JP2004351996A - Rack pinion type steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack pinion type steering system which smoothly moves a rack guide to a rack bar even a gear case and a rack guide base body are formed of aluminum or aluminum alloy. <P>SOLUTION: The rack pinion type steering system 1 is furnished with: the gear case 3 made of aluminum or aluminum alloy having a hollow part 2; a steering shaft 6 supported on the gear case 3 free to rotate through roller bearings 4 and 5; a pinion 7 integrally provided on a shaft end part of the steering shaft 6; the rack bar 9 on which a rack tooth 8 to bite on the pinion 7 is formed; the rack guide 10 arranged in the hollow part 2 of the gear case 3 and to support the rack bar 9 free to slide; and a coil spring 11 to pressurize the rack guide 10 toward the rack bar 9. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to a rack and pinion used in a vehicle such as an automobile, in which a pinion is rotated in conjunction with a rotation operation of a handle, and a rack bar having rack teeth meshing with the pinion is reciprocated to perform steering. The present invention relates to a steering apparatus.
[0002]
[Prior art]
The rack and pinion type steering device is generally arranged in a gear case, a pinion rotatably supported on the gear case via a pinion shaft, a rack bar formed with rack teeth meshing with the pinion, and a gear case. , A rack guide that slidably supports the rack bar, and a coil spring that presses the rack guide toward the rack bar.
[0003]
In such a rack-and-pinion type steering device, forces that move away from each other with the rotation of the pinion shaft at the meshing portion between the rack teeth of the rack bar and the pinion act to bend the rack bar, and the teeth of the rack teeth are bent. Since rattling in the arrangement direction of the strips increases, a tapping sound is generated between the teeth of the rack teeth and the pinion.There is a sliding piece having a small frictional resistance on the side opposite to the pinion shaft with the rack bar interposed. The rack guide is pressed against the pinion shaft side by the pressing force of the coil spring, and the sliding piece slides on the rack bar to reduce the sliding frictional resistance with the rack bar, and the tooth of the rack teeth is reduced. The rattle in the arrangement direction of the strips is suppressed, and the hitting sound at the meshing portion between the rack teeth and the pinion is reduced.
[0004]
[Patent Document 1]
Published Japanese Utility Model Application No. 58-19874 [Patent Document 2]
JP-A-53-47222 [0005]
[Problems to be solved by the invention]
In recent years, in a rack-and-pinion type steering device, a gear case is formed of aluminum or an aluminum alloy because of its light weight, easy processing, and the like, and is arranged in a cylindrical portion of the gear case. The rack guide base holding the sliding piece is also made of aluminum or an aluminum alloy because of its light weight, easy processing and low cost.
[0006]
When the gear case and the rack guide base are made of aluminum or an aluminum alloy, it is necessary to secure the sliding function of the rack guide base in the cylindrical part of the gear case. Although a sliding gap (clearance) of about 20 μm is provided, even when such a sliding gap is provided, the rack may be twisted due to the twisting of the teeth caused by the engagement between the pinion and the rack teeth or the action from the wheels at both ends of the rack bar. When a radial load is applied to the guide, the rack guide base may be strongly pressed against the inner peripheral surface of the cylindrical portion of the gear case. In this state, the rack guide base and the gear case may be pressed together with the pressing force of the coil spring. Between the two, so-called "togane", increases the frictional resistance, eventually causing cohesive wear, Problem hindering the movement of the rack bar direction Kkugaido occurs.
[0007]
In order to solve the above-mentioned problem, a technique of providing a grease groove on a cylindrical outer surface of the rack guide base to lubricate between the rack guide base and the inner peripheral surface of the cylindrical portion of the gear case has also been proposed. In the case of the arc shape, the function of the grease reservoir is mainly used, and it is difficult to efficiently supply and spread the grease to the sliding gap, and after all, the gap between the rack guide body and the inner peripheral surface of the cylindrical portion of the gear case is efficiently formed. No lubrication.
[0008]
The present invention has been made in view of such circumstances, and a purpose thereof is to move a rack guide relative to a rack bar even when a gear case and a rack guide base are formed of aluminum or an aluminum alloy. Is to provide a rack-and-pinion type steering device that can smoothly perform the steering.
