Sealing device

A sealing device between a shaft hole formed on a housing and a rotary shaft, is provided with a rotating seal member fixed to the rotary shaft that rotates integrally with the rotary shaft, and a fixed seal member fixed to an inner surface of the shaft hole. The fixed seal member has a lip contacting the rotary shaft and an axial dust lip contacting the rotating seal member. The rotating seal member is formed by a rigid body, and an opening is formed on the rotating seal member connecting to a space defined by the rotary shaft, the lip and the axial dust lip of the fixed seal member, and the rotating seal member. A deformation member is disposed on the opening of the rotating seal member that has higher elasticity than the rotating seal member, which blocks the opening, and deforms based on the pressure in the space.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit and priority of Japanese Application No. 2016-156205, filed Aug. 9, 2016. The entire disclosure of the above application is incorporated herein by reference.

FIELD

The present disclosure relates to a sealing device used in an apparatus having a rotary shaft.

BACKGROUND

Conventionally, such sealing device is known, for example, in Japanese Unexamined Patent Application Publication No. 2006-57825. In the sealing device, a sealing structure is known having a rotating seal member2known-as a deflector, fixed to a rotary shaft1, and a fixed seal member4fixed to an inner surface of a shaft hole3in which the rotary shaft1is disposed, as illustrated inFIG. 12. The rotating seal member2is formed from a rigid body, and the fixed seal member4has a compound structure of a rigid body and an elastic body.

This kind of sealing device is used in a driving system unit or other apparatus of a vehicle such as, for example, an automobile. While the fixed seal member4mainly seals a lubricant in a machine internal space S, the rotating seal member2mainly prevents the infiltration of foreign substances such as mud or dust from the outside of the machine A to the machine internal space S.

The fixed sealing member4has a seal lip4A and a side dust lip4B that contact the rotary shaft, and an axial dust lip4C the contacts the rotating seal member2. The seal lip4A mainly has the role of sealing lubricant in the machine internal space S, and the dust lips4B and4C mainly have the role of preventing the infiltration of foreign substances from the outside of the machine A to the machine internal space S.

SUMMARY

[Problem to be Solved by the Disclosure]

In the conventional sealing device illustrated inFIG. 12, the internal pressure of a space O defined by the rotary shaft1, the dust lips4B and4C of the fixed seal member4, and the rotating seal member2may largely fluctuate. As causes for this pressure fluctuation, for example, a change in the relative positional relationship between the fixed seal member4fixed on the shaft hole3and the rotating seal member2fixed on the rotary shaft1accompanying the movement in the thrust direction of the rotary shaft1is given. Furthermore, the expansion and contraction of air, and an unexpected change in the relative positional relationship between the fixed seal member4and the rotating seal member2due to the eccentricity of the fixed seal member4to the rotating seal member2, which accompany temperature change in the space O, are also considered to be causes of pressure fluctuation. Particularly in differential devices where there is a lot of movement in the thrust direction of the rotary shaft, the relative positional relationship between the fixed seal member4and the rotating seal member2changes considerably, and the internal pressure of the space O fluctuates remarkably.

When the internal pressure of the space O rises, the contact pressure given by the side dust lip4B to the rotary shaft1rises, and the contact pressure given by the axial dust lip4C to the rotating seal member2also rises.

Because of this, there is a risk that the torque given by the entire sealing device to the rotary shaft1will rise.

An object of the present disclosure is to provide a sealing device that can appropriately block the outside of the machine A and the machine internal space S, and suppress a rise in torque given to the rotary shaft.

