Abstract:
An internal combustion engine includes a housing having a central connecting portion and a longitudinal axis, a pair of co-axial cylinders, a crankshaft, a yoke disposed within the central connecting position, an auxiliary shaft and at least one flywheel. Each co-axial cylinder is disposed on one of opposite ends of the longitudinal axis. Each co-axial cylinder contains a piston translating therein along the longitudinal axis. The yoke connects to each piston. The yoke includes a yoke gear perambulating around the crankshaft. The flywheel is connected to the crankshaft. The flywheel has an axial cam to controllably translate the auxiliary shaft. This internal combustion engine provides for a more compact design and without the need for pulleys and belts.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of Invention 
     This invention relates to an internal combustion engine having co-axial pistons on a central yoke. More particularly, this invention relates to reciprocating and pivoting motion produced by cam rotations from a crankshaft. 
     2. Description of Related Art 
     Reciprocating piston internal combustion engines have been known for many years. A fundamental operating requirement common to internal combustion engines of the reciprocating piston type is that the reciprocal motion of the pistons must be translated into rotary motion of a crankshaft. This has been achieved most conventionally through a connecting rod attached to each piston at one end through a wrist pin and rotatably mounted to an offset crank arm of the crankshaft at an opposite end. 
     Other arrangements for converting the reciprocal motion of the piston into rotary motion of a crankshaft have also been proposed. For example, an elongated internally toothed roller gear is attached to a piston and moved to maintain engagement of the teeth with a crankshaft drive gear to impart rotation thereto. Examples of such arrangements are shown in U.S. Pat. Nos. 1,687,744, 4,608,951 and 4,395,977. Such arrangements have heretofore not achieved wide spread commercial acceptability. 
     Opposed-cylinder internal combustion engines are also known. In such engines, dual pistons are fixed to a common yoke structure or connecting rod arrangement and the pistons are reciprocated within opposed cylinders. Reciprocal motion of the pistons is conventionally translated into rotary motion by an offset crank pin of a crankshaft. U.S. Pat. Nos. 2,172,670 and 2,122,676 disclose engine designs wherein opposed pistons are connected by a connecting rod arrangement. U.S. Pat. No. 4,485,768 discloses a common yoke type internal combustion engine as described and further includes means for altering the stroke and compression ratio of the engine. Specifically, this is achieved by altering the orbital path of a co-axial crank pin and slider relative to a crankshaft axis. 
     U.S. Pat. No. 4,864,976 which discloses a dual headed piston body formed by a pair of first and second piston heads attached respectively to opposite ends of a central yoke structure. An internally toothed roller gear is mounted for rectilinear movement within the yoke structure. The roller gear engages with a crankshaft drive gear, while control and actuator means are provided for effective synchronized movement of the roller gear within the yoke structure. This arrangement maintains constant engagement of the crankshaft drive gear with the roller gear as the dual-headed piston body reciprocates within the cylinder. 
     SUMMARY OF THE INVENTION 
     An opposed-cylinder internal combustion engine, as described herein, includes housing with cylindrical chambers on opposite ends of a central connecting portion along a longitudinal cylinder axis of the housing. A manifold piston and a co-axial valve assembly translate independently along the longitudinal cylinder axis within each of the cylindrical chambers. Within the central connection portion, a yoke housing reciprocates along the cylinder axis, while a yoke gear within the yoke housing also perambulates in a transverse direction. 
     A crankshaft having shaft teeth and shaft cams rotates in the central connecting portion. Yoke teeth on the yoke gear engage the shaft teeth on the crankshaft. The shaft cams extend radially from the outer circumference of the crankshaft. Curved actuator arms engage the shaft cams. The actuator arms pivot on pegs connected to the yoke housing and push components of the co-axial valve assembly. 
     The crankshaft is connected to at least one flywheel. Flywheel cams protrude axially from the inner rim of the flywheel facing towards the yoke housing. The flywheel cams engage one or more auxiliary shafts to operate a pump or other components in the engine. 
     In various exemplary embodiments of the devices according to this invention, a compact engine design can be realized. 
