Abstract:
An engine having axial inline pistons connected to side power output shafts is disclosed. The engine includes a cylinder defining an interior space of the cylinder; a first piston that reciprocates in the interior space of the cylinder wherein the first piston has a first end forming a first piston head; a first piston rod attached to the first piston at a second end of the first piston opposite the first end of the first piston; a second piston that reciprocates in the interior space of the cylinder, wherein the second piston has a first end forming a second piston head; a second piston rod attached to the second piston at a second end of the second piston opposite the first end of the second piston; a first connecting rod connected to the first piston rod and coupled to a first power output shaft; and a second connecting rod connected to the second piston rod and coupled to the first power output shaft. The first piston head and the second piston head define a combustion chamber in the cylinder between the first piston head and the second piston head, and the first piston head and the second piston head move away from each other on a first power stroke of the first piston and a second power stroke of the second piston.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims priority from U.S. Provisional Patent Application No. 61/250,439 filed Oct. 9, 2009. 
     
    
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH 
       [0002]    Not Applicable. 
       BACKGROUND OF THE INVENTION 
       [0003]    1. Field of the Invention 
         [0004]    This invention relates to an engine having axial combustion chambers and axial pistons connected to side power output shafts. 
         [0005]    2. Description of the Related Art 
         [0006]    Various engine designs are known. For example, U.S. Pat. No. 6,769,384 discloses a radial piston engine wherein power is transferred such that the power take-off is truly balanced in that the piston runs truly parallel to the cylinder walls. This radial engine reduces wear of the cylinders and piston rings, provides improved gas mileage due to the reduced piston drag, and produces greater torque than other engine designs. Other engine designs are shown in U.S. Pat. Nos. 3,319,416 and 1,419,693. 
         [0007]    U.S. Patent Application Publication No. 2008/0149052 shows and describes an engine having axially opposed cylinders. 
         [0008]    However, there is still a need for further improvements in an inline piston engine: (i) where power take-off is truly balanced such that the piston runs truly parallel to the cylinder walls, (ii) that provides improved gas mileage by reducing piston drag, and (iii) that produces greater torque. 
       SUMMARY OF THE INVENTION 
       [0009]    The foregoing needs are met by an engine according to the present invention. The engine includes a cylinder defining an interior space of the cylinder; a first piston that reciprocates in the interior space of the cylinder wherein the first piston has a first end forming a first piston head; a first piston rod attached to the first piston at a second end of the first piston opposite the first end of the first piston; a second piston that reciprocates in the interior space of the cylinder, wherein the second piston has a first end forming a second piston head; a second piston rod attached to the second piston at a second end of the second piston opposite the first end of the second piston; a first connecting rod connected to the first piston rod and coupled to a first power output shaft; and a second connecting rod connected to the second piston rod and coupled to the first power output shaft. The first piston head and the second piston head define a combustion chamber in the cylinder between the first piston head and the second piston head, and the first piston head and the second piston head move away from each other on a first power stroke of the first piston and a second power stroke of the second piston. 
         [0010]    The first piston rod can be attached to the first piston such that the first piston rod extends diametrically across the second end of the first piston, and the second piston rod can be attached to the second piston such that the second piston rod extends diametrically across the second end of the second piston. A fuel intake port can be in fluid communication with the interior space of the cylinder, and an exhaust port can be in fluid communication with the interior space of the cylinder, wherein the fuel intake port and the exhaust port are located in opposite ends of the cylinder. 
         [0011]    In one version of the engine, a third connecting rod is connected to the first piston rod and coupled to a second power output shaft, and a fourth connecting rod is connected to the second piston rod and coupled to the second power output shaft. In another version of the engine, the engine includes a third piston having a third end forming a third piston head wherein the first piston rod is attached to the third piston at a second end of the third piston opposite the first end of the third piston; and the engine includes a fourth piston having a fourth end forming a fourth piston head wherein the second piston rod is attached to the fourth piston at a second end of the fourth piston opposite the first end of the fourth piston. 
