Bearing device for wheel

Abstract

In the bearing device for the wheel, the rigidity and the endurance life of the bearing device for the wheel can be ensured, and the increase of friction can be inhibited while the increase of weight is inhibited. A wheel bearing device (1) is configured so that the pitch diameter PCDb of an inner-side ball row (5) or an outer-side ball row (6) and the axial distance c between the center of balls (P1) of the inner-side ball row (5) and the center of balls (P2) of the outer-side ball row (6) satisfy the relationship 3 < PCDb / c < 4, and the pitch diameter PCDb / c satisfies the relationship 3 < PCDb / c < 4. The wheel bearing device (1) is configured so that n-2 < = N is satisfied in the relationship between the maximum number n of balls (7) housed in the inner-side ball row (5) or the outer-side ball row (6) and the number N of balls (7) housed in the inner-side ball row (5) or the outer-side ball row (6), which is the same as the ball row of the maximum number n of housed balls.

Description

Technical Field

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

[0002] Conventionally, there is known a wheel bearing device for rotatably supporting a wheel in a suspension system of an automobile or the like.

[0003] In recent years, the trend toward electrification has been growing in vehicles using wheel bearing devices, driven by fuel regulations and driven by the social context of energy conservation and carbon reduction. Electric vehicles, primarily powered by onboard batteries, are expected to become increasingly popular, but their weight and axle loads are expected to increase compared to gasoline vehicles.

[0004] Generally speaking, as axle load increases, the rotational torque of a wheel bearing assembly increases, necessitating an increase in the size of the wheel bearing assembly for strength reasons. For example, in wheel bearing assemblies used in electric vehicles, the axial distance from the outer side surface of the wheel mounting flange of the hub ring to the inner end of the inner ring is greater than the outer diameter of the outer ring's guide portion, resulting in a tendency toward narrower widths and larger diameters. This tendency is expected to continue.

[0005] Here, in the wheel bearing device, between the multiple rows of outer track grooves of the outer ring as the outer member and the inner track grooves on one side of the hub ring as the inner member and the inner track grooves on the other side of the hub ring, the ball rows are accommodated by retaining multiple balls as rolling bodies respectively.

[0006] Furthermore, the wheel bearing device described in Patent Document 1 comprises an outer ring having a body mounting flange for mounting to a vehicle body and having multiple rows of raceways formed on its inner circumference; a hub ring and an inner ring having a wheel mounting flange for mounting a wheel and having raceway grooves formed on their outer circumferences that oppose the raceway grooves in the outer ring; and multiple rows of rolling elements sandwiched between the outer ring and the raceway grooves in the hub ring and inner ring, respectively. The raceway grooves in the outer ring are hardened by high-frequency quenching to form a hardened layer in the raceway grooves, with the ratio of the effective hardened layer depth to the wall thickness of at least one raceway groove of the outer member being 0.49 or greater. With this configuration, the wheel bearing device of Patent Document 1 prevents quench cracking in the outer ring caused by high-frequency quenching and facilitates lightweighting and compactness of the final product.

[0007] Prior art literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2005-214229 Summary of the Invention

[0010] Problems to be solved by the invention

[0011] Considering the trend toward narrower widths and larger diameters in wheel bearing devices, the number of balls accommodated has increased. For example, if a small number of balls is accommodated, there may be issues with the rigidity and durability of the wheel bearing device. Therefore, increasing the number of balls accommodated is considered. However, increasing the number of balls accommodated increases the weight of the wheel bearing device, and this, in turn, may increase the friction caused by the balls against the raceway grooves of the outer ring, hub ring, and inner ring.

[0012] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel bearing device that can ensure the rigidity and durability of the wheel bearing device and can suppress an increase in friction while suppressing an increase in weight.

[0013] Means for solving problems

[0014] That is, a wheel bearing device comprising:

[0015] As the outer member of the outer ring, it has multiple rows of outer track grooves on the inner circumference;

[0016] an inner member composed of a hub ring and a track groove forming member, wherein the hub ring has an inner track groove on its outer periphery that is opposite to the outer track groove; and the track groove forming member is connected to the hub ring and has an inner track groove on its outer periphery that is opposite to the outer track groove;

[0017] an inner ball row that accommodates balls in a rolling manner between the outer raceway groove and one of the inner raceway grooves; and

[0018] The outer ball row accommodates the balls in a rolling manner between the outer track groove and the inner track groove.