     In various exemplary embodiments, this invention provides a system of flywheel cams, crankshaft cams, rocker arms, a central yoke, co-axial valves and pistons to operate an engine having opposed cylinders. 
     In various exemplary embodiments, this invention eliminates the need for chain or belt pulleys and other devices for transferring power from the rotating crankshaft. 
     These and other features and advantages of this invention are described in, or are apparent from, the following detailed description of various exemplary embodiments of the systems and methods according to this invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Various exemplary embodiments of the methods of this invention will be described in detail with reference to the following figures, wherein: 
     FIG. 1 is an elevation view for an exemplary embodiment of an opposed-cylinder internal combustion engine according to this invention; 
     FIG. 2 is a profile view for an exemplary embodiment of an opposed-cylinder internal combustion engine according to this invention; 
     FIG. 3 is a profile view for another exemplary embodiment of an opposed-cylinder internal combustion engine according to this invention; 
     FIG. 4 is a plan view for an exemplary embodiment of a yoke housing and a crankshaft assembly according to this invention; 
     FIG. 5 is an elevation view for an exemplary embodiment of a yoke housing according to this invention; 
     FIG. 6 is an elevation view for an exemplary embodiment of a yoke gear according to this invention; 
     FIG. 7 is an elevation view for an exemplary embodiment of a piston according to this invention; 
     FIG. 8 is an elevation view for an exemplary embodiment of a co-axial valve according to this invention; 
     FIG. 9 is an elevation view for an exemplary embodiment of a yoke gear assembly with a crankshaft assembly according to this invention; and 
     FIG. 10 is an isometric view for the exemplary embodiment shown in FIG. 2 of portions of an opposed-cylinder internal combustion engine according to this invention. 
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     These principles can be depicted by the accompanying drawings. FIG. 1 illustrates generally an opposed-cylinder engine  100 , in elevation view, having an opposed-cylinder dual-headed engine housing  110  of the present invention. The engine housing  110  is flanked by a left cylinder  111  with a left cap  112  and by a right cylinder  113  with a right cap  114 . The cylinders  111  and  113  commonly share a longitudinal cylinder axis  115 . The engine housing  110  also includes a pump  116  and an oil reservoir  118 . Within the engine housing  110  are housing cavities  120  along the cylinder axis  115 . A cylinder bore  121  bounds a region along the cylinder axis  115  for the cylinders  111  and  113 . 
     In the configuration shown in FIG. 1, an expansion cavity  122  is positioned for the left cylinder  111  and a compression cavity  124  is correspondingly provided for the right cylinder  113 . The housing cavities  120  also include an intake channel  126  and an exhaust channel  128 . The engine housing  110  also includes accoutrements  130  such as sparkplugs  132 , yoke attach bolts  133  (shown in FIG.  4 ), circumferential bolts  134 , axial bolts  135 , exhaust ports  136 , and an intake manifold  138 . 
     The engine  100  further includes a yoke assembly  140  in the central connecting portion, a crankshaft assembly  150 , a pair of pistons  160 , and a pair of valve assemblies  170 . Cooperation between these components is provided through four rocker pegs  180  on which eight rocker arms  190  pivot. A flywheel assembly  200  cooperates with the crankshaft assembly  150  to controllably engage auxiliary shafts of the auxiliary shaft set  220 , enabling other systems associated with the engine  100  to operate concurrently with the turning of the crankshaft assembly  150 . 
     FIG. 2 shows a profile view of an exemplary embodiment, e.g., a single-flywheel embodiment, for this invention. The crankshaft assembly  150  includes a crankshaft  152  having shaft teeth  154 , a reverse radial cam  156  and an obverse radial cam  158 . The crankshaft  152  rotates about to a crankshaft axis  155 . The crankshaft axis  155  is disposed perpendicular to the cylinder axis  115  of the housing  110 . The shaft teeth  154  outwardly circumscribe the crankshaft  152  along a portion of its length. The flywheel assembly  200  includes a flywheel  202  attached to the crankshaft  152 . FIG. 10 shows an isometric view of this exemplary embodiment. 
