Sealing device

Abstract

This sealing device seals a gap between two members that rotate relatively around an axis. The device is provided with: a metal ring that is fixed to one of the two members and forms an annular shape around the axis; and an elastic body that is supported by the metal ring and forms an annular shape around the axis. The elastic body has an annular base part that is joined to the metal ring, and a cylindrical side lip that protrudes from the base part and contacts the other member of the two members. The outer peripheral surface of the side lip is provided with a plurality of ribs that are spaced apart from each other in the circumferential direction centered on the axis.

Description

sealing device

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

[0002] In sealing devices such as oil seals that seal the gap between two components that rotate relatively around an axis, a side lip may be provided that comes into contact with a rotating flange or other component of one of the two components to improve the ability to prevent foreign matter from entering through the gap.

[0003] For example, the sealing device described in Patent Document 1 has a metal ring and a lip portion that is molded integrally with the metal ring using a rubber-like elastic material. The tip of the lip portion contacts the rotating flange surface as a contacted portion. In Patent Document 1, the relative rotation center of the contacted portion is disposed eccentrically with respect to the rotation center of the flange surface. This suppresses the generation of abnormal noise caused by stick-slip between the flange surface and the contacted portion.

[0004] International Publication No. 2019 / 039152

[0005] In the sealing device described in Patent Document 1, the center of relative rotation of the contacted part of the lip portion is eccentric with respect to the center of rotation of the flange surface, so it is necessary to make structural changes to the flange surface to allow for relative rotation of the contacted part.

[0006] In consideration of the above circumstances, an object of the present disclosure is to easily suppress the generation of abnormal noise caused by stick-slip of a side lip against a rotating counter body.

[0007] In order to solve the above problems, a sealing device according to one embodiment of the present disclosure is a sealing device that seals a gap between two members that rotate relatively around an axis, and includes: a metal ring that is fixed to one of the two members and forms a ring shape around the axis; and an elastic body that is supported by the metal ring and forms a ring shape around the axis, wherein the elastic body has an annular base that is joined to the metal ring and a cylindrical side lip that protrudes from the base and contacts the other of the two members, and the outer peripheral surface of the side lip is provided with a plurality of ribs that are spaced apart from each other in a circumferential direction centered on the axis.

[0008] In the present disclosure, abnormal noise caused by stick-slip of the side lip can be suppressed.

[0009] FIG. 1 is a cross-sectional view of equipment using the sealing device according to the first embodiment. FIG. 2 is a perspective view of a side lip of the sealing device according to the first embodiment. FIG. 3 is a schematic view for explaining frictional vibration of a side lip without ribs. FIG. 4 is a schematic view for explaining the friction state between a side lip without ribs and a mating surface. FIG. 5 is a schematic view for explaining frictional vibration of a side lip with ribs. FIG. 6 is a schematic view for explaining the friction state between a side lip with ribs and a mating surface. FIG. 7 is a perspective view of a side lip of a sealing device according to a second embodiment. FIG. 8 is a diagram showing each condition of Examples 1 to 4 and a comparative example. FIG. 9 is a schematic view of an apparatus for testing abnormal noise of a side lip. FIG. 10 is a diagram showing the results of a squeal confirmation test of Examples 1 to 4 and a comparative example. FIG. 11 is a diagram showing vibration frequency spectra of the side lips of Example 4 and a comparative example.

[0010] Preferred embodiments of the present disclosure will be described below with reference to the accompanying drawings. The dimensions and scale of each part in the drawings may differ from those of the actual parts, and some parts are shown schematically to facilitate understanding. The scope of the present disclosure is not limited to these embodiments unless otherwise specified in the following description to the effect that the present disclosure is limited.

[0011] 1. First Embodiment 1-1. Sealing Device Fig. 1 is a cross-sectional view of a sealing device 10 according to a first embodiment. The sealing device 10 is a structure that seals a gap S between two members 110, 120 that rotate relatively around an axis AX. Fig. 1 illustrates a sealing device 10 that is used in a mechanism such as an automobile differential. Note that the use of the sealing device 10 is not limited to automobile differentials, and may be, for example, differentials used for devices other than automobiles, or various types of transportation equipment, construction equipment, agricultural equipment, and the like other than differentials.

