JP5194627B2 - Steering device - Google Patents

Description

The present invention relates to a steering device, and more particularly to a steering device that improves the strength of rack teeth at the stroke end of a rack.

  There is a steering device that operates a steering wheel to rotate a pinion, reciprocally moves a rack that meshes with the pinion, and steers a steered wheel via a tie rod. In such a rack and pinion type steering device, when the rack reaches the stroke end, the rack end fixed to the rack end comes into contact with a stopper fixed to the end of the rack housing, and the rack stops.

  Therefore, when the rack stops at the stroke end, a large thrust acts on the rack teeth at the stroke end meshing with the pinion, and stress concentrates on the rack teeth, resulting in insufficient strength of the rack teeth at the stroke end. There was a thing.

  Patent Document 1 and Patent Document 2 are designed to improve the strength of the rack teeth, but improve the strength of all the rack teeth of the rack equally, and the rack at the stroke end on which a large thrust acts. The tooth strength is not particularly improved.

JP 7-277207 A JP 11-270657 A

  It is an object of the present invention to provide a steering device rack and a steering device in which stress concentration acting on the base of a rack tooth meshing with a pinion at the stroke end of the rack is alleviated, and the number of parts and the manufacturing cost are increased. And

According to a first aspect of the present invention, there is provided a steering apparatus including a rack that meshes with a pinion that rotates by operation of a steering wheel and reciprocates to apply a steering force to a steering gear. The rack is fixed to a housing at a stroke end thereof. A rack end that abuts against the stopper and restricts the rack teeth from being separated from the pinion, and the bottom of the rack teeth that mesh with the pinion at the stroke end of the rack is connected to the rack at the stroke center side. By lowering the tooth bottom of the tooth and making the tooth thickness of the rack tooth base larger than the tooth thickness of the rack tooth base of the stroke center side, the rack end contacts the stopper at the stroke end. in contact, when the rack has been stopped, so as to alleviate the concentration of stress acting on the tooth root of the rack teeth It is a steering apparatus according to claim.

The second invention is a steering apparatus of the first aspect, a plurality of rack teeth that mesh with the pinion at the stroke end of the rack, the tooth bottom is formed so as to gradually decrease toward the stroke end This is a steering device.

  In the steering device rack and the steering device of the present invention, the bottom of the rack tooth that meshes with the pinion at the stroke end of the rack is lower than the bottom of the rack tooth on the stroke center side. Accordingly, the tooth thickness of the rack tooth base at the stroke end side is larger than the tooth thickness of the rack tooth base at the stroke center side. Therefore, stress concentration acting on the base of the rack teeth meshing with the pinion at the stroke end of the rack is alleviated, so that the durability of the rack is improved, the number of parts is not increased, and the increase in manufacturing cost is small.

  FIG. 1 shows a steering apparatus according to an embodiment of the present invention, wherein (1) is an overall perspective view of a column assist type rack and pinion type steering apparatus, and (2) is an overall perspective view of the pinion assist type rack and pinion type steering apparatus.

  The column assist type rack and pinion type power steering apparatus shown in FIG. 1A applies a steering assist force of a motor 102 attached to an intermediate portion of a column 105 to a steering shaft in order to reduce the operation force of the steering wheel 101. ing. Then, the rotation of the steering shaft is transmitted to the intermediate shaft 106, the rack of the rack and pinion type steering gear 103 is reciprocated, and the steering wheel is steered via the tie rod 104.

  The pinion assist type rack and pinion type power steering apparatus shown in FIG. 1 (2) applies the steering assist force of the motor 107 to the pinion shaft that meshes with the rack of the steering gear 103 in order to reduce the operating force of the steering wheel 101. ing. The rack of the steering gear 103 that meshes with the pinion of the pinion shaft is reciprocated to steer the steered wheel via the tie rod 104.

  In such column assist type and pinion assist type rack and pinion type power steering devices, the steering assist force acts on the meshing surface between the rack and the pinion. Therefore, when the rack end comes into contact with the end face of the rack housing at the rack stroke end, a large thrust acts on the rack, and a large stress is applied to the tooth base of the rack tooth surface at the stroke end meshing with the pinion at the rack stroke end. Works.

  2 is a longitudinal sectional view showing a meshing portion between a rack and a pinion of the column assist type rack and pinion type steering device of FIG. 3 is a cross-sectional view taken along line AA of FIG. 2 showing a state where the rack is at the center position of the rack stroke. 4 is a cross-sectional view taken along line AA of FIG. 2 showing a state where the rack is at the end of the rack stroke.

  As shown in FIG. 2, the lower end portion of the pinion shaft 22 is pivotally supported by a ball bearing 23 and a needle bearing 24 on the housing 21 of the steering gear 103. The upper end of the pinion shaft 22 is connected to the intermediate shaft 106 in FIG. 1 (1) via a cardan joint (not shown).

