JP2020094648A - Boot attachment structure - Google Patents

Abstract

To provide a boot attachment structure which can improve seal performance.SOLUTION: An opening end part 26 of a cylindrical part 21 of a rack housing 13 comprises an annular fixing part 41 including a shaft end face 21a at one side in an axial direction, and a main body part 42 arranged at the other end side of the fixing part 41 in the axial direction, and protruding to the outside in a radial direction over an entire area in a peripheral direction rather than an external peripheral face of the fixing part 41. A boot 27 comprises: a boot main body 51 having a cylindrical flexible part 52 which can be deformed to the axial direction of the cylindrical part 21, and to a direction intersecting with the axial direction, an annular small-diameter end part 53 arranged at one end side of the flexible part 52 in the axial direction, and an annular connecting end part 54 arranged at the other end side of the flexible part 52 in the axial direction; and an annular ring member 55 composed of a metal material, and arranged at an internal periphery of the connecting end part 54. An annular seal part 65 which is compressed in the axial direction between the main body part 42 and the ring member 55 is formed at the connecting end part 54.SELECTED DRAWING: Figure 2

Description

The present invention relates to a boot mounting structure.

2. Description of the Related Art Conventionally, there is a steering device for a vehicle that changes a steering angle of a steered wheel by converting a rotation of a steering shaft accompanying steering of a steering wheel into a reciprocating motion of a rack shaft by a rack and pinion mechanism. In such a steering device, the rack shaft is reciprocally housed in a substantially cylindrical rack housing, and the steered wheels are connected to both ends of the rack shaft via ball joints and tie rods.

Here, in order to prevent foreign matter such as dust and rainwater from entering the rack housing, both ends of the boot formed in a tubular shape are fixed to the open end of the rack housing and the ball shaft of the ball joint, respectively. There is something to do. For example, in the steering device described in Patent Document 1, the large diameter tubular portion of the boot is fitted to the outer periphery of the opening end portion of the rack housing, and the small diameter tubular portion of the boot is fitted to the outer periphery of the ball shaft. The boots are fixed by attaching a boot band.

As such a boot band, for example, a band-shaped band member which is curved in an annular shape and whose both ends are joined, and a lever which is fixed to a joint portion of the band member are provided, and the band member is contracted by tilting the lever. There is one in which the boot is fastened with a diameter (for example, Patent Document 2).

JP, 2008-43658, A JP, 2009-197866, A

However, in the boot band as disclosed in Patent Document 2, since a part of the band member does not come into contact with the boot (large-diameter cylindrical portion), it is difficult to uniformly tighten the boot over the entire circumference. The sealability may be reduced. Therefore, there has been a demand for the development of a new boot attachment structure capable of improving the sealing property.

It should be noted that such a problem may occur not only when the rack housing is used as the boot attachment target, but also when the outer race of the constant velocity joint or the like is attached.
An object of the present invention is to provide a boot mounting structure that can improve the sealing performance.

A boot mounting structure that solves the above problem is one in which a boot is mounted on an opening end of a tubular portion of an object to be mounted, and the opening end includes an axial end surface on one axial end side of the tubular portion. An annular fixing portion and an annular wall portion that is provided on the other end side in the axial direction of the fixing portion and that protrudes radially outward from the outer peripheral surface of the fixing portion are provided, and the boot is made of an elastic material, A boot having a tubular flexible portion that is deformable in the axial direction of the tubular portion and a direction intersecting the axial direction, and an annular connecting end portion provided on the other end side in the axial direction of the flexible portion. A main body; and an annular ring member made of a metal material, which is provided on the inner circumference of the connecting end portion and fixed to the outer circumference of the fixing portion, and the connecting end portion has the wall portion and the ring member. An annular seal portion was formed between and to be axially compressed.

