JPS608157A - Rack guide for rack-pinion steering system - Google Patents

Abstract

PURPOSE:To reduce the hitting noise and to prevent crack due to the difference of thermal expansion against the surface material coating the core member, by forming the core member of rack guide with thermoplastic resin mixed with 20-40wt% of glass fiber. CONSTITUTION:The core member 5b of rack guide 5 is formed with thermoplastic resin mixed with 20-40wt% of glass fiber. The surface member 5a coating the core member 5b is formed with resin having low friction factor. Consequently, the hitting noise can be reduced while crack caused by the difference of thermal expansion against the surface member coating the core member can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a rack guide for a rack and pinion type steering device.

This type of rack guide is equipped with a bearing (2
), the other end of which is supported in a 70-prong state, is brought into elastic contact with the back surface of the rack (3) in order to mesh it with the pinion (4) connected to the steering without backlash. The rack guide (5) is formed into a cylindrical shape with the arcuate concave portion on the lower surface as the elastic contact surface, and is connected to the former cylindrical guide chamber (6) protruding from the gear box [1]. ) and placed on the top surface of the spring (7).
) is brought into elastic contact by compressing it through a screw (8) screwed into the chamber (6). And the guide (5
) has low frictional resistance to allow the rack (3) to slide smoothly, and has high compression resistance against vibrations and impact loads transmitted to the rack (3), and also has high resistance to impact loads. It is required that there be little lead shot sound when receiving the lead shot, etc.
In order to fully satisfy such requirements, one of the applicants of the present invention previously published Utility Model Application No. 57-115073 to develop a rack guide (5mm) with a low friction coefficient (as shown in Figure 6) made of a resin skin material (5mm). ) with high compressive strength resin core material (5
b) was proposed.

A resin core material with high compressive strength mixed with glass fiber m has been disclosed, but the compressive strength of the core material increases as the degree of glass fiber mixed therein increases, resulting in the following problems.

One of them is that the sound quality of the hammering sound is higher and the transmission of illiteracy is better, so the hammering sound becomes louder.
Cracks occur during use due to the difference in thermal expansion between the core material and the corrugated skin material.

The inventors of the present invention have conducted various studies to improve these drawbacks and have found a solution.

That is, a core material with high compressive strength can be obtained by mixing glass fiber, but if the percentage of glass fiber mixed is less than 20% by weight, the core material cannot reliably support the return of the rack. Therefore, it is confirmed that a mixing rate of 20% or more is required, and if the mixing rate is increased further, the above-mentioned problem will occur, so from this point, the mixing rate needs to be 40% or less by weight. This confirms that something is true.

C is a thermoplastic resin containing glass fiber, such as PUT resin, nylon 66, or polyacetal resin.
An oil-impregnated plus sack such as 1h nylon 661 @ former nylon 12 was used, and the resin layer was 2 mm or less.

A desirable combination of resins is to use polybutylene terephthalate reinforced with 30% glass fiber, which has low hygroscopicity and excellent dimensional stability, for the core material (5b), and has relatively low dimensional change for the skin material (5a). Those using oleoresinous acetal resin give good results. If heat resistance is required, the core material is glass fiber-reinforced polyphenylene sulfide resin, and the skin material is oil-impregnated nylon 66.
Good results were obtained using resin.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a cross-sectional view of the steering device, FIG. 2 is a cross-sectional view taken along line A-A in FIG. 1, and FIG. 3 is a cross-sectional view of the rack guide. . (3)...Rack (4)...Pinion (5)...Rack guide (5a)...Skin material (5b)...Core material patent Applicant: 2 people other than Sumitomo Electric Industries, Ltd.

Claims (1)

[Claims] A rack and pinion type steering device in which a cylindrical rack guide is brought into elastic contact with the rack that meshes with the pinion, and the core rack guide is formed of a resin core material with high compressive strength covered with a resin skin material with a low coefficient of friction. 1. A rack guide for a rack and pinion type steering device, characterized in that the core material is made of a thermoplastic resin mixed with glass fiber of 20 to 40% in terms of single weight jtl ratio.