         [0012]    In another version of the engine, the engine includes a first cylinder head at a first end of the cylinder; and a second cylinder head at a second end of the cylinder. The third piston moves toward the first cylinder head during the first power stroke of the first piston, and the fourth piston moves toward the second cylinder head during the second power stroke of the second piston. The engine can include a housing, a first end plate sealing a first open end of the housing, and a second end plate sealing a second open end of the housing. A section of the first end plate forms the first cylinder head, and a section of the second end plate forms the second cylinder head. The housing can comprise a pair of housing sections, and the pair of housing sections can be connected by a bearing wherein the first power output shaft rotates in the bearing. 
         [0013]    The engine can include a cylinder block that divides the combustion chamber in the cylinder into a first combustion chamber volume adjacent the first piston head and a second combustion chamber volume adjacent the second piston head. The cylinder block can include a first fuel intake port for providing a fuel to the first combustion chamber volume and a second fuel intake port for providing the fuel to the second combustion chamber volume. 
         [0014]    The third piston head can define a second combustion chamber in the cylinder between the third piston head and the first cylinder head, and the first cylinder head can include a third fuel intake port for providing a fuel to the second combustion chamber. The fourth piston head can define a third combustion chamber in the cylinder between the fourth piston head and the second cylinder head, and the second cylinder head can include a fourth fuel intake port for providing a fuel to the third combustion chamber. 
         [0015]    The cylinder block can include a spark device for igniting fuel in the first combustion chamber volume and the second combustion chamber volume. The first cylinder head can include a spark device for igniting fuel in the second combustion chamber. The second cylinder head can include a spark device for igniting fuel in the third combustion chamber. 
         [0016]    The engine can include a first air compression chamber, a first compression plate slidingly arranged in the first air compression chamber and in sealing contact with an inner surface of the first air compression chamber, and a first compression rod connected to the first piston rod and the first compression plate. The first compression plate compresses air in the first air compression chamber upon movement of the first piston rod. The engine can include a first fluid pump chamber, a first pump plate slidingly arranged in the first fluid pump chamber and in sealing contact with an inner surface of the first fluid pump chamber, and a first pump rod connected to the second piston rod and the first pump plate. The first pump plate pumps fluid from the first fluid pump chamber upon movement of the second piston rod. The housing can have a first channel in fluid communication with the first air compression chamber for transporting air from the first air compression chamber, and also a second channel in fluid communication with the first fluid pump chamber for transporting fluid from the first fluid pump chamber. 
         [0017]    The engine can include a drive gear connected to the first power output shaft. The engine can further include a drive element selected from chains and belts, wherein the drive element is coupled to the drive gear. 
         [0018]    In the engine, the first connecting rod can be coupled to a second power output shaft, and a second connecting rod can be coupled to the second power output shaft. The first power output shaft and the second power output shaft can be coaxial. The first connecting rod can be linked to a first set of cams, the second connecting rod can be linked to each of the first set of cams, the second connecting rod can be linked to a second set of cams, and one cam of the second set of cams can be connected to the first power output shaft, and another cam of the second set of cams can be connected to the second power output shaft. The second connecting rod can include a pair of spaced apart arms such that the first connecting rod and the first set of cams can move between the pair of spaced apart arms. 
         [0019]    It is therefore an advantage of the present invention to provide an engine that dramatically reduces cylinder friction and wear thereby improving gas mileage and lowering emissions. 
         [0020]    It is another advantage of the present invention to provide an engine that has increased torque. 
         [0021]    It is still another advantage of the present invention to provide an engine that allows for a low mass piston, which provides for higher speeds and greater horsepower. 
         [0022]    It is yet another advantage of the present invention to provide an engine that can be used for standard internal combustion engines, diesel and 2 cycle designs. It can also be used as a pump if the power is reversed. 
         [0023]    It is still another advantage of the present invention to provide an engine that requires a smaller block and can be mounted sideways. 
         [0024]    It is yet another advantage of the present invention to provide an engine that is suitable for off road vehicles such as ATVs and military equipment. 
         [0025]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has the upper pistons and lower pistons connected to the same two power output shafts. 
         [0026]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has the two middle pistons forming a single combustion chamber. 
         [0027]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has one or more of the shafts coming out of the cylinder that connect to a push rod and plates that compress air in the resulting chambers. These chambers compress air in both an up and down motion. 
         [0028]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has one or more of the shafts coming out of the cylinder that connect to a push rod that pumps oil in a resulting chamber. 
         [0029]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has two power output shafts located between the upper pistons and lower pistons, either directly below the cylinder, or off to the side. 
