JP2008013072A - Axle structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide axle structure capable of maintaining high run out accuracy of a hub flange after starting to use, coping with deterioration of run out of the hub flange due to aging effect, and eliminating an influence of the heat of a brake rotor. <P>SOLUTION: The periphery of a hub bolt hole of the hub flange 5 for fitting a brake rotor 30 and a wheel 40 is machined into a soft facing part 51, and a part of the brake rotor 30 corresponding to the periphery of the hub bolt hole in the opposite surface to the hub flange 5 is machined to be formed into a protecting part 52. Height dimension of the projecting part 52 is set larger than depth dimension of the soft facing part 51. With this structure, when the projecting part 52 formed in the opposite surface of the brake rotor 30 is inserted into the soft facing part 51 of the hub flange 5, a clearance is formed between the surface of the hub flange 5 and the opposite surface of the brake rotor 30. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an axle structure capable of taking measures against hub flange run-out deterioration and reducing the influence of heat generated by a brake rotor.

  Disc brakes with excellent braking power have been popular, especially in front wheels. When braking by holding a disc brake rotor between brake pads, a vibration noise phenomenon called a brake judder may occur particularly in a speed range of 60 to 100 km.

  Recently, the technology for improving the ride comfort of the vehicle itself has evolved, and the vehicle has become low noise and low vibration. As a result, the brake judder has become relatively conspicuous, and countermeasures have become a major technical issue.

  Although the generation mechanism of the brake judder has not been completely analyzed, it has been found that an effective measure is to improve the deflection accuracy of the brake rotor surface.

  In order to improve the runout accuracy of the brake rotor surface, methods such as secondary machining of the brake rotor surface after assembly of the axle assembly have been taken for some time, but the complex shape of the axle assembly remains unchanged. Secondary processing requires special equipment.

  In addition, because the brake rotor and tire are assembled to the hub flange with the same hub bolt, when replacing the tire, the brake rotor is also unfastened, and the phase difference during reassembly As a result, the hub flange runout accuracy deteriorates.

  Therefore, recently, even if the brake rotor and the hub flange are assembled at random, the runout accuracy has been regulated so that the necessary runout accuracy of the hub flange can be obtained.

  Therefore, even in a wheel bearing unit in which a hub flange is integrated with a bearing, improvement in hub flange runout accuracy has been required.

  FIG. 5 is a longitudinal sectional view of an axle structure according to a conventional example. The axle structure includes an inner member 1, an outer member 10, and double-row rolling elements 20 and 20.

  The inner member 1 includes a hub 2 and a separate inner ring 3, and the inner ring 3 is press-fitted into a stepped portion 4 formed at an inboard side end of the hub 2.

  Further, an outboard side raceway surface 2 a is formed on the outer periphery of the hub 2, and an inboard side raceway surface 3 a is formed on the outer periphery of the inner ring 3. Further, the hub 2 integrally has a hub flange 5 for attaching the brake rotor 30 and the wheel 40 of the wheel at an end portion on the outboard side. A hub bolt 6 for fixing the brake rotor 30 and the wheel 40 of the wheel is implanted at a circumferentially equidistant position of the hub flange 5 and can be fastened by a nut 7.

On the other hand, the outer member 10 is integrally formed with double-row track surfaces 10a and 10b on the inner periphery. Between the raceway surfaces 10a and 10b and the raceway surfaces 2a and 3a, double-row rolling elements 20 and 20 arranged equally around the circumference are accommodated in a freely rollable manner.
JP2003-154801A (P2003-154801A)

  As a method for improving the hub flange runout accuracy in the wheel bearing unit, for example, Patent Document 1 discloses a method for secondary processing of a hub flange of a completed bearing. According to this method, it is possible to ensure the hub flange runout accuracy as the initial quality.

  However, the structure is such that the hub flange made of steel and the brake rotor, usually made of cast iron or cast steel, are fastened to transmit the driving force, braking force, and vehicle load to the wheel, and the braking force is input from the brake rotor. The fretting wear occurs at the contact surface between the hub flange and the brake rotor.

  As a result, it is difficult to maintain the hub flange runout accuracy over a long period of time, and even if the hub flange is subjected to secondary machining at an angle and cost, the effect does not last long.

  The present invention has been made in view of the circumstances as described above, and maintains high hub flange runout accuracy even after the start of use, takes measures against hub flange runout over time, and reduces the influence of heat generated by the brake rotor. An object is to provide an axle structure that can be reduced.

In order to achieve the above object, the axle structure according to the present invention is:
Around the hub bolt hole of the hub flange for mounting the brake rotor and wheel,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor is convex,
The height dimension of the convex processing is larger than the depth dimension of the counterbore,
When the convex portion of the opposing surface of the brake rotor is inserted into the counterbore portion of the hub flange, a gap is formed between the hub flange surface and the opposing surface of the brake rotor.

