TECHNICAL FIELD OF THE INVENTION

The invention relates to a support member for holding at least one sensor with respect to an encoder washer, such a sensor being used to detect a rotation parameter of encoder washer. This invention is particularly useful for detecting the rotation of a rotatable ring of a bearing with respect to a fixed ring.

This invention also relates to a rotation detection set which comprises, amongst others, an encoder washer, at least one sensor and a support member as mentioned here-above. The invention also concerns a bearing assembly comprising a bearing, with a fixed ring and a rotatable ring, and a rotation detection set as mentioned here-above.

BACKGROUND OF THE INVENTION

Generally speaking, a bearing comprises an inner ring and an outer ring adapted to rotate around a rotation axis, one with respect to the other. In a plain bearing, the two rings are in sliding contact. In a rolling bearing, several rolling bodies are installed between the two rings. These rolling bodies can be balls, rollers or needles. Thus, a rolling bearing can be, for instance, a ball bearing, a roller bearing or needle bearing.

In the field of bearings, it is known to use a tachometer in order to determine the rotation speed of a member supported by a bearing. As explained in EP-A-1 933 157, one can use an encoder washer with magnetic poles fast in rotation with a rotatable ring of a bearing, and one or several sensors distributed around the encoder washer or located in front of it. The or each sensor must be connected to an electronic control unit to which it provides a signal representative of a rotation parameter of the encoder washer. The or each sensor is thus connected, either directly or via a printed circuit board, to a cable which can be a shielded cable in order to reduce EMI (electromagnetic interference) noise, in the electrical signal(s) emitted by the sensor(s). The shielding of the cable is more efficient when it is connected to a grounded part. In the known devices, connection of the shielding of a cable to a grounded part is cumbersome and needs a highly qualified manpower.

SUMMARY OF THE INVENTION

The invention aims at solving these problems with a new support member which facilitates the connection of a grounded part to a part of cable. To this end, the invention concerns a support member for holding at least one sensor with respect to an encoder washer, this support member defining a housing adapted to accommodate an end of a cable connected, directly or via a printed circuit board, to the sensor, wherein the support member has a hollow protrusion whose internal volume connects the housing to a zone defined by the support member and adapted to accommodate an electrically conductive member.

Thanks to the invention, connection of a cable shielding to a grounded part can occur thanks to a wire going through the internal volume of the hollow protrusion in order to be in contact with an electrically conductive member received in the zone defined by the support member. This electrically conductive member can be easily grounded, e.g. when it is mounted on a ring of a rolling bearing.

In the present description, unless otherwise specified, the words "axial", "radial", "axially" and "radially" relate to an axis which can be the axis of rotation of the encoder washer or a central axis defined by the support member. A direction is "axial" when it is parallel to such an axis and a direction or an axis is "radial" when it is perpendicular to and secant with such an axis.

According to further aspects of the invention which are advantageous but not compulsory, the support member might incorporate one or several of the following features, taken in any technically admissible configuration:

- The support member comprises a first wall, a second wall and a third wall connecting the first and second walls, whereas the housing and the zone of the support member are located on either sides of the third wall and the hollow protrusion extends along one of the first and second walls. In such a case, the wall along which the hollow protrusion extends forms the outer radial part of the hollow protrusion, and the internal volume of this hollow protrusion communicates with the first housing through an opening.

- The internal volume of the hollow protrusion is adapted to accommodate an electrical connector.

The invention also concerns a rotation detection set comprising an encoder washer, adapted to rotate around a rotation axis, at least one sensor, adapted to detect a rotation parameter of the encoder washer around the rotation axis, an electric cable, adapted to connect the sensor to an electric device, a support member as mentioned here-above and an electrically conductive member. In such a rotation detection set, an end of the cable is received within the housing of the support member, the electrically conductive member is accommodated in the zone of the support member and a wire of the cable extends within the internal volume of the hollow protrusion and is electrically connected to the electrically conductive member. Such a detection set reduces the EMI noise on the signal(s) conveyed by the electric cable because the wire can be used to ground a shielding of the cable.

Advantageously, an electric connector is mounted at the end of the wire and housed in the internal volume of the hollow protrusion in a position such that it is in electrical contact with the electrically conductive member. This electrical connector can have an elastic portion adapted to exert a resilient biasing effort onto the electrically conductive member.

Alternatively, the end of the wire can be directly engaged in a slot of the electrically conductive member. Such a slot can be a locking and/or a stripping slot for said wire.

If the cable is a shielded cable, the wire can belong or be connected to a shielding of this cable.

The electrically conductive member is advantageously an annular flange, which facilitates mounting of the rotation detection set on a circular part, such as a fixed ring of a bearing.

