Abstract:
A piston assembly includes a piston comprising a piston base and a piston head spaced-apart from the piston base and a crankshaft between the piston head and the piston base and connected to the piston base.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of and incorporates by reference in its entirety U.S. provisional application No. 61/215,645, filed May 7, 2009 and entitled “Piston/wrist pin separation to reverse piston travel speed, lengthening combustion time and volume for complete fuel burn”. 
    
    
     FIELD OF THE INVENTION 
     The present disclosure relates to internal combustion engines. More particularly, the present disclosure relates to a piston assembly for an internal combustion engine in which combustion time and volume for complete fuel burn are increased. 
     BACKGROUND OF THE INVENTION 
     An exemplary conventional piston assembly for an internal combustion engine is generally indicated by reference numeral  1  in  FIGS. 1 and 5 . As illustrated in  FIG. 5 , the conventional piston assembly  1  includes a cylinder  2  having a cylinder interior  3 . A piston head  6  having a combustion surface  7  is disposed in the cylinder interior  3  for reciprocation therein during a combustion cycle. A combustion chamber  4  is defined in the cylinder interior  3  between the walls of the cylinder  2  and the combustion surface  7  of the piston head  6 . An elongated connecting rod  12  has a piston connecting end  16  which is pivotally attached to the piston head  6  via a wrist pin  15  and a crankshaft connecting end  13  which is opposite the piston connecting end  16 . A crankshaft  18  includes a crankshaft body  19  and a crankshaft lobe  20  extending from the crankshaft body  19 . The crankshaft lobe  20  of the crankshaft  18  is rotatably attached to the crankshaft connecting end  13  of the connecting rod  12  via a connecting pin  14 . Reciprocation of the piston head  6  in the cylinder interior  3  of the cylinder  2  throughout the combustion cycle causes the connecting rod  12  to rotate the crankshaft  18  about a crankshaft axis of rotation  22 . 
     The point of attachment between the piston head  6  and the connecting rod  12  at the wrist pin  15  is on the side of the crankshaft axis of rotation  22  which is proximate or nearer to the combustion surface  7  of the piston head  6 . Consequently, as the reciprocating piston head  6  travels from the top-dead-center (TDC) position (the left-hand diagram in  FIG. 5 ) to 90 degrees after TDC (the middle diagram in  FIG. 5 ) in the cylinder interior  3  during the first half of the power stroke, the connecting pin  14  traverses the top or proximal arc of rotation, or the arc of rotation which is nearer or proximal to the combustion surface  7 . Conversely, as the piston head  6  travels from 90 degrees after TDC (the middle diagram in  FIG. 5 ) to the bottom-dead-center (BDC) position (the right-hand diagram in  FIG. 5 ) during the second half of the power stroke, the connecting pin  14  traverses the bottom or distal arc of rotation, or the arc of rotation which is further from or distal to the combustion surface  7  of the piston head  6 . As a result, the distance of travel of the piston head  6  from the TDC position to 90 degrees after TDC in the cylinder interior  3  is greater than the distance of travel of the piston head  6  from 90 degrees after TDC to the BDC position. This longer distance of travel of the piston head  6  during the first half relative to the second half of the power stroke results in incomplete combustion of fuel in the cylinder interior  3  throughout the combustion cycle. 
     Accordingly, a piston assembly is needed in which the distance of travel of the piston head from the TDC position to 90 degrees after TDC (the first half of the power stroke) is less than the distance of travel of the piston head from 90 degrees after TDC to the BDC position (the second half of the power stroke) to increase combustion time and provide a more constant volume for substantially complete fuel consumption during the initial part of the power stroke in an internal combustion engine. 
