG. 3B  is a partial cross-sectional view of a planetary rotor and a portion of the housing adjacent the pocket; 
         FIG. 4  is a partial front view of the planetary rotor at 12 degrees BTDC; 
         FIG. 5  is a partial front view of the planetary rotor at 9 degrees BTDC; 
         FIG. 6  is a partial front view of the planetary rotor at 6 degrees BTDC; 
         FIG. 7  is a partial front view of the planetary rotor at 3 degrees BTDC; 
         FIG. 8  is a partial front view of the planetary rotor at TDC; 
         FIG. 9  is a partial front view of the planetary rotor at 3 degrees ATDC; 
         FIG. 10  is a partial front view of the planetary rotor at 6 degrees ATDC; 
         FIG. 11  is a partial front view of the planetary rotor at 9 degrees ATDC; 
         FIG. 12  is a partial front view of the planetary rotor at 12 degrees ATDC; 
         FIG. 13  is a partial front view of the planetary rotor at 15 degrees ATDC; 
         FIG. 14  is a partial front view of the planetary rotor at 18 degrees ATDC; 
         FIG. 15  is a partial front view of the planetary rotor at 21 degrees ATDC; 
         FIG. 16  is a partial front view of the planetary rotor at 24 degrees ATDC; 
         FIG. 17  is a partial front view of the planetary rotor at 27 degrees ATDC; 
         FIG. 18  is a partial front view of the planetary rotor at 30 degrees ATDC; 
         FIG. 19  is a top view of another embodiment of a planetary rotor showing a pair of passages in the face of the rotor; and 
         FIG. 20  is a top view of still another embodiment of a planetary rotor showing another embodiment of a passage in the face of the rotor. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An apparatus for facilitating combustion in a rotary internal combustion engine  100  is disclosed. The illustrated engine  100  is a planetary piston rotary engine, such as that disclosed in U.S. Pat. Nos. 6,932,047 and 7,044,102, and in patent application Ser. No. 11/382,972, all incorporated by reference. In various embodiments, the rotary internal combustion engine  100  includes either compression ignition or spark ignition and includes fuel injection or other forms of introducing fuel into the engine  100 . 
       FIG. 1  illustrates an internal view of one embodiment of a rotary internal combustion engine  100 . The rotary internal combustion engine  100  includes a housing  104 , a main rotor  108 , and a plurality of planetary rotors  106 . The housing  104  has an internal cavity  124  in which rotates the main rotor  108 . The main rotor  108  has three cutouts  126  in which the planetary rotors  106  orbit about the main shaft  122 . 
     The internal cavity  124  is defined by three lobes  112 . Each pair of adjacent lobes  112  is joined at a bridge  114 . The main rotor  108  rotates clockwise  122  on the main shaft  110  inside the housing cavity  124 . The main rotor  108  has three circular cutouts  126  that each contain one planetary rotor  106 . The main rotor  108  also has three sections of outer rim  128  that engage the bridge  114  during selected positions of the main rotor  108  as the rotor  108  rotates inside the cavity  124 . 
     The planetary rotors  106  have three tips  130 . The surface between adjacent tips define a face  116  of the planetary rotor  106 . The planetary rotors  106  orbit in the clockwise direction  122  around the main shaft  110  inside the cutouts  126  of the main rotor  108 . As the planetary rotors  106  orbit, the rotors  106  do not rotate about their shaft  120 , but maintain a stationary position. That is, the face  116  of the planetary rotor  106  that faces upwards in  FIG. 1 , remains facing upward as the planetary rotor  106  orbits the main shaft  110 . The main shaft  110  and the planetary rotor shafts  120  are connected to a planetary gear assembly (not illustrated) that maintains the orbital position of the planetary rotors  106  as they orbit the main shaft  110 . 
     In the illustrated embodiment, the rotary internal combustion engine  100  has three fuel injectors  102 , one for each lobe  112 . In one such embodiment, the fuel injectors  102  are part of a high-pressure common rail direct injection system that provides fuel for combustion in the engine  100 . In other embodiments, the rotary internal combustion engine  100  receives fuel delivered through low pressure fuel injectors, from a carburetor, or by port injection. In various embodiments, fuel ignition occurs through compression or spark plug ignition. The fuel for the rotary internal combustion engine  100  ranges, in various embodiments, from heavy fuels to gasoline to ethanol to various flammable gases, for example, hydrogen gas. 
