WO2012176012A1

WO2012176012A1 - Bearing assembly for an automotive vehicle with sensor unit

Info

Publication number: WO2012176012A1
Application number: PCT/IB2011/001774
Authority: WO
Inventors: Franck Landrieve
Original assignee: Aktiebolaget Skf
Priority date: 2011-06-23
Filing date: 2011-06-23
Publication date: 2012-12-27

Abstract

This bearing assembly for an automotive vehicle comprising a fixed element (2), an element (4) rotatable with respect to the fixed element (2) around a longitudinal axis (Χ-Χ') of said fixed element (2), a bearing (6), in particular a rolling bearing including a fixed ring (60) fast with the fixed element (2), and a rotatable ring (62) fast with the rotatable element (4), a sensor unit (10) for sensing the angular position of the rotating element (4) with respect to the fixed element (2), and means (30, 310) for processing and transmitting the data delivered by the sensor unit (10). The sensor unit (10) includes means to generate an electrical current for electrically powering the means (30, 310) for processing and transmitting the data delivered by the sensor unit (10).

Description

BEARING ASSEMBLY FOR AN AUTOMOTIVE VEHICLE WITH SENSOR UNIT

TECHNICAL FIELD OF THE INVENTION

The present invention concerns a bearing assembly, in particular of the rolling type, for an automotive vehicle, such as a motorcycle.

BACKGROUND OF THE INVENTION

On automotive vehicles, such as two wheelers, the wheels are generally equipped with tachymeter bearings for sensing the rotation speed of the wheels, as known from, from example, US-B-5 309 094.

The speed data are generally transmitted via a cable linking the tachymeter bearing and the dashboard. This induces mounting issues and reduces the moving abilities of the front wheel of the motorcycle. Radio signals can be used to overcome this issue. Emitting signals need further electrical energy, while the available space near the wheels of a motorcycle is reduced. Known tachymeter bearings also need electrical energy to perform processing of the data delivered by the angular position sensor which belongs to the tachymeter bearing. This induces the need for an electric energy storage system in the vicinity of the axle. As available space is reduced on motorcycles, such a storage system cannot be easily designed.

SUMMARY OF THE INVENTION

The aim of the invention is to provide a new bearing assembly, in which the tachymeter bearing is mounted inside the hub of the wheel and does not need any external energy storage system for processing angular position data and transmitting speed data to the dashboard of the vehicle.

To this end, the invention concerns a bearing assembly for an automotive vehicle, such a motorcycle, comprising a fixed shaft, a wheel hub rotatable with respect to the shaft around a longitudinal axis of said shaft, a bearing, and in particular a rolling bearing including an inner ring fast with the shaft, and an outer ring fast with the hub, a sensor unit for sensing the angular position of the hub with respect to the shaft, and means for processing and transmitting the data delivered by the sensor unit. This rolling bearing assembly is characterized in that the sensor unit includes means to generate an electrical current for electrically powering the means for processing and transmitting the data delivered by the sensor unit.

Thanks to this invention, the electrical energy needed to process the data delivered by the sensor unit is generated by the sensor unit itself, avoiding the need of an external energy storage system and drawbacks relating to the design of the housing for such a storage system.

According to further aspects of the invention, which are advantageous but not compulsory, such a bearing assembly may incorporate one or several of the following features:

- Some of the means to generate an electrical current extend in a limited angular sector of an annular gap extending between the rotating element and the fixed element.

- The fixed element is a shaft of a fork of a motorcycle, and wherein the rotatable element is a wheel hub of said motorcycle.

- The sensor unit includes a coder element fast with the rotatable ring and a sensing element fast with the fixed ring.

- The sensing element, the means for processing and transmitting the data delivered by the sensor unit and some means for generating an electrical current are mounted on a printed circuit board fast in rotation with the shaft.

- The printed circuit board comprises means to transmit parameters representing the rotation speed of the hub to a reception device.

- The means to transmit parameters include an antenna connected to the printed circuit board and extending partially outside the hub along the longitudinal axis of the shaft.

- The bearing and the sensor unit are mounted on a sleeve which is mounted on the shaft and whereas the antenna is housed in a groove realized on an outer peripheral surface of the sleeve along the longitudinal axis of the shaft.

- The means for generating an electrical current include an induction sensing element and whereas an electrical current delivered by the induction sensing element is used for electrically powering the means for processing and transmitting the data delivered by said sensing element.

