Sealing device

Abstract

This sealing device seals an annular gap between an outer peripheral surface of a rotating body and an inner peripheral surface of a housing, the sealing device including: an annular elastic body; and a covering part which covers the inner peripheral surface of the elastic body, has a lower coefficient of friction than the coefficient of friction of the elastic body, and is in contact with the outer peripheral surface of the rotating body. On the inner peripheral surface of the elastic body, a protrusion for suppressing scattering of the material of the covering part during formation of the covering part is formed. The protrusion protrudes radially inward from the inner peripheral surface of the elastic body and extends along the circumferential direction of the inner peripheral surface.

Description

Sealing device

[0001] The present disclosure relates to a sealing device.

[0002] Various sealing devices for sealing an annular gap between an outer peripheral surface of a rotating body and an inner peripheral surface of a housing have been conventionally proposed. For example, Patent Document 1 discloses an oil seal including an annular metal ring, an elastic body integrally formed with the metal ring, and a garter spring that presses the elastic body inward.

[0003] Japanese Patent Application Laid-Open No. 2012-117611

[0004] In the configuration of Patent Document 1, a lip end of a seal lip formed on an inner peripheral surface of the elastic body contacts an outer peripheral surface of the shaft. In order to reduce the torque of the sealing device with respect to the rotating body, a method is assumed in which the inner peripheral surface of the elastic body is covered with a covering portion having a lower coefficient of kinetic friction than the lip end, and the covering portion rather than the lip end is brought into contact with the outer peripheral surface of the rotating body. However, when the inner peripheral surface of the elastic body is smooth, there is a problem that the material of the covering portion scatters and the covering portion is formed even in unnecessary portions. In consideration of the above circumstances, one aspect of the present disclosure aims to suppress the diffusion of the material of the covering portion to a range excessively wider than the range where the covering portion should be formed.

[0005] In order to solve the above problems, a sealing device according to one aspect of the present disclosure is a sealing device that seals an annular gap between an outer peripheral surface of a rotating body and an inner peripheral surface of a housing, and includes an annular elastic body and a covering portion that covers an inner peripheral surface of the elastic body, has a lower coefficient of friction than the coefficient of friction of the elastic body, and abuts on the outer peripheral surface of the rotating body. On the inner peripheral surface of the elastic body, a protrusion is formed for suppressing the scattering of the material of the covering portion at the time of forming the covering portion. The protrusion protrudes radially inward from the inner peripheral surface of the elastic body and extends along the circumferential direction of the inner peripheral surface.

[0006] A sealing device according to one aspect of the present disclosure is a sealing device for sealing an annular gap between the outer circumferential surface of a rotating body and the inner circumferential surface of a housing, comprising an annular elastic body and a covering portion that covers the inner circumferential surface of the elastic body, has a coefficient of friction lower than that of the elastic body, and contacts the outer circumferential surface of the rotating body, wherein a projection is formed on the inner circumferential surface of the elastic body, the projection protrudes radially inward from the inner circumferential surface of the elastic body and extends along the circumferential direction of the inner circumferential surface, and the covering portion covers the projection.

[0007] This is a cross-sectional view of the sealing structure in the first embodiment. This is an enlarged view of the seal lip in the first embodiment. This is a flowchart illustrating the manufacturing method of the sealing device in the first embodiment. This is a schematic diagram of the reinforcing ring and elastic body formed in the molding process in the first embodiment. This is a schematic diagram of the coating process in the first embodiment. This is a schematic diagram of the coating process in proportion. This is a schematic diagram of the cutting process in the first embodiment. This is a cross-sectional view of the sealing structure in the second embodiment. This is an enlarged view of the sealing device in the second embodiment.

[0008] The embodiments for implementing this disclosure will be described with reference to the drawings. Note that the dimensions and scale of the elements in each drawing may differ from those of the actual product. Furthermore, the embodiments described below are illustrative examples of embodiments that may be envisioned when implementing this disclosure. Therefore, the scope of this disclosure is not limited to the embodiments exemplified below.

[0009] A: Figure 1 of the first embodiment is a cross-sectional view of the sealing structure 100 in the first embodiment. The sealing structure 100 is a mechanism used in various machines, such as automobiles. As illustrated in Figure 1, the sealing structure 100 comprises a housing 1, a rotating body 2, and a sealing device 3. In Figure 1, the external shapes of the housing 1 and the rotating body 2 are shown by dashed lines for convenience.

[0010] Housing 1 is a hollow structure with an opening 11 formed therein. The opening 11 is a through hole with a circular cross-sectional shape of a predetermined diameter. Rotating body 2 is a cylindrical structure inserted into the opening 11. Rotating body 2 is installed concentrically with the opening 11. Therefore, an annular gap S is formed between the inner circumferential surface 10 of the opening 11 of housing 1 and the outer circumferential surface 20 of rotating body 2. Sealing device 3 is an annular structure that seals the gap S. The gap S is divided into a first space S1 and a second space S2 with the sealing device 3 in between. Oil is contained in the first space S1, and the second space S2 is open to the atmosphere. The sealing device 3 of the first embodiment is an oil seal that seals oil in the first space S1.