[0012] For ease of explanation, in the following description, one direction along the axis AX will be referred to as the X1 direction, and the direction opposite to the X1 direction will be referred to as the X2 direction. In the following description, the X1 direction and the X2 direction will sometimes be referred to without distinction as the "axial direction." Furthermore, the direction along the circumference of a circle centered on the axis AX will sometimes be referred to as the "circumferential direction." Furthermore, the direction perpendicular to the axis AX will sometimes be referred to as the "radial direction."

[0013] The member 110 is an annular member having an inner peripheral surface 111 centered on the axis AX. The member 110 is, for example, the outer ring of a bearing attached to a housing of a differential gear. Note that the member 110 may be any member having the inner peripheral surface 111, and is not limited to the outer ring of a bearing.

[0014] On the other hand, the member 120 has an outer peripheral surface 121 and a surface 122 centered on the axis AX, and rotates around the axis AX. The member 120 is, for example, a flange provided on a drive shaft. The outer peripheral surface 121 is disposed inside the inner peripheral surface 111 of the member 110. The surface 122 is a surface extending radially outward from the X1-direction end of the outer peripheral surface 121 at a position in the X1 direction relative to the member 110. Here, the surface 122 faces the X2 direction and is a mating surface that contacts the side lip 12d described below. Note that the member 120 may be any member having the surface 122 and having the surface 122 that rotates around the axis AX, and is not limited to a flange provided on a drive shaft. Furthermore, the surface 122 is not limited to a surface parallel to the radial direction, but may be a surface inclined relative to the radial direction or a curved surface.

[0015] In this way, a gap S to be sealed by the sealing device 10 is formed between the inner peripheral surface 111 of the member 110 and the outer peripheral surface 121 of the member 120. The sealing device 10 prevents leakage of fluids such as lubricant from inside the member 110 through the gap S, and prevents entry of foreign matter into the member 110 through the gap S.

[0016] As shown in FIG. 1 , the sealing device 10 has a metal ring 11 fixed to a member 110 and an elastic body 12 fixed to the metal ring 11 .

[0017] The metal ring 11 is fixed to one of the two members 110, 120, the member 110, and is an annular member around the axis line AX. The metal ring 11 is fixed to the member 110, for example, by being fitted onto an inner peripheral surface 111 of the member 110. The metal ring 11 is made of a metal material such as carbon steel, and is formed, for example, by press molding or the like.

[0018] 1, the metal ring 11 has a bent shape when viewed in a cross section cut along a plane including the axis line AX. Specifically, the metal ring 11 has a first portion 11a extending in the axial direction along the inner circumferential surface 111, and a second portion 11b extending radially inward from the end of the first portion 11a in the X1 direction.

[0019] The first portion 11a is cylindrical and has an outer peripheral surface that contacts the inner peripheral surface 111 over the entire circumference. The second portion 11b is annular and is connected to the end of the first portion 11a in the X1 direction over the entire circumference. The inner diameter of the second portion 11b is larger than the diameter of the outer peripheral surface 121 of the member 120. In the example shown in FIG. 1, the second portion 11b has a bent or curved portion when viewed in a cross section cut along a plane including the axis AX. Note that the shape of the second portion 11b is not limited to the example shown in FIG. 1 and may be any shape.

[0020] The elastic body 12 is fixed to the metal ring 11. The elastic body 12 is made of an elastic material such as a rubber material. Examples of such elastic materials include nitrile rubber (NBR), hydrogenated nitrile rubber (H-NBR), acrylic rubber (ACM), and fluororubber (FKM). The elastic body 12 is formed using a molding die. Here, molding is performed with a portion of the metal ring 11 placed in the molding die, thereby obtaining the elastic body 12 fixed to the metal ring 11 by vulcanization adhesion or the like. Note that part or all of the elastic body 12 may be made of a resin material such as a fluororesin such as PTFE (Poly Tetra Fluoro Ethylene).

[0021] The elastic body 12 has a base 12a, lips 12b and 12c, and a side lip 12d, which are integrally formed from the elastic material described above.

[0022] The base 12a is a part of the elastic body 12 and is an annular portion that is joined to the metal ring 11 over the entire circumference. The base 12a is joined to the metal ring 11 by, for example, vulcanization adhesion. In the example shown in Fig. 1 , the base 12a is fixed to the second portion 11b of the metal ring 11. The base 12a also has a portion that is in close contact with the inner circumferential surface 111 over the entire circumference.

