Sealing device

Abstract

A seal device is arranged between an inner member and an outer member that relatively rotate. The seal device has a first seal member and a second seal member. The first seal member has a cylindrical portion attached to the outer member and a lip. The second seal member has a sleeve into which the inner member is inserted and a flange that expands radially outward from the sleeve, the flange having a rigid flange portion made of a rigid material that is joined to the sleeve and a circular ring-shaped elastic flange portion that is in close contact with the rigid flange portion. An annular protrusion that contacts an outer peripheral surface of the inner member is formed on an inner periphery of the elastic flange portion. In an initial state, an inner peripheral surface of the protrusion has a cylindrical portion. An inner diameter of the cylindrical portion in the initial state is smaller than an inner diameter of the sleeve. A length of the cylindrical portion of the protrusion in the initial state is 0.15 mm or more.

Description

TECHNICAL FIELD

[0001] The present application relates to a sealing device. BACKGROUND

[0002] A rolling bearing that supports an axle of a vehicle is provided in a wheel hub of the vehicle. The rolling bearing is called a wheel hub bearing. A sealing device is provided between an inner ring and an outer ring of the wheel hub bearing. The sealing device seals lubricant (grease) inside the bearing and prevents foreign matter such as water, dust, and the like from intruding from the outside into the inside of the bearing.

[0003] In a sealing device provided in a wheel hub bearing, there is a device that is composed of two sealing members (Patent Literature 1). One sealing member is attached to an outer side member such as an outer ring, and the other sealing member is attached to an inner side member such as an inner ring. One of the sealing members is provided with a lip that is capable of slidingly contacting the other sealing member, and the lip prevents leakage of lubricant.

[0004] The sealing member attached to the inner side member has a sleeve into which the inner side member is inserted, and a flange that expands radially outward from the sleeve. The flange of the sealing member described in Patent Literature 1 has a flange portion made of metal and an elastic flange portion made of an elastic material.

[0005] PRIOR ART DOCUMENTS

[0006] PATENT LITERATURE

[0007] Patent Literature 1: Japanese Patent Application Publication No. 2017-190804 SUMMARY

[0008] The sleeve of the sealing member described above and the inner side member that is inserted into the sleeve are made of a rigid material, and a slight gap is generated between the two. In order to ensure the sealing property of the internal space that is closed by the sealing device, it is desirable that the inner peripheral portion of the elastic flange portion described above is in close contact with the inner side member.

[0009] In addition, in a case where a high load is applied to the wheel hub bearing, the pressure of the internal space of the bearing increases. It is desirable that even in this case, a gap is not generated between the inner peripheral portion of the elastic flange portion and the outer peripheral surface of the inner side member, and the sealing property of the internal space is maintained.

[0010] Therefore, the present application provides a sealing device that is capable of maintaining the sealing property of an internal space.

[0011] A sealing device according to one aspect of the present invention is disposed between an inner member and an outer member that rotate relative to each other, and seals the gap between the inner member and the outer member. The sealing device includes a first sealing member having a cylindrical portion mounted on the outer member, an annular portion extending radially inward from the cylindrical portion, and a lip extending from the annular portion; and a second sealing member having a cylindrical sleeve into which the inner member is inserted, and a flange extending radially outward from the sleeve, the flange being opposite the annular portion of the first sealing member, and the lip of the first sealing member being slidably in contact with the sleeve. The sleeve of the second sealing member is formed of a rigid material. The flange of the second sealing member has a rigid flange portion made of the rigid material connected to the sleeve and an annular elastic flange portion made of an elastic material that is in close contact with the rigid flange portion. An annular protrusion is formed on the inner periphery of the elastic flange portion, contacting the outer peripheral surface of the inner member. In its initial state, the inner circumferential surface of the protrusion has a cylindrical portion and two truncated conical inclined surface portions adjacent to the cylindrical portion. In the initial state, the inner diameter of the cylindrical portion is smaller than the inner diameter of the sleeve. In the initial state, the length of the cylindrical portion of the protrusion is 0.15 mm or more.

