JP2016112990A - Boot attaching structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a boot attaching structure 50 keeping the seal performance of a boot for a long term.SOLUTION: A steering shaft 8 is inserted in a cylindrical housing 20, and supported so as to move in an axial direction X1. A fastened portion 35 of the cylindrical boot 30 is fitted with an outer peripheral seal portion 23 of an outer periphery 20a of a housing 20 and fastened by a fastening member 41. A boot end 34 of the boot 30 and the fastened portion 35 are connected through an extending portion 36. The outer periphery 20a of the housing 20 includes an annular stepped portion 24 opposite to the boot end 34 in the axial direction X1. The annular stepped portion 24 forms an annular storage recessed portion 25 for storing the boot end 34.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a boot mounting structure.

A rack and pinion type steering device is known as a steering device for automobiles and the like. This rack-and-pinion type steering device includes a pinion shaft that rotates by steering a steering wheel (handle), and a rack shaft that meshes with the pinion shaft and moves in the axial direction by the rotation of the pinion shaft.
The rack shaft is supported in a cylindrical housing so as to be movable in the axial direction. Both ends of the rack shaft protrude from the housing. In addition, tie rods are connected to both ends of the rack shaft via ball joints, respectively. The ends of the rack shaft and the ball joint are covered and protected by elastic bellows-like boots.

  One end of the boot is tightened to the outer peripheral seal part of the housing by the corresponding tightening band without a gap, and the other end of the boot is tightened to the outer peripheral seal part of the middle part of the tie rod without a gap by the corresponding tightening band. (For example, refer to Patent Document 1).

JP 2012-224274 A

Long-term use may cause corrosion of the outer periphery of the housing around one end of the boot, and the corrosion may reach the outer peripheral seal portion of the housing. In that case, the sealing performance of the boot with respect to the outer peripheral seal portion is lowered. For this reason, there is a possibility that air leaks from the boot inner space to the outside of the boot and the boot cannot be smoothly expanded and contracted.
An object of the present invention is to provide a boot mounting structure capable of maintaining boot sealing performance for a long period of time.

  The invention of claim 1 includes a cylindrical housing (20; 20Q) which includes an outer peripheral seal portion (23) on the outer periphery (20a), and is inserted through the steered shaft (8) so as to be movable in the axial direction (X1). ), A tightened portion (35) that is fitted to the outer peripheral seal portion and is tightened by a tightening member (41), and an extended portion (36; 36Q) from the tightened portion. And a cylindrical boot (30; 30P; 30Q) including a boot end (34; 34P; 34Q), and the outer periphery of the housing has an annular step portion (axially opposed to the boot end). 24; 24Q), and the annular step portion provides a boot mounting structure (50; 50P; 50Q) forming an annular receiving recess (25; 25Q) for receiving the boot end.

In addition, although the alphanumeric character in a parenthesis represents the corresponding component etc. in embodiment mentioned later, this does not mean that this invention should be limited to those embodiment as a matter of course. The same applies hereinafter.
According to a second aspect of the present invention, the boot end may be in contact with the bottom of the housing recess.
According to a third aspect of the present invention, the boot end may be in contact with the bottom of the housing recess in a pressed state.

The boot end may be press-fitted into the housing recess.
As in claim 5, the accommodation recess may be filled with grease (J).

  According to the first aspect of the present invention, the boot end is housed in the housing recess provided in the annular stepped portion on the outer periphery of the housing, thereby providing a labyrinth structure. Thus, moisture and the like are prevented from entering from the boot end side into the outer peripheral seal portion of the housing with which the boot tightening portion is fitted. As a result, the occurrence of corrosion at the outer peripheral seal portion is suppressed, so that the seal performance of the boot can be maintained for a long time.

According to invention of Claim 2, since the boot end is contact | abutting to the bottom of an accommodation recessed part, penetration | invasion of the water | moisture content etc. to the outer peripheral seal part side can be suppressed further.
According to the invention of claim 3, since the boot end is in contact with the bottom of the housing recess in a pressed state, it is possible to further suppress the entry of moisture and the like into the outer peripheral seal portion side.
According to the fourth aspect of the present invention, since the boot end is press-fitted into the housing recess, the intrusion of moisture or the like into the outer peripheral seal portion side can be further suppressed.

  According to the fifth aspect of the present invention, since the accommodation recess is filled with grease, it is possible to further suppress the entry of moisture and the like into the outer peripheral seal portion side.

It is a typical fragmentary sectional view showing a schematic structure of a steering device to which a boot attachment structure of a 1st embodiment of the present invention was applied. It is a partial cross-sectional enlarged view of the principal part of a steering device. It is an expanded sectional view of a boot attachment structure. It is an expanded sectional view of the boot attachment structure of a 2nd embodiment. It is an expanded sectional view of the boot attachment structure of a 3rd embodiment.

