JP7649740B2 - Sealed structure - Google Patents

Description

The present invention relates to a sealing device.

Gaskets have been known as sealing devices that seal gaps between multiple opposing components that cannot move relative to each other, such as a housing and a cover. The gasket is attached to an annular space, such as an annular groove, formed between multiple components. Such a gasket forms a sealing structure together with the applicable component that forms the annular space to which it is attached. As an example of such a gasket, a gasket has been disclosed that has a cylindrical reinforcing ring that extends in the axial direction of the ring around the axis, and an elastic body portion made of an elastic body attached to the reinforcing ring, and this elastic body portion has a pair of lip portions that extend along the axis from both ends in the axial direction of the reinforcing ring (see, for example, Patent Document 1).

In recent years, efforts have been made to make gaskets smaller and lighter in the components to which they are applied. This has resulted in smaller cross-sections of the gasket itself and thinner and more plastic components being used for the gasket. Reducing the cross-section of the gasket and reducing the thickness and plasticity of the components to which the gasket is applied reduces the annular space in which the gasket is attached, increasing the relative variation in the dimensions of the space due to manufacturing. With such gaskets, it is conceivable that the intended sealing performance of the gasket may not be achieved due to the variation in the dimensions of the annular space in which the gasket is attached. Technology to address such cases has also been disclosed (see, for example, Patent Document 2).

Japanese Utility Model Application Publication No. 6-32834 International Publication No. 2015/137491

However, as with the technology of Patent Document 2, depending on the dimensions of the annular space and the lip portion, it was sometimes impossible to obtain the intended sealing performance. In other words, there was room for improvement in the sealing performance of conventional sealing devices.

The present invention has been made in consideration of the above-mentioned problems, and its object is to provide a sealing device that can improve sealing performance.

In order to achieve the above object, the sealing device of the present invention is a sealing device for sealing an annular space formed by a plurality of components, and comprises a reinforcing ring annular about an axis, and an elastic body portion annular about the axis formed from an elastic body attached to the reinforcing ring, the elastic body portion having an outer peripheral side portion covering the reinforcing ring from the outer peripheral side, an annular seal lip portion protruding from the outer peripheral side portion toward one side in the axial direction, and an annular secondary seal portion protruding from the outer peripheral side portion toward the other side in the axial direction, the seal lip portion protruding toward the one side of the reinforcing ring in the axial direction and protruding toward the outer peripheral side of the reinforcing ring in the radial direction.

In a sealing device according to one embodiment of the present invention, the seal lip portion has a clamping margin relative to the multiple members in the radial direction.

In a sealing device according to one aspect of the present invention, the seal lip portion protrudes radially outwardly toward the outer circumferential side portion.

In a sealing device according to one embodiment of the present invention, the seal lip portion has a clamping margin relative to the multiple members in the axial direction.

In a sealing device according to one embodiment of the present invention, the secondary lip portion protrudes to the other side of the reinforcing ring in the axial direction.

The sealing device of the present invention can improve sealing performance.

1 is a cross-sectional view taken along an axis of a sealing device according to an embodiment of the present invention. 2 is a schematic diagram of a cross section taken along an axis for illustrating a difference in shape between the sealing device shown in FIG. 1 and a mounting space of a sealing structure to which the sealing device is mounted. FIG. FIG. 2 is a cross-sectional view showing a state in which the sealing device shown in FIG. 1 is used. 4 is a cross-sectional view taken along the axis of a sealing device according to a reference example. FIG. FIG. 5 is a cross-sectional view showing a state in which the sealing device according to the reference example shown in FIG. 4 is used.

Below, the embodiment of the present invention is explained with reference to the drawings.

Figure 1 is a cross-sectional view of a sealing device 1 according to an embodiment of the present invention taken along axis x.

For ease of explanation, the direction of arrow a (see FIG. 1) in the direction of axis x (one side in the axial direction) is defined as the outer side, and the direction of arrow b (see FIG. 1) in the direction of axis x (the other side in the axial direction) is defined as the inner side. Also, in the direction perpendicular to axis x (hereinafter also referred to as the "radial direction"), the direction away from axis x (arrow c direction in FIG. 3) is defined as the outer periphery side, and the direction approaching axis x (arrow d direction in FIG. 3) is defined as the inner periphery side.