Finally, the invention concerns a bearing assembly comprising a bearing, with a fixed ring and a rotatable ring, and a rotation detection set as mentioned here-above, the encoder washer of this rotation detection set being fast in rotation with the rotatable ring, whereas the support member is mounted onto the fixed ring via the electrically conductive member.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be better understood on the basis of the following description which is given 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 perspective view of a rolling bearing assembly according to the invention,

figure 2 is a partial cut view along line ll-ll on figure 1 , a cover being omitted figure 3 is an exploded perspective view of the rolling bearing assembly of figure 1 ,

- figure 4 is an exploded perspective view of a rotation detection device of a rotation detection set belonging to the rolling bearing assembly of figures 1 to 3, figure 5 is a perspective view of a support member and a cable belonging to the rotation detection device of figure 4, from an angle different from figure 4, figure 6 is a perspective view of the support member represented on figure 5, from another angle, figure 7 is a cut and perspective view of the support member of figures 5 and 6, taken along line VII-VII on figure 5, and

figure 8 is an enlarged perspective view of a connector belonging to the cable represented on figure 5.

DESCRIPTION OF SOME EMBODI MENTS

The rolling bearing assembly A represented on the figures comprises a rolling bearing 2 having a fixed outer ring 4 and an inner ring 6 rotating around a central axis X2 of rolling bearing 2. Several balls 8 forming rolling bodies are received within a chamber 10 defined between rings 4 and 6. These balls are held in position with respect to these rings by a cage 12.

An encoder washer 20 is fast in rotation with inner ring 6 and comprises a metallic armature 22 and a magnetic body 24 which defines several magnetic North poles N and South poles S. Encoder washer 20 is centered on an axis X20 superimposed with axis X2 when encoder washer 20 is mounted onto inner ring 6 by snapping of armature 22 within an inner peripheral groove 6A of ring 6.

A sensing device 40 is mounted onto ring 4 in order to detect a rotation parameter of encoder washer 20, thanks to the variable magnetic field generated by this washer upon rotation. A rotation parameter can be a position, a speed, an acceleration or any other parameter representative of the rotation of encoder washer 20 around axes X2 and X20.

Sensing device 40 includes an annular electrically conductive flange 42 having a peripheral skirt 422 adapted to be snapped within an outer groove 4A of outer ring 4 which is electrically conductive. Thus, when rolling bearing 2 is grounded, by contact of ring 4 with a grounded part, flange 42 mounted onto ring 4 is also grounded. Items 42 and 4 are advantageously metallic.

Flange 42 is centered on an axis X42 which is superimposed with axis X2 when sensing device 40 is mounted on rolling bearing 2. Flange 42 is provided with a flat wall 424, perpendicular to axis X42 and provided with an oblong opening or through hole 426, of an arcuate shape centered on axis X42. Three circular holes 428 are also provided on wall 424 in order to guarantee a robust mechanical anchorage of support member 44 onto flange 42. Indeed, when support member 44 is overmolded onto flange 42, some plastic material will flow through holes 428 and remain there after solidification.

Sensing device 40 also includes a support member 44 of an arcuate shape, having an inner wall 441 in the form of a section of a circular cylinder centered on an axis X44 which is superimposed with axes X2 and X42 when support member 44 is mounted onto flange 42 and sensing device 40 is mounted onto ring 4. Support member 44 also has an outer wall 442, which is parallel to inner wall 441 , and a flat wall 443 which is perpendicular to axis X44 and lies against flat wall 424 when support member 44 is mounted onto flange 42. Flat wall 443 connects inner wall 441 to outer wall 442.

The geometry of support member 44 is defined in connection to axis X44. For the parts of support member 44, the words "axial" or "radial" are defined with respect to this axis.

Support member 44 has an extension 445 which protrudes from the face of wall 443 which lies against wall 424 in the mounted configuration of support member 44 onto flange 42. The global shape of extension 445 is such that it can be inserted within opening 426. Extension 445 is arcuate and centered on axis X44. The inside volume V ₄₄₅ of extension 445 defines five slots S ₄₄₅ separated by four ribs 446. A holder 46 holds five sensors in a position such that they can be inserted together within volume V ₄₄₅ , with one sensor in each slot S ₄₄₅ . Figure 4 shows four sensors, with references 48A, 48B, 48C and 48D, the fifth sensor being omitted to show holder 46. Holder 46 also holds a printed circuit board or PCB 49 and the sensors are connected to this PCB via their respective pins.

When all sensors are received within volume V ₄₄₅ , PCB 49 is received within a volume V ₄₄₃ defined by support member 44 above wall 443, that is between walls 441 and

442, on the side of wall 443 opposite to extension 445. Thus, volume V ₄₄₃ forms a housing for PCB 49.

