JP6855685B2 - Hub unit - Google Patents

Description

The present invention relates to a hub unit for a vehicle that rotatably supports wheels with respect to a vehicle body.

Conventionally, a hub unit that rotatably supports wheels with respect to a vehicle body has been used in various vehicles. The hub unit has an outer ring fixed to a knuckle connected to a suspension device, a hub ring having a flange to which the wheel is attached, and a plurality of rolling elements arranged between the outer ring and the hub ring. (See, for example, Patent Document 1).

In the hub unit (bearing unit) described in Patent Document 1, a brake rotor is attached together with the wheels on the attachment surface of the hub flange on the hub wheels (rotary wheels). Then, in view of the problem that brake judder is likely to occur when the runout accuracy of the mounting surface of the hub flange deteriorates, the friction between the mounting surface and the brake rotor is reduced in order to suppress the runout of the mounting surface of the hub flange. A plurality of uneven tooth profiles are formed for the purpose of forming the teeth. It is said that this tooth profile suppresses wear on the mounting surface (fretting wear), improves the runout accuracy of the mounting surface on the hub flange, and suppresses brake judder.

Japanese Unexamined Patent Publication No. 2008-114770

In the hub unit described in Patent Document 1, it is assumed that the tooth profile portion of the hub flange is formed by forging or cutting. When the tooth profile portion is formed by forging, the material flow pressure is concentrated on the corner portion corresponding to the tooth profile portion in the forging die during forging, which shortens the life of the forging die and increases the manufacturing cost. On the other hand, even when the tooth profile is formed by cutting, the tooth profile is formed by cutting the mounting surface after forming the hub flange by forging or the like, which increases the number of cutting processes in the manufacturing process. The cost is high.

Therefore, an object of the present invention is to provide a hub unit capable of suppressing runout of a flange of a hub wheel without increasing the manufacturing cost.

In order to achieve the above object, the present invention has an outer ring fixed to a support member on the vehicle body side, a hub ring having a disk-shaped wheel mounting flange on which the wheel is mounted, and between the outer ring and the hub ring. A plurality of arranged rolling elements and a plurality of hub bolts press-fitted into each of the plurality of bolt insertion holes formed in the wheel mounting flange are provided, and the wheel is attached to the wheel mounting flange by the plurality of hub bolts. The wheel mounting flange of the hub unit has a thick portion and a thin portion having different thicknesses from the mounting surface on which the wheel is mounted, and the bolt insertion hole is formed in the thick portion to form the wheel. When the mounting flange is viewed from the side opposite to the mounting surface, the outer edge of the thick portion is formed on the outer peripheral edge of the wheel mounting flange within the range where the bolt insertion hole is formed, and the wheel mounting flange is formed. Between the pair of the bolt insertion holes adjacent to each other in the circumferential direction of the wheel, the wheels extend in the direction along the line parallel to the straight line, radially outward from the straight line connecting the bolt hole centers of the bolt insertion holes. At the boundary between the range in which the bolt insertion hole is formed and the pair of the bolt insertion holes adjacent to each other in the circumferential direction of the wheel mounting flange, the center of the bolt hole and the hub wheel are formed. When the wheel mounting flange is extended in a direction parallel to a straight line connecting the axis and the wheel mounting flange is viewed from the side opposite to the mounting surface, the outer edge of the thick portion is the wheel mounting. Provided is a hub unit formed between a pair of bolt insertion holes adjacent to each other in the circumferential direction of a flange in a radial direction with respect to a straight line connecting the maximum outer diameter portions of the bolt insertion holes.

According to the hub unit according to the present invention, it is possible to suppress runout of the flange of the hub wheel without increasing the manufacturing cost.

