Bearing for a vehicle axle, incorporating a sensor

Abstract: A bearing device (10) for a vehicle axle has an outer ring (12), two connected inner rings (11) and rollers (13). The outer ring has a mounting flange (12d) at the middle in the axial direction on an outside circumference surface thereof and a stepped hole (12a) open through radially at approximately the middle in the axial direction thereof. A pulser ring (18) is mounted at the middle in the axial direction of the two connected inner rings on outside circumference surfaces of the two connected inner rings. A rotation sensor (19) consists of a detecting member (19a) and a mounting member (21) vertical to the detecting member. The detecting member consists of a small end portion (19b) and a large middle portion (19c). The detecting member is inserted in the stepped hole (12a), so that the end portion opposes the pulser ring (18). A face of the mounting member (21) on a chassis bearing installation member side is positioned near the center line of the middle portion.

Description: BACKGROUND OF THE INVENTION The present invention relates to a bearing device for a vehicle axle characterized by an improved mounting structure for a rotation sensor. As shown in Figs. 7 and 8, a conventional bearing device for a vehicle axle has rolling elements 6 arrayed between an outer ring 2 and inner rings 5, through which passes an axle 3 and to which is mounted a pulser ring 4. A detecting member 7a of a rotation sensor 7 is inserted into an insertion hole 2a provided radially in the outer ring 2 so that the end of the detecting member 7a opposes the pulser ring 4, and a mounting member 9 of the rotation sensor 7 is secured to the outside surface of the outer ring 2 by bolts 8. The outer ring 2 is fit to the fitting hole 1a in the bearing mounting member i.e. knuckle 1 on the chassis, and a mounting flange 2b of the outer ring 2 is fixed to a face 1b of the knuckle 1 by bolts (not shown in the figures). By detecting a rotational velocity of the axle 3 by means of the rotation sensor 7 and the pulser ring 4, an antilock brake control system can be provided in the vehicle. It is to be noted that there is a terminal box 7c fixed to the mounting member 9. However, because the axle bearing device as thus described has a mounting flange 2b at approximately the middle in the axial direction on the outside surface of the outer ring 2 and the insertion hole 2a open through in the radial direction at approximately the middle in the axial direction on the outside surface of the outer ring 2, when the outer ring 2 mounting flange 2b is fixed to the end face 1b of the knuckle 1, the center line "c" of the insertion hole 2a is positioned near the end face 1b of the knuckle 1. As a result, the face 9a on the knuckle 1 side of the mounting member 9 of the rotation sensor 7 interferes by dimension "S" with the end face 1b of the knuckle 1, making it impossible in practice to secure the mounting member 9 of the rotation sensor 7 to the outer ring 2. This problem can be resolved by, for example, shifting the face 1b of the knuckle 1 in the axial direction by an amount equal to dimension S to prevent this interference. However, there are cases in which the position of the face 1b cannot be shifted due to the construction of the knuckle 1. Another way to avoid this interference is to make the mounting member 9 and the detecting member 7a smaller so there is no interference with the face 1b of the knuckle 1. However, this requires the diameter "d" of the detecting member 7a to be made extremely small, decreasing the detection performance of the rotation sensor. Furthermore, another method is to offset the face 9a of the mounting member 9 by dimension "S" in the axial direction to the detecting member 7a in the direction away from the end face 1b of the knuckle 1 to prevent any interference. However with this method the overlap of the detecting member 7a and the mounting member 9 is width "W", becoming narrower, and the connection of the detecting member 7a and the mounting member 9 is thus weakened. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a bearing device for a vehicle axle having a strong continuing between a detecting member and a mounting member which does not require the position of the mounting flange of an outer ring to be shifted or the size of the rotation sensor to be decreased and still maintains a sufficient overlap between the detecting member and the mounting member. In order to attain the above object, a bearing device for a vehicle axle of the present invention comprises an outer ring having a mounting flange at approximately the middle in the axial direction of the outer ring on an outside circumference surface of the outer ring for mounting the bearing device to an end surface of a chassis bearing installation member, and a stepped hole open through radially at approximately the middle in the axial direction, said stepped hole consisting of a small diameter portion and a large diameter portion; an inner ring means through which an axle passes; a pulser ring which is mounted at approximately the middle in the axial direction of the inner ring means on an outside circumference surface of the inner ring means; rolling elements positioned between the outer ring and the inner ring means; and a rotation sensor comprising a detecting member inserted in the stepped hole in the outer ring and a mounting member orthogonally extending from the detecting member and