JP2009143426A - Rack boot - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rack boot capable of absorbing peripheral direction displacement in relation to a housing of a rod and having durability against a collision with a foreign matter. <P>SOLUTION: This rack boot 1 is provided with a bellows cylindrical part 2 formed of metal, a vehicle width direction outside cylindrical part 3, a vehicle width direction inside cylindrical part 4, a first peripheral direction displacement absorption means for fluid-tightly connecting an inner peripheral surface of the vehicle width direction outside cylindrical part 3 and an outer peripheral surface of a rod 55 constituting a steering device 51 and absorbing the peripheral direction displacement of the vehicle width direction outside cylindrical part 3 and the rod 55, and a second peripheral direction displacement absorbing means for fluid-tightly connecting an inner peripheral surface of the vehicle width direction inside cylindrical part 4 and an outer peripheral surface of the housing 52 constituting the steering device 51 and absorbing the peripheral direction displacement of the vehicle width direction inside cylindrical part 4 and the housing 52. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a rack boot suitable for being applied to a steering apparatus for a vehicle such as a passenger car, a truck, or a bus.

Conventionally, a rack and pinion type steering device is often used as a steering device for steering a vehicle. In this rack and pinion type steering device, the steering force input by the steering wheel is transmitted from the pinion to the rack bar extending in the vehicle width direction, and the outer end of the rack bar in the vehicle width direction is connected via a ball joint. The rod is connected to the outer end in the vehicle width direction of the rod and the tie rod via an adapting tube. The outer end of the tie rod in the vehicle width direction is connected to a knuckle that rotatably supports the wheel. In such a steering apparatus, a bellows cylindrical rack as described in Patent Document 1, for example, is provided to prevent water and dust from entering the rack bar and the ball joint from the outside. A boot is provided, and an inner end in the vehicle width direction of the rack boot is connected to a housing of a steering gear box that encloses the rack bar, and an outer end in the vehicle width direction is connected to a rod.
JP 2002-87314 A

  However, in such a prior art, the tie rod of the steering device is inputted with the swing caused by the bounce and rebound of the wheel and the knuckle, and the rod is rotated around its central axis. Between the inner end portion in the direction and the outer end portion in the vehicle width direction, the rack boot must be made of an elastic member such as rubber in order to absorb the circumferential displacement around the central axis of the rod with respect to the housing of the rod. It was. However, the rack boots must have durability against collisions of foreign objects such as tree branches and stepping stones when the vehicle is running. If the rack boots are made of metal in order to have this durability, the central axis of the rod There arises a problem that surrounding circumferential displacement cannot be absorbed.

  In view of the above problems, an object of the present invention is to provide a rack boot that can absorb the displacement of the rod in the circumferential direction with respect to the housing and can have durability against the collision of foreign matter.

To solve the above problem,
The rack boot according to the present invention is
A bellows cylindrical portion made of metal, a vehicle width direction outer cylindrical portion, a vehicle width direction inner cylindrical portion,
The inner circumferential surface of the outer cylindrical portion in the vehicle width direction and the outer circumferential surface of the rod constituting the steering device are liquid-tightly connected, and the first displacement absorbing the circumferential displacement between the outer cylindrical portion in the vehicle width direction and the rod Circumferential displacement absorbing means;
A second liquid-tightly connecting the inner peripheral surface of the inner cylindrical portion in the vehicle width direction and the outer peripheral surface of the housing constituting the steering device, and absorbing the circumferential displacement between the inner cylindrical portion in the vehicle width direction and the housing. Circumferential displacement absorbing means;
It is characterized by providing.

  The housing refers to a housing of a steering gear box that constitutes the steering device.

  According to this, even if the rod constituting the steering device rotates with respect to the housing due to the bounding and rebounding of the wheel and the knuckle, the central axis of the rod with respect to the housing of the rod Since the first circumferential direction displacement absorbing means and the second circumferential direction displacement means can absorb the circumferential circumferential displacement, the bellows cylindrical portion can be prevented from being twisted in the circumferential direction. .

  Thereby, when the bellows cylindrical portion is made of metal, the inconvenience that the circumferential displacement cannot be absorbed can be solved, and durability against collision of foreign matter can be provided.