       FIG. 2  illustrates a perspective view of one embodiment of a planetary rotor  106 .  FIG. 3A  illustrates a partial cross-sectional view of the planetary rotor  106 . The planetary rotor  106  includes a rotor shaft  120  with a center axis  210 . Positioned equidistant from the center axis  210  of the planetary rotor  106  are three faces  116 . The planetary rotor  106  has three faces  116  that sequentially engage the lobes  112  of the housing  104 . As each face  116  engages successive lobes  112 , the face  116  sequentially plays a role in the cycle of intake, compression, combustion, and exhaust. Each face  116  is a multi-faceted face  202 ,  204 ,  206  that engages a bridge  114  during the transition from the compression cycle to the combustion cycle with the bridge  444   114  and face  116  forming a dynamic seal. In the illustrated embodiment, each face  116  includes a center section  204  that is flanked on each side by an arcuate surface  202 ,  206 . The arcuate surfaces  202 ,  206  extend to the tip seals  118 . Considering the direction  122  that the planetary rotors  106  orbit, one arcuate surface  202  is the trailing surface  202  and the other arcuate surface  206  is the leading surface  206  of each face  116 . 
     In the illustrated embodiment, the face  116  of the planetary rotor  106  that is opposite the fuel injector  102  when fuel is injected has a pocket  208 . In this way, the fuel cloud is able to expand without impinging or wetting the face  116  of the planetary rotor  106 . The leading surface  206  includes a depression, or combustion pocket,  208 . In the illustrated embodiment, the combustion pocket  208  has a triangular configuration with rounded corners when seen in a top view of the face  116 . In other embodiments, the combustion pocket  208  is positioned so as to accommodate the position of the planetary rotor  106  when firing or ignition of the fuel is desired. For example, the trailing corner of the pocket  208  is positioned in the center section  204  to accommodate a fuel injector nozzle  302  at a position closer to the center of the bridge  114  than illustrated in  FIG. 3B . 
     In one embodiment, the center section  204  of the face  116  is a flat surface. In one such embodiment, the flat surface of the center section  204  is parallel to the flat surface of the bridge  114  as the planetary rotor  106  orbits within the cavity  124 . In other embodiments, the center section  204  of the face  116  includes one or more curved surfaces. In one such embodiment, the surface of the center section  204  has a large radius such that the gap between the bridge  114  and the center section  204  is substantially constant as the planetary rotor  106  orbits past the bridge  114 . 
       FIG. 3B  illustrates a partial cross-sectional view of a planetary rotor  106  and a portion of the housing  104  adjacent the pocket  208 . Each fuel injector  102  terminates in a fuel injector nozzle  302  that has an end that is flush mounted in the housing  104 . The nozzle  302  directs a fan-shaped fuel cloud  304  into the space defined by the leading surface of the lobe  112 -L and the inside of the combustion pocket  208 . The pocket  208  provides a volume for the fuel cloud  304  to atomize without the fuel cloud  304  impinging on or wetting the surface of the planetary rotor face  116  or the surface of the lobe  112 -L. 
     In the illustrated embodiment, the combustion pocket  208  is deep at the leading end  208 -L to accommodate the expanding fuel cloud  304 . The pocket  208  is shallow at the trailing end  208 -T to minimize the volume of the combustion chamber while still allowing space for the fuel cloud  304  as the planetary rotor  106  orbits. The planetary rotor  106 , and the pocket  208 , move relative to the fuel injector nozzle  302  as the rotor  106  orbits. The triangular outline of the pocket  208 , as seen on the arcuate surface  206  of the planetary rotor face  116 , accommodates the fan-shaped fuel cloud  304 , which is narrowest and thinnest where the fuel exits the nozzle  302 . The shape and location of the pocket  208  is related to the location and position of the fuel injector nozzle  302 , as well as the direction and shape of the fuel cloud  304  from the nozzle  304 . 
     One embodiment of the tip seals  118  are identified in  FIG. 3B  as a leading seal  118 -L and a trailing seal  118 -T, considering the direction that the planetary rotor  106  orbits in the cavity  124 . The leading seal  118 -L slides along the lobe  112  such that the direction of relative travel of the surface of the lobe  112  is toward the trailing seal  118 -T. That is, the leading seal  118 -L, as illustrated in  FIG. 3B , is pushed along the surface of the lobe  112 . The trailing seal  118 -T slides along the lobe  112  such that the direction of relative travel of the surface of the lobe  112  is away from the leading seal  118 -L. That is, the trailing seal  118 -T is pulled across the surface of the lobe  112 . 