[0012] In this configuration, because the length of the cylindrical portion of the protrusion formed on the inner circumference of the elastic flange of the second sealing member is 0.15 mm or more in the initial state, even if the pressure in the internal space sealed by the sealing device increases, a gap is unlikely to form between the protrusion of the elastic flange and the outer circumferential surface of the cylindrical portion of the inner member. Therefore, the sealing performance of the internal space sealed by the sealing device is maintained. Attached Figure Description

[0013] Figure 1 This is a partial cross-sectional view of an example of a rolling bearing used in the sealing device according to an embodiment of the present invention.

[0014] Figure 2 This is a partial cross-sectional view of the sealing device according to an embodiment of the present invention.

[0015] Figure 3 yes Figure 2 A magnified view of a portion of the image.

[0016] Figure 4 It is the elastic flange that protrudes due to the deformation of the inner component, and... Figure 3 The same enlarged image.

[0017] Figure 5 This is a partially enlarged cross-sectional view of the sealing device of the comparative example. Detailed Implementation

[0018] The following is a reference to the attached document. Figure 1The embodiments of the present invention will be described below. The scale of the accompanying drawings may not be accurate, and sometimes some features may be enlarged or omitted.

[0019] Figure 1 An example of a rolling bearing used in the sealing device of the present invention is a wheel hub bearing for motor vehicles. However, the application of the present invention is not limited to wheel hub bearings; it can also be applied to other rolling bearings. Furthermore, although the wheel hub bearing described below is a ball bearing, the application of the present invention is not limited to ball bearings; it can also be applied to other rolling bearings such as roller bearings and needle roller bearings having other types of rolling elements. Additionally, the present invention can also be applied to rolling bearings used in machinery other than motor vehicles.

[0020] The wheel hub bearing 1 includes: a wheel hub 4 having a hole 2 for inserting an axle (not shown); an inner ring (inner component) 6 mounted on the wheel hub 4; an outer ring (outer component) 8 disposed on the outside of these components; a plurality of balls 10 arranged in a row between the wheel hub 4 and the outer ring 8; a plurality of balls 12 arranged in a row between the inner ring 6 and the outer ring 8; and a plurality of retainers 14 and 15 for holding these balls in a specified position.

[0021] The outer ring 8 is fixed, while the hub 4 and the inner ring 6 rotate along with the rotation of the axle.

[0022] The common central axis Ax of the axle and wheel hub bearing 1 along Figure 1 It extends in the vertical direction. Figure 1 In the diagram, only the left portion is shown relative to the central axis Ax. Although no detailed illustration is provided, Figure 1 The upper side is the outer side (external side) where the wheels of the motor vehicle are mounted, and the lower side is the inner side (internal side) where differential gears and the like are mounted. Figure 1 The outer and inner sides shown refer to the outer and inner sides of the radial direction, respectively.

[0023] The outer ring 8 of the hub bearing 1 is fixed to the hub steering knuckle 16. The hub 4 has an outer side flange 18 that extends radially outward from the outer ring 8. The wheel can be mounted to the outer side flange 18 using hub bolts 19.

[0024] A sealing device 20 is disposed near the outer end of the outer ring 8 to seal the gap between the outer ring 8 and the hub 4, and a sealing device 21 is disposed on the inner side of the inner end of the outer ring 8 to seal the gap between the outer ring 8 and the inner ring 6. These sealing devices 20 and 21 prevent the outflow of grease, i.e., lubricant, from the internal space of the hub bearing 1, and prevent the inflow of foreign matter (including water (including muddy water or salt water) and dust) into the internal space of the hub bearing 1. Figure 2In the image, arrow F illustrates an example of the direction of flow from external foreign matter.

[0025] The sealing device 20 is disposed between the rotating hub 4 of the hub bearing 1 and the cylindrical end 8A on the outer side of the fixed outer ring 8, and seals the gap between the hub 4 and the outer ring 8. The sealing device 21 is disposed between the rotating inner ring 6 of the hub bearing 1 and the inner end 8B on the inner side of the fixed outer ring 8, and seals the gap between the inner ring 6 and the outer ring 8.

