JP2007320351A - Bearing device for wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a wheel drop from a vehicle due to breakage of a bearing device for a wheel. <P>SOLUTION: The bearing device for a wheel is formed by unitizing an outside joint member 40 of a constant velocity universal joint composing one part of a drive shaft, a hub wheel 70 having a flange 72 for fitting of the wheel and a double row rolling bearing 80; integrally forming at least one 48 of double row inner races 48 and 76 of the bearing 80 with the outside joint member 40; fitting a hollow stem part 52 of the outside joint member 40 in a through-hole 78 of the hub wheel 70 and at least partially enlarging diameter of the stem part 52 for caulking. Strength of the minimum diameter part 10 of the drive shaft is set smaller than strength of the enlarged diameter caulking part 62 and strength of the stem part 52. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a wheel bearing device.

In Patent Document 1, a hub wheel, a constant velocity universal joint, and a double row bearing are unitized, and at least one of the double row inner races of the double row bearing is formed integrally with an outer joint member of the constant velocity universal joint. A bearing device is described. That is, as shown in FIG. 4, after the stem portion 102 of the outer joint member 100 having the concavo-convex portion 104 formed on the outer peripheral surface of the end is press-fitted into the through hole 112 of the hub wheel 110, the outer joint member 100 is While the bottom of the mouse part 106 is supported, the caulking jig 116 having an outer diameter larger than the inner diameter of the through hole 108 is moved into the through hole 108 by pressing the crimping jig 116 having an outer diameter larger than the inner diameter of the through hole 108. Thus, the diameter of the stem portion 102 is increased from the inner diameter side to the outer diameter side. As a result, the concavo-convex portion 104 of the stem portion 102 bites into the inner peripheral surface of the through hole 112 of the hub wheel 110, and the outer joint member 100 and the hub wheel 110 are plastically coupled.
Japanese Patent Laid-Open No. 2001-18605

The drive wheel bearing device shown in FIG. 4 is connected to a drive shaft by a constant velocity universal joint to constitute a drive train, and serves to support the wheel rotatably and transmit torque to the wheel. Accordingly, if the torsional strength of the enlarged diameter caulking portion indicated by reference numeral 118 or the stem portion 102 of the outer joint member 100 is lower than the torsional strength of the drive shaft, if an unexpected excessive torque is input, the enlarged diameter caulking is preceded. The portion 118 or the stem portion 102 may be damaged, and the wheel may be removed.

An object of the present invention is to prevent a wheel from dropping from a vehicle due to damage to a wheel bearing device.

The present invention solves the problem by designing and setting the strength of each part so that the drive shaft is damaged in advance when an excessive torque is input. That is, the wheel bearing device according to the present invention unitizes an outer joint member of a constant velocity universal joint that constitutes a part of a drive shaft, a hub wheel having a flange for mounting a wheel, and a double row rolling bearing. , Forming at least one of the double row inner races of the bearing integrally with the outer joint member, fitting the hollow stem portion of the outer joint member into the through hole of the hub wheel, and at least partially expanding the diameter of the stem portion. It is characterized in that the strength of the minimum diameter portion of the caulking and drive shaft is weaker than both the strength of the enlarged caulking portion and the strength of the stem portion.

According to the present invention, the strength of the minimum diameter portion of the drive shaft is less than both the strength of the expanded caulking portion and the strength of the stem portion, so that when there is an excessive torque input, Will break the drive shaft in advance. As a result, although it becomes impossible to travel, the brake operation is possible and the possibility of leading to a major accident such as a wheel dropping off is low.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment applied to a drive wheel bearing device, and FIG. 2 shows a drive shaft including the device.

The drive shaft shown in FIG. 2 includes a half shaft 10 and constant velocity universal joints J1 and J2 at both ends thereof. The constant velocity universal joint J1 on the right side of FIG. 2 is a slide type, and here, a tripod type case is illustrated. The tripod type constant velocity universal joint includes an outer joint member 12 and an inner joint member 18 as main components. The outer joint member 12 is connected to a differential or the like at the stem portion 14 so that torque can be transmitted. A track groove 16 extending in the axial direction is formed on the inner periphery of the outer joint member 12. The inner joint member 18 includes a boss 20 and a journal 22, and the boss 20 is coupled to the half shaft 10 through a serration or a spline hole so that torque can be transmitted. The journal 22 protrudes in a radial direction from the circumferentially divided position of the boss 20, and a roller 26 is rotatably supported on each journal 22 via a needle bearing 24. The roller 26 rolls along the track groove 16 of the outer joint member 12 and is movable in the axial direction of the outer joint member 12. Accordingly, axial displacement (plunging) is possible between the outer joint member 12 and the inner joint member 18. In order to prevent water and foreign matter from entering the inside of the joint from the outside, and at the same time, prevent the lubricant filled in the joint from leaking, a dust boot is provided between the half shaft 10 and the outer joint member 12. 28 is attached.