It is sectional drawing which shows the whole structure of the hub unit which concerns on embodiment of this invention. The hub ring of the hub unit is shown, (a) is a plan view, and (b) is a side view. (A) is an explanatory view showing the amount of displacement of each part of the wheel mounting flange before and after the hub bolt is press-fitted into the bolt insertion hole. (B) is a graph showing the displacement amount of the wheel mounting flange. A hub ring according to a comparative example is shown, (a) is a plan view, and (b) is a side view. (A) is an explanatory view showing the amount of displacement of each part of the wheel mounting flange before and after the hub bolt is press-fitted into the bolt insertion hole of the hub wheel according to the comparative example. (B) is a graph showing the displacement amount of the wheel mounting flange according to the comparative example.

[Embodiment]
Embodiments of the present invention will be described with reference to FIGS. 1 to 3. The embodiments described below are shown as suitable specific examples for carrying out the present invention. Therefore, although there are some parts that specifically exemplify various technically preferable technical matters, the technical scope of the present invention is not limited to this specific aspect.

FIG. 1 is a cross-sectional view showing an overall configuration of a hub unit according to an embodiment of the present invention. In FIG. 1, a hub unit mounted on a vehicle is shown together with its peripheral portion. 2A and 2B show hub wheels of a hub unit, where FIG. 2A is a plan view and FIG. 2B is a side view.

The hub unit 1 rotatably supports the wheels 91 together with the brake rotor 92 with respect to the knuckle 90 as a support member on the vehicle body side connected to the suspension device of the vehicle. FIG. 1 shows a part of the wheel of the wheel 91 and the brake rotor 92. Hereinafter, in the hub unit 1, the side on which the wheel 91 is attached (left side in FIG. 1) is referred to as the vehicle outer side, and the opposite side (right side in FIG. 1) is referred to as the vehicle inner side.

The hub unit 1 is fitted to the outer ring 2 fixed to the knuckle 90, the hub wheel 3 having a disk-shaped wheel mounting flange 31 to which the wheel 91 and the brake rotor 92 are attached, and the hub wheel 3 inside the outer ring 2. The inner ring 4, the plurality of rolling elements 5 arranged between the outer ring 2, the hub ring 3, and the inner ring 4, the cages 61 and 62 for holding the plurality of rolling elements 5, and the sealing members 71 and 72. A plurality of hub bolts 8 fixed to the wheel mounting flange 31 by press fitting are provided. The hub ring 3 and the inner ring 4 can rotate with respect to the outer ring 2 about the rotation axis O by the rolling of the rolling element 5. FIG. 1 shows the hub ring 3 in the cross section taken along the line AA of FIG. 2 (a).

The outer ring 2 integrally has a tubular tubular portion 21 and a fixed flange 22 that protrudes outward from the tubular portion 21 and is fixed to the knuckle 90. Seal members 71 and 72 are arranged between both ends of the tubular portion 21 and the hub ring 3 and the inner ring 4. A first outer raceway surface 2a and a second outer raceway surface 2b on which the rolling element 5 rolls are formed parallel to each other on the inner circumference of the tubular portion 21. The fixing flange 22 is fixed to the knuckle 90 by a plurality of bolts 93. In FIG. 1, one of the bolts 93 is illustrated. The bolt 93 is screwed into the screw hole 900 formed in the knuckle 90 by inserting the insertion hole 220 formed in the fixed flange 22.

The hub wheel 3 has a wheel mounting flange 31, a body portion 33 arranged inside the outer ring 2, a connecting portion 32 connecting the wheel mounting flange 31 and the body portion 33, and the wheel mounting flange 31 to the vehicle outer side. It integrally has a protruding cylindrical boss portion 34. The hub wheel 3 is made of, for example, S55C (carbon steel for machine structure) and is formed by forging. The wheels 91 and the brake rotor 92 are fitted onto the boss portion 34 so that the wheels 91 and the brake rotor 92 are positioned in the radial direction with respect to the hub wheel 3.