[0009]
[Means for Solving the Problems]
A rack and pinion type steering apparatus according to a first aspect of the present invention includes a gear case, a pinion rotatably supported by the gear case, a rack bar having rack teeth meshing with the pinion, and a rack bar. A rack guide movably supported; and a spring pressing the rack guide toward a rack bar, wherein the rack guide is slidably in contact with a cylindrical inner peripheral surface of the gear case. A rack guide base having a surface, and a curved arc-shaped concave surface that slidably abuts the arc-shaped outer peripheral surface of the rack bar to slidably support the rack bar and is fixed to the rack guide base. And a spiral groove having a substantially V-shaped cross section is formed all around the cylindrical outer peripheral surface of the rack guide base, and the spiral groove has a depth of Saga 1 To a 100 [mu] m, a width of 100 to 600μm of the opening, the lubricant is filled in the said spiral grooves.
[0010]
According to the rack and pinion type steering device of the first aspect, the spiral groove having a substantially V-shaped cross section, a depth of 10 to 100 μm, and an opening width of 100 to 600 μm is formed in the cylindrical shape of the rack guide base. Since the spiral groove is formed over the entire outer peripheral surface, in addition to the function of the lubricant reservoir, the spiral groove is formed in a sliding gap between the cylindrical outer peripheral surface of the rack guide base and the cylindrical inner peripheral surface of the gear case. And the spreading function of the lubricant can be exhibited. Therefore, the lubricant is always interposed in the sliding gap, and the teeth generated by the meshing between the pinion and the rack teeth are formed. A radial load is applied to the rack guide by the torsion of the rack bar and the action of the wheels at both ends of the rack bar, and the rack guide base is strongly pressed against the inner peripheral surface side of the gear case. Tomoe " However, since the lubricant is interposed between the two, the rack guide can be smoothly moved with respect to the rack bar without increasing frictional resistance and eventually causing adhesive wear.
[0011]
The sliding plate piece fixed to the rack guide base is a curved sliding piece obtained by molding a synthetic resin such as polyacetal resin, or a substantially elliptical or rectangular shape by punching or cutting a material made of a multilayer material. A sliding piece obtained by obtaining the above-mentioned sliding plate material and bending the sliding plate material into a curved shape can be mentioned as a preferred example. Examples of the multilayer material include a thin steel sheet, a porous sintered metal layer integrally formed on the thin steel sheet, and a porous sintered metal layer impregnated in the porous sintered metal layer and partly. Preferable examples include those having a three-layer structure consisting of a synthetic resin layer formed as a thin layer thereon. Examples of the synthetic resin impregnated in the porous sintered metal layer include polytetrafluoroethylene resin. And a synthetic resin having self-lubricating properties and abrasion resistance, such as a polyacetal resin or an oil-containing polyacetal resin containing a lubricating oil agent.
[0012]
In the rack-and-pinion type steering device according to the second aspect of the present invention, in the device according to the first aspect, the bottom of the spiral groove is formed with a minute uneven surface.
[0013]
According to the rack-and-pinion type steering device of the second aspect, since the retention of the lubricant filled in the spiral groove can be improved, the function of the lubricant reservoir by the spiral groove can be further improved, and the rack The lubricant can be efficiently supplied to the sliding gap between the cylindrical outer peripheral surface of the guide base and the cylindrical inner peripheral surface of the gear case, and the lubricant can be spread.
[0014]
In the rack and pinion type steering apparatus according to the third aspect of the present invention, in the apparatus according to the first or second aspect, the lubricant is grease or a solid lubricant.
[0015]
In the present invention, as the grease, a soap-based grease using soap as a thickener, specifically, calcium soap grease, sodium soap grease, aluminum soap grease, lithium soap grease, and the like are preferably used, and a thickener is preferable. A non-soap grease using an inorganic substance such as benton or fine silica, or an organic substance such as copper phthalocyanine or allyl urea can also be used. A grease using a synthetic oil such as a silicone oil, a diester oil, a fluorocarbon oil or the like as the base oil in addition to the mineral oil-based lubricating oil may be used.
