Sealing member and sealing structure using the same

Abstract

To provide a sealing member capable of improving sealing performance while suppressing damages, and a sealing structure using the sealing member.SOLUTION: A sealing member 1 is equipped with an annular base portion 10 that is fitted in an annular attachment groove 4 provided so as to open a first surface 3 of an inner peripheral surface 6 of an outer peripheral member 5 and an outer peripheral surface 3 of an inner peripheral member 2 opposite in a diametrical direction, an annular lip portion 12 that is provided so as to extend from the base portion toward a second surface 6 of the inner peripheral surface and the outer peripheral surface and to diagonally extend to a sealed space 7 side that is one side in an axial direction and that is side contact with second surface, and a communication groove 15 that is provided in a sliding portion 13 of the lip portion and extends in an extending direction of the lip portion. The communication groove is formed so as to be changed from a communication state communicating spaces on both sides in the axial direction to a non-communication state in which a peripheral edge portion 16 of the communication groove abuts on the second surface due to deformation of the lip portion accompanied with a pressure rise on the sealed space side.SELECTED DRAWING: Figure 1

Description

TECHNICAL FIELD

[0001] The present invention relates to a sealing member and a sealing structure using the same. BACKGROUND ART

[0002] Conventionally, sealing members are known that seal between the inner peripheral surface of an outer peripheral member and the outer peripheral surface of an inner peripheral member that face each other in the radial direction. For example, Patent Document 1 below discloses a sealing device including an annular body portion mounted in an annular groove provided in a cylinder, and an inner peripheral lip configured to extend from the body portion toward one axial side and the inner peripheral side, with a distal end brought into close contact with the outer peripheral surface of a piston. PRIOR ART DOCUMENTS PATENT DOCUMENTS

[0003] PATENT DOCUMENT 1 Japanese Unexamined Patent Application Publication No. 2015-137729 SUMMARY OF THE INVENTION PROBLEMS TO BE SOLVED BY THE INVENTION

[0004] However, in the sealing device described in Patent Document 1, if the gas remaining on the sealed space side is compressed by a rapid pressure rise on the sealed space side, which is the side where the inner peripheral lip extends, there is a concern that the temperature on the sealed space side rises sharply, making the sealing device prone to local carbonization and melting.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide a sealing member capable of improving sealing performance while suppressing damage, and a sealing structure using the same. MEANS FOR SOLVING THE PROBLEMS

[0006] To achieve the above objective, the sealing member configuration 1 according to the present invention comprises: an annular base portion that fits into an annular mounting groove provided that opens on the inner circumferential surface of radially opposing outer peripheral members and on the first surface of the outer circumferential surface of the inner circumferential member; an annular lip portion provided that extends diagonally from the base portion toward the second surface of the inner circumferential surface and toward the sealed space on one side in the axial direction, and that slides against the second surface; and a communication groove provided on the sliding contact portion of the lip portion and extending in the direction of extension of the lip portion, wherein the communication groove is formed such that it moves from a communicating state that connects the spaces on both sides in the axial direction to a non-communicating state when the peripheral edge of the communication groove comes into contact with the second surface due to deformation of the lip portion caused by a pressure increase in the sealed space.

[0007] The following description of embodiments reveals that the sealing member according to the present invention may have the following dependent configurations. <Configuration 2> In configuration 1, the communication groove may be provided such that it opens at the tip surface of the lip portion and the bottom surface of the groove is parallel to the surface of the sliding contact portion of the lip portion. <Structure 3> In configuration 2, both groove side walls of at least the opening portion of the tip surface of the communication groove may be formed in an expanding manner from the groove bottom surface side. <Structure 4> In configuration 2 or 3, a recess that opens on the tip surface may be provided on the side of the lip portion opposite to the side where the communication groove is provided in the radial direction. <Composition 5> In any one of configurations 1 to 4, the lip portion may be formed such that its thickness decreases towards the tip. <Composition 6> In any one of configurations 1 to 5, the lip portion may be formed such that its entire tip surface is located on the second surface side of the first surface in the radial direction.

