JP2020050177A - Wheel bearing device - Google Patents

Abstract

To provide a wheel bearing device in which deterioration in roundness of an outer raceway surface along elastic deformation of a flange mounted on a vehicle due to bolt fastening force is suppressed so as to prevent a reduction in bearing life.SOLUTION: There is provided a wheel bearing device 1 comprising an outer ring 2 having a flange 2e to be attached onto a vehicle body on its outer circumference; an inner member comprising a hub ring 3 and at least one inner ring 4 press-fitted into the hub ring 3; and multiple ball lines 5 and 6 rotatably accommodated between track surfaces of both of the outer ring 2 and the inner member. The flange 2e to be attached onto a vehicle body has a pitch circle P which is centered on the center axis of the outer ring 2 and provided with at least four bolt holes 2g. Four bolt holes 2g among the bolt holes 2g which are adjacent one another on the pitch circle P with interposed a reference line B orthogonal to the center axis are of phase angles θ1, θ2, θ3, and θ4 for the bolt holes 2g within a predetermined range. The four bolt holes are arranged in a manner where a straight line orthogonal to the center axis and the reference line B is a symmetry axis S..SELECTED DRAWING: Figure 2

Description

  The present invention relates to a bearing device for a wheel.

  2. Description of the Related Art Conventionally, a wheel bearing device that rotatably supports wheels in a suspension device of an automobile or the like has been known. For example, in a wheel bearing device, a hub wheel, which is an inner member connected to a wheel, is rotatably supported by an outer member via a rolling element. In the bearing device for a wheel, an outer member is fixed to a knuckle constituting a suspension device by a vehicle body mounting flange. In other words, the wheel bearing device rotatably supports the wheel connected to the inner member while being fixed to the knuckle.

  In such a wheel bearing device, when the vehicle body mounting flange is fixed to the knuckle with bolts, the mounting flange is elastically deformed according to the mounting surface of the knuckle, and the raceway surface of the rolling element formed on the outer member is formed. The roundness was sometimes deteriorated. It is known that the bearing life for a wheel decreases as the roundness of the raceway surface deteriorates. Therefore, there is known a wheel bearing device that suppresses deterioration of roundness of a raceway surface and prevents a reduction in bearing life. For example, as described in Patent Document 1.

JP-A-2017-128236

  The wheel bearing device described in Patent Literature 1 is formed such that the thickness of the vehicle body mounting flange of the outer member is larger than the thickness of the knuckle mounting portion. With such a configuration, the mounting flange is less likely to be elastically deformed following the mounting surface of the knuckle, and deterioration of the roundness of the raceway surface is suppressed. However, in the bearing device for a wheel, the mounting flange is elastically deformed by the fastening force of a bolt for fixing the vehicle body mounting flange to the knuckle. For this reason, depending on the arrangement of the bolts on the vehicle body mounting flange, the vehicle body mounting flange may be elastically deformed to such an extent that the roundness of the raceway surface is deteriorated.

  The present invention has been made in view of the above circumstances, and suppresses the deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt, thereby preventing a reduction in bearing life. It is an object of the present invention to provide a bearing device for a wheel that can perform the following.

  That is, the first invention is a hub wheel having a vehicle body mounting flange on the outer periphery, an outer member having a double row of outer raceway surfaces formed on the inner periphery, and a small diameter step portion extending in the axial direction on the outer periphery. And at least one inner ring press-fitted into the small-diameter step portion of the hub wheel, and a double-row inner raceway surface facing the double-row outer raceway surface on an outer peripheral surface of the hub wheel and the inner ring. A wheel bearing device comprising: a formed inner member; and a plurality of rows of rolling elements rotatably accommodated between both raceway surfaces of the outer member and the inner member. The mounting flange has at least four bolt holes on a pitch circle centered on the center axis of the outer member, and the bolt holes have a reference line orthogonal to the center axis on the pitch circle. The four bolt holes adjacent at the center of the pitch circle with respect to the reference line A phase angle of the bolt hole, which is an acute angle formed by a straight line passing through the center of each of the bolt holes, is within a predetermined range, and a straight line orthogonal to the center axis and the reference line is arranged as a symmetric axis. Wheel bearing device.

  The second invention is a bearing device for a wheel, wherein a phase angle of the bolt hole is arbitrarily set within a predetermined range of 37 ° to 45 °.

