JP2006123643A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To suppress deflection of a rack shaft on the supporting side by a support yoke without increasing the sliding resistance of the rack shaft, and prevent the occurrence of the trouble due to the deflection. <P>SOLUTION: In a rack and pinion type steering device, a rack shaft 1 equipped with rack teeth 11 meshing with a pinion 21 rotating according to the steering is supported inside a cylindrical rack housing 10 at two points by a rack bush 24 internally held at the end part of the side separating from the forming area of the rack teeth 11 and a support yoke 23 elastically connected to the back surface of the forming area of the rack teeth 11. A stopper ring 3 which is opposed to the outer peripheral surface of the rack shaft 1 with a predetermined gap, is not contacted in usual time, and contacted when a large deflection is generated is internally held on the end part of the rack housing 10 on the side near the forming area of the rack teeth 11. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rack and pinion type steering apparatus configured to convert a rotation of a pinion according to an operation of a steering member into a movement in the axial direction of a rack shaft meshing with the pinion to perform steering, and more particularly Relates to a support structure for supporting the rack shaft inside a cylindrical housing.

  A rack and pinion type steering device that is widely adopted as a type of vehicle steering device is a rack shaft that is supported inside a cylindrical housing extending in the left-right direction of a vehicle body so as to be movable in the axial direction. And a pinion coupled to a steering member such as a steering wheel and meshing with a rack tooth provided in the middle of the rack shaft, and the rotation of the pinion linked to the operation of the steering member for steering is A structure that converts this movement into a long direction and transmits this movement to the left and right steering wheels (generally the left and right front wheels) connected to the opposite ends of the rack shaft via separate tie rods. It has become.

The support of the rack shaft inside the housing is generally a support yoke that elastically contacts the rack shaft at the back of the rack tooth formation area and applies a predetermined preload to the meshing portion of the rack teeth and the pinion. This is achieved by two-point support by a rack bush fitted to the end of the housing on the side away from the elastic contact position of the support yoke (see, for example, Patent Documents 1 and 2).
Japanese Utility Model Publication No. 57-133470 JP-A-8-169350

  In such a rack and pinion type steering device, the movement of the rack shaft for steering is deflected in various directions under the action of the road surface reaction force applied to the steering wheel via each separate tie rod. As a result, the sliding resistance between the rack bush and the support yoke that supports the rack shaft at two points as described above is large, and the steering feeling deteriorates due to fluctuation depending on the direction of bending. is there.

  In order to solve this problem, conventionally, on the support side by the rack bush, as disclosed in Patent Documents 1 and 2, the rack bush mounting structure and shape have been devised to achieve a predetermined improvement effect. Is obtained.

  On the other hand, on the support side by the support yoke, the sliding force can be reduced by weakening the spring force of the push spring of the support yoke and reducing the elastic contact force to the rack shaft. The preload at the meshing part between the pinion and the pinion is insufficient, the meshing gap is generated due to the influence of the deflection of the rack shaft, and an unpleasant rattling noise due to the collision between the rack tooth and the pinion occurs.

  In addition, some rack and pinion type steering devices are provided with rack bushes on the support side by the support yoke, and a three-point support structure using rack bushes on both sides and a support yoke between them is employed. This support structure has a problem that preloading to the meshing portion by the support yoke is hindered by the restraint of the rack shaft by the rack bushes on both sides, and is not a preferable support structure.

  The present invention has been made in view of such circumstances, and the bending of the rack shaft on the support side by the support yoke is suppressed without increasing the sliding resistance of the rack shaft, and the occurrence of defects due to the bending is generated. An object of the present invention is to provide a rack and pinion type steering device that can prevent the above-mentioned problem.

  A steering device according to a first aspect of the present invention includes a rack shaft provided with rack teeth meshing with a pinion that rotates according to steering, inside a cylindrical housing, on a side away from the rack tooth formation region. In a rack and pinion type steering device that is supported at two points so as to be movable in the axial direction by means of a rack bush that is internally fitted and held at the end and a support yoke that elastically contacts the back surface of the forming area. A stopper ring is provided which is fitted and held at an end portion on the side close to the rack tooth forming area and which is opposed to the outer peripheral surface of the rack shaft with a predetermined gap.

  The steering device according to a second aspect of the present invention is characterized in that the stopper ring according to the first aspect includes a relief portion that is thinner than the other portion, facing the rack tooth formation region.

  In the steering apparatus according to the first aspect of the present invention, the stopper ring is fitted and held at the end of the cylindrical housing that supports the rack shaft, on the side close to the rack tooth formation area, and is fixed to the outer peripheral surface of the rack shaft. Because of the gap, the excessive deflection that occurs on the rack shaft on the support side by the support yoke is limited by the contact with the stopper ring, preventing problems such as rattling noises from occurring. In addition, the stopper ring does not slidably contact the rack shaft that moves with a small amount of bending, and there is no possibility of increasing the sliding resistance.

