BALANCE SHAFT

PROBLEM TO BE SOLVED: To provide a balance shaft which is simple in a structure, and can be employed to a variety of engines having different specifications.SOLUTION: A balance shaft comprises: a shaft which rotates in conjunction with a crankshaft of an internal combustion engine; a pair of first masses which are constituted of members different from that of the shaft, arranged at both sides of the center of gravity of the shaft, and fixable to the shaft at an arbitrary angle; and a pair of second masses arranged at both the sides of the center of gravity of the shaft. When setting a mass of the first mass as m1, a rotation radius of the center of gravity of the first mass as r1, a distance between the center of gravity of the first mass and the center of gravity of the shaft in an axial direction of the shaft as L1, a mass of the second mass as m2, a rotation radius of the center of gravity of the second mass as r2, and a distance between the center of gravity of the second mass and the center of gravity of the shaft in the axial direction of the shaft as L2, a relationship of m1×r1×L1=m2×r2×L2 is established.SELECTED DRAWING: Figure 3 【課題】簡易な構造で、異なる仕様のエンジンに適用可能なバランスシャフトを提供する。【解決手段】バランスシャフトは、内燃機関のクランク軸に連動して回転するシャフトと、前記シャフトとは別部材で構成され、前記シャフトの重心の両側に設けられ、任意の角度で前記シャフトに固定可能な１組の第１マスと、前記シャフトの重心の両側に設けられた１組の第２マスと、を備え、前記第１マスの質量をｍ１、前記第１マスの重心の回転半径をｒ１、前記シャフトの軸方向における前記第１マスの重心と前記シャフトの重心との間の距離をＬ１とし、前記第２マスの質量をｍ２、前記第２マスの重心の回転半径をｒ２、前記シャフトの軸方向における前記第２マスの重心と前記シャフトの重心との間の距離をＬ２としたとき、ｍ１×ｒ１×Ｌ１＝ｍ２×ｒ２×Ｌ２の関係が成立する。【選択図】図３