CN115807814A

CN115807814A - Bearing device for wheel

Info

Publication number: CN115807814A
Application number: CN202211072237.1A
Authority: CN
Inventors: 犬塚圭; 中川友和
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2021-09-16
Filing date: 2022-09-02
Publication date: 2023-03-17
Also published as: CN218294198U; JP2023043695A

Abstract

The invention provides a bearing device for a wheel, which has a metal flow line (grain flow) with an angle below a specified value relative to a track surface even if the interval of a plurality of rows of track rings is increased. The wheel bearing device (1) comprises: an outer ring (2) having a plurality of outer raceway surfaces on an inner peripheral surface thereof; a hub (3) and an inner ring (4) having a plurality of inner raceway surfaces formed on an outer circumferential surface thereof and opposed to the plurality of outer raceway surfaces; and a plurality of rows of balls rollably housed between the outer ring (2) and both raceway surfaces of the hub (3) and the inner ring (4). When a moment load M of + -0.2 kNm is applied to the hub (3) with respect to the outer ring (2), all of the balls in the plurality of rows are in contact with both raceway surfaces.

Description

Bearing device for wheel

Technical Field

The present invention relates to a wheel bearing device and a vehicle having the wheel bearing device.

Background

There is known a wheel bearing device for rotatably supporting a wheel. The wheel bearing device is configured such that a hub, which is an inner member connected to a wheel, is rotatably supported by an outer ring, which is an outer member, via rolling elements. The wheel bearing device is configured to apply a preload to rolling elements that rotatably support the hub in order to ensure rigidity at least equal to or greater than a predetermined level. The wheel bearing device can suppress the inclination of the inner ring relative to the outer ring due to the moment load by applying the preload.

The wheel bearing device secures rigidity by applying a preload such that a rigidity value (Nm/deg) is within a predetermined value, the rigidity value being a proportion of a tilt of the hub with respect to the outer ring when a predetermined moment load is applied to the hub. However, the wheel bearing device supports the hub with a plurality of rolling elements. Thus, the rigidity value of the wheel support bearing device under a constant preload is not constant. In particular, the rigidity value of the wheel support bearing device with a low preload fluctuates even under a moment load during a straight running and a cornering at a low speed. That is, the rigidity value of the wheel support bearing device with a low preload changes with a relatively small moment load. The wheel support bearing device with such a low preload has an inflection point that is a value of a moment load in which a rigidity value changes, and thus may affect the steering safety of the vehicle during low-speed running. Therefore, there has been proposed a wheel bearing device that suppresses an influence of the variation in the rigidity value on the steering safety of the vehicle. For example, as described in patent document 1.

The wheel bearing device described in patent document 1 includes a pressing member between a shaft portion and a hub of a constant velocity universal joint of a vehicle. The pressing member is a member capable of pressing the boss in the axial direction. The pressing member controls the pressing force by the control unit. The control unit determines the pressing force from the moment load according to the traveling state of the vehicle based on a predetermined correspondence relationship between the moment load applied to the wheel bearing device and the pressing force of the pressing member. The control unit presses the hub with the determined pressing force to correct the inclination of the hub. Thus, the wheel support bearing device described in patent document 1 can maintain the rigidity value at a constant value.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2017-114375

Disclosure of Invention

Technical problem to be solved by the invention

In the wheel support bearing device disclosed in patent document 1, the inclination of the hub with respect to the moment load is corrected by the pressing member, and the rigidity value is maintained at a constant value. However, in the wheel support bearing device, the characteristics of the plurality of rolling elements that rotatably support the hub with respect to the moment load do not change. That is, the wheel bearing device described in patent document 1 maintains the rigidity value of the wheel to be constant by the pressing member. Therefore, in the case of the wheel bearing device with a low preload, there is a possibility that the steering safety of the vehicle during low-speed straight running or low-speed cornering is affected by variation in the rigidity value of the hub with respect to the outer ring.

The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a wheel bearing device capable of suppressing a variation in rigidity value under a low moment load and improving the steering safety of a vehicle during low-speed straight running or low-speed cornering, and a vehicle including the wheel bearing device.

Technical solution for solving technical problem

That is, a first aspect is a wheel bearing apparatus including: an outer member having, on an inner peripheral surface thereof, a plurality of annular outer raceway surfaces having the same axis; an inner member having a plurality of inner raceway surfaces formed on an outer peripheral surface thereof, the inner raceway surfaces being opposed to the plurality of outer raceway surfaces; and a plurality of rows of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member. When a moment load of ± 0.2kNm is applied to the inner member with respect to the outer member (that is, when a moment load of ± 0.2kNm is applied to the inner member with respect to the outer member), all of the rolling elements in the plural rows contact the raceway surfaces.

