JPH0984291A - Sealing structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the service life of an oil seal from becoming short by preventing the airtightness from deteriorating even if the oil seal is used in an environment where the pressure difference between the inside and the outside of oil seal is high. SOLUTION: An oil seal 20 is interposed between a housing 1 and a shaft 2 rotatable relatively to the housing 1 thus forming a space 21 where the oil seal can move in the axial direction between the housing 1 and the shaft 2. The oil seal 20 is provided with a shaft side tip part 20a touching the shaft 2 and a housing side lip part 20b touching the housing 1 so that the oil seal 20 can be slid in the axial direction by the pressure difference between the inside and outside thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaft seal structure. More specifically, the present invention relates to a seal structure suitable for sealing a portion where a pressure difference is generated between the inside and the outside of an oil seal, such as a shaft sealing device for a submersible motor.

[0002]

2. Description of the Related Art A drive shaft of a submersible motor used to drive a submersible pump or the like has, for example, a seal structure as shown in FIG. In this seal structure, an expanded seal accommodating portion 3 is formed in a part of the housing 1 of the submersible motor in which the drive shaft 2 is rotatably accommodated, and the seal accommodating portion 3 has a first oil seal 4 and Second oil seal 6
And two oil seals are installed back to back. Each oil seal 4 and 6 has a reinforcing ring 4 for increasing rigidity.
a and 6a are built in respectively, and are fixed by being press-fitted into the housing 1. As a result, the oil seals 4 and 6 are fixed to the housing 1 so as to keep airtightness and not to come out, while the lip portions 4b and 6b on the inner diameter side rotatably tighten and seal the drive shaft 2. It is provided. A garter spring 8 is attached to the backs of the lips 4b and 6b to supplement the spring force of the waists 4c and 6c, and is provided so as to press the lips 4b and 6b against the drive shaft 2. A grease 5 is enclosed between the first oil seal 4 and the second oil seal 6 to further improve the sealing performance. Further, the filter 7 is fitted into the opening of the seal accommodating portion 3.

On the other hand, as shown in FIG. 5, 2 arranged in the axial direction
Oil seal 10 with two lip portions 10b and 10c
There is also known a structure for sealing by. In this seal structure, the oil seal 10 is press-fitted into the housing 1 and accommodated in the seal accommodating portion 3 similarly to that shown in FIG. The oil seal 10 is the stopper 1 of the seal accommodating portion 3.
One end is fixed to 1 and the other end is fitted in the opening of the seal accommodating portion 3 and fixed by the seal retainer 12 so that it cannot move in the axial direction. In addition, the oil seal 10 has a built-in reinforcing ring 10a for increasing the rigidity, and the lip parts 10b and 10c have the garter springs 8 attached thereto.
The lip portions 10b and 10c are pressed against the drive shaft 2.

[0004]

However, in the above-mentioned seal structure, the lip portions 4b, 6b, 1 are formed when a pressure difference occurs inside and outside the oil seals 4, 6, 10.
0b and 10c may be deformed.

For example, in the seal structure shown in FIG. 4, when the water pressure outside the housing becomes relatively large due to the idling of the pump or excessive pumping of water, the second oil seal 6 is extremely pressed and the lip portion 6b may be deformed. Further, when the water pressure outside the housing becomes small, the first oil seal 4 may be extremely pressed from the inside, and the lip portion 4b may be deformed. On the other hand, in the seal structure shown in FIG. 5, one of the lip portions 10b and 10c of the oil seal 10 may be deformed due to an extreme pressure difference between the inside and the outside of the oil seal.

In any structure, the lip portion 4
The b, 6b, 10b, 10c may move or reverse, and the airtightness may be impaired. Also, by moving the lip portion, the waist portions 4c, 6c, 1
0d is greatly deformed and receives a burden. Therefore, if an excessively large pressure difference is applied for a long time, the waist portions 4c, 6c, 10d may be cracked or damaged. This becomes one of the factors that hinders the longevity of the oil seals 4, 6, 10.

Therefore, an object of the present invention is to provide a seal structure which does not reduce the airtightness and shortens the life of the oil seal even if a large pressure difference occurs between the inside and the outside of the oil seal.

