JP2000074224A - Seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seal with which warping can be simply determined in accordance with an insertion force with which a shaft is inserted in the seal, and which can be cured from the warping. SOLUTION: A seal 1 has a lip which is made of an elastic material and which has an inner surface 2a made into elastic contact with the peripheral surface 3a of a shaft 3 in the normal condition and an outer surface 2b adapted to be made into elastic contact with the same when the lip 2 is warped. A frictional coefficient 3a of the inner surface and a friction coefficient of the outer surface are different from each other with respect to the peripheral surface 3a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lip-type seal used for a sealing portion of various devices.

[0002]

2. Description of the Related Art Conventionally, oil seals, G seals and the like having a lip made of an elastic member such as rubber have been known. This type of seal assures a seal against one of the two regions separated by the lip by allowing the inner surface of the lip to adhere to the peripheral surface of the shaft while allowing the shaft to move.

[0003]

By the way, as a method of mounting this lip-shaped seal on a shaft, for example, Japanese Patent Application No. 9-90980
No. 339116 and Japanese Patent Application No. 9-339119 have already disclosed, but in such a seal insertion method, it is determined whether or not the lip is in a normal state, that is, whether or not the lip is turned up, by sealing the shaft. Because the lip is in a normal state and its inner surface is in elastic contact with the shaft peripheral surface, it is in a turned-up state and its outer surface is in elastic contact with the shaft peripheral surface. However, the above-described conventional seal, in which there is no large difference in insertion resistance, is not always easy to determine.

[0004] On the other hand, a seal for reliably determining whether the lip is turned up is described in, for example, Japanese Utility Model Registration No. 300744.
No. 6 (Japanese Utility Model Application No. 6-10536), this invention has its effect only under large-scale facilities, and means for inserting so as not to be turned up, and for facilitating turning back. Since the means is not described, it is desirable to adopt the above-described method of inserting the seal when attaching the seal to the shaft.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and makes it easy to determine whether the lip is turned up based on the insertion force when the shaft is inserted into the seal, and to easily return the turned up. It is an object of the present invention to provide a seal that can be used.

[0006]

In order to solve the above-mentioned problems, the invention according to claim 1 is a seal provided with a lip made of an elastic member, wherein the lip elastically contacts an outer peripheral surface of a shaft in a normal state. And an outer surface elastically contacted when the lip is turned up, wherein a friction coefficient of the inner surface with respect to the peripheral surface is different from a friction coefficient of the outer surface with respect to the peripheral surface.

According to a second aspect of the present invention, in the first aspect of the present invention, a friction coefficient of the outer surface with respect to the peripheral surface is larger than a friction coefficient of the inner surface with respect to the peripheral surface.

[0008] The invention of claim 3 is characterized in that, in the invention of claim 2, the surface roughness of the outer surface is larger than the surface roughness of the inner surface.

According to a fourth aspect of the present invention, in the second aspect, a lubricant is applied to the inner surface.

[0010] The invention of claim 5 is the invention of claims 1 to 3.
The invention according to any one of the first to third aspects, wherein the outer surface is formed of a member different from the inner surface.

According to a sixth aspect of the present invention, there is provided a seal including a lip made of an elastic member, wherein the lip has an inner surface which is in elastic contact with a peripheral surface of a shaft in a normal state, and an outer surface which is opposite to the inner surface. A rib is formed on the outer surface so as to elastically contact the peripheral surface when the lip is turned up.

According to a seventh aspect of the present invention, in the sixth aspect of the present invention, the rib is extended along a circumferential direction so that the height of the rib is not uniform.

The invention of claim 8 is characterized in that, in the invention of claim 6, the rib is formed so as to extend in the circumferential direction while meandering.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

[0015]

Embodiment 1 In FIGS. 1 and 2, reference numeral 1 denotes a seal according to the present invention. The seal 1 is annularly and integrally formed of an elastic member such as rubber, and has a lip 2 on its inner peripheral side.
Is provided so as to be inclined.

The shaft 3 is inserted through the seal 1 as shown in FIG. 3, and the inner surface 2a of the lip 2 is in a normal mounting state (hereinafter referred to as "normal state") as shown in FIG. It comes into contact with the peripheral surface 3 a of the shaft 3. The inner surface 2a is in close contact with its peripheral surface 3a while permitting rotation or reciprocation of the shaft 3, thereby ensuring sealing of one of the two regions 4, 5 separated by the lip 2.

The outer surface 2b of the lip 2 forming the front and back sides with the inner surface 2a
Is formed such that its surface roughness is larger than that of the inner surface 2a. Due to this difference in surface roughness, the friction coefficient of the outer surface 2b with respect to the peripheral surface 3a of the shaft 3 is reduced.
Is larger than the friction coefficient of the inner surface 2a with respect to.

