JP2014227028A - Vehicle steering device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicle steering device which prevents adherence of grease to stably supply the grease to a slide contact surface with a rack shaft and thereby enables the rack shaft to smoothly slide for a long period and inhibits the occurence of abnormal noise.SOLUTION: A vehicle steering device includes: a pinion shaft; a rack shaft 3 which meshes with the pinion shaft; a housing 4 which stores the rack shaft 3; and a rack bush 6 which is disposed between the rack shaft 6 and the housing 4 and slidably supports the rack shaft 3 on the housing 4. An inner peripheral surface of the rack bush 6 includes a first groove part 62a which extends from one side to the other side in an axial direction on a slide contact surface 62, which slidably contacts with the rack shaft 3, to be formed into a spiral shape, and a viscous fluid is enclosed in the first groove part 62a.

Description

  The present invention relates to a vehicle steering apparatus.

  2. Description of the Related Art Conventionally, a vehicle steering apparatus includes a rack and pinion type that converts rotation of a pinion shaft accompanying a steering operation into reciprocating movement of the rack shaft by engaging a pinion shaft and a rack shaft. The rack shaft of such a rack and pinion type vehicle steering device is supported by a rack bush provided between the rack shaft and the housing so as to be slidable in the axial direction.

  By the way, in the running state of the vehicle, the so-called stick-slip phenomenon in which the rack shaft repeats sliding and catching may occur due to the vibration in the axial direction generated in the rack bush, which may cause abnormal noise. Are known. For this reason, a lubricant such as grease is arranged between the rack bush and the rack shaft so that the rack shaft slides smoothly and the occurrence of abnormal noise is suppressed by preventing the grease from running out. .

  For example, Patent Document 1 discloses a configuration in which a plurality of dimple holes are provided on an inner peripheral surface of a rack bush that is in sliding contact with a rack shaft. In other words, with this configuration, grease can be held in the dimple hole and grease can be supplied to the sliding contact surface with the rack shaft, so that the rack shaft can slide smoothly and the occurrence of grease breakage can be prevented. The occurrence of abnormal noise can be suppressed.

JP 2003-322165 A

  However, since the grease is always held at the same place in the above dimple hole, the grease may be fixed in the dimple hole in a severe environment or for a long period of use. The grease fixed in the dimple hole is not supplied to the sliding contact surface with the rack shaft. As a result, there is a problem that the grease runs out. In this respect, there is still room for improvement.

  The present invention has been made to solve the above problems, and the problem to be solved by the present invention is to prevent the grease from sticking and stably supply the grease to the sliding contact surface with the rack shaft. Accordingly, an object of the present invention is to provide a vehicle steering apparatus that can smoothly slide a rack shaft over a long period of time and can suppress the generation of abnormal noise.

  According to a first aspect of the present invention, a pinion shaft, a rack shaft that meshes with the pinion shaft, a housing that houses the rack shaft, and the rack shaft and the housing are interposed between the rack shaft and the rack shaft. In a vehicle steering apparatus including a rack bush that is slidably supported on a housing, an inner peripheral surface of the rack bush extends in a spiral manner from one axial direction to the other on a sliding contact surface that is in sliding contact with the rack shaft. The first groove is formed, and viscous fluid is sealed in the first groove.

  According to the first aspect of the invention configured as described above, when the rack shaft supported by the rack bush slides in the axial direction by the steering operation, the grease that is the viscous fluid enclosed in the first groove is the first. While moving spirally along the groove, grease is supplied to the sliding contact surface with the rack shaft. The grease sealed in the first groove portion moves in the first groove portion as the rack shaft and the rack bush slide, so that the grease does not stay in a specific place, so that the grease is fixed in the first groove portion. Can be suppressed. Accordingly, the grease can be stably supplied to the sliding contact surface with the rack shaft as the grease capable of supplying all the grease sealed in the first groove portion.

  The invention according to claim 2 is the vehicle steering apparatus according to claim 1, wherein the rack bushing further includes a second groove portion formed in an axial direction connecting both ends of the first groove portion. Features.