[0019] in,

[0020] The wheel bearing device is configured such that the pitch circle diameter PCDb of the inner ball row or the outer ball row and the axial distance c between the center of the balls of the inner ball row and the center of the balls of the outer ball row satisfy the relationship 3<PCDb / c<4.

[0021] and,

[0022] The wheel bearing device is constructed so that the relationship between the maximum number n of balls that can be accommodated in the inner side ball row or the outer side ball row and the number N of balls accommodated in the inner side ball row or the outer side ball row, which is the same ball row as the ball row that can accommodate the maximum number n, satisfies the relationship n-2≤N.

[0023] Effects of the Invention

[0024] The present invention has the following effects.

[0025] That is, according to the wheel bearing device of the present invention, the rigidity and durability of the wheel bearing device can be ensured, and an increase in friction can be suppressed while suppressing an increase in weight. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a cross-sectional view showing a wheel bearing device according to an embodiment of the present invention.

[0027] Figure 2 This is an enlarged cross-sectional view showing the outer ring of the wheel bearing device.

[0028] Figure 3 2 is a cross-sectional view showing the wheel bearing device.

[0029] Description of reference numerals:

[0030] 1Wheel bearing device

[0031] 2 outer ring

[0032] 2c (Inner side) Outer rail groove

[0033] 2d (outer side) outer track groove

[0034] 2e body mounting flange

[0035] 2f bolt hole

[0036] 3 wheel hubs

[0037] 3a trail steps

[0038] 3b wheel mounting flange

[0039] 3c inner track groove

[0040] 3D bolt holes

[0041] 3e through hole

[0042] 4 inner ring

[0043] 4a inner track groove

[0044] 5 internal side ball rows

[0045] 6 external side ball rows

[0046] 7 balls

[0047] 8 retainers

[0048] 9Inner side sealing member

[0049] 10 External sealing member

[0050] a Thickness of the outer side of the outer ring

[0051] c The axial distance between the center of the balls in the inner ball row and the center of the balls in the outer ball row

[0052] d Depth of the hardened layer of the outer raceway groove on the inner side of the outer ring or the outer raceway groove on the outer side of the outer ring

[0053] eDiameter of the balls in the inner or outer ball row

[0054] h1 Hardened layer of the outer raceway groove on the inner side of the outer ring

[0055] h2 Hardened layer of the outer raceway groove on the outer side of the outer ring

[0056] PCDb Pitch circle diameter of the inner or outer ball row

[0057] Center of the ball in the inner row of balls on P1

[0058] P2 is the center of the balls in the outer ball row. DETAILED DESCRIPTION

[0059] Hereinafter, embodiments of the present invention will be described using the accompanying drawings.

[0060] [Wheel bearing device]

[0061] Figure 1 The wheel bearing device 1 shown is one embodiment of the wheel bearing device of the present invention, and rotatably supports a wheel in a suspension system of a vehicle such as an automobile.

[0062] like Figure 1 and Figure 2 As shown, the wheel bearing device 1 has a so-called third-generation structure, comprising an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, two inner and outer ball rows 5 and 6 as rolling rows, an inner sealing member 9, and an outer sealing member 10. The inner ring 4 is an example of a member forming a raceway groove connected to the hub ring.

[0063] Here, the inner side refers to the vehicle body side of the wheel bearing device 1 when mounted on the vehicle body, and the outer side refers to the wheel side of the wheel bearing device 1 when mounted on the vehicle body. Furthermore, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1, the axially outer side refers to the direction away from the wheel bearing device 1 along the rotation axis X, and the axially inner side refers to the direction toward the wheel bearing device 1 along the rotation axis X. Furthermore, the direction perpendicular to the rotation axis of the wheel bearing device 1 is denoted as the radial direction. In the following description, "cross section" refers to a cross section passing through and parallel to the rotation axis of the wheel bearing device 1.

[0064] The inner circumference of the outer ring 2 is formed with an inner outer raceway groove 2c and an outer outer raceway groove 2d. A vehicle body mounting flange 2e is integrally formed on the outer circumference of the outer ring 2 for attaching the outer ring 2 to a vehicle body member. Bolt holes 2f are provided in the vehicle body mounting flange 2e for inserting fastening members (here, bolts) that fasten the vehicle body member to the outer ring 2.

