JP2005016627A - Sealing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sealing device 1 composed of a seal body 2 fixed to a housing, a first seal lip 4 formed rigidly on the body 2 and contacting a rotary shaft 3 slidably, and a second seal lip 5 formed on the side with a fluid to be sealed of the first seal lip 4 and contacting the rotary shaft 3 slidably, capable of forming the seal with lower torque while requisite sealing performance is secured. <P>SOLUTION: The sealing device is structured so that a fluid leak is precluded by allowing the second seal lip 5 to contact with the rotary shaft 3 over the whole peripheral circumference when the shaft is at a standstill, while fluid leak is prevented when the shaft is rotating, by allowing the seal lip 4 to work the pumping motion with the aid of a threaded portion 10 formed in its slide part, and the seal action is generated differently by the first 4 and the second seal lip 5 between the shaft is at a standstill and is rotating. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a sealing device, and more particularly to a sealing device having a plurality of lip structures in which a second seal lip is provided on a fluid to be sealed side of a first seal lip slidably contacting a rotating shaft. is there. The sealing device of the present invention is used, for example, as a seal part in an automobile-related field, or as a seal part of other general industrial equipment.
[0002]
[Prior art]
Conventionally, as shown in FIG. 4, a sealing lip 53 slidably contacting the peripheral surface of the rotating shaft 52 is provided, and a sealing portion provided with a screw portion 54 that performs a pumping action on the sliding portion of the sealing lip 53. A device 51 is known, and in this sealing device 51, one seal lip 53 has both a sealing capability when the shaft is stationary by applying interference to the rotating shaft 52 and a pumping capability when rotating the shaft by applying screws. It is assumed to be a responsible structure.
[0003]
However, in recent years, for example, in the field of automobiles, a reduction in the torque of the seal has been demanded for the purpose of improving fuel efficiency. Therefore, there is a limit to the reduction in torque by a technique such as a lip cross section.
[0004]
Further, as shown in FIG. 5, the applicant of the present application previously has a seal body 62 fixed to the housing, and a first seal lip that is provided integrally with the seal body 62 and slidably contacts the rotating shaft 63. 64 and a second sealing lip 65 disposed on the sealing target fluid A side of the first sealing lip 64 and slidably in contact with the rotary shaft 63, the sealing device 61 on the sealing target fluid A side A second threaded portion 66 that performs a pumping action is provided on the sliding portion of the second seal lip 65, and this second threaded portion 66 is formed so that the contact state of the sliding portion is discontinuous in the circumferential direction. The leakage of the fluid A to be sealed to the first seal lip 64 side when allowed to stand still is allowed, and a first threaded portion 67 is also provided on the sliding portion of the first seal lip 64 to provide a pump action. This first screw part 67 is a sliding part. A sealing device 61 formed so as to leave an endless contact surface 68 continuously contacting in the circumferential direction is proposed (see the invention according to claim 2 of Patent Document 1), and the sealing according to this prior art is proposed. The device 61 has (1) the point that a second seal lip 65 is provided on the side of the fluid A to be sealed of the first seal lip 64 slidably contacting the rotating shaft 63, and (2) the first seal lip. The configuration of the present invention is the same as that of the present invention in that the screw portion 67 is provided in 64 sliding portions.
[0005]
However, in the sealing device 61 according to this prior art, as described above, the second screw portion 66 provided in the sliding portion of the second seal lip 65 on the sealing target fluid A side has a circular contact state with the circular portion. Since it is formed so as to be discontinuous in the circumferential direction and leakage of the fluid A to be sealed to the first seal lip 64 side is allowed when stationary, the second seal lip 65 is axially stationary. The structure is different from the present invention in that it sometimes does not have a sealing action.
[0006]
Therefore, in the sealing device 61 according to this prior art, the interference of the first seal lip 64 must be set to be relatively large in order to prevent fluid leakage when the shaft is stationary. Therefore, it is impossible to reduce the torque of the seal. In other words, this prior art has a different configuration from the present invention because it has a different object, and is therefore distinct from the present invention.
[0007]
[Patent Document 1]
Japanese Utility Model Publication No. 5-30638 [0008]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION In view of the above, an object of the present invention is to provide a sealing device that can achieve a low torque of a seal while having a necessary and sufficient sealing performance.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a sealing device of the present invention includes a seal body fixed to a housing, a first seal lip that is provided integrally with the seal body and that slidably contacts a rotating shaft, A sealing device having a second seal lip provided on the sealing target fluid side of the first seal lip and slidably contacting the rotating shaft, wherein the second seal lip is arranged around the entire circumference when the shaft is stationary. Then, fluid leakage is prevented by contacting the rotating shaft, and at the time of shaft rotation, the first seal lip prevents fluid leakage by exerting a pump action with a screw portion provided on the sliding portion, Thus, the first and second seal lips share the sealing action when the shaft is stationary and when the shaft rotates.