[0026] like Figure 2 As shown, the sealing device 21 is disposed within the gap between the end 8B of the outer ring 8 of the hub bearing 1 and the inner ring 6 of the hub bearing 1. Although the sealing device 21 is annular, Figure 2 Only the left side is shown. From Figure 2 It is obvious that the sealing device 21 has a composite structure including a first sealing member 30 and a second sealing member 40.

[0027] The first sealing member 30 is a fixed sealing member installed on the outer ring 8 and not rotating. The first sealing member 30 is a composite structure having an elastic ring 31 and a rigid ring 32. The elastic ring 31 is formed of an elastic material, such as an elastomer. The rigid ring 32 is formed of a rigid material, such as a metal, and reinforces the elastic ring 31. The rigid ring 32 has a generally L-shaped cross-sectional shape. A portion of the rigid ring 32 is embedded in the elastic ring 31 and is in close contact with the elastic ring 31.

[0028] The first sealing member 30 has a cylindrical portion 33, an annular portion 34, radial lips 35 and 36, and side lips 37 and 38.

[0029] The cylindrical portion 33 forms a mounting portion installed on the outer ring 8. Specifically, the cylindrical portion 33 is inserted (i.e., pressed into) the end 8B of the outer ring 8 in an interference fit manner. The annular portion 34 is annular in shape and is disposed radially inward of the cylindrical portion 33, extending towards the inner ring 6 and radially inward. The annular portion 34 has a thinner portion located radially inward and a thicker portion located radially outward. The cylindrical portion 33 and the annular portion 34 are composed of a rigid ring 32 and an elastic ring 31.

[0030] Radial lips 35 and 36 extend radially inward from the inner end of the annular portion 34, and the front ends of radial lips 35 and 36 contact the sleeve 42A of the second sealing member 40. Radial lips 35 and 36 are formed by elastic rings 31.

[0031] Side lip 37 extends from the thinner portion of the annular portion 34 toward the inner side. Side lip 38 extends from the thicker portion of the annular portion 34 toward the inner side. The front ends of side lips 37 and 38 contact the rigid flange portion 42B of the second sealing member 40. Side lips 37 and 38 are formed by elastic rings 31.

[0032] The second sealing member 40 can also be called an oil slinger ring or a rotary sealing member. The second sealing member 40 is installed on the inner ring 6. When the inner ring 6 rotates, the second sealing member 40 rotates together with the inner ring 6, causing foreign objects flying in from the outside to splash.

[0033] In this embodiment, the second sealing member 40 is also a composite structure having an elastic ring 41 and a rigid ring 42. The rigid ring 42 is formed of a rigid material, such as metal.

[0034] The rigid ring 42 has a generally L-shaped cross-sectional shape. Specifically, the rigid ring 42 includes a cylindrical sleeve 42A and an annular rigid flange 42B extending radially outward from the sleeve 42A. The sleeve 42A constitutes a mounting portion for mounting on the inner ring 6. Specifically, the end of the inner ring 6 is inserted (i.e., pressed into) the sleeve 42A in an interference fit manner.

[0035] The rigid flange portion 42B is disposed radially outward of the sleeve 42A, extends radially outward, and is opposite to the annular portion 34 of the first sealing member 30. In this embodiment, the rigid flange portion 42B is a flat plate located in a plane perpendicular to the axis of the sleeve 42A.

[0036] The elastic ring 41 is in close contact with the rigid flange 42B of the rigid ring 42. In this embodiment, the elastic ring 41 is provided for measuring the rotational speed of the inner ring 6. Specifically, the elastic ring 41 is formed of an elastomeric material containing magnetic metal powder and ceramic powder, and has multiple S poles and N poles due to the magnetic metal powder. In the elastic ring 41, multiple S poles and N poles are alternately arranged at equal angular intervals in the circumferential direction. The rotational angle of the elastic ring 41 can be measured using a magnetic sensor (not shown). Therefore, the magnetic sensor and the elastic ring 41 constitute a magnetic rotary encoder.

[0037] The elastic ring 41 and the rigid flange portion 42B engage with each other and can be regarded as forming a flange 44. Therefore, the elastic ring 41 can be referred to as the elastic flange portion 45, and the flange 44 can be regarded as having a rigid flange portion 42B made of rigid material connected to the sleeve 42A, and an annular elastic flange portion 45 made of elastic material that is in close contact with the rigid flange portion 42B.

