JP2008189214A - Shock-absorber for rack stroke end - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shock-absorber for a rack stroke end which is less limited in installation space and providing excellent shock-absorbing effect. <P>SOLUTION: A flange-shaped part 32 is provided on a rack end stud 30, and a rack boot 40 is provided between the flange-shaped part 32 and a fore end cylindrical part 22 of a rack housing 20. Shock-absorbing elastic parts 41a, 41b are integrated on both ends of the rack boot 40. During the full stroke, the shock-absorbing elastic parts 41a, 41b of the rack boot 40 are held between the flange-shaped part 31 of the rack end stud 30 and the fore end cylindrical part 22 of the rack housing 20 for absorbing shocks. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an impact mitigation device for a rack stroke end that mitigates an impact that occurs when a rack shaft that moves in the vehicle width direction by a steering operation reaches a stroke end position.

  2. Description of the Related Art Conventionally, in a steering apparatus for a vehicle, a rotational movement of a steering shaft connected to a steering handle is converted into an axial movement of the rack shaft by a rack and pinion mechanism, and via tie rods connected to both ends of the rack shaft. The wheel is steered by applying a steering force to the wheel knuckle. In such a steering device, the stroke amount of the rack shaft is regulated. For example, in the apparatus proposed in Patent Document 1, the stroke amount is regulated by abutment between a ball joint housing fixed to both ends of the rack shaft and a rack housing that houses the rack shaft. Concave portions extending in the axial direction are formed in the opening portions at both ends of the rack housing, and when the rack shaft moves in the vehicle width direction, the ball joint housing provided at the tip of the rack shaft is movable in the concave portion. . When the steering handle is steered to a predetermined angle, the end surface of the recess and the housing of the ball joint come into contact with each other to restrict the stroke amount of the rack shaft. The ball joint is provided at one end of the tie rod, and slidably connects the tie rod to the tip of the rack shaft.

Further, in the apparatus of Patent Document 1, in order to mitigate the impact that occurs when the rack shaft reaches the stroke end position, an impact mitigating member is provided at the abutting portion between the ball joint housing and the concave end surface of the rack housing. ing. This impact mitigating member is formed by attaching an elastic body to the outer peripheral side surface of a ring-shaped metal member, and is fixed to the ball joint housing at a position facing the concave end surface of the rack housing.
JP 2006-1510 A

  However, as described above, in the configuration in which the impact mitigating member is provided at the abutting portion between the ball joint housing and the concave end surface of the rack housing, the installation space for the impact mitigating member is greatly limited, and a sufficient volume of the elastic body is secured. Can not. As a result, a good impact / sound reduction effect cannot be obtained.

  For example, when the restrictions in the rack axial direction are described, the rack stroke is reduced by the thickness of the impact relaxation member in the axial direction. The only way to ensure the rack stroke is to cut the concave portion of the rack housing inward in the vehicle width direction by the thickness of the impact mitigating member, or to shift the center of the ball joint outward in the vehicle width direction. Affects sex.

  Further, regarding the radial restrictions, the inner diameter of the impact mitigating member is restricted by the rack shaft diameter, and the outer diameter of the impact mitigating member is restricted by the concave inner diameter of the rack housing, the inner diameter of the rack boot, and the outer diameter of the ball joint housing. . That is, the ring-shaped impact mitigating member must have an inner diameter larger than the rack shaft diameter and an outer diameter smaller than the concave inner diameter of the rack housing, the rack boot inner diameter, and the ball joint housing outer diameter. On the other hand, the rack shaft cannot be reduced in diameter due to the strength condition, and if the configuration that restricts the outer diameter of the impact mitigating member is increased, the entire steering device is increased in size.

  The present invention has been made to address the above-described problems, and an object of the present invention is to provide an impact mitigation device at the rack stroke end in which there are few restrictions on installation space and a good impact mitigation effect can be obtained.

  In order to achieve the above object, the present invention is characterized in that a rack shaft that is displaced in the axial direction in accordance with a steering operation, a fixed to the vehicle body, the tip of the rack shaft is exposed, and the rack shaft is moved in the axial direction. A rack housing that is displaceably accommodated, a connecting shaft that is swingably connected to a tip of the rack shaft, and that transmits an operating force of the rack shaft to a wheel, and one end connected to the rack housing and the other end connected to the rack housing A rack boot connected to a shaft and covering the exposed portion of the end of the rack shaft and a connecting portion between the rack shaft and the connecting shaft with a bellows tube; and a stroke end position that restricts movement of the rack shaft in the axial direction In a rack stroke end impact mitigation device that is provided in a steering device having a stopper for setting the stroke, and that mitigates an impact when the rack shaft reaches the stroke end position. And an elastic body for shock relaxation that is sandwiched between the connecting shaft and the rack housing when the rack shaft reaches the stroke end position at at least one end of the rack boot. It is because it was formed integrally.