[0065] A small-diameter step 3a is formed on the inner end of the outer circumference of the hub 3. A wheel mounting flange 3b, extending radially outward, is integrally formed on the outer end of the hub 3 for mounting a wheel. An outer inner track groove 3c is provided on the outer circumference of the hub 3 on the wheel mounting flange 3b, facing the outer outer track groove 2d on the outer ring 2. In other words, the inner track groove 3c is formed by the hub 3 on the outer side of the inner member. The outer inner track groove 3c is an example of an inner track groove that faces the outer inner track groove. A plurality of bolt holes 3d are formed axially through the wheel mounting flange 3b. Multiple hub bolts 3e are press-fitted into each of these bolt holes 3d to secure the hub 3 to the wheel or brake components. The hub 3 also has an axially extending through-hole 3e for connection to a constant velocity universal joint.

[0066] The inner ring 4 is mounted on the small-diameter step 3a of the hub ring 3. The inner ring 4 is press-fitted into the small-diameter step 3a with a predetermined interference fit. The inner ring 4 applies preload to the inner and outer ball rows 5 and 6, which form the rolling element rows. An inner raceway groove 4a is provided on the outer circumference of the inner ring 4, facing the outer raceway groove 2c on the inner side of the outer ring 2. In other words, the inner raceway groove 4a is formed on the inner side of the inner member by the inner ring 4. The inner raceway groove 4a is an example of an inner raceway groove that opposes the outer raceway groove.

[0067] An annular bearing space is formed between the outer ring 2 and the hub ring 3. An outer seal member 10 is fitted into the outer end of the bearing space, acting as a seal to prevent the intrusion of foreign matter such as mud and water. An inner seal member 9 is fitted into the inner end of the bearing space between the outer ring 2 and the inner ring 4, also acting as a seal to prevent the intrusion of foreign matter such as mud and water.

[0068] The inner and outer ball rows 5 and 6, which serve as rolling arrays, are freely accommodated between the two raceway grooves of the outer and inner members. The inner and outer ball rows 5 and 6 are composed of a plurality of balls 7, which serve as rolling elements, held by a retainer 8. The inner ball row 5 is freely sandwiched between the inner outer raceway groove 2c of the outer ring 2 and the inner raceway groove 4a of the inner ring 4. The outer ball row 6 is freely sandwiched between the outer outer raceway groove 2d of the outer ring 2 and the inner raceway groove 3c of the hub 3. In other words, the inner and outer ball rows 5 and 6 are freely accommodated between the two raceway grooves of the outer and inner members.

[0069] In the wheel bearing device 1, a double-row angular contact ball 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. However, the wheel bearing device 1 may also be formed by a double-row tapered roller bearing.

[0070] like Figure 2 As shown, the surface of the outer raceway groove 2c on the inner side of the outer ring 2 is subjected to high-frequency quenching to form a hardened layer h1. The surface of the outer raceway groove 2d on the outer side of the outer ring 2 is subjected to high-frequency quenching to form a hardened layer h2. The depth d of the hardened layer h1 of the outer raceway groove 2c on the inner side of the outer ring 2 and the hardened layer h2 of the outer raceway groove 2d on the outer side of the outer ring 2 are configured to a predetermined depth. In this embodiment, the hardened layers h1 and h2 are configured to the same depth.

[0071] [Regarding the conditions for configuring a wheel bearing device]

[0072] like Figure 1 and Figure 2 As shown, the wheel bearing device 1 is configured to satisfy condition 1.

[0073] With respect to condition 1, the pitch circle diameter PCDb of the inner ball row 5 or the outer ball row 6 and the axial distance c between the center P1 of the ball 7 of the inner ball row 5 and the center P2 of the ball 7 of the outer ball row 6 satisfy the relationship 3<PCDb / c<4. When the pitch circle diameter of the inner ball row 5 is set to PCDbi and the pitch circle diameter of the outer ball row 6 is set to PCDbo, it is more preferable to satisfy the relationship 3<PCDbi / c<4 and 3<PCDbo / c<4. Here, the pitch circle diameter refers to the diameter of the trajectory of the circle described by the centers P1 and P2 of the balls 7 rolling around the rotation axis X. In other words, it is the diameter of a circle whose radius is the radial distance from the rotation axis X to the center of any ball 7.