[Means for Solving the Problem]

In light of the above, the sealing device according to the present disclosure is a sealing device that seals between a shaft hole formed on a housing and a rotary shaft, provided with a rotating seal member fixed to the rotary shaft that rotates integrally with the rotary shaft, and a fixed seal member fixed to an inner surface of the shaft hole, wherein the fixed seal member has a lip contacting the rotary shaft and an axial dust lip contacting the rotating seal member, the rotating seal member is formed by a rigid body, an opening is formed on the rotating seal member connecting to a space defined by the rotary shaft, the lip and the axial dust lip of the fixed seal member, and the rotating seal member, and a deformation member is disposed on the opening of the rotating seal member that has higher elasticity than the rotating seal member, blocks the opening, and deforms based on the pressure in the space.

In this sealing device, the deformation member is disposed on the opening formed on the rotating seal member, and the deformation member deforms based on the pressure in the space defined by the rotary shaft, the lip and the axial dust lip of the fixed seal member, and the rotating seal member. Therefore, a rise in pressure in the space is softened, and a rise in torque given to the rotary shaft as a result of this rise in pressure is softened.

It is preferable for the opening to be formed on a position not blocked by the rotary shaft. In this configuration, the deformation member disposed on the opening deforms without being hindered by the rotary shaft.

It is preferable for the rotating seal member to have an inner side tube portion fixed to the rotary shaft, an outer side tube portion disposed on an outer side of the inner side tube portion, and a side wall portion that connects the inner side tube portion and the outer side tube portion, the opening to be formed on the side wall portion, and the deformation member to be stretched from the inner circumferential surface of the inner side tube portion across the outer circumferential surface of the outer side tube portion. In this configuration, the contact surface area of the deformation member and the rotating seal member is largely secured, and the adhesion between the two can also be highly secured. In other words, the deformation member is difficult to be peeled, particularly fatigue-peeled, from the rotating seal member, and the life of the sealing device can be made longer. Furthermore, the adhesion between the inner side tube portion and the rotary shaft is improved by the deformation member being disposed on the inner circumferential surface of the inner side tube portion, and the sealing ability can be improved.

It is preferable for at least the portion of the deformation member covering the opening to be bellows-shaped. In this case, it is easy for the deformation member to expand based on a rise in pressure in the space, and the rise in pressure in the space can be effectively suppressed.

[Effect of the Disclosure]

In the present disclosure, the deformation member is disposed on the opening formed on the rotating seal member, and the deformation member deforms based on the pressure in the space defined by the rotary shaft, the lip and the axial dust lip of the fixed seal member, and the rotating seal member. Therefore, a rise in pressure in the space is suppressed, and a rise in torque given to the rotary shaft as a result of this rise in pressure is softened. This effect is particularly advantageous when the sealing device according to the present disclosure is used in a differential device where there is a lot of movement in the thrust direction of the rotary shaft because the relative positional relationship of the fixed seal member and the rotating seal member changes considerably.

DETAILED DESCRIPTION

Various embodiments according to the present disclosure will be described below referring to drawings.

First Embodiment

FIG. 1is a diagram according to the first embodiment of the present disclosure, and illustrates a sealing device used in an apparatus having a rotary shaft, for example, a driving system unit of a vehicle such as an automobile (for example, transmission, transfer device, differential device).

This sealing device10seals between a rotary shaft14and the inner surface of a shaft hole16formed on a housing in which the rotary shaft14is inserted and disposed, and prevents or reduces fluid from leaking from a machine internal space S to outside the machine A. The rotary shaft14is substantially cylindrical, the shaft hole16is circle shaped in a cross-section, and the sealing device10is substantially ring-shaped, but only the upper-side portions thereof are illustrated inFIG. 1.

The sealing device10is an assembly that is a combination of a rotating seal member18called a deflector that rotates integrally with the rotary shaft14fixed to the rotary shaft14, and a fixed seal member20fixed to the inner surface of the shaft hole16. The rotating seal member18and the fixed seal member20seal lubricant in the machine internal space S cooperating with each other. However, while the fixed seal member20mainly seals lubricant in the machine internal space S, the rotating seal member18mainly prevents the infiltration of foreign substances such as mud or dust from the outside of the machine A to the machine internal space S.

