JP2001165328A - Oil seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil seal 1 that can display an excellent sealing performance and can prevent a sealing fluid 11 to leak out along a screw groove 15 unnecessarily forming a second seal lip at the side of the sealing fluid 11 of a seal lip 14 that is arranged at the screw groove 15 and capable of omitting the second seal lip from assembling parts of the oil seal 1 and consequently increasing a pressing force to another member 7 of the seal lip 14 in accordance with an increase of the pressure at the side of the sealing fluid 11. SOLUTION: The oil seal 1 consists of the seal lip 14 installed at a member 2 out of two relatively rotating members 2, 7, which freely slidably contacts the other member 7. The seal lip 14 has a screws groove 15 which performs pumping for the sealing fluid 11. In addition, an internal face of the screw groove 15 is formed to a tapered shape arranging a weir 16 at least one and more points at the screw groove 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil seal which is a kind of a sealing device.

[0002]

2. Description of the Related Art Conventionally, an oil seal 51 shown in FIG.
Is known, and is configured as follows.

[0003] First, a metal mounting ring 54 is provided for mounting the oil seal 51 on the inner periphery of the shaft hole 53 of the housing 52 of the device. The mounting ring 54 is provided with a rubber-like elastic material seal. The member 55 is vulcanized and bonded. The sealing member 55 is formed by a cylindrical portion 54a of the mounting ring 54.
And a seal lip 58 that seals between the mounting ring 54 and the housing 52 at the time of mounting, and a seal lip 58 that is slidably in close contact with the peripheral surface of the shaft 57 at the time of mounting. Outer peripheral seal part 56 and seal lip 5
8 are integrally formed via a connecting portion 59 provided inside the flange portion 54b of the mounting ring 54.

A second resin sealing member 60 is sandwiched between the flange portion 54b of the mounting ring 54 and the connecting portion 59 of the sealing member 55 in a non-adhesive manner. A seal lip 61 is provided on the peripheral surface of the shaft 57 so as to slide freely. The resin-made seal lip 61 is arranged on the inner peripheral side of the rubber seal lip 58 in the same direction, and is provided on the inner peripheral surface of the resin-made seal lip 61 with respect to the sealing fluid 62. And a screw groove 63 for performing a pumping action is provided. The screw groove 63 is provided at the tip 61 a of the resin seal lip 61.
Is formed as a single continuous groove from the bottom to the base end portion 61b.
Is extrapolated to the space 64 between the resin seal lip 61 and the rubber seal lip 58 through the screw groove 63.
And the space 65 on the atmosphere side are communicated with each other.

[0005] The oil seal 51 having the above structure is air-tightly fitted to the inner periphery of the shaft hole 53 of the housing 52,
7, the rubber seal lip 58 is
The sealing fluid 62 is sealed by contacting the peripheral surface of the sealing fluid 62 closely. Also, when the shaft 57 rotates, the rubber seal lip 58 is slidably in close contact with the peripheral surface of the shaft 57 to seal the sealing fluid 62. A part of the sealing fluid 62 is formed by the rubber sealing lip 58 and the shaft 57. And penetrates into the space 64 between the two seal lips 58 and 61 through the sliding portion of
3 may enter the shaft groove 57.
A pumping action is produced in accordance with the relative rotation of the sealing fluid 62 and the sealing fluid 62 is pushed back to the space 64 by the pumping action.

Accordingly, the oil seal 51 having the above-described structure is used.
According to this, it is possible to exert an excellent sealing effect by the pumping action of the thread groove 63, but this oil seal 51 still has the following disadvantages.

That is, as described above, one screw groove 63 provided on the inner peripheral surface of the resin seal lip 61 connects the space 64 between the seal lips 58 and 61 and the space 65 on the atmosphere side. Are formed as a continuous groove of the resin seal lip 6 provided with the thread groove 63.
If the rubber seal lip 58 is not provided on the side of the first sealing fluid 62, the sealing fluid 62 leaks to the atmosphere side along the screw groove 63 when the shaft 57 stops. Therefore, in the oil seal 51, the second seal lip 58 is always provided on the seal fluid 62 side of the seal lip 61 provided with the thread groove 63, and the seal fluid 62 is transmitted through the thread groove 63 by the second seal lip 58. To prevent leakage.

