Patent ID: 8714127

Claim:
A balance shaft module of an engine, comprising: a crank sprocket driving gear for receiving a power of a crankshaft of the engine; a crank sprocket driven gear operably engaged with the crank sprocket driving gear and receiving a power of the crank sprocket driving gear; a first balance shaft arranged coaxially with the crank sprocket driven gear and having a first driving gear to receive a power from the crank sprocket driven gear; and a second balance shaft receiving a power through a second driving gear engaged with the first driving gear; wherein a first balance weight element is mounted on the first balance shaft and includes first, second and third weight elements with a phase difference of 90 degrees in sequence; wherein a second balance weight element is mounted on the second balance shaft and includes fourth, fifth and sixth weight elements with a phase difference of 90 degrees in sequence; and wherein the first, second and third weight elements extend in an opposite direction than the fourth, fifth and sixth weight elements respectively, thereby offsetting unbalance forces and unbalance moments generated on the first balance shaft and the second balance shaft.