gasket

Abstract

To provide a gasket that can be easily assembled into an annular gap. [Solution] A gasket (1) is provided that is inserted from one end of a shaft member (200) into an annular gap (G) between a housing (100) and the housing, at least a portion of which is inserted into the housing, toward the other end of the shaft member. The gasket includes a cylindrical main body (10) that is inserted into the housing and fixed to it, and a sealing portion (20) that extends from an inner circumferential surface (14) of the main body and abuts against an outer circumferential surface (201a) of the shaft member. The sealing portion is made of a ridge (20) that extends circumferentially at a midpoint in the insertion direction on the inner circumferential surface of the main body and protrudes radially inward.

Description

[Technical field]

[0001] The present invention relates to a gasket for sealing an annular gap between a housing and a shaft member inserted into the housing. [Background technology]

[0002] Gaskets are installed in machines in various fields such as automobiles as sealing parts that seal the gap between two stationary members that do not move relative to each other. For example, Patent Document 1 discloses a gasket inserted into an annular gap between a second member (hereinafter referred to as a housing) and a first member (hereinafter referred to as a shaft member) inserted into the housing. Such a gasket exerts a sealing function by closely contacting the inner peripheral surface of the housing where the shaft member is inserted and the outer peripheral surface of the shaft member, and is also called an inner / outer diameter seal. The gasket disclosed in Patent Document 1 has a cylindrical gasket main body (hereinafter referred to as a main body) that is inserted into the housing, and an annular lip (hereinafter referred to as a seal portion) that extends from the inner peripheral surface of the main body and contacts the outer peripheral surface of the shaft member. This seal portion has a base end that connects to the inner peripheral surface of the main body and a tip end that contacts the outer peripheral surface of the shaft member, and is formed in a tapered tube shape that is reduced in diameter from the base end toward the tip end. This seal portion has an inner inclined surface and an outer inclined surface that are inclined in approximately the same direction relative to the outer peripheral surface of the shaft member. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-132078 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, the gasket of the inner and outer diameter seal type disclosed in Patent Document 1 is configured as a so-called lip type in which the seal portion that contacts the outer peripheral surface of the shaft member is formed into a tapered cylindrical shape as a whole, and has a structure that is easily deformed when inserted into the annular gap between the housing and the shaft member. Therefore, when this gasket is inserted into the annular gap and assembled (mounted), for example, the seal portion may be deformed into an unintended shape, and as a result, the seal portion (for example, the top of the seal portion) may not be positioned on the intended seal surface and may fall off from the seal surface. As a result, for example, if the gasket after assembly is deformed into an unintended shape, the worker or the like must redo the assembly work. For this reason, the gasket disclosed in Patent Document 1 may require some ingenuity to prevent the seal portion from falling off from the intended seal surface during the assembly work into the annular gap.

[0005] SUMMARY OF THE PRESENT EMBODIMENTS An object of the present invention is to provide a gasket that can be easily assembled into an annular gap. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a gasket that is inserted from one end side to the other end side of the shaft member into an annular gap between a housing and a shaft member at least a portion of which is inserted into the housing. The gasket includes a cylindrical main body that is inserted into the housing and fixed to the housing, and a seal portion that extends from an inner peripheral surface of the main body and abuts against an outer peripheral surface of the shaft member. The seal portion is made of a ridge that extends circumferentially at a middle portion of the inner peripheral surface of the main body in the insertion direction and protrudes radially inward. Effect of the Invention

[0007] According to one aspect of the present invention, it is possible to provide a gasket that can be easily assembled into an annular gap. [Brief description of the drawings]

[0008] [Figure 1] 1 is a cross-sectional view of a gasket according to an embodiment of the present invention. [Diagram 2] FIG. 2 is a partial cross-sectional view of the gasket. [Diagram 3] 4A to 4C are conceptual diagrams for explaining the state before and after assembly of the gasket. [Figure 4] FIG. 2 is a partial cross-sectional view of a reference gasket (reference gasket) for the above gasket. [Diagram 5] FIG. 11 is a partial cross-sectional view illustrating a modified example of the gasket. [Figure 6] FIG. 11 is a partial cross-sectional view illustrating another modified example of the gasket. [Figure 7] FIG. 11 is a partial cross-sectional view illustrating still another modified example of the gasket. [Figure 8] 8 is a partial cross-sectional view for illustrating a gasket having both the features of the modified example in FIG. 6 and the features of the modified example in FIG. 7. FIG. [Figure 9] FIG. 4 is a cross-sectional view illustrating a gasket having a groove. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a cross-sectional view of a gasket 1 in this embodiment, and Fig. 2 is a partially enlarged cross-sectional view of the gasket 1. In Fig. 1 and Fig. 2, a part of a machine to which the gasket 1 is to be attached is indicated by a two-dot chain line, and for the sake of simplicity, the gasket 1 is shown in a state before being attached (i.e., before being elastically deformed).

