JP2005335667A - Rack and pinion type steering device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a steering delay at the beginning of steering while preventing tooth striking noise or the like at a mesh part between a rack shaft and a pinion shaft. <P>SOLUTION: This rack and pinion type steering device 10 is provided with the rack shaft 14; the pinion shaft 12 meshed with the rack shaft 14; a rack guide 20 energizing the rack shaft 14 toward the pinion shaft 12; a housing 16 for enclosing the rack guide 20; and an O-ring 70 provided between the housing 16 and the rack guide 20. The movable range of the rack guide 20 in the housing 16 is larger in a rack shaft direction than in a vertical direction of a vehicle. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a rack and pinion type steering apparatus in which a steering delay at the initial stage of steering is improved.

Conventionally, in a rack and pinion type steering apparatus including a rack shaft, a pinion shaft that meshes with the rack shaft, and a rack guide biased toward the rack shaft, an O-ring is provided between the rack guide and its housing. Thus, a technique for suppressing abnormal noise such as rattling noise at the meshing portion between the rack shaft and the pinion shaft is known (for example, see Patent Document 1).
JP 2002-321630 A

  However, providing an O-ring between the rack guide and the housing, that is, filling the gap between the rack guide and the housing with the O-ring, suppresses the movement of the rack guide relative to the housing. Therefore, this configuration has the advantage that noise such as rattling noise can be suppressed, but has the problem that the initial movement of the rack shaft at the initial stage of steering is hindered and a steering delay (response delay) at the initial stage of steering is caused. doing.

  Therefore, an object of the present invention is to provide a rack and pinion type steering device that can improve a steering delay at the initial stage of steering while preventing a rattling noise or the like at a meshing portion of a rack shaft and a pinion shaft.

In order to solve the above problems, according to one aspect of the present invention,
A rack shaft,
A pinion shaft that meshes with the rack shaft;
A rack guide that urges the rack shaft toward the pinion shaft;
A housing that houses the rack guide;
An O-ring provided between the housing and the rack guide;
A rack and pinion type steering device is provided in which the movable range of the rack guide within the housing is larger in the rack axial direction than in the vehicle vertical direction.

  In this aspect, in one embodiment, the rack guide has a cylindrical outer peripheral surface facing a cylindrical peripheral wall surface in the housing, and a peripheral groove into which the O-ring is fitted is formed on the outer peripheral surface of the rack guide. Thus, the protruding amount of the O-ring from the outer peripheral surface of the rack guide in the radial direction is smaller in the rack axis direction than in the vehicle vertical direction. In this case, the depth of the circumferential groove into which the O-ring is fitted may be larger in the rack axis direction than in the vehicle vertical direction.

  ADVANTAGE OF THE INVENTION According to this invention, the rack and pinion type steering device which can improve the steering delay at the time of steering initial stage can be obtained, preventing the rattling noise etc. in the meshing part of a rack shaft and a pinion shaft.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a cross-sectional view of an essential part showing an embodiment of a rack and pinion type steering apparatus according to the present invention. The rack and pinion type steering device 10 of this embodiment includes a pinion shaft 12. The pinion shaft 12 is connected to the steering wheel via the steering shaft. A rack shaft 14 meshes with the pinion shaft 12. The rack shaft 14 extends in the left-right direction of the vehicle, and moves to the left and right by the rotational movement of the pinion shaft 12. One end of a tie rod is connected to both ends of the rack shaft 14, and a wheel is connected to the other end of each tie rod via a knuckle arm or the like. When the steering wheel is steered, the rotation of the pinion shaft 12 is converted into the left and right movements of the rack shaft 14, and the wheels are steered through tie rods and the like.

  A rack guide 20 is provided on the rack shaft 14. The rack guide 20 supports and guides the rack shaft 14 through a guide sheet (rack guide sheet) 30 so as to be slidable. The rack guide 20 has a substantially cylindrical shape and is accommodated in the rack guide accommodating chamber 18 of the housing 16. A predetermined gap Δ is set in the radial direction of the rack guide 20 between the outer peripheral surface of the rack guide 20 and the housing 16 (the peripheral wall of the rack guide housing chamber 18). The predetermined gap Δ may be constant along the circumferential direction of the rack guide 20.

  The rack guide 20 is urged toward the rack shaft 14 by a spring 40 in order to ensure proper engagement between the rack shaft 14 and the pinion shaft 12. The guide sheet 30 provided between the rack shaft 14 and the rack guide 20 plays a role of reducing a sliding friction force between the rack shaft 14 and the rack seat 14 while being pressed toward the rack shaft 14.