However, this second seal lip 5
8 is provided as a part of the rubber sealing member 55 as described above. This sealing member 55 is provided with a connecting portion 59 and an outer peripheral sealing portion 56 in addition to the sealing lip 58 and is relatively large. Molded as parts.

Therefore, in the oil seal 51, the large seal member 55 integrally including the seal lip 58, the connecting portion 59, and the outer peripheral seal portion 56 is an essential component. However, there is a disadvantage that the material cost is relatively high because a large amount of rubber material is required to form the large seal member 55.

[0010]

SUMMARY OF THE INVENTION In view of the above, the present invention has been made in view of the above circumstances, and a sealing fluid leaks along a thread groove without providing a second seal lip on the sealing fluid side of the seal lip provided with the thread groove. Therefore, it is possible to omit the second seal lip or a part including the second seal lip from the components of the oil seal, and to press the seal lip against the other member in response to the increase in the pressure on the sealed fluid side. It is an object of the present invention to provide an oil seal capable of increasing the sealing performance and thereby exhibiting excellent sealing performance.

[0011]

To achieve the above object, an oil seal according to claim 1 of the present invention is mounted on one of two relatively rotating members and slidably mounted on the other member. In an oil seal having a sealing lip that is in close contact with the sealing lip and having a thread groove for pumping a sealed fluid, at least one weir is provided in the thread groove, and the inner surface of the thread groove is inverted. It is characterized by being formed in a tapered shape.

According to a second aspect of the present invention, there is provided an oil seal according to the first aspect, wherein the inner surface of the thread groove located on the side of the sealed fluid with respect to the weir is formed in a reverse tapered shape. It is a feature.

When a thread groove is provided in the seal lip as in the oil seal according to the first aspect of the present invention having the above-described structure, the sealing fluid can be pushed back by the pumping action of the thread groove. By providing at least one or more weirs, it is possible to prevent the sealed fluid from leaking along the screw groove when the relative rotation is stopped by the weir action performed by the weirs. That is, the sealing fluid, such as oil, leaking along the thread groove is sealed by being blocked by a weir provided in a part of the thread groove.

In addition, in this oil seal, since the inner surface of the thread groove is formed in a reverse taper shape, the internal pressure in the screw groove acts on the inner surface of the reverse taper shape, and the seal lip is formed. Is generated against the other member, and the sealing lip is strongly pressed against the other member by this component force. Further, when the seal lip is strongly pressed against the other member, the weir is also strongly pressed against the other member, and these pressing forces increase as the pressure on the sealed fluid side increases. Therefore, it is possible to further improve the sealing performance of the oil seal by forming the inner surface of the thread groove in a reverse tapered shape in this manner,
For example, when the air sealing property under high pressure is insufficient,
This can be compensated for.

[0015] The technical contents of the air sealing property are as follows.

That is, in a general oil seal in which a thread groove is provided in a seal lip, if the pressure on the sealed fluid side rises while the seal lip is in contact with the other member, air leaks as shown in the graph of FIG. In some cases, an increase in the amount may be observed.At this time, when checking the contact state of the seal lip with the other member, air may leak directly in the thrust direction instead of along the thread groove. In order to prevent the air leakage in the thrust direction, it is necessary to increase the close contact force of the seal lip with the other member. Therefore, as in the case of the oil seal according to the first aspect of the present invention, when the inner surface of the thread groove is formed in an inversely tapered shape to increase the close contact force of the seal lip with the other member, the air leakage in the thrust direction is effectively performed. Can be prevented. Since the reverse tapered shape is arranged so as to be close to the sealed fluid and against the air leakage path, as described in claim 2, the thread groove located on the sealed fluid side from the weir should be the inner surface on the atmosphere side. Is preferred.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an oil seal 1 according to this embodiment.
FIG. 3 is a half-section view showing a state before mounting. FIG. 2 is a front view of the seal lip 14 provided with the thread groove 15, and FIG.
FIG. 1 is a view taken in the direction of arrow A, and FIG. 1 illustrates a state in which the seal lip 14 is cut along the line BB in FIG.
FIG. 3 shows a state cut along the line CC. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a half cutaway view showing the mounted state of the oil seal 1, and FIG. 6 and FIG. FIG. 8 is a sectional view taken along line DD in FIG.