- The induction sensing element comprises a single magnet and a coil.

- The induction sensing element comprises two magnets, with parallel direction of polarity, and a coil.

- The sensor unit includes a piezoelectric sensing element, and whereas electrical currents delivered by the piezoelectric sensing element are used for electrically powering the means for processing and transmitting the data delivered by said sensing element.

- The rotatable ring is the outer ring of the bearing, and wherein the fixed ring is the inner ring of the bearing.

- The rotatable ring is the inner ring of the bearing, and wherein the fixed ring is the outer ring of the bearing. - The bearing is of the rolling type.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexed figures, as an illustrative example. In the annexed figures:

figure 1 is an exploded perspective view of a rolling bearing assembly according to a first embodiment of the invention;

figure 2 is a sectional view of a portion of the rolling bearing assembly of figure 1 , along a longitudinal plane;

- figure 3 is a perspective view, at a larger scale, of detail III on figure 1 of a portion of a sensing element belonging to the assembly of figures 1 and 2;

Figure 4 is a view of a portion of the sensing element of figure 4, from a different angle, a flux concentrator being remote from the sensing element ;

figure 5 is a partial sectional view of the rolling bearing assembly of figure 2, along plane V on figure 2, in a first configuration ;

figure 6 is a view similar to figure 5, for a second configuration;

figure 7 is a view similar to figure 1 for a rolling bearing assembly according to a second embodiment of the invention;

figure 8 is a perspective view, at a larger scale, of detail VIII on figure 7, of a portion of a sensing element belonging to the assembly of figure 7;

figure 9 is a sectional view, along a longitudinal plane, of the rolling bearing assembly of figure 7;

figure 10 is a partial sectional view, along plane X on figure 9, of the rolling bearing assembly of figure 9, in a first configuration;

- figure 1 1 is a sectional view similar to figure 10, for a second configuration;

figure 12 is a sectional view similar to figures 2 and 9, of a rolling bearing assembly according to a third embodiment of the invention;

figure 13 is a perspective view of a coder element belonging to the rolling bearing assembly of figure 12.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

The rolling bearing assembly A represented on figure 1 is adapted to be mounted on an automotive vehicle, such as a motorcycle.

Assembly A comprises a shaft 2, adapted to be fixed to a non-shown fork of a motorcycle and a hub 4, adapted to be fast in rotation with a non-shown wheel of the motorcycle, so that it rotates with respect to shaft 2 along a longitudinal axis X-X' of shaft 2.

Rotation of hub 4 with respect to shaft 2 is allowed by a rolling bearing 6. Rolling bearing 6 comprises an inner ring 60, an outer ring 62 and rolling elements, such as balls 64. Inner ring 60 is fixed to a sleeve 8, which is mounted on shaft 2. Inner ring 60 is mounted on an outer peripheral surface 80 of sleeve 8 and positioned against a shoulder 82 of sleeve 8, which delimits peripheral surface 80 with respect to a peripheral surface 84, which has a greater outer diameter than peripheral surface 80.

Outer ring 62 is fast in rotation with hub 4 and mounted on an inner peripheral surface 40 of hub 4. An annular gap G extends between surfaces 40 and 84.

Rolling bearing assembly A is equipped with a sensor unit 10, adapted to detect or sense the angular position of hub 4 with respect to shaft 2 in order to determine the rotation speed of hub 4 and the speed of the motorcycle. Sensor unit 10 comprises a coder element 12 which includes an inner flux concentrator 100 and an outer flux concentrator 120 fast with a flux concentrator holder 130. Flux concentrator 100 and 120 are concentric rings respectively equipped with spaced respective teeth 101 and 121 distributed regularly around their circumferences. Teeth 101 and 121 extend parallel to axis X-X'. Teeth 101 of inner flux concentrator are angularly offset with respect to teeth 121 of outer flux concentrator 120. Holder 130 includes a first part 131 on which flux concentrators 100 and 120 are axially positioned, and a second part 132 fast with first part 131 , which comprises a positioning hole 133 for angularly position inner flux concentrator 100 and outer flux concentrator 120 with respect to each other. Each of flux concentrators 100 and 120 comprises a positioning pin 103 and 123 adapted to cooperate with positioning hole 133.

Coder element 12 of sensor unit 10 is fast in rotation with hub 4 thanks to a clipping member 135, extending from holder 130 along axis X-X', and fixed to outer ring 62.

