JP2001003973A - Dust cover of shock absorber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dust cover with excellent durability and productivity regarding its mounting. SOLUTION: The upper end 16 of this cover is attached to the piston rod 3 of a shock absorber 1. The lower end 18 of the cover is fastened and held by an attaching band 20 in a diameter-reducing direction while being slidably positioned on the outer periphery of a housing 2. In this mounted state, the inside diameter D1 of the lower end 18 of the cover is set to be greater than the outside diameter D3 of the housing 2 and smaller than the outside diameter D2 of a large-diameter flange part 5 provided at the upper end of the housing 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dust cover mounted on a shock absorber of a vehicle.

[0002]

2. Description of the Related Art Generally, a suspension device (vehicle suspension device) is provided between a tire side and a vehicle body side of a vehicle to appropriately absorb a shock from a road surface. A coil spring and a shock absorber for preventing sudden expansion and contraction of the coil spring to reduce vibration of the vehicle body are provided. This shock absorber is provided with a housing attached to the tire side, and a piston rod projecting from the upper end of the housing so as to be extendable and retractable and attached to the vehicle body at the upper end.

[0003] In such a shock absorber, a dust cover for covering the sliding portion between the housing and the piston rod is preferably attached so as to prevent water or dust from entering the sliding portion (actually open flat). No. 1-180035,
JP-A-6-53838). More specifically, the upper end of the cover is fixed to the outer peripheral surface of the piston rod, and the lower end of the cover is connected to the housing in order to secure airtightness in the dust cover and reliably prevent water or dust from entering. Is fastened and fixed to the outer peripheral surface using an appropriate mounting band.

[0004]

However, when the upper end of the cover is fixed to the piston rod and the lower end of the cover is fixed to the housing, the dust cover always expands and contracts with the movement of the piston rod. At the same time, the expansion / compression ratio of the dust cover increases, and the durability of the dust cover may be reduced.

[0005] If the airtightness inside the dust cover is too good, the pressure inside the dust cover increases when the dust cover is compressed and deformed, which adversely affects, for example, a sealing portion such as a sliding portion between the housing and the piston rod. There is a risk of giving. For this reason, it is necessary to take measures such as separately providing a hole for venting air in the dust cover.

[0006] The present invention has been made in view of such problems.

[0007]

SUMMARY OF THE INVENTION A dust cover according to the present invention is mounted on a shock absorber having a cylindrical housing and a piston rod that extends upward and downward from the upper end of the housing. The sliding portion with the rod is covered to prevent water, dust and the like from entering the sliding portion.

According to the first aspect of the present invention, in the mounted state, the upper end of the dust cover is attached to the piston rod, and the lower end of the dust cover is slidably disposed on the outer periphery of the housing.

Therefore, when the upper end of the cover moves in the axial direction together with the piston rod, the lower end of the cover can slide in the axial direction along the outer periphery of the housing. That is, the entire dust cover can move relative to the housing together with the piston rod. Therefore, the number of expansion / contraction of the dust cover and the expansion / compression ratio are suppressed, and the durability of the dust cover is improved.

[0010] In the above-mentioned mounting state, the inner diameter of the lower end of the cover is set to be larger than the outer diameter of the housing. For this reason, a predetermined radial gap can be secured between the inner peripheral surface of the lower end of the cover and the outer peripheral surface of the housing. As a result, the fluctuation of the internal pressure due to the expansion and contraction of the dust cover is avoided, and there is no possibility that the seal portion in the dust cover is adversely affected. In other words, there is no need to separately form an air vent hole in the dust cover.

The above-mentioned radial gap is set small enough so that water, dust and the like do not enter.

Further, in the above-mentioned mounting state, the inner diameter of the lower end of the cover is set to be smaller than the outer diameter of the large-diameter flange provided at the upper end of the housing. For this reason,
The lower end of the cover is locked to the large-diameter flange,
It does not come off the housing easily.

According to the second aspect of the present invention, in the above-described mounting state,
A mounting band is provided for tightening and holding the lower end of the cover in the radially reducing direction so that the lower end of the cover does not elastically deform in the radially expanding direction so as to get over the large diameter flange.
In this case, it is possible to more reliably prevent the lower end of the cover from coming off the housing.

