JPS621012Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a rack and pinion type steering gear device in a steering system of a vehicle such as an automobile.

As one of the steering gear devices in a vehicle steering system, a rack of a rack bar is engaged with a pinion of a steering shaft in a gear box, and rotation of the steering shaft drives the rack bar in its axial direction. A so-called rack and pinion type steering gear device is known. In such a rack and pinion steering gear device,
Generally, in order to increase the support rigidity of the rack bar at the part where it meshes with the pinion, and to reduce the backlash between the pinion and the rack, the rack bar is attached to the outer peripheral surface of the rack bar by a spring on the side opposite to the pinion. It is supported by resiliently pressed rack guide elements.

Conventionally, in the above-mentioned rack and pinion type steering gear devices, the rack bar and the rack guide element are generally in surface contact with each other, and the rack bar is in sliding contact with the rack guide bar when moving in its axial direction. Therefore, the frictional resistance of the rack bar is large, and the rotational torque required to rotate the steering shaft is large.

In view of the above-mentioned problems, it has been considered to provide a rolling element such as a ball between the rack guide element and the rack bar so that the rack bar does not experience greater frictional resistance than the rack guide element during movement. There is.

As mentioned above, when the rolling element is provided, the frictional resistance that the rack bar receives from the rack guide element during its movement is reduced, and the rotational torque required to rotate the steering shaft is reduced; however, the diameter acting on the rack bar is reduced. All directional loads are transmitted to the rack guide element through the rolling elements, so that a compressive load acts locally on the contact area between the rack bar and the rolling element, especially when the rolling element is a ball. The rack bar and the rolling element come into point contact, and if a large radial load is applied to the rack bar, there is a risk that the rack bar will be depressed and deformed by the rolling element, reducing the durability of the rack bar and the rolling element. do.

In view of the above-mentioned problems with conventional rack and pinion type steering gear devices, the present invention can reduce the frictional resistance that the rack bar receives from the rack guide element when moving the rack bar, and furthermore, it is possible to reduce the frictional resistance that the rack bar receives from the rack guide element even when a large radial load is applied to the rack bar. It is an object of the present invention to provide an improved rack and pinion type steering gear device that does not cause concave deformation.

According to the present invention, a rack of a rack bar is engaged with a pinion of a steering shaft in a gearbox, and rotation of the steering shaft drives the rack bar in its axial direction, and the rack bar engages with the pinion of the steering shaft. In such a rack and pinion type steering gear device, the steering gear is supported by a rack guide element on the opposite side thereof, and a compression coil spring is elastically mounted between a cover element fixed to the gear box and the rack guide element. A rack and pinion type steering system, characterized in that a rolling element is provided between the rack bar and the rack guide element, and the rolling element is supported by an elastically deformable seat so that it can roll relative to the rack guide element. This is achieved by means of a gear system.

According to the above-described structure, during normal use when a large radial load is not applied to the rack bar, the rack bar is supported by the rack guide element in rolling contact with the rolling elements, so that the rack bar can move with low resistance. This reduces the rotational torque required to rotate the steering shaft. When a large radial load is applied to the rack bar, the seats of the rolling elements are elastically deformed, and as a result, the rack bar becomes directly supported by the rack guide elements.At this time, the rolling elements no longer function effectively, but the rack bar This prevents a large load from acting locally on the rack bar, and prevents concave deformation from occurring at the contact portion of the rack bar with the rolling element.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a sectional view showing one embodiment of a rack and pinion type steering gear device according to the present invention. In the figure, reference numeral 1 indicates a gear box of a steering gear device, and within this gear box, the tip of a steering shaft 2, on which a pinion 3 is formed, is rotated around its axis by a ball bearing 4 and a metal bearing 5. Rotatably supported. The pinion 3 meshes with a rack 7 of a rack bar 6 extending in a direction perpendicular to the axis of the steering shaft 2. Rack bar 6
is supported movably in the axial direction by the gearbox 1, and is configured to reciprocate in the axial direction when the steering shaft 2 is rotated.

Further, a rack guide element 8 is provided on the side of the rack bar 6 opposite to the side on which the rack 7 is provided, facing the pinion 3. The rack guide element 8 is a cylindrical member received in a cylindrical hole 9 formed in the gear box 1, and the end facing the cylindrical outer peripheral surface of the rack bar 6 has a cylindrical recess corresponding to the cylindrical outer peripheral surface. It is said to be 10.
The rack guide element 8 is attached to the rack bar by the spring force of a compression coil spring 13 installed with a predetermined preload between the rack guide element 8 and a cover element 12 screwed to the gearbox 1 to close the hole 9. It is designed to be elastically pressed toward the target.

The cylindrical recess 10 of the rack guide element 8 is provided with a plurality of blind holes 15, four in this embodiment, each of which has an elastically deformable ball seat made of synthetic resin. 16 and a ball 17 are provided. Each of the balls 17 can roll freely within the hole, and a part of the ball 17 protrudes outward from the bottom surface of the cylindrical depression 10, and the outer peripheral surface of the ball 17 is capable of rolling freely.
It is adapted to make substantially point contact with the cylindrical outer circumferential surface of.

When the rack bar 6 moves in its axial direction due to the rotation of the pinion 3, the balls 17 roll within the respective blind holes 15 accordingly. As a result, during normal use when a large radial load is not applied to the rack bar 6, the rack bar 6 and the rack guide element 8 are in a rolling contact relationship, compared to when they are in a sliding contact relationship as in the past. The rack bar 6 can now be moved in its axial direction with a small force, and the driving load of the steering system can be reduced compared to the conventional one. During normal use when the radial load acting on the rack bar 6 is not large, the rack bar 6 is supported by the balls 17, but when the radial load becomes large, the synthetic resin ball seat 16 that receives the balls 17 elastically deforms. As a result, the rack bar 6 is supported by the cylindrical recess 10 of the rack guide element 8, no excessive load is applied to the ball 17, and deformation of the ball 17 and the rack bar 16 is avoided.

In the above, the present invention has been described in detail with respect to specific embodiments, but the present invention is not limited to these, and those skilled in the art will recognize that various embodiments are possible within the scope of the present invention. It would be obvious to

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing one embodiment of a rack and pinion steering gear device according to the present invention, and FIG. 2 is an end view showing a rack guide element taken out. 1~Gearbox, 2~Steering shaft, 3~Pinion, 4~Ball bearing, 5~
Metal bearing, 6 - rack bar, 7 - rack, 8 - rack guide element, 9 - hole, 10 - cylindrical surface depression, 12 - cover element, 13 - compression coil spring, 15 - blind hole, 16 - ball seat, 17 ~ball.

Claims (1)

[Scope of utility model registration request] A rack of a rack bar is engaged with a pinion of a steering shaft in a gearbox, and rotation of the steering shaft drives the rack bar in its axial direction, and the rack bar is supported by a rack guide element on the side opposite to the pinion. In a rack and pinion type steering gear device in which a compression coil spring is elastically mounted between a cover element fixed to the gearbox and the rack guide element,
A rack and pinion type steering system, characterized in that a rolling element is provided between the rack bar and the rack guide element, and the rolling element is supported by an elastically deformable seat so that it can roll relative to the rack guide element. gear device.