According to the above configuration, the seal portion made of the elastic material is axially compressed between the wall portion and the ring member, so that the opening end portion to be attached and the boot are sealed. Since the wall portion and the ring member are each formed in an annular shape, the seal portion can be uniformly compressed over the entire circumference, and the sealing performance can be improved.

In the boot mounting structure, it is preferable that a male screw is formed on the outer periphery of the fixing portion, and a female screw that is screwed into the male screw is formed on the inner periphery of the ring member.
According to the above configuration, the boot can be easily attached to the attachment target by screwing the ring member to the fixing portion.

In the boot mounting structure, it is preferable that the ring member is formed with an abutting portion that abuts the shaft end surface.
According to the above configuration, the ring member is further screwed in the state where the contact portion is in contact with the shaft end surface, so that an axial stress is generated between the ring member (female screw) and the fixing portion (male screw). The boot can be firmly attached to the attachment target.

In the boot attachment structure, it is preferable that the ring member is formed with a grip portion that protrudes outward in the radial direction so as to be exposed from the outer peripheral surface of the coupling end portion.
According to the above configuration, the ring member can be directly gripped by a jig or the like, and the boot can be easily attached to the attachment target.

In the above boot attachment structure, it is preferable that the ring member has a surface subjected to rust prevention treatment.
According to the above configuration, it is possible to prevent the ring member from being rusted, and thus to prevent the foreign matter from passing between the fixed portion and the ring member and entering the rack housing.

In the boot attachment structure, it is preferable that a storage portion is formed in the seal portion, the storage portion being opened in a surface of the seal portion facing the wall portion and filled with a seal material.
According to the above configuration, when the boot is attached to the attachment target and the seal portion flows out from the storage portion when the seal portion is compressed in the axial direction, the space between the wall portion and the seal portion is sealed by the seal material. Thereby, the sealing property can be further improved. Further, the seal material flows out from the storage portion when the seal portion is compressed and seals between the wall portion and the seal portion.For example, after applying the seal material to the seal portion and the wall portion, the boot is attached. Comparing with the case where the boot is attached to the target, the work of attaching the boot can be suppressed from being complicated.

According to the present invention, it is possible to improve the sealing property.

The schematic block diagram of the steering device of a 1st embodiment. (A) is a partial cross-sectional view along the axial direction showing the boot mounting structure in the first embodiment, and (b) is an enlarged cross-sectional view along the axial direction of the connecting end of the boot. The expanded side view of the boot in 1st Embodiment. Sectional drawing orthogonal to the axial direction of the boot in 1st Embodiment (IV-IV sectional view taken on the line of FIG. 3). The expanded sectional view along the axial direction of the connection end part of the boot in a 2nd embodiment. The expanded sectional view along the axial direction of the connection end part of the boot before attachment in a 2nd embodiment.

(First embodiment)
Hereinafter, a first embodiment of a boot attachment structure will be described with reference to the drawings.
As shown in FIG. 1, the steering system 1 applies a steering mechanism 4 that steers the steered wheels 3 based on an operation of a steering wheel 2 by a driver, and an assist force for assisting the steering operation to the steering mechanism 4. And an assist mechanism 5 for performing the operation.

The steering mechanism 4 includes a steering shaft 11 to which the steering wheel 2 is fixed, a rack shaft 12 connected to the steering shaft 11, a rack housing 13 as an attachment object into which the rack shaft 12 is reciprocally inserted, and a steering wheel. The rack and pinion mechanism 14 that converts the rotation of the shaft 11 into the reciprocating motion of the rack shaft 12 is provided. The steering shaft 11 is configured by connecting a column shaft 15, an intermediate shaft 16, and a pinion shaft 17 in order from the side where the steering wheel 2 is located.

