JP2002087289A - Rack and pinion type steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rack and pinion type steering device capable of preferably avoiding creep of a synthetic resin sheet even for a long time load and an impact load even when a rack guide is formed of the synthetic resin sheet and smoothly, slidably supporting a rack bar for a long time. SOLUTION: The rack and pinion type steering device 1 comprises a gear case 3 having a hollow part 2, a steering shaft 6 supported by the gear case 3 rotatably in the R direction around a shaft core X through rolling bearings 4 and 5, a pinion 7 that is disposed in the hollow part 2 and integrally provided for the shaft end of the steering shaft 6, a rack bar 9 having a rack tooth 8 engaging with the pinion 7, and a rack guide means 10 that is disposed in the hollow part 2 of the gear case 3 and has the synthetic resin sheet for supporting the rack bar 9 slidably in the orthogonal direction of the shaft core X. The sheet engages with projecting strips 26 and 27 of a rack guide substrate 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile, etc., in which a pinion is rotated in conjunction with a turning operation of a steering wheel, and a rack bar having rack teeth meshing with the pinion is reciprocated for steering. The present invention relates to a rack and pinion type steering device used for a vehicle.

[0002]

A rack and pinion type steering apparatus of this type usually includes a gear case, a pinion rotatably supported on the gear case via a pinion shaft, and rack teeth meshing with the pinion. And a rack guide disposed in the gear case to slidably support the rack bar, and a spring for pressing the rack guide toward the rack bar.

In such a rack-and-pinion type steering device, forces that separate from each other act on the meshing portion between the rack teeth of the rack bar and the pinion with the rotation of the pinion shaft, causing the rack bar to bend. Since rattling in the tooth row direction becomes large, and a rattle is generated between the teeth of the rack teeth and the pinion, a rack guide is provided on the opposite side to the pinion shaft with the rack bar interposed. Press the guide to the pinion shaft side by the pressing force of the spring,
The rack guide slides on the rack bar to reduce the sliding resistance with the rack bar, and allows the rack bar to move smoothly in the axial direction while suppressing rattling of the rack teeth in the tooth row direction. The striking noise at the meshing portion between the rack teeth and the pinion is reduced.

In a rack and pinion type steering device in which a rack guide slides on a rack bar, usually,
The rack guide is made of an iron-based sintered metal or a synthetic resin.A rack guide made of an iron-based sintered metal has sufficient mechanical strength against an impact load from a rack bar. On the other hand, the synthetic resin rack guide, unlike the one made of iron-based sintered metal, can reduce the sliding friction resistance and does not hinder the steering performance so much, while In addition to having a problem in mechanical strength, there is also a problem that when the load is large, the sliding friction resistance increases.

[0005] In a synthetic resin rack guide, dimensional variations due to molding shrinkage and the like occur, and thermal expansion / shrinkage, thermal deformation, and creep (plastic flow) due to a rise in the temperature of the rack and pinion type steering device occur. In some cases, the rack bar cannot be smoothly slidably supported.

On the other hand, a rack guide base made of an iron-based sintered metal, aluminum, or a synthetic resin containing a reinforcing material is provided on the rack bar side surface of the rack guide base and has self-lubricating properties. When a rack guide is constituted by a wear-resistant synthetic resin sheet having a rack bar, and the rack bar is slidably supported by a rack guide having such a synthetic resin sheet interposed, the synthetic resin sheet is subjected to a long-term load and an impact load. Creep may occur, and it may be difficult to smoothly slide and support the rack bar.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a synthetic resin sheet that can be used even when a rack guide is formed using a synthetic resin sheet, even when a long-term load and an impact load are applied. Therefore, it is an object of the present invention to provide a rack and pinion type steering device capable of preferably avoiding the creep of the rack bar and smoothly supporting the rack bar for a long period of time.