[0008]

In order to achieve the above object, the seal structure according to claim 1 is a seal structure in which an oil seal is provided at a portion where the housing and the shaft move relative to each other. A space that allows the oil seal to move in the axial direction is formed between the oil seal and a shaft-side lip portion that comes into contact with the shaft and a housing-side lip portion that comes into contact with the housing are provided in the oil seal. The oil seal is slidable in the axial direction.

Therefore, when there is a pressure difference between the inside and the outside of the oil seal, the fluid on the high pressure side presses the oil seal on the low pressure side. As a result, the shaft-side lip portion slides on the shaft and the housing-side lip portion slides on the housing. Then, the oil seal is slid to the low pressure side, and the movement of the oil seal stops when the pressure difference between the inside and the outside of the oil seal is almost eliminated or the pressure difference is such that the oil seal cannot be slid. Eliminates the pressure difference. Therefore, it is possible to prevent the oil seal from being burdened by the pressure difference. At this time, even if the oil seal slides, each lip portion always comes into contact with the shaft and the housing to ensure airtightness.

When the high pressure side and the low pressure side are opposite, the high pressure side fluid slides on the oil seal toward the low pressure side. Then, the pressure difference between the inside and the outside of the oil seal is eliminated.

Further, the seal structure according to the second aspect is provided with an abutting portion which limits sliding of the oil seal in the axial direction to a certain range. Here, the contact portion may be provided on the housing or the shaft.

In this case, for example, when the outside of the oil seal has a low pressure and the inside of the oil seal has a high pressure, even if the oil seal slides, if the oil seal exceeds a certain range, it abuts on the contact portion and its movement is blocked. It does not come off from the housing. Further, when the outside of the oil seal is at a high pressure and the inside is at a low pressure, even if the oil seal is slid toward the inside of the housing, it is not pushed in more than necessary.

Further, the seal structure according to the third aspect is provided with an elastic member for urging the oil seal in the axial direction. Here, it is preferable to use a member such as a compression coil spring, a disc spring, or rubber as the elastic member.

Therefore, for example, when the oil seal is biased inward by the elastic member, the oil seal slides outward when the outside pressure is low and the inside pressure is high, Further, after abutting on the elastic member, it slides while elastically deforming it. This reduces the pressure difference between the inside and the outside of the oil seal. Moreover, the oil seal is prevented from falling off from the housing. When the pressure difference between the inside and the outside of the oil seal becomes small, the oil seal is urged to the position where the elastic member is restored. As a result, the oil seal is slid inward and returned to the original position.

On the other hand, when the oil seal is biased outward by the elastic member, the oil seal slides inward when the outside of the oil seal is at a high pressure and the inside is at a low pressure. After abutting, it slides while elastically deforming it. Then, the pressure difference between the inside and the outside of the oil seal is reduced. Also, the oil seal is prevented from being pushed deep inside. Then, when the pressure difference between the inside and the outside of the oil seal becomes small, the oil seal is urged by the elastic member and pushed back toward the original position.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The structure of the present invention will be described below in detail based on the embodiments shown in the drawings. In this embodiment, the case where the seal structure is applied to the drive shaft of the submersible motor has been described.

As shown in FIG. 1, in the seal structure of the present invention, a space 21 is provided between the housing 1 and the shaft 2 at a predetermined interval for the oil seal 20 to move in the axial direction.
The oil seal 20 is accommodated in the space 21 so as to be slidable in the axial direction. The oil seal 20 includes a shaft-side lip portion 20a that contacts the shaft 2 and a housing-side lip portion 20b that contacts the housing 1. The oil seal 20 is slidable in the axial direction without being fixed to the housing 1 and the shaft 2 by press fitting. It is fitted so that it touches. Reference numeral 20c is a metal reinforcing ring.

The shaft-side lip portions 20a are in contact with the outer peripheral surface of the shaft 2 and are formed at two locations side by side in the axial direction. And
A garter spring 8 that urges the shaft-side lip portions 20a in the diameter-reducing direction is attached to the outer peripheral portion of each shaft-side lip portion 20a.
0a is tightened. Further, the shaft 2 and the shaft side lip portion 20
“A” is rotatable with respect to each other and slidable in the axial direction.

