JP4151187B2 - Axle bearing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an axle bearing device in which a hub unit and a constant velocity joint are integrated.
[0002]
[Prior art]
A conventional axle bearing device is shown in FIG. This axle bearing device has an inner rotating member 83 in which an outer cylinder portion 82 is fitted on the outer side of an inner cylinder portion 81, and an outer ring 85 fitted in the inner rotating member 83 from the outside. 85 and the inner rotary member 83 are provided with two rows of ball arrays 86 and 87, and the inner rotary member 83 extends axially outward from the inner cylindrical portion 81 in a cup shape, etc. It is integrated with the outer joint member 88 of the speed joint.
[0003]
The outer peripheral surface of the outer cylindrical portion 82 forms a first track surface 82A, and the outer peripheral surface of the base 90 of the inner rotating member 83 adjacent to the first track surface 82A forms a second track surface 90A. A third raceway surface 85A and a fourth raceway surface 85B are formed on the inner peripheral surface of the outer ring 85 facing the first and second raceway surfaces 82A and 90A. The raceway surface 82 A of the outer cylinder portion 82, the ball rows 86 and 87, the outer ring 85, and the raceway surface 90 A of the base portion 90 constitute the bearing portion 102 of the hub unit 101.
[0004]
Also, balls (not shown) grooves 91 and 92 are formed on the inner surface of the outer joint member 88 of the inner rotating member 83. A large amount of heat is generated by sliding with the balls 91 and 92 for the balls.
[0005]
[Problems to be solved by the invention]
By the way, when the heat generated in the outer joint member 88 of the constant velocity joint is transmitted to the raceway surface 90A of the base portion 90 of the inner rotary member 83 and the raceway surface 82A of the outer cylinder portion 82, the hardness of the raceway is reduced. The life of the bearing portion 102 is reduced.
[0006]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an axle bearing device that makes it difficult for heat generated in a constant velocity joint to be transmitted to a bearing portion of a hub unit, thereby improving the life of the bearing portion.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, the axle bearing device of the invention of claim 1 has a hub unit bearing portion in which a plurality of rolling elements are disposed between an outer ring and an inner rotating member, and the inner rotating member is An outer cylinder, an inner cylinder part fitted inside the outer cylinder, a base part integral with the inner cylinder part, and integral with the base part and extending axially outward from the base part in a cup shape is composed of an outer joint member of the constant velocity joint that,
In the axle bearing device in which the raceway surface of the inner rotating member is formed on the outer peripheral surface of the base and the outer peripheral surface of the outer cylinder between the outer joint member of the constant velocity joint and the outer cylinder ,
A first hardened layer formed by subjecting the inner peripheral surface of the outer joint member of the constant velocity joint to carburizing and quenching or carbonitriding and quenching, and having a higher carbon content than the surroundings and a lower thermal conductivity than the surroundings; ,
A second hardened layer formed by subjecting the raceway surface of the inner rotating member of the bearing portion of the hub unit to carburizing quenching or carbonitriding quenching and having a higher carbon content than the surroundings and a lower thermal conductivity than the surroundings. And
The outer peripheral surface of the outer joint member of the constant velocity joint is not subjected to carburizing quenching and carbonitriding quenching,
The first and second hardened layers suppress heat transfer from the inner peripheral surface of the outer joint member of the constant velocity joint to the raceway surface of the inner rotating member of the bearing portion of the hub unit. Yes.
[0008]
In the first aspect of the invention, since the carburizing quenching or carbonitriding quenching is performed on the inner peripheral surface of the outer joint member of the constant velocity joint, the carbon content increases on the inner peripheral surface of the outer joint member, and the thermal conductivity is increased. descend. Therefore, it is possible to suppress the heat generated on the inner peripheral surface of the outer joint member of the constant velocity joint from being easily transmitted to the bearing portion of the hub unit, and to suppress the decrease in the hardness of the raceway portion of the bearing portion. Decline can be prevented.
[0009]
In the first aspect of the present invention, since the carburizing quenching or carbonitriding quenching is performed on the raceway surface of the inner rotary member of the bearing portion, the carbon amount increases on the raceway surface of the inner rotary member, and the thermal conductivity decreases. . Therefore, the heat generated on the inner peripheral surface of the outer joint member of the constant velocity joint is hardly transmitted to the raceway surface of the bearing portion, and the life of the bearing portion can be improved.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.
[0011]
FIG. 1 shows a cross section of an embodiment of an axle bearing device of the present invention. In this axle bearing device, two rows of ball rows 3 and 5 are arranged between the outer ring 1 and the inner rotating member 2. The inner rotating member 2 includes an outer cylinder 6, an inner cylinder part 7 fitted inside the outer cylinder 6, a base 8, and an outer joint of a constant velocity joint extending axially outward from the base 8 in a cup shape. It is comprised with the member 10. FIG. The inner cylinder portion 7, the base portion 8, and the outer joint member 10 are integrated to form an inner integrated portion 9. On the inner surface of the outer joint member 10 are formed sliding grooves 19 and 20 in which balls (not shown) slide.
[0012]
The ball train 3 is disposed between a first track 11 formed on the inner peripheral surface of the outer ring 1 and a third track 12 formed on the outer peripheral surface of the outer cylinder 6. 1 is disposed between the second track 13 formed on the inner peripheral surface of the first track and the fourth track 14 formed on the outer peripheral surface of the base 8. The outer ring 1, the ball rows 3 and 5, the outer cylinder 6 and the base portion 8 constitute a bearing portion 16 of the hub unit. Reference numerals 31 and 32 denote seal portions.
[0013]
In this axle bearing device, the carbonitriding and quenching portion 24 was formed by performing carbonitriding and quenching on the inner peripheral surface 10A of the outer joint member 10 of the constant velocity joint. The third track 12 formed on the outer peripheral surface of the outer cylinder 6 of the hub unit is subjected to carbonitriding and quenching to form an annular carbonitriding and quenching portion 25. Further, the fourth track 14 formed on the outer peripheral surface of the base portion 8 is subjected to carbonitriding and quenching to form an annular carbonitriding and quenching portion 26. Here, the inner integrated portion 9 and the outer cylinder 6 are made of carbon steel S55C, and carbon mass nitriding and quenching is performed on the surface thereof, so that the carbon mass% of the carburized and quenched portions 24, 25, and 26 is 0.80 to 1. 60. Moreover, the effective hardening depth of the said carburizing quenching part 24,25,26 was about 1 mm-2 mm.
[0014]
In the axle bearing device having the above-described configuration, the inner peripheral surface 10 </ b> A of the outer joint member 10 of the constant velocity joint is subjected to carbonitriding and quenching to form the annular carbonitriding and quenching portion 24. On the surface, the carbon content increases and the thermal conductivity decreases. Therefore, it is possible to suppress the heat generated on the inner peripheral surface of the outer joint member 10 of the constant velocity joint from being easily transmitted to the bearing portion 16 of the hub unit, and to reduce the hardness of the raceways 12 and 14 of the bearing portion 16. The life of the bearing portion 16 can be prevented from being reduced.
[0015]
Further, in this embodiment, carbonitriding is performed on the third raceway 12 of the outer cylinder 6 and the fourth raceway 14 of the base portion 8 constituting the bearing portion 16, so that the raceways 12 and 13 of the inner rotary member 2 are used. Carbon content increases and thermal conductivity decreases. Therefore, the heat generated on the inner peripheral surface of the outer joint member 10 of the constant velocity joint is hardly transmitted to the raceway surfaces 12 and 14 of the bearing portion 16, and the life of the bearing portion 16 can be improved.
[0016]
In the embodiment described above, carbonitriding and quenching are performed on both the inner peripheral surface 10A of the outer joint member 10 and the tracks 12 and 14, but carburizing and quenching may be performed instead of the carbonitriding and quenching.
[0017]
【The invention's effect】
As is clear from the above, the axle bearing device of the invention of claim 1 has a bearing portion of a hub unit in which a plurality of rolling elements are arranged between the outer ring and the inner rotating member, and the inner rotating member is In the axle bearing device integrated with the outer joint member of the constant velocity joint, the inner peripheral surface of the outer joint member of the constant velocity joint was subjected to carburizing or carbonitriding. Therefore, the amount of carbon increases on the inner peripheral surface of the outer joint member, the thermal conductivity decreases, and the heat generated on the inner peripheral surface of the outer joint member of the constant velocity joint becomes difficult to be transmitted to the bearing portion of the hub unit. Thus, it is possible to suppress a decrease in the hardness of the raceway portion of the bearing portion, and it is possible to prevent a decrease in the life of the bearing portion.
[0018]
Further, an axle bearing apparatus of the first aspect of the present invention were subjected to carburizing or carbonitriding quenching the raceway surface of the inner rotating member of the upper SL bearing portion. Accordingly, the amount of carbon increases on the raceway surface of the inner rotating member, the thermal conductivity decreases, and the heat generated on the inner peripheral surface of the outer joint member of the constant velocity joint becomes difficult to be transmitted to the raceway surface of the bearing portion. The life of the bearing portion can be improved.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an embodiment of an axle bearing device of the present invention.
FIG. 2 is a cross-sectional view of a conventional axle bearing device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Outer ring, 2 ... Inner rotation member, 3, 5 ... Ball train, 6 ... Outer cylinder, 7 ... Inner cylinder part,
8 ... Base, 9 ... Inner integral part, 10 ... Outer joint member, 11 ... First track,
12 ... 3rd track, 13 ... 2nd track, 14 ... 4th track, 16 ... Bearing part,
24, 25, 26 ... Carbonitriding quenching part.

