JP2023043695A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device which has a fiber flow of which an angle to a raceway surface is a predetermined value or less even if intervals between plural rows of raceway rings.SOLUTION: A wheel bearing device 1 is equipped with an outer ring 2 that has plural row of outside raceway surfaces on an inner peripheral surface, and plural rows of balls that are formed with plural rows of inside raceway surfaces opposite to the plural row of outside raceway surfaces on outer peripheral surface, and are stored between both raceway surfaces of the outer ring 2 and a hub ring 3 or an inner ring 4. With respect to the outer ring 2, when a moment load M of ±0.2 kNm is added to the hub ring 3, all of the plural row of balls contact with both raceway surfaces.SELECTED DRAWING: Figure 4

Description

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

A wheel bearing device that rotatably supports a wheel is known. In the wheel bearing device, a hub wheel, which is an inner member connected to a wheel, is rotatably supported by an outer ring, which is an outer member, via rolling elements. In the wheel bearing device, a preload is applied to the rolling elements that rotatably support the hub wheel in order to ensure rigidity above a certain level. By applying a preload to the vehicle bearing device, it is possible to suppress the amount of inclination of the inner ring with respect to the outer ring caused by a moment load.

The wheel bearing device secures rigidity by applying preload so that the rigidity value (Nm/deg), which is the ratio of inclination of the hub wheel to the outer ring when a predetermined moment load is applied to the hub wheel, is within a predetermined value. are doing. However, the wheel bearing device supports the hub wheel with a plurality of rolling elements. Therefore, the wheel bearing device does not have a constant stiffness value under a constant preload. In particular, the rigidity value of the low preload wheel bearing device fluctuates even with moment loads during low-speed straight running and cornering. That is, the stiffness value of the low preload wheel bearing assembly changes at relatively small moment loads. Such a vehicle bearing device with a low preload has an inflection point, which is a moment load value at which the rigidity value changes, which may affect the steering stability of the vehicle during low-speed running. Therefore, there has been proposed a wheel bearing device that suppresses the influence of the fluctuation of the rigidity value of the wheel bearing device on the steering stability of the vehicle. For example, it is as described in Patent Document 1.

A wheel bearing device described in Patent Document 1 has a pressing member between a shaft portion of a constant velocity joint of a vehicle and a hub wheel. The pressing member is a member capable of pressing the hub wheel in the axial direction. The pressing force of the pressing member is controlled by the control unit. The control unit identifies the pressing force from the moment load according to the running 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 wheel with the specified pressing force to correct the inclination of the hub wheel. As a result, the wheel bearing device described in Patent Document 1 can maintain the rigidity value at a constant value.

JP 2017-114375 A

The wheel bearing device described in Patent Literature 1 maintains the rigidity value at a constant value by correcting the inclination of the hub wheel with respect to the moment load with a pressing member. However, in the wheel bearing device, the characteristics of the plurality of rolling elements rotatably supporting the hub wheel against the moment load do not change. In other words, the wheel bearing device described in Patent Document 1 apparently maintains a constant rigidity value with respect to the vehicle by means of the pressing member. Therefore, in the low preload wheel bearing device, fluctuations in the rigidity of the hub wheel relative to the outer wheel may affect the steering stability of the vehicle during low-speed straight running or low-speed cornering.

The present invention has been made in view of the above circumstances, and is a wheel capable of suppressing fluctuations in rigidity under low moment loads and improving the steering stability of a vehicle during low-speed straight running or low-speed turning. It is an object of the present invention to provide a bearing device for a vehicle and a vehicle having the bearing device for a wheel.

That is, the first invention comprises an outer member having an annular double-row outer raceway surface with the axis aligned with the inner peripheral surface, and a double-row outer raceway surface facing the double-row outer raceway surface on the outer peripheral surface. A wheel bearing device comprising: an inner member having an inner raceway surface formed thereon; and a double-row rolling element rollably accommodated between the raceway surfaces of the outer member and the inner member. be. When a moment load of ±0.2 kNm is applied to the inner member with respect to the outer member, all of the double-row rolling elements are in contact with both raceway surfaces.

