JP2009227030A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a steering device capable of easily securing the accuracy of an axial position of an end cap in a cylinder tube, and also capable of suppressing unnecessary increase of its weight. <P>SOLUTION: An inner end surface 7b of a ball joint 7 connecting a tie-rod 8 to the end part of a rack shaft abuts on the periphery of the one end part of the cylinder tube 11 penetratingly equipped with a rack shaft 6 at its inner circumference side; thus the end cap 12 regulates a maximum axial movement position of the rack shaft, and is screwed in the steering device. The end cap is mounted so that a receiving surface 14a of one end side abuts on one end surface 11a of the cylinder tube, while the other end side is configured to project outward from one end of the cylinder tube, and the device is mounted on a vehicle through this projected part. Thereby, the positional accuracy of the end cap is determined by the axial length of the cylinder tube to enhance the positional accuracy of the end cap. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an improvement in a steering device that is applied to, for example, a rack and pinion type power steering device of a vehicle and restricts axial movement of a rack shaft by providing an end cap at an axial end portion of a cylinder tube.

  As a conventional rack and pinion type steering device for a vehicle, for example, one described in Patent Document 1 below is known.

  In this steering device, a hollow cylindrical rack shaft that meshes with a pinion shaft is provided in the cylinder tube so as to be movable in the axial direction, and a tie rod linked to a wheel is rotatable at an end of the rack shaft. A ball joint for supporting the ball is connected. A substantially cylindrical end cap that restricts the maximum movement position of the rack shaft in the axial direction by contacting the inner end surface of the ball joint is disposed on the inner peripheral side near the axial end of the cylinder tube. The end cap is attached to the vehicle body via a vehicle body attachment portion formed on the outer periphery of the axial end portion of the cylinder tube on the outer end side with respect to the axial position where the end cap is disposed.

An end portion in the axial direction of the cylinder tube is formed in a stepped diameter increasing shape by press molding, and the end cap is screwed so as to abut against the stepped surface. That is, the end cap is brought into contact with the stepped surface, whereby the axial load input from the ball joint can be received by the stepped surface. Thus, the axial load input from the ball joint to the end cap at the time of turning does not reach the threaded portion of the end cap with the cylinder tube.
JP 2001-260915 A

  However, in the conventional steering device, since the stepped portion for abutting the end cap against the axial end of the cylinder tube is formed by press molding, the axial position of the end cap with respect to the cylinder tube The technical problem that it was difficult to ensure accuracy was invited.

  Further, since the axial load when the ball joint comes into contact with the end cap is received by the step portion of the cylinder tube, the axial end of the cylinder tube is secured in order to ensure the strength of the step portion. The part had to be formed thicker than necessary, and the weight of the apparatus was inevitably increased.

  The present invention has been devised by paying attention to such a technical problem, and can easily secure the accuracy of the axial position of the end cap in the cylinder tube, while suppressing an unnecessary increase in weight. The obtained steering device is provided.

  In the present invention, in particular, the end cap is configured such that one end side in the axial direction is attached to the end face in the axial direction of the cylinder tube and the other end side is projected outward from the end face in the axial direction of the cylinder tube. The apparatus is attached to the vehicle body through a portion protruding from the axial end surface of the cylinder tube.

  Hereinafter, embodiments of a steering apparatus according to the present invention will be described in detail with reference to the drawings. In each of the embodiments, the steering device according to the present invention is applied to a rack and pinion type power steering device of a vehicle as in the prior art.

  That is, FIGS. 1 to 3 show a first embodiment of a steering device according to the present invention. As shown in FIG. 3, one end side of the power steering device is linked to a steering wheel (not shown). A steering shaft 1 that rotates when the steering wheel is steered, a gear box 2 that houses the other end side of the steering shaft 1 and is biased to one end in the width direction of the vehicle body, A rack housing 3 provided at the lower end portion and extending in the width direction of the vehicle body, and a power cylinder 4 joined in the axial direction of the rack housing 3 are provided.

  The gear box 2 has a rod-like torsion bar 5 connected to the steering shaft 1 on one end side, a rotary valve (not shown) provided so as to surround the torsion bar 5, and one end side via the torsion bar 5. An unillustrated pinion shaft connected to the steering shaft 1 is housed inside. The rotary valve controls the amount of hydraulic oil supplied to the power cylinder 4 by twisting the torsion bar 5 with the rotation of the steering shaft 1 and opening and closing the internal oil passage in accordance with the twist amount. is doing.