The axle structure according to the present invention is
The hub bolt hole periphery of the hub flange for mounting the brake rotor and wheel is convex,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor,
The height dimension of the convex processing is larger than the depth dimension of the counterbore,
When the convex portion of the hub flange is inserted into the countersink portion of the opposing surface of the brake rotor, a gap is formed between the hub flange surface and the opposing surface of the brake rotor.

The axle structure according to the present invention is
Around the hub bolt hole of the hub flange for mounting the brake rotor and wheel,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor,
A hollow boss with a hole through which a hub bolt wider than the sum of the two countersink depths can be inserted is inserted between the two countersinks,
After assembly, a gap is formed between the hub flange surface and the opposing surface of the brake rotor.

  Suitably, the material of the said boss | hub is a material which does not raise | generate a friend metal phenomenon with steel materials.

  Preferably, at least one set of counterbore, the diameter of the convex portion or the boss is different from the other, and assembly in only one phase is possible.

  According to the present invention, it is possible to maintain high hub flange runout accuracy even after the start of use, take measures against hub flange runout deterioration, and reduce the influence of heat generated by the brake rotor.

  Hereinafter, an axle structure according to an embodiment of the present invention will be described with reference to the drawings.

(First embodiment)
In the present embodiment, a method for preventing fretting of the hub flange is proposed. Fretting wear is a wear phenomenon that occurs due to relative slip of opposing surfaces. In the conventional structure, the opposite surface of the hub flange surface and the hub flange of the brake rotor hits the entire surface and is fastened with hub bolts to support the road surface reaction force that changes momentarily under driving conditions. Is communicating. Since the compression pressure on the surface due to fastening of the hub bolt decreases as the distance from the hub bolt increases, fretting occurs at a site slightly away from the hub bolt.

  Therefore, fretting can be reduced by reducing the contact area between the hub flange and the brake rotor, increasing the contact surface pressure, and preventing relative slip from occurring due to road reaction force and torque transmission.

  Further, if the hub flange surface and the brake rotor surface are provided with projections and depressions and are fitted and torque is transmitted from the fitting surface, fretting is still prevented.

  Furthermore, since the brake is a part that generates a lot of heat, a slip phenomenon due to a temperature change must be taken into consideration. Even in that case, it is effective to reduce the contact area between the hub flange and the brake rotor. That is, the cooling effect of the brake rotor is enhanced, and the temperature difference between the hub flange and the brake rotor can be reduced. In addition, heat transfer to the bearing is reduced, and a secondary effect of reducing thermal deterioration of grease and seals can be expected.

  From the above viewpoint, in the present embodiment, as shown in FIGS. 1A and 1B, the periphery of the hub bolt hole of the hub flange 5 for attaching the brake rotor 30 and the wheel 40 is processed into a countersink 51. The periphery of the hub bolt hole on the surface of the brake rotor 30 facing the hub flange 5 is processed into a convex portion 52, and the height dimension of the convex portion 52 is set larger than the depth dimension of the counterbore portion 51. FIG. 1A is a cross-sectional view before the assembly of the axle structure according to the first embodiment of the present invention, and FIG. 1B is a cross-sectional view after the assembly.

  Thereby, when the convex part 52 of the opposing surface of the brake rotor 30 is inserted into the counterbore 51 of the hub flange 5, a gap is formed between the surface of the hub flange 5 and the opposing surface of the brake rotor 30. Therefore, it is possible to maintain high deflection accuracy of the hub flange 5 even after the start of use, take measures against deterioration of the hub flange 5 over time, and reduce the influence of heat generated by the brake rotor 30.

(Second Embodiment)
FIG. 2A is a cross-sectional view before the assembly of the axle structure according to the second embodiment of the present invention, and FIG. 2B is a cross-sectional view after the assembly.

  As described in the first embodiment, the hub flange 5 for attaching the brake rotor 30 and the wheel 40 as shown in FIGS. 2 (a) and 2 (b) also from the same point of view in the present embodiment. The hub bolt hole periphery is processed into a convex portion 61, the hub bolt hole periphery of the surface facing the hub flange 5 of the brake rotor 30 is processed into a counterbored portion 62, and the height dimension of the convex portion 61 is It is set larger than the depth dimension.

  Thereby, when the convex part 61 of the hub flange 5 is inserted into the countersink part 62 on the opposing surface of the brake rotor 30, a gap is formed between the surface of the hub flange 5 and the opposing surface of the brake rotor 30. Therefore, it is possible to maintain high deflection accuracy of the hub flange 5 even after the start of use, take measures against deterioration of the hub flange 5 over time, and reduce the influence of heat generated by the brake rotor 30.

(Third embodiment)
FIG. 3A is a cross-sectional view of the axle structure according to the third embodiment of the present invention before assembly, and FIG. 3B is a cross-sectional view after the assembly.

  As described in the first embodiment, the hub flange 5 for attaching the brake rotor 30 and the wheel 40 as shown in FIGS. 3 (a) and 3 (b) also from the same point of view in the present embodiment. The hub bolt hole periphery is processed into a counterbored portion 71, the hub bolt hole periphery of the surface facing the hub flange 5 of the brake rotor 30 is also processed into a counterbored portion 72, and between the two counterbored portions 71, 72, A hollow boss 73 having a hole through which the hub bolt 6 having a width wider than the total depth of the two counterbore portions 71 and 72 can be inserted is set.