That is, in the second invention, when a moment load of ±0.2 kNm is applied to the inner member with respect to the outer member, all of the double-row rolling elements are in contact with both raceway surfaces. The minimum preload required for

That is, the third invention is a vehicle having the wheel bearing device according to the first invention and the second invention.

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

As effects of the present invention, the following effects are obtained.

That is, in the first invention, the wheel bearing device contacts the outer raceway surface and the inner raceway surface when a moment load of ±0.2 kNm, which is a low moment load, is applied to the hub wheel. Since a preload is applied to all the rolling elements that are present, all the double-row rolling elements maintain a state of contact with the outer raceway surface and the inner raceway surface. As a matter of course, even when a moment load of less than 0.2 kNm is applied to the hub wheel, the wheel bearing device is in a state in which all of the double-row rolling elements are in contact with the outer raceway surface and the inner raceway surface. is maintained. Therefore, in the wheel bearing device, the stiffness value is maintained within a constant range within a low moment load range centered on the moment load of ±0.2 kNm. As a result, it is possible to suppress fluctuations in the stiffness value under a low moment load, and improve the steering stability of the vehicle during low-speed straight running or low-speed cornering.

In the second invention, in the wheel bearing device, when a moment load of ±0.2 kNm, which is a low moment load, is applied to the hub wheel, all of the double row rolling elements contact both the raceway surfaces. A preload is applied to the rolling elements, with the minimum preload required to hold the rolling element as the preload lower limit. Therefore, the wheel bearing device can appropriately set a preload value that maintains a constant stiffness value within a low moment load range centering on a moment load of ±0.2 kNm. As a result, it is possible to suppress fluctuations in the stiffness value under a low moment load, and improve the steering stability of the vehicle during low-speed straight running or low-speed cornering.

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

[Rigidity value]
In this specification, the stiffness value (Nm/deg) means a moment load required to incline the hub wheel by a unit angle with respect to the outer ring in the wheel bearing device. Alternatively, the stiffness value means the ratio between the moment load applied to the hub wheel and the inclination of the hub wheel with respect to the outer ring when the moment load is applied.

[Low-speed straight running or low-speed turning]
In this specification, low-speed straight travel or low-speed turning travel means a running state in which the vehicle travels straight or turns at a speed of about 20 km/h.

[Low moment load]
In this specification, the low moment load means the moment load applied to the wheel bearing device when the vehicle runs straight or turns at low speed. A low moment load is, for example, a moment load with a central value of ±0.2 kNm.

FIG. 1 is a perspective view showing the overall configuration of a wheel bearing device according to one embodiment of the present invention. FIG. 2 is a cross-sectional view showing the overall configuration of a wheel bearing device according to one embodiment of the present invention. FIG. 3 is a cross-sectional view showing a configuration for applying a moment load to a hub wheel of a wheel bearing device according to an embodiment of the present invention. FIG. 4 is a table showing the number of rolling elements receiving a load for each preload when a moment load of 0.1 kNm and a moment load of 0.2 kNm are respectively applied to the wheel bearing device. FIG. 5 is a graph showing the relationship between the moment load and the inclination angle of the hub wheel in a wheel bearing device to which a specific low preload is applied. FIG. 6 is a graph showing the relationship between the moment load and the inclination angle of the hub wheel in a wheel bearing device to which a specific high preload is applied.

A wheel bearing device 1, which is an embodiment of a wheel bearing device according to the present invention, will be described below with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective view showing the overall configuration of a wheel bearing device 1. As shown in FIG. FIG. 2 is a sectional view showing the overall configuration of the wheel bearing device 1. As shown in FIG.

As shown in FIG. 1, a wheel bearing device 1 rotatably supports a wheel in a suspension system of a vehicle such as an automobile. In this embodiment, the wheel bearing device 1 is a wheel bearing device for a driven wheel. Further, the wheel bearing device 1 is a wheel bearing device for steering wheels that supports steering wheels of a vehicle (not shown).