         [0030]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has a housing that is extruded, enabled by the design of the pistons and cranks. This housing by design also has channels for water and oil flow either extruded in the housing or molded, cast or added to the inside or outside of the housing. 
         [0031]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has a design that allows for either a two cycle or four cycle engine by adding valves to the piston push rods or chains or belts to the power output shafts. The chains, belts and push rods can be split between both power output shafts or connected just to one power output shaft. 
         [0032]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has four push rods that are connected directly to a flange designed onto the upper pistons and lower pistons or to a shaft that extends through both sides of the upper pistons and lower pistons. 
         [0033]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has a top plate housing, a bottom plate housing, and a middle housing. 
         [0034]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has bearings for power output shafts wherein the bearings are housed between two engine housing halves that connect both engine housing halves. 
         [0035]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has four push rods where two of the push rods are Y-shaped or U-shaped to allow for a symmetric distribution of power from the upper pistons and lower pistons. 
         [0036]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that has valves that are either rocker arm type valves, slide valves or rotary type valves (Coates valves). 
         [0037]    It is yet another advantage of the present invention to provide an engine, pump, compressor or the like that has a fuel injector and a spark plug in the top plate housing, the bottom plate housing, and the middle cylinder block respectively, or aspiration with gas or diesel fuel. 
         [0038]    It is still another advantage of the present invention to provide an engine, pump, compressor or the like that is connected to a second four cylinders that are at 90° or 180° out of phase and connect to the two power output shafts of the first engine half allowing for increased power and a smother running engine. 
         [0039]    These and other features, aspects, and advantages of the present invention will become better understood upon consideration of the following detailed description, drawings, and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0040]      FIG. 1  is a perspective view of a first embodiment of an engine according to the invention. 
           [0041]      FIG. 2  is a front view of the engine of  FIG. 1 . 
           [0042]      FIG. 3  is a cross-sectional view taken along line  3 - 3  of  FIG. 2 . 
           [0043]      FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 2 . 
           [0044]      FIG. 5  is a cross-sectional view taken along line  5 - 5  of  FIG. 3 . 
           [0045]      FIG. 6  is a right front perspective detailed view taken along line  6 - 6  of  FIG. 5  showing the linkage between the connecting rods and the power output shafts on one side of the engine of  FIGS. 1-6 . 
           [0046]      FIG. 7  is a front view of a second embodiment of an engine according to the invention. 
           [0047]      FIG. 8  is side view of the engine of  FIG. 7 . 
           [0048]      FIG. 9  is a cross-sectional view taken along line  9 - 9  of  FIG. 8 . 
       
    
    
       [0049]    Like reference numerals are used to depict like parts from Figure to Figure throughout the drawings. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0050]    The present invention is directed to a piston engine wherein the power take-off is truly balanced and the piston runs truly parallel to the cylinder walls. Looking at  FIGS. 1-6 , a first example embodiment of an engine  10  includes a first top outer housing section  12  and a second bottom outer housing section  13  which may be extruded in the hollow generally rectangular shape shown in  FIGS. 1-6 . The housing section  12  and the housing section  13  are mated to form an internal cylinder  15  that extends from a top end to a bottom end of the engine  10 . The cylinder  15  defines a cylindrical interior space  16 . It should be understood that the terms “bottom”, “top”, “left” and “right” are used for ease and clarity of description, and in no way do these terms limit the orientation of the engine  10  in operation. 
         [0051]    An open end of the top housing section  12  is closed off by a first end plate  18  that forms a first cylinder head  19  for the cylinder  15 . A combustion chamber  20  is defined below the first cylinder head  19  for the cylinder  15 . A fuel intake port  21  with a fuel injector  22  and a spark plug  23  are arranged in the first cylinder head  19 . Optionally, a carburetor can be associated with the fuel intake port  21 , or the spark plug can be omitted. Each fuel injector or carburetor is positioned for directing fuel and/or intake air in its associated intake port. The operation of internal combustion engines is well known and will not be explained further. 