As shown in FIG. 1, a sealing device 1 according to an embodiment of the present invention includes a reinforcing ring 10 that is annular about the axis x, and an elastic body portion 20 that is annular about the axis x and is formed from an elastic body attached to the reinforcing ring 10. The elastic body portion 20 has an outer peripheral side portion 23 that is a portion that covers the reinforcing ring 10 from the outer peripheral side c, and a seal lip 21 that is an annular portion that protrudes from the outer peripheral side portion 23 toward the other side (inner side b) in the axis x direction. The elastic body portion 20 also has a sub-lip portion 22 that is an annular portion that protrudes from the outer peripheral side portion 23 toward one side (outer side a) in the axis x direction. The seal lip 21 protrudes toward one side beyond the reinforcing ring 10 in the axis x direction, and protrudes toward the outer peripheral side c beyond the reinforcing ring 10 in the radial direction that is perpendicular to the axis x direction. The sealing device 1 will be specifically described below.

As shown in FIG. 1, the reinforcing ring 10 is a tubular member extending along the axis x. The reinforcing ring 10 is, for example, a cylindrical or approximately cylindrical member with the axis x as its central axis or approximately central axis. The reinforcing ring 10 has a reinforcing ring outer end 12 which is the end of the inner side b, and a reinforcing ring outer end 12 which is the end of the outer side a. The reinforcing ring 10 is a member that reinforces the elastic body portion 20. The reinforcing ring 10 is formed, for example, from a metal material. Examples of the metal material of the reinforcing ring 10 include stainless steel and SPCC (cold rolled steel). When the reinforcing ring 10 is formed from a resin material, examples of the resin material include nylon 66 (PA66) and polyphenylene sulfide (PPS) resin.

The elastic body portion 20 is formed to cover the reinforcing ring 10. As described above, the elastic body portion 20 has a seal lip portion 21, a sub-lip portion 22, and an outer peripheral side portion 23. The elastic body portion 20 also has a base portion 24, which is a portion of the inner peripheral side d of the outer peripheral side portion 23. The base portion 24 is a portion that covers the reinforcing ring 10 from the inner peripheral side d. The seal lip portion 21 and the sub-lip portion 22 each extend from the base portion 24. Specifically, the seal lip portion 21 extends from the inner end portion (base inner end 24b) of the base portion 24. The sub-lip portion 22 extends from the outer end portion (base outer end 24a) of the base portion 24.

As shown in FIG. 1, the outer peripheral side portion 23 is a portion that covers the reinforcing ring 10 from the outer peripheral side c. The outer peripheral side portion 23 has an outer peripheral side outer end 23a, which is the end portion on the outer side a, connected to the sub-lip portion 22. The outer peripheral side portion 23 has an inner peripheral side inner end 23b, which is the end portion on the inner side b, connected to the seal lip portion 21. The outer peripheral side portion 23 also has a shoulder portion 23c at the outer peripheral side outer end 23a that is connected to the sub-lip portion 22. The shoulder portion 23c forms a corner portion on the outer peripheral side. The shoulder portion 23c is a portion defined by an annular surface facing the outer side a and an outer peripheral surface portion 23d, which is a cylindrical surface facing the outer peripheral side c.

The seal lip portion 21 protrudes obliquely from the outer circumferential side inner end 23b and the base inner end 24b toward the inside (arrow b direction) and the outer circumferential side (arrow c direction). The seal lip portion 21 expands in diameter, for example, toward the inside b in the axial x direction. The degree of expansion of the seal lip portion 21 is not particularly limited. The seal lip portion 21 is a conical or approximately conical cylindrical shape with the axial x as its central axis or approximately central axis. The seal lip portion 21 protrudes toward the inside b from the reinforcing ring inner end 11. The seal lip portion tip 21a, which is the end of the inner b of the seal lip portion 21, is located on the inside b from the reinforcing ring inner end 11 in the axial x direction. The elastic body portion 20 of the sealing device 1 may be formed so as to expand in diameter from the outer circumferential surface portion 23d of the outer circumferential side portion 23 toward the seal lip portion tip 21a. Furthermore, the elastic body portion 20 of the sealing device 1 may have a constant degree of diameter expansion from the outer peripheral surface portion 23d of the outer peripheral side portion 23 toward the seal lip portion tip 21a. Furthermore, the elastic body portion 20 may have a different degree of diameter expansion at each portion from the outer peripheral surface portion 23d toward the seal lip portion tip 21a. The seal lip portion tip 21a is thinner than the seal lip portion root 21b. The seal lip portion root 21b is a portion that connects to the base portion 24. The seal lip portion 21 may become thinner, for example, from the seal lip portion root 21b toward the seal lip portion tip 21a.