A wheel bearing device 1 includes an outer ring 2 as an outer member, a hub wheel 3 and an inner ring 4 as inner members, two inner ball trains 5 as rolling trains, an outer ball train 6, and an inner seal. A member 7 and an outer side sealing member 8 are provided. Here, the inner side indicates the vehicle body side of the wheel bearing device 1 when attached to the vehicle body, and the outer side indicates the wheel side of the wheel bearing device 1 when attached to the vehicle body. Moreover, the axial direction represents the 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, is a member that supports the inner members (the hub wheel 3 and the inner ring 4). The outer ring 2 is made of medium-high carbon steel containing 0.40 to 0.80 wt % of carbon, such as S53C, which is formed into a substantially cylindrical shape. The outer ring 2 has an inner side opening 2a into which the inner side seal member 7 is fitted at the inner side end. The outer ring 2 has an outer side opening 2b into which the outer side seal member 8 is fitted at the outer side end.

The outer ring 2 has an annular first outer raceway surface 2c and a second outer raceway surface 2d on its inner peripheral surface. A first outer raceway surface 2c, which is one of the double-row outer raceways, is located on the inner side of the outer race 2. As shown in FIG. A second outer raceway surface 2d, which is the other outer raceway ring of the double-row outer raceway rings, is positioned on the outer side of the outer ring 2. As shown in FIG. In addition, the first outer raceway surface 2c and the second outer raceway surface 2d are positioned such that their axes coincide and are parallel to each other in the circumferential direction. The pitch diameter of the first outer raceway surface 2c and the pitch 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 configured to have different sizes. The first outer raceway surface 2c and the second outer raceway surface 2d have hardened layers with surface hardness in the range of 58 to 64 HRC by induction hardening. The outer ring 2 has a vehicle body attachment flange 2e2e for attachment to a knuckle of a suspension system (not shown) on its outer peripheral surface. The inner side of the vehicle body attachment flange 2e has a cylindrical pilot portion 2g that is fitted to the knuckle of the vehicle.

A hub wheel 3 constituting an inner member is a cylindrical member that rotatably supports a wheel of a vehicle (not shown). The hub wheel 3 is made of medium-high carbon steel containing 0.40 to 0.80 wt% of carbon, such as S53C. The hub wheel 3 has a small-diameter stepped portion 3a, which is a portion whose outer diameter is smaller by a predetermined range in the axial direction from the inner side end, at the inner side end. That is, the inner side end of the small-diameter stepped portion 3a extends axially from the inner side end of the hub wheel 3 and has a crimped portion 3b, which will be described later. The hub wheel 3 has a wheel mounting flange 3c for mounting a wheel on the outer end. The wheel mounting flange 3c has hub bolts 3d at equidistant positions on the circumference. The hub wheel 3 has an annular seal sliding surface 3e in the circumferential direction on the outer peripheral surface on the outer side (wheel mounting flange 3c side) and a second annular inner raceway surface 3f, which is one of the double-row inner raceway surfaces. are doing. The hub wheel 3 is arranged such that the second inner raceway surface 3f and the second outer raceway surface 2d of the outer ring 2 face each other.

The hub wheel 3 is hardened to a surface hardness in the range of 58 to 64 HRC by induction hardening from the small diameter stepped portion 3a on the inner side to the second inner raceway surface 3f on the outer side. As a result, the hub wheel 3 has sufficient mechanical strength against the rotational bending load applied to the wheel mounting flange 3c, and the durability is improved. The hub wheel 3 has an inner ring 4 fitted to the small-diameter stepped portion 3a, and has a crimped portion 3b plastically deformed radially outward at the inner side end to fix the inner ring 4 therein.