[0008] To achieve the above objective, the sealing structure according to the present invention is a sealing structure that uses a sealing member according to the present invention to seal the space between an outer peripheral member and an inner peripheral member, configured such that the pressure in the sealed space on one side in the axial direction increases with relative axial movement, characterized in that the base of the sealing member is fitted into an annular mounting groove provided to open on the first surface of the radially opposing inner and outer peripheral surfaces of the outer peripheral member and the inner peripheral member, and the lip portion of the sealing member is in contact with the second surface of the inner and outer peripheral surfaces. [Effects of the Invention]

[0009] The sealing member and sealing structure using the same according to the present invention, with the configuration described above, can improve sealing performance while suppressing damage. [Brief explanation of the drawing]

[0010] [Figure 1] (a) and (b) schematically show an example of a sealing member and a sealing structure using the same according to one embodiment of the present invention, where (a) is a schematic plan view and (b) is a schematic cross-sectional view corresponding to the view taken by the arrow XX in (a). [Figure 2] (a) to (c) are schematic cross-sectional views of a partial fracture corresponding to the view along the YY line in Figure 1(a). [Figure 3] (a) and (b) schematically show a modified example of the sealing structure and are partial fractured schematic cross-sectional views corresponding to the view along the YY line in Figure 1(a). [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. In some of the figures, some of the detailed symbols used in other figures have been omitted. Figures 1 to 3 schematically show an example of a sealing member according to this embodiment, as well as an example and modified example of a sealing structure using this sealing member.

[0012] As shown in Figure 1, the sealing member 1 according to this embodiment includes an annular base portion 10 that fits into an annular mounting groove 4 which is provided to open on the first surface (in this embodiment, the outer surface 3) of the radially opposing outer peripheral member 5 and outer peripheral member 2. The sealing member 1 is provided to extend diagonally from the base portion 10 toward the second surface (in this embodiment, the inner peripheral surface 6) of the inner peripheral surface 3 and toward the sealed space 7 on one axial side, and is in sliding contact with the inner peripheral surface 6. The sealing structure according to this embodiment uses the sealing member 1 to seal the space between the outer peripheral member 5 and the inner peripheral member 2, configured such that the pressure in the sealed space 7 on one side of the axial direction increases with relative axial movement. The inner peripheral member 2 and outer peripheral member 5 may be a cylindrical cylinder in which the outer peripheral member 5 constitutes a cylindrical cylinder, and the inner peripheral member 2 is a piston that reciprocates within the outer peripheral member 5. In this case, the oil that lubricates the reciprocating motion of the inner peripheral member 2 may be sealed on the side of the sealed space 7.

[0013] As shown in Figure 1(b), the outer peripheral member 5 is in the shape of a bottomed cylinder. The inner circumferential member 2 is cylindrical and arranged coaxially within the outer circumferential member 5. A gap is formed around the entire circumference between the outer circumferential surface 3 of the inner circumferential member 2 and the inner circumferential surface 6 of the outer circumferential member 5, allowing the inner circumferential member 2 to reciprocate. The sealing member 1 seals this gap between the outer circumferential surface 3 of the inner circumferential member 2 and the inner circumferential surface 6 of the outer circumferential member 5. The mounting groove 4 of the inner circumferential member 2 opens radially outward on the outer circumferential surface 3 and extends around the entire circumference. The shape of this mounting groove 4, when viewed in the longitudinal direction of the groove, is rectangular. The sealed space 7 is defined by the bottom surface of the outer peripheral member 5, the axial end surface of the inner peripheral member 2 facing this bottom surface, and the inner peripheral surface 6 of the outer peripheral member 5. If the inner peripheral member 2 moves so that its axial end surface is closer to the bottom surface of the outer peripheral member 5, the fluid in the sealed space 7 is compressed and the pressure in the sealed space 7 increases.

