JP4395944B2 - Sealing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device used for a shaft sealing portion or the like of various devices that perform relative reciprocating movement such as a shock absorber of an automobile.
[0002]
[Prior art]
Conventionally, as this type of sealing device, for example, there is a device as shown in FIG.
[0003]
As shown in FIG. 4, the sealing device 101 is roughly composed of a rubber-like elastic seal portion 102 and a fixing portion 103 fixed to the housing 130.
[0004]
The fixing portion 103 includes a reinforcing ring 104 that prevents deformation of the fixing portion 103 and a rubber-like elastic body 105 that is integrally baked and fixed to the reinforcing ring 104.
[0005]
The reinforcing ring 104 is a cylindrical member having a cylindrical portion 104a and an inward flange portion 104b extending in the inner diameter direction at the atmosphere side A end of the cylindrical portion 104a. A rubber-like elastic body 105 is integrally baked and fixed continuously to the atmosphere-side A end surface of the inward flange portion 104b of the reinforcing ring 104, the outer peripheral surface of the cylindrical portion 104a, and the sealing target-side S end surface.
[0006]
In the fixing portion 103, the cylindrical portion 104 a of the reinforcing ring 104 is fitted and fixed to the inner peripheral surface of the housing 130 via a rubber-like elastic body 105.
[0007]
A rubber-like elastic seal portion 102 is provided at the inner end of the inward flange portion 104b of the reinforcing ring 104 of the fixed portion 103.
[0008]
The seal portion 102 is in contact with the shaft 120 and has a main lip 102A that prevents leakage of fluid sealed on the sealing target side S, and a dust lip 102B that prevents intrusion of dust such as dust ash and foreign matter from the outside. It is equipped with.
[0009]
On the back surface of the main lip 102A, a garter spring 102C is provided for holding a pressing force with which the main lip 102A contacts the surface of the shaft 120.
[0010]
The sealing device 101 is used in a shaft sealing portion such as a shock absorber of an automobile, and is slid and sealed on the shaft 120 in accordance with the axial reciprocation of the shaft 120.
[0011]
[Problems to be solved by the invention]
However, the conventional techniques as described above have the following problems.
[0012]
A Lissajous waveform as shown in FIG. 5 showing the relationship between the stroke S and the friction F is shown as a representation of the state of the sealing device 101. In this Lissajous waveform, the waveform is discontinuous at the top dead center and the bottom dead center of the stroke S. If there is a portion and the reciprocating distance of the shaft 120 is in a fine amplitude state of about ± 0.2 mm of reciprocation, the oil film cannot be replenished, causing the oil film to run out, and the main lip 102A is heated and worn due to this. As a result, there is a problem that the durability of the sealing device 101 is poor.
[0013]
Further, in the minute amplitude state, vibrations are continuously generated in a short time. Especially when the sealing device 101 is applied to a shock absorber of an automobile, the continuous vibrations improve the ride comfort of a person riding in the automobile. There was a problem to make it worse.
[0014]
The present invention has been made to solve the above-described problems of the prior art, and an object of the present invention is to provide a high-quality sealing device that improves durability in a minute amplitude state and prevents occurrence of vibration. There is to do.
[0015]
[Means for Solving the Problems]
In order to achieve the above object, the present invention seals an annular gap between two members that are provided coaxially and relatively reciprocally move in the axial direction, and seals one of the two members. In a sealing device provided with a seal portion that is in contact and used for a shock absorber, the seal portion is swingably supported by a waist portion having elasticity, and is rolled on one member as the two members move relative to each other. A rolling part having a rolling surface that is in close contact with, and a lip part that is provided on both sides in the axial direction of the rolling surface of the rolling part and that is in a state of being separated from or abutting against one member according to the posture of the rolling part; It is provided with.
[0016]
Therefore, when the relative movement of the two members does not contact the lip portion during the predetermined distance, the rolling surface of the rolling portion is in close contact with the one member while rolling, and the relative movement of the two members is longer than the predetermined distance. The lip portion comes into contact with one member to stop rolling of the rolling portion, and the lip portion and the rolling portion slide on one member in a state of being in contact with one member.
[0017]
As a result, if the relative movement of the two members is in a minute amplitude state shorter than a predetermined distance, the rolling surface of the rolling part rolls in accordance with the relative movement stroke of the two members to maintain a sealed state, and thus wears. The durability can be improved and the occurrence of continuous vibration can be prevented.
[0018]
It is preferable to generate a repulsive force in the waist that supports the seal portion that works to return the posture of the rolling portion to the original position as compared to the change in posture due to rolling of the rolling portion.
[0019]
As a result, the repulsive force increases as the rolling portion rolls, and the adhesion to one member also increases.
