Wheel bearing device

Abstract: A pulser ring (4) and a pick up sensor (5) are sealingly housed by a seal (6) so as to prevent the penetration of foreign matters. The pulser ring (4) is fixedly mounted on one end face side of an inner ring that is mounted on a drive shaft side to thereby rotate together therewith. The seal (6) has a resilient material (62) mounted at a distal end of a metal ring (61), and is fixedly mounted on one end face side of an outer ring (3) fixed to a vehicle body side which one end face side corresponds to the one end face side of the inner ring. The seal (6) encompasses the pulser ring (4) inside thereof. The resilient material (62) of the seal (6) is brought into close and slidable contact with an outer circumferential surface of a drive shaft (DS). The pickup sensor (5) is supported by the metal ring (61).

Description: BACKGROUND OF THE INVENTION The present invention relates to a wheel bearing device for an automobile, and more particularly to a wheel bearing device having incorporated therein a mechanism that detects the number of rotations of a wheel of the automobile. In an automobile equipped with an anti-skid braking system (ABS), it is necessary to detect the number of rotations of the wheels which changes moment by moment. A typical mechanism for detection of the number of rotations of the wheel is made up of a pulser ring having recessed and protruded teeth formed in an outer circumferential surface or a side thereof at a certain pitch, and a pickup sensor disposed so as to confront the recessed and protruded teeth for detection thereof. A mechanism for detecting the number of rotations of the wheels of an automobile like the one described above is, as seen from a cross-sectional view illustrated in Fig. 2, incorporated in a wheel bearing device. In this example, an inner ring 21 is fixedly mounted to an axle S and acts as a fixed ring, and an outer ring 23, which is made to freely rotate relative to the inner ring 21 via rolling members, is fixedly mounted over a hub (not shown) of a wheel and acts as a rotating ring. In addition, a pulser ring 24 is mounted on the outer ring 23, i.e. the rotating ring, to thereby rotate together with the wheel. A pickup sensor 25 is supported on a fixed portion of the vehicle body via a carrier 26 and disposed so as to confront the pulser ring 24. A sealing member 24a made from a rubber or the like is fixedly mounted on a radially innermost circumferential edge of the pulser ring 24, so that the sealing member 24a is brought into abutment with an outer circumferential surface of the inner ring 21 to achieve the sealing of the bearing. In addition, the pulser ring 24 and the pickup sensor 25 are sealed by a labyrinth seal 27 fixedly mounted on the side of the axle S. In the wheel bearing device having incorporated therein the mechanism for detecting the number of rotations of the wheel of an automobile as described above, although the seal 27 is mounted on the side of the axle S in an attempt to seal the pulser ring 24 and the pickup sensor 25, a gap G is still formed between the axle S or the seal 27 and each of the pulser ring 24 and the pickup sensor 25, which permits foreign matters to enter into the inside of the seal and adhere to the pulser ring 24 and the pickup sensor 25. This may deteriorate the performance of detecting the number of rotations. Another attempt to provide a wheel bearing device with a mechanism for detecting the number of rotations of the wheel, according the preamble of claim 1, is known from US 5,567,058. This device comprises an outer ring fixed to a vehicle body side, an inner ring rotatably supported by the outer ring and mounted on a drive shaft as well as a tone wheel, the rotations of which are counted by a sensor. Although a seal assembly is employed in the wheel bearing device of US 5,567,058, this seal is mostly a labyrinth seal as described above with respect to Fig. 2. Therefore, a gap remains at the tone wheel, into which dirt or moisture may enter. Another disadvantage associated with the wheel bearing device of US 5,567,058 is that moisture or dirt are not prevented from entering into a gap between the hub of the wheel and the drive shaft. This may eventually lead to the development of rust. SUMMARY OF THE INVENTION The present invention was made in view of these circumstances, and an object of the invention is to provide a wheel bearing device having a mechanism