Wheel bearing device

Abstract

In a wheel bearing device, even when the space for the sealing device is relatively small, it is possible to improve the design flexibility of the sealing device while preventing a decrease in the strength of the opposing surfaces of the inner members, thereby making it easier to design a sealing device that achieves both a reduction in rotational torque and prevention of the ingress of foreign matter such as muddy water. [Solution] A wheel bearing device 1, wherein the sealing device comprises a core metal 20 fitted to an outer member, and an elastic member 30 joined to the core metal 20 and having a sealing lip extending toward an inner member, the inner member having an opposing surface 3e including a region facing the sealing device, the opposing surface 3e including an arcuate surface 3g with a radius of curvature R of 1.5 mm to 4.0 mm, and a heat-cured hardened surface 3i having a surface hardness of 55 HRC or more.

Description

Technical Field

[0001] The present invention relates to a wheel bearing device.

Background Art

[0002] In recent years, in vehicles using wheel bearing devices, fuel regulations have been imposed due to social backgrounds such as energy conservation and decarbonization, and the trend toward electrification has been advancing. In the future, in electric vehicles that use in-vehicle batteries as the main power source and are expected to increase in popularity, the vehicle weight is larger and the axle load tends to increase compared to gasoline vehicles.

[0003] Generally, when the axle load increases, the rotational torque of the wheel bearing device increases, and it is necessary to increase the size of the wheel bearing device from the viewpoint of strength. For example, in a wheel bearing device used in an electric vehicle, the axial distance from the outer side surface of the wheel mounting flange of the hub ring to the inner side end of the inner ring is smaller than the outer diameter of the inner side end of the outer ring, and it tends to be narrow and large in diameter. In addition, the mounting dimensions of the wheel bearing device often do not change significantly from the conventional ones, and in order to achieve a narrow and large diameter, it is conceivable to cope with this by reducing the dimensions of each part.

[0004] Patent Document 1 describes a sealed rolling bearing including an outer member having an outer rolling surface formed on its inner circumference, an inner member having an inner rolling surface formed on its outer circumference facing the outer rolling surface, rolling elements rotatably accommodated between these two rolling surfaces, and a seal device (sealing device) mounted in an annular space formed between the outer member and the hub ring, in which the seal device has a seal lip made of an elastic member. Further, in the bearing described in Patent Document 1, the space where the seal device is arranged is configured to be relatively small, and the seal lip of the seal device protrudes outside the outer member and has a role of blocking muddy water and the like flowing in along the outer member. By configuring it in this way, even when the space where the seal device is arranged is configured to be relatively small, it can be seen that the seal device is arranged to correspond to this to prevent the intrusion of foreign matters such as muddy water.

Prior Art Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2013-190101 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] Here, reducing the space in which the sealing device is installed may decrease the design flexibility of the sealing device. This reduced design flexibility can make it difficult to design a sealing device that simultaneously reduces rotational torque and prevents the ingress of foreign matter such as muddy water. In addition, in order to secure space for the sealing device, it may be possible to reduce the size of the opposing surface of the inner member, including the area facing the sealing device. However, reducing the size of the opposing surface of the inner member in this way may reduce the strength of the opposing surface of the inner member.

[0007] Therefore, the present invention aims to provide a wheel bearing device that, even when the space in which the sealing device is arranged is relatively small, improves the design freedom of the sealing device while preventing a decrease in the strength of the opposing surfaces of the inner members, thereby facilitating the design of a sealing device that achieves both a reduction in rotational torque and prevention of the intrusion of foreign matter such as muddy water. [Means for solving the problem]

[0008] That is, an outer member having double rows of outer raceway surfaces on its inner circumference, An inner member having double rows of inner raceway surfaces opposite to the double rows of outer raceway surfaces, A double row of rolling elements is rotatably housed between the raceway surfaces of the outer member and the inner member, A sealing device fitted to the outer member and closing the open end of the annular space formed by the outer member and the inner member, A wheel bearing device comprising, The sealing device comprises a core metal that fits into the outer member, and an elastic member joined to the core metal and having a sealing lip that extends toward the inner member. The inner member has a facing surface that includes a region facing the sealing device, The opposing surface includes an arcuate surface with a radius of curvature R of 1.5 mm to 4.0 mm, and is a heat-cured hardened surface with a surface hardness of 55 HRC or higher. [Effects of the Invention]

