Wheel bearing device

Abstract

To provide a wheel bearing device capable of ensuring rigidity and durability, and capable of preventing increase of friction while preventing a weight from increasing.SOLUTION: A wheel bearing device 1 is configured so that a pitch circle diameter PCDb of an inner side ball row 5 or an outer side ball row 6, and an axial distance c between a center P1 of a ball in the inner side ball row 5 and a center P2 of a ball in the outer side ball row 6 satisfy the relation: 3<PCDb / c<4, and the maximum number n of balls 7 that can be accommodated in the inner side ball row 5 or the outer side ball row 6, and the number N of balls 7 accommodated in the inner side ball row 5 or the outer side ball row 6, which is the same ball row as the ball row with the maximum number n satisfy the relation: n-2≤N.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] 2. Description of the Related Art Wheel bearing devices that rotatably support wheels in suspension systems for automobiles and the like are known.

[0003] In recent years, fuel regulations have been imposed on vehicles that use wheel bearing devices in response to social trends such as energy conservation and decarbonization, and the trend toward electrification is progressing. Electric vehicles, which are primarily powered by on-board batteries and are expected to become more popular in the future, tend to be heavier than gasoline-powered vehicles, and their axle loads tend to increase.

[0004] Generally, as the axle load increases, the rotational torque of the wheel bearing device increases, and from the standpoint of strength, the wheel bearing device needs to be made larger. For example, in wheel bearing devices used in electric vehicles, the axial distance from the outer side surface of the wheel mounting flange of the hub wheel to the inner end of the inner ring is larger than the outer diameter of the pilot portion of the outer ring, and there is a tendency for widths to be narrow and large, and this trend toward narrow widths and large diameters is expected to continue.

[0005] Here, in the wheel bearing device, a row of balls is accommodated between the double row of outer raceway grooves of the outer ring, which is the outer member, and one inner raceway groove of the hub ring, which is the inner member, and the other inner raceway groove of the hub ring, by retaining a plurality of balls, which are rolling elements, with the balls held by a cage.

[0006] The wheel bearing device described in Patent Document 1 comprises an outer ring having a body mounting flange for mounting to the vehicle body and with double-row raceways formed on its inner circumference, a hub ring and an inner ring having a wheel mounting flange for mounting a wheel and with raceway grooves formed on their outer circumferences that face the raceway grooves of the outer ring, and double-row rolling elements interposed between the raceway grooves of the outer ring, the hub ring, and the inner ring, the raceway grooves of the outer ring are hardened by induction hardening to form a hardened layer in the raceway groove, and the ratio of the effective hardened layer depth to the wall thickness at the bottom of at least one of the raceway grooves of the outer member is 0.49 or more. The wheel bearing device of Patent Document 1 configured in this way prevents hardening cracks in the outer ring due to induction hardening and makes it easy to achieve a lightweight and compact final product. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-214229 Summary of the Invention [Problem to be solved by the invention]

[0008] As the wheel bearing device tends to have a narrower width and a larger diameter, it is conceivable that the number of balls accommodated will increase. For example, if the number of balls accommodated is small, problems may arise in the rigidity and durability of the wheel bearing device, so it is conceivable to increase the number of balls accommodated. However, an increase in the number of balls accommodated will increase the weight of the wheel bearing device, and further, there is a risk that the friction caused by the balls against the raceway grooves of the outer ring, hub ring, and inner ring will increase.

[0009] The present invention has been made in consideration of the above-mentioned circumstances, and has as its object to provide a wheel bearing device that can ensure the rigidity and durable life of the wheel bearing device, and that can suppress an increase in weight while suppressing an increase in friction. [Means for solving the problem]

[0010] That is, an outer member which is an outer ring having a double row of outer raceways on the inner circumference, a hub ring provided with one inner raceway facing the outer raceway on the outer circumference, a raceway groove forming member connected to the hub ring and having the other inner raceway facing the outer raceway on the outer circumference, and an inner member composed of: an inner side ball row in which balls are rotatably accommodated between the outer raceway and one of the inner raceways, and an outer side ball row in which balls are rotatably accommodated between the outer raceway and the other inner raceway, and a wheel bearing device comprising: Regarding the pitch circle diameter PCDb of the inner side ball row or the outer side ball row, and the axial distance c between the center of the balls in the inner side ball row and the center of the balls in the outer side ball row, it is configured to satisfy the relationship of 3 < PCDb / c < 4, and In the relationship between the maximum number of balls n 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 with the maximum number of balls n, it is configured to satisfy the relationship of n - 2 ≤ N.