Although the garter spring 8 is used in the present embodiment, the structure is not particularly limited to this. A structure for tightening the shaft 2 may be used. Further, in the present embodiment, the shaft-side lip portion 20a has a structure in which two portions are provided, one acting inward and the other acting outward, but it may be provided in one location or in three or more locations. I don't mind.

On the other hand, the housing side lip portion 20b is in contact with the inner peripheral surface of the housing 1 and is provided with two portions each of which is inclined inward and outward.

In this embodiment, the housing-side lip portions 20b are provided in two places, one for the inward direction and the other for the outward direction. Any other lip structure may be used. In addition, the shaft side lip portion 20 of the present embodiment
It may have a structure in which it branches inward and outward from one location like a. Furthermore, a garter spring that urges the housing-side lip portion 20b in the radial direction may be attached to press the housing-side lip portion 20b against the inner peripheral surface of the housing 1. Further, the shaft-side lip portion 20a and the housing-side lip portion 20b may be provided with a dust lip as needed. According to this structure, dust does not enter between the oil seal 20 and the shaft 2 and the housing 1, so that the lip portions 20a and 20b are not damaged and the airtightness is not impaired. It should be noted that the innermost one and the outermost one of the housing-side lip portions 20b of the present embodiment may be dustproof lips.

Therefore, the frictional force between the shaft side lip portion 20a and the shaft 2 and the frictional force between the housing side lip portion 20b and the inner peripheral surface of the housing 1 can be adjusted and set to each other. it can. For example, by increasing the frictional force of the oil seal 20 with respect to the housing 1, the oil seal 20 may be provided so as not to rotate when the shaft 2 rotates, or conversely, may be provided so as to rotate together with the shaft 2.

On the other hand, the housing 1 has an oil seal 20.
An abutting portion 22 is provided to limit the sliding of the shaft in the axial direction within a certain range. For example, the abutting portion 22 is formed by an inward flange that projects toward the shaft 2 in the opening of the housing 1. Therefore, when the oil seal 20 slides and reaches the opening, it abuts the abutting portion 22 and is prevented from jumping out of the housing 1. In the present embodiment, the contact portion 22 formed in the opening of the housing 1
However, in order to set the sliding range of the oil seal 20, it may be provided inside the housing on the opposite side or at another position. For example, a protrusion may be formed as a contact portion at a predetermined position inside the housing 1 to limit the sliding of the oil seal 20 in both directions. In this case, the projecting portion may have a shape that is circumferentially continuous with the inner circumferential surface of the housing 1 or a shape that is provided at several circumferentially discontinuous locations. Further, the abutting portion is connected to the housing
It is also possible to provide an O-ring inside. Furthermore, a protrusion may be provided on the outer periphery of the shaft 2 to form the contact portion.

According to the seal structure constructed as described above, the pressure difference between the inside and the outside of the oil seal is eliminated as follows. When the shaft 2 or the housing 1 is rotated, slippage occurs in the circumferential direction between the shaft side lip portion 20a and the shaft 2 or between the housing side lip portion 20b and the housing 1. The shaft side lip portion 2 of the oil seal 20 is provided between the shaft 2 and the housing 1 which rotate relative to each other.
0a and shaft 2 contact, and housing side lip portion 20
The contact between b and the housing 1 constitutes a seal.

When a pressure difference is generated between the inside and the outside of the oil seal 20, the fluid on the high pressure side presses the oil seal 20 toward the low pressure side with the oil seal 20 interposed therebetween. As a result, the oil seal 20 slides, and the internal volume of the oil seal 20 changes. Then, the pressure inside and outside the oil seal 20 becomes equal and the force pressing the oil seal 20 does not act, so the sliding of the oil seal 20 is stopped. In this state, the fluid pressure acting on the oil seal 20 is balanced, and therefore the oil seal 20 is not burdened.