The rack shaft 12 is housed in a tubular portion 21 of the rack housing 13 extending in the axial direction so as to be movable in the axial direction. The pinion shaft 17 is arranged in the rack housing 13 at a predetermined intersection angle with the rack shaft 12. The rack and pinion mechanism 14 is configured by meshing the rack teeth 12a formed on the rack shaft 12 with the pinion teeth 17a formed on the pinion shaft 17. Ball joints 22 are provided at both ends of the rack shaft 12, respectively. Each ball joint 22 includes a socket 23 fixed to both ends of the rack shaft 12, and a ball shaft 24 rotatably connected to the socket 23. The ball shaft 24 is connected to a tie rod 25, and the tip of the tie rod 25 is connected to a knuckle (not shown) to which the steered wheels 3 are attached. Therefore, in the steering device 1, the rotation of the steering shaft 11 associated with the steering operation is converted into the axial movement of the rack shaft 12 by the rack and pinion mechanism 14, and this axial movement is transmitted to the knuckle through the tie rod 25. Thus, the steered angle of the steered wheels 3, that is, the traveling direction of the vehicle is changed.

Further, tubular boots 27 are attached to both open end portions 26 of the tubular portion 21 of the rack housing 13 in order to prevent foreign matter such as dust and rainwater from entering the rack housing 13. ..

The assist mechanism 5 includes a motor 31, which is a drive source, a transmission mechanism 32 that transmits the rotation of the motor 31, and a conversion mechanism 33 that converts the rotation transmitted via the transmission mechanism 32 into the reciprocating motion of the rack shaft 12. I have it. Then, the assist mechanism 5 transmits the rotation of the motor 31 to the conversion mechanism 33 via the transmission mechanism 32, and the conversion mechanism 33 converts the rotation of the rack shaft 12 into reciprocating motion, thereby applying an assist force to the steering mechanism 4. .. For example, a three-phase brushless motor is adopted as the motor 31 of the present embodiment, a belt mechanism is adopted as the transmission mechanism 32, and a ball screw mechanism is adopted as the conversion mechanism 33. The assist mechanism 5 may be, for example, of a type that applies an assist force to the steering shaft 11, or the steering device 1 may not include the assist mechanism 5.

Next, the mounting structure of the boot 27 will be described in detail. Since the boots 27 attached to the left and right ends of the rack housing 13 are symmetrical in structure, only the right side attachment structure will be described, and the left side attachment structure will not be described. Further, for convenience of description, the right side in FIG. 2 is one side in the axial direction and the left side is the other side in the axial direction.

As shown in FIGS. 2A and 2B, the rack housing 13 is made of a metal material such as an aluminum alloy. The open end portion 26 of the rack housing 13 (cylindrical portion 21) is formed in a stepped cylindrical shape. The open end portion 26 is an annular fixing portion 41 that includes the axial end surface 21 a on one axial side of the tubular portion 21, and a cylindrical main body portion that is continuously formed on the other axial side of the fixing portion 41. And 42. The shaft end surface 21a is formed as a flat surface orthogonal to the axial direction. A male screw 43 is formed on the outer peripheral surface of the fixed portion 41. The fixed portion 41 and the main body portion 42 are formed coaxially, and the outer diameter of the main body portion 42 is formed larger than the outer diameter of the fixed portion 41 (male screw 43). That is, the main body portion 42 is configured as an annular wall portion that projects radially outward over the entire outer circumferential surface of the fixed portion 41 in the circumferential direction. The step surface 44 between the fixed portion 41 and the main body portion 42 is formed as a flat surface orthogonal to the axial direction.

The boot 27 includes a boot body 51 made of an elastic material such as rubber or resin. The boot body 51 is provided with a tubular flexible portion 52, an annular small-diameter end portion 53 provided at one end side in the axial direction of the flexible portion 52, and the other end side in the axial direction of the flexible portion 52. And an annular connecting end portion 54. Further, the boot 27 of the present embodiment includes a metal ring member 55 integrally provided on the inner circumference of the connecting end portion 54. The ring member 55 of this embodiment is integrally formed with the boot body 51 by insert molding, vulcanization adhesion, or the like.

