Wheel bearing device

Abstract

To provide a bearing device for a wheel which enables restriction on the design of internal specification to be suppressed and furthermore the maintainability thereof to be improved.SOLUTION: A bearing device 1 for a wheel comprises: an outer ring 2; inner raceway grooves in double rows which are opposed to outer raceway grooves in double rows of the outer ring 2; an inner member (hub ring 3 and inner ring 4) which has a wheel fitting flange 32; ball lines 5, 6 in double rows; and a hub bolt 36 which is press-fit to a bolt hole 35 of the wheel fitting flange 32. The outer ring 2 comprises: a first outer periphery 27; a second outer periphery 28 having a smaller diameter than that of the first outer periphery 27; a difference-in-level surface 29 which connects the first outer periphery 27 with the second outer periphery 28. The outer diameter radial dimension R2 of the first outer periphery 27 is larger than the inscribed circle radius R0 of a head portion 361 in a hub bolt 36 that is press-fit to the bolt hole 35. The outer diameter radial dimension R3 of the second outer periphery 28 is smaller than the inscribed circle radius R0 of the head portion 361 in the hub bolt 36 that is press-fit to the bolt hole 35.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Wheel bearing devices that rotatably support wheels in suspension systems for vehicles such as automobiles are known. In wheel bearing devices, a hub ring, which is an inner member, has a hub flange that extends radially outward, and hub bolts for fastening the hub ring to the wheel or the like are press-fitted into bolt holes formed in the hub flange.

[0003] When designing the internal specifications of a wheel bearing assembly, increasing the pitch circle diameter (PCD) and ball diameter of the balls housed between the raceways of the outer and inner members is effective in improving durability and resistance to indentations as the vehicle weight increases. Furthermore, to prevent hardening when induction hardening is performed on the outer raceway of the outer member, it is necessary to ensure a certain thickness between the bottom of the outer raceway and the outer peripheral surface of the outer member.

[0004] In this way, if the pitch circle diameter or ball diameter of the ball is increased, or the thickness of the outer member is increased, the outer diameter dimension of the outer surface of the outer member will become larger, and when pulling out the hub bolt pressed into the hub flange, the hub flange and the outer surface of the outer member will interfere with each other, making it impossible to pull out the hub bolt, which may reduce the maintainability of the wheel bearing device.

[0005] To solve this problem, Patent Document 1 discloses a wheel bearing device in which a guide groove is formed in the outer diameter portion of a thick portion provided at the outer end of the outer ring, which is the outer member, to guide the hub bolt along the rotation axis. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 6725993 Summary of the Invention [Problem to be solved by the invention]

[0007] However, forming a guide groove on the outer diameter portion of the outer ring, as in the wheel support bearing device disclosed in Patent Document 1, restricts the outer diameter dimension of the outer ring at the portion where the guide groove is formed, which places restrictions on the design of internal specifications such as the pitch circle diameter and ball diameter of the balls, and makes it difficult to ensure the wall thickness of the outer ring, which may make it impossible to design a wheel support bearing device with sufficient durability. This problem is particularly noticeable in wheel support bearing devices in which the hub bolts are located on the inner diameter side in order to make them more compact.

[0008] The present invention has been made in consideration of the above circumstances, and aims to provide a wheel bearing device that can improve maintainability while minimizing restrictions on the design of internal specifications. [Means for solving the problem]

[0009] That is, the wheel bearing device is a wheel bearing device comprising: an outer member having double-row outer raceway grooves on its inner circumference; double-row inner raceway grooves opposing the double-row outer raceway grooves; an inner member having a hub flange at one axial end extending radially outward; double-row rolling elements accommodated in a rollable manner between the raceway grooves of the outer member and the inner member; and a hub bolt press-fitted into a bolt hole formed in the hub flange, wherein the outer member has a first outer periphery located on the outer diameter side of the bottom of the outer raceway groove at one axial end. a second outer peripheral surface located axially closer to the hub flange than the first outer peripheral surface and having a smaller diameter than the first outer peripheral surface; and a stepped surface located axially between the first outer peripheral surface and the second outer peripheral surface and connecting the first outer peripheral surface and the second outer peripheral surface, wherein the outer radius of the first outer peripheral surface is larger than the inscribed circle radius of the head of the hub bolt pressed into the bolt hole, and the outer radius of the second outer peripheral surface is smaller than the inscribed circle radius of the head of the hub bolt pressed into the bolt hole. [Effects of the Invention]

