JP2002340200A - Oil seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil seal capable of holding stable sealing performance over a long period. SOLUTION: A fluororesin for forming a seal surface 6 includes a fibered filler F. The lengthwise direction of the respective fibered fillers F is slantingly arranged in the shaft direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal in which at least a sealing surface of a seal lip is formed of a fluororesin.

[0002]

2. Description of the Related Art In general, as one of sealing devices for preventing leakage of a fluid, a rotary oil seal capable of preventing leakage of a sealing fluid in a bearing portion of a rotating shaft is known. As one type of such oil seals, there is known an oil seal in which at least the sealing surface of a seal lip is formed of a fluororesin having low friction, low wear, and excellent chemical resistance. This oil seal, whose sealing surface is made of fluororesin, is mainly used for sealing lubricating oil at high temperatures and high peripheral speeds for a long time, and requires low friction, low wear, and chemical resistance. It is used for applications.

[0003] As a fluororesin used for the sealing surface of the oil seal, a polytetrafluoroethylene (PTFE) resin having a low friction coefficient alone or a glass fiber or a carbon fiber is added to the PTFE resin so as to improve abrasion resistance. , Graphite, molybdenum, carbon, and the like, which are used alone or in combination of several kinds, are generally used in an appropriate amount as a filler.

In such an oil seal, it is known to provide a plurality of helical screws formed by protrusions or grooves for hydrodynamically assisting the sealing function at the tip of the lip of the sealing surface. . These screws have a pumping function that always positions a sealing fluid, such as lubricating oil, which is leaking from the sealing side toward the atmosphere side, on the sealing side, and exerts an additional sealing function. Such screws can be machined directly on the fluororesin before molding into the prescribed shape, or on the sealing surface of the seal lip of the fluororesin molded into the prescribed shape, or with a fluororesin sheet. When integrally molding rubber, a convex or concave portion corresponding to the screw is formed on the surface of the cavity of the mold opposite to the seal lip of the mold used for molding, and the seal lip is formed when the fluororesin sheet is plastically deformed. In general, it is formed by a method of transferring the convex portion or the concave portion to a portion to be a sealing surface.

[0005]

However, in the conventional oil seal with a screw, the sealing is performed by bringing the lip tip into contact with the rotating shaft with a predetermined tightening margin. As the rotation time increases, the screw provided at the tip of the lip becomes gradually smoother due to wear and settling of the sealing surface. There is a problem that the performance tends to decrease and stable sealing performance cannot be maintained for a long period of time.

[0006] The present invention has been made in view of these points, and an object of the present invention is to provide an oil seal that can maintain stable sealing performance for a long period of time.

[0007]

According to a first aspect of the present invention, there is provided an oil seal comprising a fibrous filler in which a fluororesin forming a sealing surface contains a fibrous filler. And the longitudinal direction of each fibrous filler is inclined with respect to the axial direction. And by adopting such a configuration,
It is possible to maintain stable sealing performance over a long period of time.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to embodiments shown in the drawings.

FIGS. 1 and 2 show a first embodiment of an oil seal according to the present invention. FIG. 1 is a cross-sectional view showing a main part of the entire structure, and FIG. 2 is a seal surface of a seal lip of FIG. FIG. 3 is a schematic diagram showing, in an expanded manner, the arrangement of fibrous fillers located near the tip of the lip of FIG.

The oil seal of the present embodiment is obtained by integrally molding a seal body formed of a rubber-like elastic body and a seal surface formed of a fluororesin.

As shown in FIG. 1, an oil seal 1 according to the present embodiment is formed so as to be mounted between a rotating shaft S and a housing H. This oil seal 1 has an annular reinforcing ring 2 formed in a substantially L-shaped cross section by metal or the like.
In addition, a seal body 3 formed of a rubber-like elastic body is formed by being integrally baked. An annular seal lip 4 is formed on the seal body 3 so as to gradually decrease in diameter from the inner peripheral portion of the reinforcing ring 2 toward the sealing side OS. A lip tip 5 abutting on the rotation axis S of the seal lip 4, and the rotation axis S
The sealing surface 6 having a predetermined sealing angle expanded toward the atmosphere side AS along the axis is defined by an annular resin sheet 7 made of a fluororesin containing at least a fibrous filler F to be described later. It is formed by baking together. That is, the sealing surface 6 of the sealing lip 4 is formed of fluororesin. In addition, the seal body 3
A garter spring 8 is mounted on the back side of the lip tip 5 of the garter.