         [0052]    An open end of the bottom housing section  13  is closed off by a second end plate  25  that forms a second cylinder head  26  for the cylinder  15 . A combustion chamber  27  is defined above the second cylinder head  26  for the cylinder  15 . A fuel intake port  28  with a fuel injector  29  and a spark plug  30  are arranged in the second cylinder head  26  for the cylinder  15 . Optionally, a carburetor can be associated with the fuel intake port  28 , or the spark plug can be omitted. The top housing section  12 , the bottom housing section  13 , the first end plate  18 , and the second end plate  25  can be formed from, for example, an aluminum alloy, a steel alloy, or a composite material. 
         [0053]    The engine  10  includes a first piston  33  slidingly arranged in the interior space  16  of the cylinder  15 . The first piston  33  is in sealing contact with an inner surface of the cylinder  15 . The first piston  33  reciprocates in the interior space  16  of the cylinder  15 . The first piston  33  includes a first piston head  34 . At the end of the first piston  33  opposite the first piston head  34 , one or more flanges of the first piston  33  are connected to a first piston rod  36  which extends diametrically across the end of the first piston  33 . 
         [0054]    The engine  10  includes a second piston  39  slidingly arranged in the interior space  16  of the cylinder  15 . The second piston  39  is in sealing contact with an inner surface of the cylinder  15 . The second piston  39  reciprocates in the interior space  16  of the cylinder  15 . The second piston  39  includes a second piston head  40 . At the end of the second piston  39  opposite the second piston head  40 , one or more flanges of the second piston  39  are connected to a second piston rod  42  which extends diametrically across the end of the second piston  39 . 
         [0055]    The engine  10  includes a third piston  44  slidingly arranged in the interior space  16  of the cylinder  15 . The third piston  44  is in sealing contact with an inner surface of the cylinder  15 . The third piston  44  reciprocates in the interior space  16  of the cylinder  15 . The third piston  44  includes a third piston head  45 . At the end of the third piston  44  opposite the third piston head  45 , one or more flanges of the third piston  44  are connected to the first piston rod  36  which extends diametrically across the end of the third piston  44 . 
         [0056]    The engine  10  includes a fourth piston  47  slidingly arranged in the interior space  16  of the cylinder  15 . The fourth piston  47  is in sealing contact with an inner surface of the cylinder  15 . The fourth piston  47  reciprocates in the interior space  16  of the cylinder  15 . The fourth piston  47  includes a fourth piston head  48 . At the end of the fourth piston  47  opposite the fourth piston head  48 , one or more flanges of the fourth piston  47  are connected to the second piston rod  42  which extends diametrically across the end of the fourth piston  47 . 
         [0057]    Each of the pistons  33 ,  39 ,  44 ,  47  can have a pair of O-rings on its outer surface. A first of the pair of O-rings for each of the pistons  33 ,  39 ,  44 ,  47  is an oil wiping ring located at the end of each of the pistons  33 ,  39 ,  44 ,  47  that connects to the adjacent piston. This O-ring seals oil from the inside of the associated combustion chamber. A second of the pair of O-rings for each of the pistons  33 ,  39 ,  44 ,  47  is located about ⅔ to ¾ of the way to the end of each of the pistons  33 ,  39 ,  44 ,  47  near the associated combustion chamber. This O-ring seals off the combustion chamber. 
         [0058]    The engine  10  includes a cylinder block  50  that defines a first combustion chamber volume  51  between the cylinder block  50  and the first piston head  34 , and that defines a second combustion chamber volume  52  between the cylinder block  50  and the second piston head  40 . A first fuel intake port  53 , a second fuel intake port  54 , a fuel injector  55 , and a spark plug  56  are provided in the cylinder block  50 . The first fuel intake port  53  can provide fuel from the fuel injector  55  to the first combustion chamber volume  51 . The second fuel intake port  54  can provide fuel from the fuel injector  55  to the second combustion chamber volume  52 . The spark plug  56  can ignite fuel in the first combustion chamber volume  51  and the second combustion chamber volume  52 . 
