JPH07119841A - Oil seal - Google Patents

Abstract

PURPOSE:To enhance sealing performance by letting the amount of returned lubricant be deviced to be increased as much as possible by the pumping action of each rib. CONSTITUTION:Each rib 8 roughly in a triangle in cross section is provided for the circumferential oblique face 5A of the main seal lip 5 of an oil seal 2 on the side pressed against a rotating shaft 1 at several places where each rib is tilted against the axial line, and concurrently, fine irregularities 9 are provided for each area (each area enclosed by an imaginary line) roughly identical in length to each rib 8, in each portion by the side wall surface 8A for guiding returned lubricant for each rib 8, among the ribs 8 which are adjacent to one another in the circumferential direction. In this case, the fine irregularities 9 act as a lubricant basin. Besides, since the aforesaid irregularities 9 are positioned at an area which is subjected to the action of dynamic pressure by each rib 8, lubricant is thereby efficiently returned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil in which a ring-shaped metal core is provided with a seal lip made of an elastic body, and the seal lip is provided with an inclined surface which is partially brought into pressure contact with an outer peripheral surface of a rotary member. Regarding the seal.

[0002]

2. Description of the Related Art Some conventional oil seals are provided with ribs (so-called helix ribs) inclined with respect to the axis line at several circumferential positions on the slope of the seal lip. This rib is designed to return the leaked lubricating oil to the lubricating oil existing space side when the lubricating oil in the lubricating oil existing space leaks outward from the contact portion with the rotating shaft which is the contact partner of the oil seal. It acts, and is designed to generate a dynamic pressure from the outside toward the lubricating oil existing space side as the rotating shaft rotates. At this time, the lubricating oil is guided along one side wall surface of each rib. The action of returning the lubricating oil by such ribs is called a pump action.

[0003]

By the way, in the conventional oil seal, generally, the surface roughness of the entire inclined surface of the seal lip is set as small as, for example, 1 to 3 μm [Rz] so as to be as smooth as possible. However, in such a case, when the lubricating oil leaks, it is difficult to retain the lubricating oil on the slope of the seal lip, so the amount of lubricating oil returned by the rib pumping action cannot be increased. It can be said that the effect of preventing leakage is weak.

In view of such circumstances, it is an object of the present invention to enhance the sealability by increasing the amount of lubricating oil returned by the rib pumping action as much as possible.

[0005]

According to the present invention, an annular core metal is provided with a seal lip made of an elastic body, and the seal lip is provided with an inclined surface which is partially brought into pressure contact with the outer peripheral surface of the rotating member. The oil seal used has the following configuration.

In the oil seal of the present invention, ribs that are inclined with respect to the axis are provided at several circumferential positions on the inclined surface of the seal lip, and the lubrication of each rib is provided between adjacent ribs in the circumferential direction. Fine irregularities are provided on the side wall surface near the oil return guide.

[0007]

With the rotation of the rotary member, the rib of the seal lip generates a dynamic pressure from the outside toward the lubricating oil existing space. For this reason, when the lubricating oil in the lubricating oil present space leaks outward from the contact portion with the rotating member which is the contact partner of the oil seal, this lubricating oil is returned to the lubricating oil present space side by the dynamic pressure of the rib. Will be done. At this time, the lubricating oil is guided along one side wall surface of each rib.

When the lubricating oil leaks to the outside, the presence of fine irregularities serves as a resistance to the flow of the lubricating oil and is retained in the irregular portions, and the fine irregularities act on the dynamic pressure. Since it is located in the middle of the direction, the lubricating oil of this uneven portion can be efficiently returned to the lubricating oil existing space side.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to the embodiments shown in FIGS. FIG. 1 shows a first embodiment, in which 1 is a rotating shaft as a rotating member, and 2 is an oil seal. The oil seal 2 is composed of an annular core metal 3 whose upper half has a substantially L-shaped radial cross section, and an elastic body 4 such as rubber is attached to cover the inner and outer circumferences thereof. In this elastic body 4, an inner peripheral portion of the annular core metal 3 is provided adjacent to the main seal lip 5 and a triangular main seal lip 5 extending in one axial direction and sharpening toward the inner peripheral side. Is integrally formed with an auxiliary seal lip 6 extending obliquely in the opposite direction, and a garter spring 7 for pressing the auxiliary seal lip 6 against the outer peripheral surface of the rotary shaft 1 is attached to the outer periphery of the main seal lip 5. ing.