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings.
(First embodiment)
FIG. 1 is a schematic configuration diagram of a steering device 1 to which a boot mounting structure 50 according to a first embodiment of the present invention is applied. As shown in FIG. 1, the steering device 1 includes a steering shaft 3 connected to a steering member 2 such as a steering wheel, an intermediate shaft 5 connected to the steering shaft 3 via a universal joint 4, and an intermediate shaft 5. A rack shaft 8 as a steered shaft extending in the left-right direction of the automobile having a pinion shaft 7 connected to the vehicle through a universal joint 6 and a rack 81 meshing with a pinion 71 provided in the vicinity of the end of the pinion shaft 7 And have. The pinion shaft 7 and the rack shaft 8 constitute a steering mechanism A composed of a rack and pinion mechanism.

The rack shaft 8 is supported in a housing 20 fixed to the vehicle body through a plurality of bearings (not shown) so as to be capable of linear reciprocation in the axial direction X1. The housing 20 is made of, for example, an aluminum alloy or an iron alloy.
Each end 8 a of the rack shaft 8 protrudes from a corresponding housing end 21 of the housing 20. Each end portion 8 a of the rack shaft 8 is connected to one end portion 10 a of the corresponding tie rod 10 via a corresponding ball joint 9. The other end 10 b of each tie rod 10 is connected to a corresponding steered wheel 12 via a corresponding knuckle arm 11.

The steering device 1 includes a pair of cylindrical boots 30. Each boot 30 covers a part of the housing end 21, the end 8 a of the rack shaft 8, the ball joint 9 and the tie rod 10. The boot 30 is formed of a synthetic resin such as a polyolefin-based elastomer, and can be expanded and contracted.
Each boot 30 includes an annular first coupling portion 31 coupled to the outer periphery 20 a of the housing 20 and an annular second coupling portion 32 coupled to the outer periphery of the middle portion of the tie rod 10. Each boot 30 includes a bellows portion 33 in which peaks and valleys are alternately arranged between the connecting portions 31 and 32.

The first connecting portion 31 of each boot 30 is attached to the outer periphery 20 a of the corresponding end portion of the housing 20 using the boot attachment structure 50.
When the steering member 2 is operated and the steering shaft 3 is rotated, this rotation is converted into a linear motion in the axial direction X1 of the rack shaft 8 by the pinion 71 and the rack 81. Thereby, the turning of the steered wheel 12 is achieved. Further, with the movement of the rack shaft 8 in the axial direction X1, one of the boots 30 is extended, and the other boot 30 is shortened. At this time, the bellows portion 33 of the boot 30 flexibly expands and contracts to follow the movement of the rack shaft 8.

As shown in FIG. 2, the first connecting portion 31 of the boot 30 is attached to the outer periphery 20 a of the housing 20 using a corresponding fastening member 41. Further, the second connecting portion 32 of the boot 30 is attached to the outer periphery of the middle portion of the tie rod 10 using the corresponding fastening member 42.
As shown in FIG. 2 and FIG. 3, which is an enlarged view of the boot mounting structure 50, the outer periphery 20 a of the housing 20 forms an annular wall 22 at a position spaced apart from the housing end 21 in the axial direction X1 by a predetermined distance. On the outer periphery 20 a of the housing 20, an outer peripheral seal portion 23 formed of an annular groove is formed between the housing end 21 and the annular wall 22.

The annular wall 22 has an annular step 24 opposed to the boot end 34 of the boot 30 in the axial direction X <b> 1, and the annular step 24 forms an annular accommodating recess 25 that accommodates the boot end 34. . A slight gap is formed between the boot end 34 and the bottom of the housing recess 25.
A labyrinth structure for improving the sealing performance is formed by housing the boot end 34 in the housing recess 25. The accommodating recess 25 is filled with a lubricant J (see FIG. 3) such as grease.

The first connecting portion 31 of the boot 30 includes a tightened portion 35 that is tightened to the outer peripheral seal portion 23 of the housing 20 by a tightening member 41 that is a tightening band, for example. The tightened portion 35 is an annular convex portion that protrudes inward in the radial direction of the boot 30, and is an annular convex portion that is fitted to the outer peripheral seal portion 23 formed of an annular groove.
The boot 30 includes an annular extending portion 36 that extends from the tightened portion 35 to the boot end 34. The extending portion 36 is for increasing the distance from the boot end 34 to the tightened portion 35 (outer peripheral seal portion 23).

According to the first embodiment, the boot end 34 of the boot 30 is accommodated in the annular accommodating recess 25 provided in the annular step portion 24 of the outer periphery 20a of the housing 20 to exhibit a labyrinth structure. Thereby, moisture or the like is suppressed from entering the outer peripheral seal portion 23 of the housing 20 into which the tightened portion 35 of the boot 30 is fitted from the boot end 34 side.
As a result, it is possible to maintain the sealing performance of the boot 30 for a long time by suppressing the occurrence of corrosion of the outer peripheral seal portion 23.

