JP2009202742A - Power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To support a rack shaft by a bush without backlash while retaining the bush by the bearing retaining section of a rack housing without backlash. <P>SOLUTION: In this power steering system 10 formed by supporting the rack shaft 15 by the bush 34 retained by the bearing retaining section 32 of the rack housing 14, one axial end surface of the bush 34 abuts on the bush receiving surface 32A of the bearing retaining section 32, the outer periphery of the bush 34 is provided with a tapered outer peripheral surface 34B with a diameter contracted toward the axial other end, a collar 35 is attached to the axial other end of the bush 34, and an elastic member 37 is provided for push-pressing the tapered inner peripheral surface 35B provided to the collar 35 to the tapered outer peripheral surface 34B of the bush 34. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a power steering device such as a hydraulic power steering device or an electric power steering device.

Conventionally, in a power steering apparatus, as described in Patent Document 1, a rack shaft is supported by a bush held by a bearing holding portion of a rack housing. At this time, an elastic member is interposed between the bearing holding portion and the bush, and the inner periphery of the bush tightened radially inward by this elastic member reduces or eliminates the gap between the outer periphery of the rack shaft, The collision noise between the rack shaft outer periphery and the bush inner periphery due to play (fine vibration) can be reduced.
5-49566

  In the power steering device described in Patent Document 1, as a result of the elastic member tightening the bush radially inward, a new gap is generated between the outer periphery of the bush and the inner periphery of the bearing holding portion while the rack repeats reciprocating motion. When traveling on rough roads, there is a possibility that a collision noise between the two due to backlash between the outer periphery of the bush and the inner periphery of the bearing holding portion may occur.

  Further, when the bush moves with the reciprocation of the rack shaft, there is a possibility that a collision noise between the both ends due to the backlash between the end surface of the bush and the side wall of the bearing holding portion is generated.

  SUMMARY OF THE INVENTION An object of the present invention is to support a rack shaft without backlash by this bush while holding the bush without backlash on the bearing holding portion of the rack housing.

  In the power steering device in which the rack shaft is supported by the bush held in the bearing holding portion of the rack housing, the end surface on one end side in the axial direction of the bush is applied to the bush receiving surface of the bearing holding portion. The outer periphery of the bush is provided with a tapered outer peripheral surface that is reduced in diameter toward the other end side in the axial direction, the collar is attached to the other end side in the axial direction of the bush, and the tapered inner peripheral surface provided on the collar is the outer periphery of the taper of the bush. A resilient member that presses against the surface is provided.

  According to a second aspect of the present invention, in the first aspect of the present invention, the collar is inserted into the bearing holding portion via a vibration isolating member.

(Claim 1)
(a) A resilient member that presses the tapered inner peripheral surface of the collar against the tapered outer peripheral surface of the bush is provided. Therefore, the bush is pressed in the axial direction by the collar backed up by the spring force of the resilient member and pressed against the bush receiving surface of the bearing holding portion, and the bush is pressed in the inner diameter direction by the collar to It is pressed against the gap without any gap. As a result, even if the bush is worn due to contact with the rack shaft or the like, or even if the rack shaft is bent due to an external force when traveling on a rough road, the bush is always held in the bearing holding portion without looseness, the rack shaft is Support without play. There is no collision noise between the bush and the bearing holding part due to backlash between the bush and the bearing holding part, and neither between them due to backlash between the bush and the rack shaft.

(Claim 2)
(b) The collar is inserted into the bearing holding portion via the vibration isolation member. Therefore, when the vehicle travels on a rough road, the collar does not generate a collision noise between the collar and the bearing holding portion.

  1 is an overall view showing a hydraulic power steering apparatus, FIG. 2 is an enlarged view of a main part of FIG. 1, FIG. 3 is a sectional view showing a bush holding structure using a collar, and FIG. 4 is a section showing a modification of the bush holding structure using a collar. FIG.

  The hydraulic power steering apparatus 10 in FIG. 1 has a gear box 11. The gear box 11 includes a gear housing 12 and a cylinder tube 14 (rack housing) of the power cylinder 13. One end of the cylinder tube 14 is press-fitted and fixed to the outer periphery of the cylindrical mounting portion 12 </ b> A of the gear housing 12.

  The hydraulic power steering apparatus 10 has a hollow rack shaft 15 slidably fitted in oil chambers 17A and 17B formed by the gear housing 12 and the cylinder tube 14 of the gear box 11, and the cylinder tube 14 is mounted on the rack shaft 15. The piston 16 that is slidably fitted is fixed. The power cylinder 13 divides the oil chambers 17A and 17B of the cylinder tube 14 into a first chamber 17A and a second chamber 17B by a piston 16. The first chamber 17A is loaded on one end side of the cylinder tube 14 and sealed with an oil seal 18A that is in sliding contact with the outer periphery of the rack shaft 15, and the second chamber 17B is loaded on the other end side of the cylinder tube 14 and mounted on the rack shaft 15. It is sealed by an oil seal 18B that is in sliding contact with the outer periphery of the oil.