secured to an outside surface of the outer ring; said detecting member having an end portion opposite the pulser ring and inserted in the small diameter portion and a middle portion continuous to both the end portion and the mounting member, having a diameter greater than that of the end portion, and inserted in the larger diameter portion, and the mounting member being placed over a semicircular part of the middle portion such that its axially directed face is positioned near the center line of the middle portion and does not interfere with the end face of the chassis bearing installation member positioned. The end and middle portions of the detecting member of the rotation sensor can be positioned on the same axis. Alternatively, the center line of the middle portion can be offset with respect to the center line of the end portion of the detecting member towards the mounting member side. In addition, it is preferable to form a concave on the top of the middle portion of the rotation sensor on a side not continuous to the mounting member. The bearing device functions as follows. The detecting member of the rotation sensor is inserted into the stepped hole in the outer ring, and the mounting member is secured to the outside face of the outer ring. Then, the outer ring is set into a fitting hole in the bearing installation member on the chassis, and the mounting flange is secured to the end face of the bearing mounting member. At this time because the end of the mounting member on the bearing installation member side is positioned near the center line of the middle portion of the detecting member of the rotation sensor, the end of the mounting member does not interfere with the end of the bearing installation member. Furthermore, because the diameter of the middle portion of the detecting member of the rotation sensor is large, the overlap of the detecting member and the mounting member increases. Also, when the end and middle portions are on the same axis, processing is easier, and when offset, the width of continuing area between the mounting member and the middle portion of the detecting member is greater. Moreover, if a concave is formed on the top of the middle portion of the detecting member on the side not continuous to the mounting member, the top surface of the middle portion of the detecting member does not interfere with the inside circumference surface of the fitting hole in the bearing installation member. BRIEF DESCRIPTION OF THE DRAWINGS The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by the way of illustration only, and thus are not limitative of the present invention, and wherein: Fig. 1 is a sectional view of a bearing device for a vehicle axle according to a first embodiment of the present invention; Fig. 2 is a side view of the bearing device in Fig. 1; Fig. 3 is an enlarged view of the essential elements in Fig. 1; Fig. 4 is a sectional view of a bearing device for a vehicle axle according to a second embodiment of the present invention; Fig. 5 is a side view of the bearing device in Fig. 4; Fig. 6 is a sectional view of a bearing device for a vehicle axle according to a third embodiment of the present invention; Fig. 7 is a sectional view of a conventional bearing device; and Fig. 8 is a side view of the bearing device in Fig. 7. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Before the description of the present invention proceeds, it is to be noted that like parts are designated by like reference numerals throughout the accompanying drawings. As shown in Figs. 1 and 2, a hub unit for a vehicle wheel i.e. bearing device 10 for a vehicle axle in the first embodiment of the present invention has plural rows of rollers (rolling elements) 13 between connected inner rings 11 and an outer ring 12. The rollers 13 are held by retainers 14, and the area in which the rollers 13 are present is sealed by oil seals 15. The inside circumferences of the inner rings 11 are fit to an axle 16. Three mounting flanges 12d are provided at equidistant positions around the outside circumference of the outer ring 12 at approximately the middle in the axial direction. As shown in detail in Fig. 3 (wherein the retainers 14 and oil seals 15 are omitted), there is a stepped hole 12a passing radially through the outer ring 12 at approximately the middle in the axial direction of the outside surface of the outer ring 12. The stepped hole 12a consists of a large diameter portion 12b on the outside circumference side, and a small diameter portion 12c on the inside circumference side. Both the large diameter portion 12b and the small diameter portion 12c are concentric to center line "c1". The outer ring 12 is fit from the axial direction into the fitting hole 17a provided in a bearing installation member i.e. knuckle 17 on a chassis side until the mounting flanges 12d (see Fig. 2) contact the end face 17b of the knuckle 17, and is fixed by bolts (not shown in the figures) to the end face 17b of the knuckle 17. A pulser ring 18 made of magnetic materials is mounted at a position between the rollers 13 on the outside circumferences of the inner rings 11 at approximately the middle in the axial direction of the connected inner rings 11. The rotation sensor 19 consists of a detecting member 19a and a mounting member 21 orthogonally extending to this detecting member 19a, and the detecting member 19a is inserted to the stepped hole 12a in the outer ring 12 from the outside circumference side of the outer ring 