[0023] Each of the lips 12b and 12c is a part of the elastic body 12 that protrudes from the base 12a toward the outer peripheral surface 121 of the member 120 and is in contact with the outer peripheral surface 121 over the entire circumference. Here, the lip 12b protrudes from the inner peripheral edge of the base 12a in a direction inclined relative to the radial direction so as to have an X2-direction component. On the other hand, the lip 12c protrudes from the inner peripheral edge of the base 12a in a direction inclined relative to the radial direction so as to have an X1-direction component.

[0024] The shapes of the lips 12b and 12c are not limited to the example shown in Fig. 1 and may be any shape. The lips 12b and 12c may be provided as needed or may be omitted.

[0025] The side lip 12d is a part of the elastic body 12, and is a cylindrical portion that protrudes from the base 12a toward the surface 122 of the member 120, and is in contact with the entire circumference of the surface 122. In this manner, the side lip 12d protrudes from the base 12a and contacts the other of the two members 110, 120, the member 120. Here, the side lip 12d protrudes from the base 12a in a direction having an axial component and a radial component so that its diameter increases in the X1 direction.

[0026] The outer peripheral surface of the side lip 12d is provided with a plurality of ribs 12d1 that are spaced apart from one another in the circumferential direction centered on the axis AX. This makes it possible to suppress the generation of abnormal noise due to stick-slip of the side lip 12d, which will be described later. This point will be described in detail below.

[0027] 2 is a perspective view of the side lip 12d of the sealing device 10 according to the first embodiment. Note that in FIG. 2, portions of the sealing device 10 other than the side lip 12d are omitted from the illustration.

[0028] In the example shown in Fig. 2, eight ribs 12d1 are arranged at equal intervals in the circumferential direction. Each of the ribs 12d1 is provided over the entire area of ​​the side lip 12d in the direction along the axis AX. That is, each rib 12d1 extends from the end E2 of the side lip 12d in the X2 direction to the end E1 of the side lip 12d in the X1 direction. In other words, each rib 12d1 is provided over the entire area from the base 12a to the tip (end E1) of the side lip 12d.

[0029] Each of the ribs 12d1 extends from the base 12a toward the end E1, which is the tip (edge) of the side lip 12d, so as to be inclined in the circumferential direction about the axis AX. That is, each rib 12d1 extends in a direction inclined at an inclination angle θ with respect to the axial direction when viewed in the radial direction. The inclination direction is oriented in the direction of rotation of the member 120, from the end E2, which is the base end of the side lip 12d, toward the end E1.

[0030] The number of ribs 12d1 provided on the side lip 12d is determined depending on the width W and height h, and is not limited to the example shown in Fig. 2. However, from the viewpoint of suitably suppressing the generation of abnormal noise due to stick-slip of the side lip 12d, which will be described later, under the following suitable inclination angle θ, width W, and height h, the number is preferably 4 to 15, and more preferably 6 to 12.

[0031] The inclination angle θ of each of the plurality of ribs 12d1 with respect to the axis AX is preferably 30° to 80°, more preferably 40° to 70°, and even more preferably 40° to 60°. By setting the inclination angle θ within this range, the direction of the frictional force of the side lip 12d with respect to the other member 120 can be suitably shifted in the rotational direction, as will be described later. As a result, the generation of abnormal noise due to stick-slip of the side lip 12d with respect to the surface 122, as will be described later, can be suitably suppressed.

[0032] The width W of each of the plurality of ribs 12d1 is greater than the height h of each of the plurality of ribs 12d1. Therefore, even if the side lip 12d is provided with the ribs 12d1, the pressing reaction force of the ribs 12d1 of the side lip 12d against the other member 120 can be reduced. As a result, as will be described later, the surface pressure of the side lip 12d against the other member 120 can be reduced while the direction of the frictional force of the side lip 12d against the other member 120 can be shifted in the rotational direction. As a result, abnormal noise caused by stick-slip of the side lip 12d against the other member 120 can be suitably suppressed.