[0014] The base portion 10 of the sealing member 1 is shaped to be fittable into the mounting groove 4. This base portion 10 has a substantially cylindrical shape coaxial with the inner peripheral side member 2. This base portion 10 has a substantially square shape when viewed in a radial cross section (a cross section cut along the radial direction). The dimension of this base portion 10 along the axial direction is set to a dimension corresponding to the groove width dimension of the mounting groove 4. The dimension of this base portion 10 along the axial direction may be substantially the same as the groove width dimension of the mounting groove 4, or may be a slightly smaller dimension. The dimension of this base portion 10 along the radial direction is set to a dimension smaller than the groove depth dimension of the mounting groove 4. In the illustrated example, the dimension of the base portion 10 along the radial direction is set to be smaller than the dimension along the axial direction. A recessed step portion 11 is provided at the inner peripheral edge of the end portion on the other axial side, which is the side opposite to the sealed space 7 side in the axial direction of the base portion 10. This recessed step portion 11 is formed such that the diameter of the end portion on the other axial side of the base portion 10 is larger than that on the one axial side.

[0015] The lip portion 12 of the sealing member 1 is provided so as to extend obliquely from the end portion on the other axial side of the above-described base portion 10 toward the radially outer side and the sealed space 7 side. In a natural state (a state where no elastic deformation occurs), this lip portion 12 has a substantially truncated conical cylindrical shape that expands in diameter toward the sealed space 7 side. An annular groove 18 opening toward the one axial side is formed over the entire circumference by the lip portion 12 and the base portion 10. As shown in FIG. 2, the sliding contact portion 13 of this lip portion 12 is provided with a communication groove 15 extending in the extending direction of the lip portion 12.

[0016] As shown in Figs. 2(b), 2(c), 3(a) and 3(b), the communication groove 15 is formed such that from a communication state in which the spaces on both axial sides are in communication with each other, the peripheral edge portion 16 of the communication groove 15 is brought into abutment with the inner peripheral surface 6 by the deformation of the lip portion 12 accompanying the pressure rise on the sealed space 7 side, so as to establish a non-communication state. With such a configuration, in a state where no pressure rise occurs on the sealed space 7 side or in an initial state where a pressure rise occurs, the gas remaining on the sealed space 7 side can be discharged through the communication groove 15, and the gas remaining on the sealed space 7 side can be reduced. When the lip portion 12 deforms as the pressure on the sealed space 7 side rises, the peripheral edge portion 16 of the communication groove 15 abuts against the inner peripheral surface 6 to establish the non-communication state, so that sealing performance can be improved. Since the gas on the sealed space 7 side is discharged and reduced through the communication groove 15 before the non-communication state is established in this manner, rapid temperature rise due to gas compression is less likely to occur, and damage to the sealing member 1 can be suppressed.

[0017] The communication groove 15 opens at the distal end surface 14 of the lip portion 12. With such a configuration, when the interference is small such that the distal end portion of the lip portion 12 slightly abuts against the inner peripheral surface 6, the spaces on both axial sides can be brought into communication with each other via the opening on the distal end surface 14 side of the communication groove 15 and the portion in the vicinity thereof. Further, when the lip portion 12 deforms as the pressure on the sealed space 7 side rises, the distal side edge portion 16a, which is the edge portion on the opening side of the distal end surface 14 of the communication groove 15, abuts against the inner peripheral surface 6 to establish the non-communication state (see Fig. 2(c)). The specific configuration of the communication groove 15 will be described later. As shown in Fig. 2(a), the lip portion 12 is formed such that the thickness decreases toward the distal end. With such a configuration, the distal end side of the lip portion 12 is easily deformed, and the peripheral edge portion 16 of the communication groove 15 easily abuts against the inner peripheral surface 6. That is, the lip portion 12 is formed such that the thickness of the distal end side portion is smaller than the thickness of the base portion 10 side portion.