  According to the present invention, the rack shaft is displaced in the axial direction by the steering operation and the wheel is steered through the connecting shaft, but the stroke end position (maximum displacement position) is regulated by the stopper. When the rack shaft reaches the stroke end position, an impact is generated by the stopper. In the present invention, the impact is mitigated by an impact mitigating elastic body portion formed on at least one end of the rack boot. The rack boot covers the exposed end of the rack shaft and the connecting portion between the rack shaft and the connecting shaft with a bellows tube to prevent entry of dust, water, etc. One end is connected to the rack housing and the other end is connected to the connecting shaft. Connected to. In the present invention, an impact relaxation elastic body is integrally formed at the end of the rack boot, and when the rack shaft reaches the stroke end position, that is, immediately before the rack shaft reaches the stroke end position, the shock relaxation elastic body. The part is sandwiched between the connecting shaft and the rack housing to reduce the impact.

  For this reason, it is not necessary to newly provide a separate part as an impact reducing member, and the manufacturing cost can be suppressed. In addition, the diameter of the impact relaxation elastic body can be increased, and a wide pressure receiving area can be secured. For this reason, good impact relaxation performance can be obtained.

  Another feature of the present invention is that the connecting shaft is formed with an opposing wall facing the front end tubular portion of the rack housing in the rack axial direction, and shock mitigation provided at at least one end of the rack boot. The elastic body portion is provided at an end portion of the front end tubular portion of the rack housing or an opposing wall formed on the connecting shaft, and when the rack shaft reaches the stroke end position, the elastic shaft portion is opposed to the connecting shaft. The impact is mitigated by being sandwiched between the wall and the cylindrical end portion of the rack housing.

  According to the present invention, the connecting shaft is formed with the opposing cylindrical wall facing the tip cylindrical portion of the rack housing in the rack axis direction, and when the rack shaft reaches the stroke end position, the shock absorbing elastic body portion is connected to the connecting shaft. It is sandwiched between the opposing wall and the tip cylindrical portion of the rack housing to reduce the impact. For this reason, the diameter of the elastic body part for shock relaxation can be made substantially equal to the diameter of the tip cylindrical part of the rack housing, and a wide pressure receiving area can be secured. In addition, there are few restrictions on the space for mounting the shock absorbing elastic body, and good shock absorbing performance can be obtained without problems such as effects on vehicle motion performance, insufficient strength of the rack shaft, and enlargement of the rack housing. .

  According to another aspect of the present invention, the rack boot includes an elastic body portion for shock reduction integrally formed at both ends, and one elastic body is provided at an end portion of the tip cylindrical portion of the rack housing. The other impact relaxation elastic part is provided on the opposing wall formed on the connecting shaft.

  In this invention, since the elastic body for shock relaxation is integrally formed at both ends of the rack boot, even if the rack shaft reaches the stroke end position and the bellows tube is clamped, the bellows tube is shock-relieved on both sides thereof. It will be pinched by the elastic body part. For this reason, the bellows tube can be protected, and the durability of the rack boot can be ensured.

  Another feature of the present invention is that the bellows bending portion of the bellows tube of the rack boot is configured such that the impact relaxation elastic body portion between the connecting shaft and the rack housing when the rack shaft reaches a stroke end position. Is provided at a position deviating from the region receiving the impact load to the inside or the outside in the radial direction of the rack shaft.

  According to this invention, even when the rack shaft reaches the stroke end position, the bellows bending portion of the bellows tube of the rack boot is not sandwiched between the elastic bodies for shock relaxation, so that a large load is applied to the bellows bending portion. It does not take. Therefore, breakage of the bellows bent portion is suppressed, and the durability of the rack boot can be improved.

  According to another feature of the present invention, the stopper includes a ring-shaped step provided in the vehicle width inner side with respect to the end of the end tubular portion of the rack housing, and the stopper fixed to the end of the rack shaft and swings the connecting shaft. The movement of the rack shaft in the axial direction is restricted by contact with a casing of a ball joint that is movably connected.