[0011] In the following explanation, we assume that the central axis C of the sealing device 3 is central. One direction along the central axis C is denoted as the Z1 direction, and the direction opposite to the Z1 direction is denoted as the Z2 direction. The Z1 direction is an example of the "first direction," and the Z2 direction is an example of the "second direction." The first space S1 is located in the Z1 direction of the second space S2. The central axis C can also be described as the central axis C of the opening 11 of the housing 1, or the central axis C of the rotation axis. The rotating body 2 is rotatable about the central axis C.

[0012] Furthermore, the direction along the circumference of a virtual circle of any diameter centered on the central axis C is referred to as the "circumferential direction," and the direction of the radius of the said virtual circle is referred to as the "radial direction." In the radial direction, the direction toward the central axis C is referred to as the "inside," and the direction toward the opposite side of the central axis C is referred to as the "outside."

[0013] The sealing device 3 comprises a reinforcing ring 30, an elastic body 40, a covering portion 60, and a garter spring 70. Each of the reinforcing ring 30, the elastic body 40, the covering portion 60, and the garter spring 70 is an annular member for surrounding the rotating body 2.

[0014] The reinforcing ring 30 is a structure that reinforces the elastic body 40. The reinforcing ring 30 is a highly rigid metal ring formed from, for example, a metallic material. Examples of materials for the reinforcing ring 30 include stainless steel, SPCC (Steel Plate Cold Commercial), or SPHC (Steel Plate Hot Commercial).

[0015] The reinforcing ring 30 includes a cylindrical portion 31 and a flange portion 32. The cylindrical portion 31 is a cylindrical part that surrounds the rotating body 2. The flange portion 32 is an annular plate-like portion of the cylindrical portion 31 that protrudes radially inward from the peripheral edge in the Z2 direction.

[0016] The elastic body 40 is an annular structure installed on the reinforcing ring 30. The elastic body 40 is made of various elastic materials. For example, it can be made of any rubber material such as chloroprene rubber (CR), silicone rubber (SR), acrylic rubber (ACM), urethane rubber (U), polyurethane rubber (PUR), vinyl methyl silicone rubber (VMQ), ethylene propylene diene rubber (EPDM), or fluororubber (FKM). The elastic body 40 is formed integrally with the reinforcing ring 30, for example, by insert molding.

[0017] The elastic body 40 is a structure in which an outer periphery 41, an intermediate portion 42, and an inner periphery 43 are integrally formed. The inner periphery 43 is located radially inward relative to the outer periphery 41. The outer periphery 41 and the inner periphery 43 are connected by the intermediate portion 42. The outer periphery 41 is an annular portion that extends in the axial direction. The outer circumferential surface of the outer periphery 41 is in contact with the inner circumferential surface 10 of the housing 1. The outer periphery 41 covers the surface of the cylindrical portion 31 of the reinforcing ring 30. The intermediate portion 42 is a flange portion that connects the outer periphery 41 and the inner periphery 43 and extends in the radial direction. Specifically, the intermediate portion 42 connects the end of the outer periphery 41 in the Z2 direction to the end of the inner periphery 43 in the Z2 direction. The intermediate portion 42 covers the surface of the flange portion 32 of the reinforcing ring 30. That is, the reinforcing ring 30 is covered by the elastic body 40.

[0018] The inner circumference 43 is located radially inward from the outer circumference 41 and is an annular portion that extends in the axial direction. The inner surface of the inner circumference 43 faces the outer surface 20 of the rotating body 2. The inner circumference 43 includes a base 44, a dust lip 45, a seal lip 46, a projection 47, and a groove 48.

[0019] The base portion 44 is an annular portion that extends in the axial direction. The end of the base portion 44 in the Z2 direction connects to the radially inner end of the intermediate portion 42. The base portion 44 covers the vicinity of the radially inner end of the flange portion 32.

[0020] The dust lip 45 is an annular lip that protrudes from the base 44 in the Z2 direction. The dust lip 45 protrudes in a direction inclined with respect to the central axis C such that its tip is located near the central axis C compared to the base. The tip of the dust lip 45 contacts the outer circumferential surface 20 of the rotating body 2. That is, when the rotating body 2 is rotating, the tip of the dust lip 45 slides against the outer circumferential surface 20 of the rotating body 2. The dust lip 45 is an auxiliary lip that prevents foreign matter such as dust from entering the first space S1 from the second space S2.

[0021] The seal lip 46 is an annular lip projecting from the base 44 in the Z1 direction. The seal lip 46 is located in the Z1 direction relative to the dust lip 45. The seal lip 46 is the main lip that seals the first space S1. Figure 2 is an enlarged view of the seal lip 46. As illustrated in Figure 1 or Figure 2, the inner circumferential surface of the seal lip 46 includes a first surface F1 and a second surface F2 that intersect each other.

[0022] The first surface F1 is inclined to approach the central axis C in the Z1 direction, and the second surface F2 is inclined to move away from the central axis C in the Z1 direction. That is, the first surface F1 and the second surface F2 form a roughly triangular cross-sectional shape. The second surface F2 is located in the Z1 direction relative to the first surface F1 in the axial direction. In this disclosure, the point where the first surface F1 and the second surface F2 intersect is referred to as the "lip end 49".