The body portion 33 has a large diameter portion 331 on the vehicle outer side and a small diameter portion 332 of the vehicle inner. An inner raceway surface 3a facing the first outer raceway surface 2a of the outer ring 2 is formed on the outer peripheral surface of the large diameter portion 331. An inner ring 4 is fitted on the outer peripheral surface of the small diameter portion 332. An inner raceway surface 4a facing the second outer raceway surface 2b of the outer ring 2 is formed on the outer peripheral surface of the inner ring 4. The inner ring 4 is fixed to the hub wheel 3 by a crimping portion 333 that is plastically deformed at the end portion of the body portion 33 of the hub wheel 3 on the vehicle inner side. A plurality of rolling elements 5 are arranged between the first outer raceway surface 2a and the inner raceway surface 3a of the hub ring 3, and between the second outer raceway surface 2b and the inner raceway surface 4a of the inner ring 4. Has been done.

The wheel mounting flange 31 is formed with a plurality of bolt insertion holes 310 into which the hub bolt 8 is press-fitted. In the present embodiment, five bolt insertion holes 310 are formed in the wheel mounting flange 31 at equal intervals along the circumferential direction, and hub bolts 8 are press-fitted into the respective bolt insertion holes 310. The wheel 91 and the brake rotor 92 are fixed to the wheel mounting flange 31 by the hub bolt 8 and the wheel nut 94 screwed into the hub bolt 8.

The hub bolt 8 integrally has a head portion 81 and a shaft portion 82. The head 81 is in contact with the end surface of the wheel mounting flange 31 on the vehicle inner side. The shaft portion 82 is press-fitted into the bolt insertion hole 310 of the wheel mounting flange 31, and is inserted into the insertion hole 910 formed in the wheel of the wheel 91 and the insertion hole 920 formed in the brake rotor 92. The shaft portion 82 has a base end portion press-fitted into the bolt insertion hole 310 of the wheel mounting flange 31 as a serration portion 821 having a plurality of irregularities on the outer peripheral surface. The inner diameter of the bolt insertion hole 310 is set to a dimension in which the serration portion 821 is press-fitted with a predetermined tightening allowance (for example, 0.36 mm). A male screw portion 822 into which the wheel nut 94 is screwed is formed at the tip end portion of the shaft portion 82.

In the present embodiment, the rolling element 5 is a sphere, but the rolling element 5 is not limited to this and may be a conical roller. Further, in the present embodiment, one inner ring 4 is fitted on the outer circumference of the body 33 of the hub ring 3, but a pair of inner rings are fitted on the body 33, and the rolling elements 5 are attached to the respective inner rings. An inner raceway surface to be rolled may be formed. In this case, a plurality of rolling elements 5 are arranged between the outer ring 2 and the hub ring 3 via a pair of inner rings.

The wheel mounting flange 31 has a thick portion 311 and a thin portion 312 having different thicknesses from the mounting surface 31a on which the wheel 91 and the brake rotor 92 are mounted. Since the wheel mounting flange 31 is provided with the thin-walled portion 312, the weight of the hub wheel 3 is reduced. The bolt insertion hole 310 is formed in the thick portion 311. The mounting surface 31a is a flat surface perpendicular to the rotation axis O. The thickness of the thin portion 312 in the axial direction parallel to the rotation axis O is, for example, 30 to 70% of the thickness of the thick portion 311 in the same direction.

In the present embodiment, the inner side surface 312a (the end surface of the thin-walled portion 312 on the vehicle inner side) opposite to the mounting surface 31a is a flat surface parallel to the mounting surface 31a. However, the thickness of the thin portion 312 may be thinner toward the outer diameter side so that the inner side surface 312a approaches the mounting surface 31a toward the outer diameter side of the wheel mounting flange 31. The thick portion 311 on the vehicle inner side of the inner side surface 312a of the thin portion 312 is formed as a build-up portion, and the rigidity of the wheel mounting flange 31 is increased by this build-up portion.