Here, in the rack boots,
The first circumferential direction displacement absorbing means is a cylindrical anisotropic elastic member interposed between an inner circumferential surface of the outer cylindrical portion in the vehicle width direction and an outer circumferential surface of the rod, The elastic modulus in the circumferential direction and shear direction of the elastic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
The second circumferential displacement absorbing means is a cylindrical anisotropic elastic member interposed between an inner circumferential surface of the inner cylindrical portion in the vehicle width direction and an outer circumferential surface of the housing, The elastic modulus in the circumferential direction and shear direction of the elastic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
It is characterized by
It is preferable.

  According to this, said 1st and 2nd circumferential direction displacement absorption means can be comprised more simply. In addition, in order to improve the liquid-tightness, that is, the sealing performance between the rod-width outer cylindrical portion of the rack boot and the rod, a fastening member such as a tightening band is used. Even if the anisotropic elastic member is compressed in the radial direction by tightening the outer peripheral surface, the elastic modulus of the anisotropic elastic member in the circumferential direction and shear direction is smaller than the elastic coefficient in the radial direction and compression direction. It is possible to prevent the function of absorbing the circumferential displacement from being impaired.

  Similarly, in order to enhance the liquid tightness, that is, the sealing performance between the vehicle width direction inner cylindrical portion of the rack boot and the housing, a fastening member such as a tightening band is used to Even if the anisotropic elastic member is compressed in the radial direction by tightening the outer peripheral surface, the elastic modulus of the anisotropic elastic member in the circumferential direction and shear direction is smaller than the elastic coefficient in the radial direction and compression direction. It is possible to prevent the function of absorbing the circumferential displacement from being impaired.

  Further, since the anisotropic elastic member has a large elastic coefficient in the radial direction and in the compression direction, a fastening margin for fastening the outer portion in the vehicle width direction and liquid-tightly connecting to the rod by a fastening member such as a fastening band. Can be secured sufficiently. Similarly, by using a fastening member such as a fastening band, it is possible to sufficiently secure a fastening allowance when the inner portion in the vehicle width direction is fastened and liquid-tightly connected to the housing. That is, the function for absorbing the circumferential displacement and the function for improving the liquid tightness, that is, the sealing property can be made compatible.

Alternatively, in the rack boots,
The first circumferential direction displacement absorbing means includes a first cylindrical member interposed between an inner circumferential surface of the vehicle width direction outer cylindrical portion and an outer circumferential surface of the rod; A cylindrical first elastic member interposed between the peripheral surface and the outer peripheral surface of the first cylindrical member, and interposed between the inner peripheral surface of the first cylindrical member and the outer peripheral surface of the rod. A cylindrical second elastic member, and
The second circumferential direction displacement absorbing means includes a second cylindrical member interposed between an inner circumferential surface of the vehicle width direction inner cylindrical portion and an outer circumferential surface of the housing; A cylindrical third elastic member interposed between the peripheral surface and the outer peripheral surface of the second cylindrical member, and interposed between the inner peripheral surface of the second cylindrical member and the outer peripheral surface of the housing. A cylindrical fourth elastic member, and
The first elastic member is offset to the inner side in the vehicle width direction of the second elastic member, and the third elastic member is offset to the outer side in the vehicle width direction of the fourth elastic member,
This may be a feature.

  This also makes it possible to more simply configure the first and second circumferential displacement absorbing means. In addition, an outer peripheral surface of the first cylindrical member is used by using a fastening member such as a fastening band in order to improve the liquid tightness, that is, the sealing performance between the outer cylindrical portion in the vehicle width direction of the rack boot and the rod. Even if the second elastic member is compressed in the radial direction by tightening the screw, the first elastic member is not compressed in the radial direction. It is possible to prevent the function of absorbing the circumferential displacement from being impaired.

  Similarly, an outer peripheral surface of the second cylindrical member is used by using a fastening member such as a fastening band in order to improve the liquid tightness, that is, the sealing performance between the inner cylindrical portion of the rack boot in the vehicle width direction and the housing. Even if the fourth elastic member is compressed in the radial direction by tightening the second elastic member, the third elastic member is not compressed in the radial direction. It is possible to prevent the function of absorbing the circumferential displacement from being impaired.

  Furthermore, since the first elastic member is subjected to circumferential displacement, the second elastic member can increase the elastic coefficient in the radial direction and the compression direction. It is possible to secure a sufficient tightening margin when the cylindrical member is tightened and liquid-tightly connected to the rod.

