ROLLING BEARING ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates to a rolling bearing assembly comprising, amongst others, a target and a sensor unit with at least one sensing element adapted to read the target. The invention also relates to a tool and a process for mounting such a rolling bearing assembly onto a support member. TECHNICAL FIELD OF THE INVENTION

A rolling bearing comprises an inner ring, an outer ring and several rolling bodies installed between these two rings. These rolling bodies can be balls, rollers or needles. In the sense of the present invention, a rolling bearing can be, for instance, a ball bearing, a roller bearing or a needle bearing.

It is known to use a tachometer in order to determine the rotation speed of a member supported by a rolling bearing. As considered in EP-A-1 251 354, one can use a sensor assembly including an active part, such as a magnetic multipolar ring, forming a target whose rotation is detected by a sensing element mounted in a sensor unit body fast in rotation with the inner ring of a ball bearing. The target is mounted on a synthetic support member. When they are aligned along the rotation axis of the rolling bearing, the sensor unit body and the synthetic support member hide the rolling bearing, so that this bearing is not accessible. Therefore, in case one needs to mount the rolling bearing assembly onto a support member, one must push the rolling bearing by an action on an exposed lateral face of the sensor unit body or the synthetic support member, which might damage or destroy this element.

SUMMARY OF THE INVENTION

This invention aims at solving the above-mentioned problem with a new rolling bearing which can be easily and safely mounted onto a support member.

To this end, the invention concerns a rolling bearing assembly comprising a rolling bearing, having an inner ring and an outer ring, a target adapted to rotate with the inner ring or with the outer ring, around a rotation axis of the bearing, and a sensor unit comprising a sensor unit body supporting at least one sensing element adapted to read the target. According to the invention, the sensor unit body is provided with at least one recess giving access to a lateral face of at least one of the inner ring and outer ring when the sensor unit is in a working position with respect to the rolling bearing. Thanks to the invention, the recess of the sensor unit body can be used to introduce a part of a tool in order to exert a thrust effort onto the lateral face of the inner ring or outer ring of the rolling bearing. This allows to push this rolling bearing into a housing of a support member.

In the present description, the words "axial", "radial", "axially", "radially", "centrifugal",

"centripetal" and similar words relate to the axis of rotation of one ring of the rolling bearing with respect to the other ring. A direction is "axial" when it is parallel to this axis and "radial" when it is perpendicular and secant to this axis. A surface is "axial" when it is perpendicular to this axis and "radial" when a direction perpendicular to this surface is radial. For instance, an axial effort is parallel to the axis of rotation and an axial surface is annular and perpendicular to this axis.

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

- The target rotates with the outer ring of the rolling bearing and the sensing element is mounted in a supporting part of the sensor unit body which defines, with an inner radial face of the target, a radial gap through which the sensing element reads the target and the recess is formed by a part of the sensor body having a reduced outer diameter, as compared to the outer diameter of the supporting part.

- The target rotates with the inner ring of the rolling bearing and the sensing element is mounted on a supporting part of the sensor body which defines, with an outer radial face of the target, a radial gap through which the sensing element reads the target and the recess is formed by a part of the sensor body having an enlarged inner diameter, as compared to the inner diameter of the supporting part.

- The recess is provided in an intermediate part of the sensor unit body, between its inner radial surface and its outer radial surface.

- The sensing unit has several sensing elements, each mounted in a respective supporting part and a recess is provided between each pair of two adjacent supporting parts.

- The recess is a hole going through the sensor unit body, from one lateral face of this body to the opposite lateral face of this body. In such a case, the opening can be equipped with a deformable sealing arrangement, movable between a sealing configuration and an open configuration where it grants access to the opening.

- The recess has an end wall adapted to transmit a thrust effort exerted through the recess onto the inner ring and/or the outer ring of the ball bearing. The invention also concerns a tool to be used with a rolling bearing assembly as mentioned here-above in order to mount it onto a support member. This tool has at least one projection of a cross-section adapted for it to go through one recess of the sensor unit body in order to exert a thrust effort on the lateral face of a corresponding ring of the rolling bearing.

Finally, the invention concerns a process for mounting a rolling bearing assembly as mentioned here-above onto a support member, this method comprising the steps of:

a) fastening the sensor unit body to the rolling bearing,

b) pushing the rolling bearing into a corresponding housing of the support member with a thrust axial effort exerted on a lateral face of the ring of the rolling bearing, through the recess of the sensor unit body.