Sensor unit 10 further includes an induction sensing element 20. Sensing element 20 is mounted on a printed circuit board (PCB) 30 which comprises means for processing and transmitting the data delivered by sensor unit 10. PCB 30 has a radial annular shape centered around axis X-X' and extends on an area axially facing coder element 12. On a first surface 301 of PCB 30 oriented towards coder element 12, sensing element 20 comprises a coil 201 in which a core 203 is inserted. Core 203 may be made of a ferromagnetic material such as ferrite, and has a cylindrical shape extending along an axis X201 perpendicular to axis X-X' and parallel to surface 301.

On a surface 303 of printed circuit board 30 opposed to surface 301 , sensing element 20 is equipped with a magnet 205, which has substantially the shape of a parallelepiped extending along a longitudinal axis X205 perpendicular to axis X201. Axis X205 joins the North and South Poles of magnet 205. Magnet 205 is positioned with respect to coil 201 so that magnet 205 and coil 201 form a cross, when viewed along axis X-X'. As magnet 205 is not visible on sectional plane V, it is represented in discontinuous lines on figures 5 and 6.

Magnet 205 is fast with printed circuit board 30 by two non-rotating flux concentrators 207 and 209, so that axis X205 is parallel to surface 303. Each of concentrators 207 and 209 comprises respective radially extending outer flux concentrating plates 2070 and 2090 and radially extending inner flux concentrating plates 2072 and 2092. Outer plates 2070 and 2090 extend parallel to axis X-X' towards coder elements 12 in the vicinity of an outer peripheral edge 305 of printed circuit board 30, radially outside this edge with respect to axis X-X'. Inner concentrating plates 2072 and 2092 extend parallel to axis X-X' towards coder element 12 in the vicinity of an inner peripheral edge 307 of printed circuit board 30, radially inside this edge with respect to axis X-X'.

Non-rotating flux concentrator 207 comprises a fastening plate 2074 on which the north pole N of magnet 205 is fixed. In the same way, non-rotating flux concentrator 209 comprises a fastening plate 2094 on which the south pole S of magnet 205 is fixed.

Sensing element 20 is housed into a circular sensing element holder 22, which is mounted on surface 84 of sleeve 8 and positioned against a stop 86 opposed to shoulder 82 along axis X-X'.

Printed circuit board 30 is equipped with components adapted to process data delivered by sensing element 20. For example, printed circuit board 30 can comprise microprocessors and memories. Printed circuit board 30 also comprises means to transmit, to a non-shown dashboard of the motorcycle, data delivered by sensing element 20 or calculated by the components of printed circuit board 30, generally parameters representative of the rotation speed of hub 4. To transmit such parameters, printed circuit board 30 can include a non represented radio signals emitter, and an antenna 310 connected to printed circuit board 30. Antenna 310 is housed in a groove 88 realized on surfaces 80 and 84 between stop 86 and an axial end 89 of sleeve 8 close to bearing 6. Antenna 310 extends partially outside a volume delimited by hub 4. This structure avoids blocking of radio signals by hub 4, which is generally metallic and may act as a faraday cage.

Rolling bearing assembly A works in the following way: while coder element 12 rotates with respect to sensing element 20, teeth 101 and 121 come close to concentrating plates 2070, 2072, 2090 and 2092. Teeth 101 and 121 extend on delimited angular sector and are angularly offset with respect to each other so as to achieve the two following configurations, which are obtained during a determined portion of a turn of coder element 12 with respect to sensing element 20.

In the first configuration represented on figure 5, a tooth 121 of outer flux concentrator 120 faces outer concentrating plate 2070 of flux concentrator 207 and an outer end 2030 of core 203 oriented opposite to axis X-X'. At the same time, outer concentrating plate 2090, opposed to plate 2070 with respect to outer core end 2030 faces mainly an empty space of outer flux concentrator 120. A tooth 101 of inner flux concentrator 100 faces an inner end 2032 of core 203 and the inner concentrating plate 2092 of non-rotating flux concentrator 209. At the same time, inner concentrating plate 2072 faces mainly an empty space of inner flux concentrator 100.

The respective angular extensions of teeth 101 and 121 and their relative angular offset permit that the north pole N of magnet 205 is magnetically connected to outer end 2030 via external plate 2070 and tooth 121 , while south pole S of magnet 205 is magnetically connected to inner end 2032 via inner plate 2092 and tooth 101 . These magnetic connections induce a magnetic field represented by line B1 on figure 5, which originates from north pole N, crosses core 203 along axis X201 from outer end 2030 to inner end 2032 and ends on south pole S. This magnetic field B1 induces an electrical potential difference between the ends of coil 201 and therefore an electrical current.