[0010] [Gasket overview and installation targets] The gasket 1 is used in various machines such as automobiles, motorcycles, and general industrial machines to be mounted in an annular gap G between two stationary members (100, 200) that do not move relative to each other, and to prevent the outflow of fluids from the machines. The two members are a housing 100 and a shaft member 200. For example, the housing 100 is formed with a shaft hole 101 having a circular cross section, and a cylindrical shaft member 200 is inserted into the shaft hole 101. An example of a machine to which the gasket 1 is mounted is an oil pump for a CVT (Continuously Variable Transmission) of an automobile. This oil pump has a housing 100 and a shaft member 200, and an annular gap G is provided between the shaft hole 101 and the shaft member 200. The housing 100 and the shaft member 200 are stationary and do not move relative to each other in the extension direction of the axis X of the shaft member 200 and the rotation direction about the axis X.

[0011] In this way, the gasket 1 is inserted into the annular gap G between the housing 100 and the shaft member 200 at least a portion of which is inserted into the housing 100, and is a so-called inner / outer diameter seal type sealing component. The gasket 1 is inserted into the annular gap G and attached to the machine, thereby defining an internal space S1 of the machine. This internal space S1 communicates with a region in which a fluid (oil in this embodiment) to be sealed by the gasket 1 exists, and is configured such that communication with the atmospheric region S2 is blocked by the gasket 1. The pressure in the internal space S1 is higher than the pressure in the atmospheric region S2 during operation of the CVT, for example.

[0012] 1 shows a portion of the housing 100 including an opening on one end side of the shaft hole 101, and one end of the shaft hole 101 opens to one end surface 102 of the housing 100. In this embodiment, one end of the shaft member 200 is located in the portion on the one end side of the shaft hole 101 (i.e., the portion of the shaft hole 101 on the one end surface 102 side of the housing 100), and the shaft member 200 is inserted into the shaft hole 101 with its axis X approximately aligned with the center of the shaft hole 101. Although not particularly limited, in this embodiment, one end of the shaft member 200 has a small diameter portion 201 and a large diameter portion 202 located on the other end side of the shaft member 200 from the small diameter portion 201 and having an outer diameter larger than the outer diameter of the small diameter portion 201, and is formed in a stepped shape. The tip surface of the small diameter portion 201 of the shaft member 200 (i.e., one end surface of the shaft member 200) is located slightly closer to the internal space S1 side than the one end surface 102 of the housing 100. The outer diameter of the large diameter portion 202 of the shaft member 200 is set to be slightly smaller than the inner diameter of the shaft hole 101 .

[0013] In this embodiment, an annular gap G between the housing 100 and the shaft member 200 is formed between a portion of the inner peripheral surface of the shaft hole 101 of the housing 100 on the one end face 102 side and an outer peripheral surface 201a of the small diameter portion 201 at one end of the shaft member 200. The gasket 1 is inserted into this annular gap G from one end side of the shaft member 200 toward the other end side. That is, the insertion direction V1 of the gasket 1 into the annular gap G is parallel to the axis X of the shaft member 200. The end faces of the gasket 1 on the tip side in the insertion direction V1 (the tip face 11 of the main body 10 and the end face 32a of the inward flange portion 32 of the reinforcing ring 30 described later) face the annular end face 203 on the small diameter portion 201 side of the large diameter portion 202 of the shaft member 200, and the end face of the gasket 1 on the rear side in the insertion direction V1 (the rear end face 12 of the main body 10 described later) faces the opposite side to the annular end face 203. Specifically, in this embodiment, the gasket 1 is inserted into the housing 100 through an insertion opening formed of an opening on one end side of the axial hole 101 in one end face 102 of the housing 100. Although not particularly limited, more specifically, the gasket 1 is inserted from the insertion opening formed of an opening on one end side of the axial hole 101 in one end face 102 of the housing 100, and then, in this state, the small diameter portion 201 of the shaft member 200 is inserted into the gasket 1 from the tip side in the insertion direction V1 of the gasket 1 (the tip face 11 side of the main body portion 10 and the end face 32a side of the inward flange portion 32 of the reinforcing ring 30, which will be described later). As a result, the gasket 1 is in a state of being inserted into the annular gap G. In this embodiment, the insertion direction V1 of the gasket 1 and the insertion direction V2 of the shaft member 200 are opposite to each other. In other words, the gasket 1 is inserted into the axial hole 101 of the housing 100 from the atmosphere side, and the shaft member 200 is inserted into the axial hole 101 of the housing 100 from the machine interior side.

[0014] [Outline of gasket structure] The gasket 1 includes a cylindrical main body 10 and a seal portion 20. The main body 10 and the seal portion 20 are integrally molded and made of an elastic material. The elastic material used is a material such as rubber or a thermoplastic elastomer.

