JP2008230517A - Steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To mount a small diameter collar part of a boot slidably in an axial direction while easily sealingly attaching it to an outer periphery of a tie rod without clearance. <P>SOLUTION: In the steering device 10, the small diameter collar part 22 of the boot 20 is mounted to the outer periphery of the tie rod 16 slidably in an axial direction, and an O ring 16D is provided on the outer periphery of the tie rod 16 on which the small diameter collar part 22 slides. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a steering apparatus.

  Generally, a rack and pinion type steering device engages a pinion tooth of a pinion shaft that rotates in conjunction with a steering wheel with a rack tooth of a rack shaft that is fitted in a gear housing so as to be movable in the left and right directions, and The left and right rack end male threaded portions are screwed into the female threaded portion formed at the hollow end, and the left and right tie rods are connected to the left and right tie rods via the joints to the left and right rack ends protruding from the gear housing. Connect the wheels. The linear movement of the rack shaft that is interlocked with the rotation of the pinion shaft accompanying the rotation of the steering wheel is transmitted to the left and right wheels via the left and right tie rods to enable steering.

  In the steering device described in Patent Document 1, when a tie rod is connected to the rack end via a joint, the large diameter collar portion and the small diameter collar portion of the boot inserted from the anti-joint side of the tie rod are respectively connected to the gear housing and the tie rod. These are attached to the groove-like attachment portions provided by using a boot band or the like, and the grease accommodating space for the joint is sealed.

At this time, in the steering device described in Patent Document 1, the boot's expansion / contraction length (maximum) is compared with the movement distance of the tie rod by attaching the small-diameter collar portion of the boot to the outer periphery of the tie rod so as to be slidable in the axial direction. The difference between the contraction length and the maximum extension length) can be reduced, the number of ridges of the bellows-like boot can be reduced, or the difference in diameter between the peaks and valleys can be reduced. In addition to the elastic restoring force of the boot, a sliding frictional force is exerted on the tie rod, thereby widening the range of tuning of the steering feeling.
JP2002-145090

  However, in the steering device described in Patent Document 1, the small-diameter collar portion of the boot is attached to the outer periphery of the tie rod, but the small-diameter collar portion of the boot is slidable in the axial direction while being tightly sealed to the outer periphery of the tie rod. Therefore, it is difficult to finely set the dimensions of the inner diameter of the small-diameter collar portion and the outer diameter of the tie rod and finely set the tightening allowance of the small-diameter collar portion.

  An object of the present invention is to attach a small-diameter collar portion of a boot to the outer periphery of a tie rod so that the small-diameter collar portion of the boot is easily slidably attached in the axial direction while being tightly sealed to the outer periphery of the tie rod. .

  According to the first aspect of the present invention, the rack shaft is fitted into the gear housing, the tie rod is connected to the rack end protruding from the gear housing of the rack shaft via a joint, and the large diameter collar portion and the small diameter collar portion of the boot are respectively connected. In the steering device that is attached to each of the gear housing and the tie rod and seals the joint, the small diameter collar portion of the boot is slidably mounted in the axial direction with respect to the outer periphery of the tie rod, and the outer periphery of the tie rod on which the small diameter collar portion slides Is provided with a sealing material.

  According to a second aspect of the present invention, in the first aspect of the invention, the small-diameter collar portion of the boot is attached to an annular recess provided on the outer periphery of the tie rod so as to be slidable in the axial direction, and the small-diameter collar portion slides. A sealing material is provided on the outer periphery of the recess.

(Claim 1)
(a) When the small-diameter collar portion of the boot was attached to the outer periphery of the tie rod so as to be slidable in the axial direction, a sealing material was provided on the outer periphery of the tie rod on which the small-diameter collar portion slides. The dimensional difference between the inner diameter of the small collar part and the outer diameter of the tie rod is absorbed by the elastic displacement of the sealing material, and the tightening margin of the small diameter collar part is secured appropriately. It can be slidably mounted in the axial direction while being sealed without gaps.

  (b) By attaching the small-diameter collar of the boot to the outer circumference of the tie rod so as to be slidable in the axial direction, the boot stretchable length (difference between the most contracted length and the most stretched length) compared to the travel distance of the tie rod. It is possible to reduce the number of bellows-shaped boots, or to reduce the difference in diameter between the peaks and valleys. In addition to the elastic restoring force of the boot, a sliding frictional force can be exerted on the tie rod, and the range of tuning of the steering feeling can be increased.

