JP2006206047A - Wheel bearing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing unit capable of improving the squareness of an outer side surface 27 of a mounting flange 13 provided on a hub 8 with respect to the center of rotation of the hub 8, and preventing occurrence of judder during the braking by suppressing the vibration of a rotor coupled with and fixed to the outer side surface 27. <P>SOLUTION: The outer side surface 27 is machined after an oblique lattice portion is hardened by heat treatment on a part of the outer circumferential surface of the hub 8. Next, an inner ring track 14a and a small diameter stepped portion 15 formed on the outer circumferential surface of the hub 8 are machined with the outer side surface 27 as the reference surface. As a result, distortion caused by the heat treatment can be prevented to cause the vibration. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a wheel bearing unit for supporting a vehicle wheel and a rotating rotor for braking such as a rotor or a drum, and an improvement in a method for manufacturing such a wheel bearing unit.

  A wheel 1 constituting a wheel of an automobile and a rotor 2 constituting a disc brake as a braking device are rotatably supported on a knuckle 3 constituting a suspension device, for example, by a structure as shown in FIG. That is, the outer ring 6 that is a stationary wheel and that constitutes the wheel bearing unit 5 that is the subject of the present invention is fixed to the circular support hole 4 portion formed in the knuckle 3 by a plurality of bolts 7. On the other hand, the wheel 1 and the rotor 2 are coupled and fixed to a hub 8 constituting the wheel bearing unit 5 by a plurality of studs 9 and nuts 10.

  Double row outer ring raceways 11a and 11b, each of which is a stationary side raceway surface, are formed on the inner peripheral surface of the outer ring 6, and a coupling flange 12 is formed on the outer peripheral surface. Such an outer ring 6 is fixed to the knuckle 3 by connecting the connecting flange 12 to the knuckle 3 with the bolts 7.

  On the other hand, a part of the outer peripheral surface of the hub 8 is an opening at the outer end of the outer ring 6 (outside means a portion that is outside in the width direction when assembled to the automobile, and is the left side of each figure. The mounting flange 13 is formed in a portion protruding from the right side of each drawing, which is the center side in the width direction in the assembled state to the automobile. The wheel 1 and the rotor 2 are coupled and fixed to one side surface (outer side surface in the illustrated example) of the mounting flange 13 by the studs 9 and the nuts 10. Further, an inner ring raceway 14a is formed on the outer peripheral surface of the intermediate portion of the hub 8 at a portion of the double row outer ring raceways 11a and 11b that faces the outer outer raceway 11a. Further, an inner ring 16 is externally fitted and fixed to a small diameter step portion 15 formed at the inner end portion of the hub 8. The inner ring raceway 14b formed on the outer peripheral surface of the inner ring 16 is opposed to the inner outer ring raceway 11b of the double row outer ring raceways 11a and 11b.

  Between each of the outer ring raceways 11a and 11b and each of the inner ring raceways 14a and 14b, a plurality of balls 17 and 17 each serving as a rolling element can be rolled while being held by cages 18 and 18, respectively. Provided. With this configuration, a double-row angular type ball bearing which is a rear combination is configured, and the hub 8 is rotatably supported on the inner side of the outer ring 6 and can support a radial load and a thrust load. Seal rings 19a and 19b are provided between the inner peripheral surface of both ends of the outer ring 6, the outer peripheral surface of the intermediate part of the hub 8 and the outer peripheral surface of the inner end of the inner ring 16, respectively. , 17 and the external space are shut off. Further, since the illustrated example is a wheel bearing unit 5 for driving wheels (rear wheels of FR and RR vehicles, front wheels of FF vehicles, all wheels of 4WD vehicles), a spline is provided at the center of the hub 8. A hole 20 is formed. The spline shaft 22 of the constant velocity joint 21 is inserted into the spline hole 20.

  When the wheel rolling bearing unit 5 as described above is used, as shown in FIG. 4, the wheel 1 and the rotor 2 in which the outer ring 6 is fixed to the knuckle 3 and the mounting flange 13 of the hub 8 is combined with a tire (not shown). To fix. A brake disc brake is configured by combining the rotor 2 and the support and caliper (not shown) fixed to the knuckle 3. During braking, a pair of pads provided across the rotor 2 are pressed against both side surfaces of the rotor 2.