  An O-ring 70 is set between the outer peripheral surface of the rack guide 20 and the housing 16 in order to reduce rattling noise at the meshing portion between the rack shaft 14 and the pinion shaft 12. The O-ring 70 is a direction perpendicular to the rack shaft (vehicle up-down direction) in order to reduce abnormal noise such as rattling noise at the meshing portion of the rack shaft 14 and the pinion shaft 12 that may occur when traveling on rough roads. It plays a role in restricting movement. On the other hand, the O-ring 70 of the present embodiment allows the rack guide 20 to move in the rack axis direction in the rack guide housing chamber 18 so as not to suppress the initial movement of the rack shaft 14 at the initial stage of steering. Hereinafter, this characteristic configuration will be described in detail.

  FIG. 2 is a side view of the rack guide 20 of the present embodiment, and FIG. 3 is a cross-sectional view taken along line AA of the rack guide 20 of FIG. The rack guide 20 is a substantially cylindrical member, as shown in FIGS. 2 and 3, and its outer diameter is slightly smaller than the diameter of the peripheral wall of the rack guide housing chamber 18 as shown in FIG. It is set small (only Δ).

  The rack guide 20 has a rack housing chamber 22 that partially houses the rack shaft 14. The rack housing chamber 22 is a semi-cylindrical space having a substantially semicircular cross section when viewed in the rack axis direction, and has a seat seat surface 24 facing the rack shaft 14. The seat seat surface 24 provides a contact surface with the back surface of the guide seat 30. The rack guide 20 has a spring accommodating chamber 26 on the opposite side to the rack accommodating chamber 22. The spring accommodating chamber 26 accommodates the above-described spring 40 for urging the rack shaft 14 toward the pinion shaft 12.

  A circumferential groove 28 is formed on the outer circumferential surface of the rack guide 20 along the circumferential direction. The above-described O-ring 70 is attached to the circumferential groove 28. The O-ring 70 may be a regular O-ring having a predetermined cross section having a predetermined diameter corresponding to the circumferential length of the circumferential groove 28. As shown in FIG. 3, the circumferential groove 28 of the present embodiment does not have a certain depth along the circumferential direction of the rack guide 20. That is, the circumferential groove 28 has an oval (elliptical) bottom surface that is long in the rack axis direction with respect to the outer peripheral surface of the circular rack guide 20 in a top view of the rack guide 20 (FIG. 3). Accordingly, the depth H of the circumferential groove 28 is small at the circumferential position of the rack guide 20 in the vehicle vertical direction, and is large at the circumferential position of the rack guide 20 in the rack axis direction. Therefore, the O-ring 70 fitted in the circumferential groove 28 protrudes greatly in the radial direction from the outer peripheral surface of the rack guide 20 at the circumferential position of the rack guide 20 in the vehicle vertical direction. At the position, a slight amount (may be zero) protrudes from the outer peripheral surface of the rack guide 20 in the radial direction.

  Therefore, in a state where the rack guide 20 is housed in the rack guide housing chamber 18, the O-ring 70 contacts (or is close to) the circumferential wall of the rack guide housing chamber 18 at the circumferential position of the rack guide 20 in the vehicle vertical direction. The rack guide 20 is spaced from the peripheral wall of the rack guide housing chamber 18 at the circumferential position in the rack axial direction. That is, the rack guide 20 is restrained from moving in the vehicle vertical direction with respect to the housing 16 by the O-ring 70, but the rack axial movement relative to the housing 16 is between the O-ring 70 and the side wall of the rack guide housing chamber 18. It is still possible by the amount of clearance.

  Next, the operation of the rack and pinion type steering device 10 of the present embodiment will be described specifically, the movement of the rack shaft 14 and the rack guide 20 during steering of the steering wheel.

  When steering of the steering wheel is started (that is, at the initial stage of steering), the rack shaft 14 is subjected to a force to move along the rack axis direction by the rotational force of the pinion shaft 12. At this time, in order for the rack shaft 14 to start moving along the rack axis direction, the force transmitted to the rack shaft 14 via the pinion shaft 12 needs to overcome the static friction force acting on the rack shaft 14. Become.

  In this regard, in a conventional configuration in which the rack guide 20 cannot be displaced in the rack axis direction within the rack guide receiving chamber 18, the rack shaft 14 starts to move until it obtains a force that overcomes the static friction force with the guide seat 30. I can't. That is, the rack shaft 14 cannot move until a steering torque sufficient to shake off the static frictional force between the guide seat 30 and the steering delay (response delay) at the initial stage of steering occurs.

