JP7754753B2 - Wheel bearing device - Google Patents

Description

The present invention relates to a wheel bearing device.

Wheel bearing devices that support the wheels of automobiles and other vehicles for free rotation are known. Wheel bearing devices have a hub flange that extends radially outward from the hub ring, which is the inner member. Hub bolts are press-fit into bolt holes formed in the hub flange to fasten the hub ring to the wheel or other vehicle.

When designing the internal specifications of a wheel bearing assembly, increasing the pitch circle diameter (P.C.D.) and ball diameter of the balls housed between the raceway grooves 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 the outer raceway groove of the outer member, it is necessary to ensure a certain thickness between the bottom of the outer raceway groove and the outer peripheral surface of the outer member.

Increasing the pitch circle diameter or ball diameter of the balls or increasing the thickness of the outer member in this way increases the outer diameter of the outer surface of the outer member. This means that when attempting to remove a hub bolt press-fitted into the hub flange, interference between the hub flange and the outer surface of the outer member could prevent the hub bolt from being removed, potentially reducing the maintainability of the wheel bearing assembly.

To solve this problem, Patent Document 1 discloses a wheel bearing device in which a guide groove is formed on the outer diameter of the thick-walled portion at the outer end of the outer ring, which serves as the outer member, to guide the hub bolt along the rotation axis.

Patent No. 6725993

However, forming a guide groove on the outer diameter portion of the outer ring, as in the wheel bearing device disclosed in Patent Document 1, restricts the outer diameter dimension of the outer ring where the guide groove is formed, which can restrict the design of internal specifications such as the ball pitch circle diameter and ball diameter, and makes it difficult to ensure the outer ring's thickness, potentially making it impossible to design a wheel bearing device with sufficient durability. This problem is particularly pronounced in wheel bearing devices in which the hub bolts are located on the inner diameter side in order to make them more compact.

The present invention was made in light of the above circumstances, and aims to provide a wheel bearing device that improves maintainability while minimizing constraints on the design of internal specifications.

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, an inner member having double-row inner raceway grooves facing the double-row outer raceway grooves, and a hub flange extending radially outward at one axial end, 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, and 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 that is located axially closer to the hub flange than the first outer peripheral surface and has a smaller diameter than the first outer peripheral surface; and a stepped surface that is located axially between the first and second outer peripheral surfaces and connects the first and second outer peripheral surfaces, wherein the outer radius of the first outer peripheral surface is larger than the inscribed circle radius of the head of the hub bolt press-fitted 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 press-fitted into the bolt hole.

This invention improves the maintainability of wheel bearing devices while minimizing restrictions on the design of the internal specifications of the wheel bearing device.

1 is a side cross-sectional view showing a wheel bearing device. FIG. 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. 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. 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. 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. FIG. 10 is a side cross-sectional view showing the inclined surface of the bolt hole. 10A to 10C are diagrams showing the procedure for removing the hub bolt from the bolt hole. 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. 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. 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. 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. 10A to 10C are diagrams illustrating a procedure for press-fitting a hub bolt into a bolt hole.

The following describes an embodiment of the present invention with reference to the accompanying drawings.

[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 is used to rotatably support a wheel in a suspension system of a vehicle such as an automobile.

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

In the following description, the axial direction refers to the direction along the rotational axis X of the wheel support bearing device 1. Additionally, 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.

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

The inner seal member 10 is fitted into the inner opening 21, thereby closing the inner opening end of the annular space S formed by the outer ring 2 (the outer member) and the hub ring 3 and inner ring 4 (the inner members). The outer seal member 9 is fitted into the outer opening 22, thereby closing the outer opening end of the annular space S.

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 interior of the wheel bearing device 1.

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

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 integrally formed at the outer end of the hub wheel 3. The wheel mounting flange 32 is an example of a hub flange. Multiple bolt holes 35 are formed in the wheel mounting flange 32. Hub bolts 36 can be press-fitted into the bolt holes 35 to fasten the hub wheel 3 to a wheel or brake component.

The hub wheel 3 has a sliding surface 34 formed on the base side of the wheel mounting flange 32, against which the outer seal member 9 slides. The outer peripheral surface of the hub wheel 3 is provided with an outer inner raceway groove 33 that faces the outer outer raceway groove 24 on the outer side of the outer ring 2. In other words, the hub wheel 3 defines the inner raceway groove 33 on the outer side of the inner member.

The inner ring 4 is mounted 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 formed on the outer peripheral surface of the inner ring 4 so as to face the outer raceway groove 23 on the inner side of the outer ring 2. In other words, the inner ring 4 forms the inner raceway groove 41 on the inner side of the inner member.

The inner ball row 5 and outer ball row 6, which are rolling rows, are composed of a plurality of balls 7, which serve as rolling elements, 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 outer ball row 6 are rollably housed between the raceway grooves of the outer member and the inner member.

In the wheel bearing device 1, the outer ring 2, hub ring 3, inner ring 4, inner ball row 5, and outer ball row 6 form a double-row angular ball bearing. Note that the wheel bearing device 1 may also be configured as a double-row tapered roller bearing instead of a double-row angular ball bearing.