[0015] The main body 10 is a portion that is inserted into the housing 100 and fixed to the housing 100, and is formed in a generally cylindrical shape.

[0016] The tip end face 11, which is the tip end face of the main body 10 in the insertion direction V1 (in other words, the end face that is inserted first into the annular gap G), and the rear end face 12, which is the rear end face of the main body 10 in the insertion direction V1, are parallel to each other and extend in a direction perpendicular to the axis X.

[0017] The tip surface 11 of the main body 10 faces the annular end surface 203 of the large diameter portion 202 of the shaft member 200, and is formed as a flat annular surface. In this embodiment, the insertion depth of the gasket 1 into the annular gap G (for example, the distance in the extension direction of the axis X between one end surface 102 of the housing 100 and the tip surface 11 of the main body 10) is set so that a gap is formed between the tip surface 11 of the main body 10 and the annular end surface 203 of the large diameter portion 202. The above-mentioned internal space S1 is defined by the tip surface 11, the annular end surface 203, the inner peripheral surface of the shaft hole 101, and the outer peripheral surface 201a of the small diameter portion 201 of the shaft member 200.

[0018] The rear end surface 12 of the main body 10 faces the opposite side to the annular end surface 203, and is formed as a flat annular surface.

[0019] The outer peripheral surface 13 of the main body 10 is a cylindrical surface extending parallel to the axis X, and the outer diameter of the main body 10 is set to be slightly larger than the inner diameter of the axial hole 101. When the gasket 1 is inserted into the annular gap G, the main body 10 elastically deforms and the outer peripheral surface 13 comes into close contact with the inner peripheral surface of the axial hole 101. As a result, the main body 10 is fixed to the housing 100.

[0020] As described below, a seal portion 20 is protrudingly provided on the inner circumferential surface 14 of the main body 10. The inner diameter of the inner circumferential surface 14 of the main body 10 excluding the protruding region of the seal portion 20 is set to be larger than the outer diameter of a small diameter portion 201 of the shaft member 200.

[0021] The seal portion 20 is a portion that extends from the inner peripheral surface 14 of the main body portion 10 and abuts against the outer peripheral surface 201a of the shaft member 200 (the small diameter portion 201 in this embodiment). In other words, the outer peripheral surface 201a of the shaft member 200 is the seal surface. The formation position and shape of the seal portion 20 will be described in detail later.

[0022] With the gasket 1 inserted into the annular gap G, the seal portion 20 elastically deforms, and a portion including its tip portion (top portion 21 of the seal portion 20 described below) comes into close contact with the outer circumferential surface 201a of the small diameter portion 201, and the outer circumferential surface 13 of the main body portion 10 comes into close contact with the inner circumferential surface of the shaft hole 101, as described above. In this manner, a so-called inner / outer diameter seal type gasket 1 that seals the annular gap G between the inner circumferential surface of the shaft hole 101 of the housing 100 (in other words, the inner circumferential surface of the housing 100) and the outer circumferential surface 201a of the small diameter portion 201 of the shaft member 200 is configured.

[0023] In this embodiment, a reinforcing ring 30 is embedded inside the integrally molded product of the main body 10 and the seal portion 20. The reinforcing ring 30 is a member that mainly reinforces and supports the main body 10, and is located inside the main body 10. In other words, the main body 10 extends roughly along the reinforcing ring 30 and is attached by bonding to the surface of the reinforcing ring 30. The reinforcing ring 30 is made of, for example, a metal material, and is formed by press working. As the metal material, a predetermined material selected from a group of plate-shaped materials such as stainless steel, SPCC, and SPHC is used.

[0024] The reinforcing ring 30 has, for example, a generally L-shaped cross section and is molded into an annular shape about the axis X. The reinforcing ring 30 includes a cylindrical portion 31 and an inward flange portion 32, and these portions (31, 32) are molded integrally.

[0025] The cylindrical portion 31 is formed in a cylindrical shape and is located between the outer peripheral surface 13 and the inner peripheral surface 14 of the main body portion 10, and between the tip surface 11 and the outer end surface portion 12a of the rear end surface 12 of the main body portion 10. More specifically, the cylindrical portion 31 is provided at a position within the main body portion 10 closer to the outer peripheral surface 13.

[0026] The inward flange portion 32 is a flange-shaped (annular) portion extending generally radially inward from an end of the cylindrical portion 31 on the tip surface 11 side of the main body portion 10 to just before the inner circumferential surface 14 of the main body portion 10. In this embodiment, an end face 32a of the inward flange portion 32 on the tip surface 11 side of the main body portion 10 in the thickness direction is exposed to, for example, the internal space S1. The end face 32a of the inward flange portion 32 cooperates with the tip surface 11 of the main body portion 10 to form an end face on the tip side in the insertion direction V1 of the gasket 1. The end face 32a of the flange portion 32 on the tip surface 11 side does not have to be exposed to the internal space S1.

