Bearing apparatus for a driving wheel of vehicle

#This application claims priority to Japanese Patent Application No. 2002-227447 filed Aug. 5, 2002, which application is herein expressly incorporated by reference.

#The present invention relates to a bearing apparatus for rotatably supporting a driving wheel of a vehicle.

#A power transmission apparatus transmits power from the vehicle engine to the vehicle wheels. The apparatus enables radial, axial and moment displacements caused by the bound of wheels and the turning of the vehicle during travel. The apparatus includes a drive shaft 100 arranged between the engine and the driving wheel. One end of the drive shaft 100 is connected to a differential gear 102 via a slidable constant velocity universal joint 101. The other end of the drive shaft is connected to a wheel 105 via a bearing apparatus 104 which includes a fixed type constant velocity universal joint 103, as shown in FIG. 13.

#The present invention will become more fully understood from the detailed description and the accompanying drawings, wherein:

#FIG. 1 is a longitudinal section view showing a first embodiment of the bearing apparatus for a driving wheel of the present invention;

#FIG. 2 is a cross section view showing a releasing jig of the present;

#Preferred embodiments of the present invention will be hereinafter described with reference to the accompanied drawings. FIG. 1 is a longitudinal section view showing a first embodiment of a bearing apparatus for a vehicle driving wheel of the present invention.

#The apparatus has a wheel hub 1, a double row rolling bearing 2 and an constant velocity universal joint 3 which are assembled as a unit. In the description below, the term “outboard side” of the apparatus denotes a side which is positioned outside of the vehicle body. The term “inboard side” of the apparatus denotes a side which is positioned inside of the body when the apparatus is mounted on the vehicle body.

#The wheel hub 1 is formed integrally with a wheel mounting flange 4 at the outboard side of the wheel hub 1 on which a wheel (not shown) is mounted. The wheel hub 1 has an inner raceway surface 1a at the outboard side of the double row rolling bearing 2. A cylindrical stepped portion 1b of smaller diameter axially extends from the inner raceway surface 1a. The outer circumferential surface of the wheel hub 1, from the inner raceway surface 1a to the cylindrical stepped portion 1b, is formed with a hardened layer having a surface hardness of HRC 54˜64. It is preferable to use a high frequency induction heating as a heat treatment which can easily carry out a local heating and setting of the depth of a hardened layer. The end of the stepped portion is not hardened and has a surface hardness less than HRC 25 to enable the end to be plastically deformed to form caulked portion 6.