Sealing device and method for manufacturing same

Abstract

This sealing device is for sealing a tubular gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member surrounding the first member, the sealing device comprising: an annular seal lip 110 surrounding the outer peripheral surface and slidably in close contact with the outer peripheral surface; and a gripping ring that grips the outer peripheral side of the seal lip 110 and is in close contact with the inner peripheral surface. The gripping ring 120 has a U-shaped cross section and includes a surrounding part 122 that surrounds an outer peripheral surface 110b of the seal lip 110, a plate-like and annular first gripping part 124 extending inward from one end of the surrounding part 122, and a plate-like and annular second gripping part 126 extending inward from the other end of the surrounding part 122 and gripping the seal lip 110 located between the first gripping part 124 and the second gripping part 126. The surrounding part 122, the first gripping part 124, and the second gripping part 126 are formed from a single continuous plate material, and at least a part of the surrounding part 122 is formed thinner than the first gripping part 124.

Description

Sealing device and manufacturing method thereof

[0001] The present invention relates to a sealing device and a method for manufacturing the same.

[0002] A sealing device that seals a cylindrical gap between the outer peripheral surface of a first member and the inner peripheral surface of a second member surrounding the first member is known. Patent Document 1 discloses a sealing device including an annular seal lip that surrounds the outer peripheral surface of the first member and slidably contacts the outer peripheral surface of the first member, and a gripping ring that grips the outer peripheral side of the seal lip and contacts the inner peripheral surface of the second member. In this sealing device, the gripping ring has a horizontal U-shaped cross section cut along a plane including the central axis, and is made of a single continuous plate. This sealing device allows for a reduction in the number of parts.

[0003] Japanese Patent Application Laid-Open No. 2021-179241

[0004] The sealing device of Patent Document 1 has room for improvement in terms of facilitating manufacturing.

[0005] The present invention has been made in view of the above circumstances, and one exemplary purpose of an embodiment of the present invention is to provide a sealing device that can be easily manufactured.

[0006] To solve the above problems, a sealing device according to one aspect of the present invention is a sealing device that seals a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member that surrounds the first member, and includes: an annular seal lip that surrounds the outer peripheral surface and slidably contacts the outer peripheral surface; and a gripping ring that grips the outer peripheral side of the seal lip and contacts the inner peripheral surface. The gripping ring has a U-shaped cross section. The gripping ring includes: an encircling portion that surrounds the outer peripheral surface of the seal lip; a plate-shaped, annular first gripping portion that extends inward from one end of the encircling portion; and a plate-shaped, annular second gripping portion that extends inward from the other end of the encircling portion and grips the seal lip between itself and the first gripping portion. The encircling portion, the first gripping portion, and the second gripping portion are formed from a single continuous plate material, and at least a portion of the encircling portion is formed thinner than the first gripping portion.

[0007] Another aspect of the present invention is a sealing device that seals a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member that surrounds the first member, and includes an annular seal lip that surrounds the outer peripheral surface and slidably contacts the outer peripheral surface, and a gripping ring that grips the outer peripheral side of the seal lip and contacts the outer peripheral surface. The gripping ring includes an encircling portion that surrounds the outer peripheral side of the seal lip, a plate-shaped annular first gripping portion that extends inward from one end of the encircling portion, and a plate-shaped annular second gripping portion that extends inward from the other end of the encircling portion and grips the seal lip between itself and the first gripping portion. The surrounding portion, the first gripping portion, and the second gripping portion are formed from a single continuous plate material, and the axial dimension of the gripping ring is 1.5 times or less the sum of the thickness of the inner end of the first gripping portion, the thickness of the inner end of the second gripping portion, and the thickness of the seal lip, and at least a portion of the surrounding portion is formed thinner than the first gripping portion.