[0010] According to the present invention, it is possible to improve the maintainability of the wheel support bearing device while suppressing restrictions on the design of the internal specifications of the wheel support bearing device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a side cross-sectional view showing a wheel bearing device. [Figure 2] FIG. [Figure 3] 10 is a side cross-sectional view showing the wheel bearing device in a state in which the head of the hub bolt press-fitted into the bolt hole and the second outer peripheral surface of the outer ring are spaced apart in the radial direction. FIG. [Figure 4] 10 is a side cross-sectional view showing a stepped surface formed by a curved surface that is concave toward the outer diameter side. FIG. [Figure 5] 10 is a side cross-sectional view showing a stepped surface formed by a curved surface that is convex toward the outer diameter side. FIG. [Figure 6] 10 is a side cross-sectional view showing the wheel bearing device in a state where the head of the hub bolt has been pulled out of the bolt hole in the axial direction and is in contact with the contact portion of the stepped surface. FIG. [Figure 7] FIG. 10 is a side cross-sectional view showing the inclined surface of the bolt hole. [Figure 8] 10A to 10C are diagrams showing the procedure for removing the hub bolt from the bolt hole. [Figure 9] 10 is a cross-sectional side view of the wheel bearing device in a state where the hub bolt has been translated radially outward in a translational translation process. FIG. [Figure 10] 10 is a cross-sectional side view of the wheel bearing device in a state where the wheel bearing device has been pulled further inward along the axial direction until the head portion comes into contact with the stepped surface in an additional pulling-out process. FIG. [Figure 11] 10 is a side cross-sectional view showing the wheel bearing device in a state in which the hub bolt is tilted in the axial direction so that the head is positioned radially outward from the shaft portion during a tilting process. FIG. [Figure 12]10 is a cross-sectional side view of the wheel bearing device in a state where the hub bolt has been pulled out of the bolt hole along the tilted direction in a complete pulling-out process. FIG. [Figure 13] 10A to 10C are diagrams illustrating a procedure for press-fitting a hub bolt into a bolt hole. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0013] [Wheel bearing device] A wheel bearing device 1 shown in FIG. 1 is one embodiment of a wheel bearing device according to the present invention, and supports a wheel rotatably in a suspension system of a vehicle such as an automobile.

[0014] The wheel bearing device 1 has a configuration known as the third generation, and includes an outer ring 2 as an outer member, a hub ring 3 and an inner ring 4 as inner members, two rolling rows of inner ball rows 5 and outer ball rows 6, an outer seal member 9, and an inner seal member 10.

[0015] In the following description, the axial direction refers to the direction along the rotation axis X of the wheel support bearing device 1. Furthermore, the outer side refers to one axial end side, which is the wheel side of the wheel support bearing device 1 when attached to the vehicle body, and the inner side refers to the other axial end side, which is the vehicle body side of the wheel support bearing device 1 when attached to the vehicle body.

[0016] An inner side opening 21 is formed at the inner side end of the outer ring 2, into which an inner side seal member 10 can be fitted. An outer side opening 22 is formed at the outer side end of the outer ring 2, into which an outer side seal member 9 can be fitted.

[0017] The inner-side seal member 10 is fitted into the inner-side opening 21, thereby closing the inner-side opening end of the annular space S formed by the outer ring 2, which is the outer member, and the hub ring 3 and inner ring 4, which are the inner members. The outer-side seal member 9 is fitted into the outer-side opening 22, thereby closing the outer-side opening end of the annular space S.

[0018] The inner seal member 10 and the outer seal member 9 are sealing devices that close the open ends of the annular space S. In this way, by closing the open ends on the inner and outer sides of the annular space S with the inner seal member 10 and the outer seal member 9, foreign matter such as muddy water is prevented from entering the inside of the wheel bearing device 1.

[0019] An inner-side outer raceway groove 23 and an outer-side outer raceway groove 24 are formed on the inner peripheral surface of the outer ring 2. A vehicle body mounting flange 25 for mounting the outer ring 2 to a vehicle body member is integrally formed on the outer peripheral surface of the outer ring 2. The vehicle body mounting flange 25 is provided with bolt holes 26 into which fastening members (here, bolts) are inserted to fasten the outer ring 2 to the vehicle body member.

[0020] A small-diameter step 31, which is smaller in diameter than the outer end, is formed at the inner end of the outer peripheral surface of the hub wheel 3. A wheel mounting flange 32, for mounting a wheel, is formed integrally with the outer end of the hub wheel 3. The wheel mounting flange 32 is an example of a hub flange. A plurality of bolt holes 35 are formed in the wheel mounting flange 32. Hub bolts 36, for fastening the hub wheel 3 to a wheel or brake component, can be press-fitted into the bolt holes 35.