[0027] [Detailed structure of gasket] Next, the detailed structure of the gasket 1 in this embodiment will be described.

[0028] The seal portion 20 is made of a protrusion that extends circumferentially at a central portion in the insertion direction V1 on the inner peripheral surface 14 of the main body portion 10 and protrudes radially inward. A "protrusion" is a solid part that protrudes from a flat surface and extends in an elongated manner, and is known as a bead. In other words, the bead-type seal portion 20 made of a protrusion has a shape that is completely different from the conventional seal portion of the so-called lip type formed in a tapered cylindrical shape.

[0029] Specifically, the seal portion 20 includes an apex 21, a first inclined surface 22, and a second inclined surface 23, and is formed into an annular shape as a whole. In this embodiment, the seal portion 20 has a generally mountain-shaped cross section with the apex 21 on the radially inner side, and extends elongatedly over the entire circumferential direction (around the axis X) of the main body 10. The inner diameter of the seal portion 20 is set smaller than the outer diameter of the small diameter portion 201 of the shaft member 200 so that the gasket 1 elastically deforms with a predetermined tightening margin.

[0030] The apex 21 is a portion that comes into contact with the outer peripheral surface 201a of the small diameter portion 201 of the shaft member 200, and is also the top portion of the raised mountain. In this embodiment, the apex 21 is smoothly curved, and smoothly connects between the first inclined surface 22 and the second inclined surface 23.

[0031] The first inclined surface 22 is a slope on the tip surface 11 side of the main body 10 in the seal part 20 having a generally mountain-shaped cross section (i.e., the tip side in the insertion direction V1 of the seal part 20). In other words, the first inclined surface 22 is inclined so as to move away from the apex 21 toward the tip surface 11 side in the radial direction relative to the outer circumferential surface 201a of the small diameter part 201 of the shaft member 200.

[0032] The second inclined surface 23 is a slope on the rear end surface 12 side of the main body portion 10 in the seal portion 20 (i.e., the rear side in the insertion direction V1 of the seal portion 20). In other words, the second inclined surface 23 is inclined so as to move away from the outer circumferential surface 201a of the small diameter portion 201 in the radial direction from the apex 21 toward the rear end surface 12 side.

[0033] Thus, the seal portion 20 has a solid, generally mountain-shaped cross section. More specifically, the protruding seal portion 20 has a solid cross section with inclined surfaces (first inclined surface 22 and second inclined surface 23) that extend on both sides of the apex 21 in the extension direction of the axis X, and has a predetermined width in the extension direction of the axis X with the apex 21 as the center. Therefore, the protruding seal portion 20 has a relatively stable shape and a structure that is supported relatively stably by the main body portion 10, compared to conventional lip-type seal portions that are prone to elastic deformation and are unstable.

[0034] In this embodiment, the rear inner peripheral surface portion 14a, which is a portion of the inner peripheral surface 14 of the main body portion 10 that is rearward (toward the rear end surface 12) from the seal portion 20 in the insertion direction V1, is located radially inward from the front inner peripheral surface portion 14b, which is a portion of the inner peripheral surface 14 of the main body portion 10 that is forward (toward the tip surface 11) from the seal portion 20 in the insertion direction V1. That is, the inner diameter of the rear inner peripheral surface portion 14a is smaller than the inner diameter of the front inner peripheral surface portion 14b. In this embodiment, the rear inner peripheral surface portion 14a and the front inner peripheral surface portion 14b extend parallel to each other and are cylindrical surfaces that extend parallel to the outer peripheral surface 201a of the shaft member 200 (small diameter portion 201). The rear inner peripheral surface portion 14a and the apex portion 21 are connected by the second inclined surface 23, and the apex portion 21 and the front inner peripheral surface portion 14b are connected by the first inclined surface 22. The connecting portion between rear inner circumferential surface portion 14a and second inclined surface 23 is smoothly curved, and the connecting portion between front inner circumferential surface portion 14b and first inclined surface 22 is also smoothly curved.

[0035] Next, the state when the gasket 1 is inserted into the annular gap G and assembled will be described with reference to Fig. 3. Fig. 3 is a conceptual diagram for explaining the elastic deformation of the gasket 1, Fig. 3(a) shows the state before the gasket 1 is assembled (before installation), and Fig. 3(b) shows the state after the gasket 1 is assembled (after installation). In the state shown in Fig. 3(b), the pressure in the internal space S1 is assumed to be approximately the same as the pressure in the atmospheric region S2. In addition, to simplify the drawing, the reinforcing ring 30 is omitted.

