Wheel bearing device

Abstract

To provide a wheel bearing device which suppresses swing of a wheel mounting flange due to bolt fastening by specifying dimensional relation of each section of the wheel mounting flange.SOLUTION: A vehicle wheel mounting flange 3b of a vehicle wheel bearing device 1 includes: a plurality of screw holes 31 into which wheel bolts that fix a wheel and a brake rotor are screwed; and a rib 35 provided on an inner side circumferential edge of the screw holes 31. When A represents a nominal diameter of the screw hole 31, B represents a width direction dimension of the rib 35 in a cross-section that passes through a center of the screw hole 31 and that is tangent to a pitch circle of the screw hole 31, and C represents a thickness direction dimension of the vehicle wheel mounting flange 3b that passes through the rib 35, B / A≥1.7 and C / A≥0.8 are satisfied.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, a wheel bearing device has been known in which a wheel mounting flange is integrally formed on the outer periphery of a hub wheel, and a plurality of bolt holes are provided in the wheel mounting flange, with hub bolts for attaching a brake rotor and wheel being press-fitted into each bolt hole.

[0003] In such wheel bearing devices, when the hub bolts are press-fitted, the material undergoes plastic flow, causing undulations in the wheel mounting flange and increasing runout of the wheel mounting flange. Deterioration in the runout accuracy of the wheel mounting flange can cause brake judder. To address this issue, for example, a configuration has been proposed in which counterbore portions are provided around the bolt holes on the side of the brake rotor in the wheel mounting flange to absorb plastic flow (see Patent Document 1).

[0004] Another proposed wheel bearing device is one that eliminates the effects of hub bolt press-fitting by providing multiple screw holes in the wheel mounting flange and fastening the brake rotor and wheel by threading wheel bolts inserted from the outside into each screw hole. The configuration in Patent Document 1, or this configuration, provides ribs around the bolt holes or screw holes in particular, thereby ensuring the rigidity of the bearing during use and reducing the weight of the device. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2007-203949 Summary of the Invention [Problem to be solved by the invention]

[0006] However, it was difficult to improve the runout accuracy of the wheel mounting flange simply by ensuring rigidity during use. Therefore, the inventors discovered through analysis and experimentation that slight variations in the tightening force of the wheel bolts in each screw hole lead to variations in deformation around each screw hole, and that these variations in deformation around each screw hole generally lead to a deterioration in the runout accuracy of the wheel mounting flange.

[0007] The inventors then discovered that it is necessary to specify the dimensional relationships between the various parts of the wheel mounting flange in order to not only ensure the rigidity of the wheel bearing device during use, but also to reduce the effects of variations in the tightening force of the wheel bolts.

[0008] SUMMARY OF THE INVENTION An object of the present invention is to provide a wheel bearing device that suppresses runout of the wheel mounting flange due to bolt fastening by specifying the dimensional relationships between the various parts of the wheel mounting flange. [Means for solving the problem]

[0009] The wheel bearing device of the present invention comprises an outer member having a double-row outer raceway surface on its inner periphery, an inner member having a double-row inner raceway surface opposing the double-row outer raceway surface, and double-row rolling elements accommodated in a rollable manner between the raceway surfaces of the outer member and the inner member, wherein one of the outer member or the inner member has a wheel mounting flange, and the wheel mounting flange has a plurality of screw holes into which wheel bolts for fixing a wheel and a brake rotor are screwed, and ribs provided on inner side peripheral edges of the screw holes, and wherein a nominal diameter of the screw holes is A, and in a cross section passing through the center of the screw holes and tangent to the pitch circle of the screw holes, The thickness direction of the inclined surface formed between the upper surface of the rib and the inner side surface of the disk portion of the wheel mounting flange When the width dimension of the portion passing through the center is B and the thickness direction dimension of the wheel mounting flange passing through the rib is C, the relationship is characterized in that B / A≧1.7 and C / A≧0.8.

