JPS619369A - Rack bush for rack-and-pinion type steering device - Google Patents

Abstract

PURPOSE:To check the occurrence of a knock while keeping sliding resistance smaller, by forming an axial clearance in space between the outer circumferential surface of a rack and the inner surface of a cylindrical elastic body of a rack-and-pinion type steering device. CONSTITUTION:A rack bush is attached to the inside of a body cylinder part of a rack-and-pinion type steering device (unillustrated herein) and slidably inserted into each slide body 6. An inner diameter to be formed by each of these slide bodies 6 in due consideration of size tolerance is set so as to be larger or smaller as far as minute size value, and each of these slide bodies 6 makes a clearance with the rack 7 smaller, thus a knock is preventable from occurring. On top of that, even if the fitting between each hard slide body 6 and the rack 7 becomes tight fit, they are supported by a soft cylindrical ealastic body 2 so that sliding resistance between the slide body 6 and the rack 7 is small enough. In addition, each of these slide bodies 6 is provided with a sliding layer 6B having low friction and high abrasion resisting properties.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rack bushing that is used in a rack and pinion steering device and slidably supports a rack.

[Prior art and problems to be solved by the invention] Conventionally, bearings made of sintered metal have been generally used as rack bushings, but this type of rack bushing generates hammering noise when the gap with the rack becomes large. However, if it is too small, the sliding resistance will be too high, so high precision manufacturing is required.
It was expensive. For this reason, a rack bushing made of elastic synthetic resin has been proposed in order to suppress the occurrence of hammering noise while keeping sliding resistance low. However, this type of rack bushing does not have the above functions. The structure to hold it was complicated, and it was also expensive.

[Means and Effects for Solving the Problems 1] In view of the above-mentioned vehicle conditions, the present invention provides a plurality of sliding bodies harder than the elastic body on the inner surface of the cylindrical elastic body. With an extremely simple structure in which the rack is slidably supported and a gap is formed along the axial direction between the outer peripheral surface of the rack and the inner surface of the cylindrical elastic body, sliding resistance is kept small. To provide a rack bushing capable of suppressing the generation of hitting sounds.

[Example] The present invention will be explained below with reference to the illustrated example.
In FIG. 2, l is a metal cylindrical member, 2 is a cylindrical elastic body made of rubber or synthetic resin fitted into this cylindrical member l, and 1 is an engagement hole 3 formed in the cylindrical member 1. Inside,
By engaging an engaging protrusion 4 formed protrudingly on the outer circumferential surface of the cylindrical elastic body 2, the two are integrally connected. In addition,
The two may be connected by vulcanization, adhesive, or the like. Furthermore, both ends of the cylindrical member 1 may be caulked to enclose the cylindrical elastic body 2.

The cylindrical elastic body 2 has three axially extending protrusions 5 integrally formed at equal intervals on its inner surface, and a sliding body 6 having a U-shaped cross section is attached to each protrusion 5. . As shown in an enlarged view in FIG. 3, each sliding body 6 includes an arc-shaped sliding contact portion 6a that slides on the outer peripheral surface of the rack 7, and leg portions 8b on both sides of the sliding contact portion 6a. Each sliding body 6 is attached to the cylindrical elastic body 2 by inserting the tip end of the slider 6b into the groove 8 formed in the cylindrical elastic body 2. At this time, by setting the distance between the pair of legs 6b of the slider 6 in the free state to be slightly wider than the distance between the pair of grooves 8 into which the legs 6b are inserted, the slider 6 can be shaped into a cylindrical shape. Elastic body 2
This allows for secure installation.

-1-Reporter sliding body 6 consists of a back metal 6A made of metal material such as steel, and a sliding layer 6B made of a bearing base metal layer formed on this back metal BAJ- or a synthetic resin layer with low friction and excellent wear resistance. It consists of. By the way, the sliding body 6 described in (G) is usually manufactured by forming the sliding layer 6B on a plate-shaped back metal 6A-H and then bending it into a U-shape. There is a possibility that cracks may occur in the sliding layer 6B at the bent portion. When a crack occurs, abrasion powder is generated, which worsens the sliding condition, and the growth of the crack causes the back metal 6 to
A part of the sliding layer 6B is peeled off from A. For this reason, in this embodiment, the cutting portion 6C is provided at the bent portion indicated by -I-.
The cracks are removed by forming a
However, the sliding contact portion 8 of the reporter sliding body 6
The inner diameter formed by a is set to be larger or smaller than the outer diameter of the rack 7 by a microneedle. Therefore, if the rack is inserted between each sliding contact portion 6a, the clearance between the two will be small or zero. , the occurrence of hitting sounds is suppressed. The hardness of the cylindrical elastic body 2 is set in consideration of deformation when the sliding contact portions 6a and the rack 7 are tightly fitted together, the load applied to the rack 7, etc. The hardness of the entire sliding body 6 is set larger than that of the cylindrical elastic body 2 in consideration of wear resistance.

