JP2001304416A - Seal structure of boots - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely seal the periphery of a through hole by a pair of inner/outer annular seal lips protrusively provided in the periphery of the through hole in a boots side wall. SOLUTION: A pair of inner/outer annular seal lips 17, 18 coaxial to each other are protrusively provided in the periphery of a through hole 16 provided in a side wall of boots 10, also a protrusive height of one seal lip 17 of these annular seal lips is made higher than a protrusive height of the other seal lip 18. In this way, when an air-tight seal is formed by compressing a pair of the inner/outer annular seal lips 17, 18 in an axial line direction of the through hole 16, timing of a pair of the inner/outer annular seal lips 17, 18 respectively compressed to start deformation can be deviated, consequently a pair of the inner/outer annular seal lips 17, 18 are prevented from repulsing each other in a radial direction, so that high seal performance can be ensured by most suitably controlling this deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a seal structure for a boot mounted on, for example, a steering gear box of an automobile, and more specifically, a pair of inner and outer annular seal lips are provided around a through hole formed in a side wall of the boot. The present invention relates to a boot seal structure.

[0002]

2. Description of the Related Art Conventionally, there is a type of steering apparatus of a vehicle called a center take-off type. In a boot for sealing a steering gear box of this type of steering apparatus, a through hole formed in a side wall thereof is provided. In order to connect the tie rod to the rack, it is necessary to securely seal the dust and muddy water through the through hole so as not to enter the steering gear box.

[0003] The structure of such a steering gear box and a boot will be briefly described with reference to FIGS. 6 to 10. Referring to FIG. 3 is slidably housed. And
A pair of left and right tie rods 5L, 5R are provided at the center in the longitudinal direction of the rack 3 via a pair of left and right bolts 4L, 4R.
Are attached. Further, the housing 2 is provided with a through hole 2a extending in the left-right direction in the figure to allow reciprocating movement of a pair of left and right bolts 4L and 4R.

A boot 6 for sealing the steering gear box 1 having such a structure is provided with a pair of left and right bolts 4L, 4L.
R and the like, a substantially cylindrical central portion 6a which reciprocates in the left and right direction in the figure, and a pair of left and right bolts 4L, 4
A pair of left and right bellows 6b, 6c allowing reciprocation of R and the like;
And a pair of left and right fixing portions 6 for fixing the boot 6 to the housing 2 by a boot band (not shown).
d, 6e.

As shown in an enlarged view in FIG. 7, a pair of left and right through holes 6f, 6f through which a pair of left and right bolts 4L, 4R and a collar 7 are inserted are formed in the center 6a of the boot 6. I have. And a pair of these left and right through holes 6f,
As shown in FIGS. 9 and 10 in an enlarged manner, 6f is fitted on the outer peripheral surface 7b of the step 7a of the pair of left and right collars 7, respectively.

At this time, the pair of left and right through-holes 6f, 6f are hermetically sealed to prevent dust and muddy water from entering the inside of the boot 6.
As shown in FIG. 8, a pair of inner and outer annular seal lips 6g, 6h coaxial with the through hole 6f are provided around the outer peripheral surfaces 6i of the central portion 6a of the boot 6, respectively, around the f, 6f.

[0007] When the tie rods 5L, 5R are fixed by tightening the bolts 4L, 4R, the seal lips 6g, 6h, as shown in FIG.
Bush 8 which is in close contact with the step 7a of the
Is compressed in the axial direction of the through hole 6f to a size equal to the step size L of the collar 7 by the lower surface 8a. As a result, the pair of inner and outer annular seal lips 6g and 6h
And the bush 8, so that a pair of left and right through holes 6
The periphery of f and 6f can be hermetically sealed.

[0008]

However, in the boot 6 described above, the protruding heights of the pair of inner and outer annular seal lips 6g and 6h are both equal (H1) as shown in FIG. . Thereby, the bolts 4L, 4R
Is gradually tightened, as shown in FIG. 9, the lower surface 8a of the bush 8 becomes a pair of inner and outer annular seal lips 6g, 6g.
h at the same time. Then, a pair of inner and outer annular seal lips 6g and 6h are
And gradually repel each other in the radial direction (left and right directions in the figure) as shown by the black arrows in FIG.

