摘要 |
<p>PROBLEM TO BE SOLVED: To provide reduction gear mechanism using a worm wheel made of resin, reducing cost by a large margin while ensuring sufficient gear accuracy. SOLUTION: In reduction gear mechanism for a motor-driven power steering constituted in such a way as to transmit the output of an electric motor to an output shaft 104 through reduction gear mechanism 107, 109 to assist steering force, the reduction gear mechanism is composed of a metallic worm 109 and a worm wheel 107 meshed with the worm 109. At least the tooth part, meshed with the worm 109, of the worm wheel 107 is formed of resin, and this tooth part assumes the shape of a spur gear with the tooth trace formed in straight lines parallel with the axis of the worm wheel 107. In addition, an expressionΣ=90 deg.-γ0 is materialized when the crossing angle of the axis of the worm and the axis of the worm wheel isΣand the advance angle of the worm isγ0 .</p> |