JP2013035481A - Shock absorbing member for rack stroke end and shock absorber for rack stroke end - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a shock absorbing member for a rack stroke end and a shock absorber for a rack stroke end that enables easy mounting with excellent mounting stability, and has greater flexibility in design.SOLUTION: At an end on the rack end 51 side of a rack housing 30, a circular cut-out portion 33 is formed along the edge of the opening of an insertion hole 31 into which a rack shaft 40 is inserted. A shock absorbing member includes: a shock absorbing portion 11 that is sandwiched between the surface of the cut-out portion 33 facing the rack end 51 and the rack end 51, and absorbs shock; and an insertion portion 12 that is inserted into the insertion hole 31 beyond the circular cut-out portion 33. The insertion portion 12 is provided with an engaging projection 13 that engages with an engaging recess 34 formed on the inner peripheral surface of the insertion hole 31.

Description

  The present invention relates to a rack end stroke shock absorber and a rack stroke end shock absorber provided in a steering mechanism.

  The rack-and-pinion type steering mechanism has a rack stroke end buffer for buffering the shock when the rack end of the stopper fixed to the rack shaft reciprocally movable relative to the rack housing collides with the end surface of the rack housing. A device (hereinafter referred to as “buffer device” where appropriate) is provided. In this shock absorber, before the rack end collides with the end surface of the rack housing, a rack stroke end shock absorber (hereinafter referred to as “buffer body”) that absorbs the impact by being sandwiched between the two is provided. With reference to FIG.5 and FIG.6, the typical example of the buffer device which concerns on a prior art example is demonstrated.

  FIG. 5 is a schematic cross-sectional view of a rack stroke end shock absorber according to Conventional Example 1. As shown in the drawing, a ball joint 50 as a stopper is fixed to a rack shaft 40 that can reciprocate relative to the rack housing 30. In this conventional example, a buffer body 100 is provided at the end of the rack shaft 40 on the side fixed to the ball joint 50. Thus, when the rack shaft 40 moves to the stroke end, the shock absorber 100 is provided in the rack housing 30 before the rack end 51 of the ball joint 50 collides with the end surface 32 of the rack housing 30. The impact is absorbed by colliding with the notch 33.

  FIG. 6 is a schematic cross-sectional view of a rack stroke end shock absorber according to Conventional Example 2. In the case of this conventional example, the buffer body 200 is provided along the outer peripheral surface of the annular notch 33 provided in the rack housing 30. In this conventional example, when the rack shaft 40 moves to the stroke end, the rack end 51 of the ball joint 50 collides with the buffer body 200 before colliding with the end surface 32 of the rack housing 30. Shock is absorbed.

  In the case of Conventional Example 1, the shock absorber 100 is fixed in a state of being positioned on the rack shaft 40 by the tightening force on the inner peripheral side of the shock absorber 100 that is an annular elastic body. Therefore, there is a problem that it is difficult to set a tightening allowance of the buffer body 100 in order to achieve both mounting properties to the rack shaft 40 and prevention of falling off from the rack shaft 40. In addition, since the buffer body 100 is positioned and fixed with a tightening force according to the tightening allowance, there is also a problem that the buffer body 100 is likely to drop off from the rack shaft 40 due to a decrease in the tightening force due to deterioration over time. Further, for example, a chamfer 110 needs to be provided in the vicinity of the inner peripheral edge of the shock absorber 100 so that the shock absorber 100 does not break by colliding with the edge portion of the opening edge of the insertion hole 31 in the rack housing 30. . Therefore, there is a problem that the degree of freedom in design is small and the pressure receiving area of the buffer body 100 cannot be widened.

  In the case of Conventional Example 2, the buffer body 200 is fixed in a state of being positioned at the notch 33 by the tightening force on the outer peripheral side of the buffer body 200 which is an annular elastic body. Therefore, in the case of the conventional example 2, as in the case of the conventional example 1, it is difficult to set the tightening allowance of the buffer body 200, and there is a problem that the tightening force is lowered due to deterioration over time. Further, for example, a chamfer 210 is provided near the outer peripheral edge of the shock absorber 200 so that the vicinity of the outer periphery of the shock absorber 200 is not sandwiched between the ball joint 50 and the end surface 32 of the rack housing 30 and is not damaged. There is a need. Therefore, there is also a problem that the degree of freedom in design is small as in the case of Conventional Example 1.