[0036] In order to insert and assemble the gasket 1 into the axial hole 101 of the housing 100, an operator or the like places the tip surface 11 of the body 10 of the gasket 1 opposite to the annular end surface 203 of the shaft member 200. At this time, the tip surface 11 of the body 10 of the gasket 1 is located near an insertion port formed by an opening on one end side of the axial hole 101 in one end surface 102 of the housing 100. In this state, the gasket 1 is pressed from one end side (upper side in the figure) of the shaft member 200 toward the other end side (lower side in the figure) by a jig not shown. As a result, the gasket 1 is inserted into the axial hole 101 of the housing 100 in an insertion direction V1 from one end side to the other end side of the shaft member 200 as shown by the outline arrow, as in the gasket 1 shown by the solid line in FIG. 3(a).

[0037] When inserting into the axial hole 101, the portion of the gasket 1 on the tip surface 11 side of the body 10 is inserted (pushed in) first. At this time, the body 10 begins to elastically deform into a shape that matches the inner circumferential surface of the axial hole 101, and the outer circumferential surface 13 of the body 10 slides along the inner circumferential surface of the axial hole 101. Then, the gasket 1 is finally inserted to a predetermined insertion depth determined by the jig. Meanwhile, the inner circumferential surface 14 (specifically, the front inner circumferential surface portion 14b) of the body 10 is not in contact with the outer circumferential surface 201a of the shaft member 200.

[0038] In this embodiment, after the gasket 1 is inserted to a predetermined insertion depth as shown in FIG. 3(a), the shaft member 200 is pressed by a jig (not shown) in an insertion direction V2 opposite to the insertion direction V1 of the gasket 1 as shown by a two-dot chain line and begins to be inserted. When the shaft member 200 is further inserted, the R-shaped chamfered corner on the tip end surface side of the small diameter portion 201 abuts against the first inclined surface 22 of the seal portion 20 as shown by a dashed line in FIG. 3(a). Then, when the shaft member 200 is further inserted from the state shown by the dashed line in FIG. 3(a), the seal portion 20 of the gasket 1 begins to elastically deform. More specifically, during this insertion process, the position of the contact point C between the first inclined surface 22 of the seal portion 20 and the small diameter portion 201 gradually approaches the apex 21 side. As a result, the more the shaft member 200 is inserted, the more the clamping margin (compression amount) of the seal portion 20 in the radial outward direction increases, and the seal portion 20 is gradually crushed radially outward and pressed so as to be distorted toward the rear end face 12 side (rear side in the insertion direction V1), and the portion including the seal portion 20 is elastically deformed flat. The clamping margin in the radial outward direction of the seal portion 20 increases until the top 21 of the seal portion 20 reaches the position of the outer circumferential surface 201a of the small diameter portion 201. After the top 21 of the seal portion 20 reaches the position of the outer circumferential surface 201a of the small diameter portion 201 (the position of the seal surface), the shaft member 200 is inserted further deeply. Then, as shown in FIG. 3(b), the shaft member 200 is finally inserted to a position determined by the jig. This completes the assembly of the gasket 1 into the annular gap G. During the process of elastic deformation of the sealing portion 20, the sealing portion 20 of the gasket 1 is compressed generally radially outward and elastically deformed flat, similar to a so-called O-ring, and the sealing portion 20 is in close contact with the outer peripheral surface 201a of the shaft member 200 in approximately the intended position, range (sealing surface) and shape.

[0039] Furthermore, during the process of assembling the gasket 1 (specifically, during the process of inserting the shaft member 200), the magnitude of the insertion load required for inserting the shaft member 200 gradually increases from the initial stage of insertion, reaches a predetermined maximum insertion load, and then gradually decreases to a predetermined intermediate value. After the magnitude of the insertion load required for insertion has decreased to the predetermined intermediate value, even if the insertion depth increases, the magnitude of the insertion load required for insertion does not change and is fixed at approximately the intermediate value.

[0040] According to the gasket 1 of this embodiment, the seal portion 20 is a so-called bead type consisting of a protrusion, and therefore has a structure that is relatively stable in shape and relatively stably supported by the main body 10, compared with a conventional lip-type seal portion that is easily elastically deformed and unstable. Therefore, in the process of elastic deformation of the seal portion 20, the seal portion 20 adheres to the outer peripheral surface 201a of the shaft member 200 in a substantially intended position, range (seal surface) and shape. Therefore, the top 21 of the seal portion 20 reliably abuts against the intended seal surface (i.e., the outer peripheral surface 201a of the shaft member 200), and as a result, the top 21 of the seal portion 20 is reliably prevented from falling off the seal surface. In addition, the rework of the assembly work that may occur with a gasket having a conventional lip-type seal portion is reduced or eliminated, and the man-hours of the assembly work can be reduced. In this way, a gasket 1 that can be easily assembled into the annular gap G is provided.