Advantageously, the process comprises a further step of c) fastening a flange equipped with the target to one of the rings of the rolling bearing. 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 hub and a fork of a two-wheeled vehicle, the hub including a rolling bearing assembly according to the invention,

figure 2 is a partial cross-section, at a larger scale and along plane II on figure 1 , showing a rolling bearing assembly used in the device of figure 1 ,

figure 3 is an enlarged view of detail III on figure 2,

figure 4 is a sectional view along line IV-IV on figure 2,

- figure 5 is a perspective exploded view of the rolling bearing assembly represented on figures 2 to 4, showing how this assembly is mounted with respect to the shaft and the hub shown on figures 1 to 3 which are partially represented in chain-dotted lines,

figure 6 is a sectional view, in a plane similar to the one of figure 4, of a sensor unit body belonging to a rolling bearing assembly according to a second embodiment of the invention,

figures 7, 8 and 9 are respective sectional views similar to figure 6 for a third, a fourth and a fifth embodiment of the invention,

figure 10 is a cut view along line X-X on figure 9 during a process according to the invention, figure 1 1 is a cut view similar to figure 10 for a sixth embodiment of the invention, and

figure 12 is a cut view similar to figure 10 for a rolling bearing assembly according to a seventh embodiment of the invention.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Figure 1 depicts the use of a rolling bearing assembly 2 in conjunction with a shaft 4 and a hub 6. The hub 6 belongs to a non-represented wheel which is held by two fork members 8 supporting shaft 4. The rolling bearing assembly 2 of the invention is used in conjunction with another rolling bearing assembly 3 in order to support, with a possibility of rotation, hub 6 around shaft 4 which is stationary when fork members 8 are stationary.

Rolling bearing assembly 2 includes a ball bearing 10 comprising an inner ring 102 and an outer ring 104 defining between them a rolling chamber where balls 106 are held in position by a cage 108. Ring 102 is fast with shaft 4 and ring 104 is rotatable around a central axis X ₁₀ of rolling bearing 10 which is superimposed with the central longitudinal axis X ₄ of shaft 4 when rolling bearing 10 is mounted on shaft 4.

Rolling bearing assembly 2 also includes means to determine a rotation parameter of the outer ring 1 04 , with respect to the in ner ring 102. A rotation parameter is representative of the pivoting movement of one part with respect to another. Such a parameter can be an angle measuring the angular position of one part with respect to the other, around the central axis X ₁₀ of ball bearing 10. Such a parameter can also be a speed, a displacement, an acceleration or a vibration.

These detection means include a sensor unit 20 having a body 202 supporting a Hall effect cell 204 forming a sensing element. An electric cable 205 connects cell 204 to an appropriate electronic control unit which is remote from rolling bearing assembly 2.

Alternatively, some electronic components can be embedded in body 202 in order to treat the output signal of cell 204.

Body 202 is mounted on an annular shoe 203 which also belongs to sensor unit 20.

Shoe 203 is fitted around shaft 4 and wedged onto inner ring 102 thanks to a skirt 2032 blocked in an inner peripheral groove 1022 of inner ring 102. Thus, body 202 is fast in rotation with inner ring 102. A terminal nut 40 is mounted on shaft 4 and adapted to exert on shoe 203 an axial effort E ₄₀ , that is an effort parallel to axis Xi ₀ . This axial effort is transmitted, as an effort E ₃₀ , by shoe 203 to inner ring 102 which is in abutment against a spacer 42 extending between rolling bearing assemblies 2 and 3.

A metallic flange 50 is wedged on outer ring 104. Flange 50 acts as a cover for an encoder washer 60 which constitutes a target for Hall effect cell 204. Encoder washer 60 is magnetically active and includes several magnetic North and South poles regularly distributed around axis Xi ₀ in working configuration of rolling assembly 2. Encoder washer 60 is mounted on the radial inner face 502 of flange 50. Encoder washer 60 can be glued onto face 502 or blocked against this surface by an elastic deformation of flange 50.

Sensing element 204 is arranged to detect encoder washer 60 in a radial direction.

Flange 50 includes a first cylindrical portion 504 having a circular cross-section and defining face 502. Flange 50 also includes a second cylindrical portion 506 with a circular cross-section, these two portions being joined together by an annular portion 508 which is perpendicular to axis Xi ₀ . Thanks to annular portion 508, portions 504 and 506 can have different inner diameters.