[0018] The lip portion 12 is formed such that, in the radial direction, its entire tip surface 14 is located on the inner circumferential surface 6 side of the outer circumferential member 5, rather than on the outer circumferential surface 3 of the inner circumferential member 2. With this configuration, the lip portion 12 can more easily receive the pressure rise on the sealed space 7 side, and the lip portion 12 can deform more quickly. As a result, the peripheral edge 16 of the communication groove 15 can more easily come into contact with the inner circumferential surface 6. In this embodiment, the lip portion 12 is formed such that, when the sealing member 1 is assembled to the inner circumferential member 2 and the outer circumferential member 5, its entire tip surface 14 is located on the inner circumferential surface 6 side of the outer circumferential member 5, rather than on the outer circumferential surface 3 of the inner circumferential member 2. With this configuration, the lip portion 12 can more effectively receive the pressure rise on the sealed space 7 side. In other words, the thickness dimension of the tip of the lip portion 12 is set to be smaller than the gap dimension between the outer circumferential surface 3 of the inner circumferential member 2 and the inner circumferential surface 6 of the outer circumferential member 5.

[0019] On the side of the lip portion 12 opposite to the side where the communication groove 15 is provided in the radial direction, a recess 17 is provided that opens on the tip surface 14. With this configuration, the tip side of the lip portion 12 is easily deformed, and even when the clamping force is small, such that the tip of the lip portion 12 only slightly abuts against the inner circumferential surface 6, the tip edge 16a on the tip surface 14 side of the communication groove 15 can be quickly brought into contact with the inner circumferential surface 6. This recess 17 may be provided only in the area where the communication groove 15 described later is provided, but in this embodiment, it is provided around the entire circumference. This recess 17 is provided so as to form a recessed step on the inner circumferential edge of the tip of the lip portion 12. In other words, this recess 17 is formed so that the inner circumferential side of the tip of the lip portion 12 is larger in diameter than the base portion 10 side. In the example recess 17 shown in the figure, the dimension L2 along the extension direction of the lip portion 12 is smaller than the groove length (dimension along the extension direction) L1 of the communication groove 15, which will be described later. More specifically, recess 17 is formed so that the dimension L2 along the extension direction of the lip portion 12 is smaller than half the groove length L1 of the communication groove 15. Also, in the example recess 17 shown in the figure, the dimension along the thickness direction of the lip portion 12 is smaller than the dimension along the thickness direction of the lip portion 12 in the communication groove 15.

[0020] As shown in Figure 1(a), the communication grooves 15 are provided at multiple locations with intervals in the circumferential direction. In this embodiment, an example is shown in which multiple (six in the illustrated example) communication grooves 15 are provided at equal intervals from each other. Since these communication grooves 15 have similar configurations, one will be used as an example in the following explanation. As shown in Figure 2(a), the communication groove 15 is provided such that its groove bottom surface 15a is parallel to the surface 13a of the sliding contact portion 13 of the lip portion 12. With this configuration, for example, compared to a configuration where the groove depth of the communication groove 15 increases towards the opening side of the tip surface 14, it is possible to ensure communication when the interference fit is large, while at the time when the interference fit is small, the tip side edge 16a of the communication groove 15 on the tip surface 14 side is more likely to come into contact with the inner circumferential surface 6. In other words, the groove depth of this communication groove 15 is uniform over approximately the entire length in the longitudinal direction of the groove. In the illustrated example, the groove back side surface 15c at the end of the communication groove 15 opposite to the tip surface 14 in the longitudinal direction is shown as an inclined surface that slopes downward from the surface 13a towards the groove bottom surface 15a.

