JP2012017102A - Rack and pinion steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rack and pinion steering device that reduces the generation of collision noise caused by collision of a rack guide to an inner circumferential surface of a cylindrical part of a gear case and by collision between a rack tooth of a rack bar and a tooth of a pinion as much as possible, and that does not give a sense of discomfort to a driver, even when a load in a radial direction acts on the rack guide.SOLUTION: The rack and pinion steering device S includes: the gear case 22 which has the cylindrical part 20 and a hollow part 21 and is made of an aluminum alloy; a steering shaft 25 which is freely and rotatably supported to the gear case 22 through rolling bearings 23 and 24; the pinion 26 which is arranged in the hollow part 21 and installed integrally with a shaft end of the steering shaft 25; the rack bar 28 which has the rack tooth 27 engaging with the pinion 26; the rack guide 29 which is arranged in the hollow part 21 of the gear case 22 and slides and supports the rack bar 28; a coil spring 30 which pushes the rack guide 29 toward the rack bar 28; and a lid member 32 which blocks an opening of the cylindrical part 20 of the gear case 22.

Description

  The present invention relates to a rack and pinion used in a vehicle such as an automobile, in which a pinion is rotated in conjunction with a rotating 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 type steering device.

  As shown in FIG. 9, this type of rack and pinion type steering apparatus includes a gear case 1, a pinion 3 that is rotatably supported by the gear case 1 via a pinion shaft 2, and rack teeth 4 that mesh with the pinion 3. Formed in the gear case 1, a rack guide 6 that slidably supports the rack bar 5, a coil spring 7 that presses the rack guide 6 toward the rack bar 5, and And a lid member 8 that closes the opening of the gear case 1.

  In such a rack and pinion type steering device, a rack guide 6 made of iron-based sintered metal or synthetic resin is used to smoothly reciprocate the rack bar 5 in conjunction with the rotation operation of the handle.

  The rack guide 6 made of iron-based sintered metal has sufficient mechanical strength with respect to the load from the rack bar 5, but has a large sliding friction resistance with the rack bar 5, thereby reducing the efficiency of the steering system. There is a problem with steering performance.

  The rack guide 6 made of synthetic resin can reduce the sliding frictional resistance with the rack bar 5, but is inferior in mechanical strength and has dimensional variations due to molding shrinkage and the like, and is molded with high dimensional accuracy. In addition, it is difficult to maintain the dimensional accuracy after molding, and further, after being incorporated in the gear case 1, it undergoes thermal expansion and contraction due to the influence of temperature due to temperature rise, thereby causing thermal deformation and creep. There arises a problem that it is difficult to smoothly support the rack bar 5 over a long period of time.

  In view of the above problems, the sliding piece 9 is formed using a self-lubricating synthetic resin or a composite member having a synthetic resin layer, and the sliding piece 9 is shown in FIGS. 10 and 11. A rack guide 6 is proposed in which a rack guide base 10 made of iron-based sintered metal or aluminum alloy is combined with a slide piece 9 and a rack guide base 10 made of iron-based sintered metal or aluminum alloy. Yes.

  The rack guide 6 shown in FIG. 10 and FIG. 11 has been awarded in recent years because it can smoothly reciprocate the rack bar 5 in conjunction with the rotation operation of the handle.

  By the way, in any of the rack guides 6 described above, it is necessary to ensure the sliding function of the rack guide 6 in the cylindrical portion 11 of the gear case 1, and therefore the outer peripheral surface 12 of the rack guide 6 and the inner periphery of the cylindrical portion 11 of the gear case 1. A sliding gap (clearance) of about 20 to 50 μm is provided between the surface 13.