  In the steering device according to the second aspect of the present invention, since the circumferential portion of the stopper ring facing the rack tooth formation area of the rack shaft is provided with a relief portion that is thinner than the other portions, the rack shaft is bent. The present invention is excellent in that the possibility of contact with the stopper ring occurring in the rack tooth formation area is mitigated, and damage to the stopper ring due to sliding contact with the edge portion of the rack tooth can be prevented in advance. Has an effect.

  Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof. FIG. 1 is a front sectional view showing a configuration of a main part of a steering device according to the present invention. The rotation of a pinion shaft 2 that rotates about an axis in response to an operation of a steering member such as a steering wheel is shown in FIG. The rack shaft 1 is configured as a rack and pinion type steering device that converts the movement of the rack shaft 1 in the axial length direction into steering.

  The rack shaft 1 is supported so as to be movable in the axial length direction inside a cylindrical rack housing 10 extending in the left-right direction of a vehicle body (not shown). A pinion housing 20 having a short cylindrical shape is connected in the vicinity of one end of the rack housing 10, and the pinion housing 20 rotates around an axis intersecting with the rack shaft 1. The pinion shaft 2 is supported freely. Rack teeth 11 are formed on the outer surface of the middle part of the rack shaft 1 over a predetermined length range on both sides of the intersection with the pinion shaft 2, and the rack teeth 11 are formed in the lower half of the pinion shaft 2. Are meshed with a pinion 21 formed integrally with each other.

  Both end portions of the rack shaft 1 are projected to the outside on both sides of the rack housing 10 by appropriate lengths, and these projecting ends are for steering on both the left and right sides (not shown) via separate ball joints 12 and 12 and tie rods 13 and 13, respectively. Connected to the wheels. Further, the upper part of the pinion shaft 2 protrudes to an appropriate length outside the upper side of the pinion housing 20, and this protruding end is connected to a steering wheel 22 schematically shown in the drawing.

  The rack shaft 1 inside the rack housing 10 is separated from the support yoke 23 which is elastically contacted from the surface opposite to the side where the rack teeth 11 are formed (the front side in the figure) at the meshing portion with the pinion 21, and away from the elastic contact position. It is supported at two points by a cylindrical rack bush 24 fitted and fixed to one end of the side rack housing 10. The rack bush 24 is a cylinder having a plurality of protrusions extending in the axial direction on the outer peripheral surface of a resin material having a low friction coefficient, such as polyester elastomer, as disclosed in Japanese Utility Model Laid-Open No. 4-135875 by the applicant of the present application. It is molded into a shape, and the top of each protrusion is fitted and held so that it abuts the inner peripheral surface of the fitting hole provided in the rack housing 10, and the rack shaft 1 inserted and supported on the inside slides smoothly. In addition to guiding, bending of the rack shaft 1 generated as described later is allowed by elastic deformation of the ridges.

  On the other hand, a stopper ring 3 which is a feature of the present invention is fitted and fixed to the other end of the rack housing 10 on the side close to the elastic contact position of the support yoke 23. 2 is an enlarged cross-sectional view in the vicinity of the fitting position of the stopper ring 3, and FIG. 3 is a cross-sectional view taken along line III-III in FIG.

  The stopper ring 3 is a short cylinder formed of a resin material having a low coefficient of friction similar to that of the rack bush 24, and is fitted and fitted coaxially into a fitting hole provided at the same side end of the rack housing 10. Has been. Unlike the rack bush 24, the stopper ring 3 has an inner diameter that is appropriately larger than the outer diameter of the rack shaft 1. As shown in FIG. 2, the stopper ring 3 is inserted into the stopper ring 3. A predetermined gap G is secured between the outer peripheral surface and the outer peripheral surface.

  Further, as shown in FIG. 3, the stopper ring 3 is provided with a relief portion 30 having an inner diameter larger than that of the other portion over a predetermined angular range. The stopper ring 3 is formed by the rack teeth 11 on the outer surface of the rack shaft 1. It is positioned in the circumferential direction so that the escape portion 30 is aligned with the formation area, and is fitted and fixed to the rack housing 10. For such positioning, for example, a convex portion 31 is provided at one location on the outer peripheral surface of the stopper ring 3 and a concave portion 14 is provided at one location on the same side end surface of the rack housing 10, which are shown in FIG. Thus, it can be realized before the rack shaft 1 is assembled by means such as mutual engagement.