[0033] Here, the width W of each rib 12d1 is more preferably 2 to 5 times the height h. In this case, the generation of abnormal noise due to stick-slip of the side lip 12d, which will be described later, can be suitably suppressed.

[0034] When the thickness of the side lip 12d excluding the ribs 12d1 is t and the height of each of the ribs 12d1 is h, the ratio h / t is preferably 0.5 to 1.5. In this case, even if the side lip 12d is provided with the ribs 12d1, the pressing reaction force of the ribs 12d1 of the side lip 12d against the other member 120 can be reduced. This reduces the surface pressure of the side lip 12d against the other member 120 while shifting the direction of the frictional force of the side lip 12d against the other member 120 in the rotational direction. As a result, noise caused by stick-slip of the side lip 12d against the other member 120 can be effectively suppressed.

[0035] The height h of each rib 12d1 is not particularly limited, but is preferably 0.5 to 1.5 times the thickness t of the side lip 12d excluding the rib 12d1, in which case noise due to stick-slip of the side lip 12d, as described below, can be effectively suppressed.

[0036] 1-3. Side Lip and Counterpart Surface Figure 3 is a schematic diagram illustrating the frictional vibration of the side lip 12dX without the rib 12d1. Figure 4 is a schematic diagram illustrating the frictional state between the side lip 12dX without the rib 12d1 and the counterpart surface 122. The side lip 12dX is configured similarly to the above-described side lip 12d, except that the rib 12d1 is omitted. In Figure 3, the side lip 12dX that contacts the surface 122 of the member 120 that rotates around the axis AX is represented by a one-degree-of-freedom model with mass m and spring constant k.

[0037] As shown in Figure 3, when the member 120 rotates around the axis AX, a frictional force F is generated between the side lip 12dX and the surface 122 of the member 120 in the tangential direction of the circumference centered on the axis AX. As a result, the side lip 12dX is twisted by the frictional force F, and a restoring force kx about the axis AX acts on the side lip 12dX to resist this twisting. Here, as the member 120 rotates around the axis AX, the tip of the side lip 12dX is displaced by an amount x relative to the surface 122. The direction of this displacement is the tangential direction of the circumference centered on the axis AX.

[0038] 4, the direction of the relative displacement velocity x' of the tip of the side lip 12dX with respect to the surface 122 is parallel to the direction of the rotational drive velocity V of the surface 122. Therefore, the direction of the restoring force kx is opposite to the direction of the friction force F. Therefore, when the coefficient of friction of the side lip 12dX decreases as the rotational drive velocity V increases, noise caused by stick-slip with respect to the surface 122 is likely to occur.

[0039] Fig. 5 is a schematic diagram illustrating frictional vibration of the side lip 12d having the rib 12d1. Fig. 6 is a schematic diagram illustrating the frictional state between the side lip 12d having the rib 12d1 and the mating surface 122. In Fig. 5, the side lip 12d in contact with the surface 122 of the member 120 rotating about the axis line AX is represented by a one-degree-of-freedom model with a mass m and a spring constant k.

[0040] As shown in Figure 5, when the member 120 rotates about the axis AX, a frictional force F is generated between the side lip 12d and the surface 122 of the member 120 in the tangential direction of the circumference centered on the axis AX. As a result, the side lip 12d is twisted by the frictional force F, and a restoring force kx about the axis AX acts on the side lip 12d to resist this twisting. Furthermore, as the member 120 rotates about the axis AX, the tip of the side lip 12d is displaced by an amount x relative to the surface 122. Due to the influence of the rib 12d1, the direction of this displacement is inward of the tangential direction of the circumference centered on the axis AX.

[0041] As shown in FIG. 6 , the direction of the relative displacement velocity x′ of the tip of the side lip 12d relative to the surface 122 is inward of the direction of the rotational drive velocity V of the surface 122. Therefore, the direction of the restoring force kx is non-parallel to the direction of the frictional force F and is inclined at a misalignment angle β with respect to the direction of the rotational drive velocity V. Furthermore, the direction of the frictional force F is inclined at an angle α with respect to the direction of the restoring force kx. This reduces the effective frictional force of the side lip 12d relative to the surface 122. As a result, even if the coefficient of friction of the side lip 12d decreases as the rotational drive velocity V increases, noise caused by stick-slip with respect to the surface 122 is unlikely to occur.

