Abstract:
An internal combustion engine including a housing, an intake port defined in the housing, an exhaust port defined in the housing, and a generally cylindrical combustion chamber defined in the housing. The combustion chamber communicates with the intake port and the exhaust port and a combustion geroter is received by and rotatable within the combustion chamber. During operation, the combustion geroter receives a fuel mixture, compresses the fuel mixture, combusts the fuel mixture, and discharges the combusted fuel mixture to the exhaust port.

Description:
FIELD OF THE INVENTION 
   The invention relates to internal combustion engines, and more particularly to two-cycle rotary internal combustion engines. 
   BACKGROUND 
   Many types and configurations of internal combustion engines are well known in the art. Many modern internal combustion engines operate on either a two-cycle operating sequence, or a four-cycle operating sequence. Some internal combustion engines are of the reciprocating piston type and include one or more pistons coupled to a crankshaft for reciprocation within an engine cylinder. Other internal combustion engines are of the rotary or “Wankel” type, and include a rotating piston element. Different combinations of engine operating cycles and engine configurations have been developed and utilized for a variety of applications. 
   SUMMARY OF THE INVENTION 
   The present invention provides an internal combustion engine including a housing, an intake port defined in the housing, an exhaust port defined in the housing, and a generally cylindrical combustion chamber defined in the housing. The combustion chamber communicates with the intake port and the exhaust port. The engine also includes a combustion geroter received by and rotatable within the combustion chamber. During operation, the combustion geroter receives a fuel mixture, compresses the fuel mixture, combusts the fuel mixture, and discharges the combusted fuel mixture to the exhaust port. 
   The internal combustion engine can also include a generally cylindrical compression chamber that is also defined in the geroter housing and communicates with the intake port. An intermediate manifold can be formed in the housing for communication between the compression chamber and the combustion chamber. A compressor geroter can be received by and rotatable within the compression chamber. During operation, the compressor geroter receives the fuel mixture from the intake port, compresses the fuel mixture, and discharges the compressed fuel mixture to the intermediate manifold. The engine can also include a drive shaft coupling the compressor geroter and the combustion geroter for rotation together. The engine is configured such that the combustion geroter receives the compressed fuel mixture from the intermediate manifold. 
   The present invention also provides a method for rotatably driving a drive shaft. The method includes providing a geroter having an inner gear coupled to the drive shaft and an outer gear engaging the inner gear. A fuel mixture is delivered to the geroter, compressed in the geroter, combusted in the geroter, expanded in the geroter, thereby drivingly rotating the geroter and the drive shaft, and discharged from the geroter. 
   Other features of the invention will become apparent to those skilled in the art upon review of the following detailed description, claims, and drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a section view of a two-cycle geroter engine embodying the invention. 
       FIG. 2  is a section view taken along line  2 — 2  of  FIG. 1 . 
       FIG. 3  is a section view taken along line  3 — 3  of  FIG. 1 . 
       FIG. 4  is a section view taken along line  4 — 4  of  FIG. 1 . 
       FIG. 5  is a section view taken along line  5 — 5  of  FIG. 1 . 
   

   Before one embodiment of the invention is explained in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced or being carried out in various ways. Also, it is understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
   DETAILED DESCRIPTION 
     FIG. 1  illustrates a two-cycle geroter internal combustion engine  10  of the present invention. The engine  10  includes an engine geroter housing  14  that defines a compression chamber  18  and a combustion chamber  22 . The housing  14  also defines an intake port  26  that communicates with the compression chamber  18 , and an exhaust port  30  that communicates with the combustion chamber  22 . An intermediate manifold  34  is also defined by the housing  14  and communicates between the compression chamber  18  and the combustion chamber  22 . 
   Referring also to  FIGS. 2 and 3 , an upstream compressor geroter  38  is rotatably received by the geroter housing  14  within the compression chamber  18 . The compressor geroter  38  includes an outer gear  42  that defines a geroter chamber  46 , and an inner gear  50  that is received by the geroter chamber  46 . As illustrated, the geroter chamber  46  is generally star shaped and includes five convex surfaces  54 . The inner gear  50  includes four concave surfaces  58  that cooperate with the convex surfaces  54  to define four charge chambers  62 . 