That is, in the second aspect, the preload that is the minimum preload required to bring all of the multi-row rolling elements into contact with the raceway surfaces when a moment load of ± 0.2kNm is applied to the inner member with respect to the outer member (i.e., with reference to the outer member) is taken as the preload lower limit value.

That is, the third aspect is a vehicle having the wheel bearing device of the first and second aspects.

That is, in the fourth aspect, the wheel support bearing device supports a steered wheel of the vehicle.

Effects of the invention

The following effects are exhibited as the effects of the present invention.

That is, in the first aspect, in the wheel bearing device, when a moment load of ± 0.2kNm, which is a low moment load, is applied to the hub, preload is applied to all of the rolling elements in contact with the outer raceway surface and the inner raceway surface, and therefore, a state in which all of the multi-row rolling elements are in contact with the outer raceway surface and the inner raceway surface is maintained. Of course, even when a moment load of less than 0.2kNm is applied to the hub, the wheel bearing device maintains the state in which all of the rolling elements in the plurality of rows are in contact with the outer raceway surface and the inner raceway surface. Therefore, the wheel support bearing assembly can maintain the rigidity value within a certain range in a low moment load range centered on a moment load of ± 0.2 kNm. This suppresses variation in the rigidity value under a low moment load, and improves the operational safety of the wheels during low-speed straight running or low-speed cornering.

In a second aspect, in the wheel bearing apparatus, when a moment load of ± 0.2kNm is applied to the hub as a low moment load, a preload is applied to the rolling elements with a minimum preload required to bring all of the multi-row rolling elements into contact with the raceway surfaces being set as a preload lower limit value. Therefore, the wheel support bearing device can be set to a preload value that maintains the rigidity value within a certain range within a low moment load range centered on a moment load of ± 0.2 kNm. This suppresses variation in the rigidity value under a low moment load, and improves the operational safety of the wheels during low-speed straight running or low-speed cornering.

In the third and fourth aspects, the vehicle having the wheel bearing device can improve the steering safety during low-speed straight running or low-speed cornering.

[ rigidity value ]

In the present specification, the stiffness value (Nm/deg) is a moment load required to tilt the hub relative to the outer ring by a unit angle in the wheel bearing device. Alternatively, the rigidity value is a ratio of a moment load applied to the hub to a tilt of the hub with respect to the outer ring when the moment load is applied.

[ Low-speed straight-line running or Low-speed cornering ]

In the present specification, the low-speed straight running or the low-speed turning running means a running state in which the speed of the straight running or the turning running of the vehicle is about 20km per hour.

[ Low moment load ]

In the present specification, the low moment load means a moment load applied to the wheel bearing device when the vehicle is running straight at a low speed or running in a curve at a low speed. The low moment load is, for example, a moment load centered at ± 0.2 kNm.

Drawings

Fig. 1 is a perspective view showing an overall structure of a wheel bearing device according to an embodiment of the present invention.

Fig. 2 is a sectional view showing an overall structure of a wheel bearing device according to an embodiment of the present invention.

Fig. 3 is a cross-sectional view showing a structure for applying a moment load to a hub of a wheel bearing device according to an embodiment of the present invention.

Fig. 4 is a table showing the number of rolling elements that receive a load when a moment load of 0.1kNm and a moment load of 0.2kNm are applied to the wheel bearing device for each preload.

Fig. 5 is a graph showing a relationship between a moment load and a hub inclination angle of the wheel bearing apparatus to which a specific low preload is applied.

Fig. 6 is a graph showing a relationship between a moment load and a wheel hub inclination angle of the wheel bearing device to which a specific high preload is applied.

Description of reference numerals

1. Bearing device for wheel

2. Outer ring

2a inner side opening

2b outer side opening

2c first outer raceway surface

2d second outer orbital surface

2e vehicle body mounting flange

2g guide part

3. Wheel hub

3a small diameter step part

3b riveted part

3c wheel mounting flange

3d hub bolt

3e sealing sliding surface

3f second inner raceway surface

4. Inner ring

4a first inner raceway surface

5. Ball row on inner side

6. Ball row on outer side

7. Backside sealing member

8. Outer surface side sealing member

9. Ball bearing

M moment load

F force

L distance

P inflection point

Detailed Description

Hereinafter, a wheel bearing device 1 as an embodiment of a wheel bearing device according to the present invention will be described with reference to fig. 1 and 2. Fig. 1 is a perspective view showing the overall structure of a wheel bearing device 1. Fig. 2 is a sectional view showing the entire structure of the wheel bearing device 1.