  According to the present invention, it is possible to easily relieve the impact by using the impact relieving elastic body portion provided at the end portion of the rack boot while using the conventional stopper structure as it is.

  DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment according to a rack stroke end impact mitigating device of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of an impact mitigation device at a rack stroke end as an embodiment. This impact mitigation device is provided in a rack and pinion type steering device of a vehicle. As shown schematically in FIG. 7, this steering device converts the rotational motion around the axis of the steering shaft 2 that rotates by the operation of the steering handle 1 into linear motion in the axial direction of the rack shaft 10 via the pinion gear 3, The wheels (not shown) are steered by the linear motion of the rack shaft 10.

  The rack shaft 10 is housed in a rack housing 20 fixed to the vehicle body and formed in the vehicle width direction so as to be movable in the axial direction (vehicle width direction). A rack end stud 30 is swingably connected to both ends of the rack shaft 10, and a rack boot 40 is provided so as to cover a connecting portion with the rack end stud 30. In the rack housing 20, an actuator 50 (a reduction gear using an electric motor and a ball screw) as a power steering device is disposed coaxially with the rack shaft 10. The actuator of the power steering device may be provided on the steering shaft side or may not be mounted.

  Hereinafter, the stopper mechanism and the impact mitigation device provided on both the left and right sides of the rack shaft 10 will be described.

As shown in FIGS. 1 and 2, both ends of the rack housing 20 are opened, and the tips (both ends) of the rack shaft 10 are exposed from the opening 21. A rack end socket 11 is fixed to the end of the rack shaft 10 by screw fastening. In the rack end socket 11, a ball joint 31 provided at one end of the rack end stud 30 is housed so as to be swingable. The rack end stud 30 constitutes a connecting shaft that connects a knuckle (not shown) fixed to a wheel and the rack shaft 10, and a ball joint 31 provided at one end thereof is accommodated in the rack end socket 11. The rack shaft 10 is swingably connected.
The rack end stud 30 in the present embodiment corresponds to the connecting shaft in the present invention. The connecting shaft may be composed of a plurality of members to connect the rack shaft 10 and the knuckle. Further, the rack end socket 11 in the present embodiment corresponds to a ball joint casing in the present invention.

  The rack end socket 11 has an outer diameter that is larger than the outer diameter of the front end of the rack shaft 10, and a ring-shaped flat surface 12 facing inward in the vehicle width direction is formed around a fastening portion with the rack shaft 10. The The rack end stud 30 is a columnar shaft body, and a hook-shaped portion 32 extending radially outward is formed at an intermediate position in the axial direction. The bowl-shaped portion 32 is formed in a disc shape so that the outer diameter thereof is substantially the same as the outer diameter of the end of the rack housing 20. The hook-shaped portion 32 corresponds to the facing wall in the present invention. In addition, this hook-shaped part 32 may not be integrally formed from the rack end stud 30, but may be formed integrally by attaching another part.

A ring-shaped recess 33 for attaching the rack boot 40 is formed on the radially outer front end portion of the bowl-shaped portion 32 on the side facing the front end cylindrical portion 22 of the rack housing 20.
On the other hand, a ring-shaped recess 23 for attaching the rack boot 40 is formed on the cylindrical end portion 22 of the rack housing 20 so as to face the flange-shaped portion 32 of the rack end stud 30.

  The opening 21 at the front end (both ends) of the rack housing 20 is formed by an opening recess 24 having an enlarged inner diameter extending a predetermined length in the axial direction. The opening recess 24 has an inner diameter larger than the outer diameter of the rack end socket 11, and when the rack shaft 10 is moved in the axial direction by a handle operation, it is a region where the rack end socket 11 can move accordingly. . The portion recessed from the opening 21 of the rack housing 20 in the vehicle width inward direction by a predetermined length is the end of the opening recess 24, and the inner diameter of the housing is smaller than the outer diameter of the rack end socket 11 at the depth. Therefore, a ring-shaped step 25 is formed at the end of the opening recess 24. The ring-shaped step portion 25 is formed with a ring-shaped flat surface 26 that extends in the vehicle width outward direction. Accordingly, when the steering handle 1 is rotated to a predetermined angle, the ring-shaped flat surface 12 of the rack end socket 11 provided at the tip of the rack shaft 10 becomes a ring-shaped flat surface 26 formed on the ring-shaped step portion 25 in the rack housing 20. At the end, the movement of the rack shaft 10 is restricted. Hereinafter, the state in which the movement of the rack shaft 10 is regulated in this way is referred to as a full stroke.

