WO2010116206A1