         [0059]    The engine  10  includes a first connecting rod  58  that is attached by a pin to the first piston rod  36 , a second connecting rod  59  that is attached by a pin to the second piston rod  42 , a third connecting rod  60  that is attached by a pin to the first piston rod  36 . and a fourth connecting rod  61  that is attached by a pin to the second piston rod  42 . Referring to  FIGS. 4 and 6 , the first connecting rod  58  is connected to a first set of cams  64   a ,  64   b  and the second connecting rod  59  is connected by spaced apart arms  63  to a second set of cams  65   a ,  65   b . Cam  65   a  is connected to a first power output shaft  67 , and cam  65   b  is connected to a second power output shaft  68 . A third power output shaft  69  and a fourth power output shaft (not shown) are connected to the third connecting rod  60  and the fourth connecting rod  61  in the same manner as the connections between the first connecting rod  58 , the second connecting rod  59 , the first power output shaft  67 , and the second power output shaft  68 . A bearing plate  70   a  connects both the top housing section  12  and the bottom housing section  13 , and also acts as bearing surface for the first output shaft  67 . Likewise, a bearing plate  70   b  connects both the top housing section  12  and the bottom housing section  13 , and also acts as bearing surface for the second power output shaft  68 . Similar bearing plates are provided for the third power output shaft  69  and the fourth power output shaft. 
         [0060]    A first drive gear  71  is connected to the first power output shaft  67 , and a second drive gear  72  is connected to the third power output shaft  69  as shown in  FIG. 1 . A chain  73  can transmit motion from the first drive gear  71  (see  FIG. 2 ). Similar drive gears and chains can be provided on the second power output shaft  68  and the fourth power output shaft. 
         [0061]    The engine  10  includes a first air compression chamber  75  adjacent the first end plate  18 . A first compression plate  77  is slidingly arranged in the first air compression chamber  75 , and the first compression plate  77  is in sealing contact with an inner surface of the first air compression chamber  75 . A first compression rod  78  is connected to the first compression plate  77 . The first compression rod  78  is also connected to the first piston rod  36  by a pin  79 . The first compression plate  77  compresses air in the first air compression chamber  75 . The air is compressed in both an up and down motion. A channel  80  is in fluid communication with the first air compression chamber  75  for transporting air from the first air compression chamber  75 . The channel can be extruded in the top housing section  12  and/or the bottom housing section  13 , or molded, cast or added to the top housing section  12  and/or the bottom housing section  13 . 
         [0062]    The engine  10  includes a second air compression chamber  81  adjacent the first end plate  18 . A second compression plate  82  is slidingly arranged in the second air compression chamber  81 , and the second compression plate  82  is in sealing contact with an inner surface of the second air compression chamber  81 . A second compression rod  83  is connected to the second compression plate  82 . The second compression rod  83  is also connected to the first piston rod  36  by a pin  84 . The second compression plate  82  compresses air in the second air compression chamber  81 . The air is compressed in both an up and down motion. A channel is in fluid communication with the second air compression chamber  81  for transporting air from the second air compression chamber  81 . The channel can be extruded in the top housing section  12  and/or the bottom housing section  13 , or molded, cast or added to the top housing section  12  and/or the bottom housing section  13 . 
         [0063]    The engine  10  includes a first fluid pump chamber  86  adjacent the second end plate  25 . A first pump plate  87  is slidingly arranged in the first fluid pump chamber  86 , and the first pump plate  87  is in sealing contact with an inner surface of the first fluid pump chamber  86 . A first pump rod  88  is connected to the first pump plate  87 . The first pump rod  88  is also connected to the second piston rod  42  by a pin  89 . The first pump plate  87  pumps fluid from the first fluid pump chamber  86  upon movement of the second piston rod  42 . A channel is in fluid communication with the first fluid pump chamber  86  for transporting air from the first fluid pump chamber  86 . The channel can be extruded in the top housing section  12  and/or the bottom housing section  13 , or molded, cast or added to the top housing section  12  and/or the bottom housing section  13 . 
         [0064]    The engine  10  includes a second fluid pump chamber  91  adjacent the second end plate  25 . A second pump plate  93  is slidingly arranged in the second fluid pump chamber  91 , and the second pump plate  93  is in sealing contact with an inner surface of the second fluid pump chamber  91 . A second pump rod  94  is connected to the second pump plate  93 . The second pump rod  94  is also connected to the second piston rod  42  by a pin  95 . The second pump plate  93  pumps fluid from the second fluid pump chamber  91  upon movement of the second piston rod  42 . A channel  96  is in fluid communication with the second fluid pump chamber  91  for transporting air from the second fluid pump chamber  91 . The channel can be extruded in the top housing section  12  and/or the bottom housing section  13 , or molded, cast or added to the top housing section  12  and/or the bottom housing section  13 . 