  It is known that vibrations with unpleasant noise, often called judder, often occur when braking a car. There are various known causes of such vibration, such as uneven friction between the side surface of the rotor 2 and the lining of the pad. However, it is known that the vibration of the rotor 2 is also a major cause. It has been. That is, the side surface of the rotor 2 should be perpendicular to the center of rotation of the rotor 2, but it is difficult to make it completely perpendicular due to unavoidable manufacturing errors. As a result, it is inevitable that the side surface of the rotor 2 swings in the direction of the rotation axis (left and right direction in FIG. 4), although it is somewhat, when the automobile is running. When such deflection (the amount of displacement in the left-right direction in FIG. 4) increases, judder occurs when the lining of a pair of pads is pressed against both side surfaces of the rotor 2 for braking.

  In order to suppress judder generated due to such a cause, it is important to suppress (improve) the shake (axial shake) of the side surface of the rotor 2 in the axial direction. In order to suppress this deflection, it is necessary to improve the perpendicularity of the mounting surface of the mounting flange 13 (one side surface of the mounting flange 13) with respect to the rotation center of the hub 8 and the surface accuracy of the mounting surface itself. is there. There are a plurality of elements that affect the perpendicularity and surface accuracy, respectively. However, as the elements that have a particularly large influence, the mounting surface and the raceway (outer ring raceways 11a and 11b and inner ring raceways 14a, 14b) has a heat treatment deformation with respect to the surface accuracy. In order to increase the parallelism, the inner ring raceway 14a formed on one side surface of the mounting flange 13 and the outer peripheral surface of the intermediate flange portion 15 and the small-diameter step portion 15 formed on the inner end portion of the components of the hub 8. It is necessary to finish the positional relationship with each other, and the shapes and dimensions of these parts with high accuracy. If the accuracy of the shape and size of the inner ring raceway 14a and the small diameter step portion 15 is increased in relation to the mounting surface, the perpendicularity of the mounting surface with respect to the center of rotation of the hub 8 can be improved. If the heat treatment deformation is removed from the mounting surface, the surface accuracy of the mounting surface can be improved.

  As a technique for preventing the mounting flange 13 from swinging, which is linked to the swing of the rotor 2, for example, there is one described in Patent Document 1. However, since the prior art described in Patent Document 1 precisely finishes a surface that is not originally required as a reference surface, not only does the cost increase, but consideration is given to heat-treating each component. Absent. On the other hand, the inner ring raceway 14a and the small diameter step portion 15 need to be subjected to heat treatment such as induction hardening in order to harden the surface. The shapes and dimensions of the inner ring raceway 14a and the small-diameter step portion 15 change somewhat with such heat treatment. Therefore, in the prior art described in Patent Document 1, the accuracy of each portion is as described above. It is difficult to improve sufficiently. In addition, in the case of the invention described in the above-mentioned Patent Document 1, the structure is such that a pair of inner rings, each of which is separated from the hub, is fixed to the outer peripheral surface of the hub. An error between the inner ring raceway and the inner ring raceway enters as a parallelism error between the mounting surface of the mounting flange and the inner ring raceway. Furthermore, since the contact portion between the hub and the inner ring is not processed with reference to the mounting surface of the mounting flange, it is difficult to sufficiently improve the parallelism between the mounting surface and the inner ring raceway.

  Conventionally, in order to cancel out the deflection of the mounting flange 13 and the deflection based on the shape error of the rotor 2 itself, the wheel bearing unit 5 and the rotor 2 are selected and combined, or the wheel bearing unit 5 After combining with the rotor 2, the side surface of the rotor 2 may be processed. However, in the former case, the selection work for the combination becomes troublesome, and in the latter case, the mechanical device for processing becomes complicated and large in size.

JP 10-217011 A

  In view of such circumstances, the wheel bearing unit of the present invention and the manufacturing method thereof have a structure in which the relationship between the rotation side raceway surface and the side surface of the mounting flange can be a regular relationship regardless of the deformation of each part accompanying the heat treatment. Invented to obtain at low cost.

  Of the wheel bearing unit and the manufacturing method thereof according to the present invention, the wheel bearing unit described in claim 1 has a stationary-side raceway surface on the stationary-side peripheral surface, like the conventional wheel-bearing unit described above. A stationary wheel supported and fixed to the suspension device in use, a rotating wheel having a rotating raceway surface whose surface is heat-treated and hardened on the rotating peripheral surface, and the rotating raceway surface and the stationary raceway surface. A plurality of rolling elements provided therebetween, and a mounting flange which is provided on the outer peripheral surface of the rotating wheel, and which couples and fixes the braking rotating body and wheels to the side surface in use.