Support member 44 defines a zone Z ₄₄ where flange 42 is partly accommodated when support member 44 is mounted onto flange 42. Zone Z ₄₄ is defined between extension 445 and a part 441A of wall 441 which extends from wall 443, in the same direction as extension 445. Considering the position of support member on figures 4 and 5, part 441A can be considered as the lower part of wall 441 which extends below wall

443, as extension 445.

Support member 44 is also provided with a hollow protrusion 448 which protrudes outwardly with respect to wall 442, in a direction radial with respect to axis X44. V ₄₄₈ denotes the internal volume of protrusion 448. 442A denotes the upper edge of wall 442 that is the edge of wall 442 which is opposite to wall 443. Protrusion 448 has a part 448A which extends from wall 443, opposite to edge 442A. Zone Z ₄₄ is defined also between wall part 441 A and protrusion part 448A.

Part 448A is provided with two ribs 448B separated by a groove 448C parallel to axis X44. Ribs 448B extends outwardly from part 448A, that is in a direction away from wall 441 and from zone Z ₄₄ . On its side oriented towards wall 441 , part 448A is provided with an opening 448D which connects volume V ₄₄₈ to zone Z ₄₄ .

On the other hand, wall 442 defines the outer radial part of hollow protrusion 448 between wall 443 and edge 442A. An opening 448E extends between wall 443 and edge 442 and connects volumes V ₄₄₃ and V ₄₄₈ .

As shown on figure 5, one can consider that hollow protrusion 448 extends along wall 442, insofar as it protrudes radially outwardly with respect to axis X44 from this wall.

A multiconductor cable 45 is used to connect PCB 49 to a non represented electronic control unit adapted to receive the output signals of sensors 48A to 48D. The ends of some conductors 452 of cable 45 are connected to respective terminals 492 of PCB 49. Cable 45 is a shielded cable which includes an electrically conductive shield 454 embedded within a sheath 456 of cable 45. Shield 454 is connected to a conductor 458 whose end is connected to an electrical connector or plug 460 obtained by cutting and folding a metallic strip. Plug 460 has an elastically deformable tongue 462. The geometry of plug 460 is such that it can be inserted within volume V ₄₄₈ , while being connected to conductor 458 and with tongue 462 protruding within zone Z ₄₄ through opening 448D.

Thus, when support member 44 is mounted onto flange 442, conductor 458 and plug 460 elastically connect shield 454 to flange 442. When flange 442 is grounded, thanks to its mounting onto fixed ring 4, shield 454 is thus grounded, which enables it to reduce EMI noise in the signals conveyed by cable 45.

During manufacturing of sensing device 40, plug 460 is mounted at the end of conductor 458 and conductors 452 are respectively connected to terminals 492 before or after the respective pins of sensors 48A to 48E and the non represented sensor are connected to PCB 49. It is then possible to install holder 46 equipped with sensors 48A to 48E and PCB 49 within volume V ₄₄₅ , with PCB 49 lying in volume V ₄₄₃ together with an end 45A of cable 45. Cable 45 goes through a slot 450 of support member 4. When installing the end 45A of cable 45 within volume V ₄₄₃ , plug 460 is inserted within volume V ₄₄₈ of hollow protrusion 448 so that its tongue 462 protrudes within zone ¾ ₄ .

It is then possible to close volume V ₄₄₅ with a cover 43.

Then, support member 44 is mounted onto flange 42 and shield 454 is automatically set to the same electrical potential as flange 42.

When support member 44 is mounted onto flange 42, elastic tongue 462 exerts on the radial outer surface 425 of flange 42 an elastic biasing effort because elastic tongue 462 is slightly deformed towards volume V ₄₄₈ when flange 42 is introduced within zone Z ₄₄ . This biasing effort induces an efficient electric contact between plug 460 and flange 42. A rotation detection set according to the invention includes encoder washer 20 and sensing device 40.

According to a non represented embodiment of the invention, plug 460 can be omitted and the end of cable 458 can extend within volume V ₄₄₈ and go through opening 448D in order to be engaged within a slot of flange 42 where it can be locked. Alternatively or in complement, the slot can be a stripping slot for stripping the sheath of conductor 458.

According to a non represented embodiment of the invention, support member 44 can be overmoulded over flange 42.

Even if it is particularly advantageous, holder 46 is optional. It is possible to install individually the sensors 48A to 48E within the housing V ₄₄₅ .

The invention has been represented with five sensors. However, it can be implemented with one or several sensors, whose number can be different from five.

The invention is represented with the sensors 48A to 48D connected to cable 45 via PCB 49. Alternatively, in particular when only one sensor is used, the sensor of sensors can be connected directly to the cable.

The invention has been represented with a rolling bearing. However, it is also usable with a plain bearing.

The invention has been represented with a fixed outer ring and a rotating inner ring. However, it is also usable with a fixed inner ring and a rotating outer ring.