Advantages of the Invention

[0011] As an effect of the present invention, the following effects are achieved. That is, according to the wheel bearing device of the present invention, it is possible to ensure the rigidity and durability life of the wheel bearing device, and it is also possible to suppress an increase in friction while suppressing an increase in weight.

Brief Description of the Drawings

[0012] [Figure 1] The cross-sectional view which shows the wheel bearing device which concerns on embodiment of this invention. [Figure 2] [[ID=3SS]] [Figure 3] The enlarged cross-sectional view which shows the outer ring of a wheel bearing device similarly. [Figure 3]FIG.

[0013] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0014] [Wheel bearing device] A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and supports a wheel rotatably in a suspension system of a vehicle such as an automobile.

[0015] 1 and 2, the wheel bearing device 1 has a configuration known as a third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, an inner seal member 9, and an outer seal member 10. The inner ring 4 is an example of a raceway groove forming member connected to the hub ring.

[0016] Here, the inner side refers to the vehicle body side of the wheel bearing device 1 when it is attached to the vehicle body, and the outer side refers to the wheel side of the wheel bearing device 1 when it is attached to the vehicle body. Also, the axial direction refers to the direction along the rotation axis X of the wheel bearing device 1, the axially outward direction refers to the direction away from the wheel bearing device 1 along the rotation axis X, and the axially inward direction refers to the direction approaching the wheel bearing device 1 along the rotation axis X. Also, the direction perpendicular to the rotation axis of the wheel bearing device 1 is referred to as the radial direction. Also, in the following description, a "cross section" refers to 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.

[0017] An inner-side outer raceway groove 2c and an outer-side outer raceway groove 2d are formed on the inner peripheral surface of the outer ring 2. A vehicle body mounting flange 2e for mounting the outer ring 2 to a vehicle body member is integrally formed on the outer peripheral surface of the outer ring 2. Bolt holes 2f are provided in the vehicle body mounting flange 2e, into which fastening members (here, bolts) are inserted to fasten the outer ring 2 to the vehicle body member.

[0018] The inner end of the outer peripheral surface of the hub ring 3 is formed with a small-diameter step 3a that is smaller in diameter than the outer end. A wheel mounting flange 3b that extends radially outward is integrally formed with the outer end of the hub ring 3 for mounting a wheel. An outer-side inner raceway groove 3c is provided on the wheel mounting flange 3b on the outer peripheral surface of the hub ring 3, facing the outer-side outer raceway groove 2d of the outer ring 2. In other words, the inner raceway groove 3c is formed by the hub ring 3 on the outer side of the inner member. The outer-side inner raceway groove 3c is an example of one of the inner raceway grooves facing the outer raceway groove. A plurality of bolt holes 3d are formed axially through the wheel mounting flange 3b. A plurality of hub bolts 3e are press-fitted into the plurality of bolt holes 3d to fasten the hub ring 3 to a wheel or brake component. The hub ring 3 has a through hole 3e that passes axially through for connection to a constant velocity universal joint.

[0019] The inner ring 4 is provided on the small diameter step 3a of the hub ring 3. The inner ring 4 is press-fitted into the small diameter step 3a via a predetermined interference. The inner ring 4 applies preload to the inner ball row 5 and outer ball row 6, which are rolling rows. An inner-side inner raceway groove 4a is provided on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway groove 2c of the outer ring 2. In other words, the inner ring 4 defines the inner raceway groove 4a on the inner side of the inner member. The inner raceway groove 4a is an example of the other inner raceway groove facing the outer raceway groove.

[0020] A bearing space, which is an annular space, is formed between the outer ring 2 and the hub ring 3. An outer seal member 10, which is a sealing device, is fitted into the outer end of the bearing space to prevent the intrusion of foreign matter such as muddy water. An inner seal member 9, which is also a sealing device, is fitted into the inner end of the bearing space between the outer ring 2 and the inner ring 4 to prevent the intrusion of foreign matter such as muddy water.

[0021] The inner ball row 5 and outer ball row 6, which are rolling rows, are rollably housed between the raceway grooves of the outer member and the inner member. The inner ball row 5 and outer ball row 6 are formed by a plurality of balls 7, which are rolling elements, held in a cage 8. The inner ball row 5 is rollably sandwiched between the outer raceway groove 2c on the inner side of the outer ring 2 and the inner raceway groove 4a of the inner ring 4. The outer ball row 6 is rollably sandwiched between the outer raceway groove 2d on the outer side of the outer ring 2 and the inner raceway groove 3c of the hub ring 3. In other words, the inner ball row 5 and outer ball row 6 are rollably housed between the raceway grooves of the outer member and the inner member.