[0023] The projection 47 is formed on the inner circumferential surface of the inner circumferential portion 43. Specifically, the projection 47 is formed on the first surface F1. More specifically, the projection 47 is located in the axial direction between the lip end 49 of the seal lip 46 and the dust lip 45. The projection 47 protrudes radially inward from the first surface F1 and extends along the circumferential direction. Specifically, the projection 47 is continuous in an annular shape around the entire circumference of the first surface F1. Since the projection 47 is located radially outward from the lip end 49 in a plan view, it does not come into contact with the outer circumferential surface 20 of the rotating body 2.

[0024] As illustrated in Figure 1, the outer circumferential surface of the seal lip 46 faces the inner circumferential surface of the outer circumferential portion 41 of the elastic body 40 at a distance from it. An annular groove 48 is formed on the outer circumferential surface of the seal lip 46, extending in the circumferential direction. The groove 48 is formed radially outward from the lip end 49, as illustrated in Figure 1 or Figure 2. That is, the lip end 49 is located within the range in which the groove 48 is formed in the axial direction. A girder spring 70 is installed in the groove 48.

[0025] The garter spring 70 is an annular elastic member that tightens the lip end 49. For example, a coil spring made of a metal material such as stainless steel can be used as the garter spring 70. The garter spring 70 is installed in the groove 48. The lip end 49 is pressed toward the outer circumferential surface 20 of the rotating body 2 by being tightened by the garter spring 70. Note that the sealing device 3 does not necessarily need to be equipped with a garter spring 70.

[0026] As illustrated in Figure 2, the area D1 on the first surface F1 where the projection 47 exists in the axial direction is located within the area D2 where the garter spring 70 exists in the axial direction.

[0027] As illustrated in Figure 1 or Figure 2, the covering portion 60 covers the inner circumferential surface of the elastic body 40. Specifically, the covering portion 60 covers the area between the projection 47 and the lip end 49 on the first surface F1. The covering portion 60 covers the area from a position in the Z1 direction relative to the apex of the projection 47 on the first surface F1 to the peripheral edge of the first surface F1 in the Z1 direction. That is, the covering portion 60 partially covers the projection 47. The rigidity of the covering portion 60 is higher than that of the elastic body 40. The coefficient of dynamic friction of the covering portion 60 is lower than that of the elastic body 40. As the material of the covering portion 60, a resin material such as polytetrafluoroethylene (PTFE) may be used. However, the material of the covering portion 60 is not limited to the above examples.

[0028] As illustrated in Figure 2, the end face 61 of the covering portion 60 in the Z1 direction is located in the same plane as the second surface F2. Therefore, the radially inner end 62 of the covering portion 60 is located radially inward relative to the lip end 49 in a plan view. Consequently, the radially inner end 62 of the covering portion 60 abuts against the outer circumferential surface 20 of the rotating body 2. When the rotating body 2 is rotating, the radially inner end 62 of the covering portion 60 slides against the outer circumferential surface 20 of the rotating body 2. Therefore, compared to a configuration in which the lip end 49 abuts against the outer circumferential surface 20 of the rotating body 2, the torque of the sealing device 3 on the rotating body 2 is reduced.

[0029] Here, we will explain the manufacturing method of the sealing device 3. Figure 3 is a flowchart illustrating the manufacturing method of the sealing device 3.

[0030] First, in the molding process P1, the elastic body 40 is vulcanized and bonded to the reinforcing ring 30, and the reinforcing ring 30 and the elastic body 40 are integrally molded. Figure 4 is a schematic diagram of the reinforcing ring 30 and the elastic body 40 molded in the molding process P1 in the first embodiment. As illustrated in Figure 4, the inner circumference 43 of the molded elastic body 40 further includes a burr portion 50 that protrudes in the Z1 direction.

[0031] Figure 5 is a schematic diagram of the coating process P2 in the first embodiment. As illustrated in Figure 5, in the coating process P2 after the molding process P1, the coating material 63 is applied to the first surface F1. Specifically, the dispenser 80 dispenses the liquid coating material 63 onto the first surface F1. The material 63 applied to the first surface F1 flows axially across the first surface F1 due to the force of the dispensing by the dispenser 80. After dispensing, the material 63 hardens, forming the coating 60 on the first surface F1.

[0032] Figure 6 is a schematic diagram of the coating process P2 in a configuration in which no protrusions 47 are formed on the first surface F1 (hereinafter referred to as "proportional"). As illustrated in Figure 6, in the process of forming a coating portion 60 on the first surface F1, in the proportional configuration, the material 63 of the coating portion 60 flows to an excessively wide area in addition to the area in which the coating portion 60 is formed. In contrast, as illustrated in Figure 5, in the first embodiment, the protrusions 47 act as an obstacle and prevent the material 63 of the coating portion 60 from spreading in the Z2 direction. Therefore, it is possible to suppress the diffusion of the material 63 of the coating portion 60 to an excessively wide area in addition to the area in which the coating portion 60 should be formed.

[0033] In the cutting step P3 following the coating step P2, the coating portion 60 and the inner circumference portion 43 are cut. Figure 7 is a schematic diagram of the cutting step P3 in the first embodiment. As illustrated in Figure 7, the coating portion 60 and the inner circumference portion 43 are cut at a predetermined angle. The dotted line in Figure 7 indicates the cut surface formed by cutting the coating portion 60 and the inner circumference portion 43 at a predetermined angle. The radially inner end of the cut surface is located in the Z1 direction relative to the projection portion 47 in the axial direction. The burr portion 50 located in the Z1 direction relative to the cut surface and the coating portion 60 covering the burr portion 50 are discarded. The cut surface corresponds to the second surface F2 of the seal lip 46 and the end surface 61 of the coating portion 60 in the Z1 direction. That is, the end surface 61 of the coating portion 60 in the Z1 direction is located in the same plane as the second surface F2. By cutting the burr portion 50, the seal lip 46 and the lip end 49 are formed.