for detecting the number of rotations of a wheel of an automobile that can securely prevent the adherence of foreign matters to the pulser ring and the pickup sensor, thereby eliminating a deterioration in performance to detect the number of rotations of the wheel. With a view to fulfilling the above object, the present invention provides a wheel bearing device with the features of claim 1, i.e. comprising an outer ring fixed to a vehicle body side, and an inner ring that is rotatably supported by the outer ring via rolling bodies and that is mounted on a drive shaft side so as to rotate together therewith. In the device, a pulser ring is fixedly mounted on one end face side of the inner ring, and a seal in which an annular resilient material is mounted at a distal end of a metal ring is fixedly mounted at a proximal end thereof on one end face side of the outer ring which corresponds to the one end face side of the inner ring. The seal is mounted in such a manner that it encompasses the pulser ring and that the resilient material disposed at the distal end of the seal is arranged in tight contact with and slidable relative to an outer circumferential surface of a drive shaft. A pickup sensor is mounted on the metal ring in such a manner as to be opposed to the pulser ring. To achieve the stated object, the present invention adopts such an arrangement as to sealingly house the pulser ring and the pickup sensor. That is, the pulser ring is fixed to one end face side of the inner ring acting as a rotating ring, while the seal in which a resilient material such as a vulcanized rubber is mounted on the distal end of the metal ring is mounted on the one end face side of the outer ring acting as a fixed ring which one end face side corresponds to the one end face side of the inner ring. The resilient material is arranged in tight contact with and slidable relative to the outer circumferential surface of the drive shaft. The pickup sensor is mounted on the metal ring. This arrangement makes it possible to sealingly house the pulser ring and the pickup sensor on the axle side. BRIEF DESCRIPTION OF THE DRAWINGS In the accompanying drawings: Fig. 1 is a cross-sectional view showing arrangement according to an embodiment of the present invention, and Fig. 2 is a cross-sectional view showing an example of a typical arrangement of a wheel bearing device having incorporated therein a mechanism for detecting the number of rotations of a wheel of an automobile. DESCRIPTION OF THE PREFERRED EMBODIMENT Fig. 1 is a cross-sectional view of an embodiment of the present invention. An inner ring 1 is press-fitted and thus fixed to an outer circumference of a shaft portion of a hub H that is integrally mounted on a distal end of a drive shaft DS, so that the inner ring 1 rotates together with the drive shaft DS. An outer ring 3 rotatably supports the inner ring 1 via rolling members 2, and is fixed to a vehicle body side, for instance, to a knuckle or the like. A pulser ring 4 is fixedly mounted on one end face side of the inner ring 1 (on a side of the inner ring 1 opposite from the axial end of the drive shaft DS), and a seal 6 is fixedly mounted on one end face side of the outer ring 3 which corresponds to the one end face side of the inner ring 1. In addition, a pickup sensor 5 is disposed inwardly of the seal 6 so as to be opposed to the pulser ring 4. Moreover, a bearing seal 8 is mounted on the other end face side of the inner ring 1 and outer ring 3. The seal 6 is constituted by a metal ring 61 that is fixed to the outer ring 3 at a proximal end thereof, and an annular rubber 62 that is mounted on a distal end of the metal ring 61. The metal ring 61 has on a side of a proximal end thereof a cylindrical portion 61a that is fixedly fitted over the outer circumferential surface of the outer ring 3, and a tapered portion 61b extending from the cylindrical portion 61a toward a side of a distal end of the metal ring in such a manner that the diameter thereof gradually decreases. The metal ring 61 further has a bent portion 61c formed at a distal end of the tapered portion 61b in such a manner as to protrude inwardly therefrom. The annular rubber 62 is fixedly mounted on an inner circumference of the bent portion 61c. This rubber 62 is brought into close contact with the outer circumferential surface of the drive shaft DS but permitted to slidably move with respect to the outer circumferential