     The leading seal  118 -L has a deeper throat, or gap,  308 -L than the throat, or gap,  308 -T of the trailing seal  118 -T. Accordingly, the leading tab  306 -L is longer than the trailing tab  306 -T. The longer leading tab  306 -L and deeper gap  308 -L allows the tab  306 -L to flex or deform at a position close to the center of the tip of the planetary rotor  106 . The shorter trailing tab  306 -T and the shallower gap  308 -T allows the tab  306 -T to flex or deform at a position closer to the corner of the tip of the planetary rotor  106 . 
     The pushing of the leading seal  118 -L has a tendency to cause the leading tab  306 -L to flex or deform without undue stress on the tab  306 -L. That is, the leading seal  118 -L moving along the lobe  112  tends to push or force the tab  306 -L toward the planetary rotor  106 , thereby tending to close the gap  308 -L. The pulling of the shorter trailing seal  118 -T has a tendency to push or force the trailing tab  306 -T away from the planetary rotor  106 , which, if the trailing tab  306 -T were longer, would result in a longer lever arm and greater stress on the connection of the trailing tab  306 -T to the planetary rotor  106 . 
     In the illustrated embodiment, the tip seal  118  of the planetary rotor  106  includes a tab  306  that is separated from the body of the rotor  106  by a gap  308 . The tab  306  resiliently moves when the tab  306  contacts a lobe  112 . When the planetary rotor  106  orbits the main shaft  110 , at least one tip seal  118  is in contact with a lobe  112 . The resilience of the tab  306  accommodates manufacturing tolerances, thermal expansion, and irregularities in the surface of the lobe  112 . The gap  308  is on the side of the tab  306  that is subject to high pressure, for example, when the trailing tip seal  118 -T defines a portion of the compression chamber  408  or the leading tip seal  118 -L defines a portion of the combustion chamber  410 , as illustrated in  FIGS. 4 to 18 . The high pressure in the gap  308  applies force to the inside surface of the tab  306 , thereby pushing the tab  306  away from the gap  308  and against the surface of the lobe  112 . The greater the pressure, the greater the force pushing the tab  306  against the surface of the lobe  112  and the better the seal. The outside surface of the tab  306  is rounded to accommodate the various orientations of the surface of the lobe  112  when the lobe  112  is in contact with the tab  306 . 
       FIGS. 4 through 18  illustrate the position of the planetary rotor  106  relative to the housing  104  and bridge  114  as the planetary rotor  106  orbits about the main shaft  110 . When the planetary rotor  106  orbits 360 degrees inside the cavity  124 , each of the faces  116  is exposed sequentially to intake, compression, combustion, and exhaust. The compression chamber  408  progressively decreases in volume and the combustion chamber  410  increases in volume as the planetary rotor  106  orbits. 
     The figures illustrate the planetary rotor  106  relative to TDC. Top dead center (TDC) is defined as the position of the planetary rotor  106  where the radial bridge center  404  is aligned, or coincides, with the radial planetary rotor center  402 . That is, TDC is the position of the planetary rotor  106  in relation to the bridge  114  where the illustrated lines labeled  402 ,  404 ,  408  coincide. In other words, at TDC a line passes through the center of the bridge  114 , the center of the planetary rotor  106 , and the center of the main rotor  108 . 
     The radial bridge center  404  is illustrated as a line passing through the center of rotation of the main shaft  110  and the center of the bridge  114 . The radial planetary rotor center  402  is illustrated as a line passing through the center of rotation of the main shaft  110  and the center axis  210  of the planetary rotor  106 . The center  408  of the planetary rotor face  116  is illustrated as a line passing through the center of one face  116  of the planetary rotor  106  and the center axis  210  of the planetary rotor  106 . As the planetary rotor  106  orbits, the center  408  of the planetary rotor face  116  approaches the radial bridge center  404  BTDC, coincides with the radial bridge center  404  at TDC, and moves away from radial bridge center  404  ATDC. 
       FIG. 4  illustrates a partial front view of the planetary rotor  106  at 12 degrees BTDC (before top dead center), that is, the radial planetary rotor center  402 − 12  forms a 12 degree angle  406 − 12  with the radial bridge center  404 . 