[0034] In the mounting process P4 following the execution of the cutting process P3, the garter spring 70 is mounted in the groove 48, as illustrated in Figure 1.

[0035] As described above, according to the manufacturing method, the protrusions 47 act as an obstruction, preventing the material 63 of the covering portion 60 from spreading. Therefore, it is possible to suppress the diffusion of the material of the covering portion 60 over an excessively wide area than the area in which the covering portion 60 should be formed.

[0036] B: Second Embodiment A second embodiment of the present disclosure will be described. In each of the embodiments described below, elements whose function is the same as in the first embodiment will use the same reference numerals as in the description of the first embodiment, and detailed descriptions of each will be omitted as appropriate.

[0037] Figure 8 is a cross-sectional view of the sealing structure 100 in the second embodiment. As illustrated in Figure 8, the sealing structure 100 includes a housing 1, a rotating body 2, and a plurality of sealing devices (3a, 3b). The rotating body 2 and the plurality of sealing devices (3a, 3b) are installed inside the housing 1.

[0038] Housing 1 includes a body 12, a first pipe 13, a second pipe 14, and a third pipe 15. The first pipe 13, the second pipe 14, and the third pipe 15 are connected to the body 12. The body 12 is a hollow structure and has an internal space S3. Through holes (16a, 16b, 16c) are formed on the exterior surfaces of the body 12 that face the end faces of each pipe. Specifically, the body 12 has a through hole 16a that penetrates the surface facing the end face of the first pipe 13, a through hole 16b that penetrates the surface facing the end face of the second pipe 14, and a through hole 16c that penetrates the surface facing the end face of the third pipe 15. The through hole 16a communicates with the inside of the first pipe 13. The through hole 16b communicates with the inside of the second pipe 14. The through hole 16c communicates with the inside of the third pipe 15. The through holes 16a, 16b, and 16c communicate with the internal space S3. Therefore, the first pipe 13, the second pipe 14, and the third pipe 15 are connected via the internal space S3. The body 12 can be made of resin or metal.

[0039] The body 12 is provided with annular grooves 19 on the surface facing the second pipe 14 and the surface facing the third pipe 15. The inner diameter R1 of the annular groove 19 is larger than the inner diameter R2 of the through holes (16b, 16c). The annular groove 19 is an annular recess.

[0040] The first pipe 13, the second pipe 14, and the third pipe 15 are gas passages. The first pipe 13 is a passage for supplying gas to the body 12. The second pipe 14 and the third pipe 15 are passages through which the gas supplied to the internal space S3 of the body 12 via the first pipe 13 flows. Resin or metal materials can be used for each pipe.

[0041] The rotating body 2 includes a shaft portion 21 and a valve body portion 22. The shaft portion 21 and the valve body portion 22 are integrally formed of, for example, various resin materials. The shaft portion 21 is a columnar portion that can rotate about the central axis C. The central axis C corresponds to the central axis of the shaft portion 21.

[0042] In the following description, one direction along the central axis C is denoted as the Z1 direction, and the direction opposite to the Z1 direction is denoted as the Z2 direction. Further, one direction orthogonal to the central axis C is taken as the Y1 direction, and the direction opposite to the Y1 direction is taken as the Y2 direction. That is, the direction of the Z axis and the direction of the Y axis are orthogonal. The end portion of the shaft portion 21 in the Z2 direction is directly or indirectly connected to a motor (not shown). The shaft portion 21 rotates about the central axis C in conjunction with the operation of the motor.

[0043] The valve body portion 22 is a portion that can rotate together with the shaft portion 21 about the central axis C. The valve body portion 22 is a hemispherical shell-like structure, and the end portion in the direction of the Z axis is connected to the shaft portion 21. The valve body portion 22 faces the opening 17 of the second pipe 14 or the opening 18 of the third pipe 15. That is, the rotating body 2 is a mechanism for selectively communicating the first pipe 13 with either the second pipe 14 or the third pipe 15. The state in which the gas supplied from the first pipe 13 to the internal space S3 of the body 12 is discharged from the second pipe 14 and the state in which the gas in the internal space S3 is discharged from the third pipe 15 are switched from one to the other according to the direction of the valve body portion 22.

[0044] The plurality of sealing devices (3a, 3b) are devices for sealing the gap between the housing 1 and the rotating body 2. Specifically, the sealing device 3a seals the gap between the body 12, the second pipe 14, and the rotating body 2. The sealing device 3b seals the gap between the body 12, the third pipe 15, and the rotating body 2. The plurality of sealing devices (3a, 3b) include elastic bodies (40a, 40b) and a covering portion 60.

