BOOT FOR CONSTANT VELOCITY UNIVERSAL JOINT

PROBLEM TO BE SOLVED: To provide a boot for constant velocity universal joint which improves durability and fatigue resistance even at an ultra-high actuation angle.SOLUTION: A boot 1 for constant velocity universal joint comprises: a large-diameter-side fitting part 4 which is mounted on an outer peripheral surface of an outer joint member 32 of a constant velocity universal joint 31, fastened and fixed by a boot band 5; a small-diameter-side fitting part 6 which is mounted on an outer peripheral surface of a shaft 46, fastened and fixed by a boot band 5'; and a bellows part 3 integrally coupling the large-diameter-side fitting part and the small-diameter-side fitting part. A cylindrical shoulder part 2 is formed in the large-diameter-side fitting part, and the large-diameter-side fitting part is connected from the cylindrical shoulder part through two auxiliary peak parts 3c and one auxiliary valley part 3d between the auxiliary peak parts to the bellows part. A radial distance between the auxiliary peak part and the auxiliary valley part is made shorter than a radial distance between a peak part 3a and a valley part 3b of the bellows part. A diameter passing a center of the radial distance between the auxiliary peak part and the auxiliary valley part is made larger than a diameter of the cylindrical shoulder part. At a high actuation angle of the constant velocity universal joint, the auxiliary peak part is deformed so as to be overlapped radially on an outer peripheral surface of an outer joint member.SELECTED DRAWING: Figure 1 【課題】超高作動角においても耐久性、耐疲労性が良好な等速自在継手用ブーツを提供すること。【解決手段】等速自在継手３１の外側継手部材３２の外周面に装着され、ブーツバンド５により締付け固定される大径側取付部４と、シャフト４６の外周面に装着され、ブーツバンド５'により締付け固定される小径側取付部６と、大径側取付部と小径側取付部を一体に連結する蛇腹部３とからなる等速自在継手用ブーツ１において、大径側取付部に筒状肩部２を形成し、筒状肩部から２つの補助山部３ｃと補助山部間の１つの補助谷部３ｄを介して蛇腹部に接続し、補助山部と補助谷部間の半径方向距離を、蛇腹部の山部３ａと谷部３ｂ間の半径方向距離より短くすると共に、補助山部と補助谷部間の半径方向距離の中心を通る直径を、筒状肩部の直径より大きくし、等速自在継手が高作動角のとき、補助山部が外側継手部材の外周面上で半径方向に重なる変形をさせることを特徴とする。【選択図】図１