  In particular, in the wheel bearing unit of the present invention, the side surface of the mounting flange for coupling and fixing the braking rotating body and the wheel is processed into a predetermined shape after heat-treating the rotating side raceway surface. It is. The rotating raceway surface is formed by processing the side surface of the mounting flange into a predetermined shape and then processing the mounting flange into a predetermined shape and size using the side surface as a reference.

  Furthermore, in the method for manufacturing the wheel bearing unit according to the second aspect, the side surface of the mounting flange is processed into a predetermined shape after the rotation-side raceway surface portion of the rotating wheel is heat-treated and cured. Next, the rotating side raceway surface is processed into a predetermined shape and size by using this side surface as a reference surface.

According to the wheel bearing unit of the present invention configured as described above and the manufacturing method thereof, the relationship between the rotation side raceway surface and the side surface of the mounting flange can be a normal relationship regardless of the deformation of each part accompanying the heat treatment. . As a result, the perpendicularity of the side surface of the mounting flange with respect to the rotation center of the rotating wheel can be increased, and the vibration of the braking rotating body fixed to the mounting flange can be suppressed.
For this reason, unpleasant noise and vibration generated during braking can be suppressed without particularly increasing the cost.

[First example of embodiment]
1 and 2 show a first example of an embodiment of the present invention. A coupling flange 12 for coupling and fixing the outer ring 6 to the knuckle 3 (FIG. 4) is provided on the outer peripheral surface of the outer ring 6 which is a stationary ring. Further, double row outer ring raceways 11a and 11b, each of which is a stationary side raceway surface, are formed on the inner circumference surface of the outer ring 6 that is a stationary side circumferential surface. 1 including the outer ring raceways 11a and 11b, the portion shown by the oblique lattice in the upper half of FIG. 1 on the inner circumferential surface of the outer ring 6 is hardened over the entire circumference by induction hardening.

  In addition, inner ring tracks 14a and 14b corresponding to the rotation-side track surfaces are provided on the outer peripheral surfaces of the hub 8 and the inner ring 16 corresponding to the rotating wheels and facing the outer ring tracks 11a and 11b, respectively. . That is, the inner ring raceway 14a is formed directly on the outer peripheral surface of the intermediate portion of the hub 8, and the inner ring 16 having the inner ring raceway 14b formed on the outer peripheral surface thereof is connected to the small diameter step portion 15 formed on the inner end portion of the hub 8. It is fitted and fixed. The inner ring 16 is made of a hard metal such as bearing steel such as SUJ2 and is hardened and hardened to the core. Further, a portion near the outer end of the intermediate portion of the hub 8 and a portion protruding from the outer end opening of the outer ring 6 includes a wheel 1 constituting a wheel and a rotor 2 (FIG. 4) or a drum as a braking rotating body. Mounting flange 13 is provided.

  At a plurality of locations in the circumferential direction of the mounting flange 13, mounting holes 23 are formed on the same circumference around the center of rotation of the hub 8, and the base ends of the studs 24 are respectively formed in the mounting holes 23. The part is internally fitted and fixed. The stud 24 has a flange 25 formed on the base end surface thereof, and a serration portion 26 formed near the base end of the intermediate portion outer peripheral surface. Such a stud 24 is inserted into the mounting hole 23 from the inside to the outside (from right to left in FIG. 1), the serration portion 26 is press-fitted into the mounting hole 23, and the flange portion 25 is inserted into the mounting flange 13. It hits the inner surface of the. In the state where the stud 24 is fixed to the mounting flange 13 in this way, the center position in the width direction of the serration portion 26 shown by a chain line α in FIG. 1 is the mounting flange 13 shown by a chain line β in FIG. It is located inward from the center position in the thickness direction. The reason for this is as follows.