[0038] The radial lip 35 of the first sealing member 30 is a grease lip. The grease lip 35 mainly serves to prevent lubricant from flowing out of the internal space of the hub bearing 1. The radial lip 36 is a dustproof lip. The dustproof lip 36 mainly serves to prevent foreign objects from flowing into the internal space of the hub bearing 1 from the outside. The side lips 37 and 38 serve to prevent foreign objects from flowing into the radial lip 36 from the outside.

[0039] The first sealing member 30 is installed on the fixed outer ring 8. On the other hand, due to the rotation of the inner ring 6 and the second sealing member 40, the radial lips 35 and 36 slide relative to the sleeve 42A of the second sealing member 40, and the side lips 37 and 38 slide relative to the rigid flange 42B of the second sealing member 40.

[0040] An annular protrusion 50 is formed on the inner periphery of the elastic flange portion 45, contacting the outer peripheral surface of the inner ring 6. In the undeformed state (initial state) of the elastic flange portion 45, the inner peripheral surface of the protrusion 50 has a cylindrical portion 52 and two truncated conical inclined surface portions 53 and 54 adjacent to the cylindrical portion 52. In the initial state, the cylindrical portion 52 extends linearly along the axial direction of the second sealing member 40 when viewed from a direction perpendicular to the axis of the second sealing member 40. The inclined surface portion 53 is located on the internal space side of the cylindrical portion 52, and the inclined surface portion 54 is located on the atmospheric side of the cylindrical portion 52 (between the cylindrical portion 52 and the end face 45a of the elastic flange portion 45).

[0041] exist Figure 2 In the diagram, the inner ring 6 and the outer ring 8 are depicted with dashed lines. Because the cylindrical portion 33 of the first sealing member 30 is embedded in the outer ring 8, the cylindrical portion 33 deforms, and the cylindrical portion 33 is actually located at a position greater than... Figure 2 The position is located radially inward. Furthermore, because the inner ring 6 is embedded in the sleeve 42A and the elastic flange 45 of the second sealing member 40, the sleeve 42A and the elastic flange 45 (especially the protrusion 50) deform, and the sleeve 42A and the elastic flange 45 are actually larger than... Figure 2 It is located on the radially outer side.

[0042] so, Figure 3 The sleeve 42A and the elastic flange 45 are shown in their initial, undeformed state. Figure 4 The sleeve 42A and the elastic flange 45 in this initial state are shown in magnification. Figure 3 Is with Figure 4 The same enlarged view shows the elastic flange 45 (especially the protrusion 50) that deforms upon contact with the inner ring 6, with solid lines, and the protrusion 50 in its initial state, with dashed lines.

[0043] The sleeve 42A and the inner ring 6 of the embedded sleeve 42A are made of rigid material, which will create a small gap between them. In order to ensure the sealing of the internal space sealed by the sealing device 21, it is desirable that the inner circumferential portion of the elastic flange 45 is in close contact with the inner ring 6.

[0044] Furthermore, when a high load is applied to the hub bearing 1, the pressure inside the hub bearing 1 increases. In this case, due to the high pressure inside the hub bearing 1, leakage L of air or lubricant from the hub bearing 1 occurs (see reference). Figure 3The gap between the inner circumferential portion of the elastic flange 45 and the outer circumferential surface of the inner ring 6 is undesirable. On the other hand, when the temperature of the wheel bearing 1 drops (e.g., when the vehicle stops moving), the pressure inside the wheel bearing 1 decreases. If there is a leak L of air or lubricant from the internal space, the pressure inside the wheel bearing 1 becomes extremely low when the temperature drops, which may reduce the sealing ability of the grease lip 35, or cause the dust lip 36 to come into strong contact with the sleeve 42A, applying a large torque to the inner ring 6. Therefore, it is desirable that no gap is generated between the inner circumferential portion of the elastic flange 45 and the outer circumferential surface of the inner ring 6, even under high loads on the wheel bearing 1, thereby maintaining the sealing of the internal space.