     SUMMARY OF THE INVENTION 
     The present disclosure is generally directed to a piston assembly. An illustrative embodiment of the piston assembly includes a piston comprising a piston base and a piston head spaced-apart from the piston base and a crankshaft between the piston head and the piston base and connected to the piston base. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The disclosure will now be made, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a perspective view of a piston head, connecting rod and crankshaft of an exemplary conventional piston assembly of an internal combustion engine; 
         FIG. 2  is a perspective view of a piston of an illustrative embodiment of the piston assembly of the present disclosure; 
         FIG. 3  is a perspective view of an illustrative embodiment of the piston assembly; 
         FIG. 4  is an exploded perspective view of a crankshaft bearing which is suitable for implementation of an illustrative embodiment of the piston assembly; 
         FIG. 5  illustrates side views of a piston of a conventional piston assembly at top dead center, 90-degrees after top dead center and bottom dead center positions, respectively, of the piston; and 
         FIG. 6  is a side view of an alternative illustrative embodiment of the piston assembly, with a crankshaft bearing block provided on each spacer rod of the piston. 
     
    
    
     DETAILED DESCRIPTION 
     The following detailed description is merely exemplary in nature and is not intended to limit the described embodiments or the application and uses of the described embodiments. As used herein, the word “exemplary” or “illustrative” means “serving as an example, instance, or illustration.” Any implementation described herein as “exemplary” or “illustrative” is not necessarily to be construed as preferred or advantageous over other implementations. All of the implementations described below are exemplary implementations provided to enable persons skilled in the art to practice the disclosure and are not intended to limit the scope of the claims. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding technical field, background, brief summary or the following detailed description. 
     Referring to  FIGS. 2 ,  3  and  6  of the drawings, an illustrative embodiment of a piston assembly is generally indicated by reference numeral  30  in  FIGS. 3 and 6 . The piston assembly  30  may be a single piston assembly or one of multiple piston assemblies in an internal combustion engine. The piston assembly  30  may include a cylinder  31  having a cylinder interior  32 . A piston  36  of the piston assembly  30  is reciprocally mounted in the cylinder interior  32  of the cylinder  31 . As illustrated in  FIG. 2 , the piston  36  of the piston assembly  30  may include a piston base  37  on which is provided a pair of spaced-apart base flanges  38 . A pin opening  39  may extend through each base flange  38  for purposes which will be hereinafter described. 
     At least one and typically multiple elongated spacer rods  42  may extend from the piston base  37  in spaced-apart relationship with respect to each other. A piston head  44  having a combustion surface  45  may be provided on the spacer rods  42  in spaced-apart relationship with respect to the piston base  37 . As illustrated in  FIG. 6 , when the piston  36  is reciprocally mounted in the cylinder interior  32  of the cylinder  31 , a combustion chamber  33  is defined in the cylinder interior  32  between the combustion surface  45  of the of the piston head  44  and the wall of the cylinder  31 . Multiple piston rings  46  may be provided on the piston head  44  to provide a seal between the piston head  44  and the interior surface of the cylinder  31 , as is known by those skilled in the art. Fuel intake and exhaust outlet valves (not illustrated) may be provided at the combustion chamber  33  end of the cylinder  31  for the introduction of fuel and evacuation of exhaust from the combustion chamber  33 , respectively, as is known by those skilled in the art. 
     A crankshaft  50  is attached to the piston  36  via a connecting rod  56 . The crankshaft  50  may have a crankshaft body  51 . A crankshaft lobe  52  may extend from the crankshaft body  51 . Connecting shafts  55  may connect adjacent crankshaft bodies  51  to each other in the crankshaft  50 . The crankshaft  50  is adapted to rotate about a crankshaft axis of rotation  53  throughout reciprocation of the piston  36  in the cylinder interior  32  during a combustion cycle, as will be hereinafter described. The connecting rod  56  may have a piston connecting end  57  which is rotatably attached to the piston base  37  of the piston  36  via a wrist pin  48  ( FIG. 6 ). The wrist pin  48  may be extended through the pin openings  39  ( FIGS. 2 and 3 ) provided in the base flanges  38 . A crankshaft connecting end  58  is opposite the piston connecting end  57  of the connecting rod  56  and is rotatably attached to the crankshaft lobe  52  of the crankshaft  50  via a connecting pin  59  ( FIG. 6 ). The point of attachment of the connecting rod  56  with the piston  36  at the wrist pin  48  may be on the side of the crankshaft axis of rotation  53  ( FIG. 6 ) which is distal to or further from the combustion surface  45  on the piston head  44  of the piston  36 . In  FIG. 6 , the piston  36  is shown at 90 degrees after TDC. As the piston  36  travels from TDC to 90 degrees after TDC ( FIG. 6 ) in the combustion chamber  33  during the first half of the power stroke of the piston  36 , the connecting pin  59  traverses the bottom or distal arc of rotation, or the arc of rotation which is distal to or further from the piston head  44  (distal arc of rotation). Consequently, the distance of travel of the piston head  44  from TDC to 90 degrees after TDC is smaller than the distance of travel of the piston head  44  from 90 degrees after TDC to BDC. 