[0021] In the hub ring 3, a sliding surface 34 with which the outer seal member 9 slides is formed on the base side of the wheel mounting flange 32. An outer inner raceway groove 33 is provided on the outer peripheral surface of the hub ring 3 so as to face the outer outer raceway groove 24 on the outer side of the outer ring 2. In other words, the hub ring 3 defines the inner raceway groove 33 on the outer side of the inner member.

[0022] An inner ring 4 is provided on the small diameter step 31 of the hub ring 3. The inner ring 4 is fixed to the small diameter step 31 of the hub ring 3 by press fitting. An inner-side inner raceway groove 41 is provided on the outer peripheral surface of the inner ring 4 so as to face the inner-side outer raceway groove 23 of the outer ring 2. In other words, the inner ring 4 defines the inner raceway groove 41 on the inner side of the inner member.

[0023] The inner ball row 5 and outer ball row 6, which are rolling rows, are formed by a plurality of balls 7, which are rolling elements, being held in a cage 8. The inner ball row 5 is rollably sandwiched between the inner raceway groove 41 of the inner ring 4 and the outer raceway groove 23 on the inner side of the outer ring 2. The outer ball row 6 is rollably sandwiched between the inner raceway groove 33 of the hub ring 3 and the outer raceway groove 24 on the outer side of the outer ring 2. In other words, the inner ball row 5 and the outer ball row 6 are rollably housed between the raceway grooves of the outer member and the inner member.

[0024] In the wheel bearing device 1, a double-row angular contact ball bearing is formed by the outer ring 2, hub ring 3, inner ring 4, inner ball row 5, and outer ball row 6. Note that the wheel bearing device 1 may be formed as a double-row tapered roller bearing instead of the double-row angular contact ball bearing.

[0025] [Hub bolt] 2, the hub bolt 36 includes a head 361, a knurled portion 362, a shaft portion 363, and an externally threaded portion 364. The head 361 is located at the inner end of the hub bolt 36 when the hub bolt 36 is press-fitted into the bolt hole 35. The head 361 is located on the inner side of the wheel mounting flange 32. The head 361 has an outer diameter D1.

[0026] The knurl portion 362 is a portion that is press-fitted into the bolt hole 35 of the hub bolt 36, and multiple axially extending knurls are formed in the circumferential direction in the knurl portion 362. The knurl portion 362 is located adjacent to the outer side of the head portion 361, and has an outer diameter D2 that is smaller than the outer diameter D1 of the head portion 361.

[0027] The shaft portion 363 is located adjacent to the outer side of the knurl portion 362, and has an outer diameter D3 that is smaller than the outer diameter D2 of the knurl portion 362. The male threaded portion 364 is located adjacent to the outer side of the shaft portion 363, and has an outer diameter D4 that is approximately the same as the outer diameter D3 of the shaft portion 363. By threading a nut onto the male threaded portion 364 of the hub bolt 36 that is press-fitted into the bolt hole 35, the hub wheel 3 can be fastened to the wheel or brake component.

[0028] 3, the hub bolt 36 can be press-fitted into the bolt hole 35 from the inner side of the wheel mounting flange 32, and the head 361 of the hub bolt 36 press-fitted into the bolt hole 35 contacts the inner end face 321 of the wheel mounting flange 32. The inner end face 321 is an example of the other end face in the axial direction of the hub flange.

[0029] The inscribed circle radius of the head 361 of the hub bolt 36 press-fitted into the bolt hole 35 is R0. The inscribed circle radius R0 is the length in the radial direction between the rotation axis X and the point of the head 361 closest to the rotation axis X. In other words, the inscribed circle radius R0 is the radius of a circle whose center is the rotation axis X and which is tangent to the point of the head 361 closest to the rotation axis X.

[0030] [Outer ring] As shown in Fig. 3, the outer raceway groove 24 on the outer side of the outer ring 2 has a bottom 24a. The bottom 24a is the portion of the outer raceway groove 24 where the inner radius dimension from the rotational axis X of the wheel bearing device 1 is the largest. The inner radius dimension from the rotational axis X of the bottom 24a is an inner radius dimension R1. The inner radius dimension R1 is a dimension determined by the internal specifications of the wheel bearing device 1, such as the pitch circle diameter (PCD) and diameter of the balls 7.

[0031] The outer ring 2 has a first outer peripheral surface 27, a second outer peripheral surface 28, and a stepped surface 29. The first outer peripheral surface 27 is located on the outer diameter side of the bottom portion 24a of the outer raceway groove 24 on the outer side.