surface of the drive shaft DS. The pickup sensor 5 is fixedly supported to the metal ring 61 via a carrier 7 that penetrates through and is fixed to the metal ring 61. The carrier 7 is formed into a pipe-like shape and a lead wire from the pickup sensor 5 is passed through the inside of the carrier 7 to be taken out of the device. In the arrangement according to the embodiment of the present invention, the pulser ring 4 and the pickup sensor 5 are both sealingly located within an annular space defined by the drive shaft DS, a bearing including the inner ring 1, the rolling members 2, the outer ring 3 and the bearing seal 8, and the seal 6. The external foreign matters never enter into the annular space. Further, since the end face of the bearing where the pulser ring 4 is mounted is sealingly housed by the seal 6, there is no need to mount another bearing seal at that location. Note that the present invention is not limited to the embodiment described above. For instance, any configuration or arrangement may be adopted as the metal ring 61 of the seal 6 as far as the proximal end of the metal ring is mounted on the fixed ring, and the distal end of the metal ring has the resilient material brought into a tight and slidable contact with the drive shaft DS so that the seal 6 as a whole creates a space for sealingly housing the pulser ring and the pickup sensor therein. As has been described heretofore, according to the present invention, the arrangement is adopted in which the pulser ring fixed to the rotating ring side so as to rotate together with the wheel and the pickup sensor disposed so as to be opposed to the pulser ring are sealed by the seal that is mounted on the fixed ring at the proximal end thereof and that supports at the distal end thereof the resilient material such as a rubber which is brought into close contact with and slidable relative to the outer circumferential surface of the drive shaft. Consequently, the penetration of foreign matters from the outside into the portion where the pulser ring and the pickup sensor are mounted can securely be prevented, thereby making it possible to restrain the deterioration of the performance to detect the number of rotations of a wheel of an automobile, which may be caused due to the adherence of such foreign matters to the pulser ring and the pickup sensor.

Claims: A wheel bearing device comprising: an outer ring (3) fixed to a vehicle body side, an inner ring (1) rotatably supported by said outer ring (3) through rolling members (2) and mounted on a drive shaft side (DS) so as to rotate together therewith, a pulser ring (4), and a seal (6) including a metal ring (61) and an annular resilient member (62), a proximal end (61 a) of said metal ring (61 ) being fixedly mounted on one end face side of said outer ring (3) corresponding to one end face side of said inner ring (1), said annular reresilient member (62) being mounted on a distal end (61 c) of said metal ring (61), wherein said pulser ring (4) is encompassed by said seal (6), and wherein a pickup sensor (5) is supported by said metal ring (61) to be opposed to said pulser ring (4), characterized by the pulser ring (4) being fixedly mounted on one end face side of said inner ring (1), and by said resilient member (62) being in tight and slidable contact with an outer circumferential surface of the drive shaft (DS). A wheel bearing device according to claim 1, wherein saidpulser ring (4) and said pickup sensor (5) are disposed within an annular sealed space defined by said outer ring (3) said rolling member (2), said inner ring (1), said drive shaft (D5) and said seal (6). A wheel bearing device according to claim 1, wherein said proximal end of said metal ring (61) has a cylindrical portion (61a) fixedly fitted over an outer circumference of said outer ring (3), and a portion (61b) of said metal ring (61) extending from said proximal end to said distal end is conical. A wheel bearing device according to claim 1, wherein said annular resilient member (62) includes a rubber. A wheel bearing device according to claim 1, wherein said seal (6) is bridged between said outer ring (3) and said outer circumferential surface of said drive shaft (DS).

Inventors: MORIMURA NAOKI, MORIMURA, NAOKI, Morimura, Naoki, c/o Koyo Seiko Co., Ltd.
Applicants: KOYO SEIKO CO, KOYO SEIKO CO., LTD.
Application year: 1999
Main classification: B60C23
IPC codes: F16C19, B60C23, G01P3, B60B35