Portion 506 is wedged onto outer ring 104. More precisely, portion 506 is introduced within an outer groove or recess 1042 of outer ring 104, so that items 50 and 104 are fast in rotation with each other. Other possibilities to fasten flange 50 onto outer ring 104 include gluing, force fitting and screwing.

D-104 denotes the outer diameter of outer ring 104, that is the maximum diameter of ball bearing 10. The smaller this diameter, the more compact ball bearing 10 is and the more compact rolling bearing assembly 2 can be. d ₆ o denotes the internal diameter of encoder washer 60, that is the dimension of the target which determines the geometry of a radial air gap G formed between the part of body 202 which surrounds cell 204 and the radial inner face 602 of encoder washer 60. Diameter d ₆ o is actually the diameter of face 602. Diameter d ₆ o is larger than diameter D ₁₀₄ . This allows encoder washer 60 to be large enough to define several well differentiated magnetic poles, even if diameter D ₁₀₄ is small.

A sealing gasket 70 is mounted on body 202 and extends radially outwardly from this body, so that its terminal deformable lip 72 comes in sliding contact against radial inner face 502 of flange 50. Thus, air gap G and encoder washer 60 are efficiently protected against pollution, in particular water or humidity.

As shown on figure 4, sensor unit body 202 has a cylindrical inner radial surface 2022 with a circular cross-section, adapted to surround shoe 203. Hall effect cell 204 is embedded into a radial projection 2024 of sensor unit body 202 which surrounds and protects cell 204. Projection 2024 extends radially outwardly, with respect to axis Xi ₀ within a first angular sector having an included angle a of about 30°. R MAX denotes the radius of the outer radial surface 2025 of projection 2024. The radial thickness of air gap G equals the difference between twice R _M AX and d ₆ o-

Outside the angular sector of projection 2024, sensor unit body 202 has a cylindrical outer radial surface 2026 which has a radius R _MIN smaller than radius R _M AX- Thus, an empty space or recess R is formed around the part 2028 of sensor unit body 202 surrounded by surface 2026. This recess R extends radially between surfaces 2026 and 602, on a second angular sector having an included angle β equal to 360° minus the value of a, that is about 330° in the example of figure 4

When sensor body 202 is mounted on inner ring 102, recess R gives access to the lateral face 1044 of outer ring 104 on the second angular sector having β as to included angle, that is on most of its circumference.

Thanks to this recess R, a tool 1000 can be used to exert a thrust onto surface 1044 after sensor unit body 202 and flange 50 have been mounted, respectively on inner ring 102 and outer ring 104.

Tool 1000 includes a partly cylindrical body 1002 and driving rod 1004 rigidly connected to body 1002. Body 1002 forms, with respect to driving rod 1004, an axial projection having a shape adapted to go through recess R, without interference with radial projection 2024. To this end, body 1002 has a longitudinal slot 1006 adapted to accommodate projection 2024.

Mounting of rolling bearing assembly 2 on hub 6 occurs as follows: sensor unit 20 is mounted onto ring 102 by the introduction of skirt 2032 within groove 1022. Then, flange 50 is mounted onto ring 104 by the introduction of cylindrical portion or skirt 506 within groove 1042. Alternatively, mounting of flange 50 onto ring 104 can occur before mounting of sensor unit 20 onto inner ring 102. Irrespective of the order of these steps, they result in the sensor unit 20 and encoder washer 60 being in a working position with respect to ball bearing 10.

Thanks to the configuration of part 2028 of body 202, the recess R formed around surface 2026 gives access to surface 1044 of ring 104, from the side of unit 20 which is opposite to ball bearing 10, that is from the side of sensor unit body visible on figure 5 and oriented to the left on figures 2 and 3.

It is thus possible to use toll 1000 in order to push ball bearing 10 within a housing 62 of hub 6 by exerting a direct thrust effort E-i onto surface 1044. This effort does not risk to damage sensor unit 20 or encoder washer 60, since it is exerted through recess R.

When rolling bearing 10 is correctly positioned within housing 62, it is then possible to instal l seal ing gasket 70 arou nd sensor u n it body 202 in order to obtain the configuration of figures 1 to 3.

In the second to seventh embodiments of the invention represented on figures 6 to 12, elements similar to the ones of the first embodiment have the same reference numbers. Hereafter, mainly differences between these embodiments and the first one are mentioned. In the second embodiment of the invention represented on figure 6, sensor unit body 202 includes two projections radial 2024-1 , 2024 ₂ where two sensing elements 204-1 and 204 ₂ are located. Two recesses R-i and R ₂ are formed between projections 2024-1 and 2024 ₂ at the level of two portions 2028-, and 2028 ₂ of body 202 whose outer radial surfaces 2026-1 , 2026 ₂ have a diameter R _min smaller than the diameter R _M AX of the outer radial surfaces 2025-, and 2025 ₂ of the projections 2024-, and 2024 ₂ .