  The rack housing 3 includes a substantially cylindrical rack shaft 6 that is engaged with the other end portion of the pinion shaft and the other end portion of the pinion shaft so as to move forward and backward in the axial direction according to the rotation of the steering wheel. The rack shaft 6 is provided across the rack housing 3 and the power cylinder 4. Further, tie rods 8 and 8 are coupled to both ends of the rack shaft 6 via ball joints 7 and 7 which are shaft joints, respectively, and a knuckle (not shown) connected to the outer ends of the tie rods 8 and 8 is connected. Via the left and right wheels.

  With such a configuration, the power steering device moves the rack shaft 6 in the axial direction in accordance with the rotation angle of the steering wheel, and pulls the knuckle left and right through the tie rods 8 and 8 so that both wheels The direction is changed, and the traveling direction of the vehicle is changed.

  In the power cylinder 4, a rack shaft 6 is accommodated in an inner peripheral side of a substantially cylindrical cylinder tube 11 made of an aluminum alloy material or iron material, and a piston (not shown) provided on the outer peripheral side of the rack shaft 6. Are separated into two pressure chambers, a first pressure chamber P1 configured on the right side in FIG. 3 and a second pressure chamber P2 configured on the left side in FIG. In the power cylinder 4, the hydraulic pressure supplied to each of the pressure chambers P 1 and P 2 via the first oil passage pipe 9 a and the second oil passage pipe 9 b connected to the gear housing 2 is supplied to the rack shaft 6. By assisting the movement in the axial direction, the steering force of the driver is assisted.

  The ball joint 7 is a well-known ball joint, and protrudes from a substantially cylindrical holding portion 7a for holding a spherical portion 8a provided at the inner end portion of the tie rod 8, and an inner end surface 7b of the holding portion 7a. And a shaft portion 7c screwed into the inner peripheral side of the end portion of the rack shaft 6. The spherical portion 8a is accommodated and held on a spherical sliding surface formed on the inner peripheral side of the holding portion 7a. Thus, the tie rod 8 is supported in a three-dimensionally rotatable manner with the spherical portion 8a as a fulcrum.

  The holding portion 7 a is screwed to the rack shaft 6 with the inner end surface 7 b being abutted against the end surface of the rack shaft 6, and the outer diameter of the inner end surface 7 b is the end surface of the rack shaft 6. It is set to be no less than the outer diameter, and comes into contact with a regulating wall 15a of the receiving portion 15 of the end cap 12 to be described later when the rack shaft 6 moves the most in the left direction in FIG.

  As shown in FIGS. 1 and 2, the cylinder tube 11 is configured in a straight shape without a step at one end portion, and an annular oil seal 10 is press-fitted and fixed to the inner peripheral side of the one end portion. Thus, the outer end side of the first pressure chamber P1 is liquid-tightly sealed by the oil seal 10.

  Then, the ball seal 7 is brought into contact with one end portion of the power cylinder 4 so as to hold the oil seal 10, thereby restricting the maximum movement position of the rack shaft 6 in the left direction in FIG. 3. An end cap 12 is provided so as to close the opening at one end of the cylinder tube 11.

  Further, as shown in FIG. 3, the power cylinder 4 is a cylindrical mount made of a rubber material disposed on each outer peripheral portion of the rack housing 3 and the end cap 12 which are both ends of the power cylinder 4. It is attached to the vehicle body via a member 13. The mount member 13 is connected to the vehicle body via a metal bracket (not shown) provided on the outer peripheral side of the mount member 13.

  As shown in FIGS. 1 and 2, the end cap 12 is formed in a substantially cylindrical shape by an aluminum alloy material, and is configured to be concave on one end side in the axial direction so as to abut against one end surface 11 a of the cylinder tube 11. A mounting portion 14 that is mounted in a state, a receiving portion 15 that is configured to be concave on the other end side and receives the ball joint 7 when the rack shaft 6 is moved, and a thick wall that defines the mounting portion 14 and the receiving portion 15 And a vehicle body attachment portion 17 that is set to a predetermined range in the axial direction of the outer peripheral surface and is attached to the vehicle body via the mount member 13.