  Similarly, since the third elastic member is subjected to circumferential displacement, the fourth elastic member can increase the elastic coefficient in the radial direction and in the compression direction. It is possible to secure a sufficient tightening margin when the two cylindrical members are tightened and liquid-tightly connected to the housing. That is, the function for absorbing the circumferential displacement and the function for improving the liquid tightness, that is, the sealing property can be made compatible.

Even in this case,
The first elastic member and the third elastic member are anisotropic elastic members, and the elastic modulus in the circumferential direction and shear direction of the anisotropic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
It is preferable to be characterized by this.

  According to this, the function which absorbs the said circumferential direction displacement can be improved more.

  ADVANTAGE OF THE INVENTION According to this invention, the rack boot which can absorb the circumferential direction displacement with respect to the housing of a rod, and can have the durability with respect to the collision of a foreign material can be provided.

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

  FIG. 1 is a schematic diagram showing a steering apparatus to which an embodiment of a rack boot according to the present invention is applied. FIG. 2 is a schematic cross-sectional view showing an embodiment of a rack boot according to the present invention.

  As shown in FIGS. 1 and 2, a steering device 51 to which the rack boot 1 according to the first embodiment is applied includes a housing 52 and a rack bar 53 that is positioned inside the housing 52 and meshed with a pinion (not shown). And a rod 55 connected to the outer end of the rack bar 53 in the vehicle width direction via a ball joint 54, and a tie rod 57 connected to the outer end of the rod 55 in the vehicle width direction via an adjusting tube 56. Is done. The outer end of the tie rod 57 in the vehicle width direction is connected to a knuckle that rotatably supports a wheel (not shown).

  Steering force input by a steering wheel (not shown) is transmitted from the pinion to a rack bar 53 extending in the vehicle width direction, and the movement of the rack bar 53 in the vehicle width direction is performed via the ball joint 54 and the rod 55 and The wheel and knuckle are steered by being transmitted to the tie rod 57.

  In such a steering device 51, a bellows cylindrical rack boot 1 is provided in order to prevent water and dust from entering the sliding portion including the rack bar 53 and the ball joint 54 from the outside. Yes.

  The rack boot 1 includes a bellows cylindrical portion 2 made of metal, an outer cylindrical portion 3 in the vehicle width direction, an inner cylindrical portion 4 in the vehicle width direction, an inner peripheral surface of the outer cylindrical portion 3 in the vehicle width direction, and a steering device. A first circumferential displacement absorbing means for fluidly connecting the outer peripheral surface of the rod 55 constituting the shaft 51 and absorbing a circumferential displacement between the outer cylindrical portion 3 in the vehicle width direction and the rod 55; and an inner cylinder in the vehicle width direction. A second circumferential displacement that couples the inner circumferential surface of the portion 4 and the outer circumferential surface of the housing 52 constituting the steering device 51 in a liquid-tight manner and absorbs the circumferential displacement between the inner cylindrical portion 4 in the vehicle width direction and the housing 52. Absorption means. The bellows cylindrical portion 2, the vehicle width direction outer cylindrical portion 3, and the vehicle width direction inner cylindrical portion 4 are integrally formed of metal.

  The bellows cylindrical portion 2 of the rack boot 1 is configured in a bellows shape, so that the displacement of the rod 55 when it swings up and down and back and forth around the ball joint 54 is absorbed.

  The first circumferential displacement absorbing means is a cylindrical anisotropic elastic member 5 interposed between the inner peripheral surface of the outer cylindrical portion 3 in the vehicle width direction and the outer peripheral surface of the rod 55. The elastic coefficient Kθ in the circumferential direction and shear direction of the isotropic elastic member 5 is configured to be smaller than the elastic coefficient Kr in the radial direction and compression direction. The outer peripheral surface of the cylindrical anisotropic elastic member 5 is joined in advance to the inner peripheral surface of the outer cylindrical portion 3 in the vehicle width direction by vulcanization adhesion or an adhesive.