12. The detecting member 19a consists of a small diameter end portion 19b on the pulser ring 18 side and a large diameter middle portion 19c on the mounting member 21 side; the center lines "c1" of the end portion 19b and the middle portion 19c are on the same axis, the diameter "d1" of the end portion 19b is set to enable the end portion 19b to be inserted in the small diameter portion 12c of the stepped hole 12a, and the diameter "d2" of the middle portion 19c is set to enable the middle portion 19c to be inserted into the large diameter portion 12b of the stepped hole 12a. In the detecting member 19a are housed a magnetic resistance element and a permanent magnet as not shown in figures, and the tip of the end portion 19b opposes the pulser ring 18 with a predetermined gap therebetween. It is to be noted that the diameter "d1" of the end portion 19b of the detecting member 19a is approximately equal to the diameter "d" of the conventional detecting member 7a shown in Figs. 7 and 8. An annular channel 19d is provided in the outside circumference surface of the middle portion 19c of the detecting member 19a, and an O-ring 20 is fitted into this annular channel 19d to seal the gap to the large diameter portion 12b of the stepped hole 12a. The mounting member 21 of the rotating sensor 19 is placed over one side of the top of the middle portion 19c of the detecting member 19a, specifically over a semicircular top surface 19e, so that the face 21a on the knuckle 17 side of the mounting member 21 is near the center line "c" of the middle portion 19c, and the mounting member 21 is secured by bolts 22 to the flat outside surface 12e of the outer ring 12. The lead wire 23 of the rotation sensor 19 is conducted to the outside through the inside of the mounting member 21. In addition, a shallow stepped concave 19f is formed on the top of the middle portion 19c of the detecting member 19a of the rotation sensor 19 on the side which is not continuous to the mounting member 21. A bearing device constructed as described hereinabove comprises a pulser ring 18, rollers 13, retainers 14, and oil seals 15 between an outer ring 12 and inner rings 11 with the detecting member 19a of the rotation sensor 19 inserted to a stepped hole 12a in the outer ring 12 and the mounting member 21 fixed by bolts 22 to the outside surface 12e of the outer ring 12. The outside circumference surface of the outer ring 12 is fit into the fitting hole 17a in the knuckle 17, the mounting flanges 12d of the outer ring 12 are set against the end face 17b of the knuckle 17, and the mounting flanges 12d are fixed by bolts thereto. Then, because the face 21a of the mounting member 21 on the knuckle 17 side is positioned near the center line "c1" of the middle portion 19c of the detecting member 19a of the rotation sensor 19, the face 21a of the mounting member 21 does not interfere with the end face 17b of the knuckle 17. Furthermore, because the diameter of the middle portion 19c of the detecting member 19a of the rotation sensor 19 is larger than that of the end portion 19b, the width "W" of the area continuing between the middle portion 19c and the mounting member 21 is greater, and the connecting portion of the detecting member 19a and the mounting member 21 are stronger. Furthermore, because the middle portion 19c and the end portion 19b of the detecting member 19a of the rotation sensor 19 are concentric, it is easy to process the detecting member 19a and the stepped hole 12a. In addition, because there is a stepped concave 19f on the top of the middle portion 19c of the detecting member 19a of the rotation sensor 19, the top of the middle portion 19c of the detecting member 19a does not interfere with the inside circumference surface of the fitting hole 17a, and fitting the outer ring 12 into the fitting hole 17a can be completed more smoothly. A hub unit 30 for a vehicle wheel according to a second embodiment of the present invention is shown in Figs. 4 and 5 wherein parts and assemblies which are identical to those in the first embodiment described hereinabove are identified by like reference numerals and further description thereof is hereinbelow omitted. In this second embodiment, the center line "c2" of the middle portion 19c is offset from the center line "c1" of the end portion 19b of the detecting member 19a of the rotation sensor 19 towards the side on which the mounting member 21 is present by a distance "1". The mounting member 21 is positioned on the semicircular top surface 19e of the middle portion 19c so that the face 21a on the knuckle 17 side is positioned near the center line "c2" of the offset middle portion 19c, and the mounting member 21 is secured to the flat outside surface 12e of the outer ring 12 by bolts 22. A terminal box 19g of the rotation sensor 19 is mounted to the mounting member 21. In this second embodiment, too, because the end face 21a of the mounting member 21 on the knuckle 17 side is positioned near the center line "c2" of the middle portion 19c of the detecting member 19a, the end face 21a of the mounting member 21 does not interfere with the end face 17b of the knuckle 17. Furthermore, because the diameter of the middle portion 19c of the detecting member 19a of the rotation sensor 19 is larger than that of the end portion 19b and the middle portion 19c is offset, the width of the overlapping area between the middle portion 19c and the mounting member 21 is even greater than that in the first embodiment, and