Patent ID: 7669573

Claim:
A balancer mechanism for an internal combustion engine, comprising: a piston; a cylinder block having the piston reciprocably disposed within a cylinder chamber formed in an interior of the cylinder block, the cylinder block being disposed so that an axis of the cylinder chamber is tilted in a substantially horizontal direction; a crankshaft accommodated in an interior space of a crankcase coupled to the cylinder block, and rotates in synchronization with the piston; a single balancer shaft that rotates in synchronization with the crankshaft; and a balancer weight provided to the balancer shaft and rotating integrally with the balancer shaft, for canceling out vibration resulting from reciprocating motion of the piston, wherein the crankcase is formed by joining upper and lower case halves together, the upper case half is coupled to the cylinder block, and a joining surface between the upper and lower case halves is formed so as to extend substantially vertically as seen in side view; and the balancer shaft is located below the crankshaft, and the crankshaft and the balancer shaft are sandwiched and supported between the upper and lower case halves with their center axes being located on the joining surface.