[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.

The knurl portion 362 is press-fit into the bolt hole 35 of the hub bolt 36, and has multiple axially extending knurls formed circumferentially. 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.

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 press-fitted into the bolt hole 35, the hub wheel 3 can be fastened to the wheel or brake component.

As shown in Figure 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.

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 radial length between the point on the head 361 closest to the rotation axis X and the rotation axis X. In other words, the inscribed circle radius R0 is the radius of a circle centered on the rotation axis X and tangent to the point on the head 361 closest to the rotation axis X.

[Outer ring]
As shown in Figure 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 (P.C.D.) and diameter of the balls 7.

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.

The outer ring 2 has a radial thickness d between the bottom 24a and the first outer peripheral surface 27. The thickness d is determined, for example, taking into account the dimensions necessary to prevent hardening when induction hardening the outer raceway groove 24. The outer radius of the first outer peripheral surface 27 from the rotation axis X is the outer radius R2. The outer radius R2 can be set to at least the inner radius R1 of the bottom 24a plus the thickness d of the outer ring 2.

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 outer radius R3. The outer radius R3 is formed to be smaller than the outer radius R2 of the first outer peripheral surface 27.

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. The inner end of the step surface 29 is connected to the first outer peripheral surface 27, and the outer end of the step surface 29 is connected to the second outer peripheral surface 28.

Step surface 29 is formed by a tapered surface that linearly increases in diameter from the outer end to the inner end. However, 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, as in step surface 29A shown in Figure 4. 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, as in step surface 29B shown in Figure 5.

In this way, by making it possible to form the 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, it is possible to increase the degree of freedom when designing the external shape of the outer ring 2.

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 turning the outer peripheral surface of the outer ring 2 after the outer ring 2 is formed by forging. 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.

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, there is no need to turn the first outer peripheral surface 27, the second outer peripheral surface 28, and the stepped surface 29, simplifying 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 shape 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.

The outer diameter radius R2 of the first outer surface 27 is 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 R3 of the second outer surface 28 is 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).

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, but because the outer diameter radius R3 of the second outer peripheral surface 28 is smaller than the inscribed circle radius R0 of the head 361, 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 spaced apart in the radial direction and do not interfere with each other.

On the other hand, as shown in FIG. 6 , the outer diameter radius dimension R2 of the first outer 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. Therefore, 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 that comes into contact with the head 361 of the hub bolt 36 when the hub bolt 36 press-fitted into the bolt hole 35 is pulled out axially from the bolt hole 35.

As shown in Figures 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 from the bolt hole 35 toward the inner side. In the hub bolt 36, the axial dimension from the contacted portion 361a of the head 361 to the outer end 362a of the knurl portion 362 is L1.

As shown in Figure 6, in the wheel bearing assembly 1, the axial dimension from the inner end surface 321 of the wheel mounting flange 32 to the contact portion 291 is L2. Dimension L2 is larger than dimension L1 of the hub bolt 36 (L2 > L1).

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

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

If guide grooves for guiding the hub bolts 36 were formed on the outer peripheral surface of the outer ring 2, the circumferential shape of the outer peripheral surface would become complex, which could reduce the lifespan of the forging die used to forge the outer ring 2. However, the outer peripheral surface of the outer ring 2 does not have guide grooves for guiding the hub bolts 36, and the circumferential shape of the outer peripheral surface is not complex, so it is possible to prevent a reduction in the lifespan of the forging die.

[Method for maintaining wheel bearing device]
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.

(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.

When removing the hub bolt 36 press-fitted into the bolt hole 35, the knurl removal step S01 is first carried out, as shown in Figure 8.

As shown in Figure 6, in the knurl extraction process 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 362, so the knurl 362 of the hub bolt 36 is completely extracted from the bolt hole 35.

After the knurl extraction step S01 is performed, the shaft 363 of the hub bolt 36 is positioned within the bolt hole 35. Because the shaft 363 has an outer diameter D3 that is smaller than the outer diameter D2 of the knurl 362, a gap exists between the outer surface of the shaft 363 and the inner surface of the bolt hole 35.

After the knurl extraction step S01, the parallel movement step S02 is carried out. As shown in Figure 9, in the parallel movement step S02, the hub bolt 36 is translated outward until the outer surface of the shaft 363 contacts the inner surface of the bolt hole 35. By translating the hub bolt 36 outward, a gap is created between the head 361 and the contact portion 291 of the stepped surface 29, allowing the hub bolt 36 to be moved further inward.

Even when the shaft 363 of the hub bolt 36 is in contact with the inner peripheral surface of the outer diameter side of the bolt hole 35 and the hub bolt 36 is positioned at the outermost diameter side within the bolt hole 35, the outer radius 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.

The parallel movement step S02 is followed by the additional withdrawal step S03. As shown in Figure 10, in the additional withdrawal step S03, the hub bolt 36, which was translated toward the outer diameter side in the parallel movement step S02, is further withdrawn axially toward the inner side 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.