2 is a schematic diagram of a cross section along the axis x1 to show the difference in shape between the sealing device 1 and the mounting space S of the sealing structure to which the sealing device 1 is attached. In FIG. 2, the sealing device 1 and the mounting space S are superimposed on each other in a cross section along the axis x1 to show the difference in shape and size between the sealing device 1 and the mounting space S to which the sealing device 1 is attached. As shown in FIG. 2, the length of the elastic body portion 20 including the seal lip portion 21 and the sub-lip portion 22 in the axial x direction of the sealing device 1 is longer than the length of the mounting space S. The seal lip portion 21 has a seal lip portion tip 21a that protrudes inward b from the reinforcing ring 10 and the outer peripheral surface portion 23d of the outer peripheral side portion 23 in the axial x direction. In addition, the seal lip portion 21 protrudes radially toward the outer peripheral side c from the reinforcing ring 10 and the outer peripheral surface portion 23d of the outer peripheral side portion 23. In other words, the seal lip portion 21 has a length and an outer peripheral surface that allows it to come into contact with the inner seal surface 113b, which is the seal surface on the inner side b, and the outer peripheral wall surface 113a, which is the seal surface on the outer peripheral side c, with a predetermined interference in a usage state described below. Note that the length of the seal lip portion 21 is the width in the extension direction (projection direction) of the seal lip portion 21.

For example, as shown in FIG. 1, the sub-lip portion 22 protrudes obliquely from the base outer end 24a toward the outside (arrow a direction) and the inner circumferential side (arrow d direction). Specifically, the sub-lip portion 22 is a portion that reduces in diameter toward the outside a in the axis x direction. The sub-lip portion 22 is a conical or approximately conical cylindrical portion with the axis x as its central axis or approximately central axis. The sub-lip portion 22 protrudes toward the outside a from the reinforcement ring outer end 12. The sub-lip portion tip 22a, which is the end of the outside a of the sub-lip portion 22, is located outside a from the reinforcement ring outer end 12 in the axis x direction. The sub-lip portion tip 22a is thinner than the sub-lip portion root 22b, which is the portion connected to the base 24. The sub-lip portion 22 becomes thinner, for example, from the sub-lip portion root 22b toward the sub-lip portion tip 22a. The sub-lip portion 22 has a length such that it comes into contact with the seal surface on the outside a with a predetermined interference when in use as described below.

The sub-lip portion 22 may also be an annular protrusion that protrudes from the base outer end 24a of the base 24 to the outer side a. Specifically, the sub-lip portion 22 is an annular or approximately annular protrusion centered or approximately centered on the axis x. In this case as well, the sub-lip portion 22 protrudes outward a beyond the reinforcing ring outer end 12. Furthermore, the sub-lip portion tip 22a, which is the end of the outer side a of the sub-lip portion 22, is located outward a beyond the reinforcing ring outer end 12 in the direction of the axis x. The sub-lip portion 22 is formed so as to contact the inner sealing surface with a predetermined crushing margin in the usage state described below.

As shown in FIG. 1, the elastic body portion 20 does not cover the reinforcing ring outer end 12. The elastic body portion 20 may be flush with the reinforcing ring outer end 12 in the radial direction. The elastic body portion 20 does not have to be flush with the reinforcing ring outer end 12 in the radial direction. The elastic body portion 20 may also cover the reinforcing ring outer end 12. In this case, the sub-lip portion tip 22a is formed so as to be located outward a from the portion of the elastic body portion 20 that covers the reinforcing ring outer end 12 in the direction of the axis x.

The elastic body of the elastic body portion 20 may be, for example, various rubber materials. Examples of the various rubber materials include synthetic rubbers such as nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM).

The reinforcing ring 10 is manufactured, for example, by pressing or forging. The elastic body portion 20 is molded by cross-linking (vulcanization) molding using a mold. During this cross-linking molding, the reinforcing ring 10 is placed in the mold. The elastic body portion 20 is bonded to the reinforcing ring 10 by cross-linking adhesion. Through the above steps, the elastic body portion 20 and the reinforcing ring 10 are molded integrally.