(Claim 2)
(c) Since the annular recess in which the small-diameter collar portion of the boot slides is provided on the outer periphery of the tie rod and the sealing material is provided on the outer periphery of the annular recess, the small-diameter collar portion is sealed without gaps on the outer periphery of the annular recess The sliding range can be secured stably.

  FIG. 1 is an overall view showing a steering device, FIG. 2 is a schematic view showing a maximum extension state of the boot, and FIG. 3 is a schematic view showing a maximum compression state of the boot.

  A steering device 10 in FIG. 1 is an electric power steering device, and connects a steering column shaft to which a steering wheel is coupled to a steering shaft 12 protruding from a gear housing 11, and is connected to the steering shaft 12 via a torsion bar. A pinion shaft is connected. The steering device 10 is inserted into the gear housing 11 so that the rack shaft 13 can be moved linearly in the left-right direction, and the rack teeth of the rack shaft 13 are engaged with the pinion teeth of the above-described pinion shaft.

  The steering device 10 is configured such that the male screw portions of the left and right rack ends 14 are screwed into the female screw portions formed at the left and right hollow ends of the rack shaft 13, and the left and right rack ends 14 projecting from the gear housing 11 are coupled to the left and right rack ends 14. The left and right tie rods 16 are connected via 15 and the left and right tie rods 16 are connected to the left and right wheels.

  The steering device 10 is provided with an electric motor 17 around the rack shaft 13 inside the gear housing 11, and converts the rotation of the electric motor 17 into a linear motion of the rack shaft 13 by a ball screw (not shown). The output of 17 is transmitted to the rack shaft 13 as a steering assist force. The steering device 10 is provided with a steering torque detection device between the steering shaft 12 and the pinion shaft. The steering torque detection device detects the steering torque from the relative displacement amount of the steering shaft 12 and the pinion shaft due to the elastic torsional deformation of the torsion bar via the steering shaft 12 by the steering torque applied to the steering wheel. When the steering torque detected by the steering torque detector exceeds a predetermined value, the electric motor 17 is driven to apply a steering assist force to the rack shaft 13. As a result, the steering device 10 transmits the linear movement of the rack shaft 13 that is interlocked with the rotation of the pinion shaft accompanying the rotation of the steering wheel to the left and right wheels via the left and right tie rods 16 to enable steering. It is.

  Further, when the steering device 10 connects the tie rods 16 to the left and right rack ends 14 via the joints 15, as shown in FIG. 2, the large diameter of the bellows-like boot 20 inserted from the anti-joint 15 side of the tie rods 16. The collar portion 21 and the small-diameter collar portion 22 are fitted and attached to attachment portions 11A and 16A provided on the gear housing 11 and the tie rod 16, respectively, and the grease accommodating space for the joint 15 is sealed. The boot 20 can be made of a thermoplastic elastomer (for example, trade name Santoprene) such as a highly cross-linked olefin-based thermoplastic elastomer, but chloroprene rubber, EPDM, chlorosulfonated polyethylene, or the like can also be adopted. The mounting portion 11A of the gear housing 11 has a groove shape, and the large-diameter collar portion 21 of the boot 20 that is fastened with the boot band 18 attached to the outer peripheral groove is fixed. The structure for attaching the small-diameter collar portion 22 of the boot 20 to the attachment portion 16A of the tie rod 16 will be described later.

  However, when the steering device 10 fits the small-diameter collar portion 22 of the boot 20 to the mounting portion 16A of the tie rod 16 and attaches the boot band 19 to the outer peripheral groove of the small-diameter collar portion 22 and fastens it, In order to allow the small-diameter collar portion 22 of the boot 20 to be slidably mounted in the axial direction while sealing the outer periphery of the tie rod 16 without any gap, the following configuration is provided.

