JP2023102403A5 - - Google Patents

Description

The assist side pinion housing 16 is a portion that houses the assist side pinion shaft 13, and is disposed in a circumferential portion of the other axial side portion of the rack housing 14. Specifically, the assist side pinion housing 16 is disposed in the upper portion (upper portion in FIG. 2, rear portion in FIG. 3) of the other axial side portion of the rack housing 14. The assist side pinion housing 16 is disposed with its central axis facing the front-rear direction, and has a cylindrical shape with both ends in the front-rear direction open. The rear end opening of the assist side pinion housing 16 is closed by a cap 21a. The internal space of the assist side pinion housing 16 is connected to the internal space of the rack housing 14. The assist side pinion housing 16 is disposed in a twisted positional relationship with respect to the rack housing 14. In this example, the central axis of the assist side pinion accommodating portion 16 is disposed in a direction perpendicular to the central axis of the rack accommodating portion 14 when viewed from the top-bottom direction, which is a direction perpendicular to the central axis of the assist side pinion accommodating portion 16 and the central axis of the rack accommodating portion 14. However, when implementing the present invention, the central axis of the assist side pinion accommodating portion can also be disposed in an oblique direction when viewed from a direction perpendicular to the central axis of the assist side pinion accommodating portion and the central axis of the rack accommodating portion.

In this embodiment, the tension of the belt 58 is used to apply a force to the driven pulley 57 in a direction toward the driving pulley 56, i.e., a downward force. This biases the worm shaft 46, to the base end of which the driven pulley 57 is fixed, toward the worm wheel 45 (the lower side in FIG. 5). As a result, the worm shaft 46 is swung about the rolling bearing 49a on the tip end side, and the worm teeth 48 provided on the outer circumferential surface of the worm shaft 46 are pressed against the wheel teeth 47 provided on the outer circumferential surface of the worm wheel 45. This reduces backlash at the meshing portion between the worm teeth 48 and the wheel teeth 47, and prevents abnormal noise from being generated at the meshing portion between the worm teeth 48 and the wheel teeth 47.