[0010]
In the sealing device of the present invention having the above-described configuration, the second seal lip on the fluid to be sealed side is in charge of the sealing action when the shaft is stationary, and the first seal lip provided with the screw portion is sealed when the shaft rotates. The first and second seal lips share the sealing action when the shaft is stationary and when the shaft rotates.
[0011]
Accordingly, as a result of the first and second seal lips sharing the sealing action when the shaft is stationary and rotating, the second seal lip on the fluid to be sealed side responsible for the sealing action when the shaft is stationary Since it is not necessary to take charge of the sealing action at the time of rotating the shaft, it is not necessary to set a large interference to the rotating shaft as in the case of taking a sealing action at the time of rotating the shaft. It becomes possible to set.
[0012]
In addition, since the first seal lip responsible for the sealing action when the shaft rotates does not need to be responsible for the sealing action when the shaft is stationary, the interference to the rotating shaft is the same as when performing the sealing action when the shaft is stopped. Need not be set large, and accordingly, the interference can be set small. In addition, since the sealing action here is performed not by the interference but by the pumping action of the screw portion, the size of the interference may be zero or slightly.
[0013]
Therefore, since the interference between the first and second seal lips can be set to be small, the interference can be set to be small for the entire sealing device, thereby reducing the tightening force. Thus, it is possible to reduce the torque.
[0014]
The present invention includes the following embodiments.
[0015]
That is, in order to achieve the above object, a part having a sealing ability and a part having a pumping ability are functionally separated, and further, by a synergistic effect of each function, a seal system configuration not bound to the concept of the minimum surface pressure, To do.
[0016]
Specifically, the second seal lip on the fluid to be sealed side has a level of interference (for example, about 1 mm) that prevents leakage when the shaft is stationary, and the other first seal lip has interference 0 or interference. In order to achieve a low torque (tightening force) as compared to the conventional model
[0017]
Further, a screw may be added to the second seal lip to further improve the reliability of the sealing performance.
[0018]
In the sealing device having the above configuration, when the shaft is stationary, the second sealing lip prevents stationary leakage, and during shaft rotation, the pumping ability of the first sealing lip screw prevents leakage. Further, during the shaft rotation, an internal pressure is generated between the first and second seal lips due to the pumping capacity of the first seal lip, and the internal pressure acts in the direction in which the second seal lip opens to further reduce the torque. Can also be achieved.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described with reference to the drawings.
[0020]
FIG. 1 shows a cross section of a main part of a sealing device 1 according to an embodiment of the present invention, and this sealing device 1 is configured as follows.
[0021]
That is, first, an annular seal body 2 for fixing the sealing device 1 to an inner periphery of a shaft hole of a housing (not shown) is provided, and a rotary shaft 3 is provided on the inner periphery side of the annular seal body 2. A first seal lip 4 slidably in contact with the peripheral surface of the rotary shaft 3 is provided integrally with the first seal lip 4 and is also slidable on the peripheral surface of the rotary shaft 3 on the side of the fluid A to be sealed. A second seal lip 5 that comes into contact with is integrally provided. Reference numeral 6 denotes a dust lip facing the atmosphere B side.
[0022]
The annular seal body 2 is formed by vulcanizing and adhering a rubber-like elastic body 8 to the outer surface of a reinforcing ring 7 made of a rigid material such as a metal having a substantially L-shaped cross section. The second seal lips 4 and 5 are integrally formed of the same material. A garter spring 9 for adjusting the interference is fitted on the outer periphery of the first seal lip 4, but the garter spring 9 may be omitted.
[0023]
Moreover, in the said sealing apparatus 1, the 1st and 2nd seal lips 4 and 5 are comprised so that a sealing effect may be shared.
[0024]
That is, first, the second seal lip 5 on the fluid A to be sealed side is configured to take charge of the sealing action when the shaft is stationary. Specifically, the size of the interference with respect to the rotating shaft 3 is set to Is set to such a size that fluid leakage at the time of rotation can be prevented but fluid leakage at the time of shaft rotation cannot be prevented (the size of the interference set on the second seal lip 5 is S ₁ , S ₂ the minimum value of the white tightening can prevent fluid _leakage, a minimum value of the white tightening can prevent fluid leakage when the shaft rotates S _3, is set to _{S 2 ≦ S 1 <S 3} .). Since the second seal lip 5 is in charge of only the sealing action when the shaft is stationary and not the sealing action when the shaft rotates, there is no need to prevent fluid leakage during shaft rotation (thus reducing torque). Possible).