  A third invention is a bearing device for a wheel, wherein portions between the bolt holes adjacent to each other across the reference line are connected to each other in the vehicle body mounting flange.

  According to a fourth aspect of the present invention, a band-shaped portion is formed on the outer peripheral surface of the outer member on the outer side at a predetermined width and protrudes by a predetermined amount in a radial direction, and at least a part overlaps with the outer raceway surface in a radial direction. Wheel bearing device.

  A fifth invention is a bearing device for a wheel, wherein at least a part of the vehicle body mounting flange overlaps the outer raceway surface on the outer side or the inner side in a radial direction.

  The present invention has the following effects.

  That is, in the first invention, four bolt holes are formed in a predetermined range from the reference line in a state of being regularly dispersed. As a result, deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt can be suppressed, and a reduction in bearing life can be prevented.

  In the second invention, the range of the bolt hole phase angle is set so that the ratio of the life reduction to the bearing life in the arrangement of the bolt holes where the elastic deformation of the vehicle body mounting flange is minimized falls within a predetermined range. As a result, deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt can be suppressed, and a reduction in bearing life can be prevented.

  According to the third aspect, the rigidity between the adjacent bolt holes in the vehicle body mounting flange is improved, so that the vehicle body mounting flange is less likely to be elastically deformed. As a result, deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt can be suppressed, and a reduction in bearing life can be prevented.

  According to the fourth aspect of the present invention, since the outer raceway surface on the outer side is formed, a portion having a reduced thickness is supplemented by the belt-shaped portion, so that the rigidity of the outer member is improved. As a result, deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt can be suppressed, and a reduction in bearing life can be prevented.

  According to the fifth aspect of the invention, at least a part of the part whose thickness is reduced by forming the outer raceway surface is covered by the vehicle body mounting flange, so that the rigidity of the outer member is improved. As a result, deterioration of the roundness of the outer raceway surface due to the elastic deformation of the vehicle body mounting flange due to the fastening force of the bolt can be suppressed, and a reduction in bearing life can be prevented.

Sectional drawing which shows the whole structure of the bearing device for wheels. FIG. 2 is a view of the vehicle body mounting flange according to the first embodiment of the wheel bearing device, as viewed in the direction of arrow A in FIG. 1. The figure which shows the graph showing the relationship between the phase angle of the bolt hole in the vehicle body mounting flange, and the roundness of the outer ring raceway surface. The figure which shows the graph showing the relationship between the roundness of the outer ring raceway surface in a bearing device for wheels, and bearing life. The figure which shows the graph showing the relationship between the phase angle of the bolt hole in a vehicle body mounting flange, and a bearing life. FIG. 2 is a view taken in the direction of arrow A in FIG. 1 when the number of bolt holes of a vehicle body mounting flange according to the first embodiment of the wheel bearing device is different. FIG. 2 is a view of a vehicle body mounting flange according to a second embodiment of the wheel bearing device, as viewed in the direction of arrow A in FIG. 1. The A arrow view in FIG. 1 of the vehicle body mounting flange which concerns on 4th Embodiment of the bearing device for wheels.

  The wheel bearing device 1 according to the first embodiment of the wheel bearing device according to the present invention will be described below with reference to FIGS. 1 and 2.

  As shown in FIG. 1, a wheel bearing device 1 rotatably supports wheels in a suspension system of a vehicle such as an automobile. The wheel bearing device 1 includes an outer ring 2, which is an outer member, a hub wheel 3, an inner ring 4, which is an inner member, two inner ball rows 5, an outer ball row 6, which are rolling rows, and an inner seal. A member 9 and an outer seal member 10 are provided. Here, the inner side indicates the vehicle body side of the wheel bearing device 1 when mounted on the vehicle body, and the outer side indicates the wheel side of the wheel bearing device 1 when mounted on the vehicle body. The axial direction represents a direction along the rotation axis of the wheel bearing device 1.

  The outer ring 2 is made of, for example, medium-high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C. At the inner end of the outer race 2, an inner opening 2a into which the inner seal member 9 can be fitted is formed. An outer opening 2b into which the outer seal member 10 can be fitted is formed at the outer end of the outer race 2. The inner peripheral surface of the outer race 2 is formed with an inner-side outer raceway surface 2c and an outer-side outer raceway surface 2d formed in a ring shape. A hardened layer having a surface hardness in the range of 58 to 64 HRC is formed on the inner raceway surface 2c on the inner side and the outer raceway surface 2d on the outer side by, for example, induction hardening. On the outer peripheral surface of the outer ring 2, a vehicle body mounting flange 2e for mounting to a member (knuckle) on the vehicle body side (not shown) is integrally formed. Four bolt holes 2g (see FIG. 3) are formed in the vehicle body mounting flange 2e in the axial direction.