  The mounting portion 14 has a female screw portion 14b that is screwed into a male screw portion 11b formed on the outer peripheral surface of one end portion of the cylinder tube 11 in substantially the entire axial range of the peripheral wall surface. Screwed to the outer periphery. And this attachment part 14 is attached in the state where the inner end surface was abutted against one end surface 11a of the cylinder tube 11 as a receiving surface 14a for receiving the one end surface 11a of the cylinder tube 11.

  An annular groove 14c is formed in the circumferential wall surface of the inner end portion of the mounting portion 14 along the circumferential direction, and a so-called O-ring 18 serving as a sealing means is fitted in the annular groove 14c. The O-ring 18 protects one end of the power cylinder 4 from dust and water. Furthermore, a sealing agent (not shown) as a sealing means is also interposed between the screw parts 11b and 14b, and the inflow of dust and muddy water from the outside is caused by a synergistic sealing action with the O-ring 18. It is effectively prevented.

  The receiving portion 15 has a larger diameter than the maximum outer diameter portion of the holding portion 7a of the ball joint 7, and is set so that the diameter is uniform in the axial direction, so that the entire ball joint 7 is received. It is configured to be possible. Then, at the inner end portion of the receiving portion 15, the rack shaft 6 abuts on the inner end surface 7 b of the ball joint 7 when the rack shaft 6 moves the most in the left direction in FIG. A restriction wall 15a for restricting movement is configured.

  In addition, one end of a boot member 19 formed of a rubber material or a resin material so as to be freely stretchable is fixed to the outer periphery of the distal end portion of the receiving portion 15 by a band or wire made of a generic material. 19 protects the ball joint 7 from dust and muddy water.

  The thick portion 16 is set to have an inner diameter slightly larger than the outer diameter of the rack shaft 6, and a substantially cylindrical bush 20 is fitted on the inner peripheral surface. The bush 20 is formed thin with a resin material, and supports the outer end portion of the rack shaft 6 slidably without rattling.

  The vehicle body mounting portion 17 refers to an axial range in which the mount member 13 is fitted, and is set so as to straddle the receiving portion 15 and the thick portion 16. In other words, the vehicle body attachment portion 17 is set so that a portion (a portion indicated by W in FIG. 1) that overlaps with the thick portion 16 is formed at least in the radial direction.

  From the above, the steering device according to the present embodiment attaches the end cap 12 to the cylinder tube 11 via the attachment portion 14 in a state where the receiving surface 14a is abutted against the one end surface 11a of the cylinder tube 11. The end cap 12 is protruded greatly outward from one end of the cylinder tube 11, and the vehicle body mounting portion 17 is set on the end cap 12.

  That is, according to such a configuration, the vehicle body mounting portion 17 is not set at one end of the cylinder tube 11, and the axial load input from the ball joint 7 to the end cap 12 when the movement of the rack shaft 6 is restricted. Can be received by the one end surface 11 a of the cylinder tube 11.

  Therefore, in the steering device according to the present embodiment, it is not necessary to process and extend one end of the cylinder tube 11 into a stepped diameter shape unlike the prior art, and the axial direction of the end cap 12 The position accuracy can be determined with the processing accuracy of the axial length of the cylinder tube 11. As a result, the position accuracy of the end cap 12 is higher than that of the conventional technique in which the position accuracy of the end cap 12 is determined with the processing accuracy of the stepped portion obtained by processing one end portion of the cylinder tube 11 into a stepped diameter increasing shape. Can be secured.

  Thereby, the stroke amount of the rack shaft 6 can be appropriately managed without exerting the axial load on the cylinder tube 11, the end cap 12, and the both screw portions 11b and 14b.

  Moreover, since the axial load input from the ball joint 7 to the end cap 12 when the movement of the rack shaft 6 is restricted is received by the entire one end surface 11a of the cylinder tube 11 through the receiving surface 14a, the shaft Compared with the prior art having a structure in which the directional load is received by the stepped surface formed in the stepped portion, sufficient strength can be ensured while the one end portion of the cylinder tube 11 is formed relatively thin.

  Further, in the present embodiment, since the end cap 12 is screwed to the outer periphery of the one end portion of the cylinder tube 11, the radial distance from the shaft center is gained compared to the configuration of screwing to the inner peripheral side. Is possible. As a result, when a force in a direction perpendicular to the axis acts on the end cap 12 via the mount member 13, the moment generated in the both screw portions 11 b and 14 b can be reduced accordingly. It is used to improve strength.