[0008] Yet another aspect of the present invention is a manufacturing method for a sealing device that seals a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member that surrounds the first member, the manufacturing method including: preparing an annular plate having a first gripping portion and a cylindrical portion rising from an outer peripheral end of the first gripping portion, the cylindrical portion being formed with a thin wall corresponding to at least a part of the surrounding portion; bending the cylindrical portion over the entire circumferential direction with a seal lip overlapped by the first gripping portion to form a second gripping portion and the surrounding portion; and gripping the outer peripheral portion of the seal lip with the first gripping portion and the second gripping portion.

[0009] According to the present invention, it is possible to provide a sealing device that can be easily manufactured.

[0010] Fig. 2 is a cross-sectional view of a sealing device according to an embodiment. Fig. 3 is a cross-sectional view showing a state in which the sealing device of Fig. 1 is used. Fig. 4 is an enlarged cross-sectional view showing an enlarged grip ring of Fig. 1. Fig. 5 is a view showing an example of a method for manufacturing the sealing device of Fig. 1. Fig. 6 is a view showing an example of a method for manufacturing the sealing device of Fig. 1.

[0011] The present invention will be described below based on preferred embodiments with reference to the drawings. The embodiments are illustrative and do not limit the invention, and all features and combinations described in the embodiments are not necessarily essential to the invention. The same or equivalent components, parts, and processes shown in each drawing are designated by the same reference numerals, and redundant descriptions will be omitted where appropriate.

[0012] 1 and 2 , the sealing device 100 seals a cylindrical gap 14 between an outer peripheral surface 10 a of a first member 10 and an inner peripheral surface 12 a of a second member 12 that surrounds the first member 10. The first member 10 moves relative to the second member 12. That is, the sealing device 100 seals the cylindrical gap 14 between the first member 10 and the second member 12, which move relatively. The relative movement is rotation, reciprocation, swinging, or a combination of two or more of these movements.

[0013] For example, the sealing device 100 is used to seal a cylindrical gap 14 between a first member 10, which is a shaft member, and a second member 12, which is a housing, in an exhaust gas system such as an EGR (Exhaust Gas Recirculation) system.

[0014] In this embodiment, the outer peripheral surface 10a of the first member 10 is a cylindrical surface, and the inner peripheral surface 12a of the second member 12 is a cylindrical surface. The central axis of the outer peripheral surface 10a of the first member 10 and the central axis of the inner peripheral surface 12a of the second member 12 coincide with each other. Therefore, in this embodiment, the gap 14 is a cylindrical gap. Naturally, the central axis of the gap 14 coincides with the central axes of the outer peripheral surface 10a and the inner peripheral surface 12a. Hereinafter, this coincident central axis will be referred to as the central axis C.

[0015] Hereinafter, a direction parallel to the central axis C will be referred to as the axial direction, any direction passing through the central axis C on a plane perpendicular to the central axis C will be referred to as the radial direction, the side closer to the central axis C in the radial direction will be referred to as the inner side, the side farther from the central axis C will be referred to as the outer side, and the direction along the circumference of a circle centered on the central axis C on a plane perpendicular to the central axis C will be referred to as the circumferential direction.

[0016] The sealing device 100 includes a seal lip 110 and a gripping ring 120 that grips the outer periphery of the seal lip 110 over the entire circumference.

[0017] The seal lip 110 is a disc-shaped member centered on the central axis C. The seal lip 110 is formed with a circular central hole (opening) 110a centered on the central axis C. The inner diameter of the seal lip 110, i.e., the outer diameter of the central hole 110a, is smaller than the outer diameter of the first member 10. The seal lip 110 is formed, for example, from a resin material, particularly a fluororesin material such as PTFE (polytetrafluoroethylene), with a plate thickness of, for example, 0.3 mm or more and 0.6 mm or less. Compared to elastic materials such as rubber, PTFE has excellent heat resistance, pressure resistance, and chemical resistance, and is characterized by low sliding wear.

[0018] The grip ring 120 is an annular member centered on a central axis C. The grip ring 120 is made of a metal material, for example, SUS, which has excellent corrosion resistance.