Next, a state in which the above-mentioned sealing device 1 is used will be described.
FIG. 3 is a cross-sectional view showing a state in which the sealing device 1 is used. As shown in FIG. 3, the sealing device 1 is attached to a mounting space S, which is an annular space, and is in a state of use. The mounting space S is, for example, a circular or approximately circular space around an axis x1 formed by a cover 100 and a housing 110 as a plurality of members. The cover 100 has a through hole 101 formed therein. The housing 110 has a through hole 111 to which the cover 100 is fixed formed therein. A groove portion 113 that forms an annular groove around the through hole 111 is formed in the housing surface 112. The groove portion 113 is defined by an outer peripheral wall surface 113a and an inner seal surface 113b. The outer peripheral wall surface 113a extends in a cylindrical or approximately cylindrical shape in the direction of the axis x1. The inner seal surface 113b is an annular flat surface that extends from the inner end of the outer peripheral wall surface 113a toward the inner peripheral side to the through hole 111.

The cover 100 is fixed to the housing 110 so that its cover surface 102 faces the housing surface 112. The cover 100 is also fixed to the housing 110 so that its through hole 101 is coaxial or approximately coaxial with the through hole 111 of the housing 110. The through hole 101 and the through hole 111 communicate with each other to form one through pipe 120. In the cover surface 102, the annular flat surface is the outer seal surface 102a. The outer seal surface 102a faces the inner seal surface 113b of the housing 110 in the direction of the axis x1. The mounting space S is an annular space defined by the outer seal surface 102a, the outer peripheral wall surface 113a, and the inner seal surface 113b. The sealing device 1 is attached to this mounting space S to seal the mounting space S. The sealing device 1 seals a through pipe 120 formed by the through hole 101 and the through hole 111 .

In the use state, the sealing device 1 is attached to the mounting space S coaxially or approximately coaxially with the mounting space S. In other words, in the use state, the axis x and axis x1 of the sealing device 1 shown in FIG. 1 overlap or are slightly misaligned.

The reinforcing ring outer end 12 contacts the outer seal surface 102a. The secondary lip portion 22 is pressed against the outer seal surface 102a and contacts the outer seal surface 102a with a predetermined interference or squeeze.

As described above, in the sealing device 1, the length of the elastic body portion 20 including the seal lip portion 21 and the sub-lip portion 22 is longer than the length of the mounting space S in the axial x direction. Therefore, as shown in FIG. 3, the elastic body portion 20 of the sealing device 1 is sandwiched and compressed between the cover 100 and the housing 110 in the use state. The seal lip portion 21 protrudes inward b from the reinforcing ring 10 and the outer peripheral surface portion 23d of the outer peripheral side portion 23 in the axial x direction. Therefore, the seal lip portion 21 has the seal lip portion tip 21a pressed toward the outer side a by the inner seal surface 113b. In other words, the seal lip portion 21 contacts the inner seal surface 113b with a predetermined range of tightening from the seal lip portion tip 21a in the axial x direction.

The seal lip portion 21 protrudes radially toward the outer circumferential side c beyond the reinforcing ring 10 and the outer circumferential surface portion 23d of the outer circumferential side portion 23. The seal lip portion 21 has a seal lip portion tip 21a that presses the outer circumferential wall surface 113a toward the outer circumferential side c . In other words, the seal lip portion 21 contacts the outer circumferential wall surface 113a and the outer circumferential wall surface 113a with a predetermined range of interference from the seal lip portion tip 21a in the radial direction.

As described above, the seal lip portion 21 can contact the inner seal surface 113b, which is the seal surface on the inner side b, and the outer wall surface 113a, which is the seal surface on the outer circumferential side c, with a predetermined interference when in use. Here, the seal lip portion 21 is longer than the sub-lip portion 22. For this reason, the seal lip portion 21 can contact the inner seal surface 113b with a relatively large interference when in use, as shown in FIG. 3.

Therefore, even if there is variation in the dimensions of the mounting space S of the sealing device 1, the seal lip portion 21 absorbs this variation. Variation in the dimensions of the mounting space S is, for example, variation in the width dimension in the direction of the axis x1 (the distance between the inner seal surface 113b and the outer seal surface 102a). This allows the sealing device 1 to maintain a state of contact with the outer peripheral wall surface 113a and the inner seal surface 113b. This also allows the sub-lip portion 22 to be maintained in a state pressed against the outer seal surface 102a. This also allows the sub-lip portion 22 to maintain a state of contact with the outer seal surface 102a.

In this way, by being attached to the mounting space S in the intended orientation, the sealing device 1 can properly seal the mounting space S even if there is variation in the dimensions of the mounting space S.

