Patent ID: 7434560
Filing Date: 2008-10-14
Classification: F16F,Y10T

Abstract:
1. A balancing device for an engine, having a crankshaft rotatably supported in a crank case, two balancer shafts disposed below the crankshaft and having the axes thereof extending in parallel with the crankshaft, said balancer shafts being rotatably supported by at least two balancer shaft bearings and being disposed according to an axial direction of the balancer shaft, a first balancer weight disposed on the balancer shaft between the balancer shaft bearings, a second balancer weight cantilevered at a position opposing the first balancer weight, the other balancer shaft bearing being positioned between the balancer weights, and the balancing device permitting the inertia forces generated by the first and the second balancer weights to be applied to the center of gravity of a piston-connecting rod system for compensating a secondary inertia force generated by the engine, comprising the improvement wherein the balancer shaft bearing between the first and the second balancer weights is displaced toward the second balancer weight according to the axial direction of the balancer shaft for a certain distance from an intersection Y of an axis of the balancer shaft with a plane passing through the center of gravity Gp of the piston-connecting rod system so that a distance L 2 between the intersection Y and the center of gravity G 2 of the second balancer weight is longer than a distance L 1 between the intersection Y and the center of gravity G 1 of the first balancer weight and so that the moment created at the intersection Y by the inertia force F 1 of the first balancer weight and the moment created at the intersection Y by the inertia force F 2 of the second balancer weight are balanced.