[0020]
It is preferable that the rolling portion is provided in an arc shape in cross section.
[0021]
Thereby, the rolling part can smoothly roll with respect to one member.
[0022]
It is preferably used for an automobile shock absorber.
[0023]
Thereby, in the minute amplitude state in which the relative movement of the two members is shorter than the predetermined distance, continuous vibration does not occur, and the riding comfort of the automobile can be improved.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.
[0025]
FIG. 1 is a diagram illustrating a sealing device according to an embodiment. In FIG. 1, a sealing device 1 is inserted into a housing and a housing as two members that are coaxially provided and reciprocally move in the axial direction at a shaft sealing portion of a shock absorber of an automobile as in the prior art. The annular gap between the shafts 3 is sealed.
[0026]
The sealing device 1 generally includes a seal portion 2 and a fixing portion that is fitted and fixed to the inner periphery of the housing.
[0027]
The seal portion 2 is made of a rubber-like elastic body from the inner end of the inward flange portion of the metal reinforcing ring of the fixed portion.
[0028]
In addition, about a fixing | fixed part, since a well-known technique is applied to the part fitted and fixed to the inner periphery of a housing like the thing similar to a prior art, description is abbreviate | omitted here and is a characteristic part of this Embodiment. The seal part 2 will be described in detail.
[0029]
The seal portion 2 includes a rolling portion 2A that comes into close contact with the shaft 3 and lip portions 2B1 and 2B2 provided on both sides in the axial direction of the rolling portion 2A.
[0030]
The rolling portion 2 </ b> A has a circular arc shape in the axial direction of the shaft 3, and is in close contact with the outer peripheral surface of the shaft 3 with the rolling surface having the circular arc shape in cross section. Then, in the reciprocating movement of the shaft 3 for a predetermined distance, the outer peripheral surface of the shaft 3 is rolled by the rolling surface of the rolling portion 2A, and the oil on the sealing target side S and the like are sealed by keeping in close contact with each other. To prevent leakage.
[0031]
At this time, the rolling portion 2A has a circular arc shape in section, so that the rolling surface of the rolling portion 2A can smoothly roll with respect to the shaft 3.
[0032]
Further, a lip portion 2B1 on the sealing object side S and a lip 2B2 on the atmosphere side A are provided on both axial sides of the rolling surface of the rolling portion 2A.
[0033]
The lip portions 2B1 and 2B2 are in a state of being separated from or in contact with the shaft 3 according to the posture of the rolling portion 2A. When the shaft 3 reciprocates a distance longer than a predetermined distance, the rolling portion 2A At the same time, it contacts the outer peripheral surface of the shaft 3 and slides in this state.
[0034]
That is, when the shaft 3 is reciprocating for a predetermined distance, the lip portions 2B1 and 2B2 are separated from the shaft 3, and the shaft 3 has reciprocated for a distance longer than the predetermined distance. Sometimes, the lip portions 2B1 and 2B2 abut on the shaft 3 to serve as stoppers for stopping the rolling portion 2A, and slide on the shaft 3 in a state where the rolling of the rolling portion 2A is stopped.
[0035]
Here, in order to smoothly perform the operation of the rolling portion 2A and the lip portion 2B, the waist portion 2C supporting the seal portion 2 for connecting the seal portion 2 to the fixed portion is not reinforced by the reinforcing ring extending from the fixed portion. It has become.
[0036]
Accordingly, the waist 2C is provided with such strength that the rolling part 2A rolls without sliding, and the followability of the rolling part 2A to the reciprocating movement of the shaft 3 is enhanced.
[0037]
Further, since the waist 2C is made of a rubber-like elastic body that is not reinforced by the reinforcing ring, the rolling portion 2A is moved to the original posture as the rolling portion 2A rolls from the center to either the atmosphere side A or the sealing target side S. The repulsive force to return to the pressure increases and the friction F is increased.
[0038]
Next, the state of the sealing device 1 according to the change of the stroke S will be described using the Lissajous waveform of FIG. 2 showing the relationship between the stroke S of the reciprocating movement of the shaft 3 and the friction F. The state of the sealing device 1 according to the change of the stroke S is shown for each state in FIG.
[0039]
First, when the sealing device 1 is mounted, the sealing device 1 is in close contact with the shaft 3 at the axial center of the rolling surface of the rolling portion 2A (state (1)).
[0040]
Next, when the shaft 3 starts to reciprocate and the shaft 3 starts to move to the atmosphere side A, the rolling surface of the rolling portion 2A rolls around the outer peripheral surface of the shaft 3 in accordance with the stroke S ((2) State).