     In the configuration illustrated in  FIG. 4 , a compression chamber  408  is defined by the surface of the trailing lobe  112 -T, the face  116  of the planetary rotor  106 , the bridge  114 , and one tip seal  118 -T. The trailing arcuate surface  202  and the center section  204  of the face  116  of the planetary rotor  106  define one surface of the compression chamber  408 . A combustion chamber  410  is defined by the surface of the leading lobe  112 -L, the leading arcuate surface  206  of the face  116  of the planetary rotor  106 , and one tip seal  118 -L. 
     Compressed gas flows from the compression chamber  408  to the combustion chamber  410  through the slot, or gap, between the bridge  114  and the face  116  of the planetary rotor  106 . The gap between the bridge  114  and the leading arcuate surface  206  of the face  116  also includes a portion of the combustion pocket  208 . 
       FIG. 5  illustrates a partial front view of the planetary rotor  106  at 9 degrees BTDC, that is, the radial planetary rotor center  402 − 9  forms a 9 degree angle  406 − 9  with the radial bridge center  404 . The distance between the center  408  of the planetary rotor face  116  and the radial bridge center  404  is less than that illustrated in  FIG. 4  as the planetary rotor  106  continues in its orbit and approaches TDC. 
     The compression chamber  408  is defined by the surface of the trailing lobe  112 -T, the face  116  of the planetary rotor  106 , the bridge  114 , and one tip seal  118 -T. The compression chamber  408  continues decreasing in volume while the combustion chamber  410  increases in volume. Compressed gas continues to flow from the compression chamber  408  to the combustion chamber  410  through the slot, or gap, between the bridge  114  and the face  116  of the planetary rotor  106 . The gap between the bridge  114  and the leading arcuate surface  206  of the face  116  also includes a decreasing portion of the combustion pocket  208 . The flow from the compression chamber  408  to the combustion chamber  410 , because of the slot and combustion pocket  208 , causes turbulent flow in the combustion chamber  410 . 
       FIG. 6  illustrates a partial front view of the planetary rotor  106  at 6 degrees BTDC, that is, the radial planetary rotor center  402 − 6  forms a 6 degree angle  406 − 6  with the radial bridge center  404 . The distance between the center  408  of the planetary rotor face  116  and the radial bridge center  404  continues to decrease as the planetary rotor  106  continues in its orbit and approaches TDC. 
     The compression chamber  408  is now defined by the surface of the trailing lobe  112 -T, the face  116  of the planetary rotor  106 , and one tip seal  118 -T. The compression chamber  408  continues decreasing in volume while the combustion chamber  410  increases in volume. 
     The center section  204  of the face  116  of the planetary rotor  106  moves adjacent to the surface of the bridge  114 . In the illustrated embodiment, the center section  204  is parallel with the surface of bridge  114 . Without combustion in the combustion chamber  410 , compressed gas continues to flow from the compression chamber  408  to the combustion chamber  410  through the slot, or gap, between the bridge  114  and the face  116  of the planetary rotor  106 . The gap between the bridge  114  and the leading arcuate surface  206  of the face  116  also includes a small portion of the combustion pocket  208 . The flow from the compression chamber  408  to the combustion chamber  410 , because of the slot and combustion pocket  208 , continues to cause turbulent flow in the combustion chamber  410 . 
     Injection and combustion of fuel is based on various factors. In a reciprocating piston engine, a negative torque is generated when fuel is combusted before TDC. In the illustrated embodiment, a positive torque is generated when combustion occurs in the combustion chamber  410  with the planetary rotor  106  approaching TDC. Although the illustrated embodiment shows the planetary rotor  106  at the six degrees BTDC position, combustion can be initiated at other positions of the planetary rotor  106 , depending upon engine requirements and power needs. The combustion of the fuel in the combustion chamber  410  causes a force to be applied to the face  116  of the planetary rotor  106 . That force is represented by the illustrated force vector  602 . The force vector  602  on the planetary rotor  106  is aligned generally with the direction  122  of rotation of the main rotor  108  and the direction of orbit of the planetary rotor  106 . That is, the moment arm created by the force vector  602  serves to move the main rotor  108  in the direction  122  of rotation. 