   During engine operation, the inner gear  50  rotates about a first axis  66 , and the outer gear  42  rotates about a second axis  70  that is spaced from and is substantially parallel to the first axis  66 . The surfaces of the inner and outer gears  50 ,  42  slidingly and rollingly engage each other as the gears  50 ,  42  rotate with respect to the geroter housing  14  such that the charge chambers  62  increase and decrease in volume while orbiting the first and second axes  66 ,  70 . Specifically, for each rotation of the inner gear  50 , an individual charge chamber  62  decreases from a maximum volume (illustrated in the 12 o&#39;clock position in  FIGS. 2 and 3 ) to a minimum volume (illustrated in the 6 o&#39;clock position in  FIGS. 2 and 3 ), and then increases back to the maximum volume. Thus, for clockwise rotation of the inner and outer gears  50 ,  42  of  FIGS. 2 and 3 , the charge chamber  62   a  in the 3 o&#39;clock position is decreasing in volume, and the charge chamber  62   b  in the 9 o&#39;clock position is increasing in volume. Because the inner gear  50  includes four concave surfaces  58  and the outer gear  42  includes five convex surfaces  54 , the inner gear  50  rotates faster than the outer gear  42  during engine operation. 
   It should be appreciated that the inner and outer gears  50 ,  42  could be alternatively configured to include a different number of concave and convex surfaces. Generally, the outer gear  42  will include N convex surfaces, and the inner gear  50  will include N-1 concave surfaces. However, the configuration of the gears could be altered such that the outer gear  42  includes N concave surfaces and the inner gear  50  includes N-1 convex surfaces. The specific number of convex/concave surfaces and the resultant number of charge chambers are determined by the specific application for which the engine is to be utilized. The various geroter modifications and variations described above are presumed to be well known in the art, and therefore provide a number of foreseeable equivalent geroter configurations that will function and operate in substantially the same way as the embodiments described in further detail herein. 
   The intake port  26  includes an intake aperture  74  that opens into the compression chamber  18  (see  FIG. 2 ). The intake aperture  74  may be kidney-shaped and is positioned to communicate with the charge chambers  62  when the charge chambers  62  are increasing in volume. Similarly, the intermediate manifold  34  includes an outlet aperture  78  that also opens into the compression chamber  18  (see  FIG. 3 ). Unlike the intake aperture  74 , the outlet aperture  78  is positioned to communicate with the charge chambers  62  when the charge chambers  62  are decreasing in volume. This arrangement generally results in the intake aperture  74  being positioned on one side of a plane that extends through the first and second axes  66 ,  70 , and the outlet aperture  78  being positioned on an opposite side of the plane extending through the first and second axes  66 ,  70 . Like the intake aperture  74 , the outlet aperture  78  may be kidney-shaped. 
   During engine operation, as an individual charge chamber  62  increases in volume, a pressure differential is created that draws a charge of fuel mixture (or at least a portion of a charge of fuel mixture) from the intake port  26  into the charge chamber  62 . Communication between the charge chamber  62  and the intake port  26  is cut-off as the charge chamber  62  reaches a position generally associated with the charge chamber  62  reaching a maximum volume (e.g. near the 12 o&#39;clock position in  FIGS. 2 and 3 ). At substantially the same or at a slightly advanced position, the charge chamber  62  begins to decrease in volume and moves into communication with the outlet aperture  78 . The charge of fuel mixture is therefore discharged through the outlet aperture  78  and into the intermediate manifold  34 . As the charge chamber  62  continues decreasing in volume, the charge is compressed within the intermediate manifold  34  to an elevated pressure. As the charge chamber  62  reaches and moves past a position generally associated with a minimum volume, communication with the outlet aperture  78  is cutoff, and communication with the intake aperture  74  is reestablished. Another charge of fuel mixture is then drawn into the charge chamber  62  and subsequently compressed and discharged into the intermediate manifold  34 . 