[0008]

According to a first aspect of the present invention, there is provided a rack and pinion type steering apparatus having a gear case, a pinion rotatably supported by the gear case, and rack teeth meshing with the pinion. A rack bar having an arc-shaped outer peripheral surface facing the rack teeth, and a rack guide means for slidably supporting the rack bar, wherein the rack guide means is mounted in a gear case. And a rack guide base having an arc-shaped concave surface facing the arc-shaped outer peripheral surface of the rack bar, and being interposed between the arc-shaped outer peripheral surface of the rack bar and the arc-shaped concave surface of the rack guide base, A rack guide having an arc-shaped concave surface facing the arc-shaped outer peripheral surface of the rack bar and fixed to the arc-shaped concave surface of the rack guide base; The body has at least a pair of ridges extending in the sliding direction of the rack bar on its arcuate concave surface, and the synthetic resin sheet has a ridge in which the ridges of the rack guide base are fitted. The arc-shaped concave surface corresponding to the concave strip portion is in contact with the arc-shaped outer peripheral surface of the rack bar, and the synthetic resin sheet at each concave strip portion is adjacent to the concave strip portion on both sides and The thin portion is thinner than a portion that is not in contact with the arc-shaped outer peripheral surface of the rack bar.

According to the rack and pinion type steering apparatus of the first aspect, since the portion of the synthetic resin sheet that comes into contact with the arc-shaped outer peripheral surface of the rack bar is a thin portion, even in the case of a long-term load and an impact load, the thin resin portion can be used. Creep can be preferably avoided, and the rack bar can be smoothly slid and supported over a long period of time. That is, the present rack and pinion type steering device is based on the finding that a thin portion of a synthetic resin sheet has a smaller amount of creep than a thick portion, and such a thin portion is formed on the arc-shaped outer peripheral surface of the rack bar. In the rack-and-pinion type steering device according to the first aspect, which is disposed at the site of the contacting synthetic resin sheet, creep of the synthetic resin sheet at the contact portion can be preferably avoided as described above, and the rack bar can be smoothly moved for a long period of time. Can be slidably supported.

In the rack and pinion type steering apparatus according to the second aspect of the present invention, the rack and pinion type steering apparatus according to the first aspect includes:
The arc-shaped concave surface of the synthetic resin sheet has a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface of the rack bar.

When the arcuate concave surface of the synthetic resin sheet has a radius of curvature as in the second aspect, it is possible to secure contact of the rack bar with the arcuate outer peripheral surface only at the substantially thin portion, and the above-mentioned effect is obtained. Can be obtained more reliably.

The synthetic resin sheet is preferably made of a synthetic resin having self-lubricating properties and abrasion resistance as in the rack and pinion type steering device of the third embodiment. As the synthetic resin having, specifically, for example, a polyamide resin, a polyacetal resin, a polyolefin resin or a polyester resin can be mentioned as a preferred example, but other synthetic resins or synthetic resins containing a reinforcing material or a lubricant, etc. It may be.

[0013] In a rack and pinion type steering device according to a fourth aspect of the present invention, in the device according to the first to third aspects, each of the pair of ridges has a center at a center of curvature of an arc-shaped outer peripheral surface, The rack guide base is disposed on the arc-shaped concave surface so as to be located at any angle within a range of 30 ° to 50 ° with respect to a straight line connecting the center in the circumferential direction of the arc-shaped outer peripheral surface.

In the rack and pinion type steering apparatus according to a fifth aspect of the present invention, as in any one of the first to fourth aspects of the invention, the synthetic resin sheet includes a curved sheet portion having a concave stripe formed thereon. And a raised sheet portion integrally formed at the center of the curved sheet portion, and the raised sheet portion is fitted in a hole provided in the rack guide base.

Such a synthetic resin sheet having the raised sheet portion fitted into the hole of the rack guide base does not slip off the rack guide base even when sliding with the rack bar due to the movement of the rack bar. The rack bar can be guided as desired over a long period of time. The raised sheet part is
Although it may be any of a circle, an ellipse, and a polygon,
Preferred examples are circular or elliptical.

