SUCH UNIT AND A MOUNTING METHOD

TECHNICAL FIELD OF THE INVENTION

The invention concerns a sensor-bearing unit. The invention also concerns a mechanical system, for example a motorcycle axle, comprising at least one such sensor- bearing unit. The invention also concerns a mounting method of such sensor-bearing unit in such mechanical system. BACKGROUND OF THE INVENTION

Today, sensor-bearing units are commonly used in automotive, aeronautics and other technical fields. These units provide high quality signals and transmissions, while allowing integration in simpler and more compact mechanical systems.

Such a sensor-bearing unit generally comprises a bearing, an impulse ring and detection means facing the impulse ring. The impulse ring may comprise a target holder and a target including alternating north and south poles, whose number depends on bearing size and particular application. The impulse ring may be fixed to a rotating ring of the bearing, while detection means may be fixed to a non-rotating ring of the bearing or to another part supporting this non-rotating ring.

WO-A-2012 023 000 and WO-A-2012 023 001 describe examples of sensor-bearing units equipping a mechanical system, precisely a motorcycle axle. The non-rotating ring is mounted on a shaft fixed to a fork, while the rotating ring is mounted inside a hub supporting a wheel. The detection means are fixed to the fork by a flexible flange. However, compactness of the mechanical system and precision of the detection may be further improved.

SUMMARY OF THE INVENTION

The aim of the invention is to provide an improved sensor-bearing unit.

To this end, the invention concerns a sensor-bearing unit, comprising:

- a bearing including at least one non-rotating ring and at least one rotating ring movable in rotation around a rotation axis;

- an impulse ring and a sensor device for tracking the rotation of the rotating ring around the rotation axis, the impulse ring being fixed to the rotating ring, the sensor device being fixed to the non-rotating ring and including a sensor body housing a detection cell. According to the invention, the sensor body also includes an anti-rotating cable output guiding a cable from the detection cell to outside the sensor body and comprising anti-rotating means for preventing rotation of the sensor body and the cable around the rotation axis by cooperation with a support part fixed relative to the rotation axis.

The invention also concerns a mechanical system, for example a motorcycle axle, comprising at least one sensor-bearing unit as mentioned here-above and a support part which is fixed relative to the rotation axis and which includes a groove for receiving the anti-rotating cable output of the sensor body.

Thanks to the invention, sensor device can be locked tangentially to the support part, which is for example a fork belonging to a motorcycle axle. Anti-rotating cable output provides both the functions of guiding cable and of preventing rotation of sensor body and cable around rotation axis, thus efficiently protecting sensor device. Position of anti- rotating cable output is predetermined and stable. Moreover, sensor-bearing unit is compact and adapted to be implemented in narrow environments.

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

- The anti-rotating means are adapted for fitting in a groove formed in the support part.

- The anti-rotating means comprise two plane lateral surfaces for resting contact with two plane borders of a groove formed in the support part.

- The anti-rotating means comprise a plane bottom surface perpendicular to a plane including the rotating axis.

- The anti-rotating cable output extends parallel to the rotation axis opposite the bearing.

- The sensor device also includes a spacer fixed to the sensor body and to the non- rotating ring.

- The spacer and the sensor body comprise conjunct anti-rotating means

- The conjunct anti-rotating means comprise a plane surface formed on the spacer and a plane surface formed on the sensor body, both plane surfaces being perpendicular to a plane including the rotation axis and being positioned in resting contact against each other.

- The spacer has a first face for resting contact against the support part and a second face for resting contact against the non-rotating ring of the bearing.

- The spacer has a first cylindrical surface for fitting inside the sensor body and a second cylindrical surface for fitting inside the non-rotating ring of the bearing. - The impulse ring comprises a target assembly fixed to the rotating ring and a seal assembly fixed to the target assembly and located in a chamber delimited radially to the rotation axis between the rotating ring and the non-rotating ring.

- The impulse ring extends radially to the rotation axis at most up to the rotating ring. According to further aspects of the mechanical system which are advantageous but not compulsory:

- The groove comprises two plane borders receiving two plane lateral surfaces of the anti-rotating cable output in resting contact.

- The groove comprises a plane bottom surface which is perpendicular to a plane including the rotating axis and which faces a plane bottom surface of the anti-rotating cable output, these plane bottom surfaces being separated by a gap radial to the rotation axis when the anti-rotating cable output is received into the groove and adapted to come at least partly in resting contact when the anti-rotating cable output is subjected to a torsional torque.