In other words, by positioning the hub bolt 36 on the outermost side within the bolt hole 35, it can be pulled further inward from the position after performing the knurl removal step S01. However, because 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 on the outermost side within the bolt hole 35, the head 361 abuts against the step surface 29.

In this way, in the additional extraction step S03, the knurl portion 362 that has been extracted from the bolt hole 35 can be moved to a position further away from the bolt hole 35 toward the inner side.

After the additional extraction step S03, the tilting step S04 is carried out. As shown in Figure 11, in the tilting step S04, the hub bolt 36 is tilted axially so that the head 361 is positioned further outward than the shaft portion 363.

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 outward from the outer circumferential surface of the outer ring 2.

After the tilting step S04, the full withdrawal step S05 is carried out. As shown in Figure 12, in the full withdrawal step S05, the hub bolt 36 is pulled out of the bolt hole 35 in the direction of tilting in the tilting step S04. In this case, the hub bolt 36 is pulled out until the male thread portion 364 is completely removed from the bolt hole 35.

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 surface of the outer ring 2. Therefore, even if the outer diameter radius 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, it is possible to completely withdraw the hub bolt 36 from the bolt hole 35.

In addition, in the wheel support bearing device 1, even if the outer diameter radius dimension R2 of the first outer peripheral surface 27 is 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 the location corresponding to the outer raceway groove 24 on the outer side, by forming a second outer peripheral surface 28 with a smaller diameter than the first outer peripheral surface 27 and a step surface 29 connecting the first outer peripheral surface 27 and the second outer peripheral surface 28, it is still possible to completely withdraw the hub bolt 36 from the bolt hole 35. This reduces constraints on the design of the internal specifications of the wheel support bearing device 1, while improving the maintainability of the wheel support bearing device 1.

In particular, in the wheel bearing device 1, the dimension L2 from the inner end surface 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. Therefore, 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 of 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 process of pulling out the hub bolt 36.

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

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

In addition, in this embodiment, the step surface 29 is formed as a tapered surface that linearly expands in diameter. However, 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, facilitating the operation of pulling out the hub bolt 36.

Furthermore, if the dimension L2 from the inner end surface 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, the hub bolt 36 can be pulled further inward in the knurl portion extraction step S01. This makes it possible to easily tilt the hub bolt 36 axially, so that the tilting step S04 can be performed after the knurl portion extraction step S01 without going through the translation step S02 and additional extraction step S03.

(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.

As shown in Figure 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 outer diameter side of the shank 363. As shown in Figure 11, in the insertion step S11, the hub bolt 36 is inserted until the shank 363 enters the bolt hole 35.

After the insertion step S11, the axial alignment step S12 is carried out. As shown in Figure 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. Then, as shown in Figure 9, the hub bolt 36 is moved axially outward until the outer end 362a of the knurl portion 362 is positioned near the inner end face 321 of the wheel mounting flange 32.

After the axial alignment step S12, the parallel movement step S13 is carried out. 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 and the center of the bolt hole 35 are aligned. 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.

After the parallel movement step S13, the press-fitting step S14 is carried out. 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.

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 relative to the shaft 363, and then moving the hub bolt 36 to an axial position and press-fitting it into the bolt hole 35, it becomes possible to press-fit the hub bolt 36 into the bolt hole 35 even if the outer diameter radius dimension R2 of the first outer peripheral 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.

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 tilted relative to the axial direction in the axial movement step S12, to a position along the axial direction, 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 are aligned, thereby making it possible to skip the parallel movement step S13 and proceed to the press-fit step S14.

Although the embodiments of the present invention have been described above, the present invention is in no way limited to these embodiments, which are merely illustrative, and it goes without saying that the present invention can be embodied in a variety of 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, as well as all modifications within the scope of the claims.

REFERENCE SIGNS LIST 1 Wheel bearing device 2 Outer ring 3 Hub ring 4 Inner ring 5 Inner-side ball row 6 Outer-side ball row 23 (Inner-side) outer raceway groove 24 (Outer-side) outer raceway groove 24a Bottom 27 First outer peripheral surface 28 Second outer peripheral surface 29 Step surface 32 Wheel mounting flange 33 (Outer-side) inner raceway groove 35 Bolt hole 36 Hub bolt 41 (Inner-side) inner raceway groove 291 Contact portion 321 Inner-side end face 351 Inclined surface 361 Head 361a Contacted portion 362 Knurled portion 362a Outer-side end portion 363 Shaft portion D1 Outer diameter (of head) D2 Outer diameter (of knurled portion) D3 Outer diameter (of shaft portion) L1 Dimension (from contacted portion of head to outer-side end of knurled portion) L2 R0: Dimension (from the inner end face of the wheel mounting flange to the contact part) R2: Outer diameter radius dimension (of the first outer surface) R3: Outer diameter radius dimension (of the second outer surface) R4: Inscribed circle radius (when the shank of the hub bolt is in contact with the inner circumferential surface on the outer diameter side of the bolt hole) S01: Knurl part extraction process S04: Tilt process S05: Complete extraction process S11: Insertion process S12: Along-axis process S14: Press-fit process θ: Tilt angle

Claims (7)

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