[0009] The present invention provides the following effects. Specifically, even when the space in which the sealing device is installed is relatively small, it is possible to improve the design freedom of the sealing device while preventing a decrease in the strength of the opposing surfaces of the internal members, thereby making it easier to design a sealing device that achieves both a reduction in rotational torque and prevention of the ingress of foreign matter such as muddy water. [Brief explanation of the drawing]

[0010] [Figure 1] A cross-sectional view showing a wheel bearing device according to one embodiment of the present invention. [Figure 2] This is an enlarged cross-sectional view showing the hub wheel of a wheel bearing device. [Figure 3] Similarly, this is an enlarged cross-sectional view showing the outer side opening, which is an annular space between the outer ring and the hub ring of a wheel bearing device, and the outer side sealing member that fits into it. [Figure 4] This is an enlarged cross-sectional view showing the core metal of the outer seal member of a wheel bearing device. [Modes for carrying out the invention]

[0011] The embodiments for carrying out the present invention will be described below with reference to the attached drawings.

[0012] [Overall configuration of a wheel bearing system] First, the wheel bearing device 1 shown in Figures 1 to 4 will be described. The wheel bearing device 1 shown in Figure 1 is one embodiment of the wheel bearing device according to the present invention, and supports a wheel so as to be rotatable in the suspension system of a vehicle such as an automobile.

[0013] As shown in Figure 1, the wheel bearing device 1 has a configuration referred to as the third generation, and comprises an outer ring 2 which is an outer member, a hub ring 3 and an inner ring 4 which are inner members, two rows of inner ball rows 5 and outer ball rows 6 which are rolling rows, an inner sealing member 9 and an outer sealing member 10.

[0014] Here, "inner side" refers to the side of the wheel bearing device 1 that is attached to the vehicle body, and "outer side" refers to the side of the wheel bearing device 1 that is attached to the vehicle body. Furthermore, "axial direction" refers to the direction along the rotation axis X of the wheel bearing device 1, with one axial side being the outer side and the other axial side being the inner side. Furthermore, the direction perpendicular to the rotation axis of the wheel bearing device 1 is referred to as the radial direction. In the following, "cross-section" will be described as a cross-section that passes through the rotation axis of the wheel bearing device 1 and is parallel to the rotation axis of the wheel bearing device 1.

[0015] The inner circumferential surface of the outer ring 2 has an inner outer raceway groove 2c and an outer outer raceway groove 2d formed thereon.

[0016] On the inner end of the outer circumferential surface of the hub wheel 3, a small-diameter stepped portion 3a is formed, which is smaller in diameter than the outer end and extends axially outward. A wheel mounting flange 3b for attaching a wheel is integrally formed on the outer end of the hub wheel 3. Multiple bolt holes 3d are formed in the wheel mounting flange 3b. Hub bolts for fastening the hub wheel 3 to a wheel or brake component are press-fitted into the bolt holes 3d.

[0017] On the outer peripheral surface of the hub ring 3, an inner track groove 3c on the outer side is provided so as to face the outer track groove 2d on the outer side of the outer ring 2. That is, on the outer side of the inner member, the inner track groove 3c is formed by the hub ring 3. On the outer side of the inner track groove 3c, a facing surface 3e including a region facing the outer seal member 10 is formed. An outer side opening 2b, which is an annular space, is formed between the outer ring 2 and the hub ring 3. The outer seal member 10 is fitted into the outer side opening 2b to prevent the intrusion of foreign matters such as muddy water from the outer side opening 2b. The outer seal member 10 is an example of a sealing device.

