Steering system

Abstract

To provide a steering device that is able to restrict an increase in the size of a sector shaft.SOLUTION: In a steering device (PS1) according to the present invention, a preload applying mechanism (6) is configured to apply rotational torque toward one side in a rotational direction of a ball nut (4), based on a reaction force generated by a plunger (61) coming into elastic contact with the tips of first sector teeth (321) of a sector gear (32). Therefore, in the steering system (PS1), it is not necessary to provide a to-be-pressed portion that is pressed by the plunger (61), separately from the sector gear (32) as in the conventional steering system. This makes it possible to suppress an increase in the size of a sector shaft (3) due to the formation of the to-be-pressed portion.SELECTED DRAWING: Figure 2

Claims

1. Rack teeth formed on the outside of a ball nut that screws onto the steering shaft linked to the steering wheel, A sector gear is provided on a sector shaft linked to a steering wheel, and includes a central tooth that meshes most deeply with the rack teeth at the neutral position of the sector shaft, which corresponds to the straight steering state, and has a plurality of sector teeth arranged in the circumferential direction of the sector shaft that mesh with the rack teeth, A preload application mechanism that adjusts the meshing between the rack teeth and the sector gear near the neutral position of the sector shaft, Equipped with, The preload application mechanism is, In a cross-section perpendicular to the rotation axis of the steering shaft, the plunger receiving hole is formed in a sloping shape that gradually approaches the meshing direction line perpendicular to the rotation axis of the steering shaft and the rotation axis of the sector shaft, moving from the steering shaft side toward the rack teeth side, and opens at one end in the tooth width direction of a specific tooth root of the rack teeth that faces the tooth tip of the central tooth near the neutral position of the sector shaft, A plunger is housed in the plunger receiving hole so as to be able to move back and forth, and its tip is provided to protrude from the opening of the plunger receiving hole facing the sector gear, A biasing member interposed between the bottom of the plunger receiving hole and the plunger, biasing the plunger toward the central tooth, It has, The tooth root of the sector gear is a flat surface parallel to the axis of the sector shaft, Based on the reaction force generated when the plunger, which is biased by the biasing member, elastically contacts the tooth tips of the central tooth, the ball nut is biased to one side in the rotational direction of the ball nut. A steering device characterized by the following features.

2. A steering device according to claim 1, The plunger receiving hole is provided in a cross-section perpendicular to the rotation axis of the steering shaft so as to pass through the ball nut, and has a first opening that opens toward the rack teeth side and a second opening that opens toward the ball nut side. The bottom of the plunger receiving hole is formed by a plug that is screwed into the second opening of the plunger receiving hole. A steering device characterized by the following features.

3. A steering device according to claim 2, The plunger has a large-diameter portion that slides inside the plunger receiving hole, and a small-diameter portion that is formed in a stepped manner with respect to the large-diameter portion and is provided to protrude from the first opening. The plunger receiving hole is formed by reducing the diameter of the first opening so that its inner diameter is smaller than the outer diameter of the large diameter portion, and has a stopper that restricts the amount of protrusion of the small diameter portion by contacting the large diameter portion. When the rotational phase of the sector shaft is near the neutral position, the large-diameter portion does not come into contact with the stopper, while contact between the plunger and the central tooth is permitted. When the rotational phase of the sector shaft exceeds the vicinity of the neutral position, the large-diameter portion abuts against the stopper, thereby restricting contact between the plunger and the central tooth. A steering device characterized by the following features.

4. A steering device according to claim 1, The sector shaft is connected to the pitman arm, and one end on the axial side of the sector gear is formed to be relatively large in diameter, while the other end on the axial side of the sector gear is formed to be relatively smaller in diameter than the one end on the axial side. The plunger receiving hole opens at the end of the tooth width direction of the specific tooth root, which corresponds to the other axial end of the sector shaft. A steering device characterized by the following features.

5. A steering device according to any one of claims 1 to 4, A steering device characterized in that the biasing member is composed of a coil spring.

Images