[0016]
As the solid lubricant, graphite, molybdenum disulfide, boron nitride, polytetrafluoroethylene resin, or the like is used alone or in combination.
[0017]
In the rack and pinion type steering device according to the fourth aspect of the present invention, in the device according to any one of the first to third aspects, at least one of the gear case and the rack guide base is formed from aluminum or an aluminum alloy. I have.
[0018]
When at least one of the gear case and the rack guide base is made of aluminum or an aluminum alloy as in the fourth embodiment, a lightweight and easy-to-work rack / pinion type steering device is provided in addition to being inexpensive. it can.
[0019]
In the rack and pinion type steering device according to a fifth aspect of the present invention, in the device according to any one of the first to fourth aspects, at least two annular grooves are formed on the outer peripheral surface of the rack guide base at predetermined intervals. An elastic ring is formed and fitted in the annular groove so as to protrude from the outer peripheral surface of the rack guide base, and the elastic ring is made of a rubber elastic body as in the sixth embodiment of the present invention. O-ring.
[0020]
According to the rack and pinion type steering device of the fifth aspect, a radial load acts on the rack guide due to the twisting of the teeth caused by the meshing between the pinion and the rack teeth and the action of the wheels at both ends of the rack bar, and the rack guide base is formed. It is possible to prevent generation of abnormal noise generated when the gear case is strongly pressed against the inner peripheral surface side.
[0021]
Next, examples of the present invention and its embodiments will be described in more detail with reference to the drawings. Note that the present invention is not limited to these examples.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 5, a rack and pinion type steering device 1 of the present embodiment is rotatably supported by a gear case 3 having a hollow portion 2 and made of aluminum or an aluminum alloy via rolling bearings 4 and 5. Rack bar having a steering shaft 6, a pinion 7 disposed in the hollow portion 2 and integrally provided at a shaft end (pinion shaft) of the steering shaft 6, and rack teeth 8 meshing with the pinion 7. 9, a rack guide 10 disposed in the hollow portion 2 of the gear case 3 and slidably supporting the rack bar 9, and a coil spring 11 for pressing the rack guide 10 toward the rack bar 9. .
[0023]
The gear case 3 has a cylindrical portion 12. The rack bar 9, which penetrates through the gear case 3 in a direction perpendicular to the axis of the steering shaft 6 and is movably arranged in the perpendicular direction, has rack teeth 9. An arc-shaped outer peripheral surface 13 is provided on the back surface side opposite to the surface on which 8 is formed.
[0024]
The rack guide 10 made of aluminum or an aluminum alloy has an arc-shaped concave surface 14, a rack guide base 17 having a recess 15 and a through-hole 16 formed in the center in communication with the recess 15, and a reinforcing portion as a reinforcing portion. Has a hollow cylindrical projection 19 integrally formed, and the projection 19 is fitted into the through-hole 16 and closely seats on the arc-shaped concave surface 14. As described above, a curved sliding plate piece 20 fixed to the rack guide base 17 via the projection 19 is provided.
[0025]
The rack guide base 17 has a sliding gap formed between the cylindrical outer peripheral surface 21 of the aluminum or aluminum alloy, the cylindrical outer peripheral surface 21 of the cylindrical portion 12 of the gear case 3, and the cylindrical inner peripheral surface 22 of the present embodiment. , So that the rack guide 10 can move in a direction perpendicular to the axis of the steering shaft 6.
[0026]
A spiral groove 23 having a substantially V-shaped cross section, a depth D of 10 to 100 μm, and an opening width W of 100 to 600 μm is formed on the outer peripheral surface 21 of the rack guide base 17 over the entire circumference. The spiral groove 23 is filled with grease as a lubricant. The spiral groove 23 may have a depth D of 20 to 40 μm and an opening width W of 200 to 400 μm.