[0010] Further, a wheel bearing device of the present invention comprises an outer member having a double-row outer raceway surface on its inner periphery, an inner member having a double-row inner raceway surface opposing the double-row outer raceway surface, and double-row rolling elements accommodated in a rollable manner between the raceway surfaces of the outer member and the inner member, wherein one of the outer member or the inner member has a wheel mounting flange, and the wheel mounting flange has a plurality of screw holes into which bolts for fixing only the brake rotor are screwed, and ribs provided on inner side peripheral edges of the screw holes, and the nominal diameter of the screw holes is E, and in a cross section passing through the center of the screw holes and tangent to the pitch circle of the screw holes, The thickness direction of the inclined surface formed between the upper surface of the rib and the inner side surface of the disk portion of the wheel mounting flange When the width dimension of the portion passing through the center is F and the thickness dimension of the wheel mounting flange passing through the rib is G, the relationship F / E≧1.7 and G / E≧0.8 is satisfied. [Effects of the Invention]

[0011] According to the present invention, by specifying the dimensions of the rib around the screw hole in the wheel mounting flange in a wheel bearing device, deformation around the screw hole due to bolt tightening can be suppressed, thereby suppressing runout of the wheel mounting flange. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a wheel bearing device according to an embodiment; [Figure 2] FIG. 2 is a side view of the hub wheel of FIG. 1 as seen from the inner side. [Figure 3] XX cross-sectional view of FIG. 2. [Figure 4] FIG. 3 is a cross-sectional view of FIG. 2 taken along the line Y-Y. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Overall configuration of wheel bearing device] The overall configuration of the wheel support bearing device 1 will be described using Figure 1. In the following description, the inner side refers to the vehicle body side of the wheel support bearing device 1 when attached to the vehicle body, and the outer side refers to the wheel side of the wheel support bearing device 1 when attached to the vehicle body. The axial direction refers to the direction along the rotation axis R of the wheel support bearing device 1. The radial direction refers to the direction perpendicular to the rotation axis R.

[0014] 1, the wheel bearing device 1 rotatably supports a wheel in a suspension system of a vehicle such as an automobile. The wheel bearing device 1 includes an outer ring 2 as an example of an outer member, a hub ring 3 and an inner ring 4 as examples of inner members, a rolling element 5, an inner seal member 6, and an outer seal member 7.

[0015] The outer ring 2 supports the hub ring 3 and the inner ring 4. The inner peripheral surface of the inner end 2g of the outer ring 2 is provided with an inner fitting surface 2b for fitting an inner seal member 6. The inner peripheral surface of the outer end 2f of the outer ring 2 is provided with an outer fitting surface 2c for fitting an outer seal member 7. The outer peripheral surface 2e of the outer ring 2 is integrally formed with a vehicle body mounting flange 2d for mounting to a knuckle of a suspension system (not shown). The inner peripheral surface of the outer ring 2 is provided with double-row outer raceways 2a / 2a on both the inner and outer sides in the circumferential direction.

[0016] The hub wheel 3 rotatably supports a vehicle wheel (not shown). The inner end of the outer peripheral surface of the hub wheel 3 is provided with a small-diameter step 3a that extends axially and is reduced in diameter. A wheel mounting flange 3b for mounting a wheel is integrally formed with the outer end of the hub wheel 3. The wheel mounting flange 3b is provided with a plurality of threaded holes 31 into which wheel bolts 83 that secure the wheel 81 and brake rotor 82 of the wheel are threaded, and a plurality of threaded holes 32 into which bolts 84 that secure only the brake rotor 82 are threaded. The outer outer peripheral surface of the hub wheel 3 is provided with an inner raceway surface 3d that faces the outer outer raceway surface 2a. In other words, the inner raceway surface 3d is defined by the hub wheel 3 on the outer side of the inner member. A sliding contact surface 3e with which the outer seal member 7 slides is provided on the base side of the wheel mounting flange 3b of the hub wheel 3.

[0017] The inner ring 4 is press-fitted into the small diameter step 3a of the hub ring 3. The inner ring 4 applies preload to the rolling elements 5. The outer peripheral surface of the inner ring 4 is provided with an inner raceway surface 4a that faces the inner-side outer raceway surface 2a. In other words, the inner raceway surface 4a is formed by the inner ring 4 on the inner side of the inner member. In addition, the outer peripheral surface of the inner-side end portion 4c of the inner ring 4 is provided with a fitting surface 4b into which the inner-side seal member 6 is fitted.