[0018] The inner ring 4 is provided on the small-diameter step portion 3a of the hub ring 3. The inner ring 4 is press-fitted into the small-diameter step portion 3a via a predetermined caulking washer. Further, the hub ring 3 and the inner ring 4 are integrated by a caulked portion obtained by plastically deforming and caulking the inner end portion of the small-diameter step portion 3a in the hub ring 3, preventing the inner ring 4 from coming off axially with respect to the hub ring 3. The inner ring 4 applies preload to the inner ball row 5 and the outer ball row 6, which are rolling rows. On the outer peripheral surface of the inner ring 4, an inner track groove 4a on the inner side is provided so as to face the outer track groove 2c on the inner side of the outer ring 2. That is, on the inner side of the inner member, the inner track groove 4a is formed by the inner ring 4. An inner side opening 2a, which is an annular space, is formed between the outer ring 2 and the inner ring 4. The inner seal member 9 is fitted into the inner side opening 2a to prevent the intrusion of foreign matters such as muddy water from the inner side opening 2a. The inner seal member 9 is an example of a sealing device.

[0019] The inner ball row 5 and the outer ball row 6, which are rolling rows, are constituted by a plurality of balls 7, which are rolling elements, being held by a cage 8. The inner ball row 5 is sandwiched between the inner raceway groove 4a of the inner ring 4 and the outer raceway groove 2c on the inner side of the outer ring 2 so as to be freely rotatable. The outer ball row 6 is sandwiched between the inner raceway groove 3c of the hub ring 3 and the outer raceway groove 2d on the outer side of the outer ring 2 so as to be freely rotatable. That is, the inner ball row 5 and the outer ball row 6 are freely rotatably accommodated between the raceway grooves of both the outer member and the inner member. In the wheel bearing device 1, a double row angular ball bearing is constituted by the outer ring 2, the hub ring 3 and the inner ring 4, the inner ball row 5, and the outer ball row 6.

[0020] [Structure of Opposing Surface of Hub Ring] As shown in FIGS. 1 to 3, an opposing surface 3e including a region opposing the outer seal member 10 is formed at the base of the wheel mounting flange 3b of the hub ring 3. The opposing surface 3e is configured in an annular shape in the circumferential direction with respect to the rotation axis X and is connected to the inner raceway groove 3c. The opposing surface 3e and the inner raceway groove 3c are hardened treatment surfaces 3i subjected to thermosetting treatment. The surface hardness of the opposing surface 3e is configured to be 55 HRC or more. The opposing surface 3e includes a sliding contact portion with which the seal lip of the outer seal member 10 makes sliding contact and an arcuate surface 3g with which the seal lip of the outer seal member 10 does not make sliding contact. The sliding contact portion of the opposing surface 3e has an axial surface 3f and a radial surface 3h.

[0021] The axial surface 3f of the opposing surface 3e of the hub wheel 3 is composed of a straight surface (axial straight surface) parallel to the axial direction in a cross section passing through and parallel to the axis of rotation X. The axial surface 3f is located on the inner side of the arcuate surface 3g and on the outer side of the inner raceway groove 3c. The inner end of the axial surface 3f is connected to the outer end of the inner raceway groove 3c. The arcuate surface 3g is composed of a surface that is convex toward the inner diameter side. The arcuate surface 3g is located between the axial surface 3f and the radial surface 3h. The inner end of the arcuate surface 3g is connected to the outer end of the axial surface 3f. The arcuate surface 3g is composed of a radius of curvature R of 1.5 mm to 4.0 mm. The radial surface 3h is composed of a straight surface (radial straight surface) parallel to the radial direction. The radial surface 3h is located on the outer diameter side of the arcuate surface 3g. The inner end of the radial surface 3h is connected to the outer diameter end of the arcuate surface 3g. The radial surface 3h faces the outer end face 2e of the outer ring 2 in the axial direction.

[0022] As described above, the arcuate surface 3g of the opposing surface 3e of the hub wheel 3 has a radius of curvature R of 1.5 mm to 4.0 mm. Therefore, even when the space for the sealing device is relatively small, the arcuate surface 3g of the opposing surface 3e of the hub wheel 3 can be made relatively small, improving the design freedom of the outer side sealing member 10. Thus, it is possible to design the outer side sealing member 10 to achieve both a reduction in rotational torque and prevention of the intrusion of foreign matter such as mud and water, which can be relatively easily accomplished. Furthermore, as described above, the opposing surface 3e of the hub wheel 3 is a heat-cured hardened surface 3i with a surface hardness of 55 HRC or higher. Therefore, even when the arcuate surface 3g of the opposing surface 3e of the hub wheel 3 is made relatively small as described above, it is possible to prevent a decrease in the strength of the opposing surface 3e of the hub wheel 3.