In a rack and pinion type steering apparatus according to a sixth aspect of the present invention, in the apparatus according to any one of the first to fifth aspects, the elastic means for elastically biasing the rack guide base toward the rack bar. The rack guide base is slidably contacted with the gear case so as to be able to advance and retreat with respect to the rack bar, and is mounted in the gear case.

As the elastic means, coil springs, disc springs,
Any of a leaf spring, rubber and the like may be used, but a coil spring or a disc spring is preferably used.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, the present invention and examples of its embodiments will be described in more detail with reference to the drawings. The present invention is not limited to these examples.

Referring to FIGS. 1 to 4, a rack and pinion type steering apparatus 1 of this embodiment has a metal gear case 3 having a hollow portion 2 and a gear case 3 having a shaft center X through rolling bearings 4 and 5. A steering shaft 6 rotatably supported in the R direction, a pinion 7 disposed in the hollow portion 2 and provided integrally with a shaft end (pinion shaft) of the steering shaft 6, and meshing with the pinion 7. A metal rack bar 9 having rack teeth 8 formed thereon, and a rack guide means 10 disposed in the hollow portion 2 of the gear case 3 for slidably supporting the rack bar 9 in a direction A orthogonal to the axis X. And a coil spring 12 as elastic means for elastically urging the rack guide base 11 of the rack guide means 10 toward the rack bar 9, that is, in the B direction.

The gear case 3 includes a hollow gear case body 1.
5 and a cover member 16 fixed to an end surface of the gear case main body 15 with screws or the like.
Has a cylindrical portion 18, which penetrates through the gear case main body 15 in the direction A perpendicular to the axis of the steering shaft 6, and which is arranged movably in the direction A perpendicular to the rack bar 9. An arc-shaped outer peripheral surface 19 having a predetermined radius of curvature is provided on the back surface opposite to the surface on which the teeth 8 are formed.

A pinion 7 integrally provided at the shaft end of the steering shaft 6 is attached to the gear case main body 15 of the gear case 3 via the steering shaft 6 and the rolling bearings 4 and 5 in the R direction around the axis X. It is rotatably supported.

The rack guide means 10 is mounted in the cylindrical portion 18 of the gear case main body 15, has an arc-shaped concave surface 21 facing the arc-shaped outer peripheral surface 19 of the rack bar 9, and has a through hole at the center. The metal-made rack guide base 11 having the metal-made rack guide 22 is interposed between the arc-shaped outer peripheral surface 19 of the rack bar 9 and the arc-shaped concave surface 21 of the rack guide base 11. Outer surface 1
And a synthetic resin sheet 24 made of a synthetic resin having self-lubricating properties and abrasion resistance fixed to the arcuate concave surface 21 of the rack guide base 11 and having an arcuate concave surface 23 facing the surface 9.

The rack guide base 11 has, in addition to the through hole 22, a recess 25 communicating with the through hole 22, and a pair of protrusions extending in the moving direction A of the rack bar 9 on the arcuate concave surface 21. The cylindrical outer peripheral surface 31 is fitted to the cylindrical inner peripheral surface 32 of the cylindrical portion 18 so as to be slidable with respect to the rack bar 9 in the reciprocating direction B. Thus, the rack guide base 11 is connected to the rack bar 9.
The gear case 3 is slidably contacted with the gear case 3 so as to be able to advance and retreat.

Each of the pair of ridges 26 and 27 having a width in the angular range of θ ° with respect to the circumferential direction has a center in the circumferential direction whose center of curvature O of the arc-shaped outer peripheral surface 19 of the rack bar 9.
And an arc-like shape of the rack guide base 11 so as to be located at any angle within the range of α = 30 ° to 50 ° with respect to a straight line 36 connecting the center 35 in the circumferential direction of the arc-shaped outer peripheral surface 19. It is arranged on the concave surface 21.

