JPH10339373A - Oil seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To attain improvement of seal performance, by returning lubricating oil by pump action of a rib, so that a return amount of the lubricating oil can be increased as large as possible, in an oil seal. SOLUTION: In an oil seal 2, a seal lip 5 formed by an elastic unit 4 is provided in an annular core metal 3, in this seal lip 5, a slope 5A partly brought into press contact relating to a peripheral surface of a rotary member 1 is provided, in circumferential several parts of this slop 5A, a rib 8 tilted relating to an axial line is provided, and in a part in the vicinity of one side wall surface 8A for a lubricating return guide of each rib 8, at least a tip end edge side parts of the slope 5A is formed soft as compared without a seal lip main unit part. In this way, by easily deflecting the soft part, this part is easily floated from the rotary member 1 by a dynamic pressure generated by pump action of the lib 8, and lubricating oil returned by pump action is made to easily pass through the floated part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an annular cored bar provided with a seal lip made of an elastic material, and provided with a slope which is partially pressed against the outer peripheral surface of the rotating member. The present invention relates to an oil seal in which ribs inclined with respect to the axis are provided at several places around the circumference of the oil seal.

[0002]

2. Description of the Related Art Some conventional oil seals are provided with ribs (so-called helix ribs) that are inclined with respect to the axis at several places on the circumference of the slope of the seal lip.

[0003] In the case where the lubricating oil in the lubricating oil-existing space leaks outward from a portion in contact with the rotating shaft that is a contact partner of the oil seal, the rib transmits the leaked lubricating oil toward the lubricating oil-existing space. It is designed to generate a dynamic pressure from outside to the lubricating oil existing space side with the rotation of the rotating shaft. At this time, the lubricating oil is guided along one side wall surface of each rib. The lubricating oil returning action by such a rib is called a pump action.

[0004] In the conventional oil seal, generally, the entire elastic coefficient of the slope including the rib in the seal lip is substantially the same.

[0005]

Incidentally, even in the oil seal as described above, there is room for improvement since the return amount of the lubricating oil by the pump action of the rib is required to be as large as possible.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to improve the hermeticity of an oil seal so that the amount of lubricating oil returned by the pumping action of a rib can be increased as much as possible.

[0007]

According to the present invention, an annular core bar is provided with a seal lip made of an elastic material, and the seal lip is provided with a slope which is partially pressed against the outer peripheral surface of the rotating member. An oil seal in which ribs inclined with respect to the axis are provided at several places on the circumference of the slope is configured as follows.

[0008] In the first oil seal of the present invention, at least a tip edge portion of the inclined surface in the vicinity of one side wall surface for lubricating oil return guide in each of the ribs is softer than a seal lip body portion.

In the second oil seal of the present invention, the ribs are harder than the seal lip body.

In the third oil seal of the present invention, each rib is made harder than the seal lip main body by forming a thin film made of a fluorine-based synthetic resin on the surface of each rib.

[0011] In the fourth oil seal of the present invention, a thin film made of a fluorine-based synthetic resin is formed on the entire slope including the ribs, and a portion of the thin film covering the rib is compared with other portions. It is relatively hard.

In the fifth oil seal of the present invention, at least a tip end portion of the slope at a portion near one side wall surface for lubricating oil return guide in each of the ribs is softer than a seal lip body portion. Each of the ribs is harder than the seal lip body.

In general, an oil seal with ribs has
In the first place, the ribs generate a dynamic pressure from the outside toward the lubricating oil-existing space side with the rotation of the rotating member, so that the lubricating oil in the lubricating oil-existing space is moved outward from the contact portion with the rotating member, which is the contact partner of the oil seal. When it leaks to the lubricating oil, the lubricating oil functions to return to the lubricating oil existing space side by the dynamic pressure of the rib. At this time, the lubricating oil is guided along one side wall surface of each rib.

In order to increase the lubricating oil return amount at this time, in the present invention, the lubricating oil return passage is made easier, or the pump action by the ribs is enhanced.

That is, as in the first oil seal, if the portion near the one side wall surface is softer than the seal lip body portion, the soft portion is rotated by the dynamic pressure generated by the pump action. It becomes easy to float from the member. This lifting facilitates the passage of the lubricating oil returned by the above-described pump action.

Further, if the ribs are harder than the seal lip body portion as in the second, third, and fourth oil seals, the deformation of the ribs is reduced, and the pump action by the ribs is increased. Therefore, the portion of the rib near the one side wall surface for guiding the lubricating oil return on the inclined surface is easily lifted from the rotating member. In particular, if a thin film made of a fluorine-based synthetic resin having low frictional resistance and excellent wear resistance is formed like the third and fourth oil seals, it contributes to a reduction in rotational torque and a long life. become able to.

