Patent ID: 7021269

Claim:
A lower link for use in a piston crank mechanism of an internal combustion engine, the piston crank mechanism including an upper link that has one end pivotally connected to a piston through a piston pin, the lower link that is of a split type including upper and lower half-parts coupled by a bolt and is pivotally connected to the other end of the upper link through an upper pin and pivotally disposed on a crank pin of a crankshaft and a control link that has one end pivotally connected to a fixed portion of the engine and the other end pivotally connected to the lower link through a control pin, the lower link comprising: a crank pin bearing housing portion adapted to receive the crank pin, the crank pin bearing housing portion defining a first contour; an upper pin receiving bore portion adapted to receive the upper pin, the upper pin receiving bore portion defining a second contour; a control pin receiving bore portion adapted to receive the control pin, the control pin receiving bore portion defining a third contour; a given portion that has therein an internally threaded bore formed in one of the upper and lower half-parts of the lower link and a bored portion formed in the other of the upper and lower half-parts of the lower link, the given portion defining a fourth contour, the upper and lower half-parts being coupled by the bolt that passes through the bored portion and is engaged with the internally threaded bore; and radially projected portions that extend radially outward beyond an imaginary minimum reference contour that is provided by connecting outer edge portions of the first, second, third and fourth contours with a continuous line.