  In the hydraulic power steering apparatus 10, a valve body 21 of a control valve 20 is fixed to a gear housing 12. The control valve 20 pivotally supports an input shaft 22 that rotates in conjunction with the steering wheel on the valve body 21, and includes a circular rotor (not shown) integrated with the input shaft 22 and a torsion bar 22 </ b> A fixed to the input shaft 22. A circular sleeve (not shown) fixed together with a pinion (not shown) at the tip is coaxially arranged so as to be relatively displaceable by elastic torsional deformation of the torsion bar 22A according to the steering torque applied to the steering wheel. The pump-side supply flow path and the tank-side return flow path are switched and connected to the first and second supply / discharge flow paths 19A and 19B connected to the first chamber 17A and the second chamber 17B, respectively, according to the steering operation. A pinion (not shown) fixed to the sleeve (not shown) is engaged with the rack teeth of the rack shaft 15.

  As shown in FIG. 2, the hydraulic power steering apparatus 10 includes a cylinder tube 14 of a power cylinder 13 made of a thin steel pipe, and an iron cylinder end 30 is screwed onto a threaded portion on the inner periphery of the other end of the cylinder tube 14. Fix it. A shoulder surface 31 provided at an intermediate portion in the axial direction of the cylinder end 30 abuts against an end surface of the cylinder tube 14. One end of the rack shaft 15 is supported inside the gear housing 12 by a rack guide (not shown) provided on the back side of the meshing portion with the pinion shaft, and the other end of the rack shaft 15 is a bearing on the inner periphery of the cylinder end 30. It is supported by a metal bush 33 and a resin bush 34 held by the holding portion 32. The resin bushing 34 is disposed adjacent to the anti-oil chamber 17B side of the metal bush 33, has an inner diameter smaller than that of the metal bush 33, and supports the rack shaft 15 with a tight fit. In the cylinder tube 14, an oil seal 18 </ b> A that is loaded on one end side of the cylinder tube 14 and seals the first chamber 17 </ b> A is backed up by a backup ring 12 </ b> B provided between the end face of the cylindrical mounting portion 12 </ b> A of the gear housing 12. The oil seal 18B that is loaded on the other end side of the cylinder tube 14 and seals the second chamber 17B is backed up by the end face of the cylinder end 30.

  The hydraulic power steering apparatus 10 projects both ends of the rack shaft 15 to the left and right of the gear box 11, and screwes and fixes the male thread portions of the left and right rack ends 40 to the inner periphery of these ends. The left and right tie rods 41 are connected to each other, and the wheels are connected to the tie rods 41 so that the left and right wheels can be steered. At one end side of the gear box 11, both end portions of the rubber boot 42 </ b> A are fastened to and spanned from the end portion of the gear housing 12 and one of the tie rods 41 (end portion of the rack shaft 15), and project from the gear box 11. One end of the rack shaft 15 to be covered is covered. On the other end side of the gear box 11, both end portions of the rubber boot 42 </ b> B are fastened to and spanned from the end portion of the cylinder end 30 and the other tie rod 41 (end portion of the rack shaft 15). The other end of the protruding rack shaft 15 is covered. Air holes 15 </ b> A penetrating into and out of the hollow portion of the rack shaft 15 are formed in the vicinity of both ends of the rack shaft 15 protruding from the gear box 11. As a result, when the rack shaft 15 strokes left and right and the one rubber boot 42A and the other rubber boot 42B expand and contract with each other, the air in the rubber boot 42A and the air in the rubber boot 42B are removed from the air hole 15A and the hollow portion of the rack shaft 15. The rubber boots 42A and 42B are allowed to expand and contract.

  The hydraulic power steering device 10 controls the supply and discharge of pressure oil to and from the first chamber 17A and the second chamber 17B of the power cylinder 13 by the above-described operation of the control valve interlocked with the steering operation. The tie rod 41 is driven to assist the steering force of the steering wheel by the driver.

  At this time, in the hydraulic power steering apparatus 10, as described above, the bearing holding portion 32 for the rack shaft 15 provided in the cylinder end 30 includes the metal bush 33 and the anti-oil chamber 17B side of the metal bush 33. The resin bush 34 is disposed adjacent to the metal bush 33 and has a smaller inner diameter than the metal bush 33. As a result, the backlash (microvibration) of the rack shaft 15 due to the clearance between the rack shaft 15 and the metal bush 33 is absorbed by the resin bush 34, so that no abnormal noise is generated. Further, since the heavy load of the rack shaft 15 can be received by the metal bush 33, the rack shaft 15 is not hindered in operation. Furthermore, in order to eliminate the backlash of the rack shaft 15, it is not necessary to specially improve the accuracy of the metal bush 33 and the rack shaft 15, and these accuracy can be made appropriate.