The above-described embodiment is an example of a preferred embodiment of the present invention, but the present invention is not limited to this, and various modifications can be made without departing from the gist of the present invention. For example, as shown in FIGS. 2 and 3, a return spring 23, which is a compression coil spring, is provided between the contact portion 22 of the housing 1 and the oil seal 20 on the low pressure side inside and outside the oil seal 20. You can also

According to this structure, when there is almost no pressure difference between the inside and the outside of the housing 1, the oil seal 20 does not press the return spring 23, which is an elastic member, as shown in FIG. On the other hand, when the external pressure becomes relatively smaller than the internal pressure, the oil seal 20 slides outward as shown in FIG. Slide while deforming. Further, since the outer end of the return spring 23 is in contact with the contact portion 22, it does not jump out of the housing 1. In addition, the oil seal 2
When the external pressure of 0 approaches the internal pressure, the stored force of the return spring 23 pushes the oil seal 20 back, and the pressure difference causes the oil seal 20 to return to the original position. Therefore, even if the pressure fluctuation is repeated, the oil seal 20 is always returned to the original position, so that the sliding is not limited.

Although the return spring 23 is arranged only on the outer side of the oil seal 20 in this embodiment, it may be arranged on the inner side. According to this structure, the external pressure of the oil seal becomes larger than the internal pressure, and the oil seal 20 slides inward. Also in this case, when the pressure difference between the inside and the outside of the oil seal 20 becomes small, the force of the return spring 23 returns the oil seal 20 to the original position. In addition, a retractable return spring may be connected to the oil seal so as to correspond to both the inside and outside directions.

As the elastic member, a spring such as a disc spring can be used instead of the compression coil spring. Also,
Instead of the spring, an elastic body such as rubber may be used.
Therefore, it is possible to select an elastic member having an optimum shape and type according to the shape of the oil seal 20.

In this embodiment, the case where the seal structure is used in the submersible motor has been described. However, even in another device, the seal structure is applied to a portion where a pressure difference occurs between the inside and the outside of the seal. can do.

[0031]

As is apparent from the above description, in the seal structure according to the first aspect, when a pressure difference is generated between the inside and the outside of the oil seal, the fluid on the high pressure side axially presses the oil seal to the low pressure side. Since it slides, there is no pressure difference between the inside and outside of the oil seal. Therefore, the load given to the oil seal from the fluid is reduced. Further, since the deformation of the oil seal is prevented, the airtightness is ensured and the life of the oil seal can be extended. Moreover, even if the oil seal slides on the shaft or the housing, the lip portions are always in contact with the shaft or the housing, so that the intrusion or leakage of the fluid can be reliably prevented.

Further, in the seal structure according to the second aspect, since the contact portion that limits the sliding of the oil seal in the axial direction to a certain range is provided, the pressure difference between the inside and the outside of the oil seal becomes extremely large. However, problems such as the oil seal coming off the housing will not occur.

Further, in the seal structure according to the third aspect, since elastic members such as a compression coil spring and a disc spring are provided,
Even if the pressure fluctuation is repeated, the oil seal always returns to the original position, and the sliding of the oil seal is not restricted.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of a seal structure of the present invention.

FIG. 2 is a vertical cross-sectional view showing another embodiment of the seal structure of the present invention, showing a state where the oil seal is in the original position.

FIG. 3 is a vertical cross-sectional view showing another embodiment of the seal structure of the present invention, showing a state in which the oil seal presses the biasing means.

FIG. 4 is a vertical cross-sectional view showing a conventional seal structure.

FIG. 5 is a vertical cross-sectional view showing another conventional seal structure.

[Explanation of symbols]

 1 Housing 2 Shaft 20 Oil Seal 20a Shaft-side lip portion 20b Housing-side lip portion 21 Oil seal axial movement space 22 Abutment portion 23 Return spring (elastic member)

Claims (3)

[Claims] 1. A seal structure in which an oil seal is provided at a portion where a housing and a shaft move relative to each other, and a space is formed between the housing and the shaft to allow axial movement of the oil seal. The oil seal is provided with a shaft-side lip portion that comes into contact with the shaft and a housing-side lip portion that comes into contact with the housing, and the oil seal is slidable in the axial direction due to a pressure difference between the inside and the outside of the oil seal. Characteristic seal structure. 2. The seal structure according to claim 1, further comprising an abutting portion that limits sliding of the oil seal in the axial direction within a certain range. 3. The seal structure according to claim 1, further comprising an elastic member for urging the oil seal in an axial direction.