  Further, the second circumferential direction displacement absorbing means is a cylindrical anisotropic elastic member 6 interposed between the inner peripheral surface of the inner cylindrical portion 4 in the vehicle width direction and the outer peripheral surface of the housing 52. The elastic coefficient Kθ in the circumferential direction and shear direction of the isotropic elastic member 6 is configured to be smaller than the elastic coefficient Kr in the radial direction and compression direction. The outer peripheral surface of the cylindrical anisotropic elastic member 6 is joined in advance to the inner peripheral surface of the inner cylindrical portion 4 in the vehicle width direction by vulcanization adhesion or an adhesive.

  A plurality of cutouts 3 a are provided in the circumferential direction in the vehicle width direction outer cylindrical portion 3, and a fastening band 7 is provided on the outer peripheral surface of the vehicle width direction outer cylindrical portion 3. Further, the vehicle width direction inner cylindrical portion 4 is provided with a plurality of notches 4 a at equal intervals in the circumferential direction, and a fastening band 8 is provided on the outer peripheral surface of the vehicle width direction inner cylindrical portion 4.

  In assembling the steering device 51, first, the outer cylindrical portion 3 in the vehicle width direction of the rack boot 1 is inserted to a predetermined position on the outer peripheral surface of the rod 55 based on the deformation in the radial direction by the notch 3a. Thereafter, the rod 55 is connected to a stud constituting the ball joint 54 by a screw portion (not shown), and then the inner side portion 4 of the rack boot 1 in the vehicle width direction is deformed outwardly in the radial direction by the notch 4a. 52 is inserted to a predetermined position on the outer peripheral surface. The vehicle width direction outer side cylindrical portion 3 is reduced in diameter by the elastic force action of the anisotropic elastic member 5 after being inserted into the rod 55, and similarly, the vehicle width direction inner side portion 4 is inserted into the housing 52. Is reduced in diameter by the elastic force action of the anisotropic elastic member 6.

  Thereafter, the outer peripheral surface of the outer cylindrical portion 3 in the vehicle width direction of the rack boot 1 is tightened by the tightening band 7, the anisotropic elastic member 5 is compressed in the radial direction, and the inner portion of the rack boot 1 in the vehicle width direction is tightened by the tightening band 8. 4 is tightened and the anisotropic elastic member 6 is compressed in the radial direction.

  As a result, the outer cylindrical portion 3 in the vehicle width direction of the rack boot 1 is liquid-tightly connected to the rod 55, and the inner cylindrical portion 4 in the vehicle width direction is liquid-tight to the housing 52 of the steering gear box that encloses the rack bar 53. Connected.

  According to the rack boot 1 of the first embodiment described above, the following operational effects can be obtained. That is, even if the rod 55 constituting the steering device 51 rotates with respect to the housing 52 due to bounce and rebound of wheels and knuckles (not shown), the rod 55 rotates about the central axis of the rod 55 relative to the housing 52. Since the first circumferential displacement absorbing means and the second circumferential displacement means can absorb the circumferential displacement, the metal bellows cylindrical portion 2 of the rack boot 1 is prevented from being twisted in the circumferential direction. can do.

  Thereby, even when the bellows cylindrical portion 2 is made of metal, it is possible to eliminate the inconvenience that the displacement of the rod 55 around the central axis of the rod 55 relative to the housing 52 cannot be absorbed. In addition, by making the bellows cylindrical portion 2 of the rack boot 1 made of metal, sufficient durability can be provided against collision of foreign matters such as tree branches and stepping stones.

  Further, the first circumferential displacement absorbing means is constituted by a cylindrical anisotropic elastic member 5 interposed between the inner circumferential surface of the outer cylindrical portion 3 in the vehicle width direction and the outer circumferential surface of the rod 55. The elastic coefficient Kθ in the circumferential direction and shear direction of the isotropic elastic member 5 is made smaller than the elastic coefficient Kr in the radial direction and compression direction, and the second circumferential displacement absorbing means is used as the inner circumference of the inner cylindrical portion 4 in the vehicle width direction. As the cylindrical anisotropic elastic member 6 interposed between the surface and the outer peripheral surface of the housing 52, the elastic modulus Kθ in the circumferential direction and shear direction of the anisotropic elastic member 6 is set in the radial direction and the compression direction. By making it smaller than the elastic coefficient Kr, the following effects can be obtained.