[0021] As shown in Figure 1(a), both groove side walls 15b, 15b of the opening portion of at least the tip surface 14 of the connecting groove 15 are formed in an expanding shape from the groove bottom surface 15a side. In other words, at least the opening portion of the tip surface 14 of the connecting groove 15 is formed such that the groove width increases as it moves from the groove bottom surface 15a side toward the side wall edges 16b, 16b that become the edges on the surface 13a side of both groove side walls 15b, 15b. With this configuration, for example, compared to a configuration where the opening portion of the tip surface 14 of the connecting groove 15 is rectangular, the tip side edge 16a on the tip surface 14 side of the connecting groove 15 is more likely to come into contact with the inner circumferential surface 6 even when the interference fit is small. In the illustrated example, the connecting groove 15 is approximately V-shaped when viewed in the longitudinal direction of the groove. In other words, the intersection of both groove side walls 15b, 15b becomes the groove bottom surface 15a. The side walls 15b, 15b of the connecting groove 15 only need to be formed in an expanded shape at least on the end surface 14 side, but in this embodiment, they are formed in an expanded shape over approximately the entire length in the longitudinal direction of the groove.

[0022] The groove width of the communication groove 15 may be uniform over approximately its entire length in the longitudinal direction of the groove. The groove width, groove depth, and groove length L1 of the communication groove 15 should be set to appropriate dimensions so that the spaces on both axial sides can communicate when there is no pressure rise on the sealed space 7 side and in the initial state when a pressure rise occurs. The groove width, groove depth, and groove length L1 of the communication groove 15 should be set to appropriate dimensions so that the peripheral edge 16 of the communication groove 15 comes into contact with the inner circumferential surface 6 due to the deformation of the lip portion 12 caused by the pressure rise, resulting in a non-communication state. In the illustrated example, the groove length L1 of the communication groove 15 is shown to be approximately 1 / 2 of the extension dimension of the lip portion 12. The peripheral edge 16 of the connecting groove 15 includes the aforementioned front edge 16a, the aforementioned side wall edges 16b, 16b on both sides, and the rear edge 16c which is the edge on the surface 13a side of the groove's inner side 15c. This sealing member 1 is integrally formed from an elastic material such as rubber. The material of the rubber used in this sealing member 1 is not particularly limited, but examples include NBR, H-NBR, EPDM, ACM, AEM, FKM, silicone rubber, etc.

[0023] An example of a sealing structure using the sealing member 1 configured as described above is shown in Figures 2(b) and (c). In this structure, the base portion 10 of the sealing member 1 is fitted into the mounting groove 4 of the inner circumferential member 2, and the lip portion 12 of the sealing member 1 is in contact with the inner circumferential surface 6. With this configuration, even when the pressure in the sealed space 7 increases due to the movement of the inner circumferential member 2 as described above, gas can be discharged through the communication groove 15 of the lip portion 12 of the sealing member 1. Therefore, since the amount of gas in the sealed space 7 is reduced, a rapid rise in temperature due to gas compression is less likely to occur, and damage to the sealing member 1 can be suppressed. In addition, as the lip portion 12 deforms in response to the pressure increase in the sealed space 7, the peripheral edge 16 of the communication groove 15 comes into contact with the inner circumferential surface 6 as described above, thereby improving the sealing performance.

[0024] The example in Figure 2 illustrates a case where the clamping force is smaller compared to the modified example described later. In this example, as shown in Figure 2(b), when the inner circumferential member 2 is stationary and in the initial state of movement, the tip of the lip portion 12 is slightly in contact with the inner circumferential surface 6. In this state, the side wall edges 16b, 16b of the tip surface 14 side portion of the communication groove 15 are slightly in contact with the inner circumferential surface 6, while the side wall edges 16b, 16b and the back edge 16c of the groove's inner side 15c portion are not in contact with the inner circumferential surface 6, and the spaces on both sides in the axial direction are in communication via the communication groove 15. From this state, as shown in Figure 2(c), when the inner circumferential member 2 moves, the pressure in the sealed space 7 increases, and coupled with the inflow of fluid from the sealed space 7 into the annular groove 18, the lip portion 12 deforms so as to be pressed against the inner circumferential surface 6. As a result, the portion of the communication groove 15 on the tip surface 14 side deforms to expand, causing the tip edge 16a of the communication groove 15 to come into contact with the inner circumferential surface 6, and both sides in the axial direction become disconnected.