The constant velocity universal joint J2 on the left side of FIG. 2 is a fixed type. As shown in FIG. 1 in an enlarged manner, the outer joint member 40 of the constant velocity universal joint J2, the hub wheel 70, and the double row rolling bearing 80 are unitized to form a wheel bearing device. Here, the side closer to the outside of the vehicle when assembled to the vehicle is referred to as the outboard side, and the left side in FIGS. 1 and 2 is the outboard side. On the other hand, the side closer to the center of the vehicle is referred to as the inboard side, and the right side in FIGS. 1 and 2 is the inboard side.

The constant velocity universal joint J <b> 2 includes an inner joint member 30, an outer joint member 40, a ball 64 as a torque transmission element, and a cage 36. The inner joint member 30 is coupled to the half shaft 10 through a serration (or spline) hole in the shaft center portion so that torque can be transmitted. The outer peripheral surface 32 of the inner joint member 30 is spherical and has ball grooves 34 extending in the axial direction at equal intervals in the circumferential direction. The outer joint member 40 includes a bell-shaped mouth portion 42 and a stem portion 52, and a ball groove 46 extending in the axial direction is formed on the spherical inner peripheral surface 44 of the mouth portion 42 at equal intervals in the circumferential direction. It is. One ball 64 is interposed between the ball groove 34 of the pair of inner joint members 30 and the ball groove 46 of the outer joint member 40. The balls 64 are housed in the pockets 38 of the cage 36, and all the balls 64 are held in the same plane by the cage 36.

An inner race 48 on the inboard side is formed on the outer peripheral surface of the outer joint member 40 near the shoulder surface 50 of the mouth portion 42.

The hub wheel 70 is provided with a flange 72 for attaching a wheel (not shown) on the outer periphery, and a hub bolt 74 for fixing the wheel (wheel disc) at a circumferentially equidistant position of the flange 72 is implanted. . An outboard inner race 76 is formed on the outer peripheral surface of the hub wheel 70 on the inboard side of the flange 72. The hub wheel 70 has an axial through hole 78 in the axial center. The shoulder surface 50 of the mouth portion 42 of the outer joint member 40 comes into contact with the end face on the inboard side of the hub wheel 70, whereby the outer joint member 40 and the hub wheel 70 are positioned in the axial direction, and the inner race 48. , 76 is defined. The stem portion 52 of the outer joint member 40 is hollowed by providing an axial through hole 54 communicating with the inside of the mouth portion 42.

The double row rolling bearing 80 includes an outer member 82 corresponding to a bearing outer ring and a double row rolling element 90. The outer joint member 40 and the hub wheel 70 described above constitute an inner member corresponding to the bearing inner ring. The outer member 82 includes a flange 84 for attachment to a vehicle body (not shown), and a double row outer race 86 for the double row rolling elements 90 is formed on the inner peripheral surface. Double row rolling elements 90 are incorporated between the inner races 48, 76 formed on the outer joint member 40 and the hub wheel 70 and the double row outer races 86 of the outer member 82, and the rolling elements 90 in each row are cages 88. At a predetermined interval. Here, the case of a double row angular contact ball bearing using a ball as the rolling element 90 is shown, but in the case of a wheel bearing device for automobiles which is heavy in weight, a double row tapered roller using a tapered roller as the rolling element. A bearing may be employed.

Seals 92 and 94 are attached to the opening portions at both ends of the outer member 82 to prevent leakage of grease filled in the bearing and intrusion of water and foreign matters from the outside. Since the through hole 54 of the stem portion 52 of the outer joint member 40 communicates with the inside of the mouse portion 42 as described above, the through hole 54 is used to prevent leakage of grease filled in the mouse portion 42. An end plate 56 is attached to the end of the mouse portion 42 side. Further, in the illustrated embodiment, an end cap 58 is mounted outside the through hole 78 of the hub wheel 70.

An uneven portion 60 is formed on the inner peripheral surface of the through hole 78 of the hub wheel 70. And as shown by the code | symbol 62, the outer peripheral surface of the stem part 52 is made to bite into the uneven | corrugated | grooved part 60 by expanding and crimping the axial end part of the stem part 52 from an inner diameter side to an outer diameter side, and an outer joint member. 40 and the hub wheel 70 are plastically coupled.