  On the other hand, in the present embodiment, as described above, the rack guide 20 can be displaced in the rack axis direction within the rack guide housing chamber 18, so the rack shaft 14 starts to move along with the rack guide 20 along the rack axis direction. Can do. When the movement of the rack shaft 14 is started, the movement of the rack guide 20 in the rack guide storage chamber 18 is performed when the clearance in the rack axis direction between the O-ring 70 and the side wall of the rack guide storage chamber 18 is lost. Is suppressed. That is, from this point, the rack shaft 14 must start moving with respect to the guide seat 30. However, at this point, the rack shaft 14 itself has already started to move, so the rack shaft 14 can easily overcome the static friction force with the guide seat 30 and continue to move. As described above, according to the present embodiment, as soon as the steering of the steering wheel is started, the rack shaft 14 can start to move, so that the steering delay (response delay) at the initial stage of steering is greatly reduced.

  Further, according to the present embodiment, even when the steering direction of the steering wheel is changed, the rack shaft 14 can easily start to move due to the clearance in the rack shaft direction described above, so that the responsiveness is improved. .

  On the other hand, in this embodiment, even when a vehicle vertical direction input is applied from the wheels to the rack shaft 14 when traveling on a rough road, the rack guide 20 is prevented from moving in the vehicle vertical direction as described above. The movement of the shaft 14 in the vertical direction of the vehicle is suppressed by the rack guide 20, whereby the rattling noise at the meshing portion between the rack shaft 14 and the pinion shaft 12 is effectively suppressed.

  Next, with reference to FIG. 4, a modified example of the above-described embodiment will be described. FIG. 4 corresponds to a cross-sectional view taken along the line AA of FIG. 2 of the rack guide 20 according to this modification. In the modification of FIG. 4, the circumferential groove 28 of the rack guide 20 has a certain depth. Instead, the circumferential groove 28 of the rack guide 20 is provided with an adjustment member 72 for changing its depth. As shown in FIG. 4, the adjustment member 72 is provided at a circumferential position (two locations) in the vehicle vertical direction of the rack guide 20, and an O-ring 70 as compared with other circumferential positions (particularly, a circumferential position in the rack axis direction). It functions to greatly protrude from the outer peripheral surface of the rack guide 20. Thereby, the effect similar to the above-mentioned Example can be acquired. In this embodiment, since the circumferential groove 28 of the rack guide 20 is circular, the productivity of the rack guide 20 is good.

  The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the above-described embodiments, and various modifications and substitutions can be made to the above-described embodiments without departing from the scope of the present invention. Can be added.

  For example, in the above-described embodiment, the combination of the O-ring 70 and the circumferential groove 28 is not necessarily one set, and two or more sets may be set for one rack guide 20.

  Further, various configurations other than the above-described embodiments are conceivable in order to make the rack guide 20 easy to move in the rack axis direction and difficult to move in the vehicle vertical direction. For example, the spring constant of the O-ring 70 (the spring constant with respect to the input in the radial direction) may be reduced for the input in the rack axis direction and increased for the input in the vehicle vertical direction. Further, a circumferential groove facing the circumferential groove 28 of the rack guide 20 may be formed on the rack guide housing chamber 18 side. In this case, the circumferential groove on the rack guide housing chamber 18 side is provided only in the rack axis direction, for example. May be. Further, the depth of the circumferential groove 28 of the rack guide 20 may be constant, and the gap between the outer peripheral surface of the rack guide 20 and the peripheral wall of the rack guide housing chamber 18 may be appropriately changed along the circumferential direction. .

It is principal part sectional drawing which shows one Example of the rack and pinion type steering device by this invention. It is a side view which shows the rack guide 20 of a present Example. It is AA sectional drawing of the rack guide 20 of FIG. It is sectional drawing of the rack guide 20 by a modification.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Rack and pinion type steering device 12 Pinion shaft 14 Rack shaft 16 Housing 18 Rack guide storage chamber 20 Rack guide 22 Rack storage chamber 24 Seat seat surface 26 Spring storage chamber 28 Circumferential groove 30 Guide seat 40 Spring 70 O-ring 72 Adjustment member

Claims (3)

A rack shaft,
A pinion shaft that meshes with the rack shaft;
A rack guide that urges the rack shaft toward the pinion shaft;
A housing that houses the rack guide;
An O-ring provided between the housing and the rack guide;
A rack and pinion type steering device, wherein a movable range of a rack guide in a housing is larger in a rack axial direction than in a vehicle vertical direction.   The rack guide has a cylindrical outer peripheral surface facing a cylindrical peripheral wall surface in the housing, and a peripheral groove into which an O-ring is fitted is formed on the outer peripheral surface of the rack guide. The rack-and-pinion steering device according to claim 1, wherein an amount of radial protrusion from the outer peripheral surface of the rack is smaller in the rack axis direction than in the vehicle vertical direction.   The rack and pinion type steering device according to claim 2, wherein a depth of a circumferential groove into which the O-ring is fitted is greater in the rack axial direction than in the vehicle vertical direction.

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