WO2012023001A1

WO2012023001A1 - Rolling bearing assembly and method for mounting such a rolling bearing assembly

Info

Publication number: WO2012023001A1
Application number: PCT/IB2010/002445
Authority: WO
Inventors: Franck Landrieve
Original assignee: Aktiebolaget Skf
Priority date: 2010-08-19
Filing date: 2010-08-19
Publication date: 2012-02-23

Abstract

This rolling bearing assembly (1 ) comprises a rolling bearing (2) comprising an inner ring and an outer ring, a target (4) rotatable around a rotation axis (X-X') of the rolling bearing (2), a sensor unit (6) including at least one sensing element (62) being arranged to read the target with a gap (g) between the sensing element (62) and the target (4), and a target cover (8) with respect to which the target (4) rotates. The target cover (8) comprises positioning means (82) adapted to maintain the gap (g) between the sensing element (62) and the target (4) substantially constant.

Description

ROLLING BEARING ASSEMBLY AND METHOD FOR MOUNTING

SUCH A ROLLING BEARING ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

The invention relates to a rolling bearing assembly and to a method for mounting such a rolling bearing assembly.

BACKGROUND OF THE INVENTION

Rolling bearings equipped with measuring means for determining rotation speed and angles generally use a rotating target and a sensor unit adapted to detect intensity variations of a magnetic field generated by the target. The sensing element of the sensor unit must be positioned as close as possible with respect to the target and with great accuracy. The accuracy of the rotation speed, the rotation angle and other data measured by the sensor unit are highly related to the accuracy of the mounting of the sensing element and the target.

In known rolling bearing assemblies, the sensing element is fixed to various parts of vehicles or on the rolling bearing assembly itself. This implies that the accuracy of the mounting of the sensing element depends on the accuracy of the mounting of several other parts.

SUMMARY OF THE INVENTION

An object of the present invention is to overcome the aforementioned drawback, by providing a rolling bearing assembly having a structure and an arrangement permitting to mount the sensing element as close as possible relative to the target with higher accuracy than assemblies of the prior art.

To achieve this object, the subject matter of the present invention is a rolling bearing assembly comprising:

a rolling bearing comprising an inner ring and an outer ring,

a target rotatable around a rotation axis of the rolling bearing,

- a sensor unit including at least one sensing element being arranged to read the target with a gap between the sensing element and a target, and

a target cover with respect to which the target rotates.

This rolling bearing assembly is characterized in that the target cover comprises positioning means adapted to maintain the gap between the sensing element and the target substantially constant. Thanks to the invention, the sensing element is positioned with respect to the target with great accuracy, especially thanks to a reference area located very close to the target.

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

The target is fast in rotation with the outer ring, the sensor unit is fixed relative to the inner ring, the target cover is fast to the inner ring with possibility for a portion of the target cover equipped with the positioning means to rotate around the rotation axis of the rolling bearing, with respect to the inner ring.

- The target cover comprises an inner element fast in rotation with the inner ring and an outer element equipped with the positioning means, and whereas the inner and outer elements of the target cover are adapted to rotate relative to each other.

The positioning means comprise a surface against which an end of the sensing element is adapted to lay.

- The sensing element reads the target through a protection diaphragm of the target cover facing the target.

The sensing element reads the target radially to the rotation axis of the rolling bearing.

The sensing element reads the target parallely to the rotation axis of the rolling bearing.

The sensor unit comprises a flexible fastening flange adapted to fast the sensing element to a vehicle.

The flexible fastening flange is U-shaped and is adapted to push the sensing element against a surface of the positioning means.

The invention also concerns a method for mounting the above mentioned rolling bearing assembly on a vehicle. This method is characterized in that it comprises the following steps:

a) mounting the rolling bearing, the target and the target cover, the outer ring being fast to a rotating part of the vehicle,

b) mounting the sensor unit on a fixed portion of the vehicle, and

c) rotating the portion of the target cover equipped with the positioning means with respect to the inner ring in order to mount the sensing element relative to the target with the requested gap.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention and its advantages will be well understood on the basis of the following description, which is given as an exhaustive example, without restricting the scope of the invention, and in relation with annexed drawings among which:

Figure 1 is a perspective view of a rolling bearing assembly according to a first embodiment of the present invention;

Figure 2 is a partially exploded perspective view of the rolling bearing assembly of figure 1 ;

Figure 3 is a partial cross section of the rolling bearing assembly of figure 1 ; Figure 4 is a perspective view of a target cover belonging to the rolling bearing assembly of figures 1 to 3;

Figure 5 is a perspective view at an angle different from figure 1 , of a rolling bearing assembly according to a second embodiment of the invention;

Figure 6 is a partial cross section similar to figure 3, of the rolling bearing assembly of figure 5.