[0045] FIG. 9 is an enlarged view of the sealing device 3a in the second embodiment. As illustrated in FIG. 9, the elastic body 40a is an annular structure. The elastic body 40a includes an outer peripheral portion 41, an inner peripheral portion 43, and a plurality of protrusion portions 47. The outer peripheral portion 41 is a cylindrical portion extending in the direction of the Y axis. The outer peripheral portion 41 is inserted into the annular groove 19 to fix the elastic body 40a to the body 12.

[0046] The inner peripheral portion 43 is an annular portion curved in an arc shape. The cross-sectional shape of the inner peripheral portion 43 is a substantially semi-circular shape that curves concave toward the inner side in the radial direction of the elastic body 40a. The end portion of the inner peripheral portion 43 in the Y2 direction and the end portion of the outer peripheral portion 41 in the Y2 direction are connected. The outer diameter of the end portion of the outer peripheral portion 41 in the Y2 direction is larger than the outer diameter of the end portion of the inner peripheral portion 43 in the Y1 direction.

[0047] The plurality of protrusions 47 are formed on the inner peripheral surface F3 of the elastic body 40a. Specifically, four protrusions 47 are formed on the portion of the inner peripheral surface of the inner peripheral portion 43 that is located in the Y1 direction. The four protrusions 47 are formed at intervals in the Z-axis direction. Each protrusion 47 protrudes radially inward from the inner peripheral surface of the inner peripheral portion 43 into the elastic body 40a and extends along the circumferential direction of the elastic body 40a. Specifically, the protrusion 47 is continuously annular over the inner peripheral surface of the inner peripheral portion 43.

[0048] The covering portion 60 covers the inner peripheral surface F3 of the elastic body 40a. Specifically, the covering portion 60 covers the inner peripheral surface of the inner peripheral portion 43 so as to cover all four protrusions 47. The coefficient of kinetic friction of the covering portion 60 is lower than the coefficient of kinetic friction of the elastic body 40a. The inner peripheral surface of the covering portion 60 abuts against the outer peripheral surface 23 of the valve body portion 22 of the rotating body 2. That is, in a state where the valve body portion 22 rotates, the inner peripheral surface of the covering portion 60 slides with respect to the outer peripheral surface 23 of the valve body portion 22. Therefore, compared with a configuration in which the inner peripheral surface of the elastic body 40a abuts against the outer peripheral surface 23 of the valve body portion 22, the torque of the sealing device 3a with respect to the rotating body 2 is reduced.

[0049] In a configuration where the protrusions 47 are not formed on the inner peripheral surface F3 of the elastic body 40a, when the inner peripheral surface of the covering portion 60 slides with respect to the outer peripheral surface 23 of the valve body portion 22, due to the circumferential frictional force acting on the covering portion 60 from the rotating body 2, the covering portion 60 may shift from the position where it covers the inner peripheral surface F3 of the elastic body 40a. In contrast, in the second embodiment, even when the inner peripheral surface of the covering portion 60 slides with respect to the outer peripheral surface 23 of the valve body portion 22, the plurality of protrusions 47 support the covering portion 60, reducing the possibility that the covering portion 60 shifts from the position where it covers the inner peripheral surface F3 of the elastic body 40a.

[0050] When the valve body 22 rotates to a position facing the opening 17 of the second pipe 14, the sealing device 3a seals the gap between the second pipe 14, the body 12, and the valve body 22. As a result, gas supplied to the internal space S3 of the body 12 via the first pipe 13 is prevented from leaking from the internal space S3 of the body 12 into the second pipe 14.

[0051] In the above explanation, we have focused on the sealing device 3a, but the sealing device 3a and the sealing device 3b are symmetrical with respect to the central axis C. Specifically, the elastic body 40b includes an outer circumference 41 and an inner circumference 43. The outer circumference 41 is a cylindrical portion that extends in the direction of the Y axis. The outer circumference 41 is inserted into the annular groove 19 in order to fix the elastic body 40b to the body 12.

[0052] The inner circumference 43 is an annular portion that is curved in an arc. The cross-sectional shape of the inner circumference 43 is a roughly semicircular shape that curves concavely toward the radially inward direction of the elastic body 40b. The end of the inner circumference 43 in the Y1 direction and the end of the outer circumference 41 in the Y1 direction are connected. The outer diameter of the end of the outer circumference 41 in the Y1 direction is larger than the outer diameter of the end of the inner circumference 43 in the Y2 direction.

[0053] Multiple protrusions 47 are formed on the inner circumferential surface F4 of the elastic body 40b. Specifically, four protrusions 47 are formed on the portion of the inner circumferential surface of the inner circumferential portion 43 located in the Y2 direction. The four protrusions 47 are formed spaced apart in the Z-axis direction. Each protrusion 47 projects radially inward from the inner circumferential surface of the inner circumferential portion 43 and extends along the circumferential direction of the elastic body 40b. Specifically, the protrusions 47 are continuous in an annular shape across the inner circumferential surface of the inner circumferential portion 43.

[0054] The covering portion 60 covers the inner circumferential surface F4 of the elastic body 40b. Specifically, the covering portion 60 covers the inner circumferential surface of the inner circumferential portion 43 so as to cover all four protrusions 47. The dynamic friction coefficient of the covering portion 60 is lower than that of the elastic body 40b. The inner circumferential surface of the covering portion 60 abuts against the outer circumferential surface 23 of the valve body portion 22 on the rotating body 2. That is, when the valve body portion 22 is rotating, the inner circumferential surface of the covering portion 60 slides against the outer circumferential surface 23 of the valve body portion 22. Therefore, compared to a configuration in which the inner circumferential surface of the elastic body 40b abuts against the outer circumferential surface 23 of the valve body portion 22, the torque of the sealing device 3b on the rotating body 2 is reduced.