  However, when the ratio H / D between the height H of the rack guide and the outer diameter D of the rack guide is relatively small, the following problems occur due to the sliding gap (clearance). Was confirmed. That is, when a radial load is applied to the rack guide 6 due to tooth twisting caused by the meshing of the pinion 3 and the rack teeth 4 or from the wheels on both ends of the rack bar 5, the rack guide 6 attaches the rack guide 6 to the rack bar. The rack guide 6 collides with the inner peripheral surface 13 of the cylindrical portion 11 of the gear case 1 to generate a collision sound. In addition, due to the large rotation of the rack guide 6, the rack teeth 4 of the rack bar 5 move away from the pinion 3, and the rack guide 6 moves by the gap between the bottom surface 14 of the rack guide 6 and the lid member 8, When a gap is generated between the rack teeth 4 of the rack bar 5 and the tooth surfaces of the pinion 3 and the load direction to the rack guide 6 is reversed, the rack bar 5 is moved by the spring force of the coil spring 7. It is returned to the position, where the teeth of the rack teeth 4 and the pinion 3 of the rack bar 5 is to generate a colliding collision sound, and the like.

  The collision sound generated when the rack guide 6 collides with the inner peripheral surface 13 of the cylindrical portion 11 of the gear case 1 and the collision sound generated when the rack teeth 4 of the rack bar 5 and the teeth of the pinion 3 collide are The driver will be uncomfortable.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide an inner peripheral surface of the cylindrical portion of the gear case of the rack guide even when a radial load is applied to the rack guide. To provide a rack and pinion type steering device that makes it possible to minimize the occurrence of a collision sound caused by a collision and a collision noise caused by a collision between a rack tooth of a rack bar and a pinion tooth, and does not give a driver uncomfortable feeling. It is in.

  The rack and pinion type steering device according to the first aspect of the present invention includes a gear case, a pinion rotatably supported by the gear case, a rack bar formed with rack teeth meshing with the pinion, and a slide for the rack bar. The rack guide includes a rack guide that is movably supported and a spring that presses the rack guide toward the rack bar. The rack guide is slidably brought into contact with the outer peripheral surface of the rack bar. The rack guide has a concave surface that slidably supports and a standing wall portion that faces the concave surface, and the outer peripheral surface of the rack guide is slidably in contact with the cylindrical inner peripheral surface of the gear case. The ratio H / D between the height H of the rack guide and the outer diameter D of the rack guide is 0.6 or more.

  According to the rack and pinion type steering device of the first aspect, the height H of the rack guide and the outer diameter D of the rack guide which are slidably in contact with the cylindrical inner peripheral surface of the gear case on the outer peripheral surface. Since the ratio H / D is 0.6 or more, the rack guide rotates in the radial direction on the rack guide, and the rack guide rotates around the contact portion with the spring that presses the rack guide toward the rack bar (neck Swinging), the rotation angle (swinging angle) can be reduced, so that the occurrence of collision noise can be minimized.

  In addition, since the rack guide rotation angle (swinging angle) can be reduced to reduce the amount of rack guide movement (sinking amount) away from the rack bar, the rack bar rack teeth and pinion teeth The collision sound caused by the collision with the vehicle can be reduced as much as possible, and the driver is not uncomfortable.

  In addition, it was confirmed that the above-mentioned effect hardly occurs when the ratio H / D between the height H of the rack guide and the outer diameter D of the rack guide is smaller than 0.6.

  In a preferred example, the ratio H / D of the height H of the rack guide and the outer diameter D of the rack guide is not less than 0.7 as in the apparatus of the second aspect of the present invention. From the viewpoint of reducing the swing angle), the larger the ratio H / D, the better. However, from the viewpoint of downsizing of the apparatus, etc., preferably, as in the apparatus of the third aspect of the present invention. 2.0 or less, and more preferably 1.5 or less as in the apparatus of the fourth aspect of the present invention.

  In the rack and pinion type steering device according to the fifth aspect of the present invention, in the device according to any one of the first to fourth aspects, each of the standing wall portions of the rack guide passes at least the axis of the rack bar and the rack guide. It extends to a flat portion perpendicular to the sliding direction.

  According to the rack and pinion type steering device of the fifth aspect, it is possible to prevent the rack guide from rotating (swinging) around the contact portion with the spring that presses the rack guide toward the rack bar.

  In the rack and pinion type steering device according to the sixth aspect of the present invention, in the device according to any one of the first to fifth aspects, the rack guide is positioned between both ends of the cylindrical inner peripheral surface of the gear case. .

  According to the rack and pinion type steering device of the sixth aspect, it is possible to further reliably obtain the effect of the specific ratio H / D between the height H of the rack guide and the outer diameter D of the rack guide.