     In typical application, the piston assembly  30  may be a single piston assembly in a small internal combustion engine (not illustrated) or may be one of multiple piston assemblies  30  in a multi-cylinder internal combustion engine. Moreover, the multiple piston assemblies  30  may be arranged in a straight configuration, a V-configuration, a flat or horizontally-opposed configuration or any other desirable configuration which is suitable for the purpose. The cylinder  31  ( FIG. 6 ) of each piston assembly  30  may be fitted with injection and exhaust valves, spark plugs, electronic fuel injection components and/or other components which are necessary for the introduction of a fuel/air mixture into the combustion chamber  33  and combustion of the fuel, as well as evacuation of the exhaust from the combustion chamber  33 , according to the knowledge of those skilled in the art. The crankshaft  50  may be coupled to a flywheel (not illustrated) for automotive applications or other element or component depending on the desired application. 
     As a fuel/air mixture is ignited in the combustion chamber  33 , the piston  36  commences the power stroke phase of the combustion cycle and travels from TDC to 90 degrees after TDC ( FIG. 6 ). At the 90 degrees after TDC position, the longitudinal axis of the crankshaft lobe  52  of the crankshaft  50  is oriented at 90 degrees with respect to a longitudinal axis of the cylinder  31 . During this transition of the piston  36 , the connecting pin  59  between the crankshaft  50  and the connecting rod  56  traverses the bottom or distal arc of rotation of the crankshaft  50 . As the piston  36  next continues to travel from 90 degrees after TDC to BDC ( FIG. 3 ) and back to TDC, the connecting pin  59  completes rotation. Consequently, during each combustion cycle, the combustion volume of chamber  33  fluctuates less during the combustion period and therefore, substantially all of the fuel which is introduced into the combustion chamber  33  is consumed, resulting in an efficient power stroke of the piston  36  as well as emission of clean exhaust from the internal combustion engine of which the piston assembly  30  is a part. 
     Referring next to  FIGS. 4 and 6  of the drawings, in some illustrative embodiments of the piston assembly  36 , a crankshaft bearing  62  may be provided on each spacer rod  42  of the piston  36 . As illustrated in  FIG. 4 , each crankshaft bearing  62  may include a generally elongated bearing block  63 . A rod opening  64  may extend through the longitudinal dimension of the bearing block  63  to receive the corresponding spacer rod  42  of the piston  36 . A generally concave shaft cavity  65  may be provided in a side surface of the bearing block  63 . Accordingly, as illustrated in  FIG. 6 , a pair of crankshaft bearings  62  may be mounted on a respective pair of the spacer rods  42  with the shaft cavities  65  ( FIG. 4 ) of the crankshaft bearings  62  facing each other. A connecting shaft  55  of the crankshaft  50  may extend through the opposing shaft cavities  65  of the respective crankshaft bearings  62 . Therefore, the inner surfaces of the respective shaft cavities  65  provide a bearing surface for the connecting shaft  55  of the crankshaft  50  as the piston  36  rotates the crankshaft  50  about the crankshaft axis of rotation  53  ( FIG. 9 ). 
     While illustrative embodiments of the disclosure have been described above, it will be recognized and understood that various modifications can be made and the appended claims are intended to cover all such modifications which may fall within the spirit and scope of the disclosure.