In the case of this example, the outer surface 27 (the left side surface in FIGS. 1 and 2) of the mounting flange 13 is a mounting surface on which the wheel 1 and the rotor 2 are to be mounted. Therefore, it is necessary to prevent the shape accuracy of the outer surface 27 from being deteriorated as much as possible. On the other hand, when the serration portion 26 of the stud 24 is press-fitted into the mounting hole 23, the mounting flange 13 is somewhat deformed in the vicinity of the mounting hole 23. When this deformation extends to the outer surface 27 of the mounting flange 13 and the outer surface deforms in a convex direction, the vibration of the rotor 2 coupled and fixed to the outer surface tends to increase. Therefore, the fitting portion between the mounting hole 23 and the serration portion 26 is provided as close as possible to the inside so that the outer surface 27 is not deformed in the convex direction based on the deformation. Of course, the width W ₂₆ of the serration portion 26 is sufficiently smaller than the thickness T ₁₃ of the mounting flange 13 (W ₂₆ << T ₁₃ ) as long as sufficient fitting strength can be secured. In the illustrated example, a chamfered large-diameter portion is formed at the end of the mounting hole 23 at the opening on the outer surface 27 side by counterbore or turning, so the serration portion 26 It is possible to more reliably prevent the outer surface 27 from being deformed in the convex direction due to the press fitting. Furthermore, although it is considered that it is almost unnecessary, if the outer side surface 27 is processed again after the serration portion 26 is press-fitted, the distortion of the outer side surface 27 can be surely eliminated.

  Further, the portion of the outer peripheral surface of the hub 8 indicated by the oblique lattice in the upper half of FIG. 1 is hardened over the entire periphery by induction hardening. Among these, the base end portion of the mounting flange 13 is hardened to prevent the base end portion from being plastically deformed regardless of a large moment applied to the mounting flange 13 during traveling. The inner ring raceway 14a is cured to prevent formation of indentations on the inner ring raceway 14a regardless of the large surface pressure applied to the contact portion with the balls 17, 17 described below. The small-diameter step portion 15 is cured to prevent the small-diameter step portion 15 from being plastically deformed regardless of a large radial load applied from the inner ring 16. Further, the portion between the small-diameter step portion 15 and the inner ring raceway 14a is hardened to prevent plastic deformation of the intermediate portion regardless of a large moment load or thrust load applied during traveling.

  Further, between the outer ring raceways 11a and 11b and the inner ring raceways 14a and 14b, a plurality of balls 17 and 17 each of which is a rolling element are rolled while being held by cages 18 and 18, respectively. It is provided freely. With this configuration, the hub 8 is rotatably supported on the inner diameter side of the outer ring 6, and the wheel including the wheel 1 and the rotor 2 can be rotatably supported with respect to the knuckle 3. Seal rings 19a and 19b are provided between the inner peripheral surface of both ends of the outer ring 6, the outer peripheral surface of the intermediate part of the hub 8 and the outer peripheral surface of the inner end of the inner ring 16, respectively. , 17 and the external space are shut off to prevent leakage of grease sealed in the space and to prevent foreign matter from entering the space.

  In the wheel bearing unit 5 as described above, the outer surface 27 of the mounting flange 13 for connecting and fixing the wheel 1 and the rotor 2 is shown in the upper half of FIG. The outer peripheral surface of the intermediate part of the hub 8 is hardened by induction hardening, which is a kind of heat treatment, and then processed into a predetermined shape. That is, the oblique lattice portion is subjected to high-frequency heat treatment to harden the oblique lattice portion, and after the hub 8 is deformed due to the heat treatment, the outer surface 27 is subjected to machining such as turning, and the outer surface 27 is subjected to external heat treatment. The side surface 27 is a flat surface.

  Further, the inner ring raceway 14a formed directly on the outer peripheral surface of the intermediate portion of the hub 8 and the outer peripheral surface and step surface of the small-diameter step portion 15 formed on the inner end portion of the hub 8 form the outer surface 27 of the mounting flange 13. After processing into a flat surface, as shown in FIG. 2, the outer surface 27 is processed into a predetermined shape and size as a reference. That is, the backing plate 28 is abutted against the outer surface 27, and the backing plate 28 and the mounting flange 13 are coupled by a magnetic adsorption force or the like. Then, the hub 8 is rotated by rotating the backing plate 28. At this time, the center of rotation of the hub 8 is an axis orthogonal to the outer surface 27. Therefore, an outer surface of the inner ring raceway 14a and the small-diameter step portion 15 shown by a broken line in FIG. 2 is provided while a shoe (not shown) is brought into sliding contact with the outer surface of the hub 8 and positioning in the radial direction of the hub 8 is performed. Then, the stepped surfaces are machined to make the shape of each surface desired, such as grinding or precision turning.