  In this manner, the steering device moves the rack shaft 10 by the contact between the ring-shaped flat surface 12 of the rack end socket 11 facing the inner side of the vehicle width and the ring-shaped flat surface 26 of the rack housing 20 facing the outer side of the vehicle width. It constitutes a stopper that regulates Therefore, the position of the rack shaft 10 when both the ring-shaped flat surfaces 12 and 26 abut is the stroke end position.

  The rack boot 40 is made of rubber or elastic synthetic resin having ring-shaped impact-relieving elastic body portions 41a and 41b provided at both ends and a bellows tube 42 provided between both impact-relieving elastic body portions 41a and 41b. Are integrally formed. In the rack boot 40, one impact relaxation elastic body portion 41a (hereinafter simply referred to as an elastic body portion 41a) is fitted into a ring-shaped recess portion 23 formed in the front end tubular portion 22 of the rack housing 20, and the other shock relaxation elastic body portion 41a. An elastic body portion 41b (hereinafter simply referred to as an elastic body portion 41b) is fitted into a ring-shaped recess 33 formed in the flange-shaped portion 32 of the rack end stud 30, and the outer periphery of each elastic body portion 41a, 41b is surrounded by bands 43a, 43b. Mounted by tightening radially inward.

  The elastic body portion 41 a fixed to the tip cylindrical portion 22 of the rack housing 20 is provided so as to protrude outward in the vehicle width direction from the ring-shaped recess portion 23, and is fixed to the flange-shaped portion 32 of the rack end stud 30. The portion 41b is provided so as to protrude from the ring-shaped recess 33 toward the vehicle width inner side. The left and right elastic body portions 41a and 41b are formed in a ring shape having substantially the same shape as viewed in the axial direction of the rack shaft 10, and are positioned on the same axis line and face each other when the rack shaft 10 is at the stroke end position. It is like that.

  In the rack boot 40, when the rack shaft 10 reaches a position slightly in front of the stroke end position, the two elastic body portions 41a and 41b are formed so that the tip cylindrical portion 22 of the rack housing 20 and the hook-shaped portion of the rack end stud 30 are provided. 32 and is elastically deformed. This can be implemented by adjusting the formation position in the axial direction of the hook-shaped portion 32 of the rack end stud 30, the thickness (axial dimension) of the elastic body portions 41 a and 41 b, and the like. Thereby, even when the steering handle 1 is vigorously rotated and the rack shaft 10 reaches the stroke end position, the load is shared by the elastic body portions 41a and 41b and the stoppers (two ring-shaped flat surfaces 12, The impact acting on the abutting portion 26) can be reduced. Therefore, the impact mitigation device in this embodiment includes the rack boot 40, the hook-shaped portion 32 formed on the rack end stud 30 that clamps the elastic body portions 41 a and 41 b of the rack boot 40, and the tip cylindrical portion 22 of the rack housing 20. It can be said that it is composed of

  Further, as shown in FIG. 2, the bellows tube 42 of the rack boot 40 has an elastic bellows bent portion 44 (outer diameter side bent portion 44o, inner diameter side bent portion 44i) when the rack shaft 10 is at the stroke end position. It is provided at a position outside the region sandwiched between the body parts 41a and 41b.

Here, when the rack shaft 10 is at the stroke end position, the outer diameter of the bellows tube 42 is Ro, the inner diameter of the bellows tube 42 is Ri, the outer diameter of the elastic body portions 41a and 41b receiving the impact load is ro, elastic Assuming that the inner diameter of the portion receiving the impact load of the body parts 41a and 41b is ri, in this embodiment, the following relationship is set.
Ro> ro and Ri <ri

  For this reason, even when the rack shaft 10 reaches the stroke end position, the bellows bending portion 44 of the bellows tube 42 of the rack boot 40 is not sandwiched between the elastic body portions 41a and 41b. No load is applied. Therefore, breakage of the bellows bent portion 44 is suppressed, and the durability of the rack boot 40 can be improved.

Next, the operation of the impact mitigation device in the steering device of this embodiment will be described.
As shown in FIG. 1, when the steering handle 1 is not operated at full stroke (for example, in the neutral position), the rack end socket 11 is not in contact with the ring-shaped step portion 25 of the rack housing 20. The movement of 10 is not regulated. At this time, the rack boot 40 covers the tip exposed portion of the rack shaft 10 and the connecting portion between the rack shaft 10 and the rack end stud 30 to prevent entry of dust, water, and the like. Further, the rack boot 40 does not interfere with the operation of the steering handle 1 due to its flexibility.