Specifically, the flexible portion 52 surrounds the ball joint 22. The flexible portion 52 is formed in a bellows shape, for example, and is deformable in the axial direction of the tubular portion 21 and in a direction intersecting the axial direction. The small diameter end portion 53 is formed in an annular shape having an inner diameter substantially equal to the outer diameter of the shaft portion of the ball shaft 24, and is fitted to the outer circumference of the ball shaft 24. A well-known boot band 56 is attached to the outer periphery of the small-diameter end portion 53. As a result, the small-diameter end portion 53 is in close contact with the shaft portion of the ball shaft 24, and seals between them so that foreign matter such as dust and rainwater does not enter.

The ring member 55 is formed in an annular shape. The entire surface of the ring member 55 of this embodiment is subjected to rustproofing treatment such as alumite or zinc plating. The other axial end surface 55a of the ring member 55, which faces the main body portion 42 (stepped surface 44), is formed as a flat surface orthogonal to the axial direction. A female screw 61 that is screwed into the male screw 43 is formed on the inner peripheral surface of the ring member 55. An annular contact portion 62 extending inward in the radial direction is formed at one end of the ring member 55 in the axial direction. A surface of the contact portion 62 facing the shaft end surface 21a is formed as a flat surface orthogonal to the axial direction, and the contact portion 62 is in surface contact with the shaft end surface 21a.

Further, as shown in FIGS. 3 and 4, a plurality of (two in the present embodiment) radially outwardly protruding from the outer peripheral surface of the ring member 55 so as to be exposed from the outer peripheral surface of the connecting end portion 54. A grip portion 63 is formed. The grip portions 63 are formed at positions that are opposed to each other in the radial direction with the center of the ring member 55 interposed therebetween, and the radially outer surfaces of the grip portions 63 are formed in a planar shape that is parallel to each other. That is, the ring member 55 of the present embodiment is provided with a so-called double-width grip portion 63. Thereby, the ring member 55 can be directly gripped by the jig 64, for example.

As shown in FIGS. 2A and 2B, the connecting end portion 54 is formed in an annular shape, and a position corresponding to the grip portion 63 is cut out. An annular seal portion 65 extending inward in the radial direction is integrally formed on the other end side in the axial direction of the connecting end portion 54. The inner diameter of the seal portion 65 is set to be substantially equal to the outer diameter of the main body portion 42. Further, the length (thickness) of the seal portion 65 along the axial direction is determined by the step surface 44 of the opening end portion 26 and the other axial end surface of the ring member 55 when the contact portion 62 is in contact with the shaft end surface 21a. It is set to be larger than the gap along the axial direction between 55a. The connecting end portion 54 is axially compressed between the main body portion 42 and the ring member 55 in a state of being in contact with the step surface 44 of the opening end portion 26 and the axial other end surface 55 a of the ring member 55. ..

Next, attachment of the boot 27 to the rack housing 13 will be described.
When mounting the boot 27, the grip 63 is gripped by, for example, a jig 64, and the female screw 61 of the ring member 55 is screwed onto the male screw 43 of the fixed portion 41. Then, by further screwing the abutting portion 62 into surface contact with the shaft end surface 21a with a predetermined torque, the seal portion 65 is inserted between the main body portion 42 of the opening end portion 26 and the ring member 55. The boot 27 is attached to the rack housing 13 while being compressed in the direction.

Next, the operation and effect of this embodiment will be described.
(1) By compressing the seal portion 65 of the connecting end portion 54 made of an elastic material in the axial direction between the main body portion 42 of the opening end portion 26 and the ring member 55, the opening end portion 26 of the rack housing 13 and The space between the boots 27 is sealed. As described above, since the main body 42 and the ring member 55 are each formed in an annular shape, it is possible to uniformly compress the seal portion 65 over the entire circumference and to improve the sealing performance. You can

(2) Since the male screw 43 is formed on the outer periphery of the fixed portion 41 and the female screw 61 that is screwed into the male screw 43 is formed on the inner periphery of the ring member 55, the ring member 55 is screwed onto the fixed portion 41. The boot 27 can be easily attached to the rack housing 13.

