Bearing device for wheel

Abstract

Provided is a wheel bearing device capable of preventing an increase in rotational torque. A wheel bearing device (1) is provided with: an outer ring (2) having outer raceway surfaces (2c, 2d) on the inner periphery thereof; an inner member comprising a hub ring (3) having a wheel attachment flange (3b) and an inner ring (4) connected to the hub ring, the inner member having inner raceway surfaces (3c, 4a) formed on the hub ring and the inner ring; ball rows (5, 6) accommodated between the outer ring and both raceway surfaces of the inner member; and an outer-side sealing member (10) that closes the outer-side open end of an annular space (15) formed by the outer ring and the inner member, the outer-side sealing member is provided with a core bar (11) and a sealing member (12), and the hub ring has a sealing region portion (3d) that is located at the base of the wheel attachment flange and that is in contact with the sealing member. The arithmetic average roughness (Ra) of the sealing region portion is 0.2 [mu] m or less and 0.01 [mu] m or more.

Description

Technical Field

[0001] The utility model relates to a bearing device for a wheel. Background Art

[0002] In the past, a wheel bearing device for supporting a wheel to rotate freely in a suspension device of a motor vehicle, etc. is known. The wheel bearing device is provided with a sealing device that blocks the open end of the annular space formed by the outer member and the inner member to prevent the entry of foreign matter such as mud and water.

[0003] For example, the sealing device disclosed in Patent Document 1 is composed of a core metal fitted with the inner peripheral surface of an outer member, and a sealing member joined to the core metal and having sealing lips such as a grease lip and an intermediate lip that contact the inner member. In such a sealing device, there is a space surrounded by the sealing lip and the surface of the inner member with which the sealing lip contacts.

[0004] Prior Art Literature

[0005] Patent Literature

[0006] Patent Document 1: International Publication No. 2020 / 012953 Utility Model Content

[0007] Issues to be solved by utility models

[0008] In the sealing device disclosed in the above-mentioned Patent Document 1, if the pressure in the space surrounded by the sealing lip and the inner member rises as the temperature of the rotating wheel bearing device rises, and the surface roughness of the contact surface of the sealing lip in the inner member is large, a gap is easily formed between the sealing lip and the contact surface in the inner member, and there is a possibility that the air in the space escapes from the gap.

[0009] When air escapes from the space and the temperature of the stopped wheel bearing device decreases, the pressure in the space decreases and the sealing lip is adsorbed to the contact surface of the inner member, which becomes a major factor in increasing the rotational torque of the wheel bearing device.

[0010] Therefore, the present invention provides a wheel bearing device that can suppress a pressure drop in a space surrounded by a contact surface between a seal lip and an inner member, thereby preventing an increase in rotational torque.

[0011] Solutions to Solve Problems

[0012] That is, a wheel bearing device comprises: an outer member having a double-row outer raceway surface on the inner circumference; an inner member consisting of a hub ring having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub ring, and an inner raceway surface opposite to the outer raceway surface is formed on the hub ring and the raceway surface forming member; double-row rolling elements, which are freely accommodated between the two raceway surfaces of the outer member and the inner member; and a sealing device, which seals the open end of one axial end side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises: a core metal, which is embedded in one axial end portion of the outer member; and a sealing member, which is joined to the core metal, the hub ring has a sealing area portion located at the base of the wheel mounting flange and for the sealing member to contact, and the arithmetic mean roughness Ra of the sealing area portion is less than 0.2μm and greater than 0.01μm.

[0013] In addition, a wheel bearing device comprises: an outer member having a double-row outer raceway surface on the inner circumference; an inner member consisting of a hub ring having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub ring, and an inner raceway surface opposite to the outer raceway surface is formed on the hub ring and the raceway surface forming member; double-row rolling elements, which are freely accommodated between the two raceway surfaces of the outer member and the inner member; and a sealing device, which seals the open end of one axial end side of the annular space formed by the outer member and the inner member, wherein the sealing device comprises: a core metal, which is embedded in one axial end portion of the outer member; and a sealing member, which is joined to the core metal, the hub ring has a sealing area portion located at the base of the wheel mounting flange and contacted by the sealing member, and the maximum height roughness Rz of the sealing area portion is less than 2.5 μm and greater than 0.1 μm.

