Balance shaft for engine balancing systems

摘要

In a balance shaft (13R,13L) for engine balancing systems for canceling an unbalance force of an engine, a journal portion (18) of the balance shaft is provided with a recess (22) on a side remote from the gravitational center of the counter weight, and a rib (23) extends axially across this recess along a radial plane between full circular axial end portions of the journal portion to compensate for the reduction in the bending rigidity of the balance shaft due to the provision of the recess. The recess reduces the weight or mass of the balance shaft, and this recess does not diminish the performance of the bearing because the bearing load is essentially due to the unbalanced mass of the counter weight portion, and the recessed part of the bearing portion receives a significantly smaller part of the bearing load than the opposite side of the bearing portion. The recessing also contributes to increasing the eccentricity of the gravitational center of the associated part.