Japanese Patent Laid-Open No. 08-133102

  An object of the present invention is to provide a rack stroke end shock absorber and a rack stroke end shock absorber that are easy to mount, have excellent mounting stability, and have a high degree of design freedom.

  The present invention employs the following means in order to solve the above problems.

That is, the rack stroke end shock absorber of the present invention is
In a rack stroke end shock absorber that cushions an impact when a rack end of a stopper fixed to a rack shaft that can reciprocate with respect to the rack housing collides with an end surface of the rack housing.
An end portion on the rack end side of the rack housing is provided with an annular cutout portion formed along the edge of the opening portion of the insertion hole through which the rack shaft is inserted,
An impact absorbing portion that absorbs an impact by being sandwiched between a surface facing the rack end at the notch and the rack end;
An insertion part that is inserted into the insertion hole further than the notch,
With
The insertion portion is provided with an engagement protrusion that engages with an engagement recess formed on an inner peripheral surface of the insertion hole.

The rack stroke end shock absorber of the present invention is
A rack housing;
A rack shaft reciprocally movable with respect to the rack housing;
A rack stroke end buffer for buffering an impact when a rack end of a stopper fixed to the rack shaft collides with an end surface of the rack housing;
A rack stroke end shock absorber comprising:
The rack housing is provided with an annular notch formed at the end on the rack end side along the edge of the opening of the insertion hole through which the rack shaft is inserted.
The rack stroke end shock absorber is
An impact absorbing portion that absorbs an impact by being sandwiched between a surface facing the rack end at the notch and the rack end;
An insertion part that is inserted into the insertion hole further than the notch,
With
The insertion portion is provided with an engagement protrusion that engages with an engagement recess formed on an inner peripheral surface of the insertion hole.

According to the present invention, the rack stroke end shock absorber is mounted (positioned) on the rack housing by engaging the engagement protrusion with the engagement recess formed in the inner peripheral surface of the insertion hole provided in the rack housing. Fixed). Thus, there is no problem that it is difficult to set the tightening allowance in order to achieve both mountability and prevention of falling-off as in the case where the buffer body is positioned and fixed by setting the tightening allowance. Also, when positioning and fixing with a tightening force as in the past, the buffer body must be inserted with the buffer body compressed as much as the tightening allowance, so the force when mounting the buffer body is large. On the other hand, according to the present invention, it is possible to set a small force when the shock absorber is mounted because no fastening margin is required. In addition, since there is no problem of a decrease in tightening force due to deterioration over time, the wearing state can be stabilized over a long period of time. Furthermore, in the case of the present invention, since the impact absorbing portion that absorbs the impact and the insertion portion for positioning and fixing the shock absorber are separated, the degree of freedom in designing the impact absorbing portion can be increased.

  Here, the inner diameter of the impact absorbing portion may be set to be larger than the outer diameter of the main body portion of the insertion portion.

  By doing so, even if the impact absorbing portion is compressed and deformed by impact, the influence on the insertion portion can be suppressed, and the adverse effect on the mounting state of the shock absorber can be suppressed.

  As described above, according to the present invention, it is possible to facilitate mounting, improve mounting stability, and increase design freedom.

1 is a schematic sectional view (partially broken sectional view) of a rack stroke end shock absorber according to a first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view (partially broken cross-sectional view) of the rack stroke end buffer according to the first embodiment of the present invention. FIG. 3 is a schematic sectional view (partially broken sectional view) of the rack stroke end shock absorber according to the second embodiment of the present invention. FIG. 4 is a schematic cross-sectional view (partially broken cross-sectional view) of a rack stroke end shock absorber according to Embodiment 2 of the present invention. FIG. 5 is a schematic sectional view (partially broken sectional view) of the rack stroke end shock absorber according to Conventional Example 1. FIG. 6 is a schematic cross-sectional view (partially cut-away cross-sectional view) of a rack stroke end shock absorber according to Conventional Example 2. FIG.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be exemplarily described in detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. .

Example 1
A rack stroke end shock absorber and a rack stroke end shock absorber according to a first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

<Rack stroke end shock absorber>
In particular, a rack stroke end shock absorber according to Embodiment 1 of the present invention will be described with reference to FIG.