- The anti-rotating cable output is force-fitted into the groove.

The invention also concerns a method for mounting a sensor-bearing unit in a mechanical system as mentioned here-above, wherein the method comprises at least the following steps:

a) forming the sensor-bearing unit by fastening, on the one hand, the impulse ring to the rotating ring of the bearing and, on the other hand, the sensor device to the fixed ring of the bearing;

b) fastening the sensor-bearing unit to the mechanical system, with the anti-rotating cable output of the sensor body fitted into the groove of the support part.

Step a) is realized before step b).

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be explained in correspondence with the annexed figures, and as an illustrative example, without restricting the object of the invention. In the annexed figures:

- figure 1 is a partial perspective view of a mechanical system according to the invention, of the motorcycle axle type, comprising a support part, a hub and a sensor-bearing unit also according to the invention;

- figure 2 is a side view of the axle along arrow II of figure 1 ;

- figure 3 is a partial exploded perspective view of the axle of figure 1 ;

- figure 4 is another partial exploded perspective view of the axle of figure 1 , showing the support part and a sensor device belonging to the sensor-bearing unit; - figure 5 is a view similar to figure 4, showing the sensor device in an assembled configuration;

- figure 6 is a sectional view along line VI-VI of figure 2;

- figure 7 is a sectional view at a larger scale of detail VII from figure 6; and

- figure 8 is a sectional view at a larger scale along line VIII-VIII of figure 7.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Figures 1 to 8 show a motorcycle axle 1 according to the invention.

Axle 1 equips a vehicle V according to the invention, of the motorcycle type, partially shown on figures 1 and 2. Axle 1 is equipped with a sensor-bearing unit 10 according to the invention.

Axle 1 comprises a fork 2 having a vertical part 3 and a horizontal part 4 delimiting an inner housing 5. Axle 1 also comprises a shaft 6, shown only on figure 2 for simplification purpose, extending along a central axis X1 of axle 1 . Shaft 6 is fitted in housing 5 of fork 2 and in an inner housing 15 of unit 10. Shaft 6 is fixed to part 4 of fork 2 and to a fixed part of unit 10 by fixation means not shown. Axle 1 also comprises a hub 7, shown on figures 2, 3 and 6, mounted on a movable part of unit 10. Hub 7 is adapted to receive a wheel not shown. Hub 7 comprises inner housings 8 and 9 for receiving unit 10. Shaft 6 is not movable in rotation around axis X1 , while hub 7 is movable in rotation around axis X1 .

Instead of axle 1 , unit 10 may equip any suitable mechanical system, preferably belonging to a vehicle V such as a motorcycle, an automotive or a truck.

Sensor-bearing unit 10 comprises a bearing 20, an impulse ring 30 and a sensor device 60. Impulse ring 30 comprises a target assembly 31 and a seal assembly 32. Sensor device 60 comprises a detection cell 62, a cable 64, a sensor body 70 and a spacer 80.

Bearing 20 comprises two rows of rollers 21 , two inner rings 22 and 22' and an outer ring 24. Inner rings 22 and 22' are mounted on shaft 6 and fixed relative to fork 2, shaft 6 and around axis X1 . Outer ring 24 of bearing 20 is fitted inside housing 8 of the hub 7 and movable in rotation around axis X1 . Impulse ring 30 is fixed to outer ring 24, while sensor 60 is fixed to inner ring 22 located on the same side of bearing 20 receiving impulse ring 30. This inner ring 22 has an external cylindrical surface 23 for receiving seal assembly 50 in dynamic sealing contact. Inner rings 22 and 22' each have an internal cylindrical surface delimiting housing 15 for receiving shaft 6. Outer ring 24 has an internal cylindrical surface 25 for fixation of the impulse ring 30 and an external cylindrical surface 26 for fitting inside housing 8. Surfaces 23 and 25 are axial surfaces centered on rotation axis X1 , facing each other and delimiting a chamber 28 radially to axis X1 inside bearing 20. Chamber 28 receives at least partly impulse ring 30 fixed to surface 25. Opposite chamber 28 and impulse ring 30, bearing 20 comprises a seal assembly 29 which is fixed to outer ring 24 and has sealing lips positioned in dynamic sealing contact with inner ring 22'.