  In the rack and pinion type steering device according to the seventh aspect of the present invention, in the device according to any one of the first to sixth aspects, the rack guide includes a rack guide base having a concave seat at one end, and the rack. And a slide piece fitted to the concave seat of the guide base. The concave face for slidably supporting the rack bar is provided on the slide piece, and the standing wall portion is provided on the rack guide base. It has been.

  According to such a rack and pinion type steering device of the seventh aspect, the sliding piece is fitted to the concave seat of the rack guide base and its pressure resistance is increased, so that the rack bar can be smoothed over a long period of time. The frictional resistance is greatly reduced in sliding with the outer peripheral surface of the rack bar, and the reciprocating movement of the rack bar can be performed smoothly.

  In the rack and pinion type steering device of the eighth aspect of the present invention, in the device of the seventh aspect, the rack guide base is formed of an aluminum alloy or an iron-based sintered metal.

  According to the rack and pinion type steering device of the eighth aspect, in particular, the aluminum alloy is light in weight, easy to process, and inexpensive, so the cost of the rack guide itself is greatly reduced. be able to.

  In the rack and pinion type steering device of the ninth aspect of the present invention, in the device of the seventh or eighth aspect, the sliding piece is a porous metal integrally formed on the thin steel plate and the thin steel plate. It consists of a sintered layer and a synthetic resin layer that is impregnated and coated on the sintered metal layer and has self-lubricating and wear resistance. The synthetic resin layer forms a concave surface that supports the rack bar slidably. ing.

  According to the rack and pinion type steering device of the ninth aspect, the concave surface provided on the sliding piece is formed of a synthetic resin layer having self-lubricating properties and wear resistance. In this sliding, the frictional resistance is greatly reduced, the rack bar can be reciprocated more smoothly, and even if the synthetic resin layer is worn, the porous metal sintered layer is formed on the concave surface. Since the synthetic resin impregnated therein is exposed, the reduction of the sliding frictional resistance is maintained for a long time.

  Examples of the synthetic resin impregnated and coated on the porous metal sintered layer include, for example, a polytetrafluoroethylene resin or a polytetrafluoroethylene resin containing a filler such as lead or polyimide resin, a polyacetal resin, or a lubricating oil. A synthetic resin excellent in self-lubricating property and wear resistance, such as an oil-containing polyacetal resin containing bismuth, can be used.

  In the rack and pinion type steering device of the tenth aspect of the present invention, in the device of the seventh or eighth aspect, the sliding piece slidably supports the convex surface and the rack bar seated on the concave seat of the rack guide base. Each of the concave surfaces is made of a synthetic resin having self-lubricating properties and wear resistance.

  In the rack and pinion type steering device of the tenth aspect, examples of the synthetic resin include a synthetic resin excellent in self-lubricating property and wear resistance, such as a polyacetal resin or an oil-containing polyacetal resin in which a lubricating oil is contained. Can do.

  According to the present invention, even when a radial load is applied to the rack guide, the collision sound caused by the collision of the rack guide gear case with the inner peripheral surface of the cylindrical portion and the collision caused by the collision between the rack teeth of the rack bar and the pinion teeth. It is possible to provide a rack and pinion type steering device that makes it possible to minimize the generation of sound and does not cause discomfort to the driver.

FIG. 1 is a cross-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 cross-sectional view taken along the line III-III of the rack guide of the example shown in FIG. 4 is a cross-sectional view of the example rack guide shown in FIG. 2 taken along line IV-IV. FIG. 5 is a cross-sectional view of another aspect of the rack guide. FIG. 6 is a plan view of another aspect of the rack guide. FIG. 7 is a cross-sectional view of another embodiment of the sliding piece. FIG. 8 is a rear view of the sliding piece shown in FIG. FIG. 9 is a cross-sectional view showing a conventional rack and pinion type steering device. FIG. 10 is a cross-sectional view showing another conventional rack and pinion type steering apparatus. FIG. 11 is a plan view of the prior art rack guide shown in FIG.