[0014] In addition, the wheel bearing device comprises: an outer member having a double-row outer raceway surface on the inner circumference; an inner member consisting of a hub ring having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub ring, wherein an inner raceway surface opposite to the outer raceway surface is formed on the hub ring and the raceway surface forming member; double-row rolling elements which are freely accommodated between the two raceway surfaces of the outer member and the inner member; and a sealing device which seals the outer member and the inner member. The sealing device comprises: a core bone which is embedded in one axial end of the outer square member; and a sealing member which is joined to the core bone. The hub ring has a sealing area portion which is located at the base of the wheel mounting flange and is contacted by the sealing member. The arithmetic mean roughness Ra of the sealing area portion is less than 0.2 μm and greater than 0.01 μm, and the maximum height roughness Rz of the sealing area portion is less than 2.5 μm and greater than 0.1 μm.

[0015] Utility Model Effect

[0016] According to the present invention, it is possible to prevent the rotation torque of the wheel bearing device from increasing. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a side cross-sectional view showing a wheel bearing device.

[0018] Figure 2 It is a side cross-sectional view showing an outer side sealing member and a sealing region of the hub wheel with which the outer side sealing member contacts.

[0019] Figure 3 This is a diagram showing the relationship between the rotation speed ratio and the rotation torque ratio in the wheel bearing device.

[0020] Figure 4 It is a partial side cross-sectional view showing a wheel bearing device according to a second embodiment.

[0021] Description of reference numerals:

[0022] 1 Wheel bearing device

[0023] 2 Outer ring

[0024] 2a Inner opening

[0025] 2b Outer side opening

[0026] 2c (Inner side) Outer track surface

[0027] 2d (outer side) outer track surface

[0028] 3 Wheel hub

[0029] 3a Small path step

[0030] 3b Wheel mounting flange

[0031] 3c (Outer side) Inner track surface

[0032] 3d sealed area

[0033] 3d1 Part 1

[0034] 3d2 Part 2

[0035] 4 Inner ring

[0036] 4a (Inner side) Inner track surface

[0037] 5 Inner side ball row

[0038] 6 Outer side ball row

[0039] 7 Ball

[0040] 8 Retainer

[0041] 10 Outer side sealing member

[0042] 11 Core bone

[0043] 12 Sealing member

[0044] 12a Grease lip

[0045] 12b First lip

[0046] 12c Second side lip

[0047] 15 Ring Space

[0048] 20 Constant velocity joint

[0049] 28 Inner track groove

[0050] R Radius of curvature. DETAILED DESCRIPTION

[0051] Hereinafter, embodiments for carrying out the present invention will be described using the drawings.

[0052] [Wheel bearing device]

[0053] Figure 1 The wheel bearing device 1 shown is one embodiment of the wheel bearing device of the present invention, and is used to rotatably support a wheel in a suspension device of a vehicle such as an automobile.

[0054] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1. In addition, the outer side refers to the wheel side of the wheel bearing device 1 when installed on the vehicle body as one side of the axial direction, and the inner side refers to the vehicle body side of the wheel bearing device 1 when installed on the vehicle body as the other side of the axial direction.

[0055] The wheel bearing device 1 has a structure called the third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, a double inner ball row 5 and an outer ball row 6 as rolling rows, an inner side sealing member 9, and an outer side sealing member 10. The inner ring 4 is an example of a raceway surface forming member connected to the hub ring.

[0056] An inner opening 2a into which the inner sealing member 9 can be fitted is formed at the inner end of the outer ring 2. An outer opening 2b into which the outer sealing member 10 can be fitted is formed at the outer end of the outer ring 2.

[0057] The inner sealing member 9 is fitted into the inner opening 2a, thereby sealing the inner opening end of the annular space 15 formed by the outer ring 2 and the inner member. The outer sealing member 10 is fitted into the outer opening 2b, thereby sealing the outer opening end of the annular space 15.

[0058] The inner side sealing member 9 and the outer side sealing member 10 are sealing devices that seal the open end of the annular space 15 formed by the outer ring 2 as the outer member and the inner member. In this way, the inner side sealing member 9 and the outer side sealing member 10 seal the inner and outer side opening ends of the annular space 15, thereby playing a sealing function of inhibiting foreign matter such as muddy water from intruding into the wheel bearing device 1.

[0059] The inner peripheral surface 2p of the outer ring 2 is formed with an inner outer track surface 2c and an outer outer track surface 2d. The outer peripheral surface 2o of the outer ring 2 is integrally formed with a vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body side member (steering knuckle). The vehicle body mounting flange 2e is provided with bolt holes 2f for inserting the fastening member for fastening the vehicle body side member and the outer ring 2.