[0032] The outer ring 2 has a radial thickness d between the bottom portion 24a and the first outer peripheral surface 27. The thickness d is determined, for example, in consideration of the dimension necessary to prevent hardening-through when induction hardening is performed on the outer raceway groove 24. The outer radius of the first outer peripheral surface 27 from the rotation axis X is an outer radius R2. The outer radius R2 can be set to at least a value obtained by adding the thickness d of the outer ring 2 to the inner radius R1 of the bottom portion 24a.

[0033] The second outer peripheral surface 28 is located at the outer end of the outer ring 2, closer to the wheel mounting flange 32 in the axial direction than the first outer peripheral surface 27. The outer radius of the second outer peripheral surface 28 from the rotation axis X is an outer radius R3. The outer radius R3 is formed to be smaller than the outer radius R2 of the first outer peripheral surface 27.

[0034] The step surface 29 is located between the first outer peripheral surface 27 and the second outer peripheral surface 28 in the axial direction, and connects the first outer peripheral surface 27 and the second outer peripheral surface 28. An inner end of the step surface 29 is connected to the first outer peripheral surface 27, and an outer end of the step surface 29 is connected to the second outer peripheral surface 28.

[0035] The step surface 29 is formed by a tapered surface that linearly increases in diameter from the outer end to the inner end. However, the step surface 29 can also be formed by a curved surface that increases in diameter from the outer end to the inner end and is concave toward the outer diameter side, as in step surface 29A shown in Fig. 4. The step surface 29 can also be formed by a curved surface that increases in diameter from the outer end to the inner end and is convex toward the outer diameter side, as in step surface 29B shown in Fig. 5.

[0036] In this way, by making it possible to form step surface 29 as a tapered surface, a curved surface that is concave toward the outer diameter side, or a curved surface that is convex toward the outer diameter side, the degree of freedom in designing the external shape of outer ring 2 can be increased.

[0037] The first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 can be formed by forging. Alternatively, the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 can be formed by forging the outer ring 2 and then turning the outer peripheral surface of the outer ring 2. In other words, the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 can be formed to have a forged surface or a turned surface.

[0038] When the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 are formed to have a forged texture during forging, there is no need to perform turning on the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29, which simplifies the manufacturing process of the wheel bearing device 1. On the other hand, when the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 are turned to have a turned surface, the outer diameter shapes and outer radius dimensions of the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29 can be finished with high precision.

[0039] The outer diameter radius dimension R2 of the first outer peripheral surface 27 is formed larger than the inscribed circle radius R0 of the head 361 of the hub bolt 36 press-fitted into the bolt hole 35 (R2>R0), and the outer diameter radius dimension R3 of the second outer peripheral surface 28 is formed smaller than the inscribed circle radius R0 of the head 361 of the hub bolt 36 press-fitted into the bolt hole 35 (R3 <R0)。

[0040] The head 361 of the hub bolt 36 pressed into the bolt hole 35 and the second outer peripheral surface 28 of the outer ring 2 are positioned overlapping in the axial direction, but since the outer diameter radius dimension R3 of the second outer peripheral surface 28 is formed smaller than the inscribed circle radius R0 of the head 361, the head 361 of the hub bolt 36 pressed into the bolt hole 35 and the second outer peripheral surface 28 of the outer ring 2 are spaced apart in the radial direction and do not interfere with each other.

[0041] 6, the outer diameter radius dimension R2 of the first outer peripheral surface 27 is formed to be larger than the inscribed circle radius R0 of the head 361 of the hub bolt 36 press-fitted into the bolt hole 35, so when the hub bolt 36 press-fitted into the bolt hole 35 is pulled outward in the axial direction, the head 361 of the hub bolt 36 comes into contact with the contact portion 291 of the stepped surface 29. The contact portion 291 is the portion with which the head 361 of the hub bolt 36 comes into contact when the hub bolt 36 press-fitted into the bolt hole 35 is pulled out of the bolt hole 35 in the axial direction.

[0042] 3 and 6, the head 361 of the hub bolt 36 has a contacted portion 361a that comes into contact with the contact portion 291 of the stepped surface 29 when the hub bolt 36, which has been press-fitted into the bolt hole 35, is pulled out axially toward the inner side from the bolt hole 35. In the hub bolt 36, the dimension in the axial direction from the contacted portion 361a of the head 361 to the outer end 362a of the knurl portion 362 is L1.

[0043] As shown in FIG. 6, in the wheel bearing device 1, the dimension in the axial direction from the inner end surface 321 of the wheel mounting flange 32 to the contact portion 291 is L2. The dimension L2 is larger than the dimension L1 of the hub bolt 36 (L2>L1).