  That is, the first and second circumferential displacement absorbing means can be configured more simply. In addition, in order to improve the liquid tightness between the outer cylindrical portion 3 in the vehicle width direction of the rack boot 1 and the rod 55, that is, the outer peripheral surface of the outer cylindrical portion 3 in the vehicle width direction is used by using the fastening band 7. Even if the anisotropic elastic member 5 is compressed in the radial direction by tightening, the elastic modulus Kθ in the circumferential direction and the shearing direction of the anisotropic elastic member 5 is smaller than the elastic coefficient Kr in the radial direction and the compression direction. Since the outer circumferential surface of the anisotropic elastic member 5 can be greatly deformed in the circumferential direction with respect to the inner circumferential surface, the displacement in the circumferential direction around the central axis of the rod 55 relative to the housing 52 of the rod 55 can be sufficiently absorbed.

  Similarly, in order to improve the liquid tightness, that is, the sealing performance between the vehicle width direction inner cylindrical portion 4 of the rack boot 1 and the housing 52, the outer peripheral surface of the vehicle width direction inner cylindrical portion 4 is used by using the fastening band 8. Even if the anisotropic elastic member 6 is compressed in the radial direction by tightening, the anisotropic elastic member 6 has an elastic coefficient Kθ in the circumferential direction and shear direction smaller than the elastic coefficient Kr in the radial direction and compression direction. The circumferential displacement of the rod 55 around the central axis of the rod 55 relative to the housing 52 can be sufficiently absorbed. By these things, it can prevent impairing the function which absorbs circumferential direction displacement.

  In addition, since the anisotropic elastic member 5 has a large elastic coefficient Kr in the radial direction and in the compression direction, the tightening band 7 is used to tighten the outer portion 3 in the vehicle width direction and connect the rod 55 in a liquid-tight manner. It can be secured sufficiently. Similarly, since the anisotropic elastic member 6 has a large elastic coefficient Kr in the radial direction and in the compression direction, the tightening allowance for tightening the inner portion 4 in the vehicle width direction and liquid-tightly connecting the housing 52 with the tightening band 8 is also possible. It can be secured sufficiently. That is, in the rack boot 1, a function for absorbing the circumferential displacement and a function for improving the liquid tightness, that is, the sealing property can be achieved.

  According to the rack boot 1 of the first embodiment described above, the first and second circumferential displacement absorbing means are configured using the anisotropic elastic members 5 and 6, but the following configuration is adopted. You can also. A second embodiment of the configuration will be described below.

  Since the structure of the steering device 51 which is a premise is the same as that shown in the first embodiment, the same reference numerals are given to the presupposing components, and individual descriptions are omitted. Only the differences will be described below with reference to the drawings. FIG. 3 is a schematic cross-sectional view showing another embodiment of the rack boot according to the present invention.

  As shown in FIG. 3, in the rack boot 21 of the second embodiment, the first circumferential displacement absorbing means is interposed between the inner circumferential surface of the outer cylindrical portion 3 in the vehicle width direction and the outer circumferential surface of the rod 55. The first cylindrical member 9, the cylindrical first elastic member 10 interposed between the inner peripheral surface of the outer cylindrical portion 3 in the vehicle width direction and the outer peripheral surface of the first cylindrical member 9, and the first cylinder A cylindrical second elastic member 11 interposed between the inner peripheral surface of the member 9 and the outer peripheral surface of the rod 55 is provided.

  The outer peripheral surface of the cylindrical first elastic member 10 is joined in advance to the inner peripheral surface of the outer cylindrical portion 3 in the vehicle width direction by vulcanization adhesion or an adhesive, and the inner peripheral surface of the first elastic member 10 is the first cylinder. The member 9 is preliminarily bonded to the outer peripheral surface of the member 9 by vulcanization bonding or an adhesive. Furthermore, the outer peripheral surface of the second elastic member 11 is joined in advance to the inner peripheral surface of the first cylindrical member 9 by vulcanization adhesion or an adhesive.

  Similarly, the second circumferential direction displacement absorbing means includes a second cylindrical member 12 interposed between the inner peripheral surface of the vehicle width direction inner cylindrical portion 4 and the outer peripheral surface of the housing 52, and the vehicle width direction inner cylindrical portion. 4 between the inner peripheral surface of 4 and the outer peripheral surface of the second cylindrical member 12, and between the inner peripheral surface of the second cylindrical member 12 and the outer peripheral surface of the housing 52. And a cylindrical fourth elastic member 14 interposed therebetween.