Figure 4 is a cross-sectional view of the sealing device 2 according to the reference example taken along the axis x. Figure 5 is a cross-sectional view showing the sealing device 2 according to the reference example in use.

As shown in FIG. 4, the sealing device 2 according to the reference example differs from the sealing device 1 according to the above-mentioned embodiment in the position where the seal lip portion is provided in the elastic body portion 220. The sealing device 2 according to the reference example differs from the sealing device 1 in the shape of the seal lip portion 221 and the sub-lip portion 222. Specifically, the seal lip portion 221 protrudes obliquely from the outer end 224a of the base portion 224 toward the outside (arrow a direction) and the inner circumferential side (arrow d direction). For example, the seal lip portion 221 is reduced in diameter toward the inner circumferential side d as it moves toward the outside a in the axis x direction. The seal lip portion 221 is a conical or approximately conical cylindrical portion with the axis x as the central axis or approximately the central axis. For example, the sub-lip portion 222 protrudes obliquely from the inner end 224b of the base portion 224 toward the inside (arrow b direction) and the inner circumferential side (arrow d direction).

As shown in Figure 5, when the sealing device 2 is in use, the seal lip portion 221 is pressed inward by the outer seal surface 202a of the cover surface 202. The seal lip portion 221 is in contact with the outer seal surface 202a with a predetermined range of interference from the tip 221a. The sub-lip portion 222 is pressed against the inner seal surface 213b of the housing surface 212 and in contact with the inner seal surface 213b with a predetermined interference or crushing margin.

The sealing device 2 according to the reference example as described above is formed so that the seal lip portion 221 is reduced in diameter toward the inner circumferential side d as it moves toward the outer side a in the axial x direction. Therefore, in the state of use, the tip 221a of the seal lip portion 221 moves toward the inner circumferential side d along the outer seal surface 202a due to the elastic force of the elastic body portion 20. In such a state of use, the sealing device 2 according to the reference example may not be able to obtain the intended sealing performance because the tip 221a of the seal lip portion 221 moves from the outer seal surface 202a. In particular, in the sealing device 2 according to the reference example, when there is variation in the width dimension in the axial x1 direction in the mounting space S (the distance between the inner seal surface 113b and the outer seal surface 102a), the pressing force of the seal lip portion 221 or the sub-lip portion 222 against the seal surface is insufficient. That is, in the sealing device 2, the pressing force of the seal lip portion 221 against the outer seal surface 202a or the pressing force of the sub-lip portion 222 against the inner seal surface 213b is insufficient. As a result, in the sealing device 2, the seal lip portion 221 moves from the outer seal surface 202a, and the intended sealing performance may not be obtained.

In addition, the sealing device 2 according to the reference example does not have a portion in the seal lip portion 221 or the like that comes into contact with the outer peripheral wall surface 213a of the housing surface 212 on the outer peripheral side c, as does the seal lip portion 21 of the sealing device 1. For this reason, the sealing device 2 may not be able to obtain the intended sealing performance on the outer peripheral side c.

On the other hand, the sealing device 1 is formed such that the seal lip portion 21 protrudes inward b from the reinforcing ring 10 and the outer peripheral surface portion 23d of the outer peripheral side portion 23 in the axial x direction. Therefore, the seal lip portion tip 21a of the seal lip portion 21 presses the inner seal surface 113b toward the outer side a. Also, the sealing device 1 is formed such that the seal lip portion 21 protrudes in the radial direction toward the outer peripheral side c from the reinforcing ring 10 and the outer peripheral surface portion 23d of the outer peripheral side portion 23. Therefore, the seal lip portion tip 21a presses the outer peripheral wall surface 113a toward the outer peripheral side c . That is, in the sealing device 1, the seal lip portion tip 21a moves toward the corner portion 113c where the inner seal surface 113b and the outer peripheral wall surface 113a of the housing 110 are joined by the elastic force of the elastic body portion 20. Therefore, the sealing device 1 can suppress the seal lip portion tip 21a from moving from the inner seal surface 113b to improve the sealing performance.

Furthermore, according to the sealing device 1, when there is variation in the width dimension in the axis x1 direction in the mounting space S (the distance between the inner seal surface 113b and the outer seal surface 102a) in the usage state, it is possible to suppress a shortage of the pressing force applied to the seal surface by the seal lip portion 21 or the sub-lip portion 22. Specifically, the sealing device 1 can suppress a shortage of the pressing force applied to the outer seal surface 102a by the seal lip portion 21 or the pressing force applied to the inner seal surface 113b by the sub-lip portion 22.