The fixed seal member20has an elastic body, for example, an elastic ring22formed by an elastomer, and a rigid body that reinforces the elastic ring22, for example, a metal reinforcing ring24having a cross-section that is substantially L-shaped. The reinforcing ring24has one portion thereof embedded in the elastic ring22, and is adhered to the elastic ring22. In other words, the fixed seal member20has a compound structure made up of the elastic ring22and the reinforcing ring24.

In the drawings, the fixed seal member20is illustrated in a state in which it is not installed on the apparatus, and in which it is not receiving any external force. However, when the fixed seal member20is actually installed on the apparatus, the portion of the elastic ring22(for example, seal lip32, side dust lips34and36, and axial dust lip40described hereinafter) is deformed by receiving a reaction force from a contacting member.

The fixed seal member20has an outer side ring body26fixed on the shaft hole16, an inner side ring body28on the inner side of the radial direction of the outer side ring body26, and a side wall30that connects the outer side ring body26and the inner side ring body28. The outer side ring body26is a portion configured by the elastic ring22and the reinforcing ring24, the side wall30is also a portion configured by the elastic ring22and the reinforcing ring24, and the inner side ring body28is a portion configured only by the elastic ring22.

The outer ring body26is the outer side seal portion fixed to the inner circumferential surface of the shaft hole16. The fixing method is not limited, but may be, for example, carried out by close-fit. The portion of the reinforcing ring24extending to the left and right inFIG. 2, or in other words, the tube-shaped portion is inserted into the shaft hole16. One portion of the elastic ring22is disposed on the outer side of a portion of the tube-shape of the reinforcing ring24, and the reinforcing ring24strongly presses this portion of the elastic ring22against the inner circumferential surface of the shaft hole16.

The fixed seal member20has the seal lip32and the side dust lips34and36that protrude to the inner side in the radial direction of the inner side ring body28. The seal lip32and the side dust seal lips34and36are all formed by only elastic bodies. While the seal lip32is a projection connected to the circumferential direction and has two tilted surfaces, the side dust lips34and36are thin plate-shaped circular rings expanding diagonally to the outside of the machine A aligned together.

The seal lip32and side dust lips34and36all contact the outer circumferential surface of the rotary shaft14. When the rotary shaft14rotates, the seal lip32and the side dust lips34and36all slide relatively with respect to the rotary shaft14. However, the seal lip32mainly has the role of sealing lubricant in the machine internal space S, the side dust lips34and36mainly have the role of preventing the infiltration of foreign substances from the outside of the machine A to the machine internal space S.

A garter spring38is wound around the inner side ring body28for compressing the inner side ring body28to the inner side in the radial direction. A receiving groove that receives the garter spring38is formed on the inner side ring body28. The garter spring38applies a force to the seal lip32that presses the seal lip32to the rotary shaft14.

Furthermore, the fixed seal member20has an axial dust lip40that extends from the side wall30to the outside of the machine A and to the outer side in the radial direction. The axial dust lip40contacts the inner circumferential surface of an outer side tube portion50of the rotating seal member18.

The rotating seal member18is formed by a rigid body, for example, metal. The rotating seal member18has an inner side tube portion46fixed to the rotary shaft14, an outer side tube portion50disposed on the outer side of the inner side tube portion46, and a side wall portion48that connects the inner side tube portion46and the outer side tube portion50. As described above, the rotating seal member18mainly prevents the infiltration of foreign substances such as mud or dust from the outside of the machine A to the machine internal space S. Specifically, the rotating seal member18rotates integrally with the rotary shaft14, and drives away foreign substances. The axial dust lip40of the fixed seal member20contacts the inner circumferential surface of the outer side tube portion50of the rotating seal member18, and mainly has the role of preventing the infiltration of foreign substances from the outside of the machine A to the machine internal space S.

