Patent ID: 7147379

Claim:
A wheel support bearing assembly which comprises: an outer member; an inner member positioned inside the outer member to define an annular space therebetween; at least one row of rolling element accommodated within the annular space and operatively interposed between the inner and outer members; a sealing device for sealing an open end of the annular space, and a protective cover made of a non-magnetic material; said sealing device comprising: first and second annular sealing plates fitted to different members out of the inner and outer members, each of the first and second sealing plate including a generally cylindrical wall and a radial wall assembled together to represent a generally L-shaped section, the first and second sealing plates being positioned within the annular space in face-to-face relation with each other, the first sealing plate being fitted to a rotating member out of the inner and outer members with the radial wall of the first sealing plate positioned on one side adjacent an exterior of the bearing assembly; an annular multi-pole magnet having a plurality of different magnetic poles alternating in a direction circumferentially thereof and fitted to the radial wall of the first sealing plate; the second sealing plate including a side sealing lip, slidingly engaged with the radial wall of the first sealing plate and opposedly extending radial sealing lips slidingly engaged with the cylindrical wall of the first sealing plate, the cylindrical wall of the second sealing plate being positioned adjacent a slight distance from a free edge of the radial wall of the first sealing plate with a slight radial gap defined therebetween; and wherein the protective cover is disposed exteriorly of the multi-pole magnet and positioned adjacent thereto with a predetermined air gap defined therebetween so that a number of revolution can be detected through the protective cover.