[0041]
When the predetermined stroke S is exceeded, the lip 2B1 provided at the end of the sealing fluid side S of the rolling portion 2A comes into contact with the shaft 3, and the rolling of the rolling portion 2A stops. When the shaft 3 is further moved, the rolling portion 2A and the lip portion 2B1 are kept in contact with the shaft 3 and slide according to the stroke S of the shaft 3 (state (3)).
[0042]
When the stroke S of the shaft 3 is switched to the sealing target side S, the rolling portion 2A begins to roll in accordance with the stroke S, the lip portion 2B1 on the sealing target side S is separated from the shaft 3, and the rolling surface of the rolling portion 2A is the stroke. Roll along the outer peripheral surface of the shaft 3 in accordance with S (state (4)).
[0043]
Then, the lip portion 2B2 on the atmosphere side A comes into contact with the shaft 3, the rolling portion 2A stops, and the state in which the rolling portion 2A and the lip portion 2B2 are in contact with the shaft 3 is maintained to match the stroke S of the shaft 3. Slide (state (5)).
[0044]
When the stroke S of the shaft 3 is switched to the atmosphere side A, the lip portion 2B2 is separated from the shaft 3 and the rolling portion 2A begins to roll in accordance with the stroke S, and the rolling surface of the rolling portion 2A is aligned with the stroke S. 3 rolls around the outer peripheral surface (state (6)).
[0045]
Further, similarly to the state of (3), the state in which the rolling portion 2A and the lip portion 2B1 on the sealing target side S are in contact with each other and sliding according to the stroke S of the shaft 3 (the state of (7)) )
[0046]
Thereafter, the states (4) to (7) are repeated according to the reciprocating movement of the shaft 3.
[0047]
With the above configuration, in the present embodiment, when the reciprocating distance of the shaft 3 is in a minute amplitude state where the reciprocating motion is about ± 0.2 mm, the rolling surface of the rolling portion 2A is adjusted to the stroke S of the shaft 3. Since it rolls, the sealing device 1 is not worn and the durability can be improved.
[0048]
Further, since there is no continuous vibration in the minute amplitude state as in the prior art, particularly when the sealing device 1 of the present embodiment is applied to a shock absorber of an automobile, continuous vibration does not occur and the ride comfort of the automobile. Can be better.
[0049]
【The invention's effect】
As described above, according to the present invention, the seal portion is supported by the elastic waist portion so as to be swingable, and has a rolling surface that comes into close contact with the two members as the two members move relative to each other. And a lip portion that is provided on both sides in the axial direction of the rolling surface of the rolling portion and is in a state of being separated from or in contact with one member according to the posture of the rolling portion. If the movement is in a minute amplitude state shorter than a predetermined distance, the rolling surface of the rolling part rolls according to the relative movement stroke of the two members and maintains the sealed state, so that the durability is improved without being worn. As a result, continuous vibrations can be prevented.
[0050]
By generating a repulsive force that works to return the posture of the rolling part to the waist part that supports the seal part compared to the change of the posture due to the rolling part of the rolling part, the repulsive force increases as the rolling part rolls. Also, the adhesion to one member increases.
[0051]
Since the rolling portion is provided in an arc shape in cross section, the rolling portion can smoothly roll with respect to one member.
[0052]
By being used in a shock absorber for an automobile, continuous vibration does not occur in a minute amplitude state in which the relative movement of the two members is shorter than a predetermined distance, and the riding comfort of the automobile can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a sealing device according to an embodiment.
FIG. 2 is a diagram showing a relationship between stroke and friction of the sealing device according to the embodiment.
FIG. 3 is an explanatory view showing a state corresponding to a stroke of the sealing device according to the embodiment.
FIG. 4 is a cross-sectional view showing a prior art sealing device.
FIG. 5 is a diagram showing a relationship between stroke and friction of a conventional sealing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Seal part 2A Rolling part 2B1, 2B2 Lip part 2C Waist part 3 Axis

Claims (4)

It seals an annular gap between two members that are provided coaxially and move relatively reciprocally in the axial direction.
In the sealing device used for the shock absorber, comprising a seal portion that sealingly contacts one of the two members,
The seal portion is
While being supported swingably by the waist with elasticity,
A rolling part having a rolling surface that comes into close contact with one member while rolling relative to the two members;
A sealing device comprising: a lip portion provided on both axial sides of the rolling surface of the rolling portion, wherein the lip portion is in a state of being separated from or in contact with one member according to the posture of the rolling portion.   The repulsive force which works so that the posture of the rolling part may be returned compared with the change of the posture by rolling of the rolling part is generated in the waist part which supports the seal part. Sealing device.   The sealing device according to claim 1, wherein the rolling portion is provided in an arc shape in cross section.   The sealing device according to claim 1, 2, or 3, wherein the sealing device is used for a shock absorber of an automobile.

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