[0025] The example in Figure 3 illustrates a case where the interference fit is larger compared to the example described above. In this modified example, the groove depth of the mounting groove 4A of the inner circumferential member 2 is smaller than in the example described above. That is, the dimension from the bottom of the mounting groove 4A to the inner circumferential surface 6 is smaller than in the example described above. Alternatively, the outer diameter of the inner circumferential member 2 may be made smaller than in the example described above to reduce the groove depth of the mounting groove 4A. Or, the diameter of the bottom of the mounting groove 4A may be made larger than in the example described above to reduce the groove depth of the mounting groove 4A. In this case, the diameter of the sealing member 1 may be made larger than in the example described above, in accordance with the diameter of the bottom of the mounting groove 4A. In this modified example, as shown in Figure 3(a), when the inner circumferential member 2 is stationary and in the initial state of movement, the surface 13a of the sliding contact portion 13 at the tip of the lip portion 12 is in relatively large contact with the inner circumferential surface 6. Even in this state, the side wall edges 16b, 16b and the rear edge 16c of the inner side surface 15c of the communication groove 15 are not in contact with the inner circumferential surface 6, and the spaces on both sides in the axial direction are in communication via the communication groove 15. From this state, as shown in Figure 3(b), when the inner circumferential member 2 moves, the lip portion 12 deforms so that it is pressed against the inner circumferential surface 6, similar to the above. As a result, the surface 13a of the sliding contact portion 13 of the lip portion 12 comes into larger contact with the inner circumferential surface 6, the side wall edges 16b, 16b and the rear edge 16c of the communication groove 15 come into contact with the inner circumferential surface 6, and both sides in the axial direction become disconnected.

[0026] In addition to being used in a sealing structure that seals the gap between the inner circumferential member 2 and the outer circumferential member 5, which move relatively back and forth as described above, the sealing member 1 according to this embodiment may also be used in a sealing structure that seals the gap between the inner circumferential member 2 and the outer circumferential member 5, which rotate relatively around their axis. The example described above illustrates a sealing member 1 having a base portion 10 that fits into mounting grooves 4, 4A provided on the inner circumferential member 2, but the invention is not limited to this configuration. The sealing member 1 may also have a base portion 10 that fits into mounting grooves provided on the outer circumferential member 5. In other words, the sealing member 1 may have a lip portion 12 that extends from a base portion 10 that fits into mounting grooves provided on the outer circumferential surface 6, which constitutes the first surface, toward the inner circumferential surface 3, which constitutes the second surface. In other words, the lip portion 12 may be provided on the inner circumferential side of the base portion 10.

[0027] In the example described above, the connecting groove 15 is shown as being roughly V-shaped when viewed in the longitudinal direction of the groove. However, it may also be roughly U-shaped, roughly trapezoidal, roughly semicircular, etc. Furthermore, the connecting groove 15 is not limited to being formed in an expanding manner from the groove bottom surface 15a side. In the example described above, the communication groove 15 is shown to be open at the tip surface 14, but it does not have to be open at the tip surface 14. In this case, the surface 13a of the sliding contact portion 13 may be made into a curved surface so that the tip of the lip portion 12 does not contact the second surface (inner circumferential surface 6), and the communication groove 15 may be configured to communicate the spaces on both sides in the axial direction. In this case, the groove bottom surface 15a of the communication groove 15 and the surface 13a of the sliding contact portion 13 may not be parallel, but rather the groove depth may decrease as it moves outward in the longitudinal direction of the groove. The communication groove 15 may also have various other configurations.