     The flywheel  202  includes an inner axial cam  204  and an outer axial cam  206 , both extending towards the auxiliary shaft set  220 . The axial cams  204  and  206  may extend in a continuous ring, or be arcuately segmented. The auxiliary shafts of the auxiliary shaft set  220  can be connected together by sleeve assemblies  230 . The sleeve assemblies  230  are connected to roller assemblies  240 , which in turn are connected to the yoke assembly  140 . 
     The auxiliary shaft set  220  includes an upper inner auxiliary shaft  222 , an upper outer auxiliary shaft  224 , a lower inner auxiliary shaft  226  and a lower outer auxiliary shaft  228 . In the configuration shown, the outer axial cam  206  engages the lower inner auxiliary shaft  226  (as also shown in FIG.  9 ). Additionally, the inner axial cam  204  engages the upper inner auxiliary shaft  222 . In the embodiment shown, the auxiliary shafts  222 ,  224 ,  226  and  228  are parallel to the crankshaft axis  155 . 
     The inner auxiliary shafts  222  and  226  are connected to the outer auxiliary shafts  224  and  228 , respectively, by the shaft sleeve assemblies  230 . An upper inner sleeve  232  is fixedly attached to the upper inner auxiliary shaft  222 . An upper outer sleeve  234  is fixedly attached to the upper outer auxiliary shaft  224 . The upper inner sleeve  232  and the upper outer sleeve  234  are fixedly connected together. Similarly, a lower inner sleeve  236  and a lower outer sleeve  238  are fixedly attached to respective lower auxiliary shafts  226  and  228 , and the lower sleeves  236  and  238  are fixedly connected together. 
     The inner axial cam  204  pushes the upper inner auxiliary shaft  222  away from the flywheel  202  along a direction parallel to the crankshaft axis  155 . Because the upper sleeves  232  and  234  are fixedly joined together, the motion of the upper inner auxiliary shaft  222  is accompanied by complimentary motion of the upper outer shaft  224 . This force against the upper outer auxiliary shaft  224  is partially counteracted by an upper outer spring  235  disposed between the upper outer sleeve  234  and the housing  110 . 
     Similarly, the outer axial cam  206  pushes the lower inner auxiliary shaft  226  away from the flywheel  202 , together with the lower outer shaft  228  through the lower sleeves  236  and  238 . This force applied to move against the lower outer auxiliary shaft  228  is partially counteracted by a lower outer spring  239  between the lower outer sleeve  238  and the housing  110 . 
     Through the cylinder bore  121 , the roller assemblies  240  are shown cooperating with the sleeve assemblies  230 . An upper roller  242  is connected to the upper inner sleeve  232 . The upper roller  242  moves radially and axially along an upper slider  244 . Similarly, a lower roller  246  is connected to the lower inner sleeve  236 . The lower roller  246  moves radially and axially along a lower slider  248 . As the crankshaft assembly  150  rotates, the yoke assembly  140  moves (or perambulates) about the crankshaft  152 . 
     As the upper inner auxiliary shaft  222  shifts axially along the direction of the crankshaft axis  155 , the yoke assembly  140  moves around the crankshaft  152 . This interaction is shown in FIGS. 2 and 10. Coincidentally, the upper roller  242  slides along the upper slider  244 . Consequently, the upper roller  242  moves radially inward and outward while also moving along the direction of the crankshaft axis  155 . The upper roller  242  is fixedly connected to the auxiliary shaft  222 , which shifts axially along the direction of the crankshaft axis  155  being pushed back and forth by the inner axial cam  204  of the flywheel  202 . Similarly, the lower inner auxiliary shaft  226  shifts axially along the direction of the crankshaft axis  155  as the lower roller  246  slides along lower slider  248 . 