   Referring also to  FIGS. 4 and 5 , a combustion geroter  82  is also rotatably received by the geroter housing  14  within the combustion chamber  22 . The illustrated combustion geroter  82  is configured similarly to the compressor geroter  38  and includes an outer gear  86  and an inner gear  90  that is received by the outer gear  86 . The outer gear  86  includes five convex surfaces  94 , and the inner gear  90  includes four concave surfaces  98  that cooperate with the convex surfaces  94  to define four ignition chambers  102  that are similar to the charge chambers  62 . The inner gear  90  of the combustion geroter  82  is coupled to the inner gear  50  of the compressor geroter  38  by a drive shaft  104  for drivingly rotating the compressor geroter  38 . In the illustrated embodiment, the drive shaft  104  and the inner gear  90  rotate about the first axis  66 , and the outer gear  86  rotates about the second axis  70 . However, the engine is not limited to this configuration, as will be discussed further below. 
   The surfaces of the inner and outer gears  90 ,  86  slidingly and rollingly engage each other as the gears  90 ,  86  rotate such that the ignition chambers  102  increase and decrease in volume while orbiting the first and second axes  66 ,  70 . For clockwise rotation of the combustion geroter  82  of  FIGS. 4 and 5 , ignition chambers  102  to the right of the first and second axes  66 ,  70  are decreasing in volume, and ignition chambers  102  to the left of the first and second axes  66 ,  70  are increasing in volume. Operation of the combustion geroter  82  is in many ways analagous to the operation of the compressor geroter. It should therefore be appreciated that the variations and alternative configurations discussed above with respect to the compressor geroter  38  also apply to the combustion geroter  82 . 
   The intermediate manifold  34  communicates with the combustion chamber  22  through a charge inlet aperture  106 . With respect to  FIG. 4 , the inlet aperture  106  may be kidney-shaped and is positioned to communicate with the ignition chambers  102  from a point just before the ignition chambers  102  reach maximum volume (e.g. the 12 o&#39;clock position in  FIG. 4 ) until the ignition chambers  102  have decreased in volume to an intermediate volume (e.g. approximately the 2 o&#39;clock position in  FIG. 4 ). The exhaust port  30  communicates with the combustion chamber  22  through an exhaust aperture  110 . The exhaust aperture  110  may be kidney-shaped and is positioned to communicate with the ignition chambers  102  from a point where the ignition chambers  102  are increasing in volume (e.g. approximately the 9:30 position in  FIGS. 4 and 5 ), until the ignition chambers  102  reach maximum volume. As illustrated, there is a period during ignition chamber movement wherein the exhaust aperture  110  and the inlet aperture  106  are in simultaneous communication with the ignition chamber  102 . This period is known as the “overlap” and is a feature that is common among two-cycle internal combustion engines, regardless of the type of engine configuration (e.g. reciprocating piston or rotary) that is employed. The overlap area is indicated by the reference character “O” in  FIG. 4 . 
   The relative positioning of the inlet aperture  106  and the exhaust aperture  110  provides an appropriate arrangement for operation of the combustion geroter  82  as a two-cycle internal combustion engine. As an individual ignition chamber  102  approaches a position associated with a maximum volume, communication between the ignition chamber  102  and the intermediate manifold  34  is established. The charge of fuel mixture that was previously compressed into the intermediate manifold  34  by the compressor geroter  38  begins to flow into the ignition chamber  102 . As with conventional two-cycle engines, fluid momentum of the fuel mixture and backpressure in the exhaust port  30  allow the charge of fuel mixture to enter the ignition chamber  102  even as the ignition chamber is decreasing in volume. As the combustion geroter  82  continues to rotate, the ignition chamber  102  moves to a position wherein communication with the intermediate manifold  34  is cut off, and the pre-compressed fuel mixture is further compressed in preparation for ignition of the fuel mixture. 