The oil seal 1 according to this embodiment is
The oil seal 1 is attached to the housing 2 of the device (see FIG. 5).
A metal-made mounting ring 4 for mounting on the inner periphery of the shaft hole 3 is provided. A sealing member (also referred to as a first sealing member) 5 made of a rubber-like elastic material is vulcanized and bonded to the mounting ring 4. I have. The seal member 5 is attached to the outer peripheral surface and the axial end surface of the cylindrical portion 4a of the mounting ring 4 and seals between the mounting ring 4 and the housing 2 at the time of mounting.
And a seal lip 8 slidably in contact with the peripheral surface of the shaft 7 (see FIG. 5) at the time of mounting, and the outer peripheral seal portion 6 and the seal lip 8 are formed on the flange portion 4 b of the mounting ring 4. It is integrally formed via a connecting portion 9 attached to the outer end surface. However, this seal lip 8 is different from the rubber seal lip 58 in the above-mentioned prior art in that the sealing fluid 11 (see FIG.
This is a dust seal for preventing foreign matter such as dust from entering the side of the mounting ring 4, and is disposed on the inner peripheral side of the flange portion 4b of the mounting ring 4 and has a resin seal lip 14 described later.
Means to face the opposite side in the axial direction at the time of mounting.

A second sealing member 12 made of resin is provided on the inner peripheral side of the cylindrical portion 4a of the mounting ring 4 and inside the flange portion 4b. The second seal member 12 is formed in a flat plate shape and a serpentine shape using a predetermined resin such as a tetrafluoroethylene resin (PTFE) as a molding material, and a base end portion 12a near an outer periphery thereof is attached to a mounting ring. The fitting ring 4 is fitted to the inner peripheral side of the cylindrical portion 4a of the fixing member 4 with a predetermined interference.
Fixed against. Between the base end portion 12a and the flange portion 4b of the mounting ring 4, an inner seal portion 13 integrally formed with the first seal member 5 and attached to the inner end surface of the flange portion 4b is provided. The inner seal 13 seals the space between the second seal member 12 and the mounting ring 4. The means for fixing the second seal member 12 to the mounting ring 4 may be, for example, an adhesive instead of fitting. The fixing means is not particularly limited, and a dedicated fixing member (not shown) is used. Is also good.

A portion near the inner periphery of the second seal member 12 is formed as a seal lip 14. A thread groove (pump) for pumping the sealing fluid 11 is formed on the outer end surface 14a of the seal lip 14 in a free state. (Also referred to as a thread groove portion) 15. As shown in FIG. 2, the thread groove 15 is formed as a single continuous spiral groove extending from the inner peripheral end 14 b to the outer peripheral end 14 c of the seal lip 14. No groove is formed in the middle, so that the screw is cut off in the middle of the shape or structure (also referred to as a seal dam portion) 1
The required number 6 is provided. In the drawing, the weirs 16 are provided in four equally spaced positions over one round of the screw groove 15.
Each weir 16 is formed flush with the outer end surface 14 a of the seal lip 14. The thread groove 15 is provided with a weir 16
The outer diameter side (atmosphere side at the time of mounting) is formed in a triangular cross section, while the inner diameter side (sealing fluid side at the time of mounting) than the weir 16 is sealed fluid as shown in FIG. The inner surface 1a is formed in a rectangular cross section having a side inner surface 15a, a bottom surface 15b, and an atmosphere side inner surface 15c.
5a is formed at right angles to the outer end surface 14a, while the atmosphere-side inner surface 15c is formed in an inverse tapered shape having a predetermined angle (obtuse angle) θ (90 ° <θ <180 °) with respect to the outer end surface 14a. Is formed. Therefore, in this portion, the screw groove 15 is a kind of dovetail groove.