[0019] The gripping ring 120 includes an encircling portion 122, a first gripping portion 124, and a second gripping portion 126. The gripping ring 120 is formed by bending a single flat plate. That is, the encircling portion 122, the first gripping portion 124, and the second gripping portion 126 are formed from a single continuous plate material.

[0020] The surrounding portion 122 is a cylindrical portion that surrounds the outer peripheral surface 110b of the seal lip 110. The surrounding portion 122 is a portion of the gripping ring 120 that is located radially outward of the outer peripheral surface 110b of the seal lip 110. The inner peripheral surface 122a of the surrounding portion 122 may not be in contact with the outer peripheral surface of the seal lip 110, i.e., may have a larger diameter than the outer peripheral surface 110b of the seal lip 110, as in the illustrated example, or may be in contact with the outer peripheral surface 110b of the seal lip 110, as in the illustrated example. Both ends of the cylindrical surrounding portion 122 may be folded back toward the inner peripheral side. In the present embodiment, the outer peripheral surface 122b of the surrounding portion 122 preferably includes a portion 122c that is a cylindrical surface.

[0021] The first gripping portion 124 is a plate-like, annular portion that extends inward from one end of the cylindrical surrounding portion 122. The inner diameter of the first gripping portion 124 is larger than the inner diameter of the seal lip 110 and smaller than the outer diameter of the seal lip 110.

[0022] The second gripping portion 126 is a plate-shaped, annular portion that extends from the other end of the cylindrical surrounding portion 122 toward the inner periphery in parallel to the first gripping portion 124. The inner diameter of the second gripping portion 126 is larger than the inner diameter of the seal lip 110 and smaller than the outer diameter of the seal lip 110. The inner diameter of the second gripping portion 126 is not particularly limited, but is larger than the inner diameter of the first gripping portion 124.

[0023] In this embodiment, when the sealing device 100 is in use, the "one end side" is the side opposite the area to be sealed, and the "other end side" is the side of the area to be sealed.

[0024] An opposing surface 124a of the first gripping portion 124 that faces the seal lip 110 is preferably flat. An opposing surface 126a of the second gripping portion 126 that faces the seal lip 110 is preferably flat.

[0025] The first gripping portion 124 and the second gripping portion 126 sandwich and grip the outer circumferential side of the seal lip 110 between them over the entire circumference. That is, the first gripping portion 124 and the second gripping portion 126 sandwich and grip the outer circumferential side of the seal lip 110 over the entire circumference in the axial direction. The first gripping portion 124 and the second gripping portion 126 may sandwich the outer circumferential side of the seal lip 110 so as to compress it in the axial direction.

[0026] In use, the sealing device 100 is inserted into the second member 12 and fitted onto the inner circumferential surface 12a of the second member 12. More specifically, the outer circumferential surface 122b of the surrounding portion 122 of the grip ring 120 of the sealing device 100 is fitted onto the inner circumferential surface 12a of the second member 12. The outer circumferential surface 122b of the surrounding portion 122 is in close contact with the inner circumferential surface 12a of the second member 12 over the entire circumference. The first member 10 is inserted into the central hole 110a of the seal lip 110 from the side opposite the area to be sealed.

[0027] As described above, the inner diameter of the seal lip 110 is smaller than the outer diameter of the first member 10, and therefore, in use, the inner peripheral portion of the seal lip 110 is curved toward the area to be sealed. Specifically, the seal lip 110 is curved such that the surface 110c opposite the area to be sealed expands and the surface 110d opposite the area to be sealed contracts. By curving the seal lip 110 in this manner, in use, the inner peripheral side of the surface 110c opposite the area to be sealed of the seal lip 110 is in close contact with the outer peripheral surface 10a of the first member 10 over the entire circumference.

[0028] The seal lip 110 may have an inner diameter equal to the outer diameter of the first member 10, and the inner peripheral surface 110e may be in close contact with the outer peripheral surface 10a of the first member 10 over the entire circumference without being curved.