[0042] As described above, in the sealing device 10, the side lip 12d is provided on its outer peripheral surface with a plurality of ribs 12d1 spaced apart from one another in the circumferential direction about the axis AX, thereby locally increasing the rigidity of the side lip 12d at a plurality of locations in the circumferential direction of the side lip 12d, and therefore the direction of the frictional force of the side lip 12d against the other member 120 can be shifted in the rotational direction. As a result, abnormal noise caused by stick-slip of the side lip 12d against the other member 120 can be suppressed without making any structural changes or the like due to eccentricity between the two members 110, 120.

[0043] As described above, each of the ribs 12d1 extends in a circumferential direction inclined about the axis AX from the base 12a toward the end E1, which is the tip of the side lip 12d. This reduces the pressing reaction force of the ribs 12d1 of the side lip 12d against the other member 120. As a result, even if the ribs 12d1 are provided on the side lip 12d, the surface pressure of the side lip 12d against the other member 120 can be reduced while shifting the direction of the frictional force of the side lip 12d against the other member 120 in the rotational direction. As a result, noise caused by stick-slip of the side lip 12d against the other member 120 can be effectively suppressed.

[0044] As described above, each of the ribs 12d1 is provided over the entire area of ​​the side lip 12d in the direction along the axis AX, so that the direction of the frictional force of the side lip 12d with respect to the other member 120 can be suitably shifted in the rotational direction.

[0045] 2. Second Embodiment A second embodiment of the present disclosure will be described below. In the following exemplary embodiment, for elements whose actions and functions are similar to those of the above-described embodiment, the reference numerals used in the description of the above-described embodiment will be used, and detailed descriptions of each element will be omitted as appropriate.

[0046] Fig. 7 is a perspective view of a side lip 12e of a sealing device 10A according to the second embodiment. The sealing device 10A is configured similarly to the sealing device 10 of the first embodiment, except that it includes an elastic body 12A instead of the elastic body 12 of the first embodiment. The elastic body 12A is configured similarly to the elastic body 12 of the first embodiment, except that it includes a side lip 12e instead of the side lip 12d of the first embodiment. Note that Fig. 7 omits illustration of portions of the sealing device 10A other than the side lip 12e.

[0047] The side lip 12e is configured similarly to the side lip 12d of the first embodiment, except that it has a plurality of first ribs 12e1 and a plurality of second ribs 12e2 as the plurality of ribs instead of the plurality of ribs 12d1 of the first embodiment.

[0048] 7, three first ribs 12e1 are arranged at equal intervals in the circumferential direction, and three second ribs 12e2 are arranged at equal intervals in the circumferential direction, so that the first ribs 12e1 and the second ribs 12e2 are alternately arranged in the circumferential direction. Each first rib 12e1 is provided over the entire axial area of ​​the side lip 12e. Similarly, each second rib 12e2 is provided over the entire axial area of ​​the side lip 12e.

[0049] Here, each first rib 12e1 extends in a direction inclined at an inclination angle θ1 relative to the axial direction when viewed radially. In contrast, each second rib 12e2 extends in a direction inclined at an inclination angle θ2 relative to the axial direction when viewed radially. In other words, the first rib 12e1 and the second rib 12e2 are inclined in opposite directions in the circumferential direction.

[0050] The number of first ribs 12e1 and second ribs 12e2 provided on the side lip 12e is determined according to the width W and height h, and is not limited to the example shown in Fig. 7. However, from the viewpoint of suitably suppressing the generation of noise due to stick-slip of the side lip 12e under the following suitable inclination angles θ1, θ2, etc., the number is preferably 2 to 8, more preferably 2 to 6. Furthermore, the number of first ribs 12e1 and the number of second ribs 12e2 may be different from each other, but are preferably equal to each other from the viewpoint of suitably suppressing the generation of noise due to stick-slip of the side lip 12e.

[0051] As described above, each of the first ribs 12e1 extends from the base 12a toward the tip of the side lip 12d, tilting in one direction in the circumferential direction about the axis AX. In contrast, each of the second ribs 12e2 extends from the base 12a toward the tip of the side lip 12d, tilting in the other direction in the circumferential direction about the axis AX. By using such a plurality of first ribs 12e1 and a plurality of second ribs 12e2, it is possible to suppress abnormal noise caused by stick-slip of the side lip 12e relative to the other member 120, regardless of the relative rotation direction of the two members 110, 120.