  Further, since the vehicle body mounting portion 17 is set so as to straddle the receiving portion 15 and the thick portion 16, a part of the load input from the mount member 13 to the end cap 12 is received by the thick portion 16. Therefore, the mounting strength with respect to the vehicle body can be improved.

  FIG. 4 shows a second embodiment of the steering apparatus according to the present invention, the basic configuration is the same as that of the first embodiment, and the diameter of the receiving portion 15 is outside the end cap 12. The peripheral wall surface of the receiving portion 15 is formed in a substantially tapered shape along the axial direction so that the diameter gradually increases toward the end side.

  According to this embodiment, since the peripheral wall surface of the receiving portion 15 of the end cap 12 is formed in a tapered shape as described above, the rotation of the tie rod 8 can be performed without increasing the diameter of the end cap 12. A larger angle can be secured. In addition, in this case, an appropriate thickness can be ensured for the peripheral wall on the inner end side of the receiving portion 15 that becomes the vehicle body attachment portion 17, so that the attachment strength to the vehicle body is not impaired.

  The present invention is not limited to the configuration of each of the embodiments described above, and for example, the shape and size of the end cap 12 can be freely changed according to the specifications and size of the steering device.

  Further, in each of the above embodiments, a structure in which the end cap 12 is screwed to the outer periphery of the one end portion of the cylinder tube 11 is employed, but for the end cap 12, the mounting portion 14 is formed in a convex shaft shape. By forming a flange-like annular protrusion on the outer periphery of the base end of the mounting portion 14 and abutting against one end surface 11a of the cylinder tube 11 as a receiving surface on the inner surface of the annular protrusion, the cylinder It is also possible to screw the tube 11 to the inner periphery of one end portion. In this case, although it is disadvantageous in terms of the strength of the screw parts 11b and 14b as described above, the same operational effects as those of the first embodiment are obtained except for this point.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a first embodiment of a steering apparatus according to the present invention, and is a longitudinal sectional view in the vicinity of an end portion in an axial direction of a cylinder tube for explaining main parts of the present invention. It is a principal part enlarged view of the outer end part vicinity which shows the attachment state of the end cap with respect to the cylinder tube in FIG. 1 is an overall view of a steering device showing a first embodiment of the steering device. It is a longitudinal cross-sectional view of the axial direction vicinity of the cylinder tube which shows 2nd Embodiment of the steering device which concerns on this invention, and demonstrates the principal part of this invention.

Explanation of symbols

6 ... Rack shaft 7 ... Ball joint (shaft coupling)
7b ... Inner side surface of ball joint holding part (inner end surface of shaft coupling)
8 ... Tie rod 11 ... Cylinder tube 11a ... One end surface 12 of the cylinder tube ... End cap 14a ... Receiving surface of the cylinder tube (one end side of the cylinder tube)

Claims (5)

A rack shaft provided in the cylinder tube so as to be movable in the axial direction;
A shaft coupling rotatably connecting tie rods linked to wheels to both ends of the rack shaft;
An end cap that is attached to one end of the cylinder tube in the axial direction and regulates the maximum movement position of the rack shaft in the axial direction by contacting an inner end surface of the shaft coupling;
The end cap is configured such that one end side in the axial direction is attached to abutment with one end face in the axial direction of the cylinder tube, and the other end side protrudes outward from one end face in the axial direction of the cylinder tube. A steering device, wherein the steering device is attached to a vehicle body through a portion protruding from one axial end surface of the cylinder tube. The steering device according to claim 1, wherein the end cap is screwed onto an outer periphery of one axial end portion of the cylinder tube. The steering apparatus according to claim 2, wherein a sealing means is interposed between the threaded portions of the cylinder tube and the end cap. The end cap is formed on one end side in the axial direction and is attached to the end face in the axial direction of the cylinder tube in an abutting state; and
A receiving portion that is formed on the inner circumference on the other end side and receives the shaft coupling when contacting the inner end surface of the shaft coupling;
A thick portion defining an axial direction of the mounting portion and the receiving portion;
It is configured on the outer peripheral side of the portion protruding from the axial end surface of the cylinder tube, and has a vehicle body attachment portion attached to the vehicle body,
The steering device according to claim 1, wherein the vehicle body attachment portion is configured to straddle the thick portion and the receiving portion. 5. The steering apparatus according to claim 4, wherein a peripheral wall surface of the receiving portion is formed in a substantially tapered shape along the axial direction so that the diameter of the receiving portion gradually increases toward the outer end side. .

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