The rotary shaft14, the side dust lip36and the axial dust lip40of the fixed seal member20, and the rotating seal member18define a space52. An opening54that connects to the space52is formed on the side wall portion48of the rotating seal member18. A deformation member56is disposed on the opening54of the rotating seal member18that has higher elasticity than the rotating seal member18, blocks the opening54, and deforms based on the pressure in the space52.

When there is no opening54, the pressure in the space52may fluctuate largely.

When the pressure in the space52rises, the contact pressure given by the side dust lip36to the rotary shaft14rises, and the contact pressure given by the axial dust lip40to the rotating seal member18also rises. Because of this, there is concern that the torque given by the entire sealing device to the rotary shaft14will rise.

However, according to this embodiment, the deformation member56provided on the opening54deforms based on the pressure in the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed. This effect is particularly advantageous when the sealing device10is used in a differential device where there is a lot of movement in the thrust direction of the rotary shaft14because the relative positional relationship of the fixed seal member20and the rotating seal member18changes drastically.

From the above perspective, it is preferable for the deformation member56to be easier to deform than the side dust lip36and the axial dust lip40when the pressure in the space52rises. Furthermore, it is preferable for the deformation member56to have a strength and water resistance to not be damaged as much as possible by foreign substances such as mud and dust. It can be said that these characteristics are also in the deformation member of other embodiments described hereinafter.

Elastomers such as ethylene propylene rubber (EPDM), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), fluorine rubber (FKM) and the like, and resins such as polyethylene, polyvinyl chloride and the like, are examples of materials for the deformation member56. The deformation member56is preferably film-shaped, and the thickness thereof is designed considering the elasticity, strength, and the like of the materials. It can be said that these characteristics are also in the deformation member of the other embodiments described hereinafter.

As a method for providing the deformation member56on the opening54, for example, the deformation member56may be adhered to the periphery of the opening54using an adhesive. Alternatively, the deformation member56may be joined to the periphery of the opening54using a cross-link of materials of the deformation member56. Alternatively, the rotating seal member18may be disposed in-mold, and the material of the deformation member56may be filled in this mold, and if necessary, the material of the deformation member56may be crosslinked. If appropriate, it can be said that these methods are also in the deformation member of the other embodiments described hereinafter.

It is preferable that the opening54is formed on a position not sealed by the rotary shaft14so that the deformation member56disposed on the opening54can be deformed without being hindered by the rotary shaft14. In this embodiment illustrated inFIG. 1, the rotary shaft14has a step portion58and a flange60. The side wall portion48of the rotating seal member18is separated from the flange60in the axial direction of the rotary shaft14, and is separated from the outer circumferential surface of the step portion58in the radial direction of the rotary shaft14. Because of this, the deformation member56disposed on the opening54can be deformed without being hindered by the step portion58or flange60of the rotary shaft14along with the rise in pressure in the space52.

FIG. 2is a frontal view of the rotating seal member18viewed along the arrow II ofFIG. 1. InFIG. 2, numeral50A illustrates the outer circumferential surface of the outer side tube portion50of the rotating seal member18, and numeral46A illustrates the inner circumferential surface of the inner side tube portion46. As illustrated inFIG. 2, four openings54and four deformation members56are provided, and the openings54and the deformation members56are fan-shaped.

FIG. 3is a frontal view of the rotating seal member18according to a variation. In this variation, four openings54and four deformation members56are provided, and the openings54and the deformation members56are circular.

However, the number of openings54and the number of deformation members56are not limited, and may, for example, be one. Furthermore, the shape, size, and gaps of the opening54and the deformation member56are not limited.

In the other embodiments (except the sixth embodiment illustrated inFIG. 8) described hereinafter, the openings54illustrated inFIG. 2andFIG. 3may be used. Furthermore, the number, shape, size, and gaps of the opening54are not limited in these embodiments.

Second Embodiment

FIG. 4illustrates a sealing device70according to the second embodiment of the present disclosure. In the drawings ofFIG. 4and after, the same numerals are used to illustrate components in common with the first embodiment, and detailed descriptions of such components will not be given.