[0074] As described above, by configuring the wheel bearing device 1 to satisfy Condition 1, the wheel bearing device 1 is configured to be relatively small in the axial direction and relatively large in the radial direction.

[0075] The wheel bearing device 1 is configured to satisfy Condition 2. Regarding Condition 2, the relationship between the maximum accommodable number n of balls 7 in the inner ball row 5 or the outer ball row 6 and the number N of balls 7 accommodated in the inner ball row 5 or the outer ball row 6, which is the same ball row as the ball row with the maximum accommodating number n, satisfies the relationship n-2≤N. Here, the term "the same ball row as the ball row with the maximum accommodating number n" means, for example, that when the maximum accommodating number n is calculated based on the inner ball row 5, the number N of balls 7 accommodated is also set to the number in the inner ball row 5, and when the maximum accommodating number n is calculated based on the outer ball row 6, the number N of balls 7 accommodated is also set to the number in the outer ball row 6, thus satisfying n-2≤N. At least one of the inner ball row 5 and the outer ball row 6 can satisfy n-2≤N, and both the inner ball row 5 and the outer ball row 6 can satisfy n-2≤N. In addition, the maximum number n that can be accommodated refers to the maximum number of balls 7 that can be accommodated in one of the inner ball row 5 or the outer ball row 6 in the wheel bearing device 1 of a specified shape. The maximum number n of balls 7 that can be accommodated in the inner ball row 5 or the outer ball row 6 is determined by the relationship between the diameter e of the balls 7 in the inner ball row 5 or the outer ball row 6 and the pitch circle diameter PCDb of the inner ball row 5 or the outer ball row 6. ≤ The maximum number n that can be accommodated is the largest integer that satisfies the above mathematical formula.

[0076] Thus, by configuring the wheel bearing device 1 to satisfy condition 2, the rigidity and durability of the wheel bearing device 1 can be ensured. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 2, an increase in weight of the wheel bearing device 1 can be suppressed, and an increase in friction caused by the balls 7 with respect to the inner outer raceway groove 2c and the outer outer raceway groove 2d of the outer ring 2, the inner raceway groove 4a of the inner ring 4, and the inner raceway groove 3c of the hub wheel 3 can be suppressed.

[0077] The wheel bearing device 1 is configured to satisfy at least one of the third and fourth conditions.

[0078] Regarding condition 3, the relationship between the thickness a (from the groove bottom to the outer diameter) of the outer raceway groove 2d on the outer side of the outer ring 2 and the pitch circle diameter PCDb of the inner ball row 5 or outer ball row 6 satisfies the relationship 0.07 < (a / PCDb) < 0.08. The thickness a (from the groove bottom to the outer diameter) of the outer raceway groove 2d on the outer side of the outer ring 2 represents the radial length of the inner diameter and outer diameter of the outer ring 2, which intersects an imaginary line Y in the outer raceway groove 2d on the outer side of the outer ring 2. The imaginary line Y is a radially parallel line passing through the center P2 of the ball 7 of the outer ball row 6.

[0079] By thus configuring the wheel bearing device 1 to satisfy condition 3, the thickness a of the outer raceway groove 2d on the outer side of the outer ring 2, from the groove bottom to the outer diameter, can be ensured, thereby ensuring the rigidity of the outer ring 2. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 3, it is possible to prevent an increase in the mass of the outer ring 2 and, consequently, the weight of the wheel bearing device 1, due to an excessive thickness a of the outer raceway groove 2d on the outer side of the outer ring 2, from the groove bottom to the outer diameter.

[0080] Regarding condition 4, the relationship between the depth d of the hardened layer in the outer raceway groove 2c on the inner side of the outer ring 2 or the outer raceway groove 2d on the outer side of the outer ring 2 and the thickness a from the groove bottom to the outer diameter of the outer raceway groove 2d on the outer side of the outer ring 2 satisfies the relationship 0.2 < (d / a) < 0.5. If the depth d of the hardened layer differs between the outer raceway groove 2c on the inner side of the outer ring 2 and the outer raceway groove 2d on the outer side of the outer ring 2, the depth d of the hardened layer may be set to the depth of the hardened layer in the outer raceway groove 2d on the outer side of the outer ring 2.