[0052] The inclination angle θ1 of each of the plurality of first ribs 12e1 with respect to the axis AX is preferably 30° or greater and 80° or less. Similarly, the inclination angle θ2 of each of the plurality of second ribs 12e2 with respect to the axis AX is preferably 30° or greater and 80° or less. By having the inclination angles θ1 and θ2 within such ranges, the direction of the frictional force of the side lip 12e with respect to the other member 120 can be suitably shifted in the rotational direction. Note that the inclination angles θ1 and θ2 may be different from each other, but are preferably equal to each other from the viewpoint of suitably suppressing the generation of abnormal noise due to stick-slip of the side lip 12e, which will be described later.

[0053] According to the second embodiment described above, noise caused by stick-slip of the side lip can also be suppressed.

[0054] 3. Modifications The above-described embodiments may be modified in various ways. Specific modifications that may be applied to the above-described embodiments are exemplified below. Two or more embodiments arbitrarily selected from the following examples may be combined as appropriate within the scope of not mutually contradictory.

[0055] 3-1. Modification 1 In the above-described embodiment, the ribs provided on the side lip extend in a direction inclined relative to the axial direction as viewed in the radial direction, but the present invention is not limited to this, and the ribs may extend in a direction parallel to the axial direction as viewed in the radial direction.

[0056] 3-2. Modification 2 In the second embodiment described above, a configuration in which the plurality of first ribs 12e1 and the plurality of second ribs 12e2 do not intersect with each other is exemplified, but this is not limiting, and the plurality of first ribs 12e1 and the plurality of second ribs 12e2 may intersect with each other.

[0057] 3-3. Modification 3 In the above-described embodiment, an example is given in which the widths and thicknesses of the plurality of ribs are equal to each other, but this is not limiting, and the widths and thicknesses of the plurality of ribs may be different from each other.

[0058] 3-4. Modification 4 In the above-described embodiment, an example is given in which the multiple ribs are arranged at equal intervals in the circumferential direction, but the present invention is not limited to this example, and the multiple ribs do not have to be arranged at equal intervals in the circumferential direction.

[0059] 3-5. Modification 5 In the above-described embodiment, the rigidity of the side lip is locally increased at multiple locations around the circumferential direction of the side lip by providing multiple ribs aligned in the circumferential direction on the side lip. However, the present invention is not limited to this, and any other configuration may be used as long as the rigidity of the side lip can be locally varied at multiple locations around the circumferential direction of the side lip. For example, the rigidity of the side lip can be locally varied at multiple locations around the circumferential direction of the side lip by providing grooves or using materials with different elastic moduli at multiple locations around the circumferential direction of the side lip.

[0060] 4. Supplementary Notes The following aspects, for example, can be understood from the above embodiment and modified examples.

[0061] A sealing device of a first aspect, which is a preferred example of the present disclosure, is a sealing device that seals a gap between two members that rotate relatively around an axis, and comprises: a metal ring fixed to one of the two members and forming a ring shape around the axis; and an elastic body supported by the metal ring and forming a ring shape around the axis, wherein the elastic body has an annular base joined to the metal ring and a cylindrical side lip that protrudes from the base and contacts the other of the two members, and the outer peripheral surface of the side lip is provided with a plurality of ribs that are arranged at intervals from each other in the circumferential direction centered on the axis.

[0062] In the first aspect described above, the outer peripheral surface of the side lip is provided with a plurality of ribs spaced apart from one another in the circumferential direction about the axis, which allows the direction of the frictional force of the side lip against the other component to be shifted in the rotational direction, thereby easily suppressing noise caused by stick-slip of the side lip against the other component without requiring structural modifications to accommodate eccentricity between the two components.

[0063] In a second aspect, which is a preferred example of the first aspect, each of the plurality of ribs extends at an inclination in the circumferential direction about the axis as it moves from the base toward the tip of the side lip. The second aspect described above reduces the pressing reaction force of the ribs on the side lip against the other component. This allows the frictional force of the side lip against the other component to be shifted in the rotational direction while reducing the surface pressure of the side lip against the other component, even when the side lip is provided with ribs. As a result, noise caused by stick-slip of the side lip against the other component can be effectively suppressed.