[0041] In this embodiment, the reinforcing ring 30 is embedded in the main body 10. This provides stable support for the main body 10, which in turn provides stable support for the seal portion 20 and stabilizes the elastic deformation of the seal portion 20. This more reliably prevents the top 21 of the seal portion 20 from falling off the seal surface, effectively reducing the number of steps required for assembly.

[0042] Here, FIG. 4 is a partial cross-sectional view of a reference gasket Z for comparison with the gasket 1 of this embodiment. In the reference gasket Z, only the shape of the seal portion 20' is different from the seal portion 20 of the gasket 1. In the reference gasket Z, the seal portion 20' is a tapered cylindrical lip type as in the conventional gasket. In addition, when the insertion direction V1 of the gasket Z and the insertion direction V2 of the shaft member 200 are opposite to each other as in this embodiment, in consideration of the insertion of the shaft member 200 when assembling this reference gasket Z, it is necessary to arrange the gasket Z so that the tip of the tapered cylindrical seal portion 20' faces the tip side of the insertion direction V2 of the shaft member 200, that is, the upper side in FIG. 4. As a result, when the pressure in the internal space S1 becomes higher than the pressure in the atmospheric region S2 during the operation of the CVT, the entire seal portion 20 of the reference gasket Z may be deformed in a direction away from the outer peripheral surface 201a of the shaft member 200 (in the direction indicated by the dotted arrow in the figure) due to the pressure in the internal space S1. If this deformation progresses excessively and the tip of the seal portion 20 is completely separated from the outer peripheral surface 201a, the fluid to be sealed in the internal space S1 may leak out by blowing through to the atmospheric region S2. In other words, when a lip-type seal portion 20' is adopted, there is a vertical directionality when assembling the gasket, and the assembling direction (insertion direction) is restricted, and as a result, the above-mentioned blow-through problem may occur. In this regard, since the bead-type seal portion 20 is adopted in the gasket 1 of this embodiment, there is basically no vertical directionality when assembling, and the elastic deformation caused by the action of a force in the extension direction of the axis X (i.e., the pressure in the internal space S1) is very small. As a result, according to the gasket 1 of the present embodiment, it is possible to effectively prevent the above-mentioned blow-by phenomenon caused by the pressure in the internal space S1 from occurring.

[0043] [Variations] In this embodiment, the apex 21 of the seal portion 20 is a curved surface, but is not limited thereto. For example, although not shown, the apex 21 of the seal portion 20 may be a flat surface extending parallel to the outer circumferential surface 201a of the shaft member 200. This ensures that the width in the axial direction X of the region of the seal portion 20 that contacts the outer circumferential surface 201a of the shaft member 200 (i.e., the seal width) is sufficiently large, thereby improving the seal performance. Moreover, by adjusting this seal width, the seal performance and the maximum insertion load can be easily fine-tuned.

[0044] Here, since the seal portion 20 of the gasket 1 is a ridge (i.e., a bead type) whose shape is relatively stable, the maximum insertion load for inserting the gasket 1 into the annular gap G may be higher than the maximum insertion load for the lip type, as compared with a conventional lip-type seal portion 20. In regard to this point, the gasket 1 according to the modified example shown in Figs. 5 to 9 below is devised as described below in detail, that is, a weak point with low rigidity is provided in the rear part of the main body portion 10 in the insertion direction V1.

[0045] Specifically, in the gasket 1 of the modified example shown in FIG. 5, the rear inner peripheral surface portion 14a on the inner peripheral surface 14 of the main body portion 10 is located radially outward relative to the front inner peripheral surface portion 14b on the inner peripheral surface 14 of the main body portion 10, and the rear inner peripheral surface portion 14a is formed as a large-diameter conical surface and is not parallel to the front inner peripheral surface portion 14b. Thus, in the gasket 1 shown in FIG. 5, the rear side portion of the main body portion 10 in the insertion direction V1 is greatly recessed radially outward, and this portion functions as a weak point portion. In other words, this greatly recessed portion has the function of reducing the maximum insertion load for inserting the gasket 1 into the annular gap G. In addition, in FIG. 5, the second inclined surface 23 is bent halfway, but this is not limited to this, and it may extend linearly as a whole. And, as shown in FIG. 6, the top portion 21 of the seal portion 20 may be formed of a flat surface that extends parallel to the outer peripheral surface 201a of the shaft member 200. This can improve the sealing performance.

[0046] 5 and 6, in the gasket 1 of the modified example shown in Fig. 7, the rear inner circumferential surface portion 14a on the inner circumferential surface 14 of the main body portion 10 is located radially outward from the front inner circumferential surface portion 14b on the inner circumferential surface 14 of the main body portion 10. In this gasket 1, the rear inner circumferential surface portion 14a and the front inner circumferential surface portion 14b extend parallel to each other and are parallel to the outer circumferential surface 201a of the shaft member 200. In other words, in the gasket 1 shown in Fig. 7, the rear portion of the main body portion 10 in the insertion direction V1 is significantly recessed radially outward, and the rear inner circumferential surface portion 14a is formed as a large-diameter cylindrical surface, thereby providing a weak point portion with low rigidity in the rear portion of the main body portion 10 in the insertion direction V1.