As shown in fig. 1, a wheel bearing device 1 is a device for rotatably supporting a wheel in a suspension device of a vehicle such as an automobile. In the present embodiment, the wheel bearing device 1 is a wheel bearing device for a driven wheel. The wheel bearing device 1 is a wheel bearing device for a steered wheel that supports a steered wheel of a vehicle, not shown.

The wheel bearing device 1 includes an outer ring 2 as an outer member, a hub 3 and an inner ring 4 as inner members, 2 rows of inner ball rows 5, an outer ball row 6, an inner seal member 7, and an outer seal member 8. Here, the back side represents the vehicle body side of the wheel bearing device 1 when attached to the vehicle body, and the outer side represents the wheel side of the wheel bearing device 1 when attached to the vehicle body. The axial direction indicates a direction along the rotation axis of the wheel bearing device 1.

As shown in fig. 2, the outer ring 2, which is an outer member, supports inner members (a hub 3 and an inner ring 4). The outer ring 2 is made of a medium-high carbon steel containing 0.40 to 0.80wt% of carbon, such as S53C, which is formed in a substantially cylindrical shape. The outer ring 2 has a back surface side opening 2a at a back surface side end portion into which the back surface side seal member 7 is fitted. The outer ring 2 has an outer surface side opening 2b at an outer surface side end portion, into which the outer surface side seal member 8 is fitted.

The outer ring 2 has an annular first outer raceway surface 2c and an annular second outer raceway surface 2d on an inner peripheral surface thereof. The first outer raceway surface 2c, which is one of the outer raceway rings in a plurality of rows, is located on the back surface side of the outer ring 2. The second outer raceway surface 2d, which is the other outer raceway ring out of the outer raceway rings in the plural rows, is located on the outer surface side of the outer ring 2. The first outer raceway surface 2c and the second outer raceway surface 2d are located at positions where the axes are coincident (the same) and are parallel to each other in the circumferential direction. The pitch circle diameter of the first outer raceway surface 2c and the pitch circle diameter of the second outer raceway surface 2d are equal in size. The pitch circle diameter of the first outer raceway surface 2c and the pitch circle diameter of the second outer raceway surface 2d may be different in size. The first outer raceway surface 2c and the second outer raceway surface 2d have hardened layers whose surface hardness is in the range of 58 to 64HRC by induction hardening. The outer ring 2 has a vehicle body attachment flange 2e on an outer peripheral surface thereof for attachment to a knuckle of a suspension device, not shown. The vehicle body attachment flange 2e has a cylindrical guide (Pilot) portion 2g on the rear surface side thereof, which is fitted to a knuckle of the vehicle.

The hub 3 constituting the inner member is a cylindrical member that rotatably supports a wheel of a vehicle, not shown. The hub 3 is made of medium-high carbon steel containing 0.40 to 0.80wt% of carbon such as S53C. The hub 3 has a small-diameter stepped portion 3a at the back surface side end, and the small-diameter stepped portion 3a is a portion having a small outer diameter in a predetermined range in the axial direction from the back surface side end. That is, the rear surface side end of the small-diameter stepped portion 3a has a caulking portion 3b, which will be described later, extending in the axial direction from the rear surface side end of the hub 3. The hub 3 has a wheel mounting flange 3c for mounting a wheel at an outer side end portion. The wheel mounting flange 3c has hub bolts 3d at circumferentially equally spaced positions. The outer peripheral surface of the hub 3 on the outer surface side (wheel mounting flange 3c side) has a sealing sliding surface 3e having an annular shape in the circumferential direction and a second inner raceway surface 3f having an annular shape which is one of the inner raceway surfaces of the plural rows. The hub 3 is disposed such that the second inner raceway surface 3f faces the second outer raceway surface 2d of the outer ring 2.

The hub 3 is subjected to a hardening treatment from the small diameter stepped portion 3a on the inner surface side to the second inner raceway surface 3f on the outer surface side by high frequency hardening (induction hardening) so that the surface hardness is in the range of 58 to 64 HRC. Thus, the hub 3 has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange 3c, and durability is improved. The hub 3 has a swaged portion 3b in which an inner ring 4 is fitted to the small-diameter stepped portion 3a and a back-surface end portion is plastically deformed radially outward to fix the inner ring 4.