  Thereby, a gap is formed between the surface of the hub flange 5 and the opposing surface of the brake rotor 30 after assembly. Therefore, it is possible to maintain high deflection accuracy of the hub flange 5 even after the start of use, take measures against deterioration of the hub flange 5 over time, and reduce the influence of heat generated by the brake rotor 30.

(Fourth embodiment)
By the way, fretting wear increases by a so-called friend metal phenomenon when steel materials are opposed to each other. It can be solved if the material of the hub flange or brake rotor can be changed, but the change is not easy. The component having the hub flange in the hub bearing unit of the hub 2 or the hub 3 type also has a bearing raceway surface. Therefore, the hub flange needs to be made of a material that satisfies the requirements (high strength, rolling fatigue life) required for the bearing. Therefore, the material of the hub flange must be medium carbon steel or high carbon steel.

  Further, even in the case of a hub bearing unit of 1.5 or 2.5 type of hub, it is general that induction hardening and tempering are performed from the fitting surface of the bearing to the rear surface of the hub flange in order to improve the rotational bending strength.

  On the other hand, since the brake rotor dissipates heat from the brake, it has a complicated shape with fins and needs to be mass-produced by casting. Therefore, cast iron or cast steel is the best.

  Therefore, in this embodiment, the boss 73 shown in the third embodiment is used, and if the material is a material that does not cause a friend metal phenomenon with a steel material, the friend problem can be solved. Specifically, the boss 73 may be made of high-tensile brass, stainless steel, hard plating, or the like.

(Fifth embodiment)
FIG. 4 is a schematic diagram showing the layout of the fitting portion of the hub bolt according to the fifth embodiment of the present invention.

  Even if the fretting is suppressed as in the first to fourth embodiments, when disassembling and reassembling at the time of tire replacement or the like, if assembled in a phase different from that before disassembling, the hub flange runout after reassembling is deteriorated.

  Therefore, in the present embodiment, the diameters of at least one set of the counterbore part, the convex part, or the boss are different from the other, and are configured to be assembled in only one phase.

  That is, in FIG. 4, only the dimension of at least one fitting portion indicated by reference numeral 80 is changed with respect to the other fitting portions.

  In addition, this invention is not limited to embodiment mentioned above, A various deformation | transformation is possible.

(A) is sectional drawing before the assembly of the axle structure which concerns on 1st Embodiment of this invention, (b) is sectional drawing after the assembly. (A) is sectional drawing before the assembly of the axle structure which concerns on 2nd Embodiment of this invention, (b) is sectional drawing after the assembly. (A) is sectional drawing before the assembly of the axle structure which concerns on 3rd Embodiment of this invention, (b) is sectional drawing after the assembly. FIG. 20 is a schematic diagram illustrating a layout of a fitting portion of a hub bolt according to a fifth embodiment of the present invention. It is a longitudinal cross-sectional view of the axle structure which concerns on a prior art example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inner member 2 Hub 2a Raceway surface 3 Inner ring 3a Raceway surface 4 Step part 5 Hub flange 6 Hub bolt 7 Nut 10 Outer member 10a Raceway surface 10b Raceway surface 20 Rolling body 30 Brake rotor 40 Wheel 51 Countersink part 52 Convex part 61 Convex part 62 Countersink part 71, 72 Countersink part 73 Boss 80 Fitting part

Claims (5)

Around the hub bolt hole of the hub flange for mounting the brake rotor and wheel,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor is convex,
The height dimension of the convex processing is larger than the depth dimension of the counterbore,
An axle structure characterized in that a gap is formed between the hub flange surface and the opposing surface of the brake rotor when the convex portion of the opposing surface of the brake rotor is inserted into the countersink portion of the hub flange. The hub bolt hole periphery of the hub flange for mounting the brake rotor and wheel is convex,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor,
The height dimension of the convex processing is larger than the depth dimension of the counterbore,
An axle structure characterized in that a gap is formed between the hub flange surface and the opposing surface of the brake rotor when the convex portion of the hub flange is inserted into the countersink portion of the opposing surface of the brake rotor. Around the hub bolt hole of the hub flange for mounting the brake rotor and wheel,
Around the hub bolt hole on the surface facing the hub flange of the brake rotor,
A hollow boss with a hole through which a hub bolt wider than the sum of the two countersink depths can be inserted is inserted between the two countersinks,
Axle structure characterized in that a gap is created between the hub flange surface and the opposing surface of the brake rotor after assembly.   The axle structure according to claim 3, wherein the material of the boss is a material that does not cause a friend metal phenomenon with a steel material.   The axle structure according to any one of claims 1 to 4, wherein at least one set of counterbore, convex portion or boss has a diameter different from the other and can be assembled in only one phase.

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