In this case, the seal 1 is disclosed in Japanese Patent Application No. 9-339.
The shaft 3 is attached to the shaft 3 by the seal insertion method disclosed in Japanese Patent No. 116, and it is determined whether or not the lip 2 is turned up based on the insertion force when the shaft 3 is inserted into the seal 1. That is, when the outer surface 2b comes into elastic contact with the peripheral surface 3a as shown in FIG. 4 when the lip 2 is turned up while the seal 1 is being attached, the friction coefficient of the inner surface 2a with respect to the peripheral surface 3a is reduced. Since the coefficient is larger than the coefficient, the insertion force is significantly increased as compared with the normal state in which the lip 2 is not turned up. Therefore, it is easy to determine whether the lip is turned up, and the accuracy of the determination is also improved.

For example, in the embodiment of the invention according to the above-mentioned application specification, when a predetermined insertion force (expressed as “pull-out force” in the specification) exceeds a certain threshold value (predetermined value), it occurs. Although it is determined that the turned-up of the lip has not been corrected, the predetermined insertion force of the seal 1 according to the present invention is large, so that the threshold value can be easily set and the reliability of the determination result is high.

Further, since the frictional resistance between the outer surface 2b and the peripheral surface 3a is large, when the lip 2 is turned up, the tip 1c is moved by moving the seal 1 in the direction of arrow A with respect to the shaft 3. Outer surface 2b while being caught on peripheral surface 3a
Is peeled off from the peripheral surface 3a, and together with the elastic reaction force based on the deformation of the lip 2, the turn of the lip 2 is easily returned. Thereafter, for example, even if the lip 2 is moved in the direction opposite to the direction of the arrow A, the inner surface 2a elastically contacting the peripheral surface 3a
Has a small coefficient of friction, the lip 2 is less likely to be caught on the peripheral surface 3a and turned up again.

In the above, the surface roughness between the inner surface 2a and the outer surface 2b is made different so that the friction coefficient of the outer surface 2b with respect to the peripheral surface 3a is larger than that of the inner surface 2a. Even if not, the same effect can be obtained by applying a lubricant to the inner surface 2a.

Alternatively, instead of forming the outer surface of the lip 2 with the same member as the inner surface 2a, the inner surface 2a and the other lip 2
The outer surface 2d may be constituted by another member made of a material having a higher coefficient of friction than the elastic member constituting the main body (FIG. 5). Furthermore, the outer surface 2e having a surface rougher than the inner surface 2a may be formed by another member made of the same or different material as the elastic member forming the main body of the lip 2, and the friction coefficient of the outer surface with respect to the peripheral surface 3a may be increased ( (Fig. 6). The configurations shown in FIGS. 5 and 6 are particularly effective when the friction coefficients of the inner and outer surfaces of the lip cannot be made different by integral molding.

[0023]

Embodiment 2 In FIG. 7, reference numeral 6 denotes another example of the seal according to the present invention. The lip 7 of the seal 6 has an inner surface 7a elastically contacting the peripheral surface 3a of the shaft 3 in a normal state, and an inner surface 7a
And an outer surface 7b forming the front and back sides, and a lip 7
A rib elastically contacting the peripheral surface 3a in a folded state extends so as to cover the entire circumference in the circumferential direction. There may be a plurality of ribs or only one rib. In FIG. 7, two ribs, a small diameter rib 8 and a large diameter rib 9, are provided.

When the lip 7 is turned over, the seal 6 is in a state as shown in FIGS. 8 and 9, for example. In the former case, both the outer surface 7b and the ribs 8 and 9 are in elastic contact with the peripheral surface 3a, so that the frictional resistance between the shaft 3 and the lip 7 is larger than in the normal state where only the inner surface 7a is in elastic contact. Become. On the other hand, in the latter case, only the ribs 8 and 9 elastically contact the peripheral surface 3a and do not elastically contact the outer surface 7b, but the lip 7 is bent (warped) by an amount corresponding to the height and shape of the ribs 8 and 9. Increases, and the elastic reaction force of the lip 7 against the peripheral surface 3a increases,
The frictional resistance between the shaft 3 and the lip 7 is also increased.
Therefore, similarly to the first embodiment, it is easy to determine whether or not the lip is turned up, and the occurrence of the lip is easily returned.

FIG. 10 shows a seal 12 having ribs 10 and 11 in which the heights of the ribs 8 and 9 are not uniform, and FIG. 11 shows a seal 15 having ribs 13 and 14 formed by meandering the ribs 8 and 9. . According to the seal 12 or the seal 15, the contact area between the rib and the peripheral surface 3a is larger than that of the seal 6, so that the frictional resistance between the shaft 3 and the lip 7 can be more effectively increased. it can.