The inner ring 4 is a member that applies a preload to a rear side ball row 5 disposed on the vehicle body side when mounted on the vehicle and an outer side ball row 6 disposed on the wheel side when mounted on the vehicle, which are rolling rows. The inner race 4 has a first inner raceway surface 4a on an outer peripheral surface. The inner ring 4 is fixed to the small-diameter step portion 3a of the hub 3 by press-fitting and caulking. That is, the inner ring 4 forms a first inner raceway surface 4a on the inner side of the hub 3. The first inner raceway surface 4a of the inner ring 4 faces the first outer raceway surface 2c on the back surface side of the outer ring 2. The inner ring 4 applies a preload to the inner-side ball row 5 and the outer-side ball row 6 in accordance with the fixed position in the axial direction with respect to the hub 3.

The rear ball row 5 and the outer ball row 6, which are rolling rows, hold a plurality of balls 9, which are rolling elements, in a ring shape by a retainer. The inner ball row 5 is rollably accommodated between the first inner raceway surface 4a of the inner ring 4 and the first outer raceway surface 2c on the inner surface side of the outer ring 2. The outer-side ball row 6 is rollably accommodated between the second inner raceway surface 3f of the hub 3 and the second outer raceway surface 2d on the outer surface side of the outer ring 2.

The wheel bearing device 1 is constituted by a double row angular contact ball bearing constituted by an outer ring 2, a hub 3, an inner ring 4, a back side row of balls 5, and an outer side row of balls 6. In the present embodiment, the wheel bearing apparatus 1 is not limited to the double row angular contact ball bearing, and may be configured by a double row tapered roller bearing.

The back side seal member 7 as a sealing member is a packing seal (Pack seal) for closing a gap between the outer ring 2 and the inner ring 4. The back side sealing member 7 is constituted by, for example, a 2-side lip type packing material in which 2 seal lips (seal lips) are brought into contact with each other. The back surface side seal member 7 includes a substantially cylindrical seal plate and a substantially cylindrical slinger. The seal plate of the back surface side seal member 7 is fitted to the back surface side opening 2a of the outer ring 2. The cylindrical portion of the slinger of the rear surface side seal member 7 is fitted to the inner ring 4. The back side seal member 7 is configured such that one seal lip of the seal plate is in contact with the slinger via an oil film and is slidable relative to the slinger. Thus, the back surface side seal member 7 can prevent the leakage of the lubricating oil from between the back surface side opening portion 2a of the outer ring 2 and the inner ring 4, and can prevent the intrusion of rainwater, dust, and the like from the outside.

The outer surface side seal member 8 as a sealing member is a seal member that mainly closes a gap between the outer ring 2 and the hub 3. The outer surface side seal member 8 is configured such that a cylindrical portion is fitted in the outer surface side opening 2b of the outer ring 2, and a plurality of seal lips contact or come close to the seal sliding surface 3e of the hub 3 via an oil film, thereby preventing entry of muddy water, foreign matter, or the like from between the outer ring 2 and the hub 3.

The wheel bearing apparatus 1 configured as described above is a double row angular ball bearing including the outer ring 2, the hub 3, the inner ring 4, the inner ball row 5, and the outer ball row 6. The hub 3 is rotatably supported by the outer ring 2 via the inner-side ball row 5 and the outer-side ball row 6. In the wheel bearing device 1, the gap between the outer ring 2 and the inner ring 4 is closed by the back surface side seal member 7, and the gap between the outer ring 2 and the hub 3 is closed by the outer surface side seal member 8. Thus, the wheel bearing device 1 can prevent leakage of lubricating oil from inside and intrusion of rainwater, dust, and the like from outside, and can rotatably support the hub 3 supported by the outer ring 2.

Next, the stiffness value (Nm/deg) of the wheel bearing apparatus 1 to which a preload is applied will be described with reference to fig. 3 to 6. Fig. 3 is a sectional view showing a structure for applying a moment load to the hub 3 of the wheel support bearing device 1. Fig. 4 is a table showing the number of balls 9 as rolling elements that receive a load when a moment load M of 0.1kNm and a moment load M of 0.2kNm are applied to the wheel bearing device 1 for each preload. Fig. 5 is a graph showing a relationship between the moment load M of the wheel support bearing assembly 1 to which a low preload is applied and the inclination angle of the hub 3. Fig. 6 is a graph showing a relationship between the moment load M of the wheel support bearing assembly 1 to which a high preload is applied and the inclination angle of the hub 3. In the present embodiment, the wheel bearing apparatus 1 includes 16 balls 9 in the rear ball row 5 and the outer ball row 6, respectively, and 32 balls in total.