Thanks to the design of impulse ring 30, unit 10 has an important compactness. When impulse ring 30 is mounted on bearing 20, the seal assembly 32 and at least partly the target assembly 31 are received in chamber 28. Impulse ring 30 extends radially to rotation axis X1 not beyond rotating ring 24. Impulse ring 30 comprises only two assemblies 31 and 32 and only four parts 33, 34, 35 and 36, allowing easy manufacturing and assembly.

Target assembly 31 comprises a magnetic target 33 and a target holder 34. Target 33 extends substantially radially to axis X1 . Target 33 comprises a face oriented toward sensor device 60 and a face fixed to holder 34. Holder 34 comprises a tubular axial portion for fixation to surface 25 of outer ring 24 and for fixation of seal assembly 32. Holder 34 also comprises an annular radial portion having a face receiving target 33 and a face oriented toward seal assembly 32. Holder 34 is preferably made of metal or plastic. Target 33 and holder 34 may be connected by bonding, vulcanization or by any suitable means.

Seal assembly 32 comprises a radial seal 35 and a seal holder 36. Seal 35 comprises a base fixed to seal holder 36 and a sealing lip which is substantially radial and adapted to be positioned in dynamic sealing contact with surface 23 of inner ring 22. In other words, seal 35 is a radial seal. Seal 35 is advantageously made of elastically deformable material, for example elastomer or thermoplastic. Holder 36 comprises a tubular axial portion for fixation to holder 34. Holder 36 also comprises an annular radial portion having a face oriented toward target assembly 31 and a face oriented toward rollers 21 . Holder 36 is preferably made of metal or plastic. Seal 35 and holder 36 may be connected by molding of seal 35 on holder 36, by bonding, vulcanization or by any suitable means.

Alternatively, seal assembly 32 may comprise only seal 35 but not seal holder 36.

Seal 35 is fixed to target holder 34. Impulse ring 30 comprises only three parts.

According to a possible embodiment, impulse ring 30 may be integrated to bearing

20 previously comprising a seal assembly which is similar to seal assembly 29 and which is fitted in chamber 28 without target assembly. This seal assembly may be removed from surface 25, which receives impulse ring 30. Alternatively, this seal assembly may be removed from surface 25 and mounted on a target assembly, while surface 25 or surface 26 may be machined to receive holder 34 of impulse ring 30. Advantageously, when impulse ring 30 is integrated to an existing bearing 20 without target assembly, sealing surface 23 of the fixed ring 22 is not modified, for example by machining.

Part 4 of fork 2 supports sensor device 60. Part 4 comprises two lateral faces 41 and 42, oriented respectively opposite and toward unit 10. Inner housing 5 extends inside part 4 along axis X1 through faces 41 and 42. Part 4 comprises a substantially cylindrical outer surface 43 rejoining part 3 of fork 2. Part 4 includes a groove 44 formed at surface 43. Groove 44 opens at surface 43 along a top direction located in a plane P1 including axis X1 . Plane P1 corresponds to sectional plane of figures 6 and 7. Groove 44 opens at face 42 toward unit 10. Groove 44 comprises a bottom plane surface 45, two plane borders 46 and a curved surface 47. Surface 45 is perpendicular to plane P1 , while borders 46 are parallel to plane P1 . Surface 47 connects surface 45 to surface 43 by going up from surface 45 between borders 46. Groove 44 receives sensor body 70, as detailed here- below.

Sensor device 60 is partly located inside housing 8 of hub 7, without contact of body

70 or spacer 80 with hub 7. Cell 62 is housed inside body 70 and is schematically represented on figures 6 to 8. Cell 62 detects magnetic field variations induced by magnetic target 33. Cell 62 is positioned as close as possible with respect to magnetic target 33. The accuracy of rotation speed, rotation angle and other data measured by the sensor-bearing unit 10 are highly related to the accuracy of the mounting of the detection cell 62 and the magnetic target 33.

Body 70 is made of plastic or in metal. Body 70 comprises an annular portion 72 centered around axis X1 and a cable output 74 extending from annular potion 72 parallel to axis X1 opposite bearing 20. Cable 64 extends from cell 62 to the outside of body 70 through cable output 74.

