| 摘要 |
An electrically driven power steering device is configured such that, between the outer peripheral surface of a front end-side bearing (9a), which is fitted over and supports the front end of a worm shaft (6a), and the inner peripheral surface of a retention recess (10a) in a housing (3a), there are a guide piece (30) which is provided while being not circumferentially displaceable and a wedge piece (39) which is provided while being circumferentially displaceable. The electrically driven power steering device adopts a structure in which, when the wedge piece (39) is circumferentially displaced by the elastic force of a coiled spring (28) for the wedge piece, both a wedge surface (45) which is provided on the inner peripheral surface of the wedge piece (39) and a guide surface which is provided on the inner peripheral surface of the guide piece (30) press the outer peripheral surface of the front end-side bearing (9a) toward a worm wheel (4), eliminating backlash in a meshing portion. As a result, in this structure, worm teeth are prevented from being displaced both in the direction in which the worm teeth and the worm wheel mesh with each other and in the direction perpendicular to the axial direction of the worm shaft, thereby preventing tooth hitting noise from being generated at the meshing portion when rotational vibration is applied to a steering rotating shaft from the wheel side. |