FIG. 2A shows a state in which the wheel mounting flange 31 is viewed from the side opposite to the mounting surface 31a. In FIG. 2A, the bolt hole centers of the bolt insertion holes 310 are indicated by reference numerals 310a, and a polygon P formed by connecting these bolt hole centers 310a with a straight line is shown. In the present embodiment, since the wheel mounting flange 31 is formed with five bolt insertion holes 310, the polygon P is a regular pentagon. The thick portion 311 projects toward the outer diameter side of the wheel mounting flange 31 at five points in the circumferential direction so as to include a peripheral portion of the bolt insertion hole 310 with which the head 81 of the hub bolt 8 abuts. The thin-walled portion 312 is provided between each of the thick-walled portions 311 of the portion protruding toward the outer diameter side.

As shown in FIG. 2A, the outer edge of the thick portion 311 is wheel-mounted in the range where the bolt insertion hole 310 is formed, that is, in the range outside the bolt insertion hole 310 in the radial direction of the wheel mounting flange 31. It is formed on the outer peripheral edge of the flange 31. Further, the outer edge of the thick portion 311 is radially outward from the straight line connecting the bolt hole centers 310a of the respective bolt insertion holes 310 between the pair of bolt insertion holes 310 adjacent to each other in the circumferential direction of the wheel mounting flange 31. Is formed in. In other words, each side of the polygon P is included in the thick portion 311 and does not intersect with the thin portion 312.

As described above, the hub bolt 8 is press-fitted into the bolt insertion hole 310 with a predetermined tightening allowance. Therefore, when the hub bolt 8 is press-fitted into the bolt insertion hole 310, stress is generated in the wheel mounting flange 31, and the stress causes the wheel mounting flange 31 to be deformed. It has been confirmed by the present inventor that this deformation is in the direction in which the outer peripheral end of the wheel mounting flange 31 is directed toward the vehicle inner side.

In FIG. 3 (a), illustrates the amount of displacement of each portion of the wheel mounting flange 31 before and after the respective bolt insertion holes 310 press-fitting the hub bolts 8 at 5 stages of the first to fifth regions A ₁ to A _5. The first area A ₁ is the largest area is the amount of displacement of the vehicle inner side after press-fitting the hub bolts 8, the fifth region A ₅ represents the displacement amount of the vehicle inner side is the smallest area. The second region A ₂ , the third region A ₃ , and the fourth region A ₄ are intermediate regions in which the amount of displacement toward the vehicle inner side gradually decreases in this order.

As shown in FIG. 3A, the amount of displacement due to press-fitting the hub bolt 8 is the largest on the outside of the bolt insertion hole 310 in the radial direction of the wheel mounting flange 31, and the smallest on the inside of the bolt insertion hole 310. The thin portion 312 is largely contained in the third region A _3, only a portion close to the midpoint of each side of the polygon P is included in the fourth area A ₄ relatively displacement amount is small. However, the fourth region A ₄ in the thin portion 312 does not reach the outer peripheral edge of the wheel mounting flange 31.

FIG. 3B is a graph showing the amount of displacement of the wheel mounting flange 31 at each portion of the annular measurement position C shown by the broken line in FIG. 3A. The measurement position C is set at the outer peripheral edge of the mounting surface 31a on the wheel mounting flange 31. In this graph, the position corresponding to the outer circumference of the bolt hole center 310a of one bolt insertion hole 310 is set as the starting point S (phase = 0 °), and the displacement amount of each portion is shown clockwise from the starting point S.

As shown in FIG. 3B, the amount of displacement of the wheel mounting flange 31 increases at a portion corresponding to the outer periphery of each bolt insertion hole 310. Further, at a position corresponding to the pair of bolt insertion holes 310 adjacent to each other in the circumferential direction, a maximum point having a displacement amount smaller than the displacement amount at the position corresponding to the outer periphery of the bolt insertion hole 310 appears.