[0044] 7, bolt hole 35 of wheel mounting flange 32 has, at its inner end, an inclined surface 351 that increases in diameter as it goes inward. The inclination angle θ of inclined surface 351 with respect to the axial direction is set to be 45° or greater.

[0045] The outer peripheral surface of the outer ring 2, including the first outer peripheral surface 27, the second outer peripheral surface 28, and the step surface 29, does not have an uneven shape in the circumferential direction, as would be the case if a guide groove were formed on the outer peripheral surface of the outer ring 2 to guide the hub bolt 36 along the axial direction.

[0046] If guide grooves for guiding the hub bolts 36 were formed in the outer peripheral surface of the outer ring 2, the outer shape of the outer peripheral surface in the circumferential direction would become complex, which could reduce the life of the forging die for the outer ring 2 formed by a forging method. However, since the outer peripheral surface of the outer ring 2 does not have guide grooves for guiding the hub bolts 36 formed therein, and the outer shape of the outer peripheral surface in the circumferential direction is not complex, it is possible to prevent a reduction in the life of the forging die.

[0047] [Method for maintaining wheel bearing devices] Next, a description will be given of a maintenance method for the wheel bearing device 1 when performing maintenance on the wheel bearing device 1 by inserting and removing the hub bolt 36 into and from the bolt hole 35 of the wheel mounting flange 32. Specifically, the procedure for removing the hub bolt 36 that has been press-fitted into the bolt hole 35 from the bolt hole 35, and the procedure for press-fitting the hub bolt 36 into the bolt hole 35 will be described.

[0048] (Procedure for removing the hub bolt from the bolt hole) 3, when the hub bolt 36 is press-fitted into the bolt hole 35 of the wheel mounting flange 32, the head 361 of the hub bolt 36 is in contact with the inner end face 321 of the wheel mounting flange 32. The head 361 of the hub bolt 36 press-fitted into the bolt hole 35 and the second outer peripheral surface 28 of the outer ring 2 are positioned to overlap in the axial direction, and the stepped surface 29 and first outer peripheral surface 27 of the outer ring 2 are positioned on the inner side of the head 361.

[0049] When the hub bolt 36 thus press-fitted into the bolt hole 35 is pulled out from the bolt hole 35, a knurl pulling-out step S01 is first carried out as shown in FIG.

[0050] 6, in the knurl portion extraction step S01, the hub bolt 36 press-fitted into the bolt hole 35 is extracted axially toward the inner side until the contacted portion 361a of the head 361 contacts the contact portion 291 of the stepped surface 29. In this case, the dimension L2 from the inner end face 321 of the wheel mounting flange 32 to the contact portion 291 is larger than the dimension L1 from the contacted portion 361a of the head 361 to the outer end 362a of the knurl portion 362, so that the knurl portion 362 of the hub bolt 36 is completely extracted from the bolt hole 35.

[0051] After the knurl portion extraction step S01 is performed, the shaft portion 363 of the hub bolt 36 is positioned within the bolt hole 35. The shaft portion 363 has an outer diameter D3 that is smaller than the outer diameter D2 of the knurl portion 362, so there is a gap between the outer peripheral surface of the shaft portion 363 and the inner peripheral surface of the bolt hole 35.

[0052] After the knurl extraction step S01, a parallel movement step S02 is performed. As shown in Fig. 9, in the parallel movement step S02, the hub bolt 36 is translated outward until the outer peripheral surface of the shaft portion 363 contacts the inner peripheral surface of the bolt hole 35. By translating the hub bolt 36 outward, a gap is created between the head portion 361 and the contact portion 291 of the step surface 29, making it possible to move the hub bolt 36 further inward.

[0053] Even when the shaft 363 of the hub bolt 36 is brought into contact with the inner peripheral surface on the outer diameter side of the bolt hole 35 and the hub bolt 36 is positioned on the outermost diameter side within the bolt hole 35, the outer diameter radius dimension R2 of the first outer peripheral surface 27 is larger than the inscribed circle radius R4 of the head 361 of the hub bolt 36.

[0054] After the parallel movement step S02, an additional withdrawal step S03 is performed. As shown in Fig. 10, in the additional withdrawal step S03, the hub bolt 36 that has been translated toward the outer diameter side in the parallel movement step S02 is further pulled out toward the inner side along the axial direction until the head 361 contacts the stepped surface 29. In this case, the head 361 contacts the end of the stepped surface 29 on the first outer peripheral surface 27 side.