[0060] A small-diameter step portion 3a having a smaller diameter than the outer end is formed at the inner end of the outer peripheral surface 3o of the hub ring 3. A wheel mounting flange 3b for mounting a wheel is integrally formed at the outer end of the hub ring 3. Bolt holes 3f are provided in the wheel mounting flange 3b for press-fitting hub bolts 3i.

[0061] The outer peripheral surface 3o of the hub 3 is provided with an outer inner raceway surface 3c facing the outer outer raceway surface 2d of the outer ring 2. In addition, the hub 3 has a sealing area 3d formed at the base of the wheel mounting flange 3b with which the outer seal member 10 contacts.

[0062] The inner ring 4 is provided on the small-diameter step portion 3a of the hub ring 3. An inner raceway surface 4a is provided on the outer peripheral surface 40 of the inner ring 4 so as to face the inner outer raceway surface 2c of the outer ring 2.

[0063] The inner ball row 5 and the outer ball row 6 as rolling rows are formed by retaining a plurality of balls 7 as rolling elements by a retainer 8. The inner ball row 5 is sandwiched between the inner raceway surface 4a of the inner ring 4 and the inner outer raceway surface 2c of the outer ring 2 in a freely rolling manner. The outer ball row 6 is sandwiched between the inner raceway surface 3c of the hub ring 3 and the outer outer raceway surface 2d on the outer side of the outer ring 2 in a freely rolling manner.

[0064] In the wheel bearing device 1 , a double-row tapered roller bearing is formed by the outer ring 2 , the hub ring 3 , the inner ring 4 , the inner ball row 5 , and the outer ball row 6 .

[0065] [Outer side sealing member]

[0066] like Figure 2 As shown, the outer sealing member 10 includes a core metal 11 fitted into the inner periphery of the outer end portion of the outer ring 2 , and a sealing member 12 integrally joined to the core metal 11 .

[0067] The core metal 11 is made of, for example, a steel plate, and includes a cylindrical fitting portion 111 fitted to the inner periphery of the outer opening 2 b of the outer ring 2 , and an inner portion 112 extending from the outer end of the fitting portion 111 toward the inner diameter side.

[0068] The sealing member 12 is formed of an elastic member such as synthetic rubber, and is bonded to the core metal 11 by vulcanization bonding. The sealing member 12 has a grease lip 12a, a first side lip 12b, and a second side lip 12c.

[0069] The grease lip 12 a extends from the inner portion 112 of the core metal 11 toward the inner diameter side and the inner side, and contacts the sealing area portion 3 d .

[0070] The first side lip 12b extends from the inner side portion 112 of the core metal 11 toward the outer side and the outer diameter side of the wheel mounting flange 3b on the outer diameter side of the grease lip 12a. The first side lip 12b contacts the sealing area portion 3d. The first side lip 12b is an example of a side lip.

[0071] The second side lip 12c extends from the inner side portion 112 of the core metal 11 toward the outer side and the outer side of the wheel mounting flange 3b on the outer diameter side than the first side lip 12b. The second side lip 12c contacts the sealing area 3d. The second side lip 12c is an example of a side lip.

[0072] In the outer side sealing component 10, there is a first space S1 surrounded by the grease lip 12a, the first side lip 12b, and the sealing area portion 3d for the grease lip 12a and the first side lip 12b to contact, and a second space S2 surrounded by the first side lip 12b, the second side lip 12c, and the sealing area portion 3d for the first side lip 12b and the second side lip 12c to contact.

[0073] The seal region 3d of the hub wheel 3 includes a first portion 3d1 with which the grease lip 12a contacts, and a second portion 3d2 with which the first side lip 12b and the second side lip 12c contact.

[0074] [Surface roughness of the sealing area]

[0075] The surface roughness of the sealing region 3d is formed to be a small surface roughness with an arithmetic mean roughness Ra of 0.2 μm or less and 0.01 μm or more. In addition, the surface roughness of the sealing region 3d may be formed to be a small surface roughness with a maximum height roughness Rz of 2.5 μm or less and 0.1 μm or more. In addition, the surface roughness of the sealing region 3d may be formed to be a small surface roughness with an arithmetic mean roughness Ra of 0.2 μm or less and 0.01 μm or more and a maximum height roughness Rz of 2.5 μm or less and 0.1 μm or more.

[0076] The arithmetic mean roughness Ra is a value obtained by extracting a portion of the measured roughness curve with a reference length and summing and averaging the absolute values ​​of the deviations from the mean line of the extracted portion to the measured curve. In addition, the maximum height roughness Rz is a value obtained by extracting a portion of the measured roughness curve with a reference length and summing the maximum peak height Rp and the maximum valley depth Rv of the extracted portion.