[0023] [Specific configuration of the outer sealing member] As shown in Figures 3 to 4, the outer sealing member 10 comprises a core metal 20 and an elastic member 30.

[0024] The core metal 20 is configured in a substantially annular shape and is fitted onto the inner circumference of the outer end of the outer ring 2. The core metal 20 is made of a metal member, for example, steel. The core metal 20 is located on the inner side of the arcuate surface 3g of the opposing surface 3e of the hub ring 3. When viewed from the radial direction, the core metal 20 overlaps with the axial surface 3f of the opposing surface 3e of the hub ring 3. The core metal 20 has a fitting portion 21 and a side plate portion 22.

[0025] The fitting portion 21 of the core metal 20 is cylindrical and fits onto the inner circumference of the outer end of the outer ring 2. The fitting portion 21 is configured parallel to the axial direction. The side plate portion 22 is located on the inner diameter side of the fitting portion 21 and extends inward from the fitting portion 21. The outer diameter side end of the side plate portion 22 is connected to the outer end of the fitting portion 21. The side plate portion 22 is configured to bend at multiple points.

[0026] The side plate portion 22 of the core metal 20 has an outer diameter side portion 23 and an inner diameter side portion 24. The outer diameter side portion 23 of the side plate portion 22 is configured in a substantially annular shape and is located on the inner diameter side of the fitting portion 21. The outer diameter end of the outer diameter side portion 23 is connected to the outer end of the fitting portion 21. The outer diameter side portion 23 extends from the fitting portion 21 on the outer and inner sides, further extends from its outer end on the inner side, and further extends from its inner end on the inner side. The inner diameter side portion 24 is configured in an annular shape and is located on the inner diameter side of the outer diameter side portion 23. The outer diameter end of the inner diameter side portion 24 is connected to the inner diameter end of the outer diameter side portion 23. The inner diameter side portion 24 extends from the outer diameter side portion 23 on the inner side. The inner diameter side portion 24 is located in the axial direction, outward from the inner end of the fitting portion 21 and inward from the outer end of the outer diameter side portion 23.

[0027] The elastic member 30 is made of, for example, synthetic rubber and is configured to be elastically deformable. The elastic member 30 is joined to the core metal 20 by vulcanization bonding or the like. The elastic member 30 has a base portion 31 and a seal lip.

[0028] The base 31 of the elastic member 30 is provided so as to cover the outer side surface of the side plate portion 22 of the core metal 20, the inner diameter side end surface of the side plate portion 22, and a part of the inner outer side surface of the side plate portion 22. The base 31 of the elastic member 30 is formed as part of the core metal 20.

[0029] The seal lip of the elastic member 30 extends from the base 31 toward the hub wheel 3 and slides against the axial surface 3f and radial surface 3h of the opposing surface 3e of the hub wheel 3. The seal lip has two axial lips 32 and 33 and a radial lip 34.

[0030] The axial lips 32 and 33 of the elastic member 30 are configured to be elastically deformable. The axial lips 32 and 33 prevent foreign matter such as mud and water from entering between the hub wheel 3 and the core metal 20. The axial lips 32 and 33 extend from the side plate portion 22 of the core metal 20 toward the radial surface 3h of the opposing surface 3e of the hub wheel 3. The axial lips 32 and 33 extend toward the outer side and the outer diameter side and contact the radial surface 3h of the opposing surface 3e of the hub wheel 3. The axial lips 32 and 33 do not contact the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. The axial lips 32 and 33 are arranged side by side in the radial direction. The axial lip 32 is positioned on the outer diameter side than the axial lip 33. The axial lip 33 is positioned radially between the axial lip 32 and the radial lip 34 and is configured as an intermediate lip. Furthermore, the axial lip 32 may be configured to face the opposing surface 3e of the hub wheel 3 with a gap between them, so as not to contact the opposing surface 3e.