The arcuate concave surface 21 of the rack guide base 11
Have two centers O1 and O2 eccentric to the center of curvature O of the arc-shaped outer peripheral surface 19 of the rack bar 9 and have a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface 19 of the rack bar 9. Consisting of arcuate concave surfaces 37 and 38,
The ridge 26 has an arcuate concave surface 37, and the ridge 27 has an arcuate concave surface 3.
8 are provided respectively.

The synthetic resin sheet 24 has concave ridges 42 and 43 in which the projections 26 and 27 of the rack guide base 11 are fitted into the curved sheet portion 41, and corresponds to the concave ridges 42 and 43. The synthetic resin sheet 24 is in contact with the arcuate outer peripheral surface 19 of the rack bar 9 at the arcuate concave surface 23, that is, in the angle range of θ °.
Are thinner portions 44 and 45 which are adjacent to the portions of the concave ridges 42 and 43 on both sides, and which are thinner than the portions which are not in contact with the arc-shaped outer peripheral surface 19 of the rack bar 9.

The arcuate concave surface 23 of the synthetic resin sheet 24
Like the arcuate concave surface 21, the rack bar 9 has centers O1 and O2 that are eccentric with respect to the center of curvature O of the arcuate outer peripheral surface 19, and is larger than the radius of curvature of the arcuate outer peripheral surface 19 of the rack bar 9. , Are formed of two arcuate concave surfaces 47 and 48 having a radius of curvature smaller than the respective radii of curvature of the arcuate concave surfaces 37 and 38, and the concave streak 42 is formed on the curved sheet portion 41 on the arcuate concave surface 47 side by a concave streak 43. Are provided on the curved sheet portion 41 on the arcuate concave surface 48 side, respectively.

The synthetic resin sheet 24 has concave streaks 42 and 43.
In addition to the curved sheet portion 41 on which the curved sheet portion 41 is formed, a circular raised sheet portion 51 integrally formed at the center of the curved sheet portion 41 is provided. The raised sheet portion 51 is provided on the rack guide base 11. Into the through hole 22 provided.

The curved sheet portion 41 of the synthetic resin sheet 24 may be fixed to the arcuate concave surface 21 of the rack guide base 11 using an adhesive or the like.

The coil spring 12 is compressed and arranged between the rack guide base 11 and the lid member 16 in the recess 25. The thin portions 44 and 45 of the synthetic resin sheet 24 are formed by the elastic force of the coil spring 12. , Is elastically pressed against the arc-shaped outer peripheral surface 19 of the rack bar 9.

In the rack and pinion type steering apparatus 1 described above, the rack guide means 10 is a synthetic resin that slidably contacts the arc-shaped outer peripheral surface 19 of the rack bar 9 in the A direction when the steering shaft 6 rotates in the R direction. Sheet 2
The engagement of the rack teeth 8 with the pinion 7 is ensured by the thin portions 44 and 45 of the 4 and guides the movement of the rack bar 9 in the direction A perpendicular to the axis of the steering shaft 6 due to the engagement. I do.

In the rack-and-pinion type steering apparatus 1, since the thin portions 44 and 45 are located on the synthetic resin sheet 24 in contact with the arc-shaped outer peripheral surface 19 of the rack bar 9, the thin portions 44 and 45 are not affected by a long-term load and an impact load. And 45 can be preferably avoided, so that the rack bar 9 can be smoothly slidably supported for a long period of time.

Further, in the rack-and-pinion type steering device 1, the arc-shaped concave surface 23 of the synthetic resin sheet 24 composed of the two arc-shaped concave surfaces 47 and 48 has a curvature larger than the radius of curvature of the arc-shaped outer peripheral surface 19 of the rack bar 9. Since it has a radius, the contact of the rack bar 9 with the arc-shaped outer peripheral surface 19 only at the substantially thin portions 44 and 45 can be ensured, and the above-described effect can be more reliably obtained.