  However, in the hydraulic power steering apparatus 10, the resin bush 34 is held without play in the bearing holding portion 32 of the cylinder end 30 fixed to the cylinder tube 14, and the rack shaft 15 is supported by the resin bush 34 without play. Therefore, it has the following configuration (FIG. 3).

  (1) An end surface 34A (a plane perpendicular to the axial direction of the resin bush 34) on one end side in the axial direction of the resin bush 34 is a bush receiving surface 32A of the bearing holding portion 32 (a plane orthogonal to the axial direction of the bearing holding portion 32). Then, a tapered outer peripheral surface 34B having a diameter reduced toward the other end side in the axial direction is provided on the outer periphery of the resin bush 34.

  The resin bushing 34 has a C-ring shape with a slit (not shown) by cutting at one place in the circumferential direction, and can be elastically expanded and contracted in the radial direction.

  (2) A collar 35 fitted into the inner periphery of the bearing holding portion 32 is provided, and this collar 35 is attached to the other end side of the resin bush 34 in the axial direction. An anti-vibration member 36 made of an O-ring is loaded into an annular groove 35 </ b> A provided on the outer periphery of the collar 35, and the collar 35 is fitted into the inner periphery of the bearing holder 32 via the anti-vibration member 36.

  The resilient member 37 that presses the collar 35 and the spring receiving surface 32B of the bearing holding portion 32 and the collar 35 so that the tapered inner circumferential surface 35B provided on the collar 35 is in contact with the tapered outer circumferential surface 34B of the resin bush 34 without a gap. It is interposed between the end faces of the. The elastic member 37 consists of a coil spring.

According to the present embodiment, the following operational effects can be obtained.
(a) A resilient member 37 that presses the tapered inner peripheral surface 35B provided on the collar 35 against the tapered outer peripheral surface 34B of the resin bush 34 is provided. Accordingly, the resin bush 34 is pressed in the axial direction by the collar 35 backed up by the spring force of the elastic member 37 and pressed against the bush receiving surface 32A of the bearing holding portion 32, and the resin bush 34 has an inner diameter by the collar 35. It is pressed in the direction and pressed against the outer periphery of the rack shaft without any gap. As a result, even if the resin bush 34 is worn due to contact with the rack shaft or the like, or even if the rack shaft is bent due to an external force when traveling on a rough road, the resin bush 34 is always held by the bearing holding portion 32 without backlash. However, the rack shaft is supported without play. There is no collision noise between the resin bush 34 and the bearing holding portion 32 due to the backlash between the resin bush 34 and the bearing holder 32, and neither between the resin bush 34 and the rack shaft due to backlash.

  By changing the taper angle between the taper outer peripheral surface 34B of the resin bush 34 and the taper inner peripheral surface 35B of the collar 35, and adjusting the spring force of the elastic member 37, the resin bush 34 is supported by the bush receiving surface of the bearing holding portion 32. The load pressed against the outer periphery of 32A and the rack shaft 15 can be adjusted, and the sliding resistance force which the resin bush 34 exerts on the rack shaft 15 can be adjusted. The bending resistance force that the resin bushing 34 exerts on the rack shaft 15 can also be adjusted.

  (b) The collar 35 is inserted into the bearing holding portion 32 through the vibration isolation member 36. Therefore, when the vehicle travels on a rough road, the collar 35 does not generate a collision sound between the collar 35 and the bearing holding portion 32.

  The resilient member 37 that presses the tapered inner circumferential surface 35B of the collar 35 against the tapered outer circumferential surface 34B of the resin bush 34 may be a disc spring or the like as shown in FIG.

  Although the embodiments of the present invention have been described in detail with reference to the drawings, the specific configuration of the present invention is not limited to these embodiments, and even if there is a design change or the like without departing from the gist of the present invention. It is included in the present invention. For example, the present invention can be applied to an electric power steering apparatus.

FIG. 1 is an overall view showing a hydraulic power steering apparatus. FIG. 2 is an enlarged view of a main part of FIG. FIG. 3 is a sectional view showing a bush holding structure using a collar. FIG. 4 is a cross-sectional view showing a modified example of the bush holding structure using the collar.

Explanation of symbols

10 Power steering device 14 Cylinder tube (rack housing)
15 Rack shaft 32 Bearing holding portion 32A Bushing receiving surface 34 Bushing 34B Taper outer peripheral surface 35 Collar 35B Taper inner peripheral surface 36 Anti-vibration member 37 Elastic member

Claims (2)

In a power steering device in which a rack shaft is supported by a bush held in a bearing holding portion of a rack housing,
The end surface on one end side in the axial direction of the bush is applied to the bush receiving surface of the bearing holding portion, and a tapered outer peripheral surface that reduces the diameter toward the other end side in the axial direction is provided on the outer periphery of the bush.
A power steering apparatus comprising: a collar attached to the other end side of the bush in the axial direction; and a resilient member for pressing a tapered inner peripheral surface provided on the collar against a tapered outer peripheral surface of the bush.   The power steering device according to claim 1, wherein the collar is inserted into the bearing holding portion via a vibration isolation member.

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