ELECTRIC POWER STEERING DEVICE

PROBLEM TO BE SOLVED: To suppress an increase in torque ripple of a motor when there is an input from the outside in an electric power steering device.SOLUTION: A shaft coupling 58 is interposed between a worm and a motor and includes: a first transmission member 60 provided on the motor side; and a second transmission member 62 provided on the worm side. A radial direction intermediate member 84 is arranged in a region held by a small diameter cylindrical section 70 of the first transmission member 60 and a large diameter cylindrical section 78 of the second transmission member 62 in a radial direction. The radial direction intermediate member 84 is constituted of an elastic material and has protrusion sections arrayed at intervals in a circumferential direction. The protrusion sections are high rigidity sections 86 while recesses between the protrusion sections are low rigidity sections 88. The low rigidity sections 88 are arranged substantially corresponding to positions generating a peak of torque. When force for decentering a rotor of the motor is input from the worm, eccentric force is hardly transmitted by the low rigidity sections 88, the decentering of the rotor is suppressed, and an increase in torque ripple is suppressed.SELECTED DRAWING: Figure 4 【課題】電動パワーステアリング装置に外部から入力があったときのモータのトルクリップルの増大を抑える。【解決手段】軸継手５８は、ウォームとモータの間に介在し、モータ側に設けられた第１伝達部材６０と、ウォーム側に設けられた第２伝達部材６２とを有する。径方向において、第１伝達部材６０の小径円筒部７０と第２伝達部材６２の大径円筒部７８に挟まれた領域に径方向中間部材８４が配置される。径方向中間部材８４は、弾性材料により構成され、周方向に凸部が間隔をあけて配列される。凸部が高剛性部８６、凸部の間の凹部が低剛性部８８である。トルクのピークが生じる位置に略対応して低剛性部８８が配置される。ウォームからモータのロータを偏心させる力が入力されるとき、低剛性部８８により偏心力が伝わりにくくなり、ロータの偏心が抑えられ、トルクリップルの増大が抑えられる。【選択図】図４