At this time, the inner annular seal lip 6g
Since it is fitted on the outer peripheral surface 7b of the collar 7, it is deformed radially outward, that is, toward the outer annular seal lip 6h. As a result, in the boot 6 described above, the outer annular seal lip 6h may be pushed down by the inner annular seal lip 6g and fall outward in the radial direction (leftward in the drawing). There was a case where the sealing performance for hermetically sealing decreased.

On the other hand, a pair of inner and outer annular seal lips 6g,
If only one annular sealing lip is used in order to avoid the above-mentioned problem occurring in 6h, the sealing performance for hermetically sealing the space between the collar 7 and the bush 8 is greatly reduced.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems of the prior art and to reliably seal the periphery of the through hole with a pair of inner and outer annular sealing lips protruding around the through hole in the boot side wall. It is an object of the present invention to provide a seal structure of a boot that can perform the following.

[0012]

According to the present invention, there is provided a seal structure for a boot, which comprises a pair of inner and outer annular seal lips coaxial with each other around a through hole formed in a side wall of the boot. A boot seal structure that protrudes from a side surface and that hermetically seals the space between the pair of sealed members by compressing the pair of inner and outer annular seal lips in the axial direction of the through hole by the pair of sealed members. The projecting height of one of the pair of inner and outer annular seal lips is made higher than the projecting height of the other seal lip.

That is, according to the boot seal structure of the present invention, when the pair of inner and outer annular seal lips are compressed in the axial direction of the through hole by the pair of sealed members,
First, the annular seal lip having the higher protruding height is compressed and starts deforming, and then the annular seal lip having the lower protruding height is compressed and starts deforming. Thus, according to the present invention, the timing at which the pair of inner and outer annular seal lips starts to be compressed and deformed can be shifted, so that the pair of inner and outer annular seal lips do not repel each other in the radial direction. High sealing performance can be ensured by optimally controlling the deformation.

[0014] Preferably, of the pair of inner and outer annular seal lips, the projecting height of the inner annular seal lip near the periphery of the through hole is made higher than the projecting height of the outer annular seal lip. That is, since the inner annular seal lip near the peripheral edge of the through hole has a higher degree of freedom of deformation when compressed in the axial direction of the through hole, the deformation of the pair of inner and outer annular seal lips is utilized by utilizing this fact. Optimal control and high sealing performance can be ensured.

More preferably, of the pair of inner and outer annular seal lips, an inner annular seal lip near the periphery of the through hole is externally fitted to at least one of the pair of sealed members. That is, when the inner annular seal lip near the periphery of the through hole is compressed in the axial direction of the through hole, the inner annular seal lip is also deformed radially inward with respect to the axis of the through hole. At this time, if the inner annular seal lip is externally fitted to one of the members to be sealed, a radial seal can be formed between the inner annular seal lip and the member to be sealed.

[0016] More preferably, on the side surface of the side wall opposite to the side on which the pair of inner and outer annular seal lips protrude, a meat steal portion recessed toward the base end side of the pair of inner and outer annular seal lips. To form Thereby, deformation when the pair of inner and outer annular seal lips are compressed in the axial direction of the through hole is optimally controlled, and higher sealing performance can be secured.

The seal structure of the boot according to the present invention is made by blowing a synthetic resin material such as a thermoplastic elastomer such as polyolefin, polyester, polyurethane, polyamide or styrene and a high polymerization degree polyvinyl chloride. The present invention can be applied to boots formed by molding or injection blow molding.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a seal structure for a boot according to the present invention will be described below in detail with reference to FIGS. Here, FIG. 1 is an overall vertical sectional view of a boot to which a boot seal structure according to an embodiment of the present invention is applied, FIG. 2 is a plan view showing a through hole of the boot shown in FIG. 1, and FIG. FIG. 4 is a sectional view taken along the line III-III shown in FIG. 3, FIG. 4 is an enlarged sectional view showing a state where compression of the annular seal lip shown in FIG. 3 is started, and FIG. 5 is an annular seal shown in FIG. It is a principal part expanded sectional view which shows the sealing state which compressed the lip. In the following description, the same reference numerals are used for the same portions as those of the above-described conventional technology, and the description is omitted.
In the following description, the direction in which the axis of the through hole provided in the side wall of the boot extends is referred to as the axial direction, and the direction perpendicular to the axis is referred to as the radial direction.