[0028] In the recess 17 described above, an example is shown where the dimension L2 along the extension direction of the lip portion 12 is smaller than the groove length L1 of the communication groove 15. However, any appropriate dimension that makes the tip side of the lip portion 12 more easily deformable is acceptable. For example, the dimension L2 along the extension direction of the lip portion 12 in the recess 17 may be larger than the groove length L1 of the communication groove 15. Also, the dimension along the thickness direction of the lip portion 12 in the recess 17 may be an appropriate dimension that makes the tip side of the lip portion 12 more easily deformable. For example, it may be larger than the dimension along the thickness direction of the lip portion 12 in the communication groove 15. In the example described above, a recess 17 is provided on the side opposite to the side where the communication groove 15 is provided in the radial direction at the tip of the lip portion 12. However, it is also possible to omit such a recess 17. In the example described above, the lip portion 12 is formed so that its thickness decreases towards the tip, but it may also have a uniform thickness throughout the entire extension direction, or the thickness may be reduced in the intermediate parts of the extension direction. In the example described above, the lip portion 12 is formed such that, in the radial direction, its entire tip surface 14 is located on the second surface (inner circumferential surface 6) side of the first surface (outer circumferential surface 3), but the configuration is not limited to this. The lip portion 12 may have various other configurations. [Explanation of Symbols]

[0029] 1. Sealing member 10 base 12 Lip section 13 Sliding contact part 13a surface 14 Tip surface 15 Communication groove 15a Groove bottom surface 15b Groove side wall 16 Peripheral area 16a Tip edge (periphery) 16b Side wall edge (periphery) 16c Rear edge (periphery) 17 recess 2 Inner circumference side member 3 Outer surface (first surface) 4. Mounting groove 5. Outer peripheral member 6 Inner surface (2nd surface) 7 Sealed space

Claims

1. An annular base that fits into an annular mounting groove provided to open on the inner surface of the radially opposing outer peripheral member and on the first surface of the outer peripheral surface of the inner peripheral member, An annular lip portion is provided that extends diagonally from the base toward the second surface of the inner and outer circumferential surfaces and toward the sealed space on one axial side, and slides against the second surface, A communication groove is provided in the sliding contact portion of the lip portion, and extends in the direction of extension of the lip portion, It is equipped with, The sealing member is characterized in that the communication groove is formed such that it moves from a communicating state, where the spaces on both sides in the axial direction are connected, to a non-communicating state, where the peripheral edge of the communication groove comes into contact with the second surface due to deformation of the lip portion caused by the pressure rise on the side of the sealed space.

2. In claim 1, The sealing member is characterized in that the communication groove opens at the tip surface of the lip portion, and the bottom surface of the groove is parallel to the surface of the sliding contact portion of the lip portion.

3. In claim 2, A sealing member characterized in that both groove side walls of at least the opening side portion of the tip surface of the communication groove are formed in an expanding manner from the groove bottom surface side.

4. In claim 2, A sealing member characterized in that, on the side of the tip of the lip portion opposite to the side where the communication groove is provided in the radial direction, a recess that opens on the tip surface is provided.

5. In claim 1, The sealing member is characterized in that the lip portion is formed such that its thickness decreases towards the tip.

6. In claim 1, The sealing member is characterized in that the lip portion is formed such that, in the radial direction, its entire tip surface is located on the second surface side of the first surface.

7. A sealing structure that seals the space between an outer peripheral member and an inner peripheral member, using a sealing member according to any one of claims 1 to 6, wherein the pressure in the sealed space on one side in the axial direction increases with relative axial movement, A sealing structure characterized in that the base of the sealing member is fitted into an annular mounting groove provided to open on the first surface of the radially opposing inner and outer surfaces of the outer peripheral member and the outer peripheral member, and the lip portion of the sealing member is in contact with the second surface of the inner and outer peripheral surfaces.

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