2. Description of the Related Art As a steering mechanism for an automobile, a rack and pinion type steering mechanism that converts a rotational motion into a linear motion by engaging a rack with a pinion that rotates as a handle rotates is known. This steering mechanism is configured such that the stroke end (movement end position) is determined by the rack end 51 colliding with the end surface 32 of the rack housing 30. The steering mechanism is provided with a rack stroke end shock absorber (hereinafter referred to as a “buffer device”) in order to buffer an impact when the rack end 51 collides with the end surface 32 of the rack housing 30. . When the handle is rotated to the maximum steering angle, the rack end 51 collides with the end surface 32 of the rack housing 30.

  As shown in FIG. 1, the shock absorber according to this embodiment includes a metal rack housing 30, a rack shaft 40 that is reciprocally movable in an insertion hole 31 formed in the rack housing 30, and a rack shaft. A metal ball joint 50 that also functions as a stopper fixed to 40 and a rack stroke end buffer (hereinafter referred to as “buffer 10”).

  The rack housing 30 includes an insertion hole 31 through which the rack shaft 40 is inserted, an annular notch 33 provided at an end on the rack end 51 side, and an annular engagement formed on the inner peripheral surface of the insertion hole 31. And a concavity 34. The annular notch 33 is formed along the edge of the opening of the insertion hole 31. Then, an annular buffer body 10 made of an elastic body such as rubber is attached to the notch 33.

  In the ball joint 50, a ball receiving portion 52 is formed on the side opposite to the rack end 51, which is a surface that collides with the end surface 32 of the rack housing 30. A ball portion 60 provided at the tip of the tie rod 70 is fitted to the ball receiving portion 52. As a result, the tie rod 70 can swing with respect to the ball joint 50.

<Rack stroke end shock absorber>
In particular, the rack stroke end buffer (buffer 10) will be described in more detail with reference to FIG. The shock absorber 10 is composed of an annular elastic body, and is composed of an impact absorbing portion 11 and an insertion portion 12, and is arranged so that the impact absorbing portion 11 is on the rack end 51 side. The outer diameter of the outer peripheral surface of the shock absorbing portion 11 is configured to be larger than the outer diameter of the outer peripheral surface of the insertion portion 12. An annular engagement protrusion 13 protruding outward is provided at the end of the insertion part 12 opposite to the shock absorbing part 11.

  When the shock absorber 10 configured as described above is mounted on the rack housing 30, the insertion portion 12 is placed inside the insertion hole 31 of the rack housing 30 until the engagement protrusion 13 engages with the engagement recess 34. Insert into. As a result, the end surface on the insertion portion 12 side of the shock absorbing portion 11 is in close contact with the surface of the cutout portion 33 facing the rack end 51, and the shock absorber 10 is mounted on the rack housing 30 (fixed in a positioned state). Is done. At this time, the end surface on the rack end 51 side in the shock absorbing portion 11 is in a state of protruding to the rack end 51 side from the end surface 32 of the rack housing 30 (see FIG. 1). Therefore, when the rack shaft 40 moves to the stroke end, the rack end 51 of the ball joint 50 collides with the impact absorbing portion 11 before colliding with the end surface 32 of the rack housing 30. As a result, the shock absorbing unit 11 absorbs the shock by being sandwiched between the rack end 51 and the surface facing the rack end 51 in the notch 33.

<Excellent point of rack stroke end buffer according to this embodiment>
As described above, according to the present embodiment, the shock absorber 10 is engaged by engaging the engagement protrusion 13 with the engagement recess 34 formed on the inner peripheral surface of the insertion hole 31 provided in the rack housing 30. Can be mounted (positioned and fixed) on the rack housing 30. Thus, there is no problem that it is difficult to set the tightening allowance in order to achieve both mountability and prevention of falling-off as in the case where the buffer body is positioned and fixed by setting the tightening allowance.