  The hub wheel 3 is made of, for example, medium-high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C. At the inner end of the hub wheel 3, a small-diameter stepped portion 3a whose diameter is smaller than that of the outer end is formed on the outer peripheral surface. At the outer end of the hub wheel 3, a wheel mounting flange 3b for mounting a wheel is integrally formed. A plurality of hub bolts 3e are provided on the wheel mounting flange 3b at circumferentially equidistant positions. Further, the hub wheel 3 is provided with an inner raceway surface 3c on the outer side so as to face the outer raceway surface 2d on the outer side of the outer race 2. The hub wheel 3 has a lip sliding surface 3d of the outer seal member 10 formed on the base side of the wheel mounting flange 3b. An inner ring 4 is provided on the small-diameter step portion 3 a of the hub wheel 3.

  The inner ring 4 is a rolling row and applies preload to an inner-side ball row 5 disposed on the vehicle body side when mounted on a vehicle and an outer-side ball row 6 disposed on the wheel side when mounted on a vehicle. On the outer peripheral surface of the inner ring 4, an annular inner raceway surface 4a is formed in the circumferential direction. The inner ring 4 is fixed to the small-diameter step portion 3a of the hub wheel 3 by press fitting and crimping. That is, on the inner side of the hub wheel 3, the inner raceway 4 forms the inner raceway surface 4a. The inner raceway surface 4a of the inner race 4 faces the inner raceway surface 2c of the outer race 2.

  In the inner side ball row 5 and the outer side ball row 6 which are rolling rows, a plurality of balls 7 which are rolling elements are annularly held by a retainer 8. The inner-side ball row 5 is rotatably sandwiched between the inner raceway surface 4a of the inner race 4 and the inner raceway surface 2c of the outer race 2. The outer-side ball row 6 is rotatably sandwiched between the inner raceway surface 3c of the hub wheel 3 and the outer raceway surface 2d of the outer race 2 on the outer side.

  In the wheel bearing device 1, a double-row angular ball bearing is configured by the outer ring 2, the hub wheel 3 and the inner ring 4, the inner-side ball row 5, and the outer-side ball row 6. In the present embodiment, the inner-side ball row 5 and the outer-side ball row 6 have double-row angular contact ball bearings in the wheel bearing device 1, but have double-row tapered roller bearings. May be.

  The inner-side seal member 9, which is a sealing member, is a pack seal that closes a gap between the inner-side opening 2 a of the outer ring 2 and the inner ring 4. The inner-side seal member 9 is formed of, for example, a two-side lip type pack seal with an encoder that contacts two seal lips. The plurality of seal lips of the inner seal member 9 come into contact with or approach the sliding surface via a grease oil film to prevent the grease inside the wheel bearing device 1 from leaking to the outside. To prevent muddy water and dust from entering the inside from outside. Accordingly, the inner seal member 9 prevents leakage of lubricating grease from the inner opening 2a of the outer race 2 and entry of rainwater, dust, and the like from the outside.

  The outer-side sealing member 10 serving as a sealing member is a sealing member that mainly closes a gap between the outer ring 2 and the hub wheel 3. The outer-side seal member 10 has a cylindrical portion fitted into the outer-side opening 2b of the outer ring 2 and a plurality of seal lips contacting or approaching the lip sliding surface 3d of the hub wheel 3 via an oil film. 3 is slidable.

  As shown in FIG. 2, bolts for fixing the wheel bearing device 1 to the knuckle of the vehicle body are fastened to the four bolt holes 2g of the vehicle body mounting flange 2e. The four bolt holes 2g are formed in a protruding portion 2f of the vehicle body mounting flange 2e that protrudes radially outward of the outer ring 2. The four bolt holes 2 g are arranged on a pitch circle P centered on the center axis of the outer ring 2. In addition, the four bolt holes 2g are arranged with a reference line B intersecting the center axis of the outer ring 2 and passing through the center C of the pitch circle P interposed therebetween. Furthermore, the four bolt holes 2g are arranged so as to be line-symmetric with respect to a straight line passing through the center C of the pitch circle P and being orthogonal to the reference line B and having a symmetry axis S. That is, when the reference line B is the X axis and the symmetry axis S is the Y axis, the vehicle body mounting flange 2e has the projections 2f formed at positions corresponding to the respective quadrants on the XY plane, and the projections 2f. Are formed with bolt holes 2g.