  Moreover, since the accommodation recess 25 is filled with the lubricant J (grease), it is possible to further suppress the intrusion of moisture or the like into the outer peripheral seal portion 23 side. Furthermore, since the lubricant J is filled in the labyrinth structure portion formed by housing the boot end 34 in the housing recess 25, the lubricant J can be held for a long time. For this reason, the sealing performance of the boot 30 can be maintained for a long time.

Further, since the distance from the boot end 34 to the tightened portion 35 (the outer peripheral seal portion 23) is increased by the extending portion 36, the effect of suppressing moisture intrusion from the boot end 34 side to the outer peripheral seal portion 23 is achieved. Is expensive.
In the present embodiment, the lubricant J (grease) may be eliminated.
(Second Embodiment)
FIG. 4 is an enlarged cross-sectional view of a boot mounting structure 50P according to the second embodiment of the present invention.

The boot mounting structure 50P of the second embodiment in FIG. 4 is different from the boot mounting structure 50 of the first embodiment in FIG. 3 in that the boot end 34P of the boot 30P is the receiving recess 25 of the annular step 24 of the housing 20. It is the point which has contact | abutted at the bottom. Thereby, the penetration | invasion of the water | moisture content etc. to the outer peripheral seal part 23 side can be suppressed further.
The boot end 34P may be in contact with the bottom of the housing recess 25 by zero touch, or may be in contact in a pressed state. When the boot end 34P is brought into contact with the bottom of the housing recess 25 in the pressed state as in the latter case, it is possible to further suppress the entry of moisture or the like into the outer peripheral seal portion 23 side.

Further, when the boot end 34P comes into contact with the bottom of the housing recess 25, the tightened portion 35 made of an annular convex portion of the boot 30P is assembled to the outer peripheral seal portion 23 made of an annular groove with high positional accuracy. Thereby, the fall of the sealing performance resulting from the assembly | attachment failure of the boot 30P can be suppressed.
In the constituent elements of the second embodiment of FIG. 4, the same constituent elements as those of the first embodiment of FIG. 3 are denoted by the same reference numerals as the constituent elements of the first embodiment of FIG. is there.

In the present embodiment, the lubricant J (grease) may be eliminated.
(Third embodiment)
FIG. 5 is an enlarged cross-sectional view of a boot mounting structure 50Q according to the third embodiment of the present invention.
The boot mounting structure 50Q of the third embodiment of FIG. 5 is different from the boot mounting structure 50 of the first embodiment of FIG. 3 in that at least a part of the extended portion 36Q of the boot 30Q and the boot end 34Q are a housing. The 20Q annular stepped portion 24Q is press-fitted into the receiving recess 25Q. Thereby, the penetration | invasion of the water | moisture content etc. to the outer peripheral seal part 23 side can be suppressed further.

In the constituent elements of the third embodiment in FIG. 5, the same constituent elements as those in the first embodiment in FIG. 3 are denoted by the same reference numerals as those in the first embodiment in FIG. is there.
In the third embodiment, the boot end 34Q may or may not contact the bottom of the housing recess 25Q of the housing 20Q as shown. Further, the accommodation recess 25Q may be filled with a lubricant such as grease, or may not be filled.

  The present invention is not limited to the embodiments described above, and various modifications can be made within the scope of the claims of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Steering device, 2 ... Steering member, 3 ... Steering shaft, 7 ... Pinion shaft, 8 ... Rack shaft (steering shaft), 9 ... Ball joint, 10 ... Tie rod, 11 ... Knuckle arm, 12 ... Steering wheel, 20 20P; 20Q ... housing, 20a ... outer periphery, 21 ... housing end, 22; 22Q ... annular wall, 23 ... outer peripheral seal, 24; 24Q ... annular step, 25; 25Q ... accommodating recess, 30; 30P; 30Q ... Boot 31, first connecting portion 32, second connecting portion 33, bellows portion 34, 34 P; 34 Q, boot end, 35, tightened portion, 36, 36 Q, extending portion, 50, 50 P, 50 Q ... Boot mounting structure, J ... Lubricant (grease), X1 ... Axial direction

Claims (5)

A cylindrical housing that includes an outer peripheral seal portion on the outer periphery and supports the steered shaft so as to be movable in the axial direction;
A cylindrical boot including a tightened portion that is fitted to the outer peripheral seal portion and is tightened by a tightening member, and a boot end that is connected from the tightened portion via an extended portion. Prepared,
The outer periphery of the housing includes an annular step portion that is axially opposed to the boot end,
The annular mounting portion is a boot mounting structure in which an annular accommodating recess for accommodating the boot end is formed.   The boot mounting structure according to claim 1, wherein the boot end is in contact with a bottom of the housing recess.   The boot mounting structure according to claim 2, wherein the boot end is in contact with the bottom of the housing recess in a pressed state.   4. The boot mounting structure according to claim 1, wherein the boot end is press-fitted into the housing recess. 5.   The boot mounting structure according to any one of claims 1 to 4, wherein the accommodation recess is filled with grease.

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