The boot 10 shown in FIG. 1 to which the seal structure of the boot of this embodiment is applied is manufactured by blow molding a polyester-based elastomer material, and is provided with a center take-off type steering gear box shown in FIG. 1
It is to be attached to. The boot 10 has a substantially cylindrical central portion 11 reciprocating in the left-right direction integrally with the pair of left and right bolts 4L, 4R and the pair of left and right collars 7 shown in FIG. , 13 and a pair of right and left fixing portions 14, 1 for fixing the boot 10 to the housing 2 using a boot band (not shown).
5 is provided.

As shown in FIG. 2, a pair of left and right bolts 4L and 4R and a pair of right and left collars 7 in FIG. 6 are inserted through the side wall forming the central portion 11 of the boot 10, respectively. Pair of left and right through holes 1 for
6, 16 are respectively penetrated. These through holes 16, 16 are externally fitted to the outer peripheral surface 7b of the step 7a of each collar 7, as shown in an enlarged manner in FIGS.

The outer surface 11a of the boot center 11
In the portions around the pair of left and right through holes 16, 16, FIG.
As shown in FIG.
8 project from the through-hole 16 coaxially. At this time, assuming that the protruding height of the inner annular seal lip 17 is H2 and the protruding height of the outer annular seal lip 18 is H3, H2> H3, and the inner annular seal lip 17
Is higher than the protruding height of the outer annular seal lip 18.

Further, a portion of the inner surface 11b of the center portion 11 of the boot 10 facing the pair of inner and outer annular seal lips 17, 18 is provided at a portion facing the pair of inner and outer annular seal lips 17, 1.
Meat stealing portions 17a, 18 recessed toward the base end of
a is formed.

Next, the function and effect of the above-described boot seal structure of the present embodiment will be described with reference to FIGS.

When the pair of inner and outer annular sealing lips 17 and 18 of the boot 10 are compressed in the axial direction by the collar 7 and the bush 8, as shown in FIG. The seal lip 17 is compressed and starts to deform, and then the outer annular seal lip 18 having a low protruding height is compressed and starts to deform. This makes it possible to shift the timing at which the pair of inner and outer annular seal lips 17 and 18 starts to be compressed and deformed, respectively. Therefore, like the conventional boot 6 shown in FIG. They do not repel each other in the radial direction. Therefore, unlike the conventional boot 6 shown in FIG. 10, it is possible to reliably prevent the outer annular seal lip 18 from being tilted outward in the radial direction by the inner annular seal lip 17, thereby impairing the sealing performance. it can.

The inner annular seal lip 17 is fitted on the outer peripheral surface 7b of the step 7a of the collar 7. Thus, when the inner annular seal lip 17 is compressed in the axial direction, the inner annular seal lip 17 is deformed radially inward toward the outer peripheral surface 7b of the collar 7 and closely adheres to the outer peripheral surface 7b of the collar 7. A radial seal can be formed between the inner annular sealing lip 17 and the collar 7.

Further, when the pair of inner and outer annular sealing lips 17 and 18 are compressed in the axial direction, the meat stealing portions 17a and 18a provided on the inner surface 11b of the central portion 11 of the boot 10 are provided with a collar as shown in FIG. The deformation of the pair of inner and outer annular seal lips 17 and 18 is optimally controlled while being in close contact with the step 7a.

Therefore, according to the boot seal structure of this embodiment, a pair of inner and outer annular seal lips 17 and 18 projecting around the through hole in the boot side wall is used to cover the periphery of the through hole 16 provided in the side wall of the boot. Sealing can be performed reliably.

As mentioned above, one embodiment of the seal structure of the boot according to the present invention has been described in detail. However, it is needless to say that the present invention is not limited to the above-described embodiment, and various modifications are possible. For example, in the above-described embodiment, the inner annular seal lip 17 is externally fitted to the outer peripheral surface 7b of the collar 7, and the protruding height of the inner annular seal lip 17 is higher than that of the outer annular seal lip. are doing. On the other hand, depending on the combination shape of the collar 7 and the bush 8, the outer annular seal lip 18 is externally fitted to either the collar 7 or the bush 8, and the projecting height of the outer annular seal lip 18 is reduced. It can also be higher than that of the inner annular sealing lip 17. Further, it goes without saying that the boot seal structure according to the present invention can be applied not only to synthetic resin boots but also to rubber boots.