Further, in the fifth oil seal, since the first oil seal and the second to fourth oil seals are combined, the lubricating oil is returned more than the first to fourth oil seals. Is more effective.

[0018]

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

FIGS. 1 and 2 relate to a first embodiment of the present invention. FIG. 1 is a vertical sectional view of an upper half of an oil seal.
FIG. 4 is a developed plan view showing a main part of the oil seal after elapse of use. In the figure, reference numeral 1 denotes a rotating shaft as a rotating member, and 2 denotes an oil seal. The first embodiment corresponds to claim 1.

The oil seal 2 is composed of an annular core 3 whose upper half has a substantially L-shaped cross section in the radial direction, and an elastic body 4 such as rubber is attached so as to cover the inner and outer circumferences thereof. This elastic body 4
In the inner peripheral portion of the annular core bar 3, a triangular main seal lip 5 extending in one axial direction and being sharpened toward the inner peripheral side is provided adjacent to the main seal lip 5 and in a direction opposite to the main seal lip 5. An auxiliary seal lip 6 extending diagonally is provided, and an outer periphery of the main seal lip 5 is provided.
A garter spring 7 that presses the outer peripheral surface of the rotary shaft 1 against the outer peripheral surface is mounted.

The main seal lip 5 has several triangular cross-sections at regular intervals on the circumference of the inclined surface (the surface located on the left side in the figure) 5A on the side of the main seal lip 5 that is partially pressed against the rotating shaft 1. Are provided at an angle with respect to the axis, and between the ribs 8 adjacent in the circumferential direction, a portion near the one side wall surface 8A for lubricating oil return guide of each rib 8 (region surrounded by a virtual line). ) Is softer than the seal lip body. In order to form the soft portion, for example, the elastic body 4 itself is vulcanized and formed with soft rubber having a smaller elastic coefficient than that of a general oil seal, and irradiated with ultrasonic waves except for the region surrounded by the imaginary line. By doing so, the degree of crosslinking may be increased. The elastic modulus of the portion of the slope 5A other than the region surrounded by the imaginary line can be the same level as that of a general oil seal, for example.

The rib 8 is manufactured so as to have a uniform height along the entire length in the longitudinal direction. However, with the progress of use, as shown in FIG.
Is worn out, and the entire periphery of the tip end portion of the slope 5A including the rib 8 comes into contact with the rotary shaft 1 over substantially the entire surface (see the hatched portion).

Next, the operation will be described. With the rotation of the rotating shaft 1, the ribs 8 of the main seal lip 5 generate a dynamic pressure from the outside toward the lubricating oil existing space. For this reason, when the lubricating oil in the lubricating oil existing space leaks outward from the contact portion with the rotating shaft 1, this lubricating oil is returned to the lubricating oil existing space side by the dynamic pressure of the rib 8. At this time, the lubricating oil is guided along one side wall surface 8A of each rib 8.

Incidentally, in the main seal lip 5, the portion near the one side wall surface 8A for guiding the lubricating oil return of the rib 8 is set to be softer than the other portions. The lubricating oil returned by the above-described pumping action easily passes through a clearance formed by the pump shaft. Therefore, the once leaked lubricating oil is efficiently returned to the lubricating oil existing space side, and the recovery rate is improved.

Note that the present invention is not limited to only the first embodiment, and various applications and modifications are conceivable.

(1) In the first embodiment, the one side wall surface 8 of the main seal lip 5 for guiding the lubricating oil back of the rib 8
The area surrounded by the imaginary line in the vicinity of A is selectively softened, but the softened area is not particularly limited, and at least the tip end portion of the slope 5A is softer than the seal lip body. It should just be.

(2) FIG. 3 is a longitudinal sectional view of the upper half of the oil seal according to the second embodiment of the present invention. In the second embodiment, a thin film 9 made of a fluorine-based synthetic resin such as PTFE (polytetrafluoroethylene) is formed on the entire slope 5A of the main seal lip 5. The thin film 9 is formed by applying the solution by spraying or the like and then drying. And rib 8
By irradiating the thin film 9 on the surface portion with ultrasonic waves, the ribs 8 are made harder than other portions. The second embodiment corresponds to claim 4.