The reason why the displacement amount of the wheel mounting flange 31 is large at the portion corresponding to the outer periphery of each bolt insertion hole 310 is that the portion on the vehicle outer side of the inner side surface 312a of the thin wall portion 312 is on the vehicle inner side of the inner side surface 312a. It is considered that a larger stress is generated because the rigidity is higher than that of the portion of the above, and the portion on the vehicle inner side of the inner side surface 312a is curved by this stress. The reason why the rigidity of the wheel mounting flange 31 is higher on the vehicle outer side than the inner side surface 312a of the thin portion 312 is that a pair of bolt insertion holes 310 adjacent to each other in the circumferential direction are formed on the vehicle inner side portion than the inner side surface 312a. This is because there is an area where the meat (material) is not piled up between the two.

Further, the reason why the maximum point of the displacement amount appears at the position between the pair of bolt insertion holes 310 adjacent to each other in the circumferential direction is that the thin portion 312 does not exist on the straight line connecting the bolt hole centers 310a of both bolt insertion holes 310. Therefore, it is considered that a large compressive stress is generated at the portion sandwiched between the bolt insertion holes 310, and this compressive stress also affects the outer peripheral end portion of the thin wall portion 312 having relatively low rigidity.

(Comparison example)
Next, the hub wheel 3A according to the comparative example will be described with reference to FIGS. 4 and 5.

4A and 4B show a hub ring 3A according to a comparative example, where FIG. 4A is a plan view and FIG. 4B is a side view. 5 (a) is, FIG amount of displacement of the respective portions of the front and rear wheel mounting flange 31A press-fitting the hub bolts 8 into the bolt insertion holes 310 of the hub 3A in five stages of the first to fifth regions _A 1 to A ₅ Shown. FIG. 5B is a graph showing the amount of displacement of the wheel mounting flange 31A at each portion of the annular measurement position C shown by the broken line in FIG. 5A. In FIGS. 4 and 5, the components common to the hub wheel 3 according to the embodiment described with reference to FIGS. 1 to 3 are designated by the same reference numerals and duplicated description will be omitted.

The hub wheel 3A according to the comparative example has a different shape of the wheel mounting flange 31A from the hub wheel 3 according to the embodiment shown in FIGS. 2 and 3. More specifically, the wheel mounting flange 31A has a thick-walled portion 311A and a thin-walled portion 312A, similarly to the wheel mounting flange 31 of the hub wheel 3, but the shape of the thick-walled portion 311A is different. There is.

The outer diameter dimension and weight of the hub wheel 3A are the same as those of the hub wheel 3 according to the embodiment. Further, the thickness of the thick portion 311A and the thin portion 312A is also the same as the thickness of the thick portion 311 and the thin portion 312 of the wheel mounting flange 31 according to the embodiment. Furthermore, the _{displacement amounts of the first to} fifth regions A 1 to A ₅ and the size of one scale on the vertical axis of the graph shown in FIG. 5 (b) are also referred to with reference to FIGS. 3 (a) and 3 (b). It is the same as the one explained in.

In the hub ring 3A, the outer edge of the thick portion 311A intersects each side of the polygon P formed by connecting the bolt hole centers 310a of the five bolt insertion holes 310 with a straight line. That is, a part of the thin portion 312A is formed inside the polygon P. Further, the hub wheel 3A, the fourth region _{A 4} in the thin part 312A, and reaches the outer peripheral edge of the wheel mounting flange 31A.

As shown in FIG. 5B, the displacement amount of the wheel mounting flange 31A increases at a portion corresponding to the outer periphery of each bolt insertion hole 310, similarly to the wheel mounting flange 31 according to the embodiment. However, the maximum point does not appear at the position between the pair of bolt insertion holes 310 adjacent to each other in the circumferential direction. The reason for this is that the thin-walled portion 312 having a lower rigidity than the thick-walled portion 311 exists on the straight line connecting the bolt hole centers 310a of the two bolt insertion holes 310 adjacent to each other in the circumferential direction. It is considered that the compressive stress of the sandwiched portion is relaxed, and the influence of this compressive stress on the outer peripheral end portion of the thin portion 312 is reduced.