[0055] In the configuration where no projections 47 are formed on the inner circumferential surface F4 of the elastic body 40b, when the inner circumferential surface of the covering portion 60 slides against the outer circumferential surface 23 of the valve body portion 22, the circumferential frictional force acting on the covering portion 60 from the position in which the covering portion 60 covers the inner circumferential surface F4 of the elastic body 40b may cause the covering portion 60 to shift from its position in which it covers the inner circumferential surface F4 of the elastic body 40b. In contrast, in the second embodiment, even when the inner circumferential surface of the covering portion 60 slides against the outer circumferential surface 23 of the valve body portion 22, the multiple projections 47 support the covering portion 60, thereby reducing the possibility of the covering portion 60 shifting from the position in which it covers the inner circumferential surface F4 of the elastic body 40b.

[0056] When the valve body 22 rotates to a position facing the opening 18 of the third pipe 15, the sealing device 3b seals the gap between the third pipe 15, the body 12, and the valve body 22. As a result, gas supplied to the internal space S3 of the body 12 via the first pipe 13 is prevented from leaking from the internal space S3 of the body 12 into the third pipe 15.

[0057] C: Examples of specific modifications that may be added to each of the embodiments exemplified above are given below. Two or more embodiments may be arbitrarily selected from the following examples and merged as appropriate, within the bounds of consistency.

[0058] (1) In the first embodiment, a configuration in which there is one projection 47 in the axial direction was shown. However, the number of projections 47 in the axial direction is not limited to the above examples. For example, a configuration in which multiple projections 47 are arranged at intervals in the axial direction is also possible.

[0059] (2) In the first embodiment, a configuration in which the covering portion 60 partially covers the projection portion 47 was illustrated. However, the relationship between the covering portion 60 and the projection portion 47 is not limited to the above examples. For example, the covering portion 60 may completely cover the projection portion 47, or the covering portion 60 may not cover the projection portion 47.

[0060] (3) In the first embodiment, a configuration in which the projection 47 is formed on the first surface F1 of the seal lip 46 was illustrated, but the position of the projection 47 on the inner circumference 43 may be changed. For example, the projection 47 may be formed on the inner surface of the base 44 or on the inner surface of the dust lip 45 within the inner circumference 43.

[0061] (4) In the first embodiment, a configuration in which oil is contained in the first space S1 was shown, but a fluid other than oil may be contained in the first space S1. For example, a configuration in which a gas such as air or a liquid such as water is contained may be used.

[0062] (5) In the first embodiment, the inner circumference 43 is shown to include the dust lip 45, but the inner circumference 43 may also be configured not to include the dust lip 45.

[0063] (6) In the first embodiment, the range D1 in which the projection 47 exists in the axial direction is shown to be within the range D2 in which the garter spring 70 exists in the axial direction. However, if the projection 47 is located in the Z2 direction relative to the lip end 49 in the axial direction, the range D1 in which the projection 47 exists in the axial direction may only partially overlap with the range D2 in which the garter spring 70 exists in the axial direction.

[0064] (7) In the second embodiment, a configuration was shown in which the covering portion 60 covers the inner surface of the inner circumference portion 43 so as to cover all four protrusions 47. However, the relationship between the covering portion 60 and the protrusions 47 is not limited to the above example. For example, the covering portion 60 may partially cover multiple protrusions 47, or the covering portion 60 may not cover multiple protrusions 47.

[0065] (8) In the embodiments described above, annular projections 47 were shown to be formed over the entire circumference of the inner surface of the elastic body (40, 40a, 40b), but the configuration of the projections 47 is not limited to the above configuration. For example, discontinuous projections 47 may extend along the circumferential direction on the inner surface of the elastic body (40, 40a, 40b).

[0066] (9) The notation "nth" (where n is a natural number) in this application is used solely as a formal and convenient label to distinguish each element in notation and has no substantive meaning whatsoever. Therefore, there is no room for restrictive interpretation of the position or manufacturing order of each element based on the notation "nth".

[0067] D: From the forms exemplified above, the following configurations can be understood, for example.

[0068] A sealing device according to one aspect of the present disclosure (Aspect 1) is a sealing device for sealing an annular gap between the outer circumferential surface of a rotating body and the inner circumferential surface of a housing, comprising: an annular elastic body; and a covering portion that covers the inner circumferential surface of the elastic body, has a coefficient of friction lower than that of the elastic body, and contacts the outer circumferential surface of the rotating body, wherein a projection is formed on the inner circumferential surface of the elastic body to suppress the scattering of the material of the covering portion when the covering portion is formed, the projection protrudes radially inward from the inner circumferential surface of the elastic body and extends along the circumferential direction of the inner circumferential surface. In the above aspect, when the covering portion is formed on the inner circumferential surface of the elastic body, if the projection is not formed on the inner circumferential surface, the material of the covering portion will scatter over an excessively wide area than the area in which the covering portion should be formed. In contrast, in the aspect where the projection is formed on the inner circumferential surface, the projection acts as an obstacle and prevents the scattering of the material of the covering portion. Therefore, it is possible to suppress the diffusion of the material of the covering portion over an excessively wide area than the area in which the covering portion should be formed. Furthermore, "rotating body" refers to an object that rotates relative to the housing, such as a rotating shaft or the spherical valve body of a valve.