DETAILED DESCRIPTION OF SOME EMBODIMENTS

Figures 1 to 4 depict a rolling bearing assembly 1 comprising a ball bearing 2 which has an inner ring 21 and an outer ring 22. Inner and outer rings 21 and 22 rotate relative to each other around a rotation axis X-X', which is also the rotation axis of assembly 1. A radial axis perpendicular to axis X-X' is referenced Y-Y'. In the following description, the terms "axially" and "radially" refer respectively to axis X-X' and Y-Y'.

The assembly 1 also comprises a target 4, also named encoded washer or impulse ring, fast to the outer ring 22 of ball bearing 2. Target 4 comprises a tubular portion 41 which extends around rotation axis X-X' of ball bearing 2. Target 4 comprises also radially extending teeth 43, which are regularly spaced around the circumference of target 4.

Target 4 is adapted to be read by a sensor unit 6 which comprises a sensing element 62 extending along an axis X62, which is parallel to axis X-X' and aligned with teeth 43 of target 4. Sensing element 62 detects the magnetic field variations induced by teeth 43 of target 4, which is made of a magnetic material.

In service state, sensing element 62 reads target 4 with a gap g between an end surface 621 of sensing element 62 and teeth 43 of target 4. The value of gap g is comprised between 0.05 and 5 mm. This gap g should be as small as possible in order to increase the accuracy of the sensing and of the rotation speeds or angles measured by sensor unit 6. In order to protect sensing element 62 and target 4, rolling bearing assembly 1 also comprises a target cover 8, fast in rotation with inner ring 21 , which extends radially from axis X-X' in the vicinity of target 4. Target cover 8 also extends axially around teeth 43 of target 4.

Target cover 8 comprises, on the side of sensing element 62, a positioning area 82 adapted to receive sensing element 62. Positioning area 82 has a shape corresponding to the shape of sensing element 62, and comprises a bottom surface 84 perpendicular to axis X62 and against which end surface 621 is adapted to lay. Bottom surface 84 allows sensing element 62 to be accurately placed with respect to target 4.

On the opposite side of target cover 8 with respect to sensor unit 6, a radially extending seal 10 prevents particulates and other contaminants from reaching the gap between sensing element 62 and teeth 43 of target 4. Seal 10 extends radially between tubular portion 41 of target 4 and an inner surface 86 of target cover 8.

Positioning area 82 comprises a diaphragm 88 extending on a portion of area 82 and through which sensing element 62 reads target 4. Diaphragm 88 permits to prevent particulates and contaminants from reaching the sensing area without reducing the accuracy of the measurements. According to an alternate embodiment, target cover 8 may comprise no diaphragm 88, but an opening towards target 4.

Sensor unit 6 is adapted to be fast to a part of a vehicle such as a fork of a motorcycle, fixed relative to a rotating part, for instance a hub of a wheel. Sensor unit 6 comprises a flexible fastening flange 64 which is U-shaped, a first end of the U being fast to sensor unit 6 and the other end having a hole 641 for fastening on the vehicle. The U- shape of fastening flange 64 allows small displacements of sensing element 62 with respect to the vehicle and an adjustment of sensing element 62 in positioning area 82. Besides, the U-shape of fastening flange 64 provides an elastic effort E1 , exerted on sensing element 62 along axis X62, which presses end surface 621 against bottom surface 84 of positioning area 82. This insures that the requested gap g between sensing element 62 and target 4 is actually established and remains substantially constant.

On figures 2 and 4, several parts of a motorbike are represented in dashed line in order to show how assembly 1 cooperates with its environment. F denotes a front fork of the motorbike, S denotes a shaft supported by fork F and H denotes a hub of a wheel mounted on shaft S.

When mounting rolling bearing assembly 1 on a vehicle, one first mount ball bearing 2 and target cover 8 on shaft S. Inner ring 21 is fast to the shaft, and outer ring 22 is fast to hub H. In the same process, sensor unit 6 is mounted and fast to the fork. Target 4 is then mounted on an outer surface 222 of outer ring 22, and is positioned so as teeth 43 are covered by target cover 8. Seal 10 is then mounted between tubular portion 41 and inner surface 86.

Once this operation has been done, sensing element 62 may not be exactly facing positioning area 82. In order to engage sensing element 62 in positioning area 82, target cover 8 may be placed in an offset position, along axis X-X' with respect to sensing element 62, in order to allow a rotation of target cover 8 around axis X-X' so as for positioning area 82 to face sensing element 62. To allow this rotation, target cover 8 comprises several parts which are integral in translation along axis X-X' and which radially divide target cover 8. A first inner element 90 is integral in movement with inner ring 21 . Target cover 8 comprises also an intermediate element 92, which is linked with inner element 90 with a deformable element 94, which absorbs vibrations between the eccentric portion of target cover 8 and inner element 90. An outer element 96, which carries positioning area 82, is fast in rotation with intermediate element 92. On figure 3, ball bearing 2 is shown as a one piece part.