[0055] In other words, by positioning the hub bolt 36 at the outermost diameter side within the bolt hole 35, it can be pulled further inward from the position after the knurl portion pulling-out process S01 is performed, but since the outer diameter radius dimension R2 of the first outer surface 27 is larger than the inscribed circle radius R4 of the head 361 of the hub bolt 36 positioned at the outermost diameter side within the bolt hole 35, the head 361 abuts against the step surface 29.

[0056] In this way, in the additional pulling-out step S03, the knurl portion 362 pulled out from the bolt hole 35 can be moved to a position further away from the bolt hole 35 toward the inner side.

[0057] After the additional pulling-out step S03, a tilting step S04 is performed. As shown in Fig. 11, in the tilting step S04, the hub bolt 36 is tilted in the axial direction so that the head 361 is positioned radially outward of the shaft portion 363.

[0058] In this case, the hub bolt 36 is tilted until, for example, the shaft portion 363 contacts a portion of the inner circumferential surface of the bolt hole 35 located on the outer diameter side of the inner end, and the male thread portion 364 contacts a portion of the inner circumferential surface of the bolt hole 35 located on the inner diameter side of the outer end. By tilting the hub bolt 36 in this way, the head 361 of the hub bolt 36 moves away from the outer circumferential surface of the outer ring 2 toward the outer diameter side.

[0059] After the tilting step S04, a complete withdrawal step S05 is performed. As shown in Fig. 12, in the complete withdrawal step S05, the hub bolt 36 is withdrawn from the bolt hole 35 in the direction in which it was tilted in the tilting step S04. In this case, the hub bolt 36 is withdrawn until the male thread portion 364 is completely removed from the bolt hole 35.

[0060] In this way, by withdrawing the hub bolt 36 from the bolt hole 35 with the head 361 tilted axially toward the outer diameter side relative to the shaft portion 363, the hub bolt 36 can be withdrawn with the head 361 spaced outward from the outer peripheral surface of the outer ring 2. Therefore, even if the outer diameter radius dimension R2 of the first outer peripheral surface 27 of the outer ring 2 is formed to be larger than the inscribed circle radius R0 of the head 361 of the hub bolt 36, it is possible to completely withdraw the hub bolt 36 from the bolt hole 35.

[0061] Furthermore, in the wheel support bearing device 1, even if the outer diameter radius dimension R2 of the first outer peripheral surface 27 becomes larger than the inscribed circle radius R0 of the head 361 by designing the internal specifications with a larger ball pitch circle diameter or ball diameter, or by designing the outer ring 2 with a larger wall thickness at a location corresponding to the outer raceway groove 24 on the outer side, by forming the second outer peripheral surface 28 with a smaller diameter than the first outer peripheral surface 27 and the stepped surface 29 connecting the first outer peripheral surface 27 and the second outer peripheral surface 28, it is possible to completely pull out the hub bolt 36 from the bolt hole 35. This makes it possible to improve the maintainability of the wheel support bearing device 1 while minimizing restrictions on the design of the internal specifications of the wheel support bearing device 1.

[0062] In particular, in the wheel bearing device 1, the dimension L2 from the inner end face 321 of the wheel mounting flange 32 to the contact portion 291 is greater than the dimension L1 from the contacted portion 361a of the head portion 361 to the outer end portion 362a of the knurl portion 362, so when the hub bolt 36 is pulled out until the head portion 361 contacts the contact portion 291, the knurl portion 362 can be completely pulled out from the bolt hole 35. This makes it possible to easily tilt the hub bolt 36 axially after pulling the knurl portion 362 out of the bolt hole 35, facilitating the operation of pulling out the hub bolt 36.

[0063] Furthermore, when the hub bolt 36 is tilted until the shaft portion 363 contacts the portion located on the outer diameter side of the inner end portion on the inner surface of the bolt hole 35, the shaft portion 363 comes into contact with the inclined surface 351 formed on the inner end portion of the bolt hole 35.

[0064] In this case, the inclination angle θ of inclined surface 351 relative to the axial direction is set to a large angle such as 45° or more, so that hub bolt 36 can be inclined significantly relative to the axial direction, increasing the distance between head 361 and the outer peripheral surface of outer ring 2. This prevents head 361 from interfering with the outer peripheral surface of outer ring 2 when hub bolt 36 is pulled out along the inclined direction, making it possible to easily pull hub bolt 36 completely out of bolt hole 35.

[0065] Furthermore, although the step surface 29 in this embodiment is formed as a tapered surface that expands in diameter linearly, by forming the step surface 29 as a curved surface that is concave toward the outer diameter side, it is possible to pull the hub bolt 36 further inward when the hub bolt 36 is pulled out until the head 361 contacts the contact portion 291 of the step surface 29 in the knurl portion pulling-out step S01. This makes it possible to easily tilt the hub bolt 36 in the axial direction, making the work of pulling out the hub bolt 36 easier.