[0022] In the wheel bearing device 1, a double-row angular contact ball bearing is formed by the outer ring 2, hub ring 3, inner ring 4, inner ball row 5, and outer ball row 6. However, the wheel bearing device 1 may also be formed by a double-row tapered roller bearing.

[0023] As shown in Fig. 2, the surface of the outer raceway groove 2c on the inner side of the outer ring 2 is heat treated by induction hardening to form a hardened layer h1. The surface of the outer raceway groove 2d on the outer side of the outer ring 2 is heat treated by induction hardening to form a hardened layer h2. 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 each have a predetermined depth d. In this embodiment, the hardened layers h1 and h2 are configured to the same depth.

[0024] [Conditions for configuring a wheel bearing device] As shown in FIG. 1 or FIG. 2, the wheel bearing device 1 is configured to satisfy Condition 1. Condition 1 is such that, with respect to the pitch circle diameter PCDb of the inner side ball row 5 or the outer side ball row 6, and the axial distance c between the center P1 of the ball 7 of the inner side ball row 5 and the center P2 of the ball 7 of the outer side ball row 6, the relationship 3 < PCDb / c < 4 is satisfied. When the pitch circle diameter of the inner side ball row 5 is PCDbi and the pitch circle diameter of the outer side ball row 6 is PCDbo, it is more preferable to satisfy the relationships 3 < PCDbi / c < 4 and 3 < PCDbo / c < 4. Here, the pitch circle diameter is the diameter of the locus of the centers P1, P2 of the balls 7 rolling about the rotation axis X. That is, it is the diameter of a circle with the radial distance from the rotation axis X to the center of any ball 7 as the radius.

[0025] Thus, by configuring the wheel bearing device 1 to satisfy Condition 1, it is configured to be relatively small in the axial direction and relatively large in the radial direction.

[0026] The wheel bearing device 1 is configured to satisfy Condition 2. Condition 2 satisfies the relationship n-2≦N between the maximum number n of balls 7 that can be accommodated 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 a ball row similar to the ball row with the maximum number n. Here, a ball row similar to the ball row with the maximum capacity n is one that satisfies n-2≦N, for example, when the maximum capacity n is calculated from the inner ball row 5, the number N of balls 7 that can be accommodated is also the number in the inner ball row 5, and when the maximum capacity n is calculated from the outer ball row 6, the number N of balls 7 that can be accommodated is also the number in the outer ball row 6. At least one of the inner ball row 5 and the outer ball row 6 may satisfy n-2≦N, or both the inner ball row 5 and the outer ball row 6 may satisfy n-2≦N. The maximum number n that can be accommodated refers to the maximum number of balls 7 that can be accommodated in either the inner ball row 5 or the outer ball row 6 in a wheel bearing device 1 of a predetermined shape. The maximum number n of balls 7 that can be accommodated in the inner ball row 5 or the outer ball row 6 satisfies 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, where n≦(360 / 2arctan((e / 2) / √((PCDb / 2) 2 -(e / 2) 2 The maximum capacity n is the largest integer that satisfies the above formula.

[0027] In this way, by configuring the wheel bearing device 1 to satisfy condition 2, it is possible to ensure the rigidity and durable life of the wheel bearing device 1. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 2, it is possible to suppress an increase in the weight of the wheel bearing device 1, while suppressing an increase in friction caused by the balls 7 against the inner-side outer raceway groove 2c and outer-side 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 ring 3.

[0028] The wheel bearing device 1 is configured to satisfy at least one of the conditions 3 and 4.

[0029] Condition 3 is that the relationship between the thickness a from the groove bottom to the outer diameter of the outer outer grooved raceway 2d on the outer ring 2 and the pitch circle diameter PCDb of the inner ball row 5 or the outer ball row 6 satisfies the following relationship: 0.07<(a / PCDb)<0.08. The thickness a from the groove bottom to the outer diameter of the outer outer grooved raceway 2d on the outer ring 2 represents the radial length between the inner diameter and the outer diameter of the outer ring 2 that intersects with imaginary line Y at the outer outer grooved raceway 2d on the outer ring 2. Imaginary line Y is a line that passes through the center P2 of the ball 7 in the outer ball row 6 and is parallel to the radial direction.

[0030] In this way, by configuring the wheel bearing device 1 to satisfy condition 3, it is possible to ensure the thickness a from the groove bottom to the outer diameter of the outer outer raceway groove 2d on the outer side of the outer ring 2, 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 weight of the wheel bearing device 1 due to an increase in the mass of the outer ring 2 caused by an excessively large thickness of the thickness a from the groove bottom to the outer diameter of the outer outer raceway groove 2d on the outer side of the outer ring 2.