Rotation of outer element 96 with respect to inner element 90 is permitted by a sliding ability of intermediate element 92 with respect to deformable element 94. The sliding ability may be realized by choosing surface characteristics of an inner surface 921 of intermediate element 92 and elastic properties of deformable element 94.

According to an alternate embodiment, sliding may also be possible between deformable element 94 and inner element 90, or at another interface area between inner and outer elements 90 and 96.

The person who is mounting rolling bearing assembly 1 has therefore the possibility to rotate outer element 96 until positioning area 82 faces sensing element 62, and then to position target cover 8 and the other elements of assembly 1 in their service state as shown on figures 1 and 3. Rotation of outer element 96 with respect to inner element 90 around axis X-X' is manually realized by the person who assembles rolling bearing assembly 1.

A second embodiment of the invention is represented on figures 5 and 6, on which common elements with figures 1 to 4 bear the same references. According to this second embodiment, the reading of target 4 by sensor unit 6 is executed along radial axis Y-Y'. In this configuration, the gap g between sensing element 62 and target 4 is measured along axis Y-Y', teeth 43 of target 4 extending parallely to axis X-X' and sensing element 62 having a reading surface 623 perpendicular to axis Y-Y'. In that case, protection diaphragm 88 is also perpendicular to axis Y-Y'.

In this configuration, no U-shaped fastening flange is used, and sensor unit 6 is fast to fork F by a simple flange 66. However, mounting and positioning process of sensing element 62 with respect to positioning area 82 is done in the same manner as in the first embodiment.

According to an alternate embodiment which is not shown on the figures, target cover 8 may comprise only two elements, a first inner element being fast to inner ring 21 of ball bearing 2, and a second outer element carrying positioning area 82. These two elements may be mounted with possibility to rotate with respect to each other around axis X-X'. Rotation may be allowed by lubrication, special rugosity values or special surface treatments.

Inner element 90 can be made with folded steel sheet, and outer element 96 can be made of punched steel sheet.

Claims

1. - Rolling bearing assembly (1 ) comprising:

a rolling bearing (2) comprising an inner ring (21 ) and an outer ring (22), - a target (4) rotatable around a rotation axis (Χ-Χ') of the rolling bearing (2), a sensor unit (6) including at least one sensing element (62) being arranged to read the target (4) with a gap (g) between the sensing element (62) and the target (4),

a target cover (8) with respect to which the target (4) rotates, wherein the target cover (8) comprises positioning means (82) adapted to maintain the gap (g) between the sensing element (62) and the target (4) substantially constant.

2. - Rolling bearing assembly according to claim 1 , wherein:

- the target (4) is fast in rotation with the outer ring (22),

the sensor unit (6) is fixed relative to the inner ring (21 ),

the target cover (8) is fast to the inner ring (21 ) with possibility for a portion (92, 94, 96) of the target cover (8) equipped with the positioning means (82) to rotate around the rotation axis (Χ-Χ') of the rolling bearing (2), with respect to the inner ring (21 ).

3. - Rolling bearing assembly according to claim 2, wherein the target cover (8) comprises an inner element (90) fast in rotation with the inner ring (21 ) and an outer element (96) equipped with the positioning means (82), and wherein the inner (90) and outer (96) elements of the target cover (8) are adapted to rotate relative to each other.

4. - Rolling bearing assembly according to one of the previous claims, wherein the positioning means (82) comprise a surface (84) against which an end (621 ) of the sensing element (62) is adapted to lay.

5.- Rolling bearing assembly according to one of the previous claims, wherein the sensing element (62) reads the target (4) through a protection diaphragm (88) of the target cover (8) facing the target (4).

6.- Rolling bearing assembly according to one of the previous claims, wherein the sensing element (62) reads the target (4) radially to the rotation axis (Χ-Χ') of the rolling bearing (2).

7. - Rolling bearing assembly according to one of claims 1 to 5, wherein the sensing element (62) reads the target (4) parallely to the rotation axis (Χ-Χ') of the rolling bearing (2).

8. - Rolling bearing assembly according to claim 7, wherein the sensor unit (6) comprises a flexible fastening flange (64) adapted to fast the sensing element (62) to a vehicle.

9.- Rolling assembly according to claim 8, wherein the flexible fastening flange

(64) is U-shaped and is adapted to push the sensing element (62) against a surface (84) of the positioning means (82).

10.- Method for mounting a rolling bearing assembly (1 ) according to claim 2 on a vehicle, wherein it comprises the following steps:

a) mounting the rolling bearing (2), the target (4) and the target cover (8), the outer ring (22) being fast to a rotating part (H) of the vehicle,

b) mounting the sensor unit (6) on a fixed portion (F) of the vehicle, and c) rotating the portion (92, 94, 96) of the target cover (8) equipped with the positioning means (82) with respect to the inner ring (21 ) in order to mount the sensing element (62) relative to the target (4) with the requested gap (g).