  Next, examples of the present invention and embodiments thereof will be described in more detail with reference to the drawings. The present invention is not limited to these examples.

  1 to 4, the rack and pinion type steering device S of the present example is made of an aluminum alloy gear case 22 having a cylindrical portion 20 and a hollow portion 21, and is rotatable to the gear case 22 via rolling bearings 23 and 24. A rack bar 28 having a supported steering shaft 25, a pinion 26 that is disposed in the hollow portion 21 and is provided integrally with a shaft end portion (pinion shaft) of the steering shaft 25, and rack teeth 27 that mesh with the pinion 26. A rack guide 29 that slides and supports the rack bar 28, a coil spring 30 that presses the rack guide 29 toward the rack bar 28, and a cylindrical portion 20 of the gear case 22. And a lid member 32 that closes the opening.

  The rack bar 28 is arranged to pass through the gear case 22 in a direction perpendicular to the axis of the steering shaft 25 and to be movable in the direction perpendicular to the rack bar 28, and is opposite to the surface on which the rack teeth 27 are formed. Has an arcuate outer peripheral surface 34.

  The rack guide 29 includes a rack guide base 35 made of an aluminum alloy and a sliding piece 36.

  The rack guide base 35 has a cylindrical outer peripheral surface 42 that is slidably in contact with a cylindrical inner peripheral surface 41 of the cylindrical portion 20, and an arc-shaped concave seat 43 that is disposed at one end. And standing wall portions 44, 44 arranged opposite to each other across the concave seat 43, and the bottom peripheral edge of the concave seat 43 formed opposite to each other along the concave seat 43. The protrusions 45, 45, a recess 46 disposed at the other end, and a through-hole 47 that is disposed at the other end and communicates with the recess 46 and opens into the concave seat 43. Have.

  A slide comprising a thin steel plate, a porous metal sintered layer deposited integrally on the thin steel plate, and a synthetic resin layer impregnated and coated with the metal sintered layer and having self-lubricating and wear resistance. The moving piece 36 slidably contacts the outer peripheral surface 34 of the rack bar 28 to slidably support the rack bar 28, and has an arcuate concave surface 51 formed of a synthetic resin layer and a reinforcing portion. The front end blocking portion 52 has a hollow cylindrical projection 53 formed integrally therewith, and the projection 53 is fitted into the through-hole 47 so as to be seated closely on the arcuate concave seat 43. In this manner, the rack guide base 35 is fixed to the rack guide base 35 via the protrusion 53.

  The sliding piece 36 fixed to the arcuate concave seat 43 is rotated on the arcuate concave seat 43 by the ridges 45, 45 formed on the bottom periphery of the arcuate concave seat 43 on the bottom side. It is restrained not to.

  The rack guide 29 is located between the annular ends 48 and 49 of the inner peripheral surface 41 of the cylindrical portion 20, and thus the entirety of the rack guide 29 is placed in the cylindrical portion 20 of the gear case 22 and the inner peripheral surface 41 of the cylindrical portion 20. Is provided with a sliding clearance therebetween, one end of the recess 46 of the rack guide base 35 abuts on the rack guide base 35, and the other end is screwed and fixed to the end of the cylindrical portion 20 of the gear case 22, The sliding piece 36 is pressed toward the rack bar 28 via the rack guide base 35 by the coil spring 30 disposed in contact with the lid member 32 that closes the opening of the cylindrical portion 20.

  In the above rack guide 29 having the rack guide base 35 disposed in the cylindrical portion 20 of the gear case 22 while maintaining a sliding gap with the inner peripheral surface 41 of the cylindrical portion 20, the rack guide base 35 Each of the standing wall portions 44, 44 facing each other across the arc-shaped concave seat 43 formed on one end of the rack is attached to the sliding piece 36 fitted to the arc-shaped concave seat 43 of the rack guide 29. It passes through the axis O of the rack bar 28 that is slidably supported, and extends to a portion of the plane A orthogonal to the sliding direction of the rack guide 29. The height H of the rack guide 29 and the rack guide 22 are extended. The ratio H / D with respect to the outer diameter D of the rack guide base 35, in this example, the ratio H / D between the height H of the rack guide base 35 and the outer diameter D of the rack guide base 35 is approximately 0.8.