As shown in FIGS. 5 and 6, when the oil seal 1 is fitted on the inner periphery of the shaft hole 3 of the housing 2, the seal lip 14 having a thread groove 15 on the outer end surface 14a is provided. Is extrapolated to the shaft 7 and is spread in a trumpet shape by the shaft 7. The inner peripheral end 14b of the seal lip 14 faces the inside of the machine, that is, the side of the sealing fluid 11, so that the outer end surface 14a is the inner peripheral surface and is in close contact with the peripheral surface of the shaft 7. Since the thread groove 15 is provided from the inner peripheral end 14 b to the outer peripheral end 14 c of the seal lip 14, the sealing fluid 11 is sealed through the thread groove 15 unless the weir 16 is provided in the middle. The interior space and the atmosphere-side space 10 are communicated with each other. However, since the weir 16 is provided, the communication is interrupted on the way. Therefore, when the rotation of the shaft 7 is stopped, even if a part of the sealing fluid 11 flows to the atmosphere side through the screw groove 15 in a state where the pumping of the screw groove 15 is not acting, this flow is not removed by the weir 16.
Is intercepted on the way. Therefore, when the rotation of the shaft 7 is stopped, the sealed fluid 11 can be prevented from leaking to the atmosphere side, and the sealed fluid 11 can be sealed by the only seal lip 14 provided with the thread groove 15.

When the shaft 7 rotates with the operation of the apparatus, pumping acts on the thread groove 15 and a force in the direction of arrow x acts to push the sealed fluid 11 penetrating into the thread groove 15 to the inside of the machine (FIG. 1). 6). Therefore, the sealing fluid 11 is pushed back to the inside of the machine by the pumping action of the thread groove 15, thereby preventing the sealing fluid 11 from leaking to the atmosphere side. When the shaft 7 rotates, a dynamic gap is generated between the weir 16 and the shaft 7 due to a phase difference between the eccentricity of the shaft 7 and the eccentricity of the seal lip 14. The operation is almost the same as the conventional one without the weir 16. Therefore, even when the shaft 7 rotates, the sealing fluid 11 can be sealed by the only seal lip 14 provided with the thread groove 15.

As described above, according to the oil seal 1, regardless of whether the shaft 7 is stopped or rotated, the sealing fluid 11 can be sufficiently sealed by the single seal lip 14 provided with the thread groove 15. It is. Therefore, thread groove 1
Even if the second sealing lip is not provided on the sealing fluid 11 side of the sealing lip 14 having the
, It is possible to omit the second seal lip or a part including the second seal lip from the components of the oil seal 1. Therefore, the oil seal 1 can be reduced in weight by providing the second seal lip or a part including the second seal lip, and a product advantageous in terms of material cost can be provided.

In addition, in the oil seal 1 according to the present embodiment, the atmosphere-side inner surface 15c of the screw groove 15 located on the inner diameter side (the sealed fluid 11 side at the time of mounting) with respect to the weir 16 has an inverted tapered shape. As shown in FIG. 7, the internal pressure p in the thread groove 15 acts on the reverse tapered inner surface 15c to generate a component force for pressing the seal lip 14 against the shaft 7, as shown in FIG. This component force causes the seal lip 14 to be strongly pressed against the peripheral surface of the shaft 7. When the seal lip 13 is strongly pressed against the peripheral surface of the shaft 7, the weir 16 is also strongly pressed against the peripheral surface of the shaft 7,
These pressing forces increase as the pressure on the sealed fluid 11 increases. Therefore, by forming the inner surface 15c of the thread groove 15 in a reverse tapered shape, it is possible to further improve the sealing performance of the oil seal, and to improve the air sealing performance under high pressure as described above. Can be. As shown in FIG. 8, even if the end face 16 a (particularly, the end face on the sealed fluid side) of the weir 16 located in the thread groove 15 is formed in a reverse taper shape, the weir 16 is still strongly attached to the peripheral surface of the shaft 7. There is an effect that it can be pressed (the end surface 16a of the weir 16 is also a part of the inner surface of the screw groove 15).