[0018] The rolling elements 5 are composed of balls. The inner-side rolling elements 5 and the outer-side rolling elements 5 are each held in a cage 51. The inner-side rolling elements 5 are rollably sandwiched between the inner raceway surface 4a of the inner ring 4 and the inner-side outer raceway surface 2a of the outer ring 2. The outer-side rolling elements 5 are rollably sandwiched between the inner raceway surface 3d of the hub ring 3 and the outer-side outer raceway surface 2a of the outer ring 2. In other words, the inner-side rolling elements 5 and the outer-side rolling elements 5 are rollably housed between the raceway surfaces of the outer member and the inner member. In this way, in the wheel bearing device 1, the outer ring 2, the hub ring 3, the inner ring 4, and the double-row rolling elements 5 form a double-row angular contact ball bearing. Note that the wheel bearing device 1 may be configured as a double-row tapered roller bearing instead of a double-row angular contact ball bearing.

[0019] The inner seal member 6 and the outer seal member 7 are formed by an outer member and an inner member, and are seal members that close the open ends of the annular space S filled with a required amount of lubricating grease. The inner seal member 6 is attached to the inner open end of the annular space S, which is formed between the outer ring 2 and the inner ring 4. On the other hand, the outer seal member 7 is attached to the outer open end of the annular space S, which is formed between the outer ring 2 and the hub wheel 3.

[0020] [Wheel mounting flange configuration] 2 is a side view of the hub wheel 3 of FIG. 1 as seen from the inner side, FIG. 3 is a cross-sectional view taken along line XX in FIG. 2, and FIG. 4 is a cross-sectional view taken along line YY in FIG.

[0021] As shown in Figure 2, the wheel mounting flange 3b has a disk portion 30, four screw holes 31, two screw holes 32, a rib 35 provided on the inner periphery of each screw hole 31, and a rib 36 provided on the inner periphery of each screw hole 32.

[0022] The disk portion 30 is a disk having an inner side surface 33 and an outer side surface 34, and forms the radial outer shape of the wheel mounting flange 3b. There are no particular limitations on the outer shape of the disk portion 30, as long as it is a shape that is radially larger than the ribs 35, 36.

[0023] The screw holes 31 are tapped holes that penetrate in the axial direction. The nominal diameter of the screw holes 31 is, for example, M12, M14, etc. The screw holes 31 are provided at equal intervals on a pitch circle of a predetermined diameter centered on the rotation axis R. There is no particular limitation on the number of screw holes 31 as long as there are two or more, and the screw holes may be arranged unevenly. As shown in FIG. 1 , a brake rotor 82 is attached to the outer side surface 34 of the disc portion 30, and a wheel 81 is attached to the outer side of the brake rotor 82, and the wheel 81 and the brake rotor 82 are fixed together with wheel bolts 83.

[0024] The screw holes 32 are tapped holes that penetrate in the axial direction. The screw holes 32 are evenly spaced on a pitch circle of a predetermined diameter centered on the rotation axis R. In this embodiment, the pitch circle diameter of the screw holes 32 is equal to, but may be different from, the pitch circle diameter of the screw holes 31. The number of screw holes 32 is not particularly limited as long as there are two or more screw holes 32, and the screw holes may be unevenly spaced. As shown in FIG. 1 , the brake rotor 82 is attached to the outer side surface 34 of the wheel mounting flange 3b and fixed with bolts 84. This prevents the brake rotor 82 from falling off even when the wheel bolts 83 and wheel 81 are not attached. In this embodiment, the nominal diameter of the screw holes 32 is smaller than the nominal diameter of the screw holes 31, but the nominal diameter of the screw holes 32 may be equal to or larger than the nominal diameter of the screw holes 31.

[0025] 2, the ribs 35 are protrusions provided on the peripheries of the four screw holes 31 on the inner side surface 33 of the disk portion 30. The ribs 35 have a substantially flat upper surface 35a and inclined surfaces 35b that incline from the upper surface 35a to the inner side surface 33 of the disk portion 30. When viewed from the inner side, the ribs 35 extend radially outward from the sliding surface 3e and are configured in a substantially arch shape.