  The outer peripheral surface of the cylindrical third elastic member 13 is joined in advance to the inner peripheral surface of the inner cylindrical portion 4 in the vehicle width direction by vulcanization adhesion or an adhesive, and the inner peripheral surface of the third elastic member 13 is the second cylinder. The member 12 is previously joined to the outer peripheral surface of the member 12 by vulcanization adhesion or adhesive. Furthermore, the outer peripheral surface of the fourth elastic member 14 is joined in advance to the inner peripheral surface of the second cylindrical member 12 by vulcanization adhesion or adhesive.

  In addition, the first elastic member 10 is offset inside the second elastic member 11 in the vehicle width direction. Accordingly, the axial length of the first cylindrical member 9 is the sum of the axial length of the first elastic member 10 and the axial length of the second elastic member 11, and the first cylindrical member 9 is a rack boot 21. The second elastic member 12 is positioned so as to protrude outward in the vehicle width direction from the outer end in the vehicle width direction of the outer cylindrical portion 3 in the vehicle width direction.

  Similarly, the third elastic member 13 is offset to the outer side in the vehicle width direction of the fourth elastic member 14. Accordingly, the axial length of the second cylindrical member 12 is a length obtained by adding the axial length of the third elastic member 13 and the axial length of the fourth elastic member 14, and the second cylindrical member 12 has the rack boot 21. The fourth elastic member 14 is positioned so as to protrude inward in the vehicle width direction from the inner end in the vehicle width direction of the inner cylindrical portion 4 in the vehicle width direction.

  Also by this, the 1st and 2nd circumferential direction displacement absorption means can be comprised more simply. In addition, the outer peripheral surface of the first cylindrical member 9 is tightened using the tightening band 7 in order to improve the liquid tightness, that is, the sealing performance between the outer cylindrical portion 3 in the vehicle width direction of the rack boot 21 and the rod 55. Even if the second elastic member 11 is compressed in the radial direction, the first elastic member 10 is not compressed in the radial direction, so that the first elastic member 10 has a function of absorbing the circumferential displacement, and the rod 55 A circumferential displacement around the central axis of the rod 55 relative to the housing 52 can be sufficiently absorbed.

  Similarly, the outer peripheral surface of the second cylindrical member 12 is tightened by using the tightening band 8 in order to improve the liquid tightness, that is, the sealing performance between the inner cylindrical portion 4 of the rack boot 21 in the vehicle width direction and the housing 52. Even if the fourth elastic member 14 is compressed in the radial direction, the third elastic member 13 is not compressed in the radial direction, so that the third elastic member 13 has a function of absorbing the circumferential displacement, and the rod 55 A circumferential displacement around the central axis of the rod 55 relative to the housing 52 can be sufficiently absorbed. By these things, it can prevent impairing the function which absorbs circumferential direction displacement.

  Further, since the first elastic member 10 is subjected to the circumferential displacement, the second elastic member 11 can increase the elastic coefficient Kr in the radial direction and the compression direction. It is possible to secure a sufficient margin for tightening and connecting the rod 55 in a liquid-tight manner.

  Similarly, since the third elastic member 13 is subjected to circumferential displacement, the fourth elastic member 14 can increase the elastic coefficient Kr in the radial direction and in the compression direction. It is possible to secure a sufficient margin for tightening 12 and liquid-tightly connecting to the housing 52. That is, also in the rack boot 21, the function for absorbing the circumferential displacement and the function for improving the liquid tightness, that is, the sealing property can be achieved.

  In addition, the following effects can be obtained by the rack boot 21 of the second embodiment. That is, even if the rod 55 constituting the steering device 51 rotates with respect to the housing 52 due to bounce and rebound of wheels and knuckles (not shown), the rod 55 rotates about the central axis of the rod 55 relative to the housing 52. Since the first circumferential direction displacement absorbing means and the second circumferential direction displacement means can absorb the circumferential displacement, the metal bellows cylindrical portion 2 of the rack boot 21 is prevented from being twisted in the circumferential direction. can do.

  Thereby, even when the bellows cylindrical portion 2 is made of metal, it is possible to eliminate the inconvenience that the displacement of the rod 55 around the central axis of the rod 55 relative to the housing 52 cannot be absorbed. In addition, by making the bellows cylindrical portion 2 of the rack boot 21 made of metal, sufficient durability can be provided against collisions of foreign matters such as tree branches and stepping stones.