(3) Since the contact member 62 that contacts the shaft end surface 21a of the fixed portion 41 (rack housing 13) is formed on the ring member 55, the ring member 55 is further removed from the state where the contact portion 62 contacts the shaft end surface 21a. By screwing in, an axial stress can be generated between the ring member 55 (female screw 61) and the fixing portion 41 (male screw 43). Thereby, the boot 27 can be firmly attached to the rack housing 13. Further, since the abutting portion 62 contacts the shaft end surface 21a, a gap therebetween can be sealed, and even if a foreign matter passes between the main body portion 42 and the ring member 55, the foreign matter enters the rack housing 13. Can be suppressed.

(4) Since the ring member 55 is formed with the grip portion 63 protruding outward in the radial direction so as to be exposed from the outer peripheral surface of the coupling end portion 54, the ring member 55 can be directly gripped by a jig or the like, and easily. The boot 27 can be attached to the rack housing 13.

(5) Since the ring member 55 whose surface has been subjected to rust prevention treatment is used, it is possible to suppress the occurrence of rust on the ring member 55, and thus foreign matter can be introduced between the fixed portion 41 and the ring member 55. It is possible to suppress the passage and entry into the rack housing 13.

(Second embodiment)
Next, a second embodiment of the boot attachment structure will be described with reference to the drawings. For the sake of convenience of explanation, the same components are designated by the same reference numerals as those of the first embodiment, and the description thereof will be omitted.

As shown in FIG. 5, the seal portion 65 of the present embodiment is formed in an annular shape extending in the circumferential direction thereof, and is formed on the surface 71 facing the opening end portion 26 (step surface 44) of the seal portion 65. An open storage part 72 is formed. A sealing material 73 such as grease or a liquid gasket is filled in the storage portion 72. Then, the sealing material 73 flows out from the storage portion 72 in a state where the sealing portion 65 is compressed in the axial direction, and adheres to the step surface 44 and the facing surface 71.

Next, attachment of the boot 27 to the rack housing 13 will be described.
As shown in FIG. 6, in this embodiment, the boot 27 in which the storage member 72 is pre-filled with the seal material 73 is used, and the boot 27 is attached to the rack housing 13 as in the first embodiment. As a result, when the seal portion 65 is compressed in the axial direction, the seal material 73 flows out from the storage portion 72 and the boot material 27 is applied to the step surface 44 and the facing surface 71. It is attached to 13.

As described above, in the present embodiment, the following actions and effects are obtained in addition to the actions and effects similar to the actions and effects of (1) to (5) of the first embodiment.
(6) In the seal portion 65, the storage portion 72 is formed which is opened on the surface 71 of the opening end portion 26 facing the main body portion 42 and is filled with the seal material 73. Therefore, when the boot 27 is attached to the rack housing 13 and the seal portion 65 is axially compressed, the seal material 73 flows out from the storage portion 72, so that the seal material 73 is provided between the main body portion 42 and the seal portion 65. Sealed. Thereby, the sealing property can be further improved. Further, the sealing material 73 flows out from the storage portion 72 when the sealing portion 65 is compressed and seals between the main body portion 42 and the sealing portion 65. Therefore, for example, the facing surface 71 of the sealing portion 65 and the main body portion 42. It is possible to suppress the mounting work of the boot 27 from being complicated as compared with the case where the boot 27 is mounted after the sealing material 73 is applied to the step surface 44.

Each of the above embodiments can be modified and implemented as follows. The above embodiments and the following modifications can be implemented in combination with each other within a technically consistent range.
-In the said 2nd Embodiment, although the storage part 72 was formed in the sealing part 65 in annular shape, it is not restricted to this, for example, while forming the storage part 72 in a round hole shape, the sealing part 65 has a plurality of storage parts 72. May be formed, and its shape can be appropriately changed.