     FIG. 3 shows a profile view of another exemplary embodiment, e.g., a dual-flywheel embodiment, for this invention. The duo-flywheel assembly  210  includes an outer flywheel  212  having an outer axial cam  214 , and an inner flywheel  216  having an inner axial cam  218 . Both outer and inner flywheels  212  and  216  are attached to the crankshaft  152 . The axial cams  214  and  218  can either extend as a continuous ring or else be arcuately segmented. 
     In the configuration shown, the inner axial cam  218  on the inner flywheel  216  pushes the upper inner auxiliary shaft  222  along the crankshaft axis  155  away from the inner flywheel  216 . This force, by the connection with the upper inner sleeve  232  to the upper outer sleeve  234 , also pushes the upper outer shaft  224 . This force against the upper outer auxiliary shaft  224  is partially counteracted by an upper inner spring  233  disposed between the upper inner sleeve  232  and the housing  110 . 
     Additionally, the outer flywheel  212  (absent the outer axial cam  214 ) engages the lower inner auxiliary shaft  226 . Any similar force against the lower inner auxiliary shaft  228  is partially counteracted by a lower inner spring  237  between the lower inner sleeve  236  and the housing  110 . Otherwise, the operation is similar to the single-flywheel embodiment described for FIG.  2 . 
     FIG. 4 illustrates a plan view of the yoke assembly  140  and the crankshaft assembly  150 . The yoke assembly includes a yoke housing  142  held to the engine housing by attach bolts  135 . FIG. 5 provides an elevation view of the yoke housing  142  including four bolt holes  143  through which the attach bolts  135  are inserted, a yoke gear cavity  144 , and male screw threads  145  for attaching the piston  160 . The yoke gear  146  includes yoke teeth  148  inwardly circumscribing the path to engage the shaft teeth  154  of the crankshaft assembly  150 . A variety of closed geometric shapes having a continuous derivative can form the interior path. 
     FIG. 6 shows an elevation view of a yoke gear  146  having an elongated oval having a semicircle at either end. The yoke teeth  148  engage the shaft teeth  154  (as shown in FIG. 9) to move the yoke gear  146  around the crankshaft  152 . The motion of the yoke gear  146  includes translating along two orthogonal directions. The direction having a greater extent of motion translates the yoke gear  146  longitudinally along the cylinder axis  115 . The direction having a lesser extent of motion translates the yoke gear  146  transversely either towards the auxiliary shafts  222  and  224  or else towards the lower auxiliary shafts  226  and  228 . The yoke housing  142  converts the perambulatory motion of the yoke gear  146  within the yoke cavity  144  into reciprocating translation along the cylinder axis  115  towards either the left cylinder  111  or else the right cylinder  113 . 
     FIG. 7 shows an elevation view of the piston  160  with several chambers and surfaces. The piston  160  includes a valve cavity  162  terminating in valve seats  163 . The piston  160  also includes o-ring cavities  164  for sealing regions separated by walls of the cylinder bore  121 . The piston  160  connects to the male screw threads  145  of the yoke housing  142  by female screw threads  165 , so that when the yoke assembly  140  translates along the cylinder axis  115 , the pistons  160  follow in concert. The piston  160  also includes an intake chamber  166  and an exhaust chamber  168 . 
     FIG. 8 shows an elevation view of part of the co-axial valve assembly  170  operating within the cylinder cavity  162 . The co-axial valve assembly  170  includes an inner valve head  171  connected to an inner valve stem  172 , and an outer valve head  173  connected to an outer valve stem  174 . Additionally, as shown in FIG. 9, inner valve stem  172  is restrained by an inner spring  175  against an inner stop, and outer valve stem  174  is restrained by an outer spring  176  against an outer stop, both stops connected to a spring cup  177 . 
     The elevation view of the yoke assembly  140  and the crankshaft assembly  150  in FIG. 9 also illustrates the rocker pivots or pegs  180  and the rocker arms  190  from FIG. 1 in greater detail. The rocker pegs  180  include the upper left peg  182 , the lower left peg  184 , the upper right peg  186  and the lower right peg  188 . The positions of these rocker pegs  180  correspond to the bolt holes  143  of the yoke housing  142 . The axes of the rocker pegs  180  are parallel to the crankshaft axis  155 . 