[0031] As described above, the opposing surface 3e of the hub wheel 3 has a radial surface 3h (radially straight surface) on the outer diameter side of the arcuate surface 3g, and the two axial lips 32 and 33 of the elastic member 30 in the outer side sealing member 10 contact the radial surface 3h of the opposing surface 3e of the hub wheel 3. Therefore, the rotational torque can be stabilized compared to a configuration in which the axial lips 32 and 33 of the elastic member 30 contact an arcuate surface.

[0032] The arcuate surface 3g of the opposing surface 3e of the hub wheel 3 is not polished. Furthermore, since the two axial lips 32 and 33 of the elastic member 30 come into contact, the radial surface 3h of the opposing surface 3e of the hub wheel 3 is polished to reduce rotational torque. That is, the surface roughness of the portion of the radial surface 3h of the opposing surface 3e of the hub wheel 3 where the two axial lips 32 and 33 of the elastic member 30 come into contact is smaller than the surface roughness of the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. It is also possible to configure the hub wheel 3 so that only the portion of the radial surface 3h of the opposing surface 3e of the hub wheel 3 where the axial lips 32 and 33 of the elastic member 30 come into contact and its surrounding area is polished.

[0033] As described above, the surface roughness of at least the portion of the radial surface 3h (radially straight surface) of the opposing surface 3e of the hub wheel 3 where the two axial lips 32 and 33 of the elastic member 30 of the outer side sealing member 10 come into contact is smaller than the surface roughness of the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. Therefore, the load of polishing on the opposing surface 3e of the hub wheel 3 can be reduced.

[0034] The radial lip 34 of the elastic member 30 is configured to be elastically deformable. The radial lip 34 prevents foreign matter such as mud and water from entering between the hub wheel 3 and the core metal 20, and also prevents grease from leaking out from the outer ball row 6 side. The radial lip 34 extends from the side plate portion 22 of the core metal 20 toward the axial surface 3f of the opposing surface 3e of the hub wheel 3. The radial lip 34 extends toward the inner side and the inner diameter side, and contacts the axial surface 3f of the opposing surface 3e of the hub wheel 3. The radial lip 34 does not contact the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. Note that the seal lip of the elastic member 30 can also be configured without the radial lip 34.

[0035] As described above, the opposing surface 3e of the hub wheel 3 has an axial surface 3f (straight axial surface) on the inner side (other axial side) of the arcuate surface 3g, and the radial lip 34 of the elastic member 30 in the outer side sealing member 10 contacts the axial surface 3f of the opposing surface 3e of the hub wheel 3. Therefore, the rotational torque can be stabilized compared to a configuration in which the radial lip 34 of the elastic member 30 contacts an arcuate surface.

[0036] The arcuate surface 3g of the opposing surface 3e of the hub wheel 3 is not polished. Furthermore, since the radial lip 34 of the elastic member 30 makes contact, the axial surface 3f of the opposing surface 3e of the hub wheel 3 is polished to reduce rotational torque. That is, the surface roughness of the portion of the axial surface 3f of the opposing surface 3e of the hub wheel 3 that contacts the radial lip 34 of the elastic member 30 is smaller than the surface roughness of the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. It is also possible to configure the hub wheel 3 so that only the portion of the axial surface 3f of the opposing surface 3e of the hub wheel 3 that contacts the radial lip 34 of the elastic member 30 and its surrounding area is polished.

[0037] As described above, the surface roughness of at least the portion of the axial surface 3f (axial straight surface) of the opposing surface 3e of the hub wheel 3 that contacts the radial lip 34 of the elastic member 30 of the outer side seal member 10 is smaller than the surface roughness of the arcuate surface 3g of the opposing surface 3e of the hub wheel 3. Therefore, the load of polishing on the opposing surface 3e of the hub wheel 3 can be reduced.

[0038] By configuring the arcuate surface 3g of the opposing surface 3e of the hub wheel 3 to be relatively small as described above, it is possible to satisfy the relationship b / a ≤ 50% between "the length a of the core metal 20 in the axial direction" and "the length b of the core metal 20 from the outer end of the outer diameter side portion 23 of the side plate portion 22 of the core metal 20 (one axial end face of the outer diameter side portion 23) to the outer side of the inner diameter side portion 24 (one axial end face of the inner diameter side portion 24)".