[0029] In either case, the seal lip 110 is in close contact with the outer peripheral surface 10a of the first member 10 over the entire circumference. In this state, the first member 10 is movable relative to the second member 12. In other words, the seal lip 110 is slidable relative to the first member 10.

[0030] The grip ring 120 will be described in detail with reference to FIG.

[0031] The gripping ring 120 has a cross section cut along a plane including the central axis C (not shown in FIG. 3 ) that is a sideways U-shape, i.e., a U-shape that opens toward the inner periphery. The axial dimension D of the gripping ring 120 is 1.5 times or less the combined thickness of the inner periphery end 124b of the first gripping portion 124, the inner periphery end 126b of the second gripping portion 126, and the seal lip 110. In other words, the gripping ring 120 has a relatively short axial dimension D.

[0032] The gripping ring 120 includes a central portion 130 that overlaps the outer peripheral surface 110b of the seal lip 110 when viewed radially, a first gripping portion side portion 132 that is connected to the central portion 130 and the first gripping portion 124, and a second gripping portion side portion 134 that is connected to the central portion 130 and the second gripping portion 126.

[0033] The gripping ring 120 is formed so that at least a portion of the surrounding portion 122 in the axial direction, for example, the entire circumference, is thinner than the first gripping portion 124. This allows the plate to be easily bent when the gripping ring 120 is formed by bending the plate. In other words, the gripping ring 120, and therefore the sealing device 100, can be easily manufactured.

[0034] For example, at least a portion of the central portion 130 may be formed thinner than the first gripping portion 124, for example, over the entire circumference.

[0035] For example, at least a portion of the first gripping portion side section 132 may be formed thinner than the first gripping portion 124, for example, over the entire circumference.

[0036] For example, at least a portion of the second grip portion side section 134 may be formed thinner than the first grip portion 124, for example, over the entire circumference.

[0037] Furthermore, at least a portion of any two or more of the central portion 130, the first grip portion side portion 132, and the second grip portion side portion 134 may be formed, for example, over the entire circumference, to be thinner than the first grip portion 124. For example, at least a portion of the first grip portion side portion 132 and at least a portion of the second grip portion side portion 134 may be formed, for example, over the entire circumference, to be thinner than the first grip portion 124. Furthermore, for example, the entire central portion 130 and the entire second grip portion side portion 134 may be formed, for example, over the entire circumference, to be thinner than the first grip portion 124.

[0038] Furthermore, at least a portion of the second gripping portion 126 may be formed thinner than the first gripping portion 124, for example, over the entire circumference. For example, when a thin portion of the surrounding portion 122 is continuous with the second gripping portion 126, at least a portion of the second gripping portion 126 on the surrounding portion 122 side may be formed thinner. In other words, a thin portion may be formed across the surrounding portion 122 and the second gripping portion 126. In this case, when a single plate is bent to form the gripping ring 120, the plate can be bent more easily. In other words, the gripping ring 120, and therefore the sealing device 100, can be manufactured more easily.

[0039] In the illustrated example, the entire surrounding portion 122, i.e., the entire central portion 130, the entire first gripping portion side portion 132, the entire second gripping portion side portion 134, and the entire second gripping portion 126 are formed to be thin. In this case, when bending a single plate to form the gripping ring 120, the plate can be bent more easily, making it easier to manufacture the gripping ring 120 and, ultimately, the sealing device 100. Furthermore, because the entire second gripping portion 126 is thin, the occurrence of wrinkles in the second gripping portion 126 is suppressed compared to when it is not thin.

[0040] Furthermore, the second gripping portion 126 may be formed with the same thickness throughout, or, as shown in the example shown, the inner end 126b may be formed with a greater thickness than other portions, such as the outer end 126c. In other words, the second gripping portion 126 may be formed with a thinner thickness throughout than the first gripping portion, while the inner end 126b may be formed with a relatively greater thickness. In this case, the force with which the inner circumferential side of the second gripping portion 126 presses against the seal lip 110 is stronger than when the entire second gripping portion 126 is formed with the same thin thickness, thereby more reliably sealing the gap between the second gripping portion 126 and the seal lip 110.