[0027]
The bottom 24 of the spiral groove 23 is formed on a minute uneven surface 25, and the uneven surface 25 retains grease as a lubricant filled in the spiral groove 23 in the spiral groove 23. And the grease can be prevented from flowing out from the spiral groove 23 as much as possible. Therefore, the gap between the cylindrical outer peripheral surface 21 of the rack guide base 17 and the cylindrical inner peripheral surface 22 of the gear case 3 can be reduced. The efficient supply of the lubricant to the sliding gap and the spreading function of the lubricant can be exhibited for a long period of time.
[0028]
The sliding plate piece 20 has an arcuate concave surface 28 composed of two arcuate concave surfaces 26 and 27, and the arcuate concave surfaces 26 and 27 partially cover the arcuate outer peripheral surface 13 of the rack bar 9 as described later. And slidably supports the rack bar 9. The arcuate convex surfaces 29 and 30 of the sliding plate piece 20 which are the surfaces on the back side of the arcuate concave surface 28 composed of the two arcuate concave surfaces 26 and 27 are in close contact with the arcuate concave surface 14.
[0029]
The arc-shaped concave surface 26 is a portion within an angular range α ° (where 0 ° <α ° <90 °) on one side of a center line 31 passing through the center of curvature O1 of the arc-shaped outer peripheral surface 13 of the rack bar 9. In the example, a portion 32 at an angle α1 ° = 40 ° circumscribes the arc-shaped outer peripheral surface 13 of the rack bar 9 and has a center of curvature O2 eccentric with respect to the center of curvature O1 of the arc-shaped outer peripheral surface 13 of the rack bar 9. The arc-shaped concave surface 27 has a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface 13 of the rack bar 9, and the arc-shaped concave surface 27 is a center line passing through the center of curvature O 1 of the arc-shaped outer peripheral surface 13 of the rack bar 9. A portion 33 within the angle range α ° (where 0 ° <α ° <90 °) on the other side of 31, in this example, a portion 33 having an angle α1 ° = 40 ° circumscribes the arc-shaped outer peripheral surface 13 of the rack bar 9. Eccentric with respect to the center of curvature O1 of the arc-shaped outer peripheral surface 13 of the rack bar 9 Having a curvature center O3, a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface 13 of the rack bar 9, and having the same radius of curvature as the radius of curvature of the arc-shaped concave surface 26. The two arc-shaped concave surfaces 26 and 27 are formed symmetrically with respect to the center line 31.
[0030]
The arc-shaped concave surface 14 of the rack guide base 17 is complementary to the shape of the two arc-shaped convex surfaces 29 and 30 so that the two arc-shaped convex surfaces 29 and 30 of the sliding plate piece 20 are in close contact with each other. It is formed with two arcuate concave surfaces 36 and 37 having a shape.
[0031]
The coil spring 11 disposed in the recess 15 has one end in contact with the rack guide base 17 and the other end in contact with the lid member 38 of the gear case 3 in the recess 15, and slides via the rack guide base 17. The plate piece 20 is pressed toward the rack bar 9.
[0032]
In the rack and pinion type steering device 1 described above, the rack guide 10 secures the meshing of the rack teeth 8 with the pinion 7 during the rotation of the steering shaft 6, and furthermore, the rack guide 10 is attached to the axis of the steering shaft 6 due to the meshing. The movement of the rack bar 9 in a direction perpendicular to the direction is guided.
[0033]
According to the rack-and-pinion type steering device 1, the spiral groove 23 having a substantially V-shaped cross section, a depth D of 20 to 40 μm, and an opening width W of 200 to 400 μm is formed in the rack guide base 17. Since the spiral groove 23 is formed over the entire circumference of the outer peripheral surface 21, the spiral groove 23 has a sliding clearance between the outer peripheral surface 21 of the rack guide base 17 and the inner peripheral surface 22 of the gear case 3 in addition to the function of the lubricant reservoir. Grease can be efficiently supplied and spread out to the sliding gap. Therefore, grease is always interposed in the sliding gap, and the torsion of the teeth caused by the meshing between the pinion 7 and the rack teeth 8 is reduced. A radial load is applied to the rack guide 10 by the action of the wheels at both ends of the rack bar 9, and the rack guide base 17 is strongly pressed against the inner peripheral surface 22 side of the gear case 3. Even if the pressing force acts due to the friction between aluminum or aluminum alloy, so-called `` together '', the grease is interposed between them, so that the frictional resistance does not increase, and, consequently, does not cause adhesive wear, The movement of the rack guide 10 with respect to the rack bar 9 can be performed smoothly.