  Also in the rack boot 21 shown in the second embodiment, the first elastic member 10 and the third elastic member 13 are anisotropic elastic members, and the elastic modulus in the circumferential direction and shear direction of the anisotropic elastic member. It is preferable that Kθ be smaller than the elastic coefficient Kr in the radial direction and the compression direction. According to this, the function which absorbs circumferential direction displacement can be improved more.

  Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications and substitutions are made to the above-described embodiments without departing from the scope of the present invention. be able to.

  The present invention relates to a rack boot suitable for application to a steering apparatus for a vehicle, and can absorb circumferential displacement of a rod with respect to a housing and can have durability against foreign object collisions. It is also useful when applied to various vehicles such as buses.

It is a mimetic diagram showing a steering device used as an application object of one embodiment of a rack boot concerning the present invention. 1 is a schematic cross-sectional view showing an embodiment of a rack boot according to the present invention. 1 is a schematic cross-sectional view showing an embodiment of a rack boot according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Rack boot 2 Bellows cylindrical part 3 Car width direction outer side cylindrical part 3a Notch 4 Car width direction inner side cylindrical part 4a Notch 5 Anisotropic elastic member 6 Anisotropic elastic member 7 Tightening band 8 Tightening band 9 First cylinder Member 10 First elastic member 11 Second elastic member 12 Second cylindrical member 13 Third elastic member 14 Fourth elastic member 21 Rack boot 51 Steering device 52 Housing 53 Rack bar 54 Ball joint 55 Rod 56 Adjusting tube 57 Tie rod

Claims (4)

A bellows cylindrical portion made of metal, a vehicle width direction outer cylindrical portion, a vehicle width direction inner cylindrical portion,
The inner circumferential surface of the outer cylindrical portion in the vehicle width direction and the outer circumferential surface of the rod constituting the steering device are liquid-tightly connected, and the first displacement absorbing the circumferential displacement between the outer cylindrical portion in the vehicle width direction and the rod Circumferential displacement absorbing means;
A second liquid-tightly connecting the inner peripheral surface of the inner cylindrical portion in the vehicle width direction and the outer peripheral surface of the housing constituting the steering device, and absorbing the circumferential displacement between the inner cylindrical portion in the vehicle width direction and the housing. Circumferential displacement absorbing means;
A rack boot characterized by comprising: The first circumferential direction displacement absorbing means is a cylindrical anisotropic elastic member interposed between an inner circumferential surface of the outer cylindrical portion in the vehicle width direction and an outer circumferential surface of the rod, The elastic modulus in the circumferential direction and shear direction of the elastic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
The second circumferential displacement absorbing means is a cylindrical anisotropic elastic member interposed between an inner circumferential surface of the inner cylindrical portion in the vehicle width direction and an outer circumferential surface of the housing, The elastic modulus in the circumferential direction and shear direction of the elastic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
The rack boot according to claim 1. The first circumferential direction displacement absorbing means includes a first cylindrical member interposed between an inner circumferential surface of the vehicle width direction outer cylindrical portion and an outer circumferential surface of the rod; and an inner portion of the vehicle width direction outer cylindrical portion. A cylindrical first elastic member interposed between the peripheral surface and the outer peripheral surface of the first cylindrical member, and interposed between the inner peripheral surface of the first cylindrical member and the outer peripheral surface of the rod. A cylindrical second elastic member, and
A second cylindrical member interposed between an inner peripheral surface of the inner cylinder portion in the vehicle width direction and an outer peripheral surface of the housing; and an inner portion of the inner cylindrical portion in the vehicle width direction. A cylindrical third elastic member interposed between the peripheral surface and the outer peripheral surface of the second cylindrical member, and interposed between the inner peripheral surface of the second cylindrical member and the outer peripheral surface of the housing. A cylindrical fourth elastic member, and
The first elastic member is offset to the inner side in the vehicle width direction of the second elastic member, and the third elastic member is offset to the outer side in the vehicle width direction of the fourth elastic member,
The rack boot according to claim 1. The first elastic member and the third elastic member are anisotropic elastic members, and the elastic modulus in the circumferential direction and shear direction of the anisotropic elastic member is smaller than the elastic coefficient in the radial direction and compression direction,
The rack boot according to claim 3.

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