[0014] According to the third aspect of the present invention, in the above attached state, the cover projects from the inner peripheral surface of the lower end of the cover toward the housing.
It is characterized in that the projections which are in sliding contact with the outer peripheral surface of the housing substantially without gaps are provided intermittently in the circumferential direction.

In this case, a radial gap corresponding to the height of the projection can be substantially uniformly provided between the inner peripheral surface of the lower end portion of the cover and the outer peripheral surface of the housing over the entire circumference. Further, since the lower end of the cover is intermittently slidably in contact with the outer peripheral surface of the housing at the projection, the sliding resistance with the outer peripheral surface of the housing can be effectively suppressed.

According to a fourth aspect of the present invention, at the lower end of the cover,
A plurality of gaps are provided intermittently in the circumferential direction in advance.

In this case, for example, when the lower end of the cover is tightened in the diameter reducing direction using the mounting band, the cover is appropriately held in a predetermined cylindrical shape when the lower end of the cover is reduced in diameter by the gap. As a result, excessive tightening of the lower end of the cover is suppressed, the workability of the mounting is remarkably improved, and the (inner diameter) dimension and shape of the lower end of the cover can be accurately and easily set in advance. .

Further, since the diameter of the lower end of the cover is enlarged in advance by the amount of the gap, and the lower end of the cover can be easily deformed in the diameter increasing direction, the lower end of the cover is attached at the time of mounting. It can be easily arranged on the outer periphery of the housing over the large-diameter flange portion.

According to a fifth aspect of the present invention, at the lower end of the cover,
A bent portion that protrudes inward in the radial direction is formed intermittently in the circumferential direction, and when the lower end portion of the cover is tightened in the radial direction with the mounting band, the bent portion is elastically deformed and the inner peripheral surface of the lower end portion of the cover is formed. From the housing to the housing side, and slides substantially without gaps on the outer peripheral surface of the housing.

At the bent portion, the gap is formed before mounting, and the projection is formed by elastic deformation in the mounted state. That is, by forming the bent portion, it is possible to realize the functions of both the gap portion and the projection portion described above.

[0021]

According to the present invention, since the lower end of the dust cover is slidably disposed on the outer periphery of the housing, the entire dust cover is slidable with respect to the housing together with the piston rod. As a result, the number of expansion / contraction of the dust cover and the expansion / compression ratio are suppressed, and the durability of the dust cover is improved.

Also, since a radial gap is formed between the inner peripheral surface of the lower end of the cover and the outer peripheral surface of the housing, the dust cover can be extended and retracted without forming a separate air vent hole in the dust cover. The accompanying change in internal pressure can be prevented, and there is no possibility that such a pressure change will adversely affect the seal portion or the like in the dust cover.

Furthermore, since the inner diameter of the lower end of the cover is set smaller than the outer diameter of the large-diameter flange provided at the upper end of the housing in the mounted state, the lower end of the cover is appropriately locked to the large-diameter flange. So that there is no danger of easily falling out of the housing.

[0024]

FIG. 1 is a sectional view showing an embodiment in which a dust cover 10 according to the present invention is applied to a strut type suspension device provided between a tire side and a vehicle body side of a vehicle.

This suspension device includes a coil spring (not shown) and a shock absorber 1 for preventing sudden expansion and contraction by the coil spring to reduce vibration of the vehicle body.
, And is roughly configured. The shock absorber 1 includes a cylindrical housing 2, a piston rod 3 that extends upward and downward from the upper end of the housing 2,
The lower end of the housing 2 is attached to the tire side, and the upper end of the piston rod 3 is attached to the vehicle body together with the upper spring seat 4 that receives the upper end of the coil spring. A large-diameter flange portion 5 having an outer diameter D2 larger than the outer diameter D3 of the housing 2 is provided at the upper end of the housing 2.

An elastically deformable dust cover 10 that covers at least a sliding portion (seal portion) S between the housing 2 and the piston rod 3 is attached to such a shock absorber 1. The dust cover 10 includes a relatively thick and small-diameter bumper portion 12 and a relatively thin and large-diameter cover body 14 connected to an outer peripheral portion of a lower end of the bumper portion 12.
, And is constituted. The bumper portion 12 and the cover main body 14 are integrally formed of, for example, the same elastic material such as rubber, or individually formed of different elastic materials, and are connected later.