[0039] As described above, the relationship b / a ≤ 50% is satisfied for "the length a of the mandrel 20 in the axial direction" and "the length b of the side plate portion 22 of the mandrel 20 from the outer end of the outer diameter side portion 23 (one axial end face of the outer diameter side portion 23) to the outer side of the inner diameter side portion 24 (one axial end face of the inner diameter side portion 24) in the axial direction". Therefore, compared to a design in which the arcuate surface 3g of the opposing surface 3e of the hub wheel 3 is relatively large, the side plate portion 22 of the mandrel 20 can be constructed without large bends in multiple places. Consequently, the difficulty of processing the mandrel 20 can be reduced, and the size of the mandrel 20 can be made relatively small, thereby reducing material costs.

[0040] When the relationship h < 4.7 mm is satisfied for the radial length h of the core metal 20, it is preferable that the relationship b / a ≤ 20% is satisfied for the axial length a of the core metal 20 and the axial length b of the outer side of the outer diameter side portion 23 of the side plate portion 22 of the core metal 20 to the outer side of the inner diameter side portion 24.

[0041] As described above, when the relationship h < 4.7 mm is satisfied for the radial length h of the mandrel 20, the relationship b / a ≤ 20% is satisfied for the axial length a of the mandrel 20 and the axial length b from the outer end of the outer diameter side portion 23 of the side plate portion 22 of the mandrel 20 to the outer side of the inner diameter side portion 24. Therefore, compared to a hub wheel 3 where the arcuate surface 3g of the opposing surface 3e is relatively large, the side plate portion 22 of the mandrel 20 can be constructed without large bends in multiple places. Consequently, the difficulty of processing the mandrel 20 can be reduced, and the size of the mandrel 20 can be made relatively small, thereby reducing material costs.

[0042] When the relationship h > 4.7 mm is satisfied for the radial length h of the core metal 20, it is preferable that the relationship b / a ≤ 30% is satisfied for the axial length a of the core metal 20 and the axial length b of the outer end of the outer diameter side portion 23 of the side plate portion 22 of the core metal 20 to the outer side of the inner diameter side portion 24.

[0043] As described above, when the relationship h > 4.7 mm is satisfied for the radial length h of the mandrel 20, the relationship b / a ≤ 30% is satisfied for the axial length a of the mandrel 20 and the axial length b from the outer end of the outer diameter side portion 23 of the side plate portion 22 of the mandrel 20 to the outer side of the inner diameter side portion 24. Therefore, compared to a hub wheel 3 where the arcuate surface 3g of the opposing surface 3e is relatively large, the side plate portion 22 of the mandrel 20 can be constructed without large bending at multiple points. Consequently, the difficulty of processing the mandrel 20 can be reduced, and the size of the mandrel 20 can be made relatively small, thereby reducing material costs.

[0044] Although a wheel bearing device referred to as the third generation has been given as an example, the wheel bearing device according to the present invention is not limited to such a structure. For example, it may be a first-generation or second-generation structure in which a pair of inner rings are press-fitted into the small-diameter stepped portion of the hub ring, or a fourth-generation structure in which inner raceway grooves are formed on the outer circumferential surfaces of the hub ring and the constant velocity universal joint, respectively, and these are used as inner members. Furthermore, although a double-row angular contact ball bearing with balls as the rolling elements has been given as an example, it is not limited to this, and a double-row tapered roller bearing with tapered rollers as the rolling elements is also acceptable.In addition, although the sealing device according to the present invention has been described as an outer-side sealing member 10, it may also be used as an inner-side sealing member 9.