Annular portion 72 comprises a face 721 oriented toward impulse ring 30 and a face 722 oriented toward face 42 of part 4. Cell 62 is located as close as possible to face 721 . Annular portion 72 comprises an outer cylindrical surface 723 oriented toward housing 9 of hub 7. Thanks to the particular arrangement of annular portion 72 within axle 1 , without contact between face 721 and impulse ring 30, without contact between face 722 and part 4 and without contact between surface 723 and housing 9, cell 62 is well protected inside body 70. Annular portion 72 also comprises an inner cylindrical surface 724 cut by a plane inner surface 725. Surface 724 is centered on axis X1 , while surface 725 is perpendicular to plane P1 . Surfaces 721 , 724 and 725 receive spacer 80, as detailed here-below.

Cable output 74 guides cable 64 from cell 62 to the outside of body 70. At its extremity 78 opposed to portion 72, cable output 74 comprises means 79 for fastening cable 64, by instance glue, solder, or by an additional elastomeric member. Cable output 74 comprises a plane bottom surface 75 perpendicular to plane P1 and two plane lateral surfaces 76 parallel to plane P1 . When cable output 74 is fitted into groove 44 of fork 2, lateral surfaces 76 come in resting contact with borders 46 of groove 44, while bottom surface 75 faces bottom surface 45 of groove 44, these bottom surfaces 45 and 75 being separated by a gap G radial rotation axis X1 , as shown on figures 7 and 8. Since body 70 is elastically deformable, surfaces 45 and 75 come at least partly in resting contact when cable output 74 is subjected to a torsional torque which is above a particular torque value.

In practice, surfaces 75 and 76 of cable output 74 form anti-rotating means of body 70 around axis X1 relative to support fork 2. In other words, the anti-rotating means 75 and 76 are adapted for preventing rotation of body 70 and cable 64 around axis X1 when cooperating with support fork 2. Preferably, cable output 74 may be force-fitted into groove 44.

Thus, anti-rotating cable output 74 provides both the functions of guiding cable 64 and of preventing rotation of body 70 and cable 64 around axis X1 , consequently protecting sensor device 60.

Spacer 80 is made of plastic or metal. Spacer 80 is fixed to annular portion 72 of body 70 and to inner ring 22 of bearing 20. Spacer 80 comprises three cylindrical portions 82, 84 and 86, among which portions 82 and 84 are cut by a plane surface 85. In other words, portions 82 and 84 are truncated cylindrical portions. An inner cylindrical housing 88 is formed through spacer 80 for receiving shaft 6. Portion 82 has a face 821 oriented toward face 42 of part 4 and a cylindrical surface 822 cut by surface 85. When portion 82 is fitted inside body, surface 822 is resting against surface 724, while surface 85 is resting against surface 725. Portion 84 has a face 841 resting against face 721 of body 70, without contact with cell 62. Portion 84 has a face 842 resting against inner ring 22 of bearing 20. Portion 86 has an outer cylindrical surface 862 for fitting in inner cylindrical housing 15 of inner ring 22.

In practice, spacer 80 is compressed along axis X1 between part 4 of fork 2 and inner ring 22 of bearing 20. Then face 821 is compressed against face 42 of part 4 and face 842 is compressed against inner ring 22. Thanks to its particular form and arrangement, spacer 80 protects sensor housing 70 and specifically cell 62. Moreover, the presence of surface 85 allows freeing space within sensor device 60 to integrate cell 62 as close as possible to impulse ring 30. Furthermore, surface 85 of spacer 80 and surface 725 of body 70 positioned in resting contact against each other form conjunct anti-rotating means between spacer 80 and body 70. Other non-shown embodiments of vehicle V, mechanical system 1 and/or sensor- bearing unit 10 can be implemented without leaving the scope of the invention. For example, constitutive parts of the impulse ring 30 and/or of the sensor device 60 may be different from figures 1 to 8.

Whatever the embodiment, sensor body 70 includes an anti-rotating cable output 74, on the one hand, guiding cable 64 from the detection cell 62 to the outside of sensor body 70 and, on the other hand, comprising anti-rotating means 75 and 76 for preventing rotation of sensor body 70 and cable 64 around axis X1 when cooperating with a support part 2 which is fixed relative to axis X1 .

In addition, technical features of the different embodiments can be, in whole or part, combined with each other. Thus, mechanical system 1 and/or sensor-bearing unit 10 can be adapted in terms of cost or to any specific requirements of the application.