  In the rack and pinion type steering apparatus configured as described above, the pinion shaft 2 and the pinion 21 integrally formed therewith rotate around the axis in accordance with the rotation operation of the steering wheel 22 for steering. The rotation of the pinion shaft 2 is converted into movement in the axial direction of the rack shaft 1 at the meshing portion of the pinion 21 and the rack teeth 11, and the rack shaft 1 is supported at two points by the support yoke 23 and the rack bush 24. This movement is transmitted to the left and right steering wheels via the ball joints 12 and 12 and the tie rods 13 and 13, and these wheels are operated in the direction of operation of the steering wheel 22. Steer according to the amount.

  At this time, the road surface reaction force applied to the steering wheel acts on both ends of the rack shaft 1 via the respective tie rods 13 and 13, and these tie rods 13 and 13 are connected to the respective ball joints 12 and 13. Since the rack 12 can be tilted in various directions with the axis 12 as a pivot, the above-described movement of the rack shaft 1 is caused by the action of the road surface reaction force applied from various directions with bending in the direction of action.

  Here, as described above, the rack bush 24 supporting one side of the rack shaft 1 stably supports the rack shaft 1 which is bent in various directions while allowing the bending, and smoothly slides the guide. Is possible. On the other hand, the other side of the rack shaft 1 is supported while being pressed against the pinion 21 by the support yoke 23. In this support portion, the deflection of the rack shaft 1 other than the pressing direction cannot be sufficiently suppressed. Due to the influence of this bending, a problem occurs that a meshing gap is generated between the pinion 21 and the rack teeth 11 to generate a rattling sound.

  The steering device according to the present invention includes a stopper ring 3 fitted and fixed to an end of the rack housing 10 on the support yoke 23 side. The stopper ring 3 has a gap G on the outer peripheral surface of the rack shaft 1. It is facing away. Therefore, when a deflection occurs on the same side of the rack shaft 1, the rack shaft 1 comes into contact with the inner surface of the stopper ring 3 when the magnitude of the deflection reaches the gap G. 1 is suppressed.

  The size of the gap G between the stopper ring 3 and the rack shaft 1 is set in accordance with the amount of bending with a slight influence on the meshing state between the pinion 21 and the rack teeth 11, It is possible to effectively prevent the occurrence of rattling noise associated with excessive deflection of the rack shaft 1. On the other hand, a gap G is secured between the stopper ring 3 and the rack shaft 1 over the entire circumference, and the stopper ring 3 is a rack that moves with a degree of bending assumed during normal steering. Since it does not slide on the shaft 1, the rack shaft 1 can slide smoothly under a small sliding resistance, and a good steering feeling can be obtained.

  The stopper ring 3 has a relief portion 30 facing the formation region of the rack teeth 11 on the outer periphery of the rack shaft 1, and the relief portion 30 is bent toward the rack shaft 11 on the side where the rack teeth 11 are formed. When this occurs, the rack teeth 11 are prevented from coming into contact with the edge portion. Thereby, it becomes possible to prevent the stopper ring 3 from being damaged by the sliding contact of the edge portion. Note that the deflection of the rack shaft 1 toward the side where the rack teeth 11 are formed is a deflection in the direction of reducing the meshing gap between the rack teeth 11 and the pinion 21 and does not involve the generation of rattling noise.

  In the above embodiment, the steering device is described in which the steering is performed only by the operating force applied to the steering wheel 22 by the driver, but the hydraulic power steering device that assists the steering by the hydraulic pressure generated by the hydraulic cylinder, Needless to say, the present invention is also applicable to an electric power steering device that assists steering by the generated force of the electric motor.

It is a front sectional view showing the composition of the important section of the steering device concerning the present invention. It is an expanded sectional view near the fitting position of the stopper ring. FIG. 3 is a transverse sectional view taken along line III-III in FIG. 2.

Explanation of symbols

1 Rack shaft 2 Pinion shaft 3 Stopper ring
10 Rack housing (housing)
11 rack teeth
21 Pinion
23 Support yoke
24 rack bush
30 relief

Claims (2)

A rack shaft having rack teeth meshing with a pinion that rotates in response to steering, a rack bush that is internally fitted and held inside the cylindrical housing at the end on the side away from the rack tooth formation area, In the rack-and-pinion type steering device that is supported at two points so as to be movable in the axial length direction by a support yoke that elastically contacts the back surface of the formation area,
A steering apparatus comprising: a stopper ring that is fitted and held at an end portion of the housing close to the rack tooth formation area and that is opposed to the outer peripheral surface of the rack shaft with a predetermined gap.   2. The steering device according to claim 1, wherein the stopper ring includes an escape portion facing an area where the rack teeth are formed and having an inner diameter larger than that of the other portion.

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