[0031] Condition 4 is that the relationship between the hardened layer depth d of the inner-side outer groove raceway 2c of the outer ring 2 or the outer-side outer groove raceway 2d of the outer ring 2 and the thickness a from the groove bottom to the outer diameter of the outer-side outer groove raceway 2d of the outer ring 2 satisfies 0.2<(d / a)<0.5. If the hardened layer depth d differs between the inner-side outer groove raceway 2c of the outer ring 2 and the outer-side outer groove raceway 2d of the outer ring 2, the hardened layer depth d may be taken as the hardened layer depth of the outer-side outer groove raceway 2d of the outer ring 2.

[0032] In this way, by configuring the wheel bearing device 1 to satisfy condition 4, it is possible to ensure the depth d of the hardened layer of the inner-side outer raceway groove 2c of the outer ring 2 or the outer raceway groove 2d on the outer side of the outer ring 2, thereby ensuring the strength of the hardened layer. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 4, it is possible to prevent quench cracks from occurring at the boundary portion of the hardened layer due to the depth d of the hardened layer of the inner-side outer raceway groove 2c of the outer ring 2 or the outer raceway groove 2d on the outer side of the outer ring 2 being excessively deep.

[0033] The wheel bearing device 1 can also be configured to satisfy both condition 3 and condition 4. By configuring the wheel bearing device 1 to satisfy both condition 3 and condition 4 in this way, the thickness a from the groove bottom to the outer diameter of the outer 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. By configuring the wheel bearing device 1 to satisfy both condition 3 and condition 4 in this way, it is possible to suppress an increase in the mass of the outer ring 2 and an increase in the weight of the wheel bearing device 1 due to an excessively large thickness of the thickness a from the groove bottom to the outer diameter of the outer outer raceway groove 2d on the outer side of the outer ring 2. By configuring the wheel bearing device 1 to satisfy both condition 3 and condition 4 in this way, it is possible to ensure the depth d of the hardened layer of the inner outer raceway groove 2c of the outer ring 2 or the outer outer raceway groove 2d on the outer side of the outer ring 2, thereby ensuring the strength of the hardened layer. Furthermore, by configuring the wheel bearing device 1 to satisfy both condition 3 and condition 4 in this way, it is possible to prevent quench cracks from occurring at the boundary of the hardened layer due to the depth d of the hardened layer of 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 being excessively deep.

[0034] The wheel bearing device 1 is configured to satisfy condition 5. Condition 5 satisfies the relationship 60≦PCDb≦120 for the pitch circle diameter PCDb of the inner ball row 5 or the outer ball row 6. Either one of the inner ball row 5 or the outer ball row 6 may satisfy this relationship, or both may satisfy it.

[0035] By configuring the wheel bearing device 1 to satisfy condition 5 in this way, it is configured to be relatively small in the axial direction and relatively large in the radial direction. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 5 in this way, it is possible to more reliably ensure the rigidity and durable life of the wheel bearing device 1 in a configuration that satisfies condition 2, and to suppress an increase in friction caused by the balls 7 against the inner-side outer raceway groove 2c and outer-side 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 ring 3, while suppressing an increase in the weight of the wheel bearing device 1. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 5 in this way, it is possible to more reliably ensure the thickness a of the outer-side portion of the outer ring 2 to ensure the rigidity of the outer ring 2 in a configuration that satisfies condition 3, and to suppress an increase in the weight of the wheel bearing device 1 that would otherwise be caused by an increase in the mass of the outer ring 2 due to an excessively large thickness a of the outer-side portion of the outer ring 2. Furthermore, by configuring the wheel bearing device 1 to satisfy condition 5 in this way, in a configuration that satisfies condition 4, the depth d of the hardened layer of 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 more reliably ensured to ensure the strength of the hardened layer, and it is also possible to prevent quench cracks from occurring at the boundary portion of the hardened layer due to the depth d of the hardened layer of 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 being excessively deep.

[0036] In this embodiment, the wheel bearing device 1 is configured as a wheel bearing device 1 of a third-generation structure in which the outer raceway groove 3c is formed directly on the outer periphery of the hub wheel 3, but this is not limited to this and it may also be a second-generation structure in which a pair of inner rings 4 are press-fitted and fixed to the hub wheel 3.