In FIG. 7, FIG. 10, and FIG.
a, 9a, 10a, 11a, 13a, and 14a indicate the tops of the ribs 8, 9, 10, 11, 13, and 14, respectively.

[0027]

As described above, according to the first aspect of the present invention, the friction coefficient of the inner surface with respect to the peripheral surface of the shaft is different from the friction coefficient of the outer surface. A clear difference occurs in the insertion force between when the lip is turned up and the lip can be easily determined.

According to the second or third aspect of the present invention, the friction coefficient of the outer surface with respect to the peripheral surface of the shaft is large, and the outer surface is less likely to slip with respect to the peripheral surface. When the lip is moved, the lip is caught on the peripheral surface and the curl can be easily returned.

According to the fourth aspect of the present invention, since the lubricant is applied to the inner surface, the friction coefficient of the outer surface with respect to the shaft peripheral surface is relatively higher than that of the inner surface even if the inner surface or the outer surface is not subjected to surface processing or the like. Thus, the effect of the invention of claim 2 or claim 3 can be enjoyed.

According to the fifth aspect of the present invention, since the outer surface is formed as a separate member from the inner surface, even in cases where it is difficult to integrally form the outer surface with the inner surface, the above-mentioned first to third aspects are described.
The effect of the invention can be enjoyed.

According to the sixth aspect of the present invention, since the rib which is in elastic contact with the peripheral surface of the shaft is formed on the outer surface when the lip is turned up, the friction between the shaft and the lip when the lip is turned up. The resistance can be increased, and the same effect as that of the second or third aspect can be obtained.

According to the seventh or eighth aspect of the present invention, the contact area between the rib and the peripheral surface of the shaft when the lip is turned up is increased, so that the frictional resistance between the shaft and the lip is increased accordingly. However, the effect of the invention of claim 6 can be further enjoyed.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a seal according to the present invention.

FIG. 2 is a perspective view showing a cross section of the seal of FIG.

FIG. 3 is an explanatory view showing a state of attachment (normal state) of the seal of FIG. 1 to a shaft.

FIG. 4 is an explanatory diagram showing a state where a lip is turned up.

FIG. 5 is a cross-sectional view showing a seal having an outer surface formed by another member made of a material having a higher coefficient of friction than an elastic member forming the inner surface.

FIG. 6 is a cross-sectional view showing a seal having an outer surface formed by another member having a larger surface roughness than the inner surface.

FIG. 7 shows a seal having ribs formed on the outer surface, and (a)
Is a front view, and (b) is a sectional side view.

FIG. 8 is an explanatory diagram showing an example of a state in which the lip of the seal of FIG. 7 is turned up.

FIG. 9 is an explanatory view showing another example of a state in which the lip of the seal in FIG. 7 is turned up.

FIG. 10 shows a seal having ribs of uneven height;
(A) is its front view, (b) is a sectional perspective view.

FIG. 11 shows a seal with meandering ribs, (a)
Is a front view, and (b) is a sectional perspective view.

[Explanation of symbols]

 Reference Signs List 1 seal 2 lip 2a inner surface 2b outer surface 3 shaft 3a peripheral surface

Claims (8)

[Claims] 1. A lip made of an elastic member, the lip having an inner surface which is in normal contact with a peripheral surface of a shaft and an outer surface which is in elastic contact with the lip when the lip is turned up, wherein the inner surface is provided with respect to the peripheral surface. Wherein the coefficient of friction of the outer surface and the coefficient of friction of the outer surface with respect to the peripheral surface are different. 2. The coefficient of friction of the outer surface with respect to the peripheral surface is:
The seal according to claim 1, wherein the coefficient of friction is greater than a coefficient of friction of the inner surface with respect to the peripheral surface. 3. The seal according to claim 2, wherein a surface roughness of the outer surface is larger than a surface roughness of the inner surface. 4. The seal according to claim 2, wherein a lubricant is applied to the inner surface. 5. The seal according to claim 1, wherein the outer surface is formed as a separate member from the inner surface. 6. A lip made of an elastic member, the lip having an inner surface elastically contacting a peripheral surface of a shaft in a normal state, and an outer surface forming front and back surfaces of the inner surface, wherein the lip is turned up on the outer surface. A seal, wherein a rib elastically contacting the peripheral surface is formed in a state. 7. The seal according to claim 6, wherein said rib extends along the circumferential direction so that its height is not uniform. 8. The seal according to claim 6, wherein said rib is formed so as to extend in a circumferential direction while meandering.