[0045] To ensure the sealing of the internal space, the inner diameter of the cylindrical portion 52 of the protrusion 50 in the initial state is smaller than the inner diameter of the sleeve 42A. Preferably, the inner radius R1 of the sleeve 42A in the initial state (refer to...) Figure 5 The difference between the inner radius R2 of the cylindrical portion 52 of the protrusion 50 and the inner radius R2 of the protrusion 50 is, for example, 0.1 mm. Therefore, the interference In2 of the cylindrical portion 52 of the protrusion 50 relative to the inner ring 6 can be set to be 0.1 mm larger than the interference In1 of the sleeve 42A relative to the inner ring 6.

[0046] In the initial state, the length x of the cylindrical portion 52 on the inner circumferential surface of the protrusion 50 is preferably 0.15 mm or more. In this case, even if the pressure in the internal space sealed by the sealing device 21 increases, a gap is unlikely to form between the protrusion 50 of the elastic flange portion 45 and the cylindrical outer circumferential surface of the inner ring 6. Therefore, the sealing performance of the internal space sealed by the sealing device 21 is maintained.

[0047] In the initial state, the length x of the cylindrical portion 52 is preferably less than half of the distance D from the end face 45a (the surface exposed on the atmospheric side) of the elastic flange portion 45 to the end 52a on the sleeve 42A side of the cylindrical portion 52. In this case, because the contact pressure of the protrusion 50 relative to the outer peripheral surface of the inner ring 6 is high, even if the pressure of the internal space sealed by the sealing device 21 increases, a portion of the protrusion 50 will not protrude further towards the atmospheric side than the end face 45a of the elastic flange portion 45, thus preventing large deformation of the protrusion 50, and therefore no gap will be generated between the protrusion 50 and the outer peripheral surface of the inner ring 6.

[0048] Figure 5 This is a partially enlarged sectional view of the sealing device of a comparative example. Figure 4 In, with Figure 5 Similarly, the elastic flange 45 (particularly the protrusion 50) that deforms upon contact with the inner ring 6 is shown in solid lines, while the protrusion 50 in its initial state is shown in dashed lines. ​In the comparative example, the length x of the cylindrical portion 52 in the initial state is greater than half the distance D from the end face 45a of the elastic flange portion 45 to the end 52a of the cylindrical portion 52. In this case, the contact pressure of the protrusion 50 relative to the outer peripheral surface of the inner ring 6 is low, so when the pressure in the internal space enclosed by the sealing device 21 increases, a portion of the protrusion 50 may protrude more towards the atmosphere than the end face 45a of the elastic flange portion 45. When the protrusion 50 deforms so greatly, a gap is created between the protrusion 50 and the outer peripheral surface of the inner ring 6, and leakage L of air or lubricant may occur through the gap between the protrusion 50 and the outer peripheral surface of the inner ring 6.

[0049] In this embodiment, the distance D is 0.65 mm. The distance y between the end face 45a of the radially elastic flange portion 45 of the second sealing member 40 and the inclined surface portion 54 intersecting with the cylindrical portion 52 is 0.7 mm. In this case, in the initial state, the angle θ of the truncated conical inclined surface portion 54 relative to the end face 45a is preferably 27 degrees or more and 35 degrees or less.

[0050] If θ is 27 degrees, then the length x of the cylindrical portion 52 in the initial state is 0.3 mm, which is less than half the distance D. Therefore, a portion of the protrusion 50 will not protrude further toward the atmosphere than the end face 45a of the elastic flange portion 45.

[0051] If θ is 35 degrees, then the length x of the cylindrical portion 52 in the initial state is 0.16 mm, which is larger than 0.15 mm. Therefore, even if the pressure in the internal space sealed by the sealing device 21 increases, a gap is not easily generated between the protrusion 50 of the elastic flange portion 45 and the cylindrical outer peripheral surface of the inner ring 6.

[0052] The present invention has been illustrated above with reference to preferred embodiments, but it is to be understood that changes in form and detail can be made by those skilled in the art without departing from the scope of the invention as set forth in the claims. Such changes, alterations, and modifications should be included within the scope of the present invention.