When the rotation of coder element 12 goes further, a second configuration, corresponding to a second relative position of coder element 12 and sensing element 20, is obtained. In this configuration represented on figure 6, the respective positions of teeth 101 and 121 with respect to concentrating plates of flux concentrators 207 and 209 are inverted with respect to the configuration of figure 5. In other words, a tooth 121 now faces outer end 2030 and outer concentrating plate 2092, while a tooth 101 faces inner end 2032 and inner concentrating plate 2072. This means that north pole N of magnet 205 is now connected to inner end 2032, while south pole S is connected to outer end 2030. The magnetic field obtained in this case is represented by line B2, on figure 6, which crosses core 203 from inner end 2032 to outer end 2030, in the opposite direction with respect to the configuration of figure 5. The induced electrical current passing in coil 201 is therefore inverted with respect to the one which passes in the configuration of figure 5.

The two previous configurations induce a high efficiency of induced electrical current generation. Between these two configurations, transient periods take place. The generation of successive alternating magnetic fields B1 and B2 induces an alternating electrical current passing in coil 201 . During a turn of coder element 12 with respect to sensing element 20, the configurations of figures 5 and 6 are repeated a predetermined number of times depending on the respective number of teeth 101 and 121.

The measurement of the frequency of this alternative current gives, via electronic processing taking into account the number of teeth 101 and 121 , the angular position of hub 4 with respect to shaft 2, and the rotation speed of hub 4. With further electronic processing implemented in the components of printed circuit board 30, the speed of the motorcycle can be determined and transmitted via antenna 310.

The electrical current obtained in coil 201 also provides electric energy for directly or indirectly operating the processing and transmitting means implemented on printed circuit board 30. Transducers can be used to obtain from the output current of coil 201 a direct current to be delivered to the electronic components of printed circuit board 30. Given that the electrical power needs of the electronic components of printed circuit board 30 are relatively low, for example below 10^"4 W, there is not a need for high electrical current generation. The electrical current generated in coil 201 is therefore sufficient to operate the processing and transmitting means. In other words, the tachymeter bearing formed by rolling bearing 6 and sensor unit 10 is autonomous, as it generates itself the electrical energy needed to process and transmit the data delivered by sensor unit 10. Besides, the relatively small space occupied by sensing element 20 allows mounting it in a limited angular sector of annular gap G and to improve the compactness of 10 and rolling bearing assembly A, by mounting sensing element 20 on PCB 30.

A second embodiment of the invention is represented on figures 7 to 1 1. Elements similar to the first embodiment have the same references and work in the same way.

An induction sensing element 45 is mounted on printed circuit board 30. Sensing element 45 comprises a central coil 451 extending along a radial axis X451. A core 453 is inserted in coil 451 along axis X451 . Core 453 is cylindrical shaped and is similar to core 203. Sensing element 45 further includes two magnets 455 and 457, which have a substantial parallelepiped shape extending along axes X455 and X457 parallel to axis X451. A first magnet 455 is positioned on the left of coil 451 on figures 10 and 1 1 and a second magnet 457 is positioned on the right of coil 451 . Core 453 has an outer end 4530 and an inner end 4532 oriented towards axis X-X'. Magnet 455 has its north pole N oriented towards outer end 4530 and its south pole S oriented towards inner end 4532 oriented towards axis X-X'. Magnet 457 has an inverted arrangement. Its north pole N is oriented towards inner end 4532 while its south pole S is oriented towards outer end 4530. A plate 459 made of a magnetic material magnetically connects the south pole S of magnet 455 to the north pole N of magnet 457. Magnets 455 and 457, coil 451 , core 453 and link plate 459 are housed in a casing 461 which is fast with printed circuit board 30 thanks to fastening means comprising pins 463 adapted to be inserted in holes 312 of PCB 30. Assembly A comprises a sensing element holder 22 in which printed circuit board 30 and sensing element 45 are mounted. Assembly A comprises also a coder element 50, which includes a single rotating flux concentrator 500. Flux concentrator 500 has teeth 502 similar to teeth 121 , which extend parallel to axis X-X' and so as to radially face outer end 4530 of core 453 while rotating. Flux concentrator 500 is fast in rotation with outer ring 62 thanks to a fastening edge 504. Printed circuit board 30 is equipped with the same type of components as in the first embodiment, including processing and transmitting means for the data delivered by sensor element 45. Printed circuit board 30 also comprises an antenna 310 adapted to emit radio signals for transmitting data.