A tool adapted to be used with this sensor body includes two projections having a C shape of about 150°, corresponding to the shape of recesses Ri and R ₂ .

In the embodiment of figure 7, sensor unit body 202 holds four sensing elements 204-1 to 204 ₄ embedded each in a radial projection 2024-1 to 2024 ₄ . Four recesses R-i, R ₂ , R ₃ and R ₄ are defined around body 202 by portions of this body having an outer radial surface of a reduced diameter R _min , as compared to the radius R _M AX of the projections 2024 _! to 2024 ₂ .

The embodiment of figure 8 corresponds to the case where two sensing elements 204i and 204 ₂ are supposed to read a target 60 partially represented in chain-dotted lines and located radially inside the sensor unit body 202. This corresponds to the case where sensor unit 20 is fastened to the outer ring of a rolling bearing, which is stationary, whereas the target 60 is fastened to the inner rotating ring of this rolling bearing. In this context, a radial inner projection 2024-1 or 2024 ₂ is created around each unit 204-1 and 204 ₂ . Two parts 2028-1 and 2028 ₂ of body 202 have an inner diameter Γ _Μ ΑΧ which is larger than the inner diameter r _min of the inner radial surface 2025-1 and 2025 ₂ of projections 2024-1 and 2024 ₂ . This difference in diameter creates two recesses R-i and R ₂ within body 202, radially inside parts 2028i and 2028 ₂ . These recesses Ri and R ₂ give access to a lateral face of the inner ring of a bearing when sensor unit body 202 is mounted on such a bearing.

According to non-represented alternative embodiments of the invention, one or more than three sensing elements 204 can be used with a sensor unit body 202 surrounding the target. Then, the number of recesses is adapted.

In the embodiment of figures 9 and 10, four openings O-i, 0 ₂ , 0 ₃ and 0 ₄ are created in four intermediate zones of a sensor unit body 202 which supports a sensing element 204. Each opening constitutes a recess through sensor unit body 202. These openings O-i to 0 ₄ are created about midway between the inner radial surface 2022 and the outer radial surface 2025 of sensor unit body 202. Each opening O-i to 0 ₄ goes through sensor unit 202, from a first lateral face 2027 to the opposite lateral face 2029. Figure 10 shows how sensor body 202 is positioned with respect to the inner and outer rings 102 and 104 of a ball bearing 10 when it is fastened to the inner ring 102 and when a metallic flange 50 holds an encoder washer 60, as in the first embodiment. Opening Oi gives partially access to a lateral face 1044 of outer ring 104 and to a lateral face 1024 of inner ring 102.

A tool with four fingers, one of which is represented on figure 10 with reference 1002 is used to act directly onto surfaces 1044 and 1024 when one uses and axial effort thrust E-i to push ball bearing 1 0 within a recess 62 of a support member, such as hub 6 in the first embodiment.

In the sixth embodiment of the invention represented on figure 1 1 , the opening O-i is equipped with two sealing lips 81 and 82 which isolate opening Oi and ball bearing 10 from the outside. When a fi nger 1 002 of a tol l is used to push ball bearing 1 0 as a consequence of an axial thrust effort E-i , sealing lips 81 and 82 are elastically deformed, in the direction of arrows A, thus giving access to opening O-i for finger 1002.

In the seventh embodiment of figure 12, a recess R-i is made within a sensor unit body 202, this recess being opened to the outside, that is to the left of figure 12, in order to accommodate a finger 1002 of a tool when necessary. This recess R-i is closed by an end wall 2023 formed by sensor unit 202 which permanently isolates ball bearing 10 from the outside. As the axial thickness t of wall 203 is much smaller than the axial thickness T of body 202, wall 203 does not hinder the force transmission between finger 1002 and the lateral faces 1 024 and 1 044 of the rings 1 02 and 1 04 of bal l bearing 1 0 , when it is necessary to push this ball bearing with in a housing such as housi ng 62 of the first embodiment, with an axial thrust effort E-| .

The features of the embodiments mentioned here-above can be combined.

As mentioned here-above, the invention is particu larly adapted for real izin g a tachometer of a two-wheeled vehicle. However, other applications can be considered.