         [0065]    In  FIG. 5 , the first piston  33  and the third piston  44  (which are connected to the first piston rod  36 ) are shown near bottom of their stroke, and the second piston  39  and the fourth piston  47  (which are connected to the second piston rod  42 ) are shown near top of their stroke. At the time in the engine cycle shown in  FIG. 5 , the spark plug  56  will fire, fuel and air in the first combustion chamber volume  51  and the second combustion chamber volume  52  has been compressed, and when the spark plug  56  fires, the fuel-air mixtures ignite. The resulting explosions drive the second piston  39  and the fourth piston  47  downward and the first piston  33  and the third piston  44  upward. 
         [0066]    When the first piston  33  and the third piston  44  are near top of their motion, and the second piston  39  and the fourth piston  47  are near bottom of their motion, the spark plugs  23 , 30  will fire, fuel and air in the combustion chambers  20 ,  27  has been compressed, and when the spark plugs  23 , 30  fire, the fuel-air mixtures ignite. The resulting explosion drives the first piston  33  and the third piston  44  downward and the second piston  39  and the fourth piston  47  upward. 
         [0067]    As the first piston  33  and the third piston  44  reciprocate, the first piston rod  36  rotates the first set of cams  64   a ,  64   b,  the first piston rod  36  translates the first compression rod  78  such that the first compression plate  77  compresses air in the first air compression chamber  75 , and the first piston rod  36  translates the second compression rod  83  such that the second compression plate  82  compresses air in the second air compression chamber  81 . As the first piston  33  and the third piston  44  reciprocate, the first piston rod  36  rotates a set of cams (similar to the first set of cams  64   a ,  64   b ) on the opposite side of the cylinder. Rotation of the first set of cams  64   a ,  64   b  provides rotation to the first power output shaft  67  and second power output shaft  68 , and rotation of the similar set of cams on the opposite side of the cylinder  15  provides rotation to the third power output shaft  69  and the fourth power output shaft. 
         [0068]    As the second piston  39  and the fourth piston  47  reciprocate, the second piston rod  42  rotates the second set of cams  65   a ,  65   b  (and the similar set of cams on the opposite side of the cylinder  15 ), the second piston rod  42  translates the first pump rod  88  such that the first pump plate  87  pumps fluid from the first fluid pump chamber  86 , and the second piston rod  42  translates the second pump rod  94  such that the second pump plate  93  pumps fluid from the second fluid pump chamber  91 . Rotation of the second set of cams  65   a ,  65   b  provides rotation to the first power output shaft  67  and second power output shaft  68 . Rotation of a set of cams (similar to the second set of cams  65   a ,  65   b ) provides rotation to the third power output shaft  69  and fourth power output shaft. 
         [0069]    Looking at  FIGS. 7-9 , a second example embodiment of an engine  110  is shown. The engine  110  includes a first outer housing section  112  and a second outer housing section  113  which may be extruded in the hollow generally rectangular shape shown in  FIGS. 7-9 . The housing section  112  and the housing section  113  can be formed from, for example, an aluminum alloy, a steel alloy, or a composite material. The housing section  112  and the housing section  113  are mated to form an internal cylinder  115  that extends from a top end to a bottom end of the engine  110 . The cylinder  115  defines a cylindrical combustion chamber  116 . An open end of the housing sections  112 ,  113  is closed off by a first end plate  118 . An opposite open end of the housing sections  112 , 113  is closed off by a second end plate  125 . It should be understood that the terms “bottom”, “top”, “left” and “right” are used for ease and clarity of description, and in no way do these terms limit the orientation of the engine  110  in operation. 
         [0070]    The engine  110  includes a first piston  133  slidingly arranged in the combustion chamber  116  of the cylinder  115 . The first piston  133  is in sealing contact with an inner surface of the cylinder  115 . The first piston  133  reciprocates in the combustion chamber  116  of the cylinder  115 . The first piston  133  includes a first piston head  134 . At the end of the first piston  133  opposite the first piston head  134 , one or more flanges of the first piston  133  are connected to a first piston rod  136  which extends diametrically across the end of the first piston  133 . 