[0026] The ribs 36 are protrusions provided on the peripheries of the two screw holes 32 on the inner side surface 33 of the disc portion 30. The ribs 36 have a substantially flat upper surface 36a and an inclined surface 36b that inclines from the upper surface 36a to the inner side surface 33 of the disc portion 30. When viewed from the inner side, the ribs 36 extend radially outward from the sliding surface 3e and are configured in a substantially arch shape. To maintain balance during rotation, the ribs 36 are also provided at two locations between the ribs 35 where no screw holes 32 are provided. In other words, four ribs 36 are provided between four ribs 35, respectively.

[0027] Next, the dimensional relationships of the various parts of the wheel mounting flange 3b will be defined. The dimensional relationships around the screw hole 31 and the dimensional relationships around the screw hole 36 will be explained separately below.

[0028] As shown in Figure 3, the nominal diameter of the screw hole 31 is A. In addition, in a cross section (cross section XX in Figure 2) that passes through the center of the screw hole 31 and is tangent to the pitch circle of the screw hole 31, the width dimension of the rib 35 is B, and the thickness dimension of the wheel mounting flange 3b that passes through the rib 35 is C. The width dimension B of the rib 35 is the dimension of a portion that passes through the center of the rib 35 in the thickness direction.

[0029] In this case, the lower limits of B / A and C / A are B / A≧1.7 and C / A≧0.8 in order to ensure the rigidity (deformation resistance) around the screw holes 31 of the rib 35. This ensures sufficient area and thickness for the rib 35, and suppresses deformation around the screw holes 31 due to fastening of the wheel bolts 83. As a result, runout of the wheel mounting flange 3b can be suppressed, and brake judder can be suppressed. Note that if B / A<1.7 or C / A<0.8, the areas around the screw holes 31 are likely to deform when the wheel bolts 83 are fastened.

[0030] Furthermore, from the viewpoint of weight reduction, the upper limits of B / A and C / A are preferably B / A<3.5 and C / A<1.2. This allows for sufficient weight reduction compared to when ribs 35 are provided on the entire inner side surface 33 of the disk portion 30. However, if B / A≧3.5 or C / A≧1.2, sufficient weight reduction effect cannot be obtained.

[0031] Furthermore, if the thickness dimension of the wheel mounting flange 3b without the rib 35, that is, the thickness dimension of the disc portion 30, is D, then the lower limit of D / C is preferably D / C≧0.45, and more preferably D / C≧0.5, in order to ensure rigidity around the screw holes 31 of the rib 35. This ensures sufficient area and thickness for the rib 35, and suppresses deformation around the screw holes 31 due to fastening of the wheel bolts 83. As a result, runout of the wheel mounting flange 3b can be suppressed, and brake judder can be suppressed.

[0032] From the viewpoint of weight reduction, the upper limit of D / C is preferably D / C<0.75, and more preferably D / C<0.7, which allows for a sufficient weight reduction compared to when the ribs 35 are provided on the entire inner side surface 33 of the disk portion 30.

[0033] As shown in Figure 4, the nominal diameter of the screw hole 32 is E. In addition, in a cross section (YY cross section in Figure 2) that passes through the center of the screw hole 32 and is tangent to the pitch circle of the screw hole 32, the width dimension of the rib 36 is F, and the thickness dimension of the wheel mounting flange 3b that passes through the rib 36 is G. The width dimension F of the rib 36 is the dimension of a portion that passes through the center of the rib 36 in the thickness direction.

[0034] In this case, the lower limit values ​​of F / E and G / E are F / E≧1.7≦ and G / E≧0.8, in order to ensure the rigidity around the screw holes 32 of the rib 36. This ensures sufficient area and thickness for the rib 36, and suppresses deformation around the screw holes 32 due to fastening of the bolts 84. As a result, runout of the wheel mounting flange 3b can be suppressed, and the occurrence of brake judder can be suppressed. Note that if F / E<1.7 or G / E<0.8, the areas around the screw holes 32 are likely to deform when the bolts 84 are fastened.

[0035] Furthermore, from the viewpoint of weight reduction, the upper limits of F / E and G / E are preferably F / E<3.5 and G / E<1.2. This allows for sufficient weight reduction compared to when ribs 36 are provided on the entire inner side surface 33 of the disk portion 30. However, if F / E≧3.5 or G / E≧1.2, sufficient weight reduction effect cannot be obtained.