In this sealing device70, a deformation member76is provided on the opening54replacing the deformation member56. As in the first embodiment, the deformation member76provided on the opening54deforms based on the internal pressure of the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed.

The deformation member76is stretched from the inner circumferential surface of the inner side tube portion46of the rotating seal member18across the outer circumferential surface of the outer side tube portion50, covering the opening54. In this configuration, the contact surface area of the deformation member76and the rotating seal member18is largely secured, and the adhesion between the two can also be highly secured. In other words, the deformation member76is difficult to be peeled, particularly fatigue peeled, from the rotating seal member18, and the life of the sealing device76can be made longer. Furthermore, the adhesion between the inner side tube portion46and the rotary shaft14is improved by the deformation member76being disposed on the inner circumferential surface of the inner side tube portion46, and the sealing ability can be improved.

Third Embodiment

FIG. 5illustrates a sealing device80according to the third embodiment of the present disclosure. In this sealing device80, a deformation member86is provided on the opening54replacing the deformation member56. As in the first embodiment, the deformation member86provided on the opening54deforms based on the internal pressure of the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed.

The deformation member86is stretched from the outer circumferential surface of the inner side tube portion46of the rotating seal member18across the inner circumferential surface of the outer side tube portion50, covering the opening54. In this configuration, the contact surface area of the deformation member86and the rotating seal member18is largely secured, and the adhesion between the two can also be highly secured. In other words, the deformation member86is difficult to be peeled, particularly fatigue peeled, from the rotating seal member18, and the life of the sealing device86can be made longer.

However, it is preferable for the deformation member86to be disposed on a position not contacting a tip end of the axial dust lip40of the fixed seal member20along with the movement of the thrust direction of the rotary shaft1. Therefore, it is not necessary for the deformation member86to extend to the inner circumferential surface of the outer side tube portion50, and the function can be achieved as long as the deformation member86covers at least the opening54.

Fourth Embodiment

FIG. 6illustrates a sealing device90according to the fourth embodiment of the present disclosure. In this sealing device90, a deformation member96is provided on the opening54replacing the deformation member56. As in the first embodiment, the deformation member96provided on the opening54deforms based on the internal pressure of the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed.

The deformation member96is formed by a film, and is bellows-shaped. Therefore, it is easy for the deformation member to expand based on a rise in pressure in the space52, and the rise in pressure in the space52can be effectively suppressed.

The materials of the deformation member96can be selected from the same materials as in the deformation member56of the first embodiment. The thickness of the deformation member96is designed considering the elasticity, strength of the materials, and the like. As a method for providing the deformation member96on the opening54, for example, the deformation member96may be adhered to the periphery of the opening54using an adhesive. Alternatively, the deformation member96may be joined to the periphery of the opening54using a cross-link of materials of the deformation member96.

Fifth Embodiment

FIG. 7illustrates a sealing device100according to the fifth embodiment of the present disclosure. In this sealing device100, a deformation member106is provided on the opening54replacing the deformation member56. As in the first embodiment, the deformation member106provided on the opening54deforms based on the internal pressure of the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed.

The deformation member106is stretched from the inner circumferential surface of the inner side tube portion46of the rotating seal member18across the outer circumferential surface of the outer side tube portion50. Furthermore, the deformation member106is formed by a film, and the portion corresponding to the opening54is bellows-shaped. In other words, the deformation member106is a combination of the deformation member76in the second embodiment (FIG. 4) and the deformation member96in the fourth embodiment (FIG. 6). Therefore, this embodiment has the effects of the second and fourth embodiment.

Sixth Embodiment

FIG. 8illustrates a sealing device110according to the sixth embodiment of the present disclosure. In this sealing device110, no opening is provided on the side wall portion48of the rotating seal member18and an opening114is formed on the outer side tube portion50replacing this. The opening114connects to the space52. A deformation member116is disposed on the opening114, has higher elasticity than the rotating seal member18, blocks the opening114, and deforms based on the pressure in the space52.