[0034]
FIGS. 6 and 7 show another embodiment of the rack and pinion type steering device 1. In this rack and pinion type steering device 1, the outer periphery of the rack guide base 17 in which the above-mentioned spiral groove 23 is formed. Two annular grooves 39 and 40 are further formed at a predetermined interval on the surface 21, and O-rings 41 and 42 made of rubber elastic material are formed in the annular grooves 39 and 40. It is mounted with a slight protrusion from the part.
[0035]
A rack guide base 17 having O-rings 41 and 42 mounted on the outer peripheral surface 21 is disposed in the hollow portion 2 of the gear case 3 and slidably supports the rack bar 9. Since the O-rings 41 and 42 are interposed between the inner peripheral surface 21 and the inner peripheral surface 22 of the cylindrical portion 12, even if wheel vibrations or the like are transmitted to the rack guide 10, the rack guide 10 does not rattle. Therefore, generation of a tapping sound can be prevented. In addition, even if a force is applied to the rack teeth 8 in a direction perpendicular to the direction in which the rack teeth 8 are moved when the handle is operated, an effect of preventing vertical vibration of the rack guide 10, that is, occurrence of a dance is provided.
[0036]
【The invention's effect】
According to the present invention, even when the gear case and the rack guide base are made of aluminum or an aluminum alloy, the movement of the rack guide with respect to the rack bar can be performed smoothly, and further, the rattle of the rack guide and dance And a rack-and-pinion type steering device in which hitting noise is prevented.
[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 plan view of the rack guide of the example shown in FIG.
FIG. 3 is a side view of the rack guide of the example shown in FIG. 1;
FIG. 4 is a sectional view taken along line IV-IV of the rack guide of the example shown in FIG. 2;
FIG. 5 is an enlarged sectional view of a spiral groove.
FIG. 6 is a sectional view of an example of a preferred embodiment of a rack and pinion type steering device of the present invention using another rack guide.
FIG. 7 is a sectional view showing a rack guide in FIG. 6;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Rack and pinion type steering device 3 Gear case 7 Pinion 8 Rack teeth 9 Rack bar 10 Rack guide 11 Coil spring 17 Rack guide base 21 Outer peripheral surface 23 Helical groove

Claims (6)

A gear case, a pinion rotatably supported by the gear case, a rack bar formed with rack teeth meshing with the pinion, a rack guide slidably supporting the rack bar, and a rack bar A rack guide body having a cylindrical outer peripheral surface slidably in contact with the cylindrical inner peripheral surface of the gear case, and an arc-shaped outer periphery of the rack bar. A curved slide plate piece having an arcuate concave surface slidably in contact with the surface and slidably supporting the rack bar and being fixed to a rack guide base. A spiral groove having a substantially V-shaped cross section is formed on the entire cylindrical outer peripheral surface of the base, and the spiral groove has a depth of 10 to 100 μm and a width of the opening. Is 100 or more A 00Myuemu, rack and pinion type steering apparatus in the spiral groove, characterized in that the lubricant is filled. 2. The rack and pinion type steering apparatus according to claim 1, wherein a portion near the bottom of the spiral groove is formed with a minute uneven surface. The rack and pinion type steering device according to claim 1 or 2, wherein the lubricant is grease or a solid lubricant. The rack and pinion type steering apparatus according to any one of claims 1 to 3, wherein at least one of the gear case and the rack guide base is formed of aluminum or an aluminum alloy. At least two annular grooves are formed on the outer peripheral surface of the rack guide base at predetermined intervals, and an elastic ring is fitted in the annular groove so as to protrude from the outer peripheral surface of the rack guide base. The rack and pinion type steering apparatus according to any one of claims 1 to 4. The rack and pinion type steering device according to claim 5, wherein the elastic ring is an O-ring made of a rubber elastic body.

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