Further, in the case of the shock absorber 10 according to the present embodiment, the tightening allowance for positioning and fixing is not necessary, so that the force when attaching the shock absorber 10 can be set small. That is, the outer diameter of the main body portion of the insertion portion 12 is set to be approximately the same as the inner diameter of the insertion hole 31 provided in the rack housing 30, and there is no need to provide a tightening allowance. However, a tightening margin may be provided so that the insertion force does not increase. Further, the engaging protrusion 13 is compressed or deformed inward when the insertion portion 12 is inserted. However, the outer diameter of the engaging protrusion 13 does not need to be so large, and if it is partially protruded. Good. Thus, in the case of the present embodiment, by adopting a configuration in which the buffer protrusion 10 is mounted on the rack housing 30 by engaging the engagement protrusion 13 with the engagement recess 34, the buffer body is tightened. Compared with the case of providing, the force at the time of mounting can be made sufficiently small. Therefore, the mounting property of the buffer body 10 can be improved.

  Further, in the case of the shock absorber 10 according to the present embodiment, there is no problem of a decrease in tightening force due to deterioration over time, so that the mounting state can be stabilized over a long period of time.

  Further, in the case of the shock absorber 10 according to the present embodiment, the shock absorbing portion 11 that absorbs the shock and the insertion portion 12 for positioning and fixing the shock absorber 10 are separated. The degree of freedom can be increased. For example, as shown in FIG. 1, a gap is formed between the inner peripheral surface of the shock absorber 11 and the outer peripheral surface of the rack shaft 40, and the outer peripheral surface of the shock absorber 11 and the inner peripheral surface of the notch 33. The dimension can be set so that there is a gap between the two. By doing so, it is possible to suppress damage due to pinching or the like between the two members without providing chamfering as shown in the conventional examples 1 and 2. Moreover, since it is not necessary to provide chamfering, there is an advantage that the pressure receiving area of the buffer body 10 can be easily set wide.

(Example 2)
3 and 4 show a second embodiment of the present invention. In the first embodiment, the configuration in which the inner diameter of the shock absorbing portion and the inner diameter of the insertion portion are the same is shown. However, in this embodiment, the inner diameter of the shock absorbing portion is larger than the outer diameter of the main body portion of the insertion portion. The configuration when the value is also set larger is shown. Since other configurations and operations are the same as those in the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the shock absorber according to the present embodiment, only the structure of the rack stroke end shock absorber (hereinafter referred to as “buffer body 20”) is different from the structure of the first embodiment. Therefore, descriptions of the other rack housing 30, the rack shaft 40, the ball joint 50, and the like will be omitted as appropriate.

  Similarly to the case of the first embodiment, the shock absorber 20 according to the present embodiment is also configured by an annular elastic body, and includes a shock absorbing portion 21 and an insertion portion 22. It arrange | positions so that it may become the rack end 51 side. Further, the outer diameter of the outer peripheral surface of the shock absorbing portion 21 is configured to be larger than the outer diameter of the outer peripheral surface of the insertion portion 22. An annular engagement protrusion 23 that protrudes outward is provided at an end of the insertion portion 22 opposite to the shock absorbing portion 21. Here, the mounting method of the shock absorber 20 to the rack housing 30 is the same as in the case of the first embodiment, and the description thereof will be omitted.

  In the case of the shock absorber 20 according to the present embodiment, the inner diameter D1 of the shock absorbing portion 21 is set to be larger than the outer diameter D2 of the main body portion (the portion excluding the engagement protrusion 23) of the insertion portion 22. .

  Also in the case of the shock absorber 20 according to the present embodiment configured as described above, as in the case of the first embodiment, when the rack shaft 40 moves to the stroke end, the rack end 51 of the ball joint 50 is used. Before impacting the end surface 32 of the rack housing 30, the impact impacting portion 21 is impacted. Thereby, the impact absorbing portion 21 absorbs the impact by being sandwiched between the rack end 51 and the surface of the notch 33 facing the rack end 51.

At this time, the impact absorbing portion 21 is compressed and deformed by being sandwiched between the two. Here, in the case of the present embodiment, as described above, the inner diameter D1 of the shock absorbing portion 21 is set larger than the outer diameter D2 of the main body portion of the insertion portion 22. Therefore, even if the shock absorbing portion 21 is compressed and deformed, the influence on the insertion portion 22 can be suppressed, and the adverse effect on the mounting state of the shock absorber 20 can be suppressed. That is, even if the shock absorbing portion 21 is compressed and deformed, the engagement protrusion 23 hardly deforms, so that the engagement protrusion 23 can be prevented from being detached from the engagement recess 34.