In each of the above embodiments, the ring member 55 may be one that has not been subjected to rustproofing.
In each of the above-described embodiments, the grip 63 has a two-sided width shape, but the shape is not limited to this and may be, for example, a hexagonal shape, and the shape can be appropriately changed. Further, the grip 63 may not be provided on the ring member 55.

-In each above-mentioned embodiment, it is not necessary to provide contact part 62 to ring member 55.
In the above embodiment, the boot 27 is attached to the rack housing 13 by screwing the ring member 55 to the fixing portion 41. However, the present invention is not limited to this, and the male screw 43 and the female screw 61 are not formed. The boot 27 may be attached to the rack housing 13 by press-fitting 55 onto the outer periphery of the fixed portion 41.

In the above-described embodiment, the outer diameter of the main body portion 42 of the opening end portion 26 is set to be larger than the outer diameter of the fixed portion 41, and the entire main body portion 42 is configured as a wall portion. The outer diameter of 42 and the outer diameter of the fixed portion 41 may be set to be substantially equal to each other, and an annular wall portion may be formed on the outer periphery of the main body portion 42.

The mounting structure of each of the above embodiments may be applied when the boot 27 is mounted on another mounting target such as the ball shaft 24 or the outer race of a constant velocity joint.

DESCRIPTION OF SYMBOLS 1... Steering device, 12... Rack shaft, 13... Rack housing (mounting object), 21... Cylindrical part, 21a... Shaft end face, 22... Ball joint, 26... Open end part, 27... Boots, 41... Fixed part, 42... Main body portion (wall portion), 43... Male screw, 44... Step surface, 51... Boot body, 52... Flexible portion, 53... Small diameter end portion, 54... Connection end portion, 55... Ring member, 55a... Shaft The other end surface in the direction, 61... Female screw, 62... Abutting portion, 63... Gripping portion, 65... Sealing portion, 71... Opposing surface, 72... Storage portion, 73... Sealing material.

Claims (6)

A boot attachment structure for attaching a boot to an opening end of a tubular portion in an attachment target,
The open end is
An annular fixing portion including an axial end surface on the one axial side of the tubular portion,
An annular wall portion that is provided on the other end side in the axial direction of the fixing portion and that protrudes radially outward from the outer peripheral surface of the fixing portion,
The boots are
A tubular flexible portion made of an elastic material, which is deformable in the axial direction of the tubular portion and in a direction intersecting the axial direction, and an annular connection provided on the other end side in the axial direction of the flexible portion. A boot body having an end portion,
Made of a metal material, and provided with an annular ring member provided on the inner circumference of the connecting end portion and fixed to the outer circumference of the fixing portion,
A boot mounting structure in which an annular seal portion that is axially compressed between the wall portion and the ring member is formed at the connecting end portion. The boot mounting structure according to claim 1,
A male screw is formed on the outer periphery of the fixing portion,
A boot mounting structure in which a female screw that is screwed into the male screw is formed on the inner circumference of the ring member. The boot mounting structure according to claim 2,
A boot mounting structure in which an abutting portion that abuts the shaft end surface is formed on the ring member. In the boot attachment structure according to any one of claims 1 to 3,
A boot mounting structure in which a grip portion that protrudes outward in the radial direction is formed on the ring member so as to be exposed from the outer peripheral surface of the connecting end portion. The boot attachment structure according to any one of claims 1 to 4,
The ring member is a boot mounting structure in which the surface of the ring member is subjected to rust prevention treatment. The boot mounting structure according to any one of claims 1 to 5,
A boot mounting structure in which a storage portion is formed in the sealing portion, the storage portion being opened on a surface of the sealing portion facing the wall portion and filled with a sealing material.