[0053] For example, in the above embodiment, the inner component, i.e., the hub 4 and the inner ring 6, are rotating components, while the outer component, i.e., the outer ring 8, is a stationary component. However, the present invention is not limited to the above embodiment and can be applied to sealing multiple components that rotate relative to each other. For example, the inner component may be stationary while the outer component rotates, or all of these components may rotate.

[0054] The application of this invention is not limited to sealing wheel hub bearings 1. For example, the sealing device or sealing structure of this invention can also be used in differential gear mechanisms or other power transmission mechanisms of motor vehicles, bearings or other support mechanisms of drive shafts of motor vehicles, bearings or other support mechanisms of rotating shafts of pumps, etc.

[0055] In the above embodiment, the front ends of the side lips 37 and 38 of the first sealing member 30 contact the rigid flange portion 42B of the second sealing member 40. However, the side lips 37 and 38 may not contact the rigid flange portion 42B. The number of side lips is not limited to the embodiment. Instead of side lips or in addition to side lips, protrusions that facilitate the discharge of foreign matter may be provided in the first sealing member 30 or the second sealing member 40.

[0056] Explanation of reference numerals in the attached figures

[0057] 1. Wheel hub bearing

[0058] 6. Inner ring (inner component)

[0059] 8. Outer ring (outer component)

[0060] 21 Sealing device

[0061] 30 First sealing component

[0062] 33 Cylindrical section

[0063] 34. Circular portion

[0064] 35, 36 Radial lips

[0065] 40 Second sealing component

[0066] 41 Elastic Ring

[0067] 42 Rigid Ring

[0068] 42A Sleeve

[0069] 42B Rigid flange

[0070] 44 Flange

[0071] 45. Elastic flange portion

[0072] 45a end face

[0073] 50 protrusions

[0074] 52 Cylindrical section

[0075] 52a end

[0076] 53 Inclined surface section

[0077] 54 Inclined surface section

Claims

1. A sealing device disposed between an inner member and an outer member that rotate relative to each other, and sealing the gap between the inner member and the outer member, the sealing device being characterized in that it comprises: The first sealing member has a cylindrical portion mounted on the outer member, an annular portion extending radially inward from the cylindrical portion, and a lip extending from the annular portion; and The second sealing member has a cylindrical sleeve into which the inner member is inserted, and a flange extending radially outward from the sleeve, the flange being opposite to the annular portion of the first sealing member, and the lip of the first sealing member being slidably in contact with the sleeve. The sleeve of the second sealing member is formed of a rigid material. The flange of the second sealing member has: a rigid flange portion made of rigid material connected to the sleeve; and an annular elastic flange portion made of elastic material that is in close contact with the rigid flange portion. An annular protrusion is integrally formed on the inner circumference of the elastic flange portion, which contacts the cylindrical outer circumferential surface of the inner member. In the initial state where the elastic flange does not contact the outer peripheral surface of the inner member and does not deform, the inner peripheral surface of the protrusion has a cylindrical portion and two truncated conical inclined surface portions adjacent to the cylindrical portion. When the elastic flange portion is deformed due to contact with the outer peripheral surface of the inner member, the cylindrical portion and the two truncated conical inclined surface portions are also deformed due to contact with the outer peripheral surface of the inner member. In the initial state, the inner diameter of the cylindrical portion is smaller than the inner diameter of the sleeve. In the initial state, the length of the cylindrical portion of the protrusion along the axial direction of the sealing device is 0.15 mm or more.

2. The sealing device according to claim 1, characterized in that, In the initial state, the length of the cylindrical portion of the protrusion along the axial direction of the sealing device is less than half the distance from the end face of the elastic flange portion opposite to the rigid flange portion along the axial direction of the sealing device to the sleeve-side end of the cylindrical portion along the axial direction of the sealing device.

3. The sealing device according to claim 1 or 2, characterized in that, In the initial state, the angle of the truncated conical inclined surface portion between the cylindrical portion of the protrusion and the end face of the elastic flange portion opposite to the rigid flange portion is less than 35 degrees relative to the end face.

4. The sealing device according to claim 1 or 2, characterized in that, In the initial state, the angle of the truncated conical inclined surface portion between the cylindrical portion of the protrusion and the end face of the elastic flange portion opposite to the rigid flange portion is 27 degrees or more relative to the end face.

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