JPH0755014A - Oil seal - Google Patents

Abstract

PURPOSE:To provide an oil seal by which the leakage of lubricating oil can be always prevented by exerting a force for turning the lubricating oil toward the one side in the axial direction whether the rotating direction of a turning shaft is in the normal direction or in the reverse direction. CONSTITUTION:An oil seal is so contrived that lubricating oil is retained on the one side in the axial direction of the tapering end part 2 of a seal lip 1 being pressedly in contact with a turning shaft 6, and a plurality of long narrow circular recessed parts 10 being parallel to the axial direction of the turning shaft 6 are formed on the sloped surface 2a on the atmospheric side excepting the edge 3 of the end part 2. Thereby, when the turning shaft 6 rotates, the recessed parts 10 receive a larger force in the rotating direction and incline as they are near to the edge 3 of the end part 2. The direction of the inclination of the recessed parts 10 alternates in accordance with the rotational direction of the turning shaft 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal for sealing lubricating oil of a rotary shaft.

[0002]

2. Description of the Related Art Conventionally, as this type of oil seal,
As shown in FIG. 3, there are some which have a seal lip 31 made of an elastic member such as rubber and in which a minute unevenness 32 is formed on the sliding contact surface of the seal lip 31 which is in sliding contact with the rotating shaft 33. This oil seal is formed by the oil collecting effect of the unevenness 32 formed on the sliding contact surface of the seal lip 31,
The lubricating oil 35 is easily retained between the seal lip 31 and the rotary shaft 33, and the oil film is easily secured. Further, the unevenness 32 also has a labyrinth effect, and the labyrinth effect and the oil sump effect cause the lubricating oil 3 on one side (the right side in FIG. 3) in the axial direction of the seal lip 31 to be inside.
5 is prevented from leaking to the atmosphere side 36.

However, this oil seal has a small force for forcibly pumping the lubricating oil between the sliding contact surface of the seal lip 31 and the rotary shaft 33 inward. That is, this oil seal has a small pumping action on the lubricating oil. Therefore, there is a problem that the lubricating oil is apt to leak.

Therefore, when the rotating shaft rotates, a force is exerted on the lubricating oil between the sliding contact surface of the seal lip and the rotating shaft toward the lubricating oil side to positively prevent the lubricating oil from leaking. In order to prevent this, an oil seal is known in which a plurality of oblique grooves in one direction are formed or a plurality of C-shaped grooves are formed on the inclined surface of the seal lip on the atmosphere side (for example, the actual open shaft). No. 62-93463).

[0005]

However, in the above-mentioned oil seal having a plurality of diagonal grooves formed in one direction, when the rotating shaft rotates in the reverse direction, a force is exerted to direct the lubricating oil toward the atmosphere side, so that the hermetic sealing is performed. There is a problem that performance is impaired. Further, in the oil seal having the above-mentioned plurality of C-shaped grooves, the above-mentioned problem of the oil seal having the above-mentioned diagonal groove in one direction is solved in that it can cope with the rotation shaft rotating in both directions. Since a pair of grooves that are inclined in opposite directions with respect to the center are formed, the number of grooves that can be formed on the inclined surface of the seal lip is smaller than when only one direction of oblique groove is formed, and the pump amount is increased. There is a problem that is reduced. Also, in the case of an oblique groove in one direction, it is possible to roll-form an empty part that forms this groove in the mold for manufacturing the seal lip by knurling, but in the case of multiple C-shaped grooves, knurling Since it is difficult to form this in the mold with high accuracy using, it is necessary to form the above-mentioned void by an embossing method or an electric discharge machining, which is inferior to the knurling in terms of accuracy. There is a problem that it is difficult to manufacture in terms of accuracy.

Therefore, an object of the present invention is to make it easily,
Whether the rotation direction of the rotating shaft is forward or reverse, a force can be applied that causes the lubricating oil that leaks from the lubricating oil side to the atmosphere side to be directed toward the sealed lubricating oil side. To provide an oil seal that can always prevent the leakage of lubricating oil.

