Wheel bearing apparatus incorporated with a wheel speed detecting apparatus and method of its assembly

1. A wheel bearing apparatus incorporating a wheel speed detecting apparatus formed by a unit of a wheel hub, a double row rolling bearing and a constant velocity universal joint, the double row rolling bearing comprising:

an outer member integrally formed, on its outer circumference, with a body mounting flange to be mounted on a knuckle (N) forming part of a suspension apparatus, and said outer member formed, on its inner circumference, with double row outer raceway surfaces;

an inner member including the wheel hub with an integrally formed wheel mounting flange at one end and a cylindrical portion axially extending from the wheel mounting flange, an inner raceway surface formed on the outer circumference of the cylindrical portion, said inner raceway surface corresponding to one of the double row outer raceway surfaces, and an outer joint member of the constant velocity universal joint, the outer joint member formed with another inner raceway surface corresponding to the other of the double row outer raceway surfaces and having a shaft portion axially extending from said other inner raceway surface;

double row rolling elements rollably arranged between the outer and inner raceway surfaces;

seals mounted in annular spaces formed at opposite ends of the outer member and the outer joint member;

a wheel speed detecting apparatus comprising a magnetic encoder fit onto the outer joint member;

a wheel speed sensor arranged opposite to the magnetic encoder via a predetermined air gap and mounted on the end of the outer member;

said wheel hub and said outer joint member integrally connected by caulking the shaft portion of the outer joint member onto the wheel hub:

said wheel speed detecting apparatus further comprises a sensor holder, the sensor holder including a steel annular fitting ring to be fit onto the end of the outer member, and a holding portion of plastic resin integrally molded with the annular fitting ring and having the wheel speed sensor embedded therein;

inboard side seal of said seals is arranged between the sensor holder and the outer joint member; and

that the maximum diameter of the sensor holder and the constant velocity universal joint is smaller than the inner diameter of the knuckle.

2. The wheel bearing apparatus of claim 1 , wherein the annular fitting ring comprises a cylindrical fitting portion press fit onto the outer member, a flange portion extending radially inward from the fitting portion and in intimate contact with the end face of the outer member, and a cylindrical portion axially extending from the flange portion, and said holding portion is formed so that it projects radially inward from the cylindrical portion and the seal is arranged at the inboard side of the holding portion.

3. The wheel bearing apparatus of claim 1 , wherein the magnetic encoder is arranged at the outboard side of the holding portion.

4. The wheel bearing apparatus of claim 1 , wherein the magnetic encoder is formed integrally with the seal.

5. The method for assembling a wheel bearing apparatus incorporating a wheel speed detecting apparatus of claim 1 comprising the steps of:

press fitting the seal onto the outer circumference of the outer joint member;

fitting the sensor holder onto the end of the outer member;

fitting the outer joint member into the wheel hub;

caulking the shaft portion of the outer joint member onto the wheel hub by plastically deforming the shaft portion;

fitting the sensor holder, previously guided into a joint press fitting tool, into the position of the seal after said seal press fitting step; and

mounting the sensor holder onto the outer member via the joint press fitting tool simultaneously with the fitting of the outer joint member into the wheel hub.