  The rack guide 29 ensures the meshing of the rack teeth 27 with the pinion 26 during the rotation of the steering shaft 25, and also allows the rack bar 28 to move in a direction perpendicular to the axis of the steering shaft 25 due to the meshing. invite.

  According to the rack and pinion type steering device S, the ratio H / D between the height H of the rack guide base 35 and the outer diameter D of the rack guide base 35 is approximately 0.8, so that the rack guide 29 has a radial direction. The rotation angle (swing angle) of the rack guide 29 is rotated (swinged) with the contact portion with the coil spring 30 that presses the rack guide 29 toward the rack bar 28 as a fulcrum. And the generation of collision noise can be minimized.

  Further, since the rotation angle (swing angle) of the rack guide 29 can be reduced and the movement amount (sinking amount) of the rack guide 29 toward the lid member 32 can be reduced, the rack teeth 27 of the rack bar 28 and The collision sound caused by the collision with the teeth of the pinion 26 can be reduced as much as possible, and the generation of these collision sounds can be reduced as much as possible, so that the driver is not uncomfortable.

  Further, according to the rack and pinion type steering device S, the standing wall portions 44 and 44 of the rack guide base 35 in which the curved sliding piece 36 is fixed to the arcuate concave seat 43 are slid onto the curved sliding piece 36, respectively. Since it extends to the portion of the plane A including the axis O of the rack bar 28 that is movably supported, the contact portion with the coil spring 30 that presses the rack guide 22 toward the rack bar 28 is used as a fulcrum. The rack guide 22 can be prevented from rotating (swinging).

  FIG. 5 shows another embodiment of the curved sliding piece 36. The sliding piece 36 has an arcuate concave surface 63 composed of two arcuate concave surfaces 61 and 62, and is circular. The arc-shaped concave surfaces 61 and 62 partially slidably contact the arc-shaped outer peripheral surface 34 of the rack bar 28 to slidably support the rack bar 28. The arcuate convex surfaces 64 and 65 of the sliding piece 36, which is the back surface of the arcuate concave surface 63 composed of the two arcuate concave surfaces 61 and 62, are in intimate contact with the arcuate concave seat 43 of the rack guide base 35. ing.

  The arc-shaped concave surface 61 is a portion within an angle range α ° (where 0 ° <α ° <90 °) on one side of a center line 66 passing through the center of curvature O of the arc-shaped outer peripheral surface 34 of the rack bar 28. In this example, the center of curvature circumscribing the arc-shaped outer peripheral surface 34 of the rack bar 28 at a portion 67 having an angle α1 ° = 40 ° and decentering with respect to the center of curvature O of the arc-shaped outer peripheral surface 34 of the rack bar 28. The arc-shaped concave surface 62 has an arcuate concave surface having a radius of curvature larger than the radius of curvature of the arc-shaped outer peripheral surface 34 of the rack bar 28, and the arc-shaped concave surface 62 corresponds to the arc-shaped outer peripheral surface 34 of the rack bar 28. The rack bar 28 is located at a position 68 within the angle range α ° (where 0 ° <α ° <90 °) on the other side of the center line 66 passing through the center of curvature O. In this example, the portion 68 has an angle α1 ° = 40 °. Circumscribing the arc-shaped outer peripheral surface 34 of the rack bar 28 and arc-shaped outer peripheral surface of the rack bar 28 4 has a curvature center O2 that is eccentric with respect to the curvature center O of 4, and a curvature radius that is larger than the curvature radius of the arc-shaped outer peripheral surface 34 of the rack bar 28, and is the same as the curvature radius of the arc-shaped concave surface 61. The arcuate concave surface having a radius is formed, and the two arcuate concave surfaces 61 and 62 are formed symmetrically with respect to the center line 66.

  Thus, the sliding piece 36 having the arc-shaped concave surface 63 composed of the two arc-shaped concave surfaces 61 and 62 has a linear or narrow belt-like contact with the sliding contact with the arc-shaped outer peripheral surface 34 of the rack bar 28. The sliding frictional resistance with the rack bar 28 can be further reduced.