  As described above, in the shock absorber 20 according to the present embodiment, the same effect as that of the shock absorber 10 in the first embodiment can be obtained, and in addition, the engagement protrusion 23 accompanying the compression deformation of the shock absorbing portion 21. An effect of suppressing the adverse effect on the engagement state between the engagement recess 34 and the engagement recess 34 can be obtained.

(Other)
In the above-described embodiment, the case where the engagement protrusion provided on the buffer body is formed in an annular shape has been described. That is, as long as the engagement recess 34 provided in the rack housing 30 can be sufficiently engaged, a configuration in which at least one partial engagement protrusion is provided instead of the annular engagement protrusion is adopted. May be. Moreover, in the said Example, the structure which forms the engagement recessed part 34 by making a part of opening part vicinity (notch part 33) of the insertion hole 31 in the rack housing 30 protrude partially inside. Adopted. However, the configuration for forming the engaging recess is not limited to such a configuration. For example, a configuration in which a part of the inner peripheral surface of the insertion hole 31 is partially recessed may be employed. Moreover, when employ | adopting the structure which provides an engagement protrusion partially as mentioned above, the structure which forms not only cyclic | annular form but also about an engagement recessed part can also be employ | adopted. However, by adopting a configuration in which both are annular or only the engagement recess is annular, the position in the rotational direction of the buffer body is not restricted, and thus the wearability is excellent. In the second embodiment, as is clear from FIG. 4, the inner diameter D <b> 1 of the impact absorbing portion 21 is set larger than the outer diameter of the engagement protrusion 23. However, if the relationship of D1> D2 is established, the deformation of the engaging protrusion 23 accompanying the compression deformation of the shock absorbing portion 21 can be suppressed, so that the outer diameter of the engaging protrusion 23 is larger than the inner diameter D1 of the shock absorbing portion 21. It doesn't matter.

DESCRIPTION OF SYMBOLS 10 Buffer 11 Shock absorption part 12 Insertion part 13 Engagement protrusion 20 Buffer 21 Shock absorption part 22 Insertion part 23 Engagement protrusion 30 Rack housing 31 Insertion hole 32 End surface 33 Notch part 34 Engagement recessed part 40 Rack shaft 50 Ball joint 51 Rack end 52 Sphere receiving part 60 Sphere part 70 Tie rod

Claims (4)

In a rack stroke end shock absorber that cushions an impact when a rack end of a stopper fixed to a rack shaft that can reciprocate with respect to the rack housing collides with an end surface of the rack housing.
An end portion on the rack end side of the rack housing is provided with an annular cutout portion formed along the edge of the opening portion of the insertion hole through which the rack shaft is inserted,
An impact absorbing portion that absorbs an impact by being sandwiched between a surface facing the rack end at the notch and the rack end;
An insertion part that is inserted into the insertion hole further than the notch,
With
The rack stroke end shock absorber according to claim 1, wherein the insertion portion is provided with an engagement protrusion that engages with an engagement recess formed in an inner peripheral surface of the insertion hole.   The rack stroke end shock absorber according to claim 1, wherein an inner diameter of the shock absorbing portion is set to be larger than an outer diameter of a main body portion of the insertion portion. A rack housing;
A rack shaft reciprocally movable with respect to the rack housing;
A rack stroke end buffer for buffering an impact when a rack end of a stopper fixed to the rack shaft collides with an end surface of the rack housing;
A rack stroke end shock absorber comprising:
The rack housing is provided with an annular notch formed at the end on the rack end side along the edge of the opening of the insertion hole through which the rack shaft is inserted.
The rack stroke end shock absorber is
An impact absorbing portion that absorbs an impact by being sandwiched between a surface facing the rack end at the notch and the rack end;
An insertion part that is inserted into the insertion hole further than the notch,
With
The rack stroke end shock absorber according to claim 1, wherein the insertion portion is provided with an engagement protrusion that engages with an engagement recess formed on an inner peripheral surface of the insertion hole.   The rack stroke end shock absorber according to claim 3, wherein an inner diameter of the shock absorbing portion is set larger than an outer diameter of a main body portion of the insertion portion.

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