JPH0148190B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rack and pinion type steering device which is generally used as a steering device for automobiles.

A rack and pinion steering system used as a steering device for an automobile consists of a pinion that rotates when the steering wheel is rotated, and a rack shaft that has rack teeth that mesh with the pinion and slides in the axial direction as the pinion rotates. The device is generally used (for example, Japanese Utility Model Application Publication No. 54-69532, Japanese Utility Model Application No. 69532,
(See Publication No. 55-132449, etc.)

As shown in FIG. 1, the above-mentioned rack and pinion type steering device is constructed by connecting an intermediate shaft 4 via a joint 3 to the tip of a steering shaft 2 having a steering wheel 1 attached to one end thereof. A pinion shaft 6 is connected to the pinion shaft 6 through a joint 5, and by rotating the steering wheel 1, the pinion shaft 6 rotates, and a rack shaft 7 that meshes with the pinion shaft 6a of the pinion shaft 6 slides in the axial direction. However, during the above-mentioned steering operation, a bending moment is applied to the pinion shaft 6 due to the secondary torque of the joints 3 and 5, and especially when the pinion shaft 6 is long as shown in the first figure, the joint A problem arises in that the bending moment caused by the secondary torque increases the friction of the bearing 9 for supporting the pinion shaft 6.

Therefore, when the pinion shaft 6 is long as described above, conventionally the pinion shaft 6 is placed above the gear case 8.
In many cases, a method of supporting the pinion shaft using three lower and middle bearings is adopted, but if a method of supporting the pinion shaft with three bearings is adopted in this way, the accuracy of the line through between the three bearings will be reduced. This creates the problem that manufacturing is extremely complicated and expensive.

The present invention is intended to address the conventional problems as described above, and will be described below with reference to the embodiment shown in FIG.

In the present invention, as shown in FIG.
The lower end and the vicinity of the upper end are rotatably supported by the gear case 8 via bearings 9a and 9b, and the pinion tooth 6a is located at a position near the upper end of the pinion tooth 6a, which is approximately in the middle of the support by both bearings 9a and 9b. A supported surface 6b is formed on the gear case 8, and an intermediate bearing 9c is located at a position opposite to the supported surface 6b of the gear case 8, and the inner peripheral supporting surface thereof has a predetermined minute gap δ with the supported surface 6b of the pinion shaft 6. It is characterized by being provided so as to face each other.

In FIG. 2, the pinion teeth 6a of the pinion shaft 6
meshes with the rack teeth 7a of the rack shaft 7 which is supported by the gear case 8 so as to be slidable in the axial direction, and when the steering wheel is rotated, the rotational torque is transmitted from the steering shaft through the intermediate shaft connected by the joint. Needless to say, the rotation is transmitted to the pinion shaft 6 to rotate the pinion shaft 6, and the rack shaft 7 slides in the axial direction to effect steering. Note that 10 in FIG. 2 indicates an oil seal.

According to the present invention configured as described above, even if the pinion shaft 6 is long, the span between the two support points by the bearings 9a and 9b near the lower and upper ends is long, so that the bending moment based on the secondary torque of the joint can be reduced. The load applied to the bearings 9a and 9b can be significantly reduced, and when a large torque is applied to the rack shaft 6 and deflection occurs between the support points of the bearings 9a and 9b at both ends, a part of the intermediate supported surface 6b are in sliding contact with the intermediate bearing 9c to minimize the deflection and both end bearings 9a,
This prevents an increase in friction at the portion 9b.

Furthermore, as mentioned above, since the intermediate bearing 9c has a structure in which a gap δ is provided between the intermediate bearing 9c and the supported surface 6b of the rack shaft 6, the line-through accuracy of the three bearings 9a, 9b, and 9c is not very strict. Therefore, not only is it extremely easy to manufacture, but the intermediate bearing 9c only slides and supports the supported surface 6b only when a large torque is applied to the rack shaft 6, and normally supports the supported surface 6b. Since the intermediate bearing 9c is not in contact with the intermediate bearing 9c, there is no need to use a ball bearing like the both end bearings 9a and 9b, and a simple structure such as a sintered bushing can sufficiently perform the intended function. I can,
It also has the advantage of being extremely advantageous in terms of cost, and can bring about great practical effects.

[Brief explanation of drawings]

FIG. 1 is a side view schematically showing a rack and pinion steering device to which the present invention is applied;
The figure is a sectional view of a pinion shaft support part showing an embodiment of the present invention. 6...Pinion shaft, 6a...Pinion tooth, 6b
... Supported surface, 7 ... Rack shaft, 7a ... Rack tooth, 8 ... Gear case, 9a, 9b ... Bearing, 9c ... Intermediate bearing.

Claims (1)

[Claims] 1. In a rack and pinion type steering device in which a pinion shaft that rotates when a steering wheel is rotated and a rack shaft that has rack teeth that mesh with the pinion teeth of the pinion shaft are attached to a gear case, the upper end of the pinion shaft The adjacent portion and the lower end portion are rotatably supported by the gear case using upper and lower bearings, and a supported surface is formed at a position near the upper end of the pinion tooth, which is approximately the middle position of the supported portion by the upper and lower bearings of the pinion shaft. A rack and pinion type steering device characterized in that a gear case is provided with an intermediate bearing that faces the supported surface with a small gap therebetween.