[0064] In a third aspect, which is a preferred example of the second aspect, the plurality of ribs include a plurality of first ribs extending from the base toward the tip of the side lip so as to be inclined in one circumferential direction about the axis, and a plurality of second ribs extending from the base toward the tip of the side lip so as to be inclined in the other circumferential direction about the axis. In the third aspect described above, it is possible to suppress abnormal noise caused by stick-slip of the side lip relative to the other member, regardless of the relative rotation direction of the two members.

[0065] In a fourth aspect, which is a preferred example of the second or third aspect, the inclination angle of each of the plurality of ribs with respect to the axis is 30° to 80°. In the fourth aspect, the direction of the frictional force of the side lip with respect to the other member can be suitably shifted in the rotational direction.

[0066] In a fifth aspect, which is a preferred example of any of the first to fourth aspects, each of the plurality of ribs is provided over the entire area of ​​the side lip in the direction along the axis, so that the direction of the frictional force of the side lip against the other member can be suitably shifted in the rotational direction.

[0067] In a sixth aspect, which is a preferred example of any of the first to fifth aspects, the width of each of the plurality of ribs is greater than the height of each of the plurality of ribs. In the sixth aspect, even if ribs are provided on the side lip, the pressing reaction force of the ribs on the other component can be reduced. This reduces the surface pressure of the side lip on the other component while shifting the direction of the frictional force of the side lip on the other component in the rotational direction. As a result, noise caused by stick-slip of the side lip on the other component can be effectively suppressed.

[0068] In a seventh aspect, which is a preferred example of any of the first to sixth aspects, where t is the thickness of the side lip excluding the ribs and h is the height of each of the ribs, h / t is 0.5 to 1.5. In the seventh aspect, even if the side lip is provided with ribs, the pressing reaction force of the ribs on the other component can be reduced. This reduces the surface pressure of the side lip on the other component while shifting the direction of the frictional force of the side lip against the other component in the rotational direction. As a result, noise caused by stick-slip of the side lip against the other component can be effectively suppressed.

[0069] Examples of the present invention will be described below in detail, but the present invention is not limited to the following examples.

[0070] A. Manufacturing of the Sealing Device Fig. 8 is a diagram showing the conditions for Examples 1 to 4 and the Comparative Example. The sealing device having the side lip 12d shown in Fig. 2 was manufactured under the conditions shown in Fig. 8.

[0071] In FIG. 8, "Number of ribs" is the number of ribs 12d1, "Rib width" is the width W of rib 12d1, "Rib height" is the height h of rib 12d1, "Rib angle" is the inclination angle θ of rib 12d1, and "Rate of change in pressing reaction force" is the ratio of the reaction force when pressed against surface 210 described below, based on a comparative example.

[0072] Specifically, in Example 1, the number of ribs 12d1 is 8, the width W of the ribs 12d1 is 2 mm, the height h of the ribs 12d1 is 1 mm, and the inclination angle θ of the ribs 12d1 is 0°. The rate of change in pressing reaction force in Example 1 was +10.7%.

[0073] In Example 2, a sealing device was manufactured in the same manner as in Example 1, except that the width W of the rib 12d1 was set to 5 mm. The pressing reaction force change rate in Example 2 was +34.9%.

[0074] In Example 3, a sealing device was manufactured in the same manner as in Example 1, except that the inclination angle θ was set to 45°. The rate of change in pressing reaction force in Example 3 was +0.3%.

[0075] In Example 4, a sealing device was manufactured in the same manner as in Example 2, except that the inclination angle θ was set to 45°. That is, in Example 4, a sealing device was manufactured in the same manner as in Example 1, except that the width W of the rib 12d1 was set to 5 mm and the inclination angle θ was set to 45°. The pressing reaction force change rate in Example 4 was +20.5%.

[0076] In the comparative example, a sealing device was manufactured in the same manner as in Example 1, except that the rib 12d1 was omitted.