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

In the inner ball row 5 and the outer ball row 6, which are rolling rows, a plurality of balls 9, which are rolling elements, are held annularly by retainers. The inner ball row 5 is housed between the first inner raceway surface 4a of the inner ring 4 and the first outer raceway surface 2c of the outer ring 2 on the inner side so as to be able to roll. The outer-side ball train 6 is housed between the second inner raceway surface 3f of the hub wheel 3 and the outer-side second outer raceway surface 2d of the outer ring 2 so as to be able to roll.

A wheel bearing device 1 is composed of a double row angular contact ball bearing including an outer ring 2 , a hub ring 3 and an inner ring 4 , an inner ball train 5 and an outer ball train 6 . In this embodiment, the wheel bearing device 1 is not limited to the double-row angular contact ball bearing, and may be a double-row tapered roller bearing.

The inner side seal member 7, which is a sealing member, is a pack seal that closes the gap between the outer ring 2 and the inner ring 4. As shown in FIG. The inner-side seal member 7 is composed of, for example, a two-side lip type pack seal in which two seal lips are brought into contact with each other. The inner side seal member 7 includes a substantially cylindrical seal plate and a substantially cylindrical slinger. A seal plate of the inner side seal member 7 is fitted into the inner side opening 2 a of the outer ring 2 . A cylindrical portion of the slinger of the inner side seal member 7 is fitted to the inner ring 4 . The inner side seal member 7 is configured to be slidable with respect to the slinger when one side seal lip of the seal plate comes into contact with the slinger via an oil film. As a result, the inner side seal member 7 prevents grease from leaking from between the inner side opening 2a of the outer ring 2 and the inner ring 4, and rainwater and dust from entering from the outside.

The outer-side sealing member 8, which is a sealing member, is a sealing member that mainly closes the gap between the outer ring 2 and the hub wheel 3. As shown in FIG. The outer side seal member 8 has a cylindrical portion fitted in the outer side opening 2b of the outer ring 2, and a plurality of seal lips contact or approach the seal sliding surface 3e of the hub wheel 3 via an oil film. and the hub wheel 3 from entering muddy water or foreign matter.

In the wheel bearing device 1 thus constructed, the outer ring 2, the hub wheel 3, the inner ring 4, the inner ball train 5, and the outer ball train 6 constitute a double-row angular contact ball bearing. The hub wheel 3 is rotatably supported by the outer ring 2 via an inner ball row 5 and an outer ball row 6 . In the wheel bearing device 1 , the inner seal member 7 closes the gap between the outer ring 2 and the inner ring 4 , and the outer seal member 8 closes the gap between the outer ring 2 and the hub wheel 3 . Thus, the wheel bearing device 1 rotatably supports the hub wheel 3 supported by the outer ring 2 while preventing grease from leaking from the inside and rainwater and dust from entering from the outside.

Next, the rigidity value (Nm/deg) of the preloaded wheel bearing device 1 will be described with reference to FIGS. 3 to 6. FIG. FIG. 3 is a sectional view showing a configuration for applying a moment load to the hub wheel 3 of the wheel bearing device 1. As shown in FIG. FIG. 4 shows the number of balls 9 which are rolling elements receiving a load when a moment load M of 0.1 kNm and a moment load M of 0.2 kNm are respectively applied to the wheel bearing device 1 for each preload. It is a table. FIG. 5 is a graph showing the relationship between the moment load M and the inclination angle of the hub wheel 3 in the wheel bearing device 1 to which a low preload is applied. FIG. 6 is a graph showing the relationship between the moment load M and the inclination angle of the hub wheel 3 in the wheel bearing device 1 to which a high preload is applied. In this embodiment, the wheel bearing device 1 includes 16 balls 9 in each of the inner ball row 5 and the outer ball row 6, for a total of 32 balls 9. As shown in FIG.