The resin sheet 7 is, as shown in FIG.
The longitudinal direction of each fibrous filler F is inclined with respect to the axial direction shown in the vertical direction in FIG. These fibrous fillers F are dispersedly arranged in a state of being stacked along the thickness direction of the sealing surface 6, and are exaggerated by a solid line in FIG. Are located on the surface of the oil seal, and the depression formed by the trace of the fibrous filler F forms a groove M. It has the same pumping action as a screw.

The angle between the longitudinal direction of the fibrous filler F and the axial direction is 30-80 °, preferably 4 °.
It is good to be 5-70 degrees. Even if the angle exceeds this range,
If the angle falls below this range, the effect of the pump action will be impaired.

As shown in FIG. 2, the arrangement of the fibrous fillers F may be such that the fibrous fillers F adjacent to each other are positioned in parallel and at equal intervals. It is sufficient that the fibrous fillers F are arranged inclined with respect to the axial direction, and the directions and intervals of the fibrous fillers F may slightly vary.

As the fluororesin, modified tetrafluoroethylene (PTFE) having a low coefficient of friction or a polymerizable trace amount of a perfluoroalkyl vinyl ether monomer to improve the creep resistance is used.
Is generally used, and resins such as PFA, FEP, and ETFE are also used as needed.

As the fibrous filler F, carbon fiber, glass fiber, potassium titanate fiber, boron fiber,
Aramid fibers (aromatic amide fibers) and the like can be exemplified.

The resin sheet 7 for forming the sealing surface 6 in this embodiment has a wire diameter of 0.3 to 20 μm and a fiber length of 10 to 1000 with respect to 100 parts by weight of the PTFE resin.
A fiber containing 3 to 30 parts by weight of a μm fiber is used. As the resin sheet 7 in the present embodiment, PTF
Wire diameter 14 μm, fiber length 4 per 100 parts by weight of E resin
What contains 5 parts by weight of 00 μm carbon fiber is used.

The blending amount, wire diameter, fiber length, etc. of the fibrous filler F may be set as required according to the design concept and the like. Further, a plurality of types of fibers may be used in combination. Further, various compounding agents such as other fillers, coloring agents, and pigments can be added to the fluororesin according to the purpose of use, the purpose of design, and the like.

Next, the operation of the present embodiment having the above-described configuration will be described.

According to the oil seal 1 of the present embodiment, the fibrous filler F arranged obliquely with respect to the axial direction is arranged obliquely while being stacked in the thickness direction of the seal surface 6 and dispersed. In the initial state, the ridges formed by the fibrous filler F, which are exposed on the surface of the lip tip 5 of the sealing surface 6 in the initial state, and the concave grooves M formed by the traces of the fibrous filler F, It is possible to exert a pumping function of always positioning the sealed fluid that is to leak from the sealed side OS in the state toward the atmosphere side AS to the sealed side OS.

Further, according to the oil seal 1 of the present embodiment, the fibrous fillers F arranged obliquely with respect to the axial direction are arranged obliquely while being stacked in the thickness direction of the seal surface 6 and dispersed. Therefore, when the wear of the lip tip 5 of the sealing surface 6 progresses, the fibrous filler F located inside the sealing surface 6 in the initial state is sequentially exposed on the surface of the worn portion. A stable pump action can be exhibited.

This is because the sealing surface 6 in which the fibrous filler F is contained in the PTFE resin is a product of the present invention, and an oil seal formed of a PTFE resin having a helical thread formed by machining is conventionally used. When the performance of the conventional product and the product of the present invention having the same size is evaluated under the same conditions, the suction amount of the lubricating oil sucked from the atmosphere side AS to the sealing side OS, which represents the pumping action of the product of the present invention, is It was confirmed by the experimental result that the suction amount of the conventional product decreased with the passage of time, while the amount increased with the passage of time.

The reason why the pump action of the product of the present invention increases with time is that the fibrous filler F is dispersed in a state where the fibrous filler F is stacked and inclined in the thickness direction of the sealing surface 6. From this, it can be inferred that the cause is that the contact area with the rotating shaft S increases due to wear or settling of the lip tip 5 and at the same time the number of fibrous fillers F contacting the rotating shaft S increases.

Therefore, the oil seal 1 of the present embodiment
According to this, stable sealing performance can be reliably maintained over a long period of time.

FIG. 3 shows a second embodiment of the oil seal according to the present invention.
1 shows an embodiment. In the oil seal 1A of the present embodiment, the entire seal lip 4A is formed of fluororesin.

That is, the oil seal 1A of the present embodiment
Has a seal lip 4A formed in an annular shape,
An annular mounting portion 9 is formed on the seal lip 4A.
And a lip portion 10 formed such that the diameter gradually decreases from the inner edge of the mounting portion 9 toward the sealing side OS where the sealing fluid such as lubricating oil is located.

The mounting portion 9 of the seal lip 4A is formed of an elastic material such as rubber on the bottom surface of an outer ring 11 having a substantially L-shaped cross section formed of metal or the like fitted in the housing H in the mounted state. It is mounted via an annular gasket 12. A lower end surface of a reinforcing ring 2A having a substantially L-shaped cross section made of metal or the like mounted inside the outer ring 11 is in contact with an upper surface of the mounting portion 9 of the seal lip 4A. Then, the upper end of the mounting portion 11a to be fitted to the cylindrical housing H of the outer ring 11 is bent toward the center where the rotation axis S is located, so that the seal lip 4A, the outer ring 11, the gasket 12, and the reinforcing ring 2A can be integrated, and the reinforcing ring 2A is urged toward the bottom surface of the outer ring 11 so that the gasket 12 is attached to the mounting portion 9 of the seal lip 4A and the outer ring 11A.
The reinforcing ring 2A and the seal lip 4
It is formed so as to be able to prevent leakage of the sealed fluid that is leaking from A to the atmosphere side AS from the sealing side OS to A.

The lip portion 10 of the seal lip 4A has a lip tip 5A abutting on the rotation axis S, and a predetermined diameter expanded from the lip tip 5A along the rotation axis S toward the atmosphere side AS. A sealing surface 6A having a sealing angle is formed, and a desired area of the sealing surface 6A on the lip tip 5A side is brought into contact with the surface of the rotating shaft S in the mounted state. Further, the sealing surface 6A having a predetermined sealing angle, which is expanded in diameter from the lip tip 5A toward the atmosphere side AS along the rotation axis S, is inclined and arranged in the same manner as the sealing surface 6 of the first embodiment described above. It is formed of an annular resin sheet 7A made of a fluororesin containing the fibrous filler F.

That is, the oil seal 1A of the present embodiment
Is formed of a fluororesin containing a fibrous filler F in which the sealing surface 6A of the sealing lip 4A is inclined.

The other construction is the same as that of a conventionally known oil seal, and a detailed description thereof will be omitted.

According to the oil seal 1A of this embodiment having such a configuration, the same effects as those of the oil seal 1 of the above-described first embodiment can be obtained.

The present invention is not limited to the above embodiments, but can be variously modified as needed.

[0033]

As described above, according to the oil seal of the present invention, extremely excellent effects such as the ability to maintain stable sealing performance over a long period of time can be obtained.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a main part of an overall configuration of an oil seal according to a first embodiment of the present invention.

FIG. 2 is a developed view schematically showing an arrangement state of a fibrous filler located near a lip tip of a sealing surface of the seal lip of FIG. 1;

FIG. 3 is a view similar to FIG. 1, showing a main part of an overall configuration of an oil seal according to a second embodiment of the present invention;

[Explanation of symbols]

 1, 1A Oil seal 4, 4A Seal lip 5, 5A Lip tip 6, 6A Seal surface 7, 7A Resin sheet 9 Mounting part 10 Lip part F Fibrous filler M Groove H Housing S Rotating axis AS Atmospheric side OS Seal side

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Koji Ishii 3-30-1, Horikiri, Katsushika-ku, Tokyo F-term in Arai Seisakusho Co., Ltd. 3J006 AE04 AE14 CA04

Claims (1)

[Claims] 1. An oil seal wherein at least a sealing surface of a seal lip is formed of a fluororesin, wherein the fluororesin forming the sealing surface contains a fibrous filler, and each of the fibrous fillers An oil seal characterized in that a longitudinal direction is inclined with respect to an axial direction.