[0069] In the specific example of Embodiment 1 (Embodiment 2), the sealing device includes an elastic body comprising a first surface which is a part of the inner circumferential surface of the elastic body on which the projection is formed, and a second surface which is located in a first direction along the central axis of the elastic body relative to the first surface. The portion of the elastic body where the first surface and the second surface intersect forms a lip end which is located radially inward from the projection in a plan view, and the covering portion covers the first surface, with the end face of the covering portion in the first direction located in the same plane as the second surface. In the above embodiment, the contact portion between the sealing device and the outer circumferential surface of the rotating body is the covering portion which covers the first surface. With the above configuration, torque can be reduced because the contact portion with the rotating body is smaller compared to a configuration in which the lip end and the covering portion each abut the outer circumferential surface of the rotating body.

[0070] The sealing device in embodiment 1 or a specific example of embodiment 2 (embodiment 3) further comprises an annular garter spring that presses the outer circumferential surface of the first surface radially inward of the elastic body, and the projection is located within the range where the garter spring exists in the axial direction of the central axis. In the above embodiment, the first surface is pressed inward by the garter spring. That is, the lip end is pressed inward by the garter spring. Therefore, compared to a configuration in which the sealing device does not include a garter spring, an appropriate contact pressure is ensured between the outer circumferential surface of the rotating body and the lip end.

[0071] In any specific example of Embodiments 1 to 3 (Embodiment 4), the sealing device further comprises a dust lip in which the elastic body is positioned in a second direction opposite to the first direction with respect to the projection. In the above embodiment, the dust lip also contacts the outer circumferential surface of the rotating body separately from the covering portion. With the above configuration, compared to a configuration in which a dust lip is not formed on the elastic body, it is possible to suppress the intrusion of dust and debris into the gap between the rotating body and the elastic body.

[0072] In the sealing device in any specific example (5) of Embodiments 1 to 4, the projection is formed over the entire circumference of the inner surface of the elastic body. In the above embodiment, an annular projection is formed over the entire circumference of the inner surface of the elastic body. With the above configuration, there are no gaps in the projection compared to a configuration in which discontinuous projections extend along the circumferential direction on the inner surface of the elastic body. Therefore, the effect of preventing the material of the covering from scattering due to the projection acting as an obstruction becomes more pronounced.

[0073] In the sealing device described in any specific example (6) of Embodiments 1 to 5, the covering portion does not cover the protrusion. According to the above embodiments, the material of the covering portion is less likely to scatter beyond the protrusion. Therefore, a significant effect is achieved in that the diffusion of the covering portion material over an excessively wide area than the area in which the covering portion should be formed can be suppressed.

[0074] The sealing device in any specific example of Embodiments 1 to 6 (Embodiment 7) includes a plurality of protrusions, including the aforementioned projection, and the plurality of protrusions are positioned at different axial positions relative to the central axis. According to the above embodiments, there are multiple obstructive protrusions. Therefore, a significant effect is achieved in that the diffusion of the coating material over an excessively wide area than the area in which the coating should be formed can be suppressed.

[0075] A specific example of any of embodiments 1 to 7 (embodiment 8) is that the elastic body includes a seal lip located in a first direction along the central axis of the elastic body and including a lip end, and a dust lip located in a second direction opposite to the first direction, and the projection is located between the lip end of the seal lip and the dust lip in the axial direction of the central axis. In the above embodiments, when a covering is formed on the inner circumferential surface of the elastic body, in the configuration where the projection is not formed on the inner circumferential surface, the covering material scatters over an excessively wide area than the area where the covering should be formed. In contrast, in the configuration where the projection is formed on the inner circumferential surface, the projection acts as an obstruction and prevents the covering material from scattering. Therefore, it is possible to suppress the diffusion of the covering material over an excessively wide area than the area where the covering should be formed.

[0076] A specific example of any of embodiments 1 to 7 (embodiment 9) further comprises an annular garter spring that presses the outer circumferential surface of the elastic body radially inward, and the projection is formed on the inner circumferential surface of the elastic body in the area where the garter spring exists in the axial direction of the central axis of the elastic body. In the above embodiments, when a covering portion is formed on the inner circumferential surface of the elastic body, in the configuration where the projection is not formed on the inner circumferential surface, the covering material scatters over an excessively wide area than the area where the covering portion should be formed. In contrast, in the configuration where the projection is formed on the inner circumferential surface, the projection acts as an obstruction and prevents the covering material from scattering. Therefore, it is possible to suppress the diffusion of the covering material over an excessively wide area than the area where the covering portion should be formed.