     The rocker arms  190  for the left cylinder  111  include the upper left valve arm  191 , the upper left cam arm  192 , the lower left valve arm  193 , the lower left cam arm  194 . The upper left arms  191  and  192  rotate on the upper left peg  182 . The lower left arms  193  and  194  rotate on the lower left peg  184 . The rocker arms  190  for the right cylinder  113  include the upper right valve arm  195 , the upper right cam arm  196 , the lower right valve arm  197 , the lower right cam arm  198 . The upper right arms  195  and  196  rotate on the upper right peg  186 . The lower right arms  197  and  198  rotate on the lower right peg  188 . 
     As the shaft assembly  150  turns, the obverse radial cam  158  pushes the upper left cam arm  192  to turn clockwise around upper left peg  182 . The motion of the upper left cam arm  192  turns upper left valve arm  191  clockwise to push the inner valve stem  172  leftwards. Concurrently, the reverse radial cam  156  pushes the lower left cam arm  194  counterclockwise around lower left peg  184 . The motion of the lower left cam arm  194  turns lower left valve arm  193  counterclockwise to push the spring cup  177  leftwards. 
     Also while the shaft assembly  150  turns, the reverse radial cam  156  pushes the lower left cam arm  194  to turn counterclockwise around lower left peg  184 . The motion of lower left cam arm  194  turns lower left valve arm  193  counterclockwise to push the inner valve stem  172  leftwards. As the spring cup  177  is pushed, the springs  175  and  176  are compressed, moving the valve stems  172  and  174  leftward. This motion pushes the inner and outer valves  171  and  173  towards their closed positions. 
     The shaft assembly  150  simultaneously translates the yoke housing  142 , so that the translation of the piston  160  cooperates with the translation of the inner and outer valve heads  171  and  173 , while the left cylinder  111  provides an expansion cavity  122 . These positions are reversed as the yoke assembly  140  shifts leftward so that the radial cams  156  and  158  engage the right cam arms  196  and  198  and thereby operate in conjunction with the right valve arms  195  and  197 . 
     Similarly, FIG. 9 shows the upper right valve arm  195  and the upper right cam arm  196  in rest positions, while the right cylinder  113  provides a compression cavity  124 . The lower right valve arm  197  presses against the spring cup  177  for the right cylinder  113 , and limits the clockwise rotation of the lower right cam arm  198 . FIG. 10 shows the interaction of the lower left cam arm  194  rotating counterclockwise around the lower left peg  184  by the reverse radial cam  156 . The lower left valve arm  193 , moving in conjunction with the lower left cam  194 , pushes against the inner valve stem  172  through a linkage, not shown. 
     In particular, FIG. 10 shows an isometric view of selected interacting components in the opposed-cylinder engine  100 . The assemblies shown include the housing  110 , the valve assembly  170  and the flywheel assembly  200 . The components shown include the cylinder bore  121 , the yoke gear  146  with yoke teeth  148 , the crankshaft  152 , shaft teeth  154 , crankshaft axis  155 , reverse radial cam  156 . The valve assembly  170  includes valve heads  171  and  173 , valve stems  173  and  174 . 
     The flywheel assembly  200  includes the flywheel  202  and the inner axial cam  204 . Additional components shown include the lower left peg  184 , the lower left valve arm  193  and the lower left cam arm  194 , the inner auxiliary shafts  222  and  226 , and their sleeves  232  and  236 . The interactions of these components are explained above. 
     By providing an arrangement of flywheel cams, crankshaft cams, auxiliary shafts and pivoting arms, a more compact engine design can be realized. Further, such a design further eliminates the need for endless belt to connect pulleys and other devices for transferring power from the rotating crankshaft. The use of cams and rocker arms provide a more robust means of transmitting torque to auxiliary components of an engine than generally available through chains or belts. 
     While this invention has been described in conjunction with exemplary embodiments outlined above, many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention, as set forth above, are intended to be illustrative, not limiting. Various changes can be made without departing from the spirit and scope of the invention.