JP2000145975A - Oil seal - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil seal, wherein the leakage of hermetically sealed fluids through a screw groove is prevented even if a second seal lip is not provided in the hermetically sealed fluid side of a seal lip having the screw groove, and thus the second seal lip is omitted from the components of the oil seal. SOLUTION: In an oil seal 1 provided with a seal lip 14 fixed to one member 2 of two members 2 and 7 rotated in relative relation, and tightly connected to the other member 7 so as to freely slide and a screw groove 15 provided in the seal lip 14 to perform pumping for hermetically sealed fluids 11, at least one or more weirs 16 are provided in 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. An object of the present invention is to provide an oil seal which can eliminate the second seal lip or a part including the second seal lip from the components of the oil seal without the above.

[0011]

In order to achieve the above object, an oil seal according to the present invention is mounted on one of two relatively rotating members and is slidably in close contact with the other member. Wherein the seal lip is provided with a thread groove for pumping a sealing fluid, wherein at least one weir is provided in the thread groove.

When a thread groove is provided in the seal lip, the sealing fluid can be pushed back by the pumping action of the thread groove. When at least one weir is provided in the screw groove, the damping action of the weir plays. When the relative rotation is stopped, it is possible to prevent the sealed fluid from leaking along the thread groove. That is, the leakage of the sealing fluid such as oil along the thread groove is blocked by a weir provided in a part of the thread groove to seal.

[0013]

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

FIG. 1 is a half sectional view showing a state before mounting an oil seal 1 according to the present embodiment. FIG. 2 is a front view of the seal lip 14 provided with the thread groove 15 and is a view in the direction of arrow A in FIG.
1 is cut along the line BB in FIG. 2, and FIG. 1 is a state cut along the line CC. FIG. 4 is a partially enlarged view of FIG. FIG. 5 is a half cross-sectional view showing the mounted state of the oil seal 1, and FIG. 6 is an enlarged view of a main part thereof.

The oil seal 1 according to this embodiment is provided with a metal mounting ring 4 for mounting the oil seal 1 on the inner periphery of the shaft hole 3 of the housing 2 (see FIG. 5) of the device. A seal member (also referred to as a first seal member) 5 made of a rubber-like elastic material is vulcanized and bonded to the mounting ring 4. 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, and 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 at four locations evenly over the circumference of the screw groove 15.

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, a seal lip 14 having a thread groove 15 on an 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 axis 7
When the rotation of the screw is stopped, even if a part of the sealed 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 blocked by the weir 16 in the middle of the screw groove 15. Can be stopped. Therefore, when the rotation of the shaft 7 is stopped,
It is possible to prevent the sealing fluid 11 from leaking to the atmosphere side, and furthermore, it is the only sealing lip 1 provided with the thread groove 15.
4 seals the sealed fluid 11.

When the shaft 7 rotates with the operation of the device, pumping acts on the screw groove 15 and a force in the direction of the arrow x acts to push the sealed fluid 11 penetrating into the screw groove 15 to the inside of the machine (FIG. 9). 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. Also, when the shaft 7 rotates, a dynamic gap is generated between the weir 16 and the shaft 7 due to a phase difference in behavior due to 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, when the shaft 7 rotates,
The sealing fluid 11 can be sealed by a single sealing lip 14 provided with a 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.

Note that the oil seal 1 in the above embodiment is
Is suitable for use in construction machinery, civil engineering construction vehicles, automobile engines, and the like. In this case, the oil seal 1 seals oils, which are a type of viscous fluid. However, the shape or structure of the oil seal 1 in the above-described embodiment 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 screw groove 15 is triangular in the figure, it may be semicircular, rectangular, trapezoidal, or the like.

[0022]

The present invention has the following effects.

That is, in the oil seal of the present invention having the above-described configuration, at least one or more weirs are provided in the thread groove. Can be prevented from leaking along the thread groove, and even if the second sealing lip is not provided on the sealing fluid side of the sealing lip provided with the thread groove, the sealing fluid leaks along the thread groove. Can be prevented. 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.

[Brief description of the drawings]

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

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 sectional view of a main part showing a state where the oil seal is mounted.

FIG. 7 is a sectional view of an oil seal according to a conventional example.

[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 14c Outer peripheral end 15 Screw groove 16 Weir

Claims (1)

[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. An oil seal characterized by the provision of 6).