[0045] Although embodiments of the present invention have been described above, the present invention is not limited in any way to these embodiments, but is merely illustrative. It can be implemented in various other forms without departing from the spirit of the invention, and the scope of the present invention is indicated by the claims, and further includes all modifications within the meaning and scope of equivalents as described in the claims. [Explanation of Symbols]

[0046] 1. Wheel bearing device 2 Outer ring 2a Inner side opening 2b Outer side opening 2c Outer raceway groove 2d outer raceway groove 2e Body mounting flange 2f Bolt holes 2g outer end face 3 Hub wheels 3a Small diameter stepped section 3b Wheel mounting flange 3c Inner raceway groove 3e Opposing surface 3f Axial plane 3g arc surface 3h Radial surface 3i Hardened surface 4. Inner Ring 4a Inner raceway groove on the inner side 5. Inner ball row 6 Outer ball row 7 Ball 8 Cage 9. Inner side sealing member 10 Outer side sealing member 20 Mandrel 21 Fitting part 22 Side plate part 23 Outer diameter side 24 Inner diameter side 30 Elastic members 31 Base 32 Axial Lip 33 Axial Lip 34 Radial Lip

Claims

1. An outer member having double rows of outer raceway surfaces on its inner circumference, An inner member having double rows of inner raceway surfaces opposite to the double rows of outer raceway surfaces, A double row of rolling elements is rotatably housed between the raceway surfaces of the outer member and the inner member, A sealing device fitted to the outer member and closing the open end of the annular space formed by the outer member and the inner member, A wheel bearing device comprising, The sealing device comprises a core metal that fits into the outer member, and an elastic member joined to the core metal and having a sealing lip that extends toward the inner member. The inner member has a facing surface that includes a region facing the sealing device, The aforementioned opposing surfaces include an arcuate surface with a radius of curvature R of 1.5 mm to 4.0 mm, and are hardened surfaces subjected to heat-setting treatment with a surface hardness of 55 HRC or higher, in a wheel bearing device.

2. The opposing surface includes a sliding contact portion into which the seal lip slides, The sliding contact portion has a radially straight surface on the outer diameter side of the arcuate surface, The seal lip has two axial lips, The wheel bearing device according to claim 1, wherein the two axial lips contact the radially straight surface.

3. The wheel bearing device according to claim 2, wherein the surface roughness of the portion of the radial straight surface in which at least two of the axial lips contact is smaller than the surface roughness of the arcuate surface.

4. The opposing surface includes a sliding contact portion into which the seal lip slides, The sliding contact portion has an axially straight surface on the other axial end of the arcuate surface, The seal lip has a radial lip, The wheel bearing device according to claim 1, wherein the radial lip contacts the axially straight surface.

5. The wheel bearing device according to claim 4, wherein the surface roughness of at least the portion of the axial straight surface that contacts the radial lip is smaller than the surface roughness of the arcuate surface.

6. The core metal has a fitting portion that fits into the outer member and a side plate portion that extends inward from the fitting portion. The side plate portion has an outer diameter side portion located on the inner diameter side of the fitting portion, and an inner diameter side portion located on the inner diameter side of the outer diameter side portion. The inner diameter side portion is located axially on one side of the other axial end of the fitting portion, and axially on the other side of the outer diameter side portion, Regarding "the length h of the core metal in the radial direction," if the relationship h < 4.7 mm is satisfied, A wheel bearing device according to any one of claims 1 to 5, wherein the relationship b / a ≤ 20% is satisfied with respect to "the length a of the core metal in the axial direction" and "the length b of the length from one axial end face of the outer diameter side of the side plate portion of the core metal in the axial direction to one axial end face of the inner diameter side."

7. The core metal has a fitting portion that fits into the outer member and a side plate portion that extends inward from the fitting portion. The side plate portion has an outer diameter side portion located on the inner diameter side of the fitting portion, and an inner diameter side portion located on the inner diameter side of the outer diameter side portion. The inner diameter side portion is located axially on one side of the other axial end of the fitting portion, and axially on the other side of the outer diameter side portion, Regarding "the length h of the core metal in the radial direction," if the relationship h > 4.7 mm is satisfied, A wheel bearing device according to any one of claims 1 to 5, wherein the relationship b / a ≤ 30% is satisfied with respect to "the length a of the core metal in the axial direction" and "the length b of the length from one axial end face of the outer diameter side of the side plate portion of the core metal in the axial direction to one axial end face of the inner diameter side."

Images