In the main seal lip 5, a portion of the circumference of an inclined surface (a surface located on the left side in the figure) 5A on the side that is partially brought into pressure contact with the rotary shaft 1 has a substantially triangular cross section at equal intervals. Ribs 8 are inclined with respect to the axis, and between the ribs 8 that are adjacent to each other in the circumferential direction, the ribs 8 are close to the side wall surface 8A for guiding the lubricating oil return of each rib 8 and are substantially the same as the ribs 8. Area of the same length (area surrounded by virtual lines)
The fine unevenness 9 is provided on the. This fine unevenness 9
The surface roughness is set to, for example, 5 to 10 μm [Rz], and can be formed by transfer from a mold, or can be formed by performing processing such as etching or shot processing. .

Next, the operation will be described. With the rotation of the rotary shaft 1, the rib 8 of the main seal lip 5 generates a dynamic pressure from the outside toward the lubricating oil existing space side. For this reason, when the lubricating oil in the lubricating oil existing space leaks outward from the contact portion with the rotary shaft 1, the 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.

When the lubricating oil leaks to the outside, the existence of the fine irregularities 9 serves as a resistance against the flow of the lubricating oil and is retained in the irregularities 9, and the fine irregularities 9 move. Since it is located in the middle of the direction in which the pressure acts, the lubricating oil present in this uneven portion 9 can be efficiently returned to the lubricating oil present space side. That is, the recovery rate of the lubricating oil by the pumping action of the ribs 8 becomes high. By the way, if the fine unevenness 9 is provided in the entire area between the ribs 8, a large amount of the leaked lubricating oil will be retained even in a portion unrelated to the dynamic pressure acting flow path. On the contrary, the recovery rate is lowered, which is not preferable.

The present invention is not limited to the above-mentioned embodiment, and the present invention includes those shown in FIGS. 2 and 3.
FIG. 2 shows a second embodiment, which is different from the first embodiment in the formation region of the fine irregularities 9. That is, the formation region of the unevenness 9 is the rib 8
Is specified in a triangular area as shown by an imaginary line in a length range of about half. Further, FIG. 3 shows the third embodiment, and the slope 5A of the main seal lip 5 is different from that of the first embodiment. That is, the slope 5A of the main seal lip 5 has a two-step shape, and the height of the rib 8 is set to gradually decrease toward the sharpened portion side of the main seal lip 5,
On the slope 5B of the first step on the sharpened portion side, fine irregularities 9 are formed in a triangular region shown by an imaginary line.

Further, as the ribs 8, the ribs of the above-mentioned embodiment and the ribs inclined in the opposite direction may be alternately provided. In this case, all of the ribs 8 are for guiding the lubricating oil of each rib 8. Fine irregularities 9 may be provided in the portion near the side wall surface. Then, the size and the formation area of the unevenness 9 can be appropriately changed.

[0015]

According to the present invention, in the oil seal configured to return the lubricating oil leaking to the outside, the leaking lubricating oil is held at a specific position on the slope of the seal lip to increase the returning amount of the lubricating oil. Since it is devised to do so, it is possible to increase the recovery rate of the lubricating oil that once leaked and to ensure high sealing performance.

[Brief description of drawings]

FIG. 1 is a perspective view of an upper half of a first embodiment of an oil seal of the present invention.

FIG. 2 is a perspective view of the upper half of the second embodiment of the oil seal of the present invention.

FIG. 3 is a perspective view of the upper half of the third embodiment of the oil seal of the present invention.

[Explanation of symbols]

 1 rotary shaft 2 oil seal 4 elastic body 5 main seal lip 5A slope of main seal lip 8 rib 8A side wall surface of rib 9 unevenness

Claims (1)

[Claims] 1. An oil seal, comprising: a ring-shaped cored bar provided with a seal lip made of an elastic body, and the seal lip provided with an inclined surface that is partially brought into pressure contact with an outer peripheral surface of a rotating member, Ribs that are inclined with respect to the axis are provided at several places on the circumference of the slope of the seal lip, and between the ribs that are adjacent in the circumferential direction, the ribs are near the side wall surface for lubricating oil return guide. An oil seal characterized by having fine irregularities.