  The acute angle of the angle formed by the straight line passing through the center of the bolt hole 2g and the center C of the pitch circle P in the first quadrant Q1 with the reference line B is set in the first quadrant Q1. The first phase angle θ1 is the phase angle of the bolt hole 2g. Similarly, the phase angle of the bolt hole 2g located in the second quadrant Q2 is the second phase angle θ2, the phase angle of the bolt hole 2g located in the third quadrant Q3 is the third phase angle θ3, and the fourth quadrant. The phase angle of the bolt hole 2g arranged in Q4 is defined as a fourth phase angle θ4. Since the four bolt holes 2g are arranged symmetrically with respect to the Y axis which is the axis of symmetry S, the first phase angle θ1 is equal to the second phase angle θ2, and the third phase angle θ3 is equal to the fourth phase angle θ3. And the phase angle θ4 is equal. In the present embodiment, the four bolt holes 2g are arranged such that both the first phase angle θ1 and the fourth phase angle θ4 are 45 °. That is, the four bolt holes 2g are arranged such that the first phase angle θ1 to the fourth phase angle θ4 are the same angle, that is, 45 °.

  As shown in FIG. 3, the circularity of the outer raceway surface 2c on the inner side of the outer race 2 and the outer raceway surface 2d on the outer side (see FIG. 1) are the same from the first phase angle θ1 to the fourth phase angle θ4. At 45 °, which is the angle of In other words, the outer raceway surfaces 2c and 2d apply the fastening force generated in the bolt holes 2g to the vehicle body mounting flange 2e more uniformly as the difference in the spacing between the bolt holes 2g becomes smaller, so that the elasticity due to the bolt fastening force is increased. Deformation is suppressed. In addition, as shown in FIG. 4, the bearing life of the wheel bearing device 1 decreases as the roundness of the outer raceway surfaces 2c and 2d deteriorates. Therefore, as shown in FIG. 5, the bearing life with respect to the phase angle of the wheel bearing device 1 based on FIGS. 3 and 4 is 45 ° where the first phase angle θ1 to the fourth phase angle θ4 are the same angle. When the first phase angle θ1 to the fourth phase angle θ4 are the same angle of 37 °, the bearing life L1 is about half of the longest bearing life L1.

  The thus configured wheel bearing device 1 is configured such that the first phase angle θ1 to the fourth phase angle θ4 of the four bolt holes 2g are set as a predetermined range between 37 ° and 45 °, thereby providing a reference line. Four bolt holes 2g are arranged in a predetermined range from B in a state of being regularly dispersed. In the wheel bearing device 1, the ratio of the reduction in the bearing life to the longest bearing life L1 falls within the predetermined range by arranging the four bolt holes 2g at the phase angle within the predetermined range. As a result, the wheel bearing device 1 suppresses the deterioration of the roundness of the outer raceway surfaces 2c and 2d (see FIG. 1) due to the elastic deformation of the vehicle body mounting flange 2e due to the fastening force of the bolt, and suppresses a significant bearing life. The drop can be prevented.

  In the present embodiment, the wheel bearing device 1 has four bolt holes 2g formed in the vehicle body mounting flange 2e, but the present invention is not limited to this. Further bolt holes are further provided between the four bolt holes 2g. It may be provided. For example, as shown in FIG. 6, the wheel bearing device 1 is provided between the bolt hole 2g disposed in the first quadrant Q1 of the vehicle body mounting flange 2e and the bolt hole 2g disposed in the second quadrant Q2, and The bolt hole 2g may be further arranged on the Y axis between the bolt hole 2g arranged in the quadrant Q3 and the bolt hole 2g arranged in the fourth quadrant Q4. With this configuration, the six bolt holes 2g are arranged so as to be symmetrical with respect to the Y axis which is the symmetry axis S, and are arranged in a regularly dispersed state on the vehicle body mounting flange 2e.