[0081] Thus, by configuring the wheel bearing device 1 to satisfy condition 4, the depth d of the hardened layer in the outer raceway groove 2c on the inner side of the outer ring 2 or the outer raceway groove 2d on the outer side of the outer ring 2 can be ensured, thereby ensuring the strength of the hardened layer. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 4, quench cracking at the boundary of the hardened layer due to excessive depth d of the hardened layer in the outer raceway groove 2c on the inner side of the outer ring 2 or the outer raceway groove 2d on the outer side of the outer ring 2 can be suppressed.

[0082] Furthermore, the wheel bearing device 1 may be configured to satisfy either Condition 3 or Condition 4. By configuring the wheel bearing device 1 to satisfy either Condition 3 or Condition 4, the thickness a from the groove bottom to the outer diameter of the outer raceway groove 2d on the outer side of the outer ring 2 can be ensured, thereby ensuring the rigidity of the outer ring 2. Furthermore, by configuring the wheel bearing device 1 to satisfy either Condition 3 or Condition 4, the mass of the outer ring 2, which would otherwise be increased due to excessive thickness a from the groove bottom to the outer diameter of the outer raceway groove 2d on the outer side of the outer ring 2, can be prevented, thereby increasing the weight of the wheel bearing device 1. Furthermore, by configuring the wheel bearing device 1 to satisfy either Condition 3 or Condition 4, the depth d of the hardened layer of the inner outer raceway groove 2c or the outer outer raceway groove 2d on the outer side of the outer ring 2 can be ensured, thereby ensuring the strength of the hardened layer. In addition, in this way, by constructing the wheel bearing device 1 to satisfy either condition 3 or condition 4, it is possible to suppress quenching cracks in the boundary portion of the hardened layer due to the excessive depth d of the hardened layer of the outer track groove 2c on the inner side of the outer ring 2 or the outer track groove 2d on the outer side of the outer ring 2.

[0083] The wheel bearing device 1 is configured to satisfy condition 5. Regarding condition 5, the pitch circle diameter PCDb of the inner ball row 5 or the outer ball row 6 satisfies the relationship 60 ≤ PCDb ≤ 120. This relationship may be satisfied by either the inner ball row 5 or the outer ball row 6, or by both.

[0084] Thus, by configuring the wheel bearing device 1 to satisfy condition 5, it is relatively compact in the axial direction and relatively large in the radial direction. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 5, the rigidity and durability of the wheel bearing device 1 can be more reliably ensured in a configuration satisfying condition 2. Furthermore, an increase in weight of the wheel bearing device 1 can be suppressed, and an increase in friction caused by the balls 7 against the inner and outer raceway grooves 2c and 2d of the outer ring 2, the inner raceway grooves 4a of the inner ring 4, and the inner raceway grooves 3c of the hub wheel 3 can be suppressed. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 5, the rigidity of the outer ring 2 can be more reliably ensured in a configuration satisfying condition 3, thereby suppressing an increase in the mass of the outer ring 2 and the weight of the wheel bearing device 1 due to an excessively thick outer raceway groove a. In addition, in this way, by setting the wheel bearing device 1 to a structure that satisfies condition 5, in the structure that satisfies condition 4, the depth d of the hardened layer of the outer track groove 2c on the inner side of the outer ring 2 or the outer track groove 2d on the outer side of the outer ring 2 can be more reliably ensured to ensure the strength of the hardened layer. In addition, it is possible to suppress quenching cracks in the boundary portion of the hardened layer due to the excessive depth d of the hardened layer of the outer track groove 2c on the inner side of the outer ring 2 or the outer track groove 2d on the outer side of the outer ring 2.

[0085] It should be noted that the wheel bearing device 1 in this embodiment is a third-generation structure wheel bearing device 1 in which an outer side track groove 3c is directly formed on the outer periphery of the hub ring 3, but it is not limited to this. It can also be a second-generation structure in which a pair of inner rings 4 are pressed and fixed to the hub ring 3.

[0086] Alternatively, the wheel bearing device 1 may have a fourth-generation structure without the inner ring 4, in which the inner raceway groove opposing the outer raceway groove 2c of the outer ring 2 is formed in a constant velocity universal joint that engages with the through-hole 3f of the hub 3, rather than in the inner ring 4. In this case, the constant velocity universal joint serves as the raceway groove-forming member connected to the hub.