The bumper portion 12 has a substantially cylindrical shape which is fitted on the outer periphery of the piston rod 3. The upper end surface of the bumper portion 12 is supported by the upper spring seat 4, and the lower end surface thereof can contact the upper end surface of the housing 2. They have a stopper function for elastically restricting the stroke range of the housing 2. The cover body 14 is formed in a bellows shape that can be easily expanded and contracted in the axial direction.

The dust cover 10 is inserted from the upper end of the piston rod 3 and attached to the shock absorber 1. Here, the cover upper end 16 of the dust cover 10 is attached to the outer periphery of the piston rod 3 with substantially no gap so as not to move relative to the piston rod 3 in the axial direction.

On the other hand, the lower cover 1 of the dust cover 10
Reference numeral 8 denotes a mounting state shown in FIG. More specifically, the lower end portion 18 of the cover is held in a state where it is appropriately tightened in the diameter reducing direction by an appropriate mounting band 20 such as an insul lock, a ratchet or the like. In addition, a flange portion 22 that protrudes radially outward is formed at the lowermost end of the cover lower end portion 18 so as to prevent the attachment band 20 from falling off.

In this mounting state, the inner diameter D1 of the cylindrical lower end portion 18 is larger than the outer diameter D3 of the housing 2, and the large-diameter flange portion 5 provided at the upper end of the housing 2 is provided. Is set to be smaller than the outer diameter D2.

FIG. 2 shows the lower end 1 of the cover according to the first embodiment.
8 is a cross-sectional view showing (a) a state before mounting and (b) a state after mounting. As shown in (a), a bent portion 24 projecting radially inward in a substantially V-shaped cross section is formed intermittently at four positions in the circumferential direction at the lower end portion 18 of the cover, thereby forming a predetermined portion. Gap portion 26 having a circumferential length of
Are formed intermittently in the circumferential direction.

Accordingly, the lower end portion 18 of the cover is
When tightening in the diameter reducing direction by 0, the opposing surfaces of the gap portion 26 come into contact with each other due to the elastic deformation of the bent portion 24, and the gap portion 26 substantially disappears, as shown in FIG. 18 is held in a predetermined cylindrical shape reduced in diameter by the gap 26. At this time, each bent portion 24 is elastically deformed to become a protrusion 28 projecting radially inward from the inner peripheral surface 18a of the lower end portion 18 of the cover.
The outer peripheral surface 2a is slidably slidably contacted with substantially no gap. That is, the lower end portion 18 of the cover has a predetermined inner diameter D1, and the projection 28 corresponds to the radial gap D4 between the inner peripheral surface 18a of the lower end portion 18 of the cover and the outer peripheral surface 2a of the housing 2 (FIG. 1). The shape, dimensions, and the like of the lower end portion 18 of the cover are set in advance so that the height of the cover lowers.

According to the dust cover 10 described above,
Since the cover lower end portion 18 is slidably disposed on the outer periphery of the housing 2, the cover lower end portion 18 is moved when the cover upper end portion 16 moves in the axial direction together with the piston rod 3.
Can slide in the axial direction along the outer periphery of the housing 2. That is, the entire dust cover 10 can move relative to the housing 2 together with the piston rod 3. As a result, the number of expansion / contraction of the dust cover 10 and the expansion / compression ratio are suppressed, and the durability of the dust cover 10 is improved.

1 and 2B, the inner diameter D1 of the lower end portion 18 of the cover is set to be larger than the outer diameter D3 of the housing 2 and the inner peripheral surface 18a of the lower end portion 18 of the cover. 28 projecting from the housing 2 to the housing 2 side
Are in sliding contact with the outer peripheral surface 2a of the housing 2 substantially without a gap, and thus correspond to the height of the protrusion 28 between the inner peripheral surface 18a of the cover lower end portion 18 and the outer peripheral surface 2a of the housing 2. The gap having the predetermined width D4 can be secured uniformly over the entire circumference. Therefore, without separately forming an air vent hole in the dust cover, a change in the internal pressure due to the expansion and contraction deformation of the dust cover 10 is avoided, and the dust cover 1 is removed.
There is no risk of adversely affecting the seal portion or the like in the area 0.

The width D4 of the radial gap is set sufficiently small so that water, dust and the like do not enter.

