Reduced mass crankshaft

摘要

A crankshaft for an engine having an odd number of cylinders is provided. In one example, the crankshaft includes a central pin coupling a first and a second asymmetric counterweight and a pair of pins coupling cheeks absent counterweights. The crankshaft can improve engine balance at least during some conditions.

主权项

1. A crankshaft for an engine, comprising:
a central pin directly coupling a first counterweighted cheek to a second counterweighted cheek, the first and second counterweighted cheeks being asymmetric on reflection in a plane orthogonal to a rotation axis of the crankshaft and passing between the first and second counterweighted cheeks; a first outer pin arranged forward of the central pin in a direction parallel to the rotation axis, the first outer pin directly coupling a first pair of non-counterweighted cheeks; and a second outer pin arranged rearward of the central pin in the direction parallel to the rotation axis, the second outer pin directly coupling a second pair of non-counterweighted cheeks, where a total number of crankpins of the crankshaft, including the first and second outer pins and the central pin, is an odd number.