  According to the invention of claim 2 configured as described above, since both ends of the first groove portion are connected by the second groove portion formed in the axial direction, sliding between the rack shaft and the rack bush causes The grease that moves along the one groove and reaches one end is returned to the other end via the second groove. As described above, since the grease is prevented from flowing out by circulating the grease, the grease can be held for a long period of time and stably supplied to the sliding contact surface.

  According to the present invention, there is provided a vehicle steering apparatus capable of smoothly sliding a rack shaft over a long period of time and suppressing occurrence of abnormal noise by preventing grease from sticking and stably supplying grease. Can be provided.

1 is a cross-sectional view showing a vehicle steering apparatus according to an embodiment of the present invention. It is a principal part expanded sectional view which shows the steering apparatus for vehicles which concerns on embodiment of this invention. It is a perspective view which shows the rack bush of FIG. It is an expanded sectional view by the III-III line of FIG. It is a side view which shows the external appearance of the rack bush of FIG. It is sectional drawing by the VV line of FIG.

Hereinafter, a vehicle steering apparatus according to an embodiment of the present invention will be described with reference to the drawings.
As shown in FIGS. 1 and 2, the vehicle steering apparatus of the present embodiment includes a pinion shaft 2, a rack shaft 3 that meshes with the pinion shaft 2, and a housing 4 that houses the rack shaft 3. It is configured as a so-called rack and pinion type vehicle steering device that converts the rotation of the pinion shaft 2 in response to the above operation into the reciprocating motion of the rack shaft 3.

  The housing 4 is formed in a substantially cylindrical shape, and the rack shaft 3 is inserted into the housing 4 along the axis. The rack shaft 3 is housed in a housing 4 and is supported by rack bushes 5 and 6 so as to be slidable in the axial direction in the vicinity of both ends thereof.

  As shown in FIG. 3, the rack bush 6 is made of a synthetic resin and has a cylindrical main body 61 and an engagement protrusion 61 e that protrudes in a bowl shape at one end of the main body 61. In addition, a U-shaped slit 61 </ b> S that opens at one end side in the axial length direction is provided in a part of the rack bush 6 in the circumferential direction.

  In the slit 61S, when the outer diameter of the rack shaft (not shown) is expanded due to thermal expansion, the rack bush 6 is elastically deformed so that the slit 61S is narrowed accordingly. When the rack shaft returns to the original outer diameter, the shape of the rack bush 6 also returns to the original shape, and the rack shaft can be supported again without a gap.

  As shown in FIG. 4, air is removed between the outer peripheral surface of the rack bush 6 between a region 61 a that is in wide contact with the inner peripheral surface 4 b of the housing 4 in the circumferential direction and the inner peripheral surface 4 b of the housing 4. For this reason, regions 61b that are in contact with the inner peripheral surface 4b of the housing 4 only in a narrow range are formed alternately.

  In this region 61a, an engaging projection 61e having a quadrangular cross-sectional shape for positioning and fixing to the housing 4 is projected at one end in the axial direction in the circumferential direction, and a portion excluding the projected position Is formed with a serration 61f that is fitted to the inner peripheral surface 4b of the housing 4 with a tightening margin. As a result, when the rack bush 6 is fitted to the housing 4, the interference between the two is absorbed by the elastic deformation of the serration 61f, and the inner diameter of the rack bush 6 is not distorted.

  In addition, the region 61b is provided with a triangular section ridge portion 61j extending from one end in the axial length direction to the vicinity of the other end at the central portion in the width direction of the flat surface 61i that is cut out in the axial length direction. Thus, when the rack bush 6 is interposed between the housing 4 and the rack shaft 3, the protrusion 61j comes into pressure contact with the inner peripheral surface of the housing 4, and airflow gaps are formed on both sides thereof. It is supposed to be formed. Further, the gap also serves to absorb outward deformation generated in the rack bush 6. In addition, about the cross-sectional shape of this protrusion part 61j, not only the illustrated triangle but square shape, a semi-column shape, etc. may be sufficient.

  As shown in FIG. 5, the end surface of the protrusion 61j on the other end side of the rack bush 6 is a tapered surface 61k that decreases in height toward the inner back side. In the state where the rack bush 6 is fixed to the housing 4, each protrusion 61j presses against the inner peripheral surface of the housing 4 at the center of the region 61b to increase the rigidity of the region 61b.