  Next, a wheel bearing device 1 according to a second embodiment of the wheel bearing device according to the present invention will be described with reference to FIG. The wheel bearing device 1 according to each of the following embodiments is a name used in the description as being applied to the wheel bearing device 1 shown in FIGS. 1 and 2 in place of the wheel bearing device 1. , Drawing numbers and reference numerals are used to refer to the same parts, and in the following embodiments, the same points as those of the already described embodiment will not be specifically described, and different parts will be mainly described. .

  As shown in FIG. 7, a vehicle body mounting flange 2h for mounting to a member (knuckle) on the vehicle body side (not shown) is integrally formed on the outer peripheral surface of the outer race 2. Four bolt holes 2g are formed in the vehicle body mounting flange 2h. The four bolt holes 2g are protruding portions 2f of the vehicle body mounting flange 2h that protrude radially outward of the outer ring 2, and are formed on a pitch circle P centered on the center axis of the outer ring 2. The first phase angle θ1 to the fourth phase angle θ4 are arranged so as to be within a predetermined range of 37 ° with respect to a reference line B passing through the center C of the pitch circle P.

  In the vehicle body mounting flange 2h, the projection 2f of the first quadrant Q1 and the projection 2f of the fourth quadrant Q4 are connected, and the projection 2f of the second quadrant Q2 and the projection 2f of the third quadrant Q3 are connected. I have. That is, the vehicle body mounting flange 2h includes a recessed portion (light black portion) between the projecting portion 2f of the first quadrant Q1 and the projecting portion 2f of the fourth quadrant Q4, and a projecting portion 2f of the second quadrant Q2 and the projecting portion 2f of the third quadrant Q3. The concave portion (light black portion) between the protruding portions 2f is formed in a state where it is built up. The vehicle body mounting flange 2h thus formed has improved rigidity and is less likely to be elastically deformed by connecting the adjacent protruding portions 2f. As a result, the wheel bearing device 1 suppresses the deterioration of the roundness of the outer raceway surfaces 2c and 2d due to the elastic deformation of the vehicle body mounting flange 2h due to the fastening force of the bolt, thereby preventing a reduction in the bearing life. it can.

  Next, a wheel bearing device 1 which is a third embodiment of the wheel bearing device according to the present invention will be described with reference to FIG.

  As shown in FIG. 8, the four bolt holes 2g of the vehicle body mounting flange 2i are arranged so as to be symmetrical with respect to the Y axis which is the symmetry axis S, so that the first phase angle θ1 and the second phase angle θ2 is equal, and the third phase angle θ3 is equal to the fourth phase angle θ4. On the other hand, the four bolt holes 2g are arranged so that the first phase angle θ1 and the fourth phase angle θ4 are different angles. For example, the four bolt holes 2g are arranged such that the first phase angle θ1 and the second phase angle θ2 are at the same angle of 37 °, and the third phase angle θ3 and the fourth phase angle θ4 are the same. Are arranged at an angle of 45 °. Thereby, the length D1 of the bolt holes 2g arranged in the first quadrant Q1 and the second quadrant Q2 from the reference line B is determined by the reference of the bolt holes 2g arranged in the third and fourth quadrants Q3 and Q4. This is approximately 85% of the length D2 from the line B.

  As described above, in the wheel bearing device 1, each of the bolt holes 2 g is disposed symmetrically with respect to the symmetry axis S perpendicular to the reference line B, and the first of the bolt holes 2 g disposed with the reference line B interposed therebetween. The phase angle θ1 and the fourth phase angle θ4 are set to arbitrary different values within a predetermined range. In other words, the wheel bearing device 1 is provided with the bolt holes 2g at positions where the mounting space on the knuckle side is taken into account in a state where the rate of reduction of the bearing life with respect to the longest bearing life L1 is kept within a predetermined range. As a result, the wheel bearing device 1 maintains the degree of freedom in the layout of the bolt holes 2g, while maintaining the degree of circularity of the outer raceway surfaces 2c and 2d due to the elastic deformation of the vehicle body mounting flange 2i due to the fastening force of the bolt. Deterioration is suppressed, and significant reduction in bearing life can be prevented.