   In the illustrated embodiment, ignition of the fuel mixture occurs before the ignition chamber  102  reaches minimum volume, approximately at the position indicated by the reference character “I” in  FIG. 4 . Of course the exact moment at which ignition of the fuel mixture occurs can vary (even during engine operation) and is largely determined by engine size, fuel type, operating speed, and other parameters, as will be readily apparent to those of ordinary skill in the art. The internal combustion engine  10  of the present invention can be adapted for use as a spark-ignition engine, and as a compression-ignition engine (e.g. a diesel engine). For use as a spark-ignition engine, a spark plug hole (not shown) is provided in the geroter housing  14  and a spark plug is inserted therein such that a spark plug electrode is appropriately positioned in the combustion chamber to ignite the fuel mixture. Voltage can be provided to the spark plug in a known manner using ignition coils and the like. The firing of the spark plug can also be timed in a known manner using known devices such as distributors or electronic control modules, for example. For use as a compression-ignition engine, the relative sizes of the geroters  38 ,  82 , the inner gears  50 ,  90  and the outer gears  42 ,  86  are selected such that, when using diesel fuel, the pressure increase (and resultant temperature increase) during the final charge compression in the combustion geroter  82  is sufficient to ignite the fuel mixture when the ignition chamber  102  is in the appropriate position. 
   After the charge has been ignited, the charge and the ignition chamber  102  begin to expand. The expanding charge urges the concave surface  98  of the inner gear  90  away from the convex surface  94  of the outer gear  86 , which in turn drivingly rotates the combustion geroter  82  (and also the compressor geroter  38  by way of the drive shaft  104 ) in a clockwise direction as illustrated in  FIGS. 2–5 . As the ignition chamber  102  expands and moves toward the 12 o&#39;clock position, communication is established with the exhaust aperture  110 . The expanding fuel charge begins to flow out of the ignition chamber  102 , through the exhaust aperture  110 , and into the exhaust port  30 . When the ignition chamber  102  reaches maximum volume, communication has also been established with the inlet aperture  106  due to the overlap area O discussed above. If the operating conditions are appropriate, the momentum of the combusted fuel charge that is exiting the ignition chamber  102  creates a slight vacuum in the ignition chamber  102 , which can assist in drawing a fresh charge of fuel mixture into the ignition chamber  102  through the inlet aperture  106 . Upon further rotation of the combustion geroter  82 , communication between the ignition chamber  102  and the exhaust aperture  110  is cutoff, and the combustion cycle is repeated using the fresh charge of fuel mixture. 
   As thus far described, the engine  10 , including the combustion geroter  82  which drivingly rotates the compressor geroter  38  by way of the drive shaft  104 , can be reasonably categorized as a supercharged two-cycle engine. With specific reference to  FIG. 1 , the compressor geroter  38  has a greater length in the axial direction than the combustion geroter  82 . As a result, the maximum volume of an individual charge chamber  62  is greater than the maximum volume of an individual ignition chamber  102 . The relative volumes of the charge chambers  62  and the ignition chambers  102  can be selected to establish the amount of fuel mixture pre-compression or “boost” provided by the compressor geroter  38 . While the illustrated engine  10  accomplishes this by providing a compressor geroter  38  of greater axial length than the combustion geroter  22 , similar results could be achieved by increasing the diameter of the compressor geroter  38  with respect to the combustion geroter  22 . 
   As discussed above and illustrated in the Figures, the inner gears  50 ,  90  of both the compressor geroter  38  and the combustion geroter  82  include four concave surfaces  58 ,  98  each. Thus, for one complete revolution of the engine  10 , there are four combustion events, one combustion event occurring in each ignition chamber  102  per inner gear revolution. Also, by comparing  FIGS. 3 and 4 , it can be seen that the charge of fuel mixture that is expelled from the charge chamber  62  in the 3 o&#39;clock position is being communicated to the ignition chamber  102  that is in the 12 o&#39;clock position via the intermediate manifold  34 . 
   It should be appreciated that the invention is not limited to these specific configurations. For example, the illustrated geroters  38 ,  82  can be considered to be “in phase” because the positions corresponding to the maximum volumes of the charge chambers  62  and the ignition chambers  102  (e.g. the 12 o&#39;clock positions) are substantially radially aligned. It should be appreciated that the geroters  38 ,  82  can be shifted to different radial positions with respect to each other. Such shifting would generally result in a reconfiguration of the intermediate manifold  34 , which might extend through the geroter housing  14  in a different manner than that illustrated in the Figures. Also, the compressor geroter  38  and the combustion geroter  82  need not necessarily have the same number of charge chambers  62  and ignition chambers  102 . Either geroter  38 ,  82  can be configured to provide with more or fewer chambers  62 ,  102  depending upon the specific application and desired power characteristics of the engine  10 . 