     In one embodiment, the fuel is introduced initially into the combustion chamber  410  with a short burst from the fuel injector  102  at around six degrees BTDC. The initial burst of fuel from the fuel injector  102  is followed by other bursts of fuel and, between the bursts, compressed gas from the compression chamber  408  flows into the combustion chamber  410  with jet flow, thereby creating turbulence in the combustion chamber  410  and promoting more efficient combustion of the fuel. 
     In other embodiments, the fuel is introduced into the engine  100  by mixing with the intake air, such as with a carburetor. In various embodiments, the fuel mixture is ignited by one or more ignition sources, for example, spark plugs, laser energy, or injection of an externally ignited combustible mass, or by compression of the fuel mixture 
       FIG. 7  illustrates a partial front view of the planetary rotor  106  at 3 degrees BTDC, that is, the radial planetary rotor center  402 − 3  forms a 3 degree angle  406 − 3  with the radial bridge center  404 . The distance between the center  408  of the planetary rotor face  116  and the radial bridge center  404  continues to decrease as the planetary rotor  106  continues in its orbit and approaches TDC. 
     The center section  204  of the face  116  of the planetary rotor  106  is aligned with the surface of the bridge  114  and forms a small gap between the center section  204  and the bridge  114 . Compressed gas continues to flow from the compression chamber  408  to the combustion chamber  410  through the slot, or gap, between the bridge  114  and the face  116  of the planetary rotor  106 . The flow of compressed gas from the compression chamber  408  into the combustion chamber  410  continues only as long at the pressure in the compression chamber is greater than that in the combustion chamber  410 . After combustion begins, the narrow gap between the center  408  of the planetary rotor face  116  and the radial bridge center  404  is sufficient to quench the flame front and prevents the propagation of the combustion flame from the combustion chamber  410  into the compression chamber  408 . 
     The face  116  of the planetary rotor  106  engages the bridge  114  during the transition from the compression cycle to the combustion cycle such that the bridge  114  and face  116  have a gap that allows gas flow from the trailing volume  408  to the leading volume  410  and the gap is sufficiently small to quench flame propagation from the leading volume  410  to the trailing volume  408 . In this way, turbulence is introduced into the leading volume  410  of a rotary engine  100  during the period that the fuel is introduced into the leading volume  410  without encouraging flame propagation from the leading volume  410  to the trailing volume  408 . 
       FIG. 8  illustrates a partial front view of the planetary rotor  106  at TDC (top dead center), that is, the radial planetary rotor center  402 − 0  coincides (forms a 0 degree angle  406 − 0 ) with the radial bridge center  404 . The surface of the bridge  114  is centered in the center section  204  of the face  116  of the planetary rotor  106 . In the illustrated embodiment, the gap between the center section  204  and the bridge  114  is at its smallest size when the planetary rotor  106  is at TDC. 
     At this position, combustion in the combustion chamber  410  results in a force vector  602  that applies ever greater force/torque for causing the main rotor  108  to rotate. 
       FIG. 9  illustrates a partial front view of the planetary rotor  106  at 3 degrees ATDC (after top dead center), that is, the radial planetary rotor center  402 + 3  forms a positive 3 degree angle  406 + 3  with the radial bridge center  404 . The surface of the bridge  114  continues to move along the center surface  204  of the face  116  of the planetary rotor  106  with the gap between the bridge  114  and the face  116  increasing. 
       FIG. 10  illustrates a partial front view of the planetary rotor  106  at 6 degrees ATDC, that is, the radial planetary rotor center  402 + 6  forms a positive 6 degree angle  406 + 6  with the radial bridge center  404 . The surface of the bridge  114  continues to move along the center surface  204  of the face  116  toward the trailing arcuate surface  202  of the planetary rotor  106 . The gap between the bridge  114  and the face  116  continues to increase and the volume of the compression chamber  408  continues to decrease. 
       FIG. 11  illustrates a partial front view of the planetary rotor  106  at 9 degrees ATDC, that is, the radial planetary rotor center  402 + 9  forms a positive 9 degree angle  406 + 9  with the radial bridge center  404 . The bridge  114  begins moving off the center section  204  and along the trailing arcuate surface  202  of the face  116  of the planetary rotor  106 . 
     As the planetary rotor  106  orbits, the main rotor  108  rotates at the same speed. The planetary rotor  106  moves within the circular cutout  126  of the main rotor  108 .  FIG. 11  illustrates the inside surface of the circular cutout  126  beginning to move toward the trailing tip seal  118 -T. 