[0036] In the wheel mounting flange 3b, it is preferable that the runout of a region 34a (see FIG. 1) on the outer side surface 34 that is radially outward from the pitch circle of the screw holes 31, 32 is 50 μm or less. The runout is the range of axial displacement of the region 34a of the outer side surface 34 when the hub wheel 3 is rotated about the rotation axis R. This reduces the runout of the brake rotor 82 fastened to the wheel mounting flange 3b, thereby suppressing the occurrence of brake judder.

[0037] Although the present embodiment has been described with reference to the wheel bearing device 1 for a driven wheel, the present invention can also be applied to a wheel bearing device for a driving wheel.

[0038] The wheel bearing device 1 of this embodiment has been described above as a wheel bearing device with an inner ring rotation third-generation structure in which the inner raceway surface 3d of the rolling element 5 is formed directly on the outer periphery of the hub ring 3. However, the present invention is not limited to this. For example, the wheel bearing device may have an inner ring rotation second-generation structure in which a pair of inner rings are press-fitted into the hub ring, or a first-generation structure that does not have a mounting flange for the vehicle body. The wheel bearing device may also have an outer ring rotation second-generation structure or a first-generation structure. In the case of an outer ring rotation wheel bearing device, the wheel mounting flange is provided on the outer ring (outer member). Furthermore, the above-described embodiment merely illustrates a typical form of the present invention, and various modifications can be made without departing from the gist of the present invention. Therefore, as long as a similar wheel mounting flange is provided, the wheel bearing device may have a so-called fourth-generation structure in which the wheel bearing device and a constant velocity universal joint for driving are integrated. [Explanation of symbols]

[0039] 1 Wheel bearing device 2 Outer ring (outer member) 2a Outer raceway surface 3 Hub ring (inner part) 3b Wheel mounting flange 3d, 4a inner raceway surface 4 Inner ring (inner part) 5 rolling elements 31 screw holes 32 screw holes 34 outer side 35 Ribs 36 Ribs 83 Wheel bolts 84 volts

Claims

1. an outer member having a double-row outer raceway surface on its inner periphery; an inner member having a double-row inner raceway surface facing the double-row outer raceway surface; a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member, one of the outer member or the inner member has a wheel mounting flange; The wheel mounting flange has a plurality of screw holes into which wheel bolts for fixing the wheel and the brake rotor are screwed, and ribs provided on inner peripheral edges of the screw holes, The nominal diameter of the screw hole is A, In a cross section passing through the center of the screw hole and tangent to the pitch circle of the screw hole, the width dimension of a portion passing through the center in the thickness direction of the inclined surface formed between the upper surface of the rib and the inner side surface of the disc portion of the wheel mounting flange is defined as B, and the thickness direction dimension of the wheel mounting flange passing through the rib is defined as C. A wheel bearing device, characterized in that B / A≧1.7 and C / A≧0.

8.

2. 2. The wheel bearing device according to claim 1, wherein B / A<3.5 and C / A<1.

2.

3. If the thickness direction dimension of the wheel mounting flange where the rib is not provided is D, 3. The wheel bearing device according to claim 1, wherein D / C is greater than or equal to 0.

45.

4. 4. The wheel bearing device according to claim 3, wherein D / C<0.

75.

5. an outer member having a double-row outer raceway surface on its inner periphery; an inner member having a double-row inner raceway surface facing the double-row outer raceway surface; a double row of rolling elements rollably accommodated between the raceway surfaces of the outer member and the inner member, one of the outer member or the inner member has a wheel mounting flange; the wheel mounting flange has a plurality of screw holes into which bolts for fixing only the brake rotor are screwed, and ribs provided on inner peripheral edges of the screw holes, The nominal diameter of the screw hole is E, In a cross section that passes through the center of the screw hole and is tangent to the pitch circle of the screw hole, if the width dimension of a portion that passes through the center in the thickness direction of the inclined surface formed between the upper surface of the rib and the inner side surface of the disc portion of the wheel mounting flange is F and the thickness dimension of the wheel mounting flange that passes through the rib is G, then: A wheel bearing device, characterized in that F / E≧1.7 and G / E≧0.

8.

6. 6. The wheel bearing device according to claim 5, wherein F / E<3.5 and G / E<1.

2.

7. 7. The wheel bearing device according to claim 1, wherein runout in a region radially outward of a pitch circle of the screw hole on the outer side surface of the wheel mounting flange is 50 μm or less.

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