Further, in the above mounting state, the lower end 1 of the cover 1
8 is set smaller than the large-diameter flange portion 5 provided at the upper end of the housing 2, so that the lower end portion 18 of the cover is locked to the large-diameter flange portion 5 when the piston rod 3 is extended. , And does not come off the housing 2 easily.

In particular, the lower end portion 18 of the cover is
As a result, the cover lower end 18 is not elastically deformed in the radially expanding direction so as to get over the large-diameter flange portion 5, and the cover lower end 18 is separated from the housing 2. Detachment can be more reliably prevented.

In addition, since the lower end portion 18 of the cover is intermittently slidably in contact with the outer peripheral surface 2a of the housing 2 at the projection 28, the sliding resistance with the outer peripheral surface 2a of the housing 2 can be effectively suppressed. Can be.

In addition, since the gap 26 is previously provided intermittently in the circumferential direction at the lower end 18 of the cover,
When the cover lower end portion 18 is tightened in the diameter reducing direction by using 0, when the cover lower end portion 18 is reduced in diameter by the gap portion 26, the cover lower end portion 18 is appropriately held in a predetermined cylindrical shape. Excessive tightening of the lower end portion 18 is suppressed, and the workability of mounting the lower end portion 18 is remarkably improved, and the dimensions such as the inner diameter D1 of the cover lower end portion 18 after the diameter reduction can be accurately and easily set in advance.

The lower end portion 1 of the cover corresponds to the gap 26.
8 is expanded in advance, and the lower end 1 of the cover is
8 can be easily deformed in the diameter-enlargement direction.
And can be easily disposed on the outer periphery of the housing 2 so that the mounting workability is excellent.

FIG. 3 shows a cover lower end 1 according to a second embodiment.
It is sectional drawing which shows 8 '. This cover lower end 18 ′
The difference from the lower end portion 18 of the first embodiment is that the gap 26 'and the projection 28' are separately formed at different positions in advance.

In the first embodiment, the bent portion 2 formed at the lower end portion 18 of the cover is different from the second embodiment.
4 is a form having both functions of the gap 26 and the projection 28, and the configuration is further simplified.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an embodiment in which a dust cover according to the present invention is applied to a shock absorber.

FIGS. 2A and 2B show a lower end portion of a cover according to the first embodiment, and FIG.
FIG. 3B is a cross-sectional view before mounting, and FIG.

3A and 3B show a lower end portion of a cover according to a second embodiment, and FIG.
FIG. 3B is a cross-sectional view before mounting, and FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Shock absorber 2 ... Housing 3 ... Piston rod 5 ... Large diameter flange part 10 ... Dust cover 16 ... Cover upper end part 18 ... Cover lower end part 20 ... Mounting band 24 ... Bending part 26 ... Gap part 28 ... Projection part

Claims (5)

[Claims] 1. A cylindrical housing, a piston rod extending upward and retractably from an upper end of the housing,
An elastically deformable dust cover attached to a shock absorber having at least a sliding portion between the housing and the piston rod, the upper end of the dust cover is attached to the piston rod side, and the lower end of the dust cover is attached to the dust rod. In the mounted state slidably arranged on the outer periphery of the housing,
A dust cover for a shock absorber, wherein an inner diameter of a lower end portion of the cover is set to be larger than an outer diameter of the housing and smaller than an outer diameter of a large-diameter flange portion provided at an upper end of the housing. 2. The dust cover for a shock absorber according to claim 1, further comprising a mounting band that tightens and holds the lower end portion of the cover in a radially reduced direction in the mounted state. 3. In the mounting state, a protrusion protruding from the inner peripheral surface of the lower end of the cover toward the housing and slidingly contacting the outer peripheral surface of the housing with substantially no gap is provided intermittently in the circumferential direction. The dust cover of the shock absorber according to claim 1 or 2, wherein: 4. A plurality of gaps are provided intermittently in the circumferential direction at a lower end of the cover in advance.
3. The dust cover of the shock absorber according to any one of 3. 5. A bent portion projecting radially inward is formed intermittently in the circumferential direction at a lower end portion of the cover, and when the lower end portion of the cover is tightened in a radially reduced direction by a mounting band, the bent portion is formed. The dust cover for a shock absorber according to claim 1, wherein the dust cover is elastically deformed and protrudes from an inner peripheral surface of a lower end portion of the cover toward the housing, and slides on the outer peripheral surface of the housing with substantially no gap.