Patent ID: 7357104

Claim:
A piston crank mechanism for an engine having a piston in a cylinder, the piston crank mechanism comprising: an upper link having a first end operably coupled to a piston by a piston pin; a lower link having a first end, a second end, and a crankpin journal arranged therebetween, wherein the crankpin journal is rotatably coupled to a crankpin of a crankshaft, and the first end is arranged with an upper pin boss to be operably coupled to a second end of the upper link by an upper pin; and a control link having a first end operably coupled to an eccentric cam of a control shaft that is supported by an engine block and a second end operably coupled to a control pin boss arranged at the second end of the lower link by a control pin, wherein the crankpin journal of the lower link is arranged and dimensioned relative to the upper pin such that a projection area defined by projecting the width of the upper pin along a direction defined by a line passing through a center of the piston pin and a center of the upper pin does not obscure an area defined by the crankpin during operation of the crankshaft as viewed in an axial direction of the crankpin.