[0007]

In order to achieve the above object, the oil seal of the present invention is slidably in contact with the outer peripheral surface of the rotating shaft, and has a lubricating oil side inclined surface and an atmosphere side inclined surface. An oil seal having a seal lip is characterized in that a large number of elongated concave portions or convex portions substantially parallel to the axis of the rotary shaft are formed on the inclined surface on the atmosphere side excluding the leading edge of the seal lip.

[0008]

In the oil seal, the tapered tip end of the seal lip having the inclined surface on the lubricating oil side and the inclined surface on the atmosphere side is pressed against the rotary shaft. Therefore, the pressure that the tip receives from the rotary shaft decreases from the position of the edge of the tip toward both sides in the axial direction. That is, the pressure distribution at this time is as shown in FIG. When the rotary shaft rotates in this state, the concave portion or the convex portion formed on the inclined surface on the atmosphere side receives a larger force in the direction of the rotation as it approaches the edge of the tip portion, and the rotation is increased. The distance that can be moved in the direction of increases. Therefore, the concave portion or the convex portion is tilted, for example, as shown in FIG. Moreover, when the rotation direction of the rotary shaft is reversed, the inclination of the concave portion or the convex portion is reversed.

That is, the concave portion or the convex portion is tilted in the opposite direction when the rotation direction of the rotary shaft is reversed, and regardless of whether the rotation direction of the rotary shaft is the normal direction or the reverse direction, the lubricant oil side is changed to the atmosphere side. The lubricating oil that is about to leak is moved toward the sealed lubricating oil side by the pumping action along the inclined concave portion or convex portion.

Therefore, according to the present invention, regardless of whether the rotating shaft rotates in the forward direction or in the reverse direction, a force is exerted to cause the lubricating oil that is about to leak toward the sealed lubricating oil side. It is possible to prevent leakage of lubricating oil at all times.

[0011]

The present invention will be described in detail below with reference to the embodiments shown in the drawings.

FIG. 1A shows a partial cross section of a seal lip 1 of an embodiment of the oil seal of the present invention. This oil seal seals the lubricating oil 5 on one side in the axial direction of the seal lip 1, that is, on the inner side (right side in FIG. 1A).

The seal lip 1 has an annular shape as a whole and has a hole 7 into which the rotary shaft 6 shown in FIG. 2 (A) is inserted. Further, the seal lip 1 has a tip portion 2 which is in sliding contact with the rotary shaft 6.

The tip portion 2 has an inclined surface 2b on the side of the lubricating oil 5 and an inclined surface 2a on the side of the atmosphere 11 and is pressed inward in the radial direction by a garter spring 8 mounted on the outer peripheral side. It is adapted to be pressed against the rotary shaft 6. As shown in FIG. 2 (A), the pressure acting on the tip portion 2 is the largest at the position of the edge 3 of the tip portion 2,
It decreases from the edge 3 toward both sides in the axial direction.

A large number of oval recesses 10 are formed in the axial direction on the inclined surface 2a on the other side in the axial direction than the end edge 3 of the tip portion 2, that is, on the left side in FIG. Has been done.
The recess 10 has a depth of about 10 μm, is substantially parallel to the axial direction of the rotary shaft 6, and has a dimension A in the axial direction.
It is set to about 20 to 50 μm, and the circumferential dimension B is about 5 to 5 μm.
It is set to 10 μm. Further, the recess 10 is formed on the atmosphere-side inclined surface 2a excluding the edge 3 of the tip 2. Further, the recesses 10 are arranged in a plurality of rows in the axial direction, and the recesses 10 in each row are formed at the same position in the circumferential direction.

In this embodiment, the lubricating oil filled in one axial side of the seal lip 1, that is, the right side in FIG. 5 does not leak out between the rotary shaft 6 and the tip 2 of the seal lip 1.

Further, the presence of the recess 10 facilitates holding of the lubricating oil 5 between the tip 2 and the rotary shaft 6, and holds an oil film between the tip 2 and the rotary shaft 6. It will be easier. Therefore, the lubricating oil sealing performance can be improved.