[0041] Next, an example of a method for manufacturing the sealing device 100 configured as above will be described.

[0042] First, refer to Figures 4(a) to 4(d). As shown in Figures 4(a) to 4(d), an annular plate 142 is formed from a flat plate 140 using a drawing press machine 200. The press machine 200 includes a die 202, a punch 204, and a blank holder 206. The die 202 is a metal mold having a cylindrical recess 202a.

[0043] As shown in FIG. 4A, a circular flat plate 140 is prepared, and the flat plate 140 is placed on the die 202 so that the central axis of the opening of the flat plate 140 coincides with the central axis of the recess 202a of the die 202.

[0044] Next, as shown in FIG. 4B, the blank holder plate 206 is lowered, and pressure is applied to the blank holder plate 206 to hold down the flat plate 140.

[0045] 4(c) and 4(d), punch 204 is pressed into recess 202a of die 202. As a result, flat plate 140 is deformed to follow the shapes of recess 202a of die 202 and punch 204, and an annular plate 142 having an L-shaped cross section is formed. Annular plate 142 has first gripping portion 124 and a tubular portion 144 rising from the outer peripheral end of first gripping portion 124.

[0046] The diameter φ1 of the recess 202a of the die 202 matches the outer diameter of the surrounding portion 122 of the gripping ring 120. The outer diameter φ2 of the punch 204 matches the inner diameter of the surrounding portion 122. The radial gap between the peripheral surface of the recess 202a of the die 202 and the outer peripheral surface of the punch 204 is thinner than the thickness of the flat plate and therefore the first gripping portion. Therefore, when the punch is pressed into the recess of the die to form the tubular portion 144, the tubular portion 144 is stretched and thinned. In other words, the tubular portion 144 is formed thinner than the first gripping portion 124.

[0047] Alternatively, a flat plate with a pre-formed thin wall portion may be prepared, in which case the cylindrical portion is not thinned in the manner shown in Figures 4(c) and 4(d).

[0048] Next, refer to Figures 5(a) to 5(d). As shown in Figure 5(a), the annular plate 142 is placed on the rotary table 210, and the seal lip 110 is placed on the first gripping portion 124 of the annular plate 142. Specifically, the seal lip 110 is placed on the first gripping portion 124 so that the central axis of the opening of the annular plate 142 and the central axis of the seal lip 110 coincide with each other. As a result, the outer peripheral portion of the seal lip 110 overlaps with the first gripping portion 124 along the entire circumference.

[0049] Next, as shown in Figure 5(b), the rotary table 210 and therefore the annular plate 142 are rotated. In this state, the oblique roller 212, whose rotation axis R1 is oriented obliquely, is brought into contact with the cylindrical portion from the outer periphery, and the oblique roller 212 is further moved in the direction of the rotation axis R1 to create a crease in the cylindrical portion 144 for bending the cylindrical portion 144. Note that, because the cylindrical portion 144 is formed to be thin, it is easy to create a crease in the cylindrical portion 144.

[0050] 5(c), while the turntable 210 and, therefore, the annular plate 142 with the crease formed in the tubular portion 144 are rotated, a vertical roller 214 with its rotation axis R2 oriented perpendicular to the mounting surface of the turntable 210 is brought into contact with the tubular portion 144, and the vertical roller 214 is further moved in the direction of the rotation axis R2 to bend the tubular portion 144. Note that, because the tubular portion 144 is formed to be thin, it can be easily bent.

[0051] 5(d), the surrounding portion 122 and the second gripping portion 126 are formed. The seal lip 110 is gripped by the first gripping portion 124 and the second gripping portion 126. In other words, the sealing device 100 is completed.

[0052] The present invention has been described above based on an embodiment. This embodiment is merely an example, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component and each treatment process, and that such modifications are also within the scope of the present invention. Such modifications will now be described.