[0025]
The sliding portion of the first seal lip 4 on the other atmosphere B side is provided with a screw portion 10 for pumping back the fluid (liquid) when the shaft is rotated. 4 is configured to take charge of a sealing action during shaft rotation by the pump action of the screw portion 10. The screw part 10 is arranged so that a large number of spiral ribs are arranged in the circumferential direction. The second seal lip 4 is in charge of only the sealing action at the time of rotating the shaft and is not in charge of the sealing action when the shaft is stationary. Therefore, the interference with respect to the rotating shaft 3 is almost unnecessary, and therefore the size of the interference is set to zero or a slight amount (thus, the torque can be reduced).
[0026]
In the sealing device 1 having the above configuration, the first and second seal lips 4 and 5 share the sealing action when the shaft is stationary and when the shaft rotates as described above. In both cases, the interference can be set small. Therefore, since the interference can be set small as the whole sealing device 1, the tightening force can be reduced and the torque can be reduced.
[0027]
Further, when the shaft rotates, an internal pressure is generated between the first and second seal lips 4 and 5 by the pumping action of the screw portion 10 provided on the first seal lip 4, and this internal pressure causes the second seal lip 5 to move. It acts in the direction away from the peripheral surface of the rotating shaft 3. Therefore, since the tightening force of the second seal lip 5 is further reduced, further reduction in torque can be realized.
[0028]
In addition, since the fluid that has passed through the second seal lip 5 during shaft rotation reaches the first seal lip 4 on the atmosphere B side, this causes the first seal lip 4 to lubricate and wear. Can be suppressed. Further, since the first seal lip 4 has zero or a slight amount of interference as described above, it originally has a small sliding resistance. Therefore, the wear can be suppressed also by the grease sealed as the initial lubrication between the first and second seal lips 4 and 5.
[0029]
In addition, when there is a concern about a decrease in sealing performance due to a small interference of the first seal lip 4, as shown in FIG. 2, an annular plane portion (flat portion) in which no screw is provided on the lip edge 4a. ) 11 may be provided. The annular plane portion 12 contacts the peripheral surface of the rotating shaft 3 over the entire circumference, thereby contributing to an improvement in sealing performance.
[0030]
Furthermore, as shown in FIG. 3, when the screw portion 12 is added to the sliding portion of the second seal lip 5, further reliability can be obtained with respect to the sealing performance of the sealing device 1.
[0031]
【The invention's effect】
The present invention has the following effects.
[0032]
That is, according to the sealing device of the present invention having the above configuration, since the first and second seal lips share the sealing action when the shaft is stationary and when the shaft is rotating, both the seal lips have a small interference margin. It is possible to set. Accordingly, since the interference can be set small as the whole sealing device, the tightening force can be reduced and the torque of the seal can be reduced as intended.
[0033]
In addition, when the shaft rotates, an internal pressure is generated between the first and second seal lips by the pumping action of the thread portion provided on the first seal lip, and this internal pressure causes the second seal lip to separate from the rotation shaft. Act on. Accordingly, the tightening force of the second seal lip is further reduced, so that further reduction in torque can be realized.
[0034]
In addition, since the fluid reaches the first seal lip when the shaft rotates, the first seal lip can be lubricated to suppress wear. In addition, since the first seal lip can be set to zero or a slight amount of interference, the first seal lip originally has a small sliding resistance. Therefore, the wear can be suppressed also by the grease enclosed as the initial lubrication between the first and second seal lips.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an essential part of a sealing device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of an essential part of a sealing device according to another embodiment of the present invention. FIG. 4 is a cross-sectional view of a main part of a sealing device according to a conventional example. FIG. 5 is a cross-sectional view of a main part of a sealing device according to another conventional example.
DESCRIPTION OF SYMBOLS 1 Sealing device 2 Seal main body 3 Rotating shaft 4 1st seal lip 4a Lip edge 5 2nd seal lip 6 Dustrip 7 Reinforcement ring 8 Rubber-like elastic body 9 Garter spring 10, 12 Screw part 11 Plain part

Claims (1)

A seal body (2) fixed to the housing; a first seal lip (4) provided integrally with the seal body (2) and slidably in contact with the rotary shaft (3); A sealing device (1) having a second sealing lip (5) slidably in contact with the rotating shaft (3) and provided on the sealing target fluid side of the sealing lip (4) of
When the shaft is stationary, the second seal lip (5) contacts the rotating shaft (3) over the entire circumference to prevent fluid leakage, and when the shaft rotates, the first seal lip (4) Prevents the fluid leakage by exerting a pump action with the screw portion (10) provided in the sliding portion, and thus the first and second seal lips (4) and (5) are rotated when the shaft is stationary. A sealing device characterized by sharing the sealing action with time.

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