Furthermore, the amount of protrusion of each sliding body 6 from the inner surface of the cylindrical elastic body 2, that is, the gap 9 along the axial direction between the outer peripheral surface of the rack 7 and the inner surface of the cylindrical elastic body 2, The size is set so that it can be used as an air passage that communicates between the parts.

The rack bushing having the above configuration is installed inside the main body cylindrical part of a rack and pinion type steering device (not shown),
A rack 7 is slidably inserted into each sliding body 6. At this time, considering the dimensional tolerance, the inner diameter formed by each sliding body 6 is set to be slightly larger or smaller than the outer diameter of the rack 7, so each sliding body 6
By making the clearance between the rack 7 and the rack 7 small or zero, it is possible to suppress the occurrence of hitting sounds.

Moreover, even if each sliding body 6 and the rack 7 are tightly fitted, each sliding body 6 is supported by the relatively soft cylindrical elastic body 2, so each sliding body 6 and the rack 7
The sliding resistance between the two can be kept small. In addition,
Each sliding body 6 has a sliding layer 6B having low friction and high wear resistance.
, the sliding resistance is lower than that of a conventional rack bushing made of a solid synthetic resin material.

The gap 9 between the outer circumferential surface of the rack 7 and the inner surface of the cylindrical elastic body 2 can be used as an air passage communicating between both ends of the rack bushing, eliminating the need to provide a separate transfer tube. It can be eliminated.

In the first embodiment, the cylindrical elastic body 2 is fitted inside the cylindrical member l, but the cylindrical member 1 is omitted and the cylindrical elastic body 2 is inserted directly into the main body cylindrical part of the rack and pinion type steering device. body 2
It may also be fitted. Further, the groove 8 is formed by the sliding body 6.
The groove 8 is prevented from moving in the axial direction of the rack 7, but when the sliding body 6 is bonded to the protrusion 1.11 part 5, the groove 8 may be omitted, or as shown in FIG. When the adhesive portion LED is formed at the tip of the leg portion IBb of the moving body 16 and is adhered to the inner surface of the cylindrical elastic body 12, the protrusion portion 5 can also be omitted. In addition, in Figure 4, 1
1 is a cylindrical member, IEta is a sliding part, IBc is a cutting part, 1
8A is a backing metal, and IEiB is a sliding layer.

[Effects of the Invention] As described above, the present invention has an extremely simple structure in which a plurality of sliding bodies are provided on the inner surface of a cylindrical elastic body, and can reduce sliding resistance without requiring particularly high precision manufacturing. It is possible to suppress the occurrence of hammering noise while maintaining the rack bushing, and furthermore, the gap along the axial direction can be used as an air passage that communicates both ends of the rack bushing.

[Brief explanation of the drawing]

FIG. 1 is a front view showing one embodiment of the present invention, and FIG. 2 is a front view showing one embodiment of the present invention.
A sectional view taken along line H-II in the figure, Figure 3 is from ■-■ in Figure 2.
FIG. 4 is a sectional view along a line similar to FIG. 3 showing another embodiment of the present invention. 2.12... Cylindrical elastic body 6.18... Sliding body 7.
...Rack 9...Gap node 1 Fig. 1'' Fig. 2 ■ Fig. 3 Fig. 4

Claims (1)

[Claims] In the rack bushing of a rack and pinion type steering device that slidably supports a rack that is fitted into the cylindrical part of the main body of the rack and pinion type steering device and inserted through the shaft part, the inner surface of the cylindrical elastic body is A plurality of sliding bodies harder than the elastic body are provided, and the rack is slidably supported by the plurality of sliding bodies, and the outer peripheral surface of the rack and the inner surface of the cylindrical elastic body are spaced in the axial direction. A rack bushing for a rack-and-pinion steering device characterized by forming a gap along the .