       FIG. 12  illustrates a partial front view of the planetary rotor  106  at 12 degrees ATDC, that is, the radial planetary rotor center  402 + 12  forms a positive 12 degree angle  406 + 12  with the radial bridge center  404 . The compression chamber  408  has a volume that contains very little gas. 
       FIG. 13  illustrates a partial front view of the planetary rotor  106  at 15 degrees ATDC, that is, the radial planetary rotor center  402 + 15  forms a positive 15 degree angle  406 + 15  with the radial bridge center  404 . The inside surface of the circular cutout  126  begins to move adjacent a tip seal  118 . 
       FIG. 14  illustrates a partial front view of the planetary rotor  106  at 18 degrees ATDC, that is, the radial planetary rotor center  402 + 18  forms a positive 18 degree angle  406 + 18  with the radial bridge center  404 . The inside surface of the circular cutout  126  begins to move toward the trailing tip seal  118 -T and the outer rim  128  of the main rotor  108  approaches the inside surface of the housing  104 . 
       FIG. 15  illustrates a partial front view of the planetary rotor  106  at 21 degrees ATDC, that is, the radial planetary rotor center  402 + 21  forms a positive 21 degree angle  406 + 21  with the radial bridge center  404 . The inside surface of the circular cutout  126  begins to move toward the trailing tip seal  118 -T and the outer rim  128  of the main rotor  108  approaches the inside surface of the housing  104 . 
       FIG. 16  illustrates a partial front view of the planetary rotor  106  at 24 degrees ATDC, that is, the radial planetary rotor center  402 + 24  forms a positive 24 degree angle  406 + 24  with the radial bridge center  404 . The outer rim  128  of the main rotor  108  approaches the bridge  114  and the trailing tip seal  118 -T is about to move off of the trailing lobe  112 -T. 
       FIG. 17  illustrates a partial front view of the planetary rotor  106  at 27 degrees ATDC, that is, the radial planetary rotor center  402 + 27  forms a positive 27 degree angle  406 + 27  with the radial bridge center  404 . The outer rim  128  of the main rotor  108  engages the surface of the bridge  114  and the trailing tip seal of the planetary rotor  106  no longer forms a seal with the inside surface of the housing  104 . 
     In the illustrated embodiment, the outer rim  128  does not contact the surface of the bridge  114 , but the outer rim  128  moves past the bridge  114  with a very small air gap between the two surfaces  128 ,  114 . The gap between the two surfaces  128 ,  124  is small enough that the pressure of the combustion gases in the combustion chamber  410  is not sufficient to cause an appreciable amount of combustion gases to exit the combustion chamber  410  through the gap. 
       FIG. 18  illustrates a partial front view of the planetary rotor  106  at 30 degrees ATDC, that is, the radial planetary rotor center  402 + 30  forms a positive 30 degree angle  406 + 30  with the radial bridge center  404 . The outer rim  128  of the main rotor  108  continues to move past the surface of the bridge  114 . The combustion chamber  410  is defined by the surface of the leading lobe  112 -L, the face  116  of the planetary rotor  106 , one tip seal  118 -L, and the inside surface of the circular cutout  126 . At this position of the planetary rotor  106  in its orbit, combustion is occurring in the combustion chamber  410  and the combustion gases are expanding. 
       FIG. 19  illustrates a top view of another embodiment of a planetary rotor  106 ′ showing a pair of passages  1902 -A in the face  116 . The passages  1902  are grooves in the face  116  of the planetary rotor  106 ′. When the center section  204  of the face  116  of the planetary rotor  106 ′ is adjacent the bridge  114 , such as illustrated in  FIGS. 6-10 , the passages  1902  provide a path for the compressed gas in the compression chamber  408  to flow into the combustion chamber  410 . 
     In the illustrated embodiment, two passages  1902 -A are positioned on one side of the face  116  and connect the trailing arcuate surface  202  with the leading arcuate surface  206  across the center section  204 . Because the passages  1902  are positioned asymmetrically, the flow of high pressure gas into the combustion chamber  410  creates turbulence in the combustion chamber  410 , which aids in the mixing of the fuel cloud  304  in the combustion chamber  410 , which aids in the combustion of that fuel cloud  304 . In another embodiment, the passages  1902  connect to the combustion pocket  208 . The size, depth, and position of the passages  1902  are determined by the amount and timing of gas flow from the compression chamber  408  to the combustion chamber  410  desired for operation of the engine  100 . 