Further, the oil seal 1 according to this embodiment
The shape or structure of the lip seal is merely an example, and the technical scope of the present invention includes various types of lip seals having the thread groove 15. The seal lip 14 may be expanded in a trumpet shape before mounting, and the material thereof may be rubber or the like other than resin. Further, although the sectional shape of the thread groove 15 on the outer diameter side with respect to the weir 16 is triangular in the figure, it may be semicircular, rectangular, trapezoidal, or the like.

[0027]

The present invention has the following effects.

That is, in the oil seal according to the first aspect of the present invention having the above-described structure, since at least one or more weirs are provided in the thread groove, the relative rotation is performed by the damming action of the weir. It is possible to prevent the sealing fluid from leaking along the thread groove at the time of stopping, and even if the sealing fluid is not provided with the second sealing lip on the sealing fluid side of the sealing lip provided with the thread groove, the sealing fluid can be screwed. It is possible to prevent leakage along the groove. Therefore, the second seal lip or a part including the second seal lip can be omitted from the components of the oil seal, whereby the weight of the product can be reduced and the material cost can be reduced.

Further, since the inner surface of the thread groove is formed in a reverse taper shape, the inner surface of the thread groove is increased in accordance with an increase in pressure on the sealed fluid side.
The pressing force on the other member of the seal lip and the pressing force on the other member of the weir can be increased,
Thereby, the sealing performance with respect to the air sealing property and the like under high pressure can be further improved.

In addition to the above, in the oil seal according to the second aspect of the present invention having the above-described structure, the thread groove of the sealing fluid side closer to the sealing fluid than the weir which is arranged to be opposed to the air leakage path. Since the atmosphere side inner surface is formed in a reverse taper shape, air leakage can be more effectively prevented.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a state before an oil seal according to an embodiment of the present invention is mounted.

FIG. 2 is a front view of a seal lip in the oil seal.

FIG. 3 is a half cut sectional view of the oil seal cut along the line CC in FIG. 2;

FIG. 4 is a partially enlarged view of FIG. 2;

FIG. 5 is a half cut sectional view showing an attached state of the oil seal.

FIG. 6 is an enlarged view of a main part of FIG. 5;

FIG. 7 is an enlarged view of a main part of FIG. 5;

8 is a sectional view taken along line DD in FIG.

FIG. 9 is a sectional view of an oil seal according to a conventional example.

FIG. 10 is a graph showing the relationship between the sealing fluid pressure and the amount of air leakage.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oil seal 2 Housing (one member) 3 Shaft hole 4 Mounting ring 4a Cylindrical part 4b Flange part 5 Seal member 6 Outer peripheral seal part 7 Shaft (the other member) 8 Seal lip (dust lip) 9 Connecting part 10 Atmospheric space DESCRIPTION OF SYMBOLS 11 Sealed fluid 12 Second seal member 12a Base end 13 Inner seal part 14 Seal lip 14a Outer end face 14b Inner peripheral end part 14c Outer peripheral end part 15 Screw groove 15a Sealed fluid side inner surface 15b Bottom surface 15c Atmospheric side inner surface 16 Weir 16a End surface

Claims (2)

[Claims] 1. A seal lip (14) mounted on one member (2) of two relatively rotating members (2) and (7) and slidably in contact with the other member (7), An oil seal (1) in which the sealing lip (14) is provided with a thread groove (15) for pumping a sealing fluid (11).
In the above-mentioned screw groove (15), at least one or more weirs (1)
6) and the inner surface (1) of the thread groove (15).
5c) is formed in a reverse tapered shape. 2. The oil seal according to claim 1, wherein an inner surface (15c) of the screw groove (15) located on the side of the sealing fluid (11) from the weir (16) is formed in a reverse tapered shape. Oil seal.