[0077] If the wheel bearing device 1 rotates, the temperature of the wheel bearing device 1 rises due to friction between the outer ring 2 and the hub ring 3 and the inner ring 4. If the temperature of the wheel bearing device 1 rises, the pressure in the first space S1 and the pressure in the second space S2 rise.

[0078] In this case, if the surface roughness of the sealing area portion 3d is large, there is a possibility that gaps are generated between the first side lip 12b and the sealing area portion 3d and between the second side lip 12c and the sealing area portion 3d, so that the air in the first space S1 and the air in the second space S2 escape from the generated gaps.

[0079] When air escapes from the first space S1 and the second space S2, if the temperature of the stopped wheel bearing device 1 decreases, the pressure in the first space S1 and the second space S2 decreases, and the first side lip 12b and the second side lip 12c are adsorbed on the sealing area portion 3d, which may become an important factor in increasing the rotational torque of the wheel bearing device 1.

[0080] However, in the wheel bearing device 1, since the surface roughness of the sealing area portion 3d is formed small so that the arithmetic mean roughness Ra is 0.2 μm or less and 0.01 μm or more, a gap is less likely to be formed between the sealing area portion 3d and the first side lip 12b and the second side lip 12c.

[0081] Therefore, the air in the first space S1 and the air in the second space S2 can be suppressed from escaping from between the sealed region 3d and the first and second side lips 12b, 12c, and the first and second side lips 12b, 12c can be prevented from being adsorbed to the sealed region 3d.

[0082] This prevents an increase in the rotational torque of the wheel bearing device 1 and prevents deterioration in fuel efficiency of the vehicle on which the wheel bearing device 1 is mounted.

[0083] It should be noted that, when the sealing region 3d is machined, if the sealing region 3d is machined so that the arithmetic mean roughness Ra is less than 0.01 μm or the maximum height roughness Rz is less than 0.1 μm, the machining time and machining cost will increase significantly. Therefore, in the present embodiment, in order to suppress a significant increase in the machining time and machining cost of the sealing region 3d, the lower limit value of the arithmetic mean roughness Ra of the sealing region 3d is set to 0.01 μm, and the lower limit value of the maximum height roughness Rz is set to 0.1 μm.

[0084] In addition, the smaller the surface roughness of the sealing region 3d, the smoother the surface of the sealing region 3d, and the greater the degree of close contact between the first side lip 12b and the second side lip 12c and the sealing region 3d. However, if the arithmetic mean roughness Ra of the sealing region 3d is less than 0.01 μm or the maximum height roughness Rz is less than 0.1 μm, the degree of close contact between the first side lip 12b and the second side lip 12c and the sealing region 3d becomes too large, and the rotation torque of the wheel bearing device 1 may increase. Therefore, in the present embodiment, the lower limit value of the arithmetic mean roughness Ra of the sealing region 3d is set to 0.01 μm, and the lower limit value of the maximum height roughness Rz is set to 0.1 μm, thereby suppressing the increase in the rotation torque of the wheel bearing device 1.

[0085] exist Figure 3In the figure, there is shown the relationship between the rotational speed ratio and the rotational torque ratio in the wheel bearing device 1 when the surface roughness of the sealing area portion 3d is formed to be smaller with an arithmetic mean roughness Ra of 0.2μm, and the relationship between the rotational speed ratio and the rotational torque ratio in the wheel bearing device 1 when the surface roughness of the sealing area portion 3d is formed to be larger with an arithmetic mean roughness Ra of 0.3μm.

[0086] Figure 3 The rotation speed ratio is a value obtained by dividing the actual rotation speed of the wheel bearing device 1 by a predetermined value, and the rotation torque ratio is a value representing the rotation torque when the arithmetic mean roughness Ra of the sealing area portion 3d is 0.3 μm and the rotation speed ratio is 100 as a reference (100%).

[0087] When the arithmetic mean roughness Ra of the sealing region 3d is 0.3 μm, the rotation torque ratio increases as the rotation speed ratio of the wheel bearing device 1 increases. In the range of the rotation speed ratio of 100 to 500, the rotation torque ratio shows a value in the range of about 100% to 130%.

[0088] On the other hand, when the arithmetic mean roughness Ra of the sealing area portion 3d is 0.2 μm, the degree of increase in the rotational torque ratio with the increase in the rotational speed ratio is generally more stable than when the arithmetic mean roughness Ra is 0.3 μm. In addition, in the range of the rotational speed ratio of 100 to 500, the rotational torque ratio is suppressed to a low value of about 60%.