     The passages  1902 -A illustrated in  FIG. 19  connect the compression chamber  408  to the combustion chamber  410  by allowing a fluid path between the trailing surface  202  and the leading surface  206  of the face  116  of the planetary rotor  106 ′. The illustrated configuration may cause combustion gases to flow into the compression chamber  410  if the pressure in the combustion chamber  410  exceeds the pressure of the compression chamber  408 . Accordingly, the position of the ends of the passages  1902 -A determines the direction of flow along the passages  1902 -A. 
       FIG. 20  illustrates a top view of still another embodiment of a planetary rotor  106 ″ showing a passage, or groove,  1902 -B in the face  116 . The position of the passage  1902 -B connects the trailing surface  202  and the center section  204  such that, as the planetary rotor  106 ″ orbits past the bridge  114 , the pressure in the compression chamber  408  increases until, where the bridge  114  exposes the leading edge of the passage  1902 -B the pressure is greater than the pressure in the combustion chamber  410 , thereby allowing the gas in the compression chamber  408  to flow into the combustion chamber  410 . The angled configuration of the passage  1902 -B directs the flow from the compression chamber  408  into the combustion chamber  410  at an angle, thereby aiding in mixing the gas in the combustion chamber  410 . 
     The various components of the rotary internal combustion engine  100  perform various functions. The function of sealing the connection between the planetary rotor  106  and the lobes  112  is implemented, in one embodiment, by the tip seals  118 . In one embodiment, the tip seals  118  include a resilient tab  306  that rides against the surface of the lobe  112  to contain compressed gases. Under the tab  306  is a gap  308  that is exposed to high pressure, which forces the tab  306  away from the gap  308  and against the surface of the lobe  112 . 
     The function of sealing the connection between the lobe  112  and the main rotor  108  is implemented, in one embodiment, by the surface of the bridge  114  engaging the outer rim  128  of the main rotor  108 , which creates a dynamic seal, not a mechanical seal. The surface of the bridge  114  and the outer rim  128  are separated by a small air gap. The air gap is not sufficiently large to allow an appreciable amount of high pressure gas to flow through the air gap. 
     The function of creating turbulent flow conditions in the combustion chamber  410  is implemented, in one embodiment, by the bridge  114  engaging the face  116  of the planetary rotor  106 , which causes a narrow slot to be formed between the bridge  114  and the face  116 . When the pressure in the compression chamber  408  is sufficiently higher than the pressure in the combustion chamber  410 , the compressed gas inside the compression chamber  408  flows through the narrow slot into the combustion chamber  410 . The jet flow from the narrow slot creates a turbulent condition inside the combustion chamber  410 . In another embodiment, passages  1902 -A,  1902 -B in the face  116  of the planetary rotor  106 ′,  106 ″ allow the compressed gas inside the compression chamber  408  to flow past the bridge  114  into the combustion chamber  410  in an asymmetrical manner, thereby creating turbulence in the combustion chamber  410 . 
     The function of avoiding impingement of fuel is implemented, in one embodiment, by the combustion pocket  208 , which is a depression in the face  116  of the planetary rotor  106 . The face  116  has a leading surface  206 , which is one defining surface of the combustion chamber  410 . In one embodiment, the combustion pocket  208  has a triangular shape that corresponds to the fan-shaped fuel cloud  304  emitted by the fuel injector nozzle  302 . 
     From the foregoing description, it will be recognized by those skilled in the art that combustion chamber elements for a rotary internal combustion engine  100  have been provided. The engine  100  includes lobes  112  joined with bridges  114  that protrude into a cavity  124  in the engine housing  104 . Inside the cavity  124  is a main rotor  108  that includes circular cutouts  126 . Inside each circular cutout  126  is a planetary rotor  106  that has faces  116  positioned about the circumference of the planetary rotor  106 . The faces  116 , the lobes  112 , and the bridges  114  sequentially define a compression chamber  408  and a combustion chamber  410 . As combustion proceeds and the main rotor  108  rotates, an outer rim  128  of the main rotor  108  forms a seal with the bridge  114  to further contain the combustion gases. 
     While the present invention has been illustrated by description of several embodiments and while the illustrative embodiments have been described in considerable detail, it is not the intention of the applicant to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and methods, and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.