As shown in fig. 3, the rigidity value of the wheel bearing apparatus 1 is measured in a state where the vehicle body attachment flange 2e of the outer ring 2 is fixed to the base B and the offset arm (offset arm) a is fixed to the wheel attachment flange 3c. The wheel bearing apparatus 1 measures the inclination of the axis or the wheel mounting flange 3c generated by applying the force F1 or F2 to the position spaced from the axis of the hub 3 by the offset amount L. The rigidity value of the wheel bearing apparatus 1 is calculated from the moment loads M1 and M2 included in the moment load M, and the inclination angle of the wheel mounting flange 3c of the hub 3 or the inclination angle of the axis of the hub 3 when the moment loads M1 and M2 are applied.

The inclination of the axis of the hub 3 depends on the interval between the rear side row of balls 5 and the outer side row of balls 6, the amount of preload applied to the rear side row of balls 5 and the outer side row of balls 6, the number of balls 9 receiving the moment load M applied to the hub 3, and the like. The greater the preload value, the less the hub 3 is prone to tilting. In addition, the greater the number of balls 9 that receive the moment load M, the less likely the hub 3 will tilt. Therefore, the greater the preload value, the greater the rigidity value of the wheel bearing apparatus 1 becomes. Further, the greater the number of balls 9 receiving the moment load M, the greater the rigidity value of the wheel bearing apparatus 1 becomes. On the other hand, when the number of the balls 9 receiving the moment load M applied to the hub 3 is constant at an arbitrary preload value, the rigidity value of the wheel bearing apparatus 1 is substantially constant (substantially constant) without depending on the fluctuation of the moment load M.

As shown in fig. 4, the wheel bearing apparatus 1, which applies a moment load M of 0.1kNm to the hub 3, receives a load on all the balls 9 of the 32 balls 9 in a range of a preload value of 1.8kN to 4.0 kN. On the other hand, in the wheel bearing device 1 in which the moment load M of 0.2kNm is applied to the hub 3, the number of the balls 9 receiving the moment load M among the 32 balls 9 is changed in the range of the preload value of 1.8kN to 3.0 kN. That is, the wheel support bearing assembly 1 has an inflection point P (see fig. 5) that is a value of the moment load M in which the stiffness value changes when the moment load M of 0.2kNm or less is applied to the hub 3 within the range of the preload value of 1.8kN to 3.0 kN.

As shown in fig. 5, in the wheel bearing device 1 to which a preload of 1.8kN is applied as a low preload, when the moment load M applied to the hub 3 is changed to 1.6kNm, if the moment load M exceeds 0.2kNm, the rate of change of the inclination angle of the axis of the hub 3 with respect to the moment load M increases. That is, in the wheel bearing apparatus 1 having the preload value of 1.8kN, the stiffness value changes before and after the inflection point P with 0.2kNm applied to the hub 3 as the inflection point P of the moment load.

As shown in fig. 6, in the wheel support bearing device 1 to which the preload of 5.2kN is applied as the high preload value, when the moment load M applied to the hub 3 is changed to 1.6kNm, the rate of change of the inclination angle of the axis of the hub 3 with respect to the moment load M is sufficiently smaller than the rate of change of the wheel support bearing device 1 to which the preload of 1.8kN is applied until the moment load M reaches 1.6 kNm. That is, in the wheel bearing apparatus 1 having the preload value of 5.2kN, there is no clear inflection point of the stiffness value in the range of the low moment load having the moment load M of 0.2kNm or less.

As shown in fig. 4, in the wheel bearing device 1 to which the preload of 3.2kN or more is applied, when the low moment load M having the moment load M of ± 0.2kNm as the central value is applied to the hub 3, the state is maintained in which all the balls 9 included in the inner side ball row 5 and the outer side ball row 6 are in contact with the first outer raceway surface 2c and the first inner raceway surface 4a and in contact with the second outer raceway surface 2d and the second inner raceway surface 3f. Of course, even when a moment load M smaller than ± 0.2kNm is applied to the hub 3, the wheel bearing device 1 maintains the state in which all of the balls 9 included in the inner-side ball row 5 and the outer-side ball row 6 are in contact with the first outer raceway surface 2c and the first inner raceway surface 4a and are in contact with the second outer raceway surface 2d and the second inner raceway surface 3f. Therefore, the rigidity value of the wheel bearing apparatus 1 is maintained within a certain range in a low moment load range centered on a moment load M of ± 0.2 kNm. This makes it possible to suppress fluctuations in the rigidity value under a low moment load and improve the steering safety of the vehicle during low-speed straight running or low-speed cornering.