[0066] Furthermore, if the dimension L2 from the inner end face 321 of the wheel mounting flange 32 to the contact portion 291 is significantly larger than the dimension L1 from the contacted portion 361a of the head portion 361 to the outer end portion 362a of the knurl portion 362, it is possible to pull the hub bolt 36 further inward in the knurl portion extraction step S01. This makes it possible to easily tilt the hub bolt 36 axially, so that after the knurl portion extraction step S01, the tilting step S04 can be performed without going through the translation step S02 and the additional extraction step S03.

[0067] (Procedure for pressing the hub bolt into the bolt hole) As shown in FIG. 13, when the hub bolt 36 is press-fitted into the bolt hole 35 of the wheel mounting flange 32, an insertion step S11 is first carried out.

[0068] 12, in the insertion step S11, the hub bolt 36 is inserted into the bolt hole 35 from the inner side with the head 361 tilted axially toward the side where it is positioned more radially outward than the shank 363. As shown in FIG. 11, in the insertion step S11, the hub bolt 36 is inserted into the bolt hole 35 until the shank 363 enters the bolt hole 35.

[0069] After the insertion step S11, the axial alignment step S12 is performed. As shown in Fig. 10, in the axial alignment step S12, the hub bolt 36, which is tilted relative to the axial direction, is moved so that it is aligned with the axial direction. In this case, for example, the hub bolt 36 is moved to a position where the outer diameter side of the outer peripheral surface of the shaft portion 363 contacts the outer diameter side of the inner peripheral surface of the bolt hole 35. Thereafter, as shown in Fig. 9, the hub bolt 36 is moved toward the outer side along the axial direction until the outer end 362a of the knurl portion 362 is positioned near the inner end face 321 of the wheel mounting flange 32.

[0070] After the axially aligned step S12, a parallel movement step S13 is performed. As shown in Fig. 6, in the parallel movement step S13, the hub bolt 36 is translated inwardly to a position where the axis of the hub bolt 36 coincides with the center of the bolt hole 35. By translating the hub bolt 36 inwardly, the outer peripheral surface of the shaft portion 363 and the inner peripheral surface of the bolt hole 35 are separated from each other.

[0071] After the parallel movement step S13, a press-fitting step S14 is performed. As shown in Fig. 3, in the press-fitting step S14, the knurled portion 362 of the hub bolt 36 is press-fitted into the bolt hole 35. This completes the press-fitting of the hub bolt 36 into the bolt hole 35.

[0072] In this way, by inserting the hub bolt 36 into the bolt hole 35 with the head 361 tilted axially toward the outer diameter side than the shaft 363, and then moving the hub bolt 36 to a position along the axial direction and pressing it into the bolt hole 35, it becomes possible to press the hub bolt 36 into the bolt hole 35 even if the outer diameter radius dimension R2 of the first outer surface 27 of the outer ring 2 is formed larger than the inscribed circle radius R0 of the head 361 of the hub bolt 36.

[0073] Furthermore, for example, if the dimension L2 of the wheel bearing device 1 is significantly larger than the dimension L1 of the hub bolt 36, when moving the hub bolt 36, which is inclined relative to the axial direction, to an axial position in the axial direction in the axial step S12, the hub bolt 36 can be moved directly to a position where the axis of the hub bolt 36 and the center of the bolt hole 35 coincide, thereby making it possible to omit the parallel movement step S13 and proceed to the press-in step S14.

[0074] Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments, which are merely examples, and it goes without saying that the present invention can be embodied in various other forms without departing from the spirit of the present invention. The scope of the present invention is indicated by the claims, and further includes the equivalent meanings set forth in the claims, and all modifications within the scope of the claims. [Explanation of symbols]

[0075] 1 Wheel bearing device 2 outer ring 3 Hub Wheel 4. Inner Circle 5 Inner ball row 6 Outer ball row 23 (inner side) outer raceway groove 24 (Outer side) outer raceway groove 24a bottom 27 First outer surface 28 Second outer surface 29 Step surface 32 Wheel mounting flange 33 (Outer side) inner raceway groove 35 bolt holes 36 Hub bolt 41 (inner side) inner raceway groove 291 Contact part 321 Inner side end face 351 Slope 361 Head 361a Contacted part 362 Narl Department 362a Outer end 363 Shaft D1 (head) outer diameter D2 (Knurled part) outer diameter D3 (shaft) outer diameter L1 (distance from the contact part of the head to the outer end of the knurl) L2 (distance from inner end face of wheel mounting flange to contact area) R0 (radius of the inscribed circle when the hub bolt is press-fitted into the bolt hole) R2 (First outer surface) outer radius dimension R3 (second outer surface) outer radius dimension R4 (radius of the inscribed circle when the hub bolt shaft is in contact with the inner surface of the outer diameter side of the bolt hole) S01 Knurled part extraction process S04 Inclined process S05 Complete extraction process S11 Insertion process S12 Axial process S14 Press-fit process θ Tilt angle