In this embodiment, assembly A works in the following way: when flux concentrator 500 rotates with respect to sensing element 45, a first configuration corresponding to a first relative position of teeth 502 with respect to magnets 455 and 457 occurs. In this configuration represented on figure 10, a tooth 502 faces the north pole N of magnet 455 and outer end 4530 of core 453. As flux concentrator 500 is made of a magnetic material, this means that north pole N of magnet 455 is magnetically connected to outer end 4530, while inner end 4532 is magnetically connected to link plate 459. A magnetic field represented by line B3 on figure 10 therefore exists in coil 451 . Line B3 originates from north pole N of magnet 455 and crosses core 453 from outer ring 4530 to inner end 4532. This magnetic field B3 induces an electrical potential difference between the ends of coil 451 and therefore creates an electrical current passing in coil 451.

When the rotation of coder element 50 with respect to sensing element 45 goes further, a second configuration corresponding to a second relative position of coder element 50 with respect to sensing element 45 is obtained. In this configuration represented on figure 1 1 , a tooth 502 of flux concentrator 500 faces outer end 4530 and south pole S of magnet 457, while the north pole N of magnet 457 faces an empty space of flux concentrator 500.

Outer ring 4530 is therefore magnetically connected to the south pole S of magnet 457. As the south pole S of magnet 455 and the north pole N of magnet 457 are magnetically connected, magnet 455 and link plate 459 act as a north pole N together with the north pole N of magnet 457.

A magnetic field is therefore generated in coil 451. This magnetic field is represented by line B4 on figure 1 1 , which originates from a north pole formed by magnet 455, connects plate 459 and north pole N of magnet 457. Line B4 crosses core 453 from inner end 4532 to outer end 4530 and ends at the south pole S of magnet 457 via tooth 502. This provokes a potential difference between outer end 4530 and inner end 4532 and the generation of an induced electrical current in coil 451 . As the direction of the magnetic field B4 is inverted with respect to the direction of magnetic field B3, the electrical current obtained in the configuration of figure 1 1 is inverted with respect to the one obtained in the configuration of figure 10.

Thus, in the same way as in the first embodiment, rotation of coder element 50 with respect to sensing element 45 induces the generation of an induced alternative electrical current passing in coil 451. This electrical alternative current is processed in the same way as in the first embodiment in order to determine parameters representing the rotation speed of hub 4. These parameters are transmitted thanks to means implemented in printed circuit board 30. In the same way as in the first embodiment, this alternative current is used to electrically power the electronic components of printed circuit board 30. The structure of sensing element 45, which extends on a limited angular sector of annular gap G, improves the compactness of sensor unit 10 and assembly A.

A third embodiment is represented on figures 12 and 13. Elements similar to the embodiments of figures 1 to 1 1 have the same references and work in the same way.

In this embodiment, assembly A comprises a coder element 70 formed by a magnetic ring made by assembling permanent magnets 72 of alternating magnetic polarities. Coder element 70 is fast in rotation with outer ring 62.

Assembly A also comprises a piezoelectric sensing element 90, which is fast with shaft 2 and equipped with a piezoelectric sensor 900. Sensor 900 extends parallel to axis X-X' in idle configuration. Piezoelectric sensor 900 is fixed to a printed circuit board (PCB) 30. At its end opposed to PCB 30, piezoelectric sensor 900 is equipped with a magnet 904 adapted to face, along an axis perpendicular to an axis X-X', the alternated magnetic poles of magnets 72 of coder element 70.

When coder element 70 rotates with respect to sensing element 90, the passage of alternated poles in front of magnet 904 induces alternative displacements of magnet 904, as shown by double arrow A1 on figure 12.

The subsequent vibrations of piezoelectric sensor 900 induce the generation of an electrical current whose electrical characteristics are representative of the rotation speed of coder element 70.

Piezoelectric sensor is connected to a printed circuit board 30 on which means for processing and/or transmitting the data delivered by sensing element 90 are implemented. As in the previous embodiments, on printed circuit board 30, the electrical current delivered by sensor 900 is processed so as to determine the angular position of coder 70 and the rotation speed of hub 4 and data are transmitted thanks to antenna 310.