the connection of the detecting member 19a to the mounting member 21 is even stronger. Shown in Fig. 6 is a third embodiment, which differs from the second embodiment described above in that the continuing portion between the end portion 19b and the middle portion 19c of the detecting member 19a of the rotation sensor 19 is tapered, and a tapered seat 12f is provided between the large diameter portion 12b and the small diameter portion 12c of the stepped hole 12a. Thus, insertion of the detecting member 19a of the rotation sensor 19 to the stepped hole 12a of the outer ring 12 can be completed more easily. In addition, each of the above embodiments has the two inner rings. But, it is to be noted that the two inner rings can be replaced with only one inner ring. As will be known from the above descriptions of the preferred embodiments, the middle portion of the detecting member of the rotation sensor inserted to the stepped hole in the outer ring has a larger diameter than the end portion of the detecting member, and the end face of the mounting member connecting to this middle portion on the bearing installation member side is positioned near the center line of the middle portion of the detecting member in a bearing device according to the present invention. Therefore, because the end face of the mounting member does not interfere with the face of the bearing installation member on the chassis side, it is not necessary to offset the position of the mounting flange of the outer ring in the axial direction or to decrease the diameter of the detecting member of the rotation sensor as with conventional methods of avoiding structural interference. Furthermore, because the diameter of the middle portion of the detecting member of the rotation sensor is larger than that of the end portion, the overlap between the detecting member and the mounting member is wider and this overlapping member is stronger. Moreover, processing of the stepped hole is easier if the end and middle portions of the detecting member of the rotation sensor are concentrically positioned. Furthermore, if the center line of the middle portion is offset with respect to the center line of the end porion of the detecting member of the rotation sensor to the side on which the mounting member is present, the width of the continuing portion between the mounting member and the middle portion of the detecting member of the rotation sensor is even greater, and this continuing portion is even stronger. In addition, if a concave is formed in the top of the middle portion of the detecting member of the rotation sensor, the top surface of the middle portion of the detecting member does not interfere with the inside circumference of the fitting hole in the hearing installation member, and assembly of the outer ring into the fitting hole can be completed smoothly. The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.

Claims: A bearing device for a vehicle axle comprising: an outer ring (12) having a mounting flange (12d) at approximately the middle of its axial length on its outside circumference surface for mounting the bearing device (10) to an end surface of a chassis installation member (17), and a stepped hole (12a) open through radially at approximately the middle of said axial length, said stepped hole (12a) consisting of a small diameter portion (12c) and a large diameter portion (12b); an inner ring means (11) through which an axle passes; a pulser ring (18) which is mounted at approximately the middle of the axial length of the inner ring means (11) on an outside circumference surface thereof; rolling elements (13) positioned between the outer ring (12) and the inner ring means (11); and a rotation sensor (19) comprising a detecting member (19a) inserted in the stepped hole (12a) in the outer ring (12) and a mounting member (21) extending orthogonally from the detecting member (19a) and secured to an outside surface of the outer ring (12); said detecting member (19a) having an end portion (19b) opposite the pulser ring (18) and inserted in said small diameter portion (12c) and a middle portion (19c) continuous to both the end portion (19b) and the mounting member (21), having a diameter (d2) greater than that (d1) of the end portion (19b), and inserted in said larger diameter portion (12b), characterized in that said mounting member (21) is placed over a semicircular part of the top surface (19e) of said middle portion (19c) such that the axially extending face (21a) of the mounting member (21) on the chassis bearing installation member side is positioned near the center line (c1) of the middle portion (19c). A bearing device according to Claim 1 wherein the end and middle portions (19b,19c) of the detecting member (19a) of the rotation sensor (19) are positioned concentrically. A bearing device according to Claim 1 wherein the center line (c2) of the middle portion (19c) is offset from the center line (c1) of the end portion (19b) of the detecting member (19a) of the rotation sensor (19) towards the side on which the mounting member (21) is placed. A bearing device according to Claim 1 wherein a stepped concave (19f) is formed on the top of the middle portion (19c) of the rotation sensor (19) on the side which is not continuous to the mounting member (21).

Inventors: NAKAYAMA KATSUHIKO, NAKAYAMA, KATSUHIKO
Applicants: KOYO SEIKO CO, KOYO SEIKO CO., LTD.
Application year: 1991
Main classification: G01P3
IPC codes: F16C19, G01P3, B60T8, F16C41