Claims

1. an outer member having double-row outer raceway grooves on its inner periphery; an inner member having double rows of inner raceway grooves opposing the double rows of outer raceway grooves, and a hub flange extending radially outward from one axial end thereof; double-row rolling elements rollably accommodated between the raceway grooves of the outer member and the inner member; a hub bolt press-fitted into a bolt hole formed in the hub flange; A wheel bearing device comprising: The outer member is a first outer peripheral surface located on an outer diameter side of a bottom portion of the outer raceway groove at one axial end thereof; a second outer peripheral surface that is located closer to the hub flange than the first outer peripheral surface in the axial direction and has a smaller diameter than the first outer peripheral surface; a step surface located between the first outer peripheral surface and the second outer peripheral surface in the axial direction and connecting the first outer peripheral surface and the second outer peripheral surface, an outer diameter radius of the first outer peripheral surface is larger than an inscribed circle radius of a head of the hub bolt press-fitted into the bolt hole, an outer diameter radius of the second outer peripheral surface is smaller than an inscribed circle radius of the head of the hub bolt press-fitted into the bolt hole, The hub bolt has the head, a knurl portion located on one axial end side of the head and press-fitted into a bolt hole in the hub flange, and a shaft portion located on one axial end side of the knurl portion, The knurl portion is formed to have a smaller diameter than the head portion, and the shaft portion is formed to have a smaller diameter than the knurl portion, the stepped surface of the outer member has a contact portion with which the head of the hub bolt comes into contact when the hub bolt is pulled out of the bolt hole in the axial direction, the head of the hub bolt has a contacted portion that comes into contact with the contact portion of the stepped surface when the hub bolt is pulled out of the bolt hole in the axial direction, A wheel bearing device characterized in that the dimension from the other end face of the hub flange in the axial direction to the contact portion is larger than the dimension from the contacted portion of the head of the hub bolt to the one end end of the knurl portion in the axial direction.

2. The bolt hole of the hub flange has an inclined surface at the other axial end portion thereof, the diameter of which increases toward the other axial end portion, 2. The wheel bearing device according to claim 1, wherein the inclination angle of the inclined surface relative to the axial direction is 45 degrees or more.

3. 3. The wheel bearing device according to claim 1, wherein the step surface is formed by a tapered surface whose diameter increases from one end to the other end in the axial direction, or by a curved surface whose diameter increases from one end to the other end in the axial direction and which is convex or concave toward the outer diameter side.

4. A wheel bearing device as described in any one of claims 1 to 3, wherein when the shaft portion of the hub bolt is brought into contact with the inner peripheral surface on the outer diameter side of the bolt hole and the hub bolt is positioned on the outermost diameter side within the bolt hole, the outer diameter radius of the first outer peripheral surface is larger than the inscribed circle radius of the head of the hub bolt.

5. 5. The wheel bearing device according to claim 1, wherein the step surface has a forged surface or a turned surface.

6. A maintenance method for a wheel bearing device according to any one of claims 1 to 5, comprising: a knurl portion extraction process in which the hub bolt press-fitted into the bolt hole is extracted toward the other axial end until the head of the hub bolt contacts the contact portion of the stepped surface; a tilting step, which is carried out after the knurl portion pulling-out step, of tilting the hub bolt in the axial direction toward a side where the head portion is positioned radially outer than the shaft portion; a complete withdrawal step, which is carried out after the tilting step, of withdrawing the hub bolt from the bolt hole along the tilted direction in the tilting step; A maintenance method for a wheel bearing device, comprising:

7. A maintenance method for a wheel bearing device according to any one of claims 1 to 5, comprising: an insertion step of inserting the hub bolt into the bolt hole from the other axial end side with the head inclined toward the outer diameter side of the shaft portion with respect to the axial direction; an axially aligned process that is carried out after the insertion process and that moves the hub bolt to an axially aligned position; a press-fitting step, which is carried out after the axial alignment step, of press-fitting the knurl portion of the hub bolt into the bolt hole; A maintenance method for a wheel bearing device, comprising:

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