[0053] (Variation 1) In the above embodiment, a case has been described in which the first gripping portion 124 of the gripping ring 120 is located on the side opposite the area to be sealed and the second gripping portion 126 is located on the side opposite the area to be sealed when the sealing device 100 is in use, but the first gripping portion 124 may be located on the side opposite the area to be sealed and the second gripping portion 126 may be located on the side opposite the area to be sealed. In other words, the gripping portion located on the side opposite the area to be sealed may be formed with a thin wall.

[0054] (Variation 2) In the embodiment, the case where the outer peripheral surface 10a of the first member 10 is cylindrical has been described, but the shape of the outer peripheral surface 10a of the first member 10 is not particularly limited as long as the seal lip 110 can be in close contact with the outer peripheral surface 10a of the first member 10 over the entire circumference. For example, the outer peripheral surface 10a of the first member 10 may be elliptical cylindrical. In this case, the central hole 110a of the seal lip 110 may be elliptical.

[0055] (Variation 3) In the embodiment, the case where the inner circumferential surface 12a of the second member 12 is cylindrical has been described, but the shape of the inner circumferential surface 12a of the second member 12 is not particularly limited as long as the outer circumferential surface 122b of the surrounding portion 122 of the grip ring 120 can be in close contact with the inner circumferential surface 12a of the second member 12 over the entire circumference. For example, the inner circumferential surface 12a of the second member 12 may be an elliptical cylindrical shape.

[0056] The above-described embodiment can be generalized to provide the following aspects.

[0057] [Aspect 1] A sealing device that seals a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member that surrounds the first member, the sealing device comprising: an annular seal lip that surrounds the outer peripheral surface and is in slidable close contact with the outer peripheral surface; and a gripping ring that grips the outer peripheral side of the seal lip and is in close contact with the inner peripheral surface, the gripping ring having a U-shaped cross section and including: an encircling portion that surrounds the outer peripheral surface of the seal lip; a plate-shaped annular first gripping portion that extends inward from one end of the encircling portion; and a plate-shaped annular second gripping portion that extends inward from the other end of the encircling portion and grips the seal lip between itself and the first gripping portion, the encircling portion, the first gripping portion, and the second gripping portion being configured from a single continuous plate material, and at least a portion of the encircling portion being formed thinner than the first gripping portion.

[0058] [Aspect 2] A sealing device that seals a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member that surrounds the first member, the sealing device comprising: an annular seal lip that surrounds the outer peripheral surface and slidably contacts the outer peripheral surface; a gripping ring that grips an outer peripheral side of the seal lip and contacts the outer peripheral surface; the gripping ring includes an encircling portion that surrounds an outer circumferential side of the seal lip, a plate-shaped annular first gripping portion that extends inward from one end of the encircling portion, and a plate-shaped annular second gripping portion that extends inward from the other end of the encircling portion and grips the seal lip between itself and the first gripping portion, the encircling portion, the first gripping portion, and the second gripping portion being configured from a single continuous plate material, the axial dimension of the gripping ring is 1.5 times or less the sum of the thickness of an inner circumferential end of the first gripping portion, the thickness of an inner circumferential end of the second gripping portion, and a thickness of the seal lip, and at least a portion of the encircling portion is formed to be thinner than the first gripping portion.

[0059] [Aspect 3] The sealing device according to aspect 1 or 2, wherein the at least a portion of the surrounding portion is continuous with the second gripping portion, and the second gripping portion is also formed to have a thin wall.

[0060] [Aspect 4] The sealing device according to Aspect 3, wherein the second gripping portion is formed so that an end portion on an inner circumferential side is thicker than an end portion on an outer circumferential side.