In the hub wheel 3A according to this comparative example, as shown in FIG. 5B, the difference between the maximum value and the minimum value of the displacement amount of the wheel mounting flange 31A is large. That is, the swing width of the axial position on the outer peripheral edge of the mounting surface 31a of the wheel mounting flange 31A is large. Therefore, vibration and brake judder are likely to occur when the vehicle running in which the wheels 91 and the brake rotor 92 mounted on the wheel mounting flange 31A rotate.

On the other hand, in the hub wheel 3 according to the embodiment, as is clear from the comparison between FIGS. 3 (b) and 5 (b), the average value of the displacement amount of the wheel mounting flange 31 before and after the hub bolt 8 is press-fitted is , Larger than the hub wheel 3A according to the comparative example. However, the difference between the maximum value and the minimum value of the displacement amount is smaller than that of the hub wheel 3A. Therefore, the swing width of the axial position at the outer peripheral edge of the mounting surface 31a of the wheel mounting flange 31 is reduced, the mounting rigidity of the wheels 91 and the brake rotor 92 is increased, and vibration and brake judder during vehicle running are suppressed. The wheel.

(Effect of embodiment)
According to the present embodiment described above, the runout of the wheel mounting flange 31 can be suppressed without cutting or the like on the mounting surface 31a of the wheel mounting flange 31 of the hub wheel 3. That is, since the thick portion 311 having a shape as illustrated in FIG. 2 can be easily formed by forging, it is possible to suppress the runout of the wheel mounting flange 31 without increasing the manufacturing cost. ..

(Additional note)
Although the present invention has been described above based on the embodiment, the above-described embodiment does not limit the invention according to the claims. It should also be noted that not all combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

In addition, the present invention can be appropriately modified and implemented without departing from the spirit of the present invention. For example, in the above embodiment, the hub unit 1 that supports the wheel 91 as a driven wheel to which the driving force of a driving source such as an engine is not transmitted has been described as an example. However, the present invention is not limited to this, and the present invention can be applied to a hub unit that supports a driving wheel to which a driving force is transmitted.

1 ... Hub unit 2 ... Outer ring 3,3A ... Hub wheel 31,31A ... Wheel mounting flange 31a ... Mounting surface 310 ... Bolt insertion hole 310a ... Bolt hole center 311, 311A ... Thick part 312, 312A ... Thin part 5 ... Rolling Moving body 8 ... Hub bolt 91 ... Wheel

Claims (1)

An outer ring fixed to a support member on the vehicle body side, a hub ring having a disk-shaped wheel mounting flange on which the wheel is mounted, a plurality of rolling elements arranged between the outer ring and the hub wheel, and the wheel mounting. A hub unit including a plurality of hub bolts press-fitted into each of a plurality of bolt insertion holes formed in a flange, and the wheels are mounted on the wheel mounting flange by the plurality of hub bolts.
The wheel mounting flange has a thick portion and a thin portion having different thicknesses from the mounting surface on which the wheel is mounted, and the bolt insertion hole is formed in the thick portion.
When the wheel mounting flange is viewed from the side opposite to the mounting surface, the outer edge of the thick portion is formed on the outer peripheral edge of the wheel mounting flange in the range where the bolt insertion hole is formed, and the wheel. Between the pair of bolt insertion holes adjacent to each other in the circumferential direction of the mounting flange, radially outward from the straight line connecting the bolt hole centers of the respective bolt insertion holes, in the direction along the line parallel to the straight line. At the boundary between the range in which the bolt insertion holes are formed by stretching and the pair of bolt insertion holes adjacent to each other in the circumferential direction of the wheel mounting flange, the center of the bolt holes and the hub It extends in the direction along the line parallel to the straight line connecting the axis of the ring .
When the wheel mounting flange is viewed from the side opposite to the mounting surface, the outer edge of the thick portion is formed between the pair of bolt insertion holes adjacent to each other in the circumferential direction of the wheel mounting flange. It is formed radially outward from the straight line connecting the maximum outer diameter points of the bolt insertion holes.
Hub unit.

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