In addition, in this embodiment, the rotary shaft 6 is shown in FIG.
When rotated in the direction shown in (B), the concave portion 10 receives a larger force that is moved in the rotational direction as it approaches the edge 3 of the tip 2. Therefore, the recess 10 formed in the inclined surface 2a on the atmosphere side of the tip portion 2 is inclined as shown in FIGS. 1 (B) and 2 (B). Therefore, at this time, the lubricating oil which is about to leak to the side of the inclined surface 2a receives a force directed toward the edge 3 of the tip 2 along the recess 10.
That is, the lubricating oil receives a force toward the sealed lubricating oil side, that is, the right side in FIG. 2 (A).

On the other hand, when the rotary shaft 6 rotates in the direction opposite to that shown in FIG. 1B, the recess 10 tilts in the opposite direction to that shown in FIG. 1B. Therefore, at this time, the lubricating oil that is about to leak to the inclined surface 2a side is the same as when the rotating shaft 6 rotates in the forward direction, and the lubricating oil side that is sealed along the concave portion 10 that is inclined in the opposite direction. Receive the force toward.

As described above, according to this embodiment, the tip 2 of the seal lip 1 and the rotary shaft 6 are rotated regardless of whether the rotary shaft 6 rotates in the forward direction or in the reverse direction. It is possible to apply a force directed to the lubricating oil 5 side, which is sealed to the lubricating oil between 6 and 6.

Therefore, according to this embodiment, the inclination direction of the recess 10 of the seal lip 1 changes according to the rotation direction of the rotary shaft 6, and the rotation direction of the rotary shaft 6 is always forward or reverse. It is possible to prevent leakage of lubricating oil. Moreover, the recess 10 has a larger pumping action than the conventional C-shaped groove and can be easily manufactured.

In the above embodiment, the recess 10 has an oval shape, but it goes without saying that it may have a rectangular shape.
Further, instead of the concave portion 10, a convex portion may be used.

[0023]

As is apparent from the above, according to the oil seal of the present invention, an elongated concave portion or a convex portion parallel to the rotating shaft is formed on the atmosphere-side inclined surface excluding the tip edge of the seal lip that is pressed against the rotating shaft. Part is formed.

Therefore, according to the present invention, when the rotary shaft rotates, the concave portion or the convex portion formed on the atmosphere-side inclined surface of the seal lip is rotated closer to the edge of the tip portion. By receiving a large force in the direction of, the distance moved in the direction of rotation becomes large. Therefore, according to the present invention, whether the rotation direction of the rotating shaft is the forward direction or the reverse direction, the inclination direction of the concave portion or the convex portion is changed according to the rotating direction of the rotating shaft, It is possible to exert a force that directs the lubricating oil that is about to leak toward the sealed lubricating oil side.

That is, according to the present invention, the leakage of the lubricating oil can always be positively prevented regardless of whether the rotating shaft rotates in the forward or reverse direction.

[Brief description of drawings]

FIG. 1 (A) is a partial sectional view of an embodiment of an oil seal of the present invention when the rotating shaft is stationary, and FIG. 1 (B) is a partial sectional view of the above embodiment when the rotating shaft is rotating. .

FIG. 2 is a diagram showing a pressure distribution of a seal lip which is brought into pressure contact with a rotating shaft in the embodiment.

FIG. 3 is a partial cross-sectional view of a conventional oil seal.

[Explanation of symbols]

1 ... Seal lip, 2 ... Tip part, 2a ... Surface, 3 ... Edge,
5 ... Lubricating oil, 6 ... Rotating shaft, 7 ... Hole, 8 ... Tightening ring, 1
0 ... concave part.

Claims (1)

[Claims] 1. An oil seal having a seal lip that is in sliding contact with the outer peripheral surface of a rotating shaft and has a lubricant-side inclined surface and an atmosphere-side inclined surface, the inclination of the atmosphere side excluding the tip edge of the seal lip. An oil seal, characterized in that a large number of elongated concave portions or convex portions substantially parallel to the axis of the rotating shaft are formed on the surface.