  When the driver turns the steering handle 1 greatly, the rack shaft 10 moves greatly in the axial direction, and the rack end socket 11 hits the ring-shaped step portion 25 formed in the rack housing 20. That is, the ring-shaped plane 12 of the rack end socket 11 abuts against the ring-shaped plane 26 of the ring-shaped step portion 25. Thereby, the movement of the rack shaft 10 is regulated.

  In this case, immediately before the rack shaft 10 reaches the stroke end position, the elastic body portions 41 a and 41 b formed at both ends of the rack boot 40 abut each other with the bellows tube 42 interposed therebetween. In other words, the rack boot 40 is pinched in the axial direction by the tip cylindrical portion 22 of the rack housing 20 and the flange portion 32 of the rack end stud 30. As a result, the elastic body portions 41a and 41b are elastically deformed due to an axial load. The rack shaft 10 further moves in the axial direction due to elastic deformation of the elastic body portions 41 a and 41 b, and stops when the rack end socket 11 hits the ring-shaped step portion 25 formed in the rack housing 20. Therefore, the impact load at the stroke end position can be reduced by the elastic body portions 41 a and 41 b of the rack boot 40.

  According to the impact mitigation device at the rack stroke end according to the embodiment described above, the elastic body portion 41a absorbs the impact load during the full stroke operation by the elastic body portions 41a and 41b formed at both ends of the rack boot 40. , 41b can be made as large as the diameter of the tip cylindrical portion 22 of the rack housing 20, and a large pressure receiving area can be secured. In addition, the thickness of the elastic body portions 41a and 41b in the axial direction can be sufficiently secured. Therefore, there are few restrictions on the installation space of the impact mitigating member as in the conventional device, and good impact mitigating performance can be obtained without degrading or increasing the performance of the steering device. In particular, when a large assist torque is applied by the operation of the power steering device or when a fast steering operation is performed, the impact per stopper may be increased, but in this embodiment, such an impact is improved. Can be relaxed.

  Further, since the elastic body portions 41a and 41b are integrally formed at both ends of the rack boot 40, the cost can be reduced without increasing the number of parts. Furthermore, since the bellows bending portion 44 of the bellows tube 42 is provided at a position not sandwiched between the elastic body portions 41a and 41b, the bellows bending portion 44 is prevented from being damaged and the durability of the rack boot 40 can be improved. . Further, since the elastic body portions 41a and 41b are provided at both ends of the rack boot 40, even if the surface of the bellows tube 42 excluding the bellows bent portion 44 is sandwiched between the elastic body portions 41a and 41b, it is sandwiched between the metal surfaces. Therefore, good durability can be obtained.

Next, a modified example of the impact relaxation device will be described.
In the above-described shock absorbing device, the elastic body portions 41a and 41b are integrally formed at both ends of the rack boot 40. However, as shown in FIGS. 3 and 4, the rack boot 401 having the elastic body portion 41a integrally formed only on one side is provided. It may be used. In this case, the elastic body portion 41a is clamped between the rack housing 20 and the rack end stud 30 to reduce the impact. In this modification, the elastic body portion 41a is provided on the rack housing 20 side, but may be provided on the rack end stud 30 side. Since the rack end stud 30 is a movable portion outside the vehicle width with respect to the rack housing 20 fixed to the vehicle body, it is more reliable that the rack boot 401 is not detached when the elastic body portion 41a is provided on the rack housing 20 side. Increases nature.

Further, in the above-described impact mitigation device, the bellows bent portion 44 (outer diameter side bent portion 44o, inner diameter side bent portion 44i) of the bellows tube 42 at the stroke end position is radially outward with respect to the elastic body portions 41a and 41b. However, as shown in FIG. 5, a rack boot 402 formed on the outer side in the radial direction of the elastic body portions 41 a and 41 b may be used for both the outer diameter side bent portion 44 o and the inner diameter side bent portion 44 i.
In this case, the relationship is as follows.
Ro> ro and Ri> ro

Further, the outer diameter side bent portion 44o and the inner diameter side bent portion 44i of the bellows bent portion 44 may be formed on the radially inner side of the elastic body portions 41a and 41b.
In this case, the relationship is as follows.
Ro <ri and Ri <ri

  Further, in the above-described impact mitigating device, the elastic body portions 41a and 41b are formed in a ring shape and the entire circumference thereof is used as an impact mitigating member, but the impact mitigating elastic body portion is partially disposed. You may do it. For example, as shown in FIG. 6, a rack boot 403 in which elastic bodies 45a, 45b, 45c, 45d, 45e, and 45f for shock relaxation are integrally formed at the end at predetermined intervals in the circumferential direction may be used. . FIG. 6 is a radial cut surface at the end of the rack boot 403.