[0077] B. Abnormal Noise Test Figure 9 is a schematic diagram of an apparatus for testing the side lip 12d for abnormal noise. As shown in Figure 9, the apparatus includes a rotating plate 200 and a laser vibrometer 300. The rotating plate 200 has a surface 210 perpendicular to the axis AX and rotates around the axis AX. The tip of the side lip of each example or comparative example comes into contact with the surface 210. The laser vibrometer 300 measures the vibration of the side lip.

[0078] In the abnormal noise test, vibrations were measured with a laser vibrometer 300 for each side lip of Examples 1 to 4 and the Comparative Example, and the presence or absence of abnormal noise (squeak) was determined by listening to the sound under the following conditions: Material of surface 210: SPCC Surface roughness Ra of surface 210: 0.36 μm Rotation speed of surface 210: 50 rpm to 100 rpm Properties of surface 210: Dry

[0079] FIG. 10 is a diagram showing the results of the squeal confirmation test for Examples 1 to 4 and the Comparative Example. In FIG. 10, "P" indicates that no abnormal noise was generated, and "F" indicates that abnormal noise was generated. As shown in FIG. 10, in all of Examples 1 to 4, no abnormal noise was generated over a rotation speed of the surface 210 ranging from 50 rpm to 100 rpm. In contrast, in the Comparative Example, abnormal noise was generated over a rotation speed of the surface 210 ranging from 50 rpm to 100 rpm.

[0080] 11 is a diagram showing the vibration frequency spectra of the side lips of Example 4 and the comparative example, in which the vibration frequency spectrum A of Example 4 is shown by a solid line and the vibration frequency spectrum B of the comparative example is shown by a dashed line.

[0081] 11, in Example 4, vibrations occurred at extremely low frequencies, but almost no vibrations occurred over a wide range of frequencies, whereas in the Comparative Example, vibrations occurred over a wide range of frequencies.

[0082] DESCRIPTION OF SYMBOLS 10...Sealing device, 10A...Sealing device, 11...Metal ring, 11a...First part, 11b...Second part, 12...Elastic body, 12A...Elastic body, 12a...Base, 12b...Lip, 12c...Lip, 12d...Side lip, 12d1...Rib, 12dX...Side lip, 12e...Side lip, 12e1...First rib, 12e2...Second rib, 110...Member, 111...Inner peripheral surface, 120...Member, 121...Outer peripheral surface, 122...Surface , 200...rotating plate, 210...surface, 300...laser vibrometer, A...vibration frequency spectrum, AX...axis, B...vibration frequency spectrum, E1...edge, E2...edge, F...friction force, S...gap, V...rotational drive speed, W...width, h...height, k...spring constant, kx...restoring force, m...mass, t...thickness, x...displacement amount, x'...displacement speed, α...angle, β...misalignment angle, θ...tilt angle, θ1...tilt angle, θ2...tilt angle.

Claims

1. A sealing device for sealing a gap between two components which rotate relatively about an axis, comprising: a metal ring fixed to one of the two components and forming an annular shape about the axis; and an elastic body supported by the metal ring and forming an annular shape about the axis, wherein the elastic body has an annular base joined to the metal ring, and a cylindrical side lip protruding from the base and contacting the other of the two components, and the outer peripheral surface of the side lip is provided with a plurality of ribs arranged at intervals from each other in the circumferential direction centered on the axis.

2. The sealing device according to claim 1, wherein each of the plurality of ribs extends at an incline in the circumferential direction from the base portion toward the tip of the side lip.

3. A sealing device as described in claim 2, wherein the plurality of ribs include: a plurality of first ribs extending from the base toward the tip of the side lip, inclining in one circumferential direction about the axis; and a plurality of second ribs extending from the base toward the tip of the side lip, inclining in the other circumferential direction about the axis.

4. The sealing device according to claim 2, wherein the inclination angle of each of the plurality of ribs with respect to the axis is greater than or equal to 30° and less than or equal to 80°.

5. The sealing device according to claim 2, wherein each of the plurality of ribs is provided over the entire area from the base to the tip of the side lip.

6. The sealing device according to claim 1, wherein the width of each of the plurality of ribs is greater than the height of each of the plurality of ribs.

7. The sealing device according to claim 1, wherein, when the thickness of the side lip excluding the plurality of ribs is t and the height of each of the plurality of ribs is h, h / t is 0.5 or more and 1.5 or less.

Images