[0061] [Aspect 5] A method for manufacturing a sealing device according to any one of Aspects 1 to 4, comprising: preparing an annular plate having the first gripping portion and a tubular portion rising from an outer peripheral end of the first gripping portion, the annular plate having a thin-walled portion corresponding to at least a portion of the surrounding portion; bending the tubular portion over the entire circumferential direction with the seal lip overlapped on the first gripping portion, thereby forming the second gripping portion and the surrounding portion; and gripping the outer peripheral portion of the seal lip with the first gripping portion and the second gripping portion.

[0062] [Aspect 6] The method for manufacturing a sealing device according to Aspect 5, wherein preparing the annular plate includes bending a flat plate having an opening to form the annular plate having the first gripping portion and the tubular portion, and forming the annular plate includes forming a thin-walled portion corresponding to at least the portion.

[0063] The present invention can be used for a sealing device and a manufacturing method thereof.

[0064] Reference Signs List 10 first member, 10a outer peripheral surface, 12 second member, 12a inner peripheral surface, 14 gap, 100 sealing device, 110 seal lip, 110b outer peripheral surface 110, 120 grip ring, 122 surrounding part, 124 first grip part, 126 second grip part.

Claims

1. A sealing device for sealing a cylindrical gap between the outer peripheral surface of a first member and the inner peripheral surface of a second member surrounding the first member, comprising: an annular seal lip that surrounds the outer peripheral surface and is in close, slidable contact with the outer peripheral surface; and a gripping ring that grips the outer peripheral side of the seal lip and is in close contact with the inner peripheral surface, wherein the gripping ring has a U-shaped cross section and includes: an enclosing portion that surrounds the outer peripheral surface of the seal lip; a plate-shaped, annular first gripping portion that extends inward from one end of the enclosing portion; and a plate-shaped, annular second gripping portion that extends inward from the other end of the enclosing portion and grips the seal lip between itself and the first gripping portion, wherein the enclosing portion, the first gripping portion, and the second gripping portion are formed from a single continuous plate material, and at least a portion of the enclosing portion is formed to be thinner than the first gripping portion.

2. A sealing device for sealing a cylindrical gap between an outer peripheral surface of a first member and an inner peripheral surface of a second member surrounding the first member, comprising: an annular seal lip surrounding the outer peripheral surface and slidably contacting the outer peripheral surface; and a gripping ring in close contact with the outer peripheral surface and gripping the outer peripheral side of the seal lip, wherein the gripping ring includes: an encircling portion surrounding the outer peripheral side of the seal lip; a plate-shaped annular first gripping portion extending inward from one end of the encircling portion; and a plate-shaped annular second gripping portion extending inward from the other end of the encircling portion and gripping the seal lip between itself and the first gripping portion, wherein the encircling portion, the first gripping portion, and the second gripping portion are formed from a single continuous plate material, and the axial dimension of the gripping ring is 1.5 times or less the sum of the thickness of the inner peripheral end of the first gripping portion, the thickness of the inner peripheral end of the second gripping portion, and the thickness of the seal lip, A sealing device, wherein at least a portion of the surrounding portion is formed to be thinner than the first gripping portion.

3. A sealing device according to claim 1 or 2, wherein at least a portion of the surrounding portion is continuous with the second gripping portion, and the second gripping portion is also formed to have a thin wall.

4. A sealing device according to claim 3, wherein the second gripping portion is formed so that the inner end is thicker than the outer end.

5. A method for manufacturing a sealing device as set forth in claim 1 or 2, comprising: preparing a single annular plate having the first gripping portion and a tubular portion rising from the outer peripheral end of the first gripping portion, the single annular plate having a thin-walled portion corresponding to at least a portion of the surrounding portion; and forming the second gripping portion and the surrounding portion by bending the tubular portion over the entire circumferential direction with the seal lip overlapping the first gripping portion, and gripping the outer peripheral portion of the seal lip with the first gripping portion and the second gripping portion.

6. A method for manufacturing a sealing device as described in claim 5, wherein preparing the annular plate includes forming the annular plate having the first gripping portion and the tubular portion by bending a flat plate having an opening, and forming the annular plate to form a thin-walled portion corresponding to at least the part.

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