  The rack stroke end impact mitigating device of this embodiment has been described above. However, the present invention is not limited to the above embodiment, and various modifications can be made without departing from the object of the present invention.

It is sectional drawing (at the time of a non-full stroke) of the impact relaxation apparatus of embodiment. It is sectional drawing (at the time of a full stroke) of the impact relaxation apparatus of embodiment. It is sectional drawing (at the time of a non-full stroke) of the impact mitigation device of a modification. It is sectional drawing (at the time of a full stroke) of the impact relaxation apparatus of a modification. It is sectional drawing (at the time of a non-full stroke) of the impact relaxation apparatus of another modification. It is sectional drawing showing the radial direction cut surface of the rack boot end part of another modification. It is a schematic block diagram of the steering device with which an impact mitigation device is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Steering handle, 2 ... Steering shaft, 3 ... Pinion gear part, 10 ... Rack shaft, 11 ... Rack end socket, 12 ... Ring-shaped plane, 20 ... Rack housing, 21 ... Opening part, 22 ... End cylindrical part, 24 ... Opening recess, 25 ... Ring-shaped step, 26 ... Ring-shaped flat surface, 30 ... Rack end stud, 31 ... Ball joint, 32 ... Hook-shaped part, 40, 401, 402, 403 ... Rack boot, 41a, 41b ... Impact Relaxing elastic body part, 42 ... bellows tube, 44 ... bellows bent part, 44o ... outer diameter side bent part, 44i ... inner diameter side bent part, 401 ... rack boot.

Claims (5)

A rack shaft that is displaced in the axial direction in accordance with a steering operation;
A rack housing fixed to the vehicle body, exposing a tip of the rack shaft, and accommodating the rack shaft movably in an axial direction;
A connecting shaft that is swingably connected to the tip of the rack shaft, and that transmits the operating force of the rack shaft to the wheels;
A rack boot having one end connected to the rack housing and the other end connected to the connecting shaft, and covering the exposed end of the rack shaft and the connecting portion between the rack shaft and the connecting shaft with a bellows tube;
A rack stroke end that is provided in a steering device that includes a stopper that restricts the movement of the rack shaft in the axial direction and sets the stroke end position, and that reduces shock when the rack shaft reaches the stroke end position. In the shock mitigation device,
At least one end portion of the rack boot is integrated with an impact relaxation elastic body portion that is sandwiched between the connecting shaft and the rack housing when the rack shaft reaches the stroke end position, so as to reduce the impact. An impact mitigation device at the rack stroke end, characterized by being formed. The connecting shaft is formed with an opposing wall facing the tip cylindrical portion of the rack housing in the rack axial direction, and
The impact relaxation elastic body portion provided at at least one end portion of the rack boot is provided at an end portion of the front end tubular portion of the rack housing or an opposing wall formed on the coupling shaft, and the rack shaft 2. The rack stroke end according to claim 1, wherein the shock is mitigated by being sandwiched between an opposing wall of the connecting shaft and a tip cylindrical portion of the rack housing when the stroke end position is reached. Shock relief device.   The rack boot is provided with an elastic body for shock relaxation integrally formed at both ends, one elastic body for shock relaxation is provided at the end of the cylindrical portion at the front end of the rack housing, and the other elastic body for shock relaxation. The impact reducing device for a rack stroke end according to claim 2, wherein the body part is provided on an opposing wall formed on the connecting shaft.   The bellows bending portion of the bellows tube of the rack boot is more than the region where the elastic body for shock reduction receives an impact load between the connecting shaft and the rack housing when the rack shaft reaches the stroke end position. The rack stroke end impact mitigating device according to any one of claims 1 to 3, wherein the device is provided at a position deviated from an inner side or an outer side in the radial direction of the rack shaft.   The stopper includes a ring-shaped step provided on the inner side in the vehicle width direction from the end of the end tubular portion of the rack housing, and a ball joint fixed to the end of the rack shaft and movably connecting the connecting shaft. The rack stroke end impact mitigating device according to any one of claims 1 to 4, wherein movement of the rack shaft in the axial direction is restricted by contact with the casing.

Images