  In the steering device 10, as shown in FIG. 2, an annular recess 16 </ b> B extending over a range L longer than the axial length A of the small-diameter collar portion 22 of the boot 20 is provided on the outer periphery of the tie rod 16. The mounting portion 16A described above is used. As a result, the small-diameter collar portion 22 of the boot 20 is slidably attached in the axial range L to the outer periphery of the annular recess 16B as the attachment portion 16A provided on the outer periphery of the tie rod 16. The inner periphery of the small-diameter collar portion 22 that is in sliding contact with the outer periphery of the annular recess 16B forms a smooth surface. FIG. 2 shows that when the rack shaft 13 moves to one end of the left-right linear movement, the tie rod 16 reaches one movement limit, and when the boot 20 reaches the maximum extension state, the small-diameter collar portion 22 of the boot 20 is annular. A state in which the concave portion 16B is slid and brought into contact with one end thereof is shown. FIG. 3 shows that when the rack shaft 13 moves to the other end of the left-right linear movement, the tie rod 16 reaches the other movement limit, and when the boot 20 reaches the most contracted state, the small-diameter collar portion 22 of the boot 20 is annular. The state which reached the other end by sliding the recessed part 16B is shown.

  Further, in the steering device 10, the small-diameter collar portion 22 is always fitted on the outer periphery of the attachment portion 16A (annular recess 16B) of the tie rod 16 on which the small-diameter collar portion 22 of the boot 20 slides. A sealing material loading groove 16C is provided at the position, and an O-ring 16D as a sealing material is provided in the sealing material loading groove 16C. Thereby, the inner peripheral smooth surface of the small-diameter collar portion 22 of the boot 20 is always in sliding contact with the outer periphery of the annular recess 16B and the O-ring 16D in the range L of the annular recess 16B of the tie rod 16.

According to the present embodiment, the following operational effects can be obtained.
(a) When the small diameter collar portion 22 of the boot 20 is attached to the outer periphery of the tie rod 16 so as to be slidable in the axial direction, an O-ring 16D is provided on the outer periphery of the tie rod 16 on which the small diameter collar portion 22 slides. The dimensional difference between the inner diameter of the small-diameter collar portion 22 and the outer diameter of the tie rod 16 is absorbed by the elastic displacement of the O-ring 16D, and the tightening margin of the small-diameter collar portion 22 is secured appropriately. The portion 22 can be slidably attached in the axial direction while being sealed to the outer periphery of the tie rod 16 without a gap.

  (b) By attaching the small-diameter collar portion 22 of the boot 20 to the outer periphery of the tie rod 16 so as to be slidable in the axial direction, the expansion / contraction length (the most contracted length and the most elongated length) of the boot 20 compared to the moving distance of the tie rod 16 The difference in thickness) can be reduced, and the number of peaks of the bellows-like boot 20 can be reduced, or the difference in diameter between the peaks and valleys can be reduced. In addition to the elastic restoring force of the boot 20, a sliding friction force can be exerted on the tie rod 16 to widen the tuning range of the steering feeling.

  (c) Since the annular recess 16B in which the small-diameter collar portion 22 of the boot 20 slides is provided on the outer periphery of the tie rod 16, and the O-ring 16D is provided on the outer periphery of the annular recess 16B, the small-diameter collar portion 22 is provided on the outer periphery of the annular recess 16B. The sliding range can be stably secured while sealing without gaps.

  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 attachment portion 16A of the tie rod 16 with which the small diameter collar portion 22 of the boot 20 comes into sliding contact does not necessarily have to be the annular recess 16B. The present invention can also be applied to a hydraulic power steering apparatus.

FIG. 1 is an overall view showing a steering apparatus. FIG. 2 is a schematic diagram showing the most extended state of the boot. FIG. 3 is a schematic view showing the most compressed state of the boot.

Explanation of symbols

10 Steering device 11 Gear housing 13 Rack shaft 14 Rack end 15 Joint 16 Tie rod 16B Annular recess 16D O-ring (seal material)
20 Boot 21 Large diameter collar 22 Small diameter collar

Claims (2)

Insert the rack shaft into the gear housing, connect the tie rod to the rack end protruding from the gear housing of the rack shaft through a joint,
In the steering device for attaching the large diameter collar part and the small diameter collar part of the boot to the gear housing and the tie rod, respectively, and sealing the joint,
A steering device, wherein a small-diameter collar portion of a boot is slidably attached to an outer periphery of a tie rod in an axial direction, and a seal material is provided on an outer periphery of a tie rod on which the small-diameter collar portion slides.   The small diameter collar part of the said boot is attached to the annular recessed part provided in the outer periphery of the tie rod so that sliding is possible in an axial direction, The sealing material was provided in the outer periphery of the annular recessed part which this small diameter collar part slides. Steering device.

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