         [0071]    The engine  110  includes a second piston  139  slidingly arranged in the combustion chamber  116  of the cylinder  115 . The second piston  139  is in sealing contact with an inner surface of the cylinder  115 . The second piston  139  reciprocates in the combustion chamber  116  of the cylinder  115 . The second piston  139  includes a second piston head  140 . At the end of the second piston  139  opposite the second piston head  140 , one or more flanges of the second piston  139  are connected to a second piston rod  142  which extends diametrically across the end of the second piston  139 . 
         [0072]    Each of the pistons  133 ,  139  can have one or more O-rings on its outer surface. Oil ring slots and associated O-rings  149   a ,  149   b  are provided in the cylinder to seal oil from the inside of the combustion chamber  116 . 
         [0073]    Fuel intake ports  153 ,  154  and a spark plug  156  are provided in the cylinder  115 . The fuel intake ports  153 ,  154  can provide fuel to the combustion chamber  116 . The spark plug  156  can ignite fuel in the combustion chamber  116 . The engine  110  further includes a first exhaust pipe  146  in fluid communication with an exhaust port  147  in the cylinder  115 , and a second exhaust pipe  148  in fluid communication with another exhaust port (not shown) in the cylinder  115 . The fuel intake ports  153 ,  154  and exhaust ports  147  are at opposite ends of the cylinder  115 . 
         [0074]    The engine  110  includes a first connecting rod  158  that is attached by a pin to the first piston rod  136 , a second connecting rod  159  that is attached by a pin to the second piston rod  142 , a third connecting rod  160  that is attached by a pin to the first piston rod  136 . and a fourth connecting rod  161  that is attached by a pin to the second piston rod  142 . Referring to  FIG. 9 , the first connecting rod  158  and the second connecting rod  159  are connected to a first set of cams  164 . The third connecting rod  160  and the fourth connecting rod  161  are connected to a second set of cams  165 . Cams  164  are connected to a first power output shaft  167  and a second power output shaft  168 . Cams  165  are connected to third power output shaft  169  and a fourth power output shaft (not shown). 
         [0075]    The first connecting rod  158 , the second connecting rod  159  and the first set of cams  164  of the engine  110  can be constructed and assembled in the manner shown in  FIG. 6  for engine  10 . Likewise, the third connecting rod  160 , the fourth connecting rod  161 , and the second set of cams  165  of the engine  110  can be constructed and assembled in the manner shown in  FIG. 6  for engine  10 . 
         [0076]    A first drive gear  171  is connected to the first power output shaft  167 , a second drive gear  172  is connected to the second power output shaft  168 , and a third drive gear  173  is connected to the third power output shaft  169  as shown in  FIGS. 7-8 . A chain can transmit motion from any of the drive gears as in the embodiment of  FIG. 2 . A similar drive gear and chain can be provided on the fourth power output shaft. 
         [0077]    In  FIG. 9 , the first piston  133 , which is connected to the first piston rod  136 , is shown near the top of its stroke, and the second piston  139 , which is connected to the second piston rod  142 , is shown near the bottom of its stroke. When the first piston  133  is near bottom of its motion, and the second piston  139  is near top of its motion, the spark plug will fire, fuel and air in the combustion chamber  116  has been compressed, and when the spark plug fires, the fuel-air mixture ignites. The resulting explosion drives the first piston  133  upward and the second piston  139  downward back to the positions shown in  FIG. 9 . 
         [0078]    As the first piston  133  reciprocates, the first piston rod  136  rotates the first set of cams  164  and the second set of cams  165 . As the second piston  139  reciprocates, the second piston rod  142  also rotates the first set of cams  164  and the second set of cams  165 . Rotation of the first set of cams  164  provides rotation to the first power output shaft  167  and second power output shaft  168 . Rotation of the second set of cams  165  provides rotation to the third power output shaft  169  and fourth power output shaft. 
         [0079]    Thus, the invention provides an engine where power take-off is truly balanced such that the piston runs truly parallel to the cylinder walls, that provides improved gas mileage by reducing piston drag, and that produces greater torque. 
         [0080]    Although the present invention has been described in considerable detail with reference to certain embodiments, one skilled in the art will appreciate that the present invention can be practiced by other than the described embodiments, which have been presented for purposes of illustration and not of limitation. Therefore, the scope of the appended claims should not be limited to the description of the embodiments contained herein.