The dimensions of each part are set so as to be weaker than any of the strength of the minimum diameter portion of the drive shaft, the strength of the enlarged caulking portion, and the strength of the stem portion. More specifically, when the diameter of the half shaft 10 is D1, the outer diameter of the stem portion 52 is D2, and the outer diameter of the expanded caulking portion 62 is D3, the relationship is expressed by D3 ≧ D2> D1. Generally, the half shaft 10 is a minimum diameter portion of the drive shaft. Therefore, by establishing such a strength relationship, when an excessive torque is input, the drive shaft (half shaft 10) is damaged in advance. As a result, although it becomes impossible to run, it is possible to operate the brake and it is unlikely to lead to a major accident.

The strength of the shaft portion, the stem portion, and the caulking portion is specifically the breaking torque (T ₁ , T ₂ , T ₃ ) represented by the following formula.
Half shaft fracture _{torque: T 1 = τ 1 πD 1} 3/16 ( the case of solid shaft)
Stem breaking torque: T ₂ = τ ₂ π (D ₂ ⁴ −d ₂ ⁴ ) / 16D ₂
(Stem) breaking torque of caulking portion: T ₃ = τ ₃ π (D ₃ ⁴ −d ₃ ⁴ ) / 16D ₃
here,
D ₁ : Outer diameter of the half shaft D ₂ : Outer diameter of the stem portion, d ₂ : Inner diameter of the stem portion D ₃ : Outer diameter of the caulking portion, d ₃ : Inner diameter of the caulking portion τ ₁ : Shear stress of the half shaft (material , Considering heat treatment)
τ ₂ : Shear stress of stem (considering material and heat treatment)
τ ₃ : Shear stress of the expanded caulked portion (considering stem material)

However, regarding the caulking portion, in addition to the stem breaking torque (T ₃ ) of the caulking portion, it is necessary to consider the slip breakage torque (T ₄ ) of the portion where the hub ring uneven portion bites into the stem portion. Design a relationship that satisfies (a) to (c).
A) T ₁ <T ₂ b) T ₁ <T ₃ c) T ₁ <T ₄
It should be noted that the slip damage torque (T ₄ ) of the portion where the hub ring uneven portion bites into the stem portion can be obtained as follows.
T ₄ = Slip resistance torque per ridge of hub ring irregularity x Total number of ridges of hub ring irregularity Slip resistance torque per ridge of hub ring irregularity: confirmed by strength test

FIG. 3 is a graph showing the relationship between the applied size on the horizontal axis and the torsional strength on the vertical axis. As shown in FIG. 3, the torsion of the expanded caulking portion and the stem portion is always applied at any applicable size. It is desirable to set the strength to be greater than the torsional strength of the drive shaft. This figure shows a case where the torsional strength of the enlarged diameter caulking portion and the torsional strength of the stem portion are equal.

The longitudinal cross-sectional view of the wheel bearing apparatus which shows embodiment of this invention 1 is a longitudinal sectional view of a drive shaft including the wheel bearing device of FIG. Diagram showing the relationship between applied size and torsional strength Longitudinal sectional view for explaining caulking

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Half shaft J1 Slide type constant velocity universal joint 12 Outer joint member 14 Stem part 16 Track groove 18 Inner joint member 20 Boss 22 Journal 24 Needle bearing 26 Roller 28 Dust boot J2 Fixed type constant velocity universal joint 30 Inner joint member 32 Outer peripheral surface 34 Ball groove 36 Cage 38 Pocket 40 Outer joint member 42 Mouth portion 44 Inner peripheral surface 46 Ball groove 48 Inner race 50 Shoulder surface 52 Stem portion 54 Through hole 56 End plate 58 End cap 60 Concave portion 62 Expanded caulking portion 64 Ball 70 Hub wheel 72 Flange 74 Hub bolt 76 Inner race 78 Through hole 80 Bearing device 82 Outer member 84 Flange 86 Outer race 88 Cage 90 Rolling element 92 Seal 94 Seal 100 Outer joint member 102 Stem portion 104 Uneven portion 106 Mau Part 108 through hole 110 hub wheel 112 through hole 114 backup jig 116 caulking jig 118 caulking part

Claims (1)

The outer joint member of the constant velocity universal joint that forms part of the drive shaft, the hub wheel with the flange for mounting the wheel, and the double row rolling bearing are unitized, and at least one of the double row inner race of the bearing Is formed integrally with the outer joint member, and the hollow stem portion of the outer joint member is fitted into the through hole of the hub wheel and the stem portion is at least partially enlarged and caulked to increase the strength of the minimum diameter portion of the drive shaft. The wheel bearing device is weaker than both the strength of the expanded caulking portion and the strength of the stem portion.

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