In this case, in the wheel bearing device 1, the lowest preload necessary to bring all the balls 9 included in the inner ball row 5 and the outer ball row 6 into contact with the first outer raceway surface 2c and the first inner raceway surface 4a and into contact with the second outer raceway surface 2d and the second inner raceway surface 3f when the moment load M of ± 0.2kNm is applied to the hub 3 with respect to the outer ring 2 (that is, when the moment load M of ± 0.2kNm is applied to the hub 3 with respect to the outer ring 2) is taken as the preload lower limit value. Therefore, the wheel support bearing device 1 can be set to a preload value that maintains the rigidity value within a predetermined range within a range of a low moment load centered on a moment load M of ± 0.2 kNm. This makes it possible to suppress fluctuations in the rigidity value under a low moment load and improve the steering safety of the vehicle during low-speed straight running or low-speed cornering running.

In the wheel bearing device 1 to which the preload of 3.2kN or more is applied, when the high moment load M of at least ± 1.6kNm is applied to the hub 3, the moment load M is received by all the balls 9 until some of the balls 9 are separated from the first outer raceway surface 2c and the first inner raceway surface 4a or the second outer raceway surface 2d and the second inner raceway surface 3f. Therefore, the wheel support bearing device 1 can maintain the rigidity value within a certain range up to the range of a high moment load of ± 1.6 kNm. This suppresses variation in the rigidity value in the range from the low moment load to the high moment load, and improves the steering safety of the vehicle during straight running or turning running in a wide speed range.

A vehicle having a wheel bearing device receives a wide range of moment loads from a steering wheel to the wheel bearing device according to a road surface condition and a traveling condition of the vehicle. However, in a vehicle in which the steered wheels are supported by the wheel bearing device 1 having the above-described characteristics, even if the moment load input from the steered wheels to the wheel bearing device 1 varies in a range from a low moment load to a high moment load, it is possible to suppress variation in the rigidity value of the wheel bearing device 1. Therefore, the vehicle can improve the steering safety of the vehicle during straight running or turning running in a wide speed range by using the wheel bearing device 1.

The wheel bearing device 1 of the present invention has a third generation structure in which a hub 3 having one inner ring 4 as an inner member is fitted, and the inner ring is rotated by an outer ring 2 as an outer member and a fitting body of the inner ring 4 and the hub 3 as inner members. However, the first generation structure may be a first generation structure including an outer ring as an outer member and a pair of inner rings as an inner member, and the second generation structure may be a second generation structure including an outer ring as an outer member and a pair of inner rings as an inner member, and an inner ring in which the pair of inner rings are fitted to the outer periphery of the hub.

The wheel bearing apparatus 1 according to the present invention has been described as a wheel bearing apparatus for a driven wheel, but may be a wheel bearing apparatus for a driving wheel. The wheel bearing device 1 of the present invention has been described as a wheel bearing device for a steerable wheel, but may be a wheel bearing device for a fixed wheel. The wheel bearing device 1 of the present invention is a wheel bearing device for inner ring rotation in which a hub 3 having a wheel mounting flange 3c and an inner ring 4 rotate. However, the wheel support bearing device may be a wheel support bearing device for rotating an outer ring that rotates with an outer ring having a wheel attachment flange.

While the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, but the above-described embodiments are merely examples, and it is needless to say that the present invention can be further implemented in various forms within a range not departing from the gist of the present invention.

Claims

1. A bearing device for a wheel, comprising:

an outer member having a plurality of annular outer raceway surfaces on an inner peripheral surface thereof, the outer raceway surfaces having a plurality of outer raceway surfaces aligned with each other in an axial direction;

an inner member having a plurality of inner raceway surfaces formed on an outer circumferential surface thereof, the inner raceway surfaces being opposed to the plurality of outer raceway surfaces; and

a plurality of rows of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member,

when a moment load of ± 0.2kNm is applied to the inner member with respect to the outer member, all of the multiple rows of rolling elements are in contact with the raceway surfaces.

2. The wheel bearing apparatus according to claim 1, wherein:

a preload that is a minimum preload required to bring all of the multiple rows of rolling elements into contact with the raceway surfaces when a moment load of ± 0.2kNm is applied to the inner member with respect to the outer member is set as a preload lower limit value.