Rack and pinion type steering device 1
According to this, since the raised sheet portion 51 is fitted into the through hole 22 of the rack guide base 11, the synthetic resin sheet 24
However, even when the rack bar 9 slides with the rack bar 9 due to the movement in the direction A, the rack bar 9 does not slip off the rack guide base 11 and can be guided as desired over a long period of time.

[0035]

According to the present invention, even when a rack guide is formed using a synthetic resin sheet, creep of the synthetic resin sheet can be preferably avoided even under a long-term load and an impact load. And a rack-and-pinion type steering apparatus capable of smoothly supporting the steering wheel over a long period of time.

[Brief description of the drawings]

FIG. 1 is a sectional view of an example of a preferred embodiment of a rack and pinion type steering device of the present invention.

FIG. 2 is a sectional view of the rack guide means of the example shown in FIG.

FIG. 3 is a plan view of the rack guide means of the example shown in FIG.

FIG. 4 is a plan view of the rack guide base of the example shown in FIG.

FIG. 5 is a cross-sectional view of the synthetic resin sheet shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rack-pinion type steering apparatus 3 Gear case 7 Pinion 8 Rack teeth 9 Rack bar 10 Rack guide means 11 Rack guide base 19 Arc-shaped outer peripheral surface 21, 23 Arc-shaped concave surface 24 Synthetic resin sheets 26, 27 Ridges 42, 43 Concave stripes 44 , 45 thin part

Claims (6)

[Claims] A rack bar having a gear case, a pinion rotatably supported by the gear case, rack teeth meshing with the pinion, and having an arc-shaped outer peripheral surface facing the rack teeth; Rack guide means for slidably supporting the bar, the rack guide means being mounted in the gear case and having an arcuate concave surface facing the arcuate outer peripheral surface of the rack bar. The rack guide base is interposed between the arc-shaped outer peripheral surface of the rack bar and the arc-shaped concave surface of the rack guide base, and has an arc-shaped concave surface facing the arc-shaped outer peripheral surface of the rack bar. A synthetic resin sheet fixed to the arcuate concave surface, and the rack guide base has at least a pair of ridges extending in the sliding direction of the rack bar on the arcuate concave surface. The synthetic resin sheet has a concave ridge in which the ridge of the rack guide base is fitted, and the synthetic resin sheet comes into contact with the arc-shaped outer peripheral surface of the rack bar at its arc-shaped concave surface corresponding to the portion of the concave ridge. The synthetic resin sheet at each concave portion is a thin portion which is adjacent to the concave portion on both sides and has a smaller thickness than a portion which is not in contact with the arc-shaped outer peripheral surface of the rack bar. Rack and pinion steering system. 2. The rack-and-pinion steering apparatus according to claim 1, wherein the arc-shaped concave surface of the synthetic resin sheet has a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface of the rack bar. 3. The rack and pinion type steering device according to claim 1, wherein the synthetic resin sheet is made of a synthetic resin having self-lubricating properties and wear resistance. 4. A center of each of the pair of ridges has an angle of 30 ° with respect to a straight line connecting the center of curvature of the arc-shaped outer peripheral surface of the rack bar and the center of the arc-shaped outer peripheral surface in the circumferential direction. 5
The rack and pinion type steering device according to any one of claims 1 to 3, wherein the rack and pinion steering device is arranged on the arcuate concave surface of the rack guide base so as to be located anywhere within 0 °. 5. The synthetic resin sheet has a curved sheet portion having a concave streak and a raised sheet portion integrally formed at a central portion of the curved sheet portion. The rack and pinion type steering device according to any one of claims 1 to 4, wherein the rack and pinion type steering device is fitted in a hole provided in the rack guide base. 6. A rack guide base is provided with elastic means for elastically urging the rack guide base toward the rack bar, and the rack guide base is slidably slidable on the gear case so as to be able to advance and retreat with respect to the rack bar. The rack and pinion type steering device according to any one of claims 1 to 5, wherein the rack and pinion type steering device is mounted in the gear case in contact with the rack case.