As shown in FIG. 3, the rigidity value of the wheel bearing device 1 is measured with the vehicle body mounting flange 2e of the outer ring 2 fixed to the base B and the offset arm A fixed to the wheel mounting flange 3c. In the wheel bearing device 1, the tilt angle of the axis or the wheel mounting flange 3c generated by applying a force F1 or F2 to the position of the offset amount L from the axis of the hub wheel 3 is measured. The rigidity value of the wheel bearing device 1 is determined by 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 wheel 3 or the axis of the hub wheel 3 when the moment loads M1 and M2 are applied. calculated from the tilt angle of

The inclination of the axis of the hub wheel 3 depends on the distance between the inner ball train 5 and the outer ball train 6, the preload applied to the inner ball train 5 and the outer ball train 6, and the moment load M applied to the hub wheel 3. It is determined by the number of balls 9 being received and the like. The larger the preload value, the less likely the hub wheel 3 will tilt. Further, the larger the number of balls 9 receiving the moment load M, the less likely the hub wheel 3 will tilt. Therefore, the rigidity value of the wheel bearing device 1 increases as the preload value increases. Further, the rigidity value of the wheel bearing device 1 increases as the number of balls 9 receiving the moment load M increases. On the other hand, when the number of balls 9 receiving the moment load M applied to the hub wheel 3 is constant at any preload value, the rigidity value of the wheel bearing device 1 is substantially constant regardless of fluctuations in the moment load M. .

As shown in FIG. 4, in the wheel bearing device 1 in which a moment load M of 0.1 kNm is applied to the hub wheel 3, all of the 32 balls 9 are ball 9 is loaded. On the other hand, the wheel bearing device 1 in which a moment load M of 0.2 kNm is applied to the hub wheel 3 receives the moment load M among the 32 balls 9 within a preload value range of 1.8 kN to 3.0 kN. The number of balls 9 in position is changing. In other words, when the wheel hub 3 is applied with a moment load M of 0.2 kNm or less in the preload value range of 1.8 kN to 3.0 kN, the wheel bearing device 1 is set to a value of the moment load M at which the rigidity value changes. It has an inflection point P (see FIG. 5).

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

As shown in FIG. 6, in the wheel bearing device 1 in which a preload of 5.2 kN is applied as a high preload value, when the moment load M applied to the hub wheel 3 is varied up to 1.6 kNm, the moment load M is 1.6 kNm. The rate of change of the inclination angle of the axis of the hub wheel 3 with respect to the moment load M until it reaches 6 kNm is sufficiently smaller than the rate of change in the wheel bearing device 1 to which a preload of 1.8 kN is applied. That is, the wheel bearing device 1 having a preload value of 5.2 kN does not have a clear inflection point of the stiffness value in the low moment load range where the moment load M is 0.2 kNm or less.

As shown in FIG. 4, when a low moment load M whose median value is ±0.2 kNm is applied to the hub wheel 3, the wheel bearing device 1 to which a preload of 3.2 kN or more is applied, the inner A state in which all the balls 9 included in the 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 the second outer raceway surface 2d and the second inner raceway surface 3f. is maintained. As a matter of course, in the wheel bearing device 1, even when a moment load M of less than ±0.2 kNm is applied to the hub wheel 3, all the balls 9 included in the inner ball row 5 and the outer ball row 6 are in the first position. The state of contact between the outer raceway surface 2c and the first inner raceway surface 4a and the second outer raceway surface 2d and the second inner raceway surface 3f is maintained. Therefore, the wheel bearing device 1 maintains a constant stiffness value within a low moment load range centered on the moment load M of ±0.2 kNm. As a result, it is possible to suppress fluctuations in the stiffness value under a low moment load, and improve the steering stability of the vehicle during low-speed straight running or low-speed cornering.

At this time, when a moment load M of ±0.2 kNm is applied to the hub wheel 3 with respect to the outer ring 2, the wheel bearing device 1 has all the balls 9 included in the inner ball row 5 and the outer ball row 6. is in contact with the first outer raceway surface 2c and the first inner raceway surface 4a, and the second outer raceway surface 2d and the second inner raceway surface 3f. Therefore, the wheel bearing device 1 can appropriately set a preload value that maintains a constant stiffness value within a low moment load range centered on the moment load M of ±0.2 kNm. As a result, it is possible to suppress fluctuations in the stiffness value under a low moment load, and improve the steering stability of the vehicle during low-speed straight running or low-speed cornering.