The electrical current generated by sensor 900 is used to electrically power the electric components with which the processing and the transmitting of the data delivered by sensing element 90 are performed.

As in the previous embodiments, piezoelectric sensing element 90 extends on a limited angular sector of annular gap G. This permits to mount it on PCB 30 and therefore to improve the compactness of sensor unit 10 and assembly A.

According to an alternative non-shown embodiment of the invention, inner ring 60 of rolling bearing 6 may be the rotating ring while outer ring 62 may be the fixed ring.

The invention can be implemented in any kind of bearing, for instance a rolling bearing, such as a ball bearing, or a plain bearing.

Claims

1. A bearing assembly (A) for an automotive vehicle, comprising:

a fixed element (2),

- an element (4) rotatable with respect to the fixed element (2) around a longitudinal axis (Χ-Χ') of said fixed element (2),

a bearing (6), including a fixed ring (60) fast with the fixed element (2), and a rotatable ring (62) fast with the rotatable element (4),

a sensor unit (10) for sensing the angular position of the rotatable element (4) with respect to the fixed element (2), and

means (30, 310) for processing and transmitting the data delivered by the sensor unit (10),

wherein the sensor unit (10) includes means (100, 120, 201 , 205, 500, 451 , 455, 457, 72, 900) to generate an electrical current for electrically powering the means (30, 310) for processing and transmitting the data delivered by the sensor unit (10).

2. Bearing assembly according to claim 1 , wherein some of the means (201 , 205, 451 , 457, 900) to generate an electrical current extend in a limited angular sector of an annular gap (G) extending between the rotatable element (4) and the fixed element (2).

3. Rolling bearing assembly according to one of the previous claims, wherein the fixed element is a shaft (2) of a fork of a motorcycle, and wherein the rotatable element is a wheel hub (4) of said motorcycle.

4. Bearing assembly according to one of the previous claims, wherein the sensor unit (10) includes a coder element (12; 50; 70) fast with the rotatable ring (62) and a sensing element (20; 45; 90) fast with the fixed ring (60).

5. Bearing assembly according to claim 4, wherein the sensing element (20; 45; 90), the means for processing and transmitting the data delivered by the sensor unit (10) and some means (201 , 205, 451 , 455, 457, 900) for generating an electrical current are mounted on a printed circuit board (30) fast in rotation with the shaft (2).

6. Bearing assembly according to claim 5, wherein the printed circuit board (30) comprises means (310) to transmit parameters representing the rotation speed of the hub

(4) to a reception device.

7. Bearing assembly according to claim 6, wherein the means to transmit parameters include an antenna (310) connected to the printed circuit board (30) and extending partially outside the hub (4) along the longitudinal axis (Χ-Χ') of the shaft (2).

8. Bearing assembly according to claim 7, wherein the bearing (6) and the sensor unit (10) are mounted on a sleeve (8) which is mounted on the shaft (2) and wherein the antenna (310) is housed in a groove (88) realized on an outer peripheral surface (80, 84) of the sleeve (8) along the longitudinal axis (Χ-Χ') of the shaft (2).

9. Bearing assembly according to one of the previous claims, wherein the means for generating an electrical current include an induction sensing element (20; 45) and wherein an electrical current delivered by the induction sensing element (20 ; 45) is used for electrically powering the means (30) for processing and transmitting the data delivered by said sensing element (20 ; 45).

10. Bearing assembly according to claim 9, wherein the induction sensing element (20) comprises a single magnet (205) and a coil (201 ).

1 1. Bearing assembly according to claim 10, wherein the induction sensing element

(45) comprises two magnets (455, 457), with parallel direction of polarity (N/S), and a coil (451 ).

12. Bearing assembly according to one of claims 1 to 8, wherein the sensor unit (10) includes a piezoelectric sensing element (90), and wherein electrical currents delivered by the piezoelectric sensing element are used for electrically powering the means (30) for processing and transmitting the data delivered by said sensing element.

13. Bearing assembly according to one of the previous claims, wherein the rotatable ring is the outer ring (62) of the bearing (6), and wherein the fixed ring is the inner ring

(60) of the bearing (6).

14. Bearing assembly according to one of the claims 1 to 12, wherein the rotatable ring is the inner ring (60) of the bearing (6), and wherein the fixed ring is the outer ring (62) of the bearing (6).

15. Bearing assembly according to any of the previous claim wherein the bearing (6) is of the rolling type, in particular a ball bearing.