  As shown in FIG. 6, a sliding contact surface 62 that is in sliding contact with the rack shaft 3 is formed on the inner peripheral surface of the rack bush 6. The sliding contact surface 62 has an inner diameter substantially equal to the diameter of the rack shaft 3. Further, on the inner peripheral surface of the rack bush 6, taper surfaces 61c and 61d having inner diameters slightly larger than the diameter of the rack shaft 3 toward the end side are formed on both end sides, respectively.

  Note that the end surface of the engagement protrusion 61e on the other end side of the rack bush 6 is a tapered surface 61g that decreases its height toward the inner back side in order to facilitate the insertion into the housing 4, and other than the serration 61f. The end side also has a tapered surface 61h that reduces its height toward the inner back side.

  The sliding contact surface 62 is formed with a first groove 62a that spirals from one axial direction to the other, and a second groove 62b that is formed in the axial direction connecting both ends of the first groove 62a. Has been. The first groove 62a is filled with grease, which is a viscous fluid.

  The inner peripheral surface 4b of the housing 4 has a concave mounting surface 4a having substantially the same dimensions as the outer shape of the main body 61, and a mounting surface for engaging with the engaging protrusion 61e in order to mount the rack bush 6. An annular groove 4b provided on the outer side of 4a and a tapered surface 4c which is provided in a step portion connecting the mounting surface 4a and the annular groove 4b and expands toward the outside are provided.

  The rack bush 6 is inserted from the end of the housing 4 so as to fit the serration 61f into the inner peripheral surface 4b of the housing 4, and when the engaging projection 61e is engaged with the annular groove 4b of the housing 4, 4 is fixed to the housing 4 in a state where the rotation is prevented and the movement is stopped.

  According to the vehicle steering apparatus including the rack bush 6 configured as described above, when the rack shaft 3 supported by the rack bush 6 slides in the axial direction by the steering operation, the rack shaft 3 is enclosed in the first groove portion 62a. The grease that has moved in a spiral manner along the first groove 62 a is supplied to the sliding contact surface 62 with the rack shaft 3.

  The grease sealed in the first groove 62a moves in the first groove 62a as the rack shaft 3 and the rack bush 6 slide, and does not stay in a specific place. It is possible to prevent the grease from sticking in the groove 62a. Therefore, the grease can be stably supplied to the sliding contact surface 62 with the rack shaft 3 as the grease that can supply all the grease sealed in the first groove 62a.

  In addition, since both ends of the first groove 62a are connected by the second groove 62b formed in the axial direction, the first groove 62a moves along the first groove 62a by sliding between the rack shaft 3 and the rack bush 6. The grease that has reached one end is returned to the other end via the second groove 62b. In this way, since the grease is prevented from flowing out by circulating the grease, the grease can be held for a long period of time and stably supplied to the sliding contact surface 62.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention described in the claims. For example, in this embodiment, the rack bush is fitted to the housing by serration, but the rack bush may be fitted to the housing via an elastic ring such as an O-ring. Moreover, although applied to a manual steering device as a vehicle steering device, it may be applied to an electric power steering device.

1: Steering 2: Pinion shaft 3: Rack shaft 4: Housing
4a: mounting surface, 4b: inner peripheral surface, 4c: tapered surface, 4d: annular groove,
5, 6: rack bush, 61: main body, 61a, 61b: area,
61c, 61d: taper surface, 61e: engagement protrusion, 61f: serration,
61g, 61h: tapered surface, 61i: flat surface, 61j: ridge,
61k: taper surface, 61S slit,
62 sliding contact surface, 62a first groove, 62b second groove

Claims (2)

A pinion shaft, a rack shaft that meshes with the pinion shaft, a housing that houses the rack shaft, and the rack shaft and the housing are interposed between the rack shaft and the housing, and the rack shaft is slidably supported by the housing. In a vehicle steering apparatus comprising a rack bush,
An inner peripheral surface of the rack bush includes a first groove portion formed in a spiral shape extending from one side to the other in the axial direction on a sliding contact surface that is in sliding contact with the rack shaft, and viscous fluid is enclosed in the first groove portion. A vehicle steering apparatus. The vehicle steering device according to claim 1,
The rack bushing further includes a second groove portion formed in an axial direction connecting both ends of the first groove portion.

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