   In addition to being radially aligned, in the illustrated embodiment, the combustion geroter  82  is also substantially axially aligned with the compressor geroter  38 . Specifically, the inner gears  50 ,  90  both rotate about the first axis  66 , and the outer gears  42 ,  86  both rotate about the second axis  70 . It should be understood that the present invention is not limited with respect to the arrangement and alignment of the compressor geroter  38  and the combustion geroter  82 . For example, the geroters  38 ,  82  can be positioned to lie in substantially the same plane (e.g. the plane defined by section line  3 — 3  in  FIG. 1 ) and the inner gears  50 ,  90  can be drivingly coupled to each other using differently configured drive shafts that can include belts, pulleys, gears, chains, and substantially any other type of coupling. Additional configurations that position the geroters  38 ,  82  at angles with respect to each other are also foreseeable. In this regard, an arrangement of bevel gears could be employed to drivingly couple the geroters  38 ,  82  to each other. Of course, each variation on the positioning of the geroters  38 ,  82  will result in a reconfiguration of the intermediate manifold  34  and the apertures  74 ,  78 ,  102 ,  106  such that appropriate fluid communication is maintained between the compressor chamber  18  and the combustion chamber  22 . In short, the arrangement, alignment, and orientation of the geroters  38 ,  82  are not limited to the configurations illustrated in the Figures. 
   With respect to the various apertures (e.g. the intake aperture  74 , outlet aperture  78 , inlet aperture  106 , and exhaust aperture  110 ), the positioning and alignment of the apertures with respect to the geroters are illustrated and described above as examples only. The descriptions of the apertures that include references to clock positions are mere approximations of possible aperture configurations. As will be well appreciated by those of skill in the engine arts, the arrangement and alignment of the various ports, valves and passageways forming the fuel mixture flow path of substantially any internal combustion engine is largely a function of the intended use and operating characteristics of the engine. As such, significantly different variations of the aperture arrangements presented above are possible without departing from the spirit and scope of the present invention. One characteristic of the apertures that may be subject to significant design variations is the overlap area O. Increasing or decreasing the amount of overlap, as well as shifting the period of overlap with respect to the rotation of the geroter are modifications that are both foreseeable and appropriate when designing an engine for a specific application. 
   It should also be appreciated that a variety of peripheral components can be utilized in combination with the engine  10 . For example, the fuel mixture can be supplied by a carburetor (illustrated schematically in  FIG. 1 ) that is positioned to deliver a mixture of fuel and air to the intake port  26 . An electronic fuel injection system can be provided in place of the carburetor if such an arrangement is desired. The fuel injection system can be configured for port injection, wherein the fuel injectors inject fuel into the intake port  26 , or can be configured for direct injection of fuel into the ignition chambers  102 . Fuel injectors might also be positioned to inject fuel into the intermediate manifold  34  if so desired. In addition to the fuel mixture preparation devices described above, an exhaust system can be positioned for communication with the exhaust port  30 . The exhaust system can be of substantially any design, and is generally provided to reduce engine noise and to regulate the resonance and pressure pulsations of the exhaust flow for improved engine performance. 
   Because the engine  10  is configured as a two-cycle engine, the fuel mixture can include a lubricating oil mist for engine lubrication. By mixing the lubricating oil with the charge of fuel mixture, the lubricating oil is brought into contact with the various geroter surfaces during engine operation. The lubricating oil can be mixed directly with the liquid fuel, or can be injected into the fuel mixture from a separate oil reservoir. Various lubrication passageways and channels can also be provided as an alternative to, or in combination with, the lubricating oil/fuel mixture. For example, a circumferential groove can be provided around the outer surfaces of the outer gears  42 ,  86  to lubricate the interface between the outer gears  42 ,  86  and the geroter housing  14 . Various radially, axially, and circumferentially extending apertures and passageways can be provided in the housing  14 , the inner and outer geroter gears  50 ,  90 ,  42 ,  86 , and in the drive shaft  104  to deliver lubricating oil to various areas of the engine as required. Other lubrication methods and techniques are possible as well. 
   Various features of the invention are set forth in the following claims.