[0047] In addition, the gasket 1 of the modified example shown in FIG. 8 has both the features of the modified example shown in FIG. 6 and the features of the modified example shown in FIG. 7. That is, in the gasket 1 of FIG. 8, the top 21 of the seal portion 20 extends parallel to the outer circumferential surface 201a of the shaft member 200 and is a flat surface, as in FIG. 6. Furthermore, in the gasket 1 of FIG. 8, the rear inner circumferential surface portion 14a and the front inner circumferential surface portion 14b extend parallel to each other and are cylindrical surfaces parallel to the outer circumferential surface 201a of the shaft member 200, as in FIG. 7, and the rear inner circumferential surface portion 14a has a relatively larger diameter than the front inner circumferential surface portion 14b. In this embodiment, the top 21 of the seal portion 20 formed of a flat surface improves the sealing performance, and the rear inner circumferential surface portion 14a has a relatively larger diameter than the front inner circumferential surface portion 14b, thereby reducing the maximum insertion load when inserting the gasket 1 into the annular gap G.

[0048] In the gasket 1 of the modified example shown in FIG. 9, a groove 15 is formed in the rear end surface 12 of the main body 10, thereby providing a weak point with low rigidity in the rear portion of the main body 10 in the insertion direction V1. More specifically, in the gasket 1 shown in FIG. 9, the rear end surface 12 is composed of a radial outer end surface 12a and a radial inner end surface 12b. The outer end surface 12a and the inner end surface 12b are each formed as a flat annular surface. A step is formed between the outer end surface 12a and the inner end surface 12b, and the inner end surface 12b is moved toward the tip surface 11. The entire outer end surface 12a and the inner end surface 12b as the rear end surface 12 of the main body 10 can also be called the rear end surface. The groove portion 15 is located between the outer peripheral surface 13 of the main body portion 10 and the inner peripheral surface 14 (more specifically, the rear inner peripheral surface portion 14a) of the main body portion 10, and is a recessed portion over the entire circumferential direction of the rear end face 12. Specifically, the groove portion 15 is formed in a boundary portion (step portion) between the outer end face portion 12a and the inner end face portion 12b of the rear end face (rear end face portion) 12.

[0049] In this way, in the gasket 1 shown in Figs. 5 to 9, the rigidity of the rear part of the main body 10 in the insertion direction V1 is intentionally set low. Therefore, during the insertion process of the shaft member 200, the parts of the main body 10 including the large recessed parts (see Figs. 5 to 8) and the groove parts 15 (see Fig. 9) function as weak points and are elastically deformed flat, and the magnitude of the reaction force acting from the seal part 20 to the outer circumferential surface 201a of the shaft member 200 based on the elastic deformation of the seal part 20 itself decreases. Therefore, after the top 21 of the seal part 20 reaches approximately the position of the outer circumferential surface 201a of the small diameter part 201, the support force of the main body 10 in the rear part in the insertion direction V1 for the seal part 20 is weakened. In detail, the support force (rigidity) of the main body 10 in the rear part in the insertion direction V1 that supports the part including the second inclined surface 23 of the seal part 20 is weakened. Therefore, during the insertion process of the shaft member 200, the magnitude of the reaction force acting from the seal portion 20 to the outer circumferential surface 201a of the shaft member 200 decreases, and the maximum insertion load during the insertion process of the shaft member 200 is lower than the maximum insertion load in the case where there is no weak point as shown in Figures 1 to 3. As a result, the maximum insertion load can be set to the same extent as in the case of a lip-type seal portion.

[0050] Although not shown, in a modified gasket 1 shown in Fig. 9, the rear inner peripheral surface portion 14a may be located radially outward of the front inner peripheral surface portion 14b, and a groove portion 15 may be provided between the rear inner peripheral surface portion 14a and the inner peripheral surface of the cylindrical portion 31 of the reinforcing ring 30. This can more effectively reduce the maximum insertion load. In the gasket 1 shown in Fig. 9, a step portion is formed on the rear end face 12, but this step portion does not have to be formed.

[0051] In the above description, the gasket 1 is inserted into the axial hole 101 of the housing 100, and the shaft member 200 is inserted into the gasket 1, so that the gasket 1 is inserted into the annular gap G between the housing 100 and the shaft member 200. However, this is not limiting, and the gasket 1 may be inserted into the annular gap G with the shaft member 200 inserted into the axial hole 101 of the housing 100. In this case, the maximum insertion load when inserting the gasket 1 into the annular gap G is substantially the same as the maximum insertion load for the shaft member 200. The insertion direction V1 of the gasket 1 and the insertion direction V2 of the shaft member 200 may be the same.