[0089] Therefore, by forming the surface roughness of the sealing area portion 3 d to be small so that the arithmetic mean roughness Ra is 0.2 μm or less, it is possible to suppress an increase in the rotation torque of the wheel bearing device 1 .

[0090] The arithmetic mean roughness Ra of 0.2 μm corresponds to the maximum height roughness Rz of 2.5 μm, and the arithmetic mean roughness Ra of 0.3 μm corresponds to the maximum height roughness Rz of 3.5.

[0091] Therefore, even when the surface roughness of the sealing region 3d is formed so that the maximum height roughness Rz is 2.5 μm, the rotation torque ratio of the wheel bearing device 1 can be suppressed to be lower than when the surface roughness of the sealing region 3d is formed so that the maximum height roughness Rz is 3.5 μm.

[0092] Moreover, even when the surface roughness of the sealing area portion 3d is formed in a manner such that the arithmetic mean roughness Ra is 0.2μm and the maximum height roughness Rz is 2.5μm, the rotational torque ratio of the wheel bearing device 1 can be suppressed to be lower than that when the surface roughness of the sealing area portion 3d is formed in a manner such that the arithmetic mean roughness Ra is 0.3μm and the maximum height roughness Rz is 3.5μm.

[0093] Thus, when the surface roughness of the sealing area portion 3d is smaller and the maximum height roughness Rz is formed to be less than 2.5μm and more than 0.1μm, and when the surface roughness of the sealing area portion 3d is formed to have an arithmetic mean roughness Ra of less than 0.21μm and more than 0.01μm and a maximum height roughness Rz of less than 2.5μm and more than 0.01μm, the increase in the rotational torque of the wheel bearing device 1 can also be suppressed.

[0094] In the wheel bearing device 1, the pressure in the annular space 15 on the outer side of the ball row 6 axially inner than the grease lip 12a becomes higher than the atmospheric pressure, and the air in the first space S1 is difficult to escape into the annular space 15 from between the grease lip 12a and the sealing area portion 3d.

[0095] Therefore, in the wheel bearing device 1, even if the surface roughness of the first portion 3d1 of the sealing area portion 3d contacted by the grease lip 12a is formed to be larger than the surface roughness of the second portion 3d2 of the sealing area portion 3d contacted by the first side lip 12b and the second side lip 12c, the air in the first space S1 can be prevented from escaping into the annular space 15.

[0096] In this way, when the surface roughness of the first part 3d1 of the sealing area part 3d is formed to be larger than the surface roughness of the second part 3d2, the labor required for reducing the surface roughness of the second part 3d2 can be less than the labor required for reducing the surface roughness of the first part 3d1, and the labor required for surface processing of the sealing area part 3d can be reduced as a whole.

[0097] [Shape of the Sealed Area]

[0098] In the wheel bearing device 1, the sealing area portion 3d at the base of the wheel mounting flange 3b in the hub 3 has a curved surface shape that is an arc shape when viewed from the circumferential direction. The curvature radius R of the curved surface shape when viewed from the circumferential direction is set to a range of 3.0 mm or more and 6.5 mm or less. That is, the sealing area portion 3d has a curved surface shape that has a curvature radius R of 3.0 mm or more and 6.5 mm or less when viewed from the circumferential direction.

[0099] If the curvature radius R of the curved surface shape of the sealing area portion 3d is larger than 6.5 mm, the space between the sealing area portion 3d and the sealing member 12 becomes smaller, and the first side lip 12b and the second side lip 12c of the sealing member 12 are easily adsorbed relative to the sealing area portion 3d, which is not preferred.

[0100] Furthermore, if the curvature radius R of the curved surface shape of the sealing area portion 3 d is less than 3.0 mm, the wall thickness of the hub wheel 3 at the base of the wheel mounting flange 3 b becomes small, and the strength of the hub wheel 3 becomes a concern.

[0101] Therefore, the curvature radius R of the curved surface shape of the sealing area portion 3d is set to a range of 3.0 mm to 6.5 mm, thereby sufficiently ensuring the strength of the hub 3 and suppressing the adsorption of the first side lip 12b and the second side lip 12c relative to the sealing area portion 3d.