As in the first embodiment, the deformation member116provided on the opening114deforms based on the internal pressure of the space52. Therefore, a rise in pressure in the space52is suppressed, and a rise in torque given to the rotary shaft14as a result of the rise in pressure is suppressed. In this embodiment, it is possible to dispose the opening114on a position not blocked by the rotary shaft14hardly effecting the shape of the rotary shaft14, and the deformation member116disposed on the opening114deforms without being hindered by the rotary shaft14(for example, the flange60).

Seventh Embodiment

FIG. 9illustrates a sealing device120according to the seventh embodiment of the present disclosure. In this sealing device120, a bellows-shaped deformation member126formed by a film is disposed on an opening124provided on the side wall portion48. To widen the contact surface area between the deformation member126and opening124, a projecting wall128is formed around the opening124. By widening the contact surface area between deformation member126and the opening124, the adhesion between the two can be highly ensured. In other words, the deformation member126is difficult to be peeled, particularly fatigue peeled, from the opening124of the rotating seal member18, and the life of the sealing device120can be made longer.

The materials of the deformation member126can be selected from the same materials as in the deformation member56of the first embodiment. The thickness of the deformation member126is designed considering the elasticity, strength of the materials, and the like. As a method for providing the deformation member126on the opening124, for example, the deformation member126may be adhered to the periphery of the opening124using an adhesive. Alternatively, the deformation member126may be joined to the periphery of the opening124using a cross-link of materials of the deformation member126.

Eighth Embodiment

FIG. 10illustrates a sealing device130according to the eighth embodiment of the present disclosure. In this sealing device130, a deformation member136is disposed on the opening54of the side wall portion48of the rotating seal member18. The peripheral portion of the deformation member136has a thickness larger the other portions of the deformation member136, and a groove138having the peripheral portion inlayed therein of the opening54is formed on the peripheral portion. By the peripheral portion of the opening54being inlayed into the groove138of the peripheral portion of the deformation member136, the deformation member136is hard to be separated from the rotating seal member18, and the life of the sealing device130can be made longer.

FIG. 11illustrates a sealing device140according to the eighth embodiment of the present disclosure. In this sealing device140, the thickness of a central portion of the deformation member136is smaller than the thickness of the central portion of the deformation member136illustrated inFIG. 10. Furthermore, the thickness of the central portion of the deformation member136is smaller than the film thickness of the rotating seal member18. Because of this, the elasticity of the central portion of the deformation member136is high.

Various embodiments of the present disclosure were described above, but these descriptions do not limit the present disclosure, and various modifications are considered including, deletion, addition, and replacing of components in the technical scope of the present disclosure.

For example, the shape of the fixed seal member20is not limited to that illustrated in the drawings. The present disclosure can be applied to a fixed seal member having a lip contacting the rotary shaft14and an axial dust lip contacting the rotating seal member18, provided with a space similar to the space52. For example, at least one of the side dust lips34and36may be omitted, or an additional lip may be added. The shape of the lips are also not limited to that illustrated in the drawings.

A number of the embodiments and variations described above may be combined as long as they do not contradict each other.

The characteristic that the portion corresponding to the opening54of the deformation member of the fifth embodiment (FIG. 7) being bellows-shaped may be applied to the deformation member86in the third embodiment (FIG. 5), the deformation member116in the sixth embodiment (FIG. 8), and the deformation member136inFIG. 11.

A projecting wall similar to the projecting wall128in the seventh embodiment (FIG. 9) may be provided around the opening114in the sixth embodiment (FIG. 8).

The shape of the deformation member136in the eight embodiment (FIG. 10,FIG. 11) may be applied to the deformation member116in the sixth embodiment (FIG. 8).

DESCRIPTION OF THE REFERENCE NUMERALS