  As shown in FIG. 1, in all the embodiments, in the wheel bearing device 1, a belt-shaped portion 2 k may be formed on the outer peripheral surface of the outer ring 2 on the outer side to improve the rigidity of the outer ring 2. The belt-like portion 2k projects a predetermined amount in the radial direction at a predetermined width over the entire circumference. The belt-shaped portion 2k is formed at a position overlapping the outer raceway surface 2d on the outer side when viewed from the radial direction of the outer ring 2. The band 2k is formed to cover the bottom of the outer rolling surface 2d. That is, the belt-shaped portion 2k is formed at a position covering the thinnest portion of the portion where the outer rolling surface 2d is formed.

  In addition, the wheel bearing device 1 may be formed such that the vehicle body mounting flanges 2e, 2h, and 2i in the respective embodiments overlap with the outer raceway surface 2d on the outer side when the outer race 2 is viewed in the radial direction. The vehicle body mounting flanges 2e, 2h, and 2i are formed, for example, so as to cover the bottom of the outer rolling surface 2d. That is, the vehicle body mounting flanges 2e, 2h, and 2i are formed at positions where the outermost raceway 2d on the outer side of the outer race 2 is formed to cover the thinnest part. The vehicle body mounting flanges 2e, 2h, and 2i may be formed at positions overlapping with the outer raceway surface 2c on the inner side in the radial direction of the outer race 2.

  The outer ring 2 formed in this manner has at least a part of the portion reduced in thickness by the outer raceway surfaces 2c and 2d covered by the band-like portion 2k or the vehicle body mounting flanges 2e, 2h, and 2i. The rigidity is improved. As a result, the wheel bearing device 1 further suppresses the deterioration of the roundness of the outer raceway surfaces 2c and 2d due to the elastic deformation of the vehicle body mounting flanges 2e, 2h and 2i due to the fastening force of the bolt, and reduces the life of the bearing. Can be prevented.

  The wheel bearing device 1 in the present application is configured as a wheel bearing device 1 of a third generation structure in which the inner raceway surface 3c is directly formed on the outer periphery of the hub wheel 3, but is not limited thereto. A second generation structure in which a pair of inner rings 4 are press-fitted and fixed to the wheel 3 may be used.

  As described above, the embodiments of the present invention have been described. However, the present invention is not limited to these embodiments at all, but is merely an example, and may be variously modified without departing from the gist of the present invention. It goes without saying that the scope of the present invention is indicated by the description of the claims, and furthermore, the equivalent meaning described in the claims, and all the changes within the scope are described. Including.

DESCRIPTION OF SYMBOLS 1 Wheel bearing device 2 Outer ring 2g Bolt hole 3 Hub ring 4 Inner ring 9 Inner side seal member 10 Outer side seal member B Reference line S Symmetry axis P Pitch circle θ1 First phase angle θ2 Second phase angle θ3 Third phase angle θ4 4th phase angle

Claims (5)

An outer member having a vehicle body mounting flange on an outer periphery, and a double row outer raceway surface formed on an inner periphery,
A hub wheel having a small-diameter stepped portion extending in the axial direction on the outer periphery, and at least one inner ring press-fitted into the small-diameter stepped portion of the hub wheel; An inner member formed with a double row of inner raceways facing the outer raceway of the row,
A double-row rolling element rotatably accommodated between both raceway surfaces of the outer member and the inner member, and a bearing device for a wheel,
The vehicle body mounting flange has at least four bolt holes on a pitch circle centered on the center axis of the outer member,
Of the bolt holes, four bolt holes adjacent on the pitch circle across a reference line orthogonal to the central axis are:
The phase angle of the bolt hole, which is an acute angle formed by the center of the pitch circle and the straight line passing through the center of each bolt hole with respect to the reference line, is within a predetermined range, and the central axis and the reference line A wheel bearing device arranged such that a straight line perpendicular to the axis becomes a symmetric axis.   The wheel bearing device according to claim 1, wherein a phase angle of the bolt hole is in a predetermined range of 37 ° to 45 °.   3. The wheel bearing device according to claim 1, wherein portions of the bolt holes adjacent to each other across the reference line are connected to each other in the vehicle body mounting flange. 4.   A belt-shaped portion is formed on an outer peripheral surface of the outer member on the outer side of the outer member and has a predetermined width and protrudes by a predetermined amount in a radial direction, and at least a part thereof overlaps with the outer raceway surface in a radial view. Item 4. The bearing device for a wheel according to any one of items 3.   The wheel bearing device according to any one of claims 1 to 4, wherein at least a part of the vehicle body mounting flange overlaps the outer raceway surface on the outer side or the inner side when viewed in the radial direction.

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