  The rotation of the pinion shaft 22 is transmitted to the rack 31 via the pinion 221, and is connected to the rack 31 via FIG. 1 (1) and the tie rods (steering devices) 104 and 104 of FIGS. Change the direction of the helm.

  In the rolling rack guide, a roller 41 is pressed against an outer periphery 33 on the back side of the rack teeth 32 of the rack 31 by an adjustment cover 42. The roller 41 is rotatably supported on a cylindrical shaft body 43 by a plurality of needle rollers 44. The shaft body 43 is accommodated in the groove 451 of the cylindrical holder 45. The rack guide is not limited to the rolling rack guide of the embodiment of the present invention, and may be a sliding rack guide.

  A guide hole 25 having a circular cross section is formed in the housing 21, and a holder 45 is fitted into the guide hole 25 so as to be slidable in the left-right direction in FIG. The adjustment cover 42 is rotated to appropriately adjust the screwing distance, and the adjustment cover 42 is prevented from loosening with the lock nut 46, so that the holder 45 is pressed against the rack 31 side via the disc spring 47, and the outer periphery 33 of the rack 31. The roller 41 is pressed against the surface. Thereby, the backlash of the meshing part between the pinion 221 and the rack 31 is eliminated, and the rack 31 moves smoothly.

  As shown in FIGS. 3 and 4, a rack end 34 is fixed to the left end of the rack 31, and this rack end 34 is coupled to a tie rod 104 via a ball joint (not shown), and the steering force of the steering wheel 101 is applied to the wheel. To communicate. Although not shown, a rack end 34 shown in FIGS. 3 and 4 is also fixed to the right end of the rack 31 and coupled to the right tie rod 104 via a ball joint.

  As shown in FIG. 4, the rack 31 moves to the right side, and at the stroke end on the right side of the rack 31, the rack end 34 comes into contact with the stopper 26 fixed to the left end of the housing 21. Is restricted from being removed from the pinion 221.

  FIG. 5 shows a single rack 31 according to an embodiment of the present invention. (1) is a plan view of the single rack 31, (2) is a front view of (1), and FIG. 6 is an enlarged cross-sectional view of a portion P in FIG. FIG.

  As shown in FIGS. 5 and 6, two adjacent rack teeth (teeth) 321 and 322 on the right end side (stroke end side) of the rack 31 are tooth bottoms 361 and 362 on the right tooth surfaces 351 and 352 side. However, it is formed lower than the tooth bottoms 363 and 364 on the right tooth surfaces 353 and 354 side of the rack teeth (teeth) 323 and 324 on the stroke center side.

  That is, the tooth bottoms 363 and 364 on the right tooth surfaces 353 and 354 of the rack teeth 323 and 324 on the stroke center side are formed at the same tooth bottom position. The tooth bottom 362 on the right tooth surface 352 side of the rack tooth 322 on the stroke end side with respect to the rack tooth 323 is formed lower than the tooth bottom 363 on the right tooth surface 353 side of the rack tooth 323 on the stroke center side. Further, the tooth bottom 361 on the right tooth surface 351 side of the rack tooth 321 on the stroke end side with respect to the rack tooth 322 is formed lower than the tooth bottom 362 on the right tooth surface 352 side of the left rack tooth 322.

  Accordingly, the tooth thicknesses S1 and S2 of the tooth bases of the two rack teeth 321 and 322 on the stroke end side (right end side) are larger than the tooth thicknesses S3 and S4 of the tooth bases of the rack teeth 323 and 324 on the stroke center side. The tooth root stress that is formed and acts on the tooth root at the stroke end can be relaxed.

  Further, the two rack teeth 326 and 327 adjacent to the left end side (stroke end side) of the rack 31 are opposite to the rack teeth 321 and 322 on the right end side, and the tooth base on the left tooth surface side has a stroke. It is formed lower than the tooth bottom on the left tooth surface side of the rack tooth 325 on the center side. In addition, the bottom of the left tooth surface of the rack tooth 327 on the stroke end side is formed lower than the bottom of the rack tooth 326 on the left tooth surface side.

Therefore, the tooth thickness at the base of the two rack teeth 326 and 327 on the stroke end side (left end side) is
It is formed larger than the tooth thickness of the tooth base of the rack tooth 325 on the stroke center side, and it becomes possible to relieve the tooth root stress acting on the tooth root at the stroke end.

  The rack tooth bottoms except for the rack teeth 321, 322, 326, and 327 on the stroke end side are the same as the tooth bottoms 363 and 364 on the right tooth surfaces 353 and 354 side of the rack teeth 323 and 324 on the stroke center side. It is formed in the tooth bottom position.