[0037] Furthermore, instead of forming an inner raceway groove opposing the outer raceway groove 2c of the outer ring 2 in the inner ring 4, the wheel bearing device 1 can also have a fourth-generation structure in which the inner raceway groove is formed in a constant velocity universal joint that fits into the through hole 3f of the hub ring 3, and no inner ring 4 is provided. In this case, the constant velocity universal joint becomes a raceway groove forming member connected to the hub ring.

[0038] A wheel bearing device of the fourth generation structure that does not have an inner ring 4 can be configured, for example, as a wheel bearing device 1A shown in Figure 3. The wheel bearing device 1A has a constant velocity universal joint 50 connected to the hub wheel, and does not have 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.

[0039] Constant velocity universal joint 50 includes a mouth portion 52 that supports a shaft to which driving force is input from a drive source, and a stem portion 53 that extends toward the outer side from mouth portion 52. Hub wheel 3 has a through hole 3e that passes through in the axial direction, and through hole 3e and stem portion 53 are spline-fitted.

[0040] An inner raceway groove 58 is formed on the outer peripheral surface of the outer end 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 rollably sandwiched 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.

[0041] That is, in the wheel bearing device 1A, the constant velocity universal joint 50 having the inner raceway groove 58 facing the outer raceway groove 2c on the inner side of the outer ring 2 also serves as the inner ring.

[0042] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0043] 1 Wheel bearing device 2 outer ring 2c (inner side) outer raceway groove 2d (Outer side) outer raceway groove 2e Body mounting flange 2f bolt hole 3 Hub Wheel 3a Small diameter stepped section 3b Wheel mounting flange 3c Inner raceway groove 3d bolt holes 3e Through hole 4. Inner Circle 4a Inner raceway groove 5 Inner ball row 6 Outer ball row 7 Ball 8 Cage 9 Inner seal member 10 Outer seal member a Thickness of the outer side of the outer ring c Axial distance between the center of the ball in the inner ball row and the center of the ball in the outer ball row d Depth of 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 e Diameter of the balls in the inner or outer ball row h1 Hardened layer of the outer raceway groove on the inner side of the outer ring h2 Hardened layer of the outer raceway groove on the outer side of the outer ring PCDb Pitch circle diameter of inner or outer ball row P1 Center of the inner ball row P2 Center of outer ball row

Claims

1. an outer member which is an outer ring having double-row outer raceway grooves on its inner periphery; an inner member comprising: a hub wheel having, on its outer periphery, one inner raceway groove that faces the outer raceway groove; and a raceway groove forming member connected to the hub wheel and having, on its outer periphery, the other inner raceway groove that faces the outer raceway groove; an inner ball row in which balls are rollably accommodated between the outer raceway groove and one of the inner raceway grooves; an outer ball row in which balls are rollably accommodated between the outer raceway groove and the other inner raceway groove, a pitch circle diameter PCDb of the inner ball row or the outer ball row and a distance c in the axial direction between the center of a ball in the inner ball row and the center of a ball in the outer ball row are configured to satisfy the relationship 3<PCDb / c<4, and, A wheel bearing device configured so that the relationship between the maximum number n of balls that can be accommodated in the inner ball row or the outer ball row and the number N of balls that can be accommodated in the inner ball row or the outer ball row, which is a ball row similar to the ball row with the maximum number n that can be accommodated, satisfies the relationship n-2≦N.

2. a thickness a of the outer raceway groove on the outer side of the outer ring from a groove bottom to the outer diameter and a pitch circle diameter PCDb of the inner side ball row or the outer side ball row satisfy the relationship 0.07<(a / PCDb)<0.08; a relationship between a depth d of the hardened layer of the outer raceway groove and a thickness a of the outer raceway groove on the outer side of the outer ring from the groove bottom to the outer diameter, wherein the relationship is 0.2<(d / a)<0.5 2. The wheel bearing device according to claim 1, wherein the wheel bearing device is configured to satisfy any one of the following relationships:

3. a thickness a of the outer raceway groove on the outer side of the outer ring from a groove bottom to the outer diameter and a pitch circle diameter PCDb of the inner side ball row or the outer side ball row satisfy the relationship 0.07<(a / PCDb)<0.08, and, 2. The wheel bearing device according to claim 1, wherein a depth d of the hardened layer of the outer raceway groove and a thickness a of the outer raceway groove on the outer side of the outer ring from a groove bottom to an outer diameter satisfy the relationship 0.2<(d / a)<0.

5.

4. 2. The wheel bearing device according to claim 1, wherein a pitch circle diameter PCDb of the inner ball row or the outer ball row satisfies the relationship 60≦PCDb≦120.

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