  FIG. 6 shows another embodiment of the curved sliding piece 36, in which the sliding piece 36 is formed in a strip shape. The strip-shaped sliding piece 36 is composed of a thin steel plate, a porous metal sintered layer integrally formed on the thin steel plate, and a multilayer comprising a synthetic resin layer impregnated and coated on the metal sintered layer. In the case of forming with a material, it is effective in terms of material yield.

  7 and 8 show a synthetic resin in which each of a convex surface 71 seated on the concave seat 43 of the rack guide base 35 and an arc-shaped concave surface 72 that slidably supports the rack bar 28 has self-lubricating properties and wear resistance. The curved sliding piece 36 is formed by defining a rectangular hollow portion 73 on the convex surface 71 of the sliding piece 36, and the opposing flat portions 74 and 74 and the flat portions 74 and 74. An engaging protrusion 76 having convex curved surface portions 75 and 75 facing each other is integrally formed. In the rack guide 29 using the sliding piece 36, the rack guide base 35 is provided with a through hole having a shape complementary to the engagement protrusion 76.

  Also in the curved sliding piece 36 shown in FIG. 6, FIG. 7 and FIG. 8, the arc-shaped concave surfaces 51 and 72 are arc-shaped concave surfaces comprising the two arc-shaped concave surfaces 61 and 62 shown in FIG. It is good also as 63. Further, in the above preferred example, each of the standing wall portions 44 and 44 is extended to the portion of the plane A, but instead, each of the standing wall portions 44 and 44 may be extended beyond the portion of the plane A. Good.

S Rack and pinion type steering device 22 Gear case 26 Pinion 27 Rack teeth 28 Rack bar 29 Rack guide 30 Coil spring 41 Inner peripheral surface 42 Outer peripheral surface 44 Standing wall portions 51, 63, 72 Concave surface

Claims (10)

  A gear case, a pinion rotatably supported by the gear case, a rack bar formed with rack teeth that mesh with the pinion, a rack guide that slidably supports the rack bar, and the rack guide The rack guide is opposed to the concave surface that slidably contacts the outer peripheral surface of the rack bar and slidably supports the rack bar, with the concave surface interposed therebetween. And the outer peripheral surface of the rack guide is slidably in contact with the cylindrical inner peripheral surface of the gear case. The height H of the rack guide and the outer diameter D of the rack guide The ratio H / D of the rack and pinion type steering device is 0.6 or more.   The rack and pinion steering device according to claim 1, wherein the ratio H / D is 0.7 or more.   The rack and pinion type steering device according to claim 1 or 2, wherein the ratio H / D is 2.0 or less.   The rack and pinion type steering device according to any one of claims 1 to 3, wherein the ratio H / D is 1.5 or less.   The rack according to any one of claims 1 to 4, wherein each of the standing wall portions of the rack guide is extended to at least a plane portion that passes through at least the axis of the rack bar and is orthogonal to the sliding direction of the rack guide. Pinion type steering device.   The rack and pinion type steering device according to any one of claims 1 to 5, wherein the rack guide is positioned between both ends of the cylindrical inner peripheral surface of the gear case.   The rack guide includes a rack guide base having a concave seat at one end, and a sliding piece fitted to the concave seat of the rack guide base, and a concave surface that slidably supports the rack bar. The rack and pinion type steering apparatus according to any one of claims 1 to 6, wherein the rack is provided on the sliding piece, and the standing wall is provided on the rack guide base.   The rack and pinion type steering device according to claim 7, wherein the rack guide base is made of an aluminum alloy or an iron-based sintered metal.   The sliding piece includes a thin steel plate, a porous metal sintered layer integrally formed on the thin steel plate, and a synthetic resin that is impregnated and coated with the metal sintered layer and has self-lubricity and wear resistance. The rack and pinion steering device according to claim 7 or 8, wherein the synthetic resin layer is formed with a concave surface that slidably supports the rack bar.   9. The sliding piece according to claim 7 or 8, wherein each of the convex surface seated on the concave seat of the rack guide base and the concave surface slidably supporting the rack bar is made of a synthetic resin having self-lubricating properties and wear resistance. Rack and pinion type steering device.

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