  Accordingly, when the steering wheel 101 is operated to rotate the pinion 221 in FIG. 2, the rack 31 moves to the left in FIGS. 5 (1) and 5 (2). When the rack 31 reaches the left stroke end, the rack end 34 on the right side of the rack 31 comes into contact with the stopper 26 fixed to the right end of the housing 21 and the rack 31 stops.

  A large thrust in the direction of the arrow F1 in FIGS. 5 (2) and 6 acts on the teeth of the right tooth surfaces 351 and 352 of the rack teeth 321 and 322 meshing with the pinion 221 at the left stroke end of the rack 31. To do. However, the rack teeth 321 and 322 are formed such that their tooth thicknesses S1 and S2 are larger than the tooth thicknesses S3 and S4 of the rack teeth 323 and 324 at the stroke center side.

  Therefore, the stress concentration acting on the tooth bases of the rack teeth 321 and 322 is alleviated, and the durability of the rack teeth 321 and 322 is improved. Moreover, since the number of parts does not increase, the number of assembling steps is reduced, and the increase in manufacturing cost is small.

  Further, by operating the steering wheel 101 in the reverse direction, the rack 31 moves to the right side in FIGS. 5 (1) and (2), and when the rack 31 reaches the right stroke end, the rack end on the left side of the rack 31 is reached. 34 comes into contact with a stopper 26 fixed to the left end of the housing 21 and the rack 31 stops.

  Therefore, at the stroke end on the right side of the rack 31, a large thrust in the direction of the arrow F2 in FIG. 5 (2) acts on the teeth of the left tooth surfaces of the rack teeth 326 and 327 engaged with the pinion 221. However, the rack teeth 326 and 327 are formed such that the tooth thickness of the tooth base is larger than the tooth thickness of the rack tooth 325 at the stroke center side, and therefore, the stress acting on the tooth base of the rack teeth 326 and 327 The concentration is relaxed, and the durability of the rack teeth 326 and 327 is improved.

  Since the rack 31 of the embodiment of the present invention has a simple shape, it can be easily manufactured not only by non-cutting processing such as cold forging but also by cutting processing such as hobbing and slotter processing. Grinding and polishing are easy.

  In the above-described embodiment, an example in which the present invention is applied to a steering apparatus having an electric power steering apparatus has been described. However, the present invention may be applied to a steering apparatus without an electric power steering apparatus.

1 shows a steering apparatus according to an embodiment of the present invention, wherein (1) is an overall perspective view of a column assist type rack and pinion type steering apparatus, and (2) is an overall perspective view of the pinion assist type rack and pinion type steering apparatus. It is a longitudinal cross-sectional view which shows the meshing part of the rack and pinion of the column assist type | mold rack and pinion type steering device of FIG. It is AA sectional drawing of FIG. 2 which shows the state which has a rack in the center position of a stroke. It is AA sectional drawing of FIG. 2 which shows the state which has a rack in the edge part of a rack stroke. The rack single-piece | unit of the Example of this invention is shown, (1) is a top view of a rack single-piece | unit, (2) is a front view of (1). It is the P section expanded sectional view of Drawing 5 (2).

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Steering wheel 102 Motor 103 Steering gear 104 Tie rod 105 Column 106 Intermediate shaft 107 Motor 21 Housing 22 Pinion shaft 221 Pinion 23 Ball bearing 24 Needle bearing 25 Guide hole 26 Stopper 31 Rack 32 Rack teeth 321, 322, 323, 324 Rack teeth 325 326, 327 Rack teeth 33 Outer periphery 34 Rack end 351, 352, 353, 354 Right tooth surface 361, 362, 363, 364 Tooth bottom 41 Roller 42 Adjust cover 43 Shaft body 44 Needle roller 45 Holder 451 Groove 46 Lock nut 47 Dish Spring

Claims (2)

In a steering device having a rack that meshes with a pinion that rotates by operation of a steering wheel and reciprocates and applies steering force to a steering gear.
The rack has a rack end for restricting the rack teeth from coming off the pinion by abutting a stopper fixed to the housing at the stroke end,
The bottom of the rack tooth that meshes with the pinion at the stroke end of the rack is lower than the bottom of the rack tooth on the stroke center side, and the tooth thickness at the base of the rack tooth is set to the rack tooth tooth on the stroke center side. By making it larger than the original tooth thickness, when the rack end abuts against the stopper at the stroke end and the rack is stopped, the concentration of stress acting on the rack tooth base is alleviated. A steering apparatus characterized by that. The steering apparatus according to claim 1 , wherein
The steering device according to claim 1, wherein a plurality of rack teeth meshing with the pinion at a stroke end of the rack are formed so that a tooth bottom gradually decreases toward the stroke end.

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