[0087] The fourth generation wheel bearing device having a structure without an inner ring 4 is as follows. Figure 3 The wheel bearing device 1A is configured as shown. The wheel bearing device 1A includes a constant velocity universal joint 50 connected to the hub wheel, and does not include an inner ring 4. The constant velocity universal joint 50 is an example of a raceway groove forming member connected to the hub wheel 3.

[0088] The constant velocity universal joint 50 includes a mouth portion 52 that supports a shaft to which driving force is input from a driving source, and a stem portion 53 that extends outward from the mouth portion 52. The hub 3 has an axially extending through hole 3e, and the stem portion 53 is spline-fitted to the through hole 3e.

[0089] An inner raceway groove 58 is formed on the outer peripheral surface of the outer end portion of the mouth portion 52, facing the outer raceway groove 2c on the inner side of the outer ring 2. The inner ball row 5 is freely rollable between the outer raceway groove 2c on the inner side of the outer ring 2 and the inner raceway groove 58 of the mouth portion 52 of the constant velocity universal joint 50.

[0090] In other words, in the wheel bearing device 1A, the constant velocity universal joint 50 having the inner raceway groove 58 facing the outer raceway groove 2 c on the inner side of the outer race 2 serves also as the inner race.

[0091] The above describes the embodiments of the present invention, but the present invention is not limited to such embodiments and is merely illustrative. Of course, it can be further implemented in various ways within the scope of the present invention. The scope of the present invention is shown by the description of the scope of the claims, and also includes the equivalent meanings recorded in the scope of the claims and all changes within the scope.

Claims

1. A wheel bearing device comprising: As the outer member of the outer ring, it has multiple rows of outer track grooves on the inner circumference; an inner member composed of a hub ring and a track groove forming member, wherein the hub ring has an inner track groove on its outer periphery that is opposite to the outer track groove; and the track groove forming member is connected to the hub ring and has an inner track groove on its outer periphery that is opposite to the outer track groove; an inner ball row that accommodates balls in a rolling manner between the outer raceway groove and one of the inner raceway grooves; and The outer ball row accommodates the balls in a rolling manner between the outer track groove and the inner track groove. in, The wheel bearing device is configured such that the pitch circle diameter PCDb of the inner ball row or the outer ball row and the axial distance c between the center of the balls of the inner ball row and the center of the balls of the outer ball row satisfy the relationship 3<PCDb / c<4. and, The wheel bearing device is constructed so that the relationship between the maximum number n of balls that can be accommodated in the inner side ball row or the outer side ball row and the number N of balls accommodated in the inner side ball row or the outer side ball row, which is the same ball row as the ball row that can accommodate the maximum number n, satisfies the relationship n-2≤N.

2. The wheel bearing device according to claim 1, wherein: The wheel bearing device is configured to satisfy any one of the following relationships: The relationship between the thickness a from the groove bottom to the outer diameter of the outer raceway groove on the outer side of the outer ring and the pitch circle diameter PCDb of the inner ball row or the outer ball row satisfies the relationship 0.07<(a / PCDb)<0.

08. The relationship between the depth d of the hardened layer of the outer raceway groove and the thickness a of the outer raceway groove on the outer side of the outer ring from the groove bottom to the outer diameter satisfies the relationship 0.2<(d / a)<0.

5.

3. The wheel bearing device according to claim 1, wherein: The wheel bearing device is configured such that the relationship between the thickness a from the groove bottom to the outer diameter of the outer raceway groove on the outer side of the outer ring and the pitch circle diameter PCDb of the inner side ball row or the outer side ball row satisfies the relationship 0.07<(a / PCDb)<0.

08. and, The wheel bearing device is configured such that the relationship between the depth d of the hardened layer of the outer raceway groove and the thickness a of the outer raceway groove from the groove bottom to the outer diameter on the outer side of the outer ring satisfies the relationship 0.2<(d / a)<0.

5.

4. The wheel bearing device according to claim 1, wherein: The wheel bearing device is configured so that the pitch circle diameter PCDb of the inner ball row or the outer ball row satisfies the relationship of 60≤PCDb≤120.

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