[0029]

As is apparent from the above description, the seal structure for a boot according to the present invention has a pair of inner and outer annular seal lips which are coaxial with each other and protrude around a through hole provided in a side wall of the boot. One of the pair of inner and outer annular lips has a projecting height higher than that of the other sealing lip. This allows
When the pair of inner and outer annular seal lips are compressed in the axial direction of the through hole to form a hermetic seal, the timing at which the pair of inner and outer annular seal lips begin to be compressed and deformed can be shifted, so that the inner and outer pair of annular seal lips can be shifted. The annular seal lips do not repel each other in the radial direction, and their deformation can be optimally controlled to ensure high sealing performance.

[Brief description of the drawings]

FIG. 1 is an overall vertical sectional view of a boot to which a boot seal structure according to an embodiment of the present invention is applied.

FIG. 2 is a plan view showing a through hole of the boot shown in FIG. 1;

FIG. 3 is a sectional view taken along the line III-III shown in FIG. 2;

FIG. 4 is an enlarged sectional view of a main part showing a state where compression of the annular seal lip shown in FIG. 3 has started.

FIG. 5 is an enlarged sectional view of a main part showing a sealed state in which the annular seal lip shown in FIG. 3 is compressed.

FIG. 6 is a fragmentary side view showing a center take-off type steering device and a conventional boot.

FIG. 7 is an enlarged sectional view showing a main part of FIG. 6;

FIG. 8 is an enlarged sectional view showing a main part of the boot shown in FIGS. 6 and 7;

9 is an enlarged sectional view of a main part showing a state where compression of the annular seal lip shown in FIG. 8 has started.

FIG. 10 is an enlarged sectional view of a main part showing a sealing state in which the annular seal lip shown in FIG. 8 is compressed.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Steering gear box 2 Housing 3 Rack 4L, 4R bolt 5L, 5R Tie rod 7 Collar 8 Bush 10 Boot to which the present invention is applied 11 Central part 12, 13 Bellows part 14, 15 Fixing part 16 Through hole 17 Inner annular seal lip 17a Meat Stealing part 18 Outer annular seal lip 18a Meat stealing part

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yutaka Sasaki 112-1, Hagadai, Haga-cho, Haga-gun, Tochigi Pref. Inside the Showa Tochigi Development Center Co., Ltd. (72) Inventor Takuya Yoshino 1-12 Shiba-Daimon, Minato-ku, Tokyo No. 15 Nippon Mektron Co., Ltd. (72) Inventor Tsuyoshi Sato 1-12-15 Shiba Daimon, Minato-ku, Tokyo F-term in Nippon Mektron Co., Ltd. 3J040 AA01 AA12 BA01 EA02 EA15 FA05 HA15

Claims (5)

[Claims] 1. A pair of inner and outer annular seal lips projecting from one side of the side wall around a through hole formed in a side wall of a boot, and a pair of inner and outer annular seals are provided by a pair of sealed members. A seal structure of a boot that hermetically seals a space between the pair of sealed members by compressing a lip in an axial direction of the through-hole, wherein one of the pair of inner and outer annular seal lips projects. A boot seal structure, wherein the height is higher than the protruding height of the other seal lip. 2. A pair of inner and outer annular seal lips,
The seal structure for a boot according to claim 1, wherein a protruding height of an inner annular seal lip near a peripheral edge of the through hole is higher than a protruding height of an outer annular seal lip. 3. A pair of inner and outer annular seal lips,
The boot seal structure according to claim 1, wherein an inner annular seal lip near a periphery of the through hole is externally fitted to at least one of the pair of sealed members. 4. A stealth portion recessed toward a base end of the pair of inner and outer annular seal lips is formed on a side surface of the side wall opposite to a side where the pair of inner and outer annular seal lips protrudes. The seal structure for a boot according to any one of claims 1 to 3, wherein: 5. The seal structure for a boot according to claim 1, wherein said boot is formed from a synthetic resin material.