Claims (1)

A hub unit bearing portion in which a plurality of rolling elements are disposed between the outer ring and the inner rotating member, the inner rotating member includes an outer tube, and an inner tube portion fitted inside the outer tube; A base part integral with the inner cylindrical part, and an outer joint member of a constant velocity joint that is integral with the base part and extends axially outward from the base part in a cup shape ,
In the axle bearing device in which the raceway surface of the inner rotating member is formed on the outer peripheral surface of the base and the outer peripheral surface of the outer cylinder between the outer joint member of the constant velocity joint and the outer cylinder ,
A first hardened layer formed by subjecting the inner peripheral surface of the outer joint member of the constant velocity joint to carburizing and quenching or carbonitriding and quenching, and having a higher carbon content than the surroundings and a lower thermal conductivity than the surroundings; ,
A second hardened layer formed by subjecting the raceway surface of the inner rotating member of the bearing portion of the hub unit to carburizing quenching or carbonitriding quenching and having a higher carbon content than the surroundings and a lower thermal conductivity than the surroundings. And
The outer peripheral surface of the outer joint member of the constant velocity joint is not subjected to carburizing quenching and carbonitriding quenching,
The first and second hardened layers suppress heat transfer from the inner peripheral surface of the outer joint member of the constant velocity joint to the raceway surface of the inner rotating member of the bearing portion of the hub unit. Axle bearing device.

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