[0102] [Second Embodiment of Wheel Bearing Device]

[0103] The wheel bearing device 1 can also be Figure 4 The wheel bearing device 1A is configured as shown in FIG. The wheel bearing device 1A includes a constant velocity joint 20 connected to a hub wheel 3A, and does not include an inner ring 4. The constant velocity joint 20 is an example of a raceway surface forming member connected to a hub wheel.

[0104] The constant velocity joint 20 includes a mouth portion 22 for supporting a shaft to which a driving force is input from a driving source, and a stem portion 23 extending outward from the mouth portion 22. The hub 3A has a through hole 3e extending in the axial direction, and the through hole 3e and the stem portion 23 are spline-fitted.

[0105] An inner track groove 28 is formed on the outer peripheral surface of the outer end of the mouth 22, which is opposite to the inner outer track groove 2c of the outer ring 2. The inner ball row 5 is freely sandwiched between the inner outer track groove 2c of the outer ring 2 and the inner track groove 28 of the mouth 22 of the constant velocity joint 20.

[0106] That is, in the wheel bearing device 1A, the constant velocity joint 20 having the inner raceway groove 28 facing the outer raceway groove 2 c of the outer race 2 has a structure that also serves as the inner race.

[0107] The implementation modes of the present invention have been described above, but the present invention is not limited to the above-mentioned implementation modes and is merely exemplified. Naturally, the present invention can be implemented in various forms without departing from the main purpose of the present invention. The scope of the present invention is shown by the contents described in the technical solution, and also includes the meanings equivalent to the contents described in the technical solution and all changes within the scope.

Claims

1. A wheel bearing device, comprising: An outer member having a double row outer track surface on the inner periphery; an inner member, which is composed of a hub having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub, and an inner raceway surface facing the outer raceway surface is formed on the hub and the raceway surface forming member; Double-row rolling elements are freely accommodated between the two track surfaces of the outer member and the inner member; and a sealing device that seals an open end on one axial end side of the annular space formed by the outer member and the inner member, It is characterized in that The sealing device comprises: A core bar, which is embedded in one axial end portion of the outer member; and a sealing member engaged with the core bone, The hub ring has a sealing area portion located at a base of the wheel mounting flange and contacted by the sealing member. The sealing region has an arithmetic mean roughness Ra of 0.2 μm or less and 0.01 μm or more.

2. A wheel bearing device, comprising: An outer member having a double row outer track surface on the inner periphery; an inner member, which is composed of a hub having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub, and an inner raceway surface facing the outer raceway surface is formed on the hub and the raceway surface forming member; Double-row rolling elements are freely accommodated between the two track surfaces of the outer member and the inner member; and a sealing device that seals an open end on one axial end side of the annular space formed by the outer member and the inner member, It is characterized in that The sealing device comprises: A core bar, which is embedded in one axial end portion of the outer member; and a sealing member engaged with the core bone, The hub ring has a sealing area portion located at a base of the wheel mounting flange and contacted by the sealing member. The maximum height roughness Rz of the sealing area portion is 2.5 μm or less and 0.1 μm or more.

3. A wheel bearing device, comprising: An outer member having a double row outer track surface on the inner periphery; an inner member, which is composed of a hub having a wheel mounting flange for mounting a wheel, and a raceway surface forming member connected to the hub, and an inner raceway surface facing the outer raceway surface is formed on the hub and the raceway surface forming member; Double-row rolling elements are freely accommodated between the two track surfaces of the outer member and the inner member; and a sealing device that seals an open end on one axial end side of the annular space formed by the outer member and the inner member, It is characterized in that The sealing device comprises: A core bar, which is embedded in one axial end portion of the outer member; and a sealing member engaged with the core bone, The hub ring has a sealing area portion located at a base of the wheel mounting flange and contacted by the sealing member. The sealing region has an arithmetic mean roughness Ra of 0.2 μm or less and 0.01 μm or more, and a maximum height roughness Rz of 2.5 μm or less and 0.1 μm or more.

4. The wheel bearing device according to any one of claims 1 to 3, characterized in that: The sealing member comprises: a grease lip extending from the core metal toward the inner diameter side and in contact with the sealing area portion; and a side lip extending from the core metal toward the wheel mounting flange side on the outer diameter side of the grease lip and in contact with the sealing area portion. The sealing area portion has a first portion for the grease lip to contact and a second portion for the side lip to contact, The surface roughness of the first portion of the sealing region is greater than the surface roughness of the second portion of the sealing region.

5. The wheel bearing device according to any one of claims 1 to 3, characterized in that: The sealing region has a curved surface shape having a curvature radius of 3.0 mm or more and 6.5 mm or less when viewed from a circumferential direction.

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