[0077] A sealing device according to one aspect of the present disclosure (Aspect 10) is a sealing device for sealing an annular gap between the outer circumferential surface of a rotating body and the inner circumferential surface of a housing, comprising: an annular elastic body; and a covering portion that covers the inner circumferential surface of the elastic body, has a coefficient of friction lower than that of the elastic body, and contacts the outer circumferential surface of the rotating body, wherein a projection is formed on the inner circumferential surface of the elastic body, the projection protrudes radially inward from the inner circumferential surface of the elastic body and extends along the circumferential direction of the inner circumferential surface, and the covering portion covers the projection. In a configuration in which no projection is formed on the inner circumferential surface of the elastic body, when the covering portion slides against the outer circumferential surface of the rotating body, the circumferential frictional force acting on the covering portion from the rotating body may cause the covering portion to shift from the position in which it covers the inner circumferential surface of the elastic body. In contrast, according to Aspect 10, even when the covering portion slides against the outer circumferential surface of the rotating body, the projection supports the covering portion, thereby reducing the possibility of the covering portion shifting from the position in which it covers the inner circumferential surface of the elastic body.

[0078] 1...Housing, 2...Rotating body, 3...Sealing device of the first embodiment, 3a...Sealing device of the second embodiment, 3b...Sealing device of the second embodiment, 10...Inner circumferential surface of the housing, 11...Opening of the housing, 12...Body, 13...First pipe, 14...Second pipe, 15...Third pipe, 16a...Through hole penetrating the opposing surface of the first pipe, 16b...Through hole penetrating the opposing surface of the second pipe, 16c ...Through hole penetrating the opposing surface of the third pipe, 17...Opening of the second pipe, 18...Opening of the third pipe, 19...Annular groove, 20...Outer surface of the rotating body, 21...Shaft portion, 22...Valve body portion, 30...Reinforcement ring, 31...Cylindrical portion, 32...Flange portion, 40...Elastic body of the first embodiment, 40a...Elastic body of the second embodiment, 40b...Elastic body of the second embodiment, 41...Outer circumference portion, 42...Intermediate portion, 43...Inner circumference portion, 44 ...base, 45...dust lip, 46...seal lip, 47...projection, 48...groove, 49...lip end, 50...burr, 60...covering part, 61...end of covering part, 62...end face of covering part, 63...material of covering part, 70...garter spring, 80...dispenser, 100...sealing structure, C...central axis of the rotating body, D1...range where projection exists in the axial direction, D2...range where garter spring exists in the axial direction, F1...first surface, F2...second surface, F3...inner circumferential surface of elastic body 40a, F4...inner circumferential surface of elastic body 40b, P1...molding process, P2...covering process, P3...cutting process, P4...mounting process, R1...inner diameter of annular groove, R2...inner diameter of through hole, S...gap between housing and rotating body, S1...first space, S2...second space, S3...internal space of body.

Claims

1. A sealing device for sealing an annular gap between the outer circumferential surface of a rotating body and the inner circumferential surface of a housing, comprising: an annular elastic body; a covering portion that covers the inner circumferential surface of the elastic body, has a coefficient of friction lower than that of the elastic body, and contacts the outer circumferential surface of the rotating body, wherein the inner circumferential surface of the elastic body has projections formed thereon to suppress the scattering of the covering portion material when the covering portion is formed, and the projections protrude radially inward from the inner circumferential surface of the elastic body and extend along the circumferential direction of the inner circumferential surface.

2. The sealing device according to claim 1, wherein the elastic body includes a first surface which is a part of the inner circumferential surface of the elastic body on which the projection is formed, and a second surface which is located in a first direction along the central axis of the elastic body with respect to the first surface, the portion of the elastic body where the first surface and the second surface intersect forms a lip end which is located radially inward from the projection in a plan view, the covering portion covers the first surface, and the end face of the covering portion in the first direction is located in the same plane as the second surface.

3. The sealing device according to claim 2, further comprising an annular garter spring that presses the outer circumferential surface of the first surface radially inward of the elastic body, wherein the projection is located within the range where the garter spring exists in the axial direction of the central axis of the elastic body.

4. The sealing device according to any one of claims 1 to 3, wherein the elastic body further comprises a dust lip positioned in a second direction opposite to the first direction with respect to the projection.

5. The sealing device according to claim 1, wherein the projection is formed over the entire circumference of the inner surface of the elastic body.

6. The sealing device according to claim 1, wherein the covering portion does not cover the protrusion.

7. The sealing device according to claim 1, which includes a plurality of protrusions including the aforementioned projection, wherein the plurality of protrusions are located at different axial positions relative to the central axis.

8. The sealing device according to claim 1, wherein the elastic body includes a seal lip located in a first direction along the central axis of the elastic body and including a lip end, and a dust lip located in a second direction opposite to the first direction, and the projection is located between the lip end of the seal lip and the dust lip in the axial direction of the central axis.

9. The sealing device according to claim 1, further comprising an annular garter spring that presses the outer circumferential surface of the elastic body radially inward, wherein the projection is formed on the inner circumferential surface of the elastic body within the range in which the garter spring exists in the axial direction of the central axis of the elastic body.

10. A sealing device for sealing an annular gap between the outer circumferential surface of a rotating body and the inner circumferential surface of a housing, comprising: an annular elastic body; a covering portion that covers the inner circumferential surface of the elastic body, has a coefficient of friction lower than that of the elastic body, and contacts the outer circumferential surface of the rotating body, wherein a projection is formed on the inner circumferential surface of the elastic body, the projection protrudes radially inward from the inner circumferential surface of the elastic body and extends along the circumferential direction of the inner circumferential surface, and the covering portion covers the projection.

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