[0052] In the above description, the gasket 1 has the reinforcing ring 30, but this is not limiting and the gasket 1 may not have the reinforcing ring 30. In this case, the portion corresponding to the reinforcing ring 30 may be formed integrally with the main body 10 using a member made of the same material as the main body 10. Furthermore, the machine to which the gasket 1 is attached is not limited to a CVT, but may be any machine in which an annular gap is formed between a housing and a shaft member at least partially inserted into the housing and which needs to seal this annular gap.

[0053] Although the preferred embodiments of the present invention and some of their modifications have been described above, the present invention is not limited to the above-mentioned embodiments and modifications, and various modifications and changes are possible based on the technical concept of the present invention. [Industrial Applicability]

[0054] The present invention is useful for facilitating the assembly of a gasket into an annular gap. [Explanation of symbols]

[0055] 1...gasket, 10...main body portion, 12...rear end surface of main body portion, 14...inner surface of main body portion, 14a...rear inner surface portion, 14b...front inner surface portion, 15...groove portion, 20...seal portion, 21...top of seal portion, 100...housing, 200...shaft member, 201a...outer surface of shaft member, G...annular gap, V...insertion direction.

Claims

1. A gasket that is inserted into an annular gap between a housing having a cylindrical inner circumferential surface and a shaft member at least a portion of which is inserted into the housing, from one end side of the shaft member toward the other end side, a cylindrical main body portion that is inserted into the housing and fixed to the housing, wherein a radial distance from an axis of the shaft member to an outer circumferential contact surface of the main body portion that contacts the inner circumferential surface of the housing is constant over an entire outer circumferential contact surface of the main body portion; A reinforcing ring embedded inside the main body portion to reinforce and support the main body portion; a seal portion extending from an inner circumferential surface of the main body portion and abutting against an outer circumferential surface of the shaft member; Including, the seal portion is a protrusion that extends circumferentially over an entire area of ​​the inner circumferential surface of the main body, at an intermediate area in the insertion direction between a front inner circumferential surface portion that is a portion forward of the seal portion in the insertion direction and a rear inner circumferential surface portion that is a portion rearward of the seal portion in the insertion direction, and that protrudes inward in the radial direction, the protrusion having two inclined surfaces on both sides of the inclined surface that are inclined in opposite directions to each other in the radial direction, the inclined surfaces extending from an apex that is a portion that abuts against the outer circumferential surface of the shaft member to the front inner circumferential surface portion and the rear inner circumferential surface portion, and a thickness between the two inclined surfaces along the insertion direction that increases from the apex toward the radially outward direction, the reinforcing ring includes a cylindrical portion extending between a rear end surface and a front end surface of the main body portion in the insertion direction, and a flange-shaped inward flange portion extending radially inward from an end of the cylindrical portion on the front end surface side of the main body portion, the gasket does not include a lip-type seal portion that extends over the entire circumferential direction, extends obliquely from the inner peripheral surface of the main body, and has a tip portion that contacts the outer peripheral surface of the shaft member, has two inclined surfaces on both sides of the tip portion that are inclined toward the same side with respect to the radial direction, and has a thickness along the insertion direction between the two inclined surfaces that increases from the tip portion toward the radially outward direction, a cross section of the gasket passing through the most distal end of the ridge in the protruding direction of the ridge and perpendicular to the shaft member is continuously filled with cross sections of the main body portion, the seal portion, and the reinforcing ring over the entire area from the most distal end to the outer circumferential contact surface of the main body portion fixed to the housing, and does not include a cross section of an empty space; gasket.

2. The gasket according to claim 1 , wherein an annular groove is formed in the rear end surface of the main body.

3. 2. The gasket of claim 1, wherein a rear inner circumferential surface portion, which is a portion of the inner circumferential surface of the main body that is rearward of the seal portion in the insertion direction, is located radially outward of a front inner circumferential surface portion, which is a portion of the inner circumferential surface of the main body that is forward of the seal portion in the insertion direction.

4. The gasket according to claim 1 , wherein the top of the sealing portion is formed of a flat surface that extends parallel to the outer circumferential surface of the shaft member.

5. The top of the seal portion is formed of a flat surface that extends parallel to the outer circumferential surface of the shaft member, 2. The gasket according to claim 1, wherein a rear inner circumferential surface portion, which is a rear portion of the inner circumferential surface of the main body portion relative to the seal portion in the insertion direction, and a front inner circumferential surface portion, which is a front portion of the inner circumferential surface of the main body portion, are cylindrical surfaces that extend parallel to each other and are parallel to the outer circumferential surface of the shaft member, and the rear inner circumferential surface portion has a relatively larger diameter than the front inner circumferential surface portion.

Images