In other words, the sealing device 1 can provide stable sealing performance by preventing the seal lip portion 21 from moving from the outer seal surface 102a, which would cause the intended sealing performance to be lost.

In the sealing device 1, the seal lip portion 21 is formed to protrude radially toward the outer periphery side c beyond the reinforcing ring 10 and the outer periphery surface portion 23d of the outer periphery side portion 23, so that the seal lip portion tip 21a presses the outer periphery wall surface 113a toward the inner periphery side d. Therefore, according to the sealing device 1, the contact area of the seal lip portion 21 can be increased to improve the sealing performance.

In addition, in the sealing device 1, the seal lip portion 21 contacts the inner seal surface 113b and the outer peripheral wall surface 113a with a predetermined tightening margin when in use. Therefore, the sealing device 1 can exert a centering effect in which the elastic force of the elastic body portion 20 is exerted toward the corner portion 113c of the housing 110 by various forces such as vibration when in use. Therefore, the sealing device 1 can suppress the occurrence of a gap between the housing 110.

As described above, the sealing device 1 according to the embodiment of the present invention can improve sealing performance.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-mentioned embodiments of the present invention, and includes all aspects included in the concept and scope of the claims of the present invention. Furthermore, each configuration may be appropriately and selectively combined so as to achieve at least some of the above-mentioned problems and effects. For example, the shape, material, arrangement, size, etc. of each component in the above-mentioned embodiments may be appropriately changed depending on the specific usage mode of the present invention.

1...sealing device, 10...reinforcing ring, 11...inner end of reinforcing ring, 12...outer end of reinforcing ring, 20...elastic body portion, 21...seal lip portion, 21a...tip of seal lip portion, 21b...root of seal lip portion, 22...secondary lip portion, 22a...tip of secondary lip portion, 22b...root of secondary lip portion, 23...outer peripheral side portion, 23a...outer peripheral side portion outer end, 23b...inner peripheral side portion inner end, 23c...shoulder portion, 23d...outer peripheral surface portion, 24...base portion, 24a...outer base end, 24b...inner base end, 100...cover, 101...through hole, 102...cover surface, 102a...outer seal surface, 110...housing, 111...through hole, 112...housing surface, 113...groove portion, 113a...outer peripheral wall surface, 113b...inner seal surface, 113c...corner portion, 120...through tube

Claims (1)

a cover and a housing, and a sealing device for sealing an annular space formed by fixing an outer surface of the housing and an inner surface of the cover to each other without any gap;
A sealing structure comprising:
the annular space is defined by an outer peripheral wall surface that is defined by the housing and that extends cylindrically in the axial direction, an inner seal surface that is an annular plane that extends from an inner end of the outer peripheral wall surface toward an inner peripheral side to a through hole of the housing, and an outer seal surface that is an annular plane that is defined by the cover,
The sealing device includes:
A reinforcing ring annularly formed around the axis;
an elastic body portion having an annular shape around the axis and formed of an elastic body attached to the reinforcing ring;
The elastic body portion is
the reinforcing ring has an outer circumferential side portion that covers the reinforcing ring from an outer circumferential side, an annular seal lip portion that protrudes inward in the axial direction from the outer circumferential side portion, and an annular sub-lip portion that protrudes outward in the axial direction from a base portion that covers the reinforcing ring from an inner circumferential side,
The reinforcing ring has an outer end contacting the outer seal surface,
The outer circumferential side portion contacts the outer circumferential wall surface in a usage state,
The seal lip portion protrudes radially so as to be enlarged toward the outer periphery side more than the outer periphery side portion, and has a length in the axial direction longer than the sub-lip portion, and protrudes toward the inside of the reinforcing ring with a length such that in a used state the seal lip portion contacts the inner seal surface in the axial direction with a predetermined interference, and protrudes outer periphery than the reinforcing ring with a length such that in a used state the seal lip portion contacts the outer periphery wall surface in the radial direction with a predetermined interference. As a result, a tip of the seal lip portion is formed so as to press the inner seal surface toward a corner where the inner seal surface and the outer periphery wall surface are joined to maintain a contact state with the inner seal surface,
The secondary lip portion is configured to press against the outer seal surface to maintain contact with the outer seal surface.
Sealed structure.

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