Further, in the wheel bearing device 1 to which a preload of 3.2 kN or more is applied, even when a high moment load M of at least ±1.6 kNm is applied to the hub wheel 3, some of the balls 9 do not fall on the first outer raceway surface 2c. All the balls 9 receive the moment load M until they leave the first inner raceway surface 4a or the second outer raceway surface 2d and the second inner raceway surface 3f. Therefore, the wheel bearing device 1 maintains the stiffness value within a constant range up to a high moment load range of ±1.6 kNm. As a result, it is possible to suppress variations in the stiffness value in the range from low moment load to high moment load, and improve the steering stability of the vehicle during straight running or turning in a wide speed range.

In a vehicle having a wheel bearing device, a wide range of moment loads are input from the steered wheels to the wheel bearing device according to road surface conditions and vehicle running conditions. However, in a vehicle in which the steered wheels are supported by the wheel bearing device 1 having the characteristics described above, the moment load input from the steered wheels to the wheel bearing device 1 fluctuates within a range from a low moment load to a high moment load. Even so, the variation in the rigidity value of the wheel bearing device 1 is suppressed. Therefore, the wheel bearing device 1 of the vehicle can improve the steering stability of the vehicle during straight running or turning in a wide speed range.

A wheel bearing device 1 according to the present application includes a hub ring 3 in which an inner ring 4 is fitted as an inner member. It has a 3rd generation structure with inner ring rotation specifications. However, the first generation structure composed of the outer ring as the outer member and the pair of inner rings as the inner member, the outer ring as the outer member and the pair of inner rings as the inner member, and the pair of inner rings may be a second-generation structure with an inner ring rotation specification in which is fitted to the outer periphery of the hub wheel.

Further, although the wheel bearing device 1 in the present application has been described as a wheel bearing device for a driven wheel, it may be a wheel bearing device for a driving wheel. Further, although the wheel bearing device 1 in the present application has been described as a wheel bearing device for a steered wheel, it may be a wheel bearing device for a fixed wheel. Further, the wheel bearing device 1 in the present application is a wheel bearing device for inner ring rotation in which the hub wheel 3 having the wheel mounting flange 3c and the inner ring 4 rotate. However, the wheel bearing device may be an outer ring rotating wheel bearing device in which an outer ring having a wheel mounting flange rotates.

Although the embodiments of the present invention have been described above, the present invention is not limited to such embodiments in any way, and is merely an example. The scope of the present invention is indicated by the description of the claims, and the meaning of equivalents described in the claims and all changes within the scope include.

REFERENCE SIGNS LIST 1 wheel bearing device 2 outer ring 2a inner side opening 2b outer side opening 2c first outer raceway surface 2d second outer raceway surface 2e vehicle mounting flange 2g pilot portion 3 hub wheel 3a small diameter stepped portion 3b crimped portion 3c wheel mounting flange 3d Hub bolt 3e Seal sliding surface 3f Second inner raceway surface 4 Inner ring 4a First inner raceway surface 5 Inner side ball row 6 Outer side ball row 7 Inner side seal member 8 Outer side seal member 9 Ball M Moment load F Force L Distance P inflection point

Claims (2)

an outer member having an annular double-row outer raceway surface whose axis coincides with the inner peripheral surface;
an inner member having a double-row inner raceway surface facing the double-row outer raceway surface formed on an outer peripheral surface;
A wheel bearing device comprising: a double-row rolling element rollably accommodated between the raceway surfaces of the outer member and the inner member,
All of the double-row rolling elements are in contact with both raceway surfaces when a moment load of ±0.2 kNm is applied to the inner member with respect to the outer member,
Wheel bearing device. The wheel bearing device according to claim 1,
A minimum preload required for all of the double-row rolling elements to be in contact with both raceway surfaces when a moment load of ±0.2 kNm is applied to the inner member with respect to the outer member. Preload lower limit value,
Wheel bearing device.

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