| 摘要 |
<P>PROBLEM TO BE SOLVED: To effectively reduce tooth hitting sound generated in a worm gear speed reducing device used a drive transmission system transmitting the rotation of a motor driven in response to steering to a steering mechanism by a simple construction not by elastic support of a worm shaft. <P>SOLUTION: A coupling hole 4 is provided to the shaft end portion of the output shaft 27 of a motor M for assisting steering, a coupling tube 5 is provided to the shaft end portion of the worm shaft 21, the coupling tube 5 is fitted into the coupling hole 4, and the motor shaft 27 and the worm shaft 21 is coupled so as to be able to transmit the rotation by the engagement of the spline on an engaging periphery. A spiral notch groove 51 reaching an inner hole 50 is formed in the peripheral wall of the coupling tube 5. The generation of the tooth hitting sound at a meshing portion is inhibited, because the worm shaft 21 is displaced to perform a damping action by the deformation of the coupling tube 5 with the increase and decrease of the width of the notch groove 51, when the impact from the meshing portion with a worm wheel 22 is applied to the worm shaft 21 in a coupling condition. <P>COPYRIGHT: (C)2004,JPO |