  Since such machining is performed with an axis orthogonal to the outer surface 27 as the center of rotation, the outer ring 27, the inner ring raceway 14a formed directly on the outer peripheral surface of the intermediate portion of the hub 8, and the small diameter stepped portion. The positional relationship between the outer ring of the inner ring 16 (FIG. 1) fitted to the inner ring 15 and the inner ring raceway 14b becomes normal regardless of the thermal deformation based on the high-frequency quenching process. As a result, in the state in which the wheel bearing unit 5 as shown in FIG. 1 is assembled, it is possible to suppress the shake of the outer side surface 27 slightly.

[Second Example of Embodiment]
Next, FIG. 3 shows a second example of the embodiment of the present invention. In the case of this example, after the outer surface 27 of the mounting flange 13 provided on the outer peripheral surface of the hub 8 is finished to be a flat surface, the outer end of the hub 8 is gripped by the chuck 30 and the hub 8 The inner ring raceway 14a formed directly on the outer peripheral surface of the intermediate portion and the outer peripheral surface and step surface of the small diameter step portion 15 formed on the inner end of the hub 8 are processed into a predetermined shape and size. At this time, one side surface of the chuck 30 in the axial direction (right end surface in FIG. 3) abuts on the outer surface 27, and this outer surface 27 is used as a reference surface for processing. Further, the inner peripheral surface of the chuck 30 is brought into contact with the outer peripheral surface of the cylindrical portion 31 formed at the outer end portion of the hub 8 to suppress displacement of the hub 8 in the radial direction. In the case of this example, the radial positions of the inner ring raceway 14a directly formed on the outer peripheral surface of the intermediate portion of the hub 8 and the outer peripheral surface of the small diameter step portion 15 formed on the inner end portion of the hub 8 are more strict. Can be regulated. As a result, it is possible to suppress the displacement of the wheel 1 and the rotor 2 (FIG. 4) in the radial direction and to suppress the vibration during the traveling of the automobile. Other configurations and operations are the same as those in the case of the first example described above, and thus illustrations and explanations of equivalent parts are omitted.

Sectional drawing which shows the 1st example of embodiment of this invention. Sectional drawing which shows the state which processes the outer peripheral surface of a hub in a 1st example. Sectional drawing which shows the state which processes the outer peripheral surface of a hub in the 2nd example of embodiment of this invention. Sectional drawing which shows one example of the assembly | attachment state of the wheel bearing unit used as the object of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Wheel 2 Rotor 3 Knuckle 4 Support hole 5 Wheel bearing unit 6 Outer ring 7 Bolt 8 Hub 9 Stud 10 Nut 11a, 11b Outer ring track 12 Coupling flange 13 Mounting flange 14a, 14b Inner ring track 15 Small diameter step 16 Inner ring 17 Ball 18 Holding 19a, 19b Seal ring 20 Spline hole 21 Constant velocity joint 22 Spline shaft 23 Mounting hole 24 Stud 25 ridge part 26 Serration part 27 Outer surface 28 Backing plate 29 Large diameter part 30 Chuck 31 Cylindrical part

Claims (2)

  A stationary wheel having a stationary raceway surface on the stationary side circumferential surface and supported and fixed to the suspension device in use; a rotating wheel having a rotational raceway surface whose surface is heat-treated and hardened on the rotational side circumferential surface; and A plurality of rolling elements provided between the rotating side raceway surface and the stationary side raceway surface, and provided on the outer peripheral surface of the rotating wheel, the braking rotary body and wheels are coupled and fixed to the side surface in use. In the wheel bearing unit provided with the mounting flange, the side surfaces of the mounting flange for coupling and fixing the braking rotating body and the wheel are processed into a predetermined shape after heat-treating the rotating side raceway surface. The rotation-side raceway surface is a wheel bearing characterized in that the side surface of the mounting flange is processed into a predetermined shape and then processed into a predetermined shape and dimensions with the side surface as a reference. unit.   2. A method for manufacturing a wheel bearing unit according to claim 1, wherein the rotating side raceway surface portion of the rotating wheel is heat-treated and hardened, the side surface of the mounting flange is processed into a predetermined shape, and then the rotation is performed. A method for manufacturing a wheel bearing unit, wherein a side raceway surface is processed into a predetermined shape and dimensions by using the side surface as a reference surface.

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