In such a configuration, since the thin film 9 is excellent in friction resistance and wear resistance, it is possible to contribute to the reduction of the rotational torque and the improvement of the life, and further to the lubrication as in the first embodiment. Oil return efficiency is also improved. That is, in the case of the second embodiment, although the main seal lip 5 is slightly harder than the first embodiment due to the thin film 9, the rib 8 is also hard, so that the rib 8 is in contact with the rotating shaft 1. 8 is less likely to be deformed and worn, and the pumping action of the ribs 8 is increased and the desired pumping action can be continued for a long period of time. The portion near the one side wall surface 8A of the rib 8 is easily lifted from the rotating shaft 1, and the lubricating oil is efficiently returned to the lubricating oil existing space side. It has been confirmed by the present inventors that as the pumping action increases, the amount of deformation of the main seal lip 5 also increases.

(3) Although not shown, in the second embodiment, the thin film 9 may be formed so as to cover only the surface portion of the rib 8 (corresponding to claim 3). In this case, the lubricating oil return efficiency is further improved as compared with the second embodiment.

(4) Although not shown, in Embodiment 2 described above, the thickness of the thin film 9 formed on the slope 5A in the vicinity of the one side wall surface 8A of each rib 8 is made thinner than in the other portions, so that it becomes soft. can do. An embodiment in which the first embodiment and the above (3) are combined, and (4)
An embodiment in which (3) and (3) are combined is also conceivable (corresponding to claim 5).

(5) In the oil seals 2 of the first and second embodiments, the ribs 8 having the same inclination are provided, but the ribs having the inclinations alternately reversed in the circumferential direction are provided. The present invention can also be applied to

[0032]

According to the first to fifth aspects of the present invention, in the oil seal configured to be able to return the lubricating oil leaking outward, the oil seal is devised so that the return passage for the leaking lubricating oil is easily formed. The lubricating oil returned by the pump action of the ribs can easily pass through the contact portion between the rotating member and the slope, so that the recovery rate of the once leaked lubricating oil can be increased, and high sealing performance can be secured. become.

In particular, according to the third and fourth aspects of the present invention, a thin film made of a fluorine-based synthetic resin having low frictional resistance and excellent wear resistance is formed on only the ribs or on the entire slope including the ribs. It is possible to contribute to the reduction of the rotation torque and the improvement of the service life.

Further, in the invention of claim 5, since the invention of claim 1 and the inventions of claims 2 to 4 are combined,
A better effect on lubricating oil return can be obtained than in the inventions of the first to fourth aspects.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an upper half of an oil seal according to a first embodiment of the present invention.

FIG. 2 is a developed plan view showing a main part of the oil seal according to the first embodiment after use progress.

FIG. 3 is a longitudinal sectional view of an upper half of an oil seal according to a second embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 rotating shaft 2 oil seal 5 main seal lip 5A slope of main seal lip 8 rib 8A one side wall of rib

Claims (5)

[Claims] 1. A seal lip made of an elastic material is provided on an annular core bar, and a slope which is partially pressed against an outer peripheral surface of a rotating member is provided on the seal lip. An oil seal provided with ribs inclined with respect to the axis, wherein at least a tip edge portion of the slope is softer than a seal lip body portion in a portion near one side wall surface for lubricating oil return guide in each rib. An oil seal, characterized in that: 2. An annular core metal is provided with a seal lip made of an elastic body, and the seal lip is provided with a slope which is partially pressed against the outer peripheral surface of the rotating member. An oil seal provided with ribs inclined with respect to an axis, wherein each rib is harder than a seal lip body. 3. An annular core metal is provided with a seal lip made of an elastic body, and the seal lip is provided with a slope which is partially pressed against the outer peripheral surface of the rotating member. An oil seal provided with ribs inclined with respect to the axis, wherein a thin film made of a fluorine-based synthetic resin is formed on the surface of each rib so that each rib is harder than the seal lip body. An oil seal, characterized in that: 4. An annular cored bar is provided with a seal lip made of an elastic body, and the seal lip is provided with a slope which is partially pressed against the outer peripheral surface of the rotating member. An oil seal provided with ribs inclined with respect to the axis, wherein a thin film made of a fluorine-based synthetic resin is formed on the entire slope including the ribs, and a portion of the thin film that covers the ribs. Characterized in that the oil seal is relatively harder than other parts. 5. An annular cored bar is provided with a seal lip made of an elastic body, and the seal lip is provided with a slope which is partially pressed against the outer peripheral surface of the rotating member, and is provided at several places on the circumference of the slope. An oil seal provided with ribs inclined with respect to the axis, wherein at least a tip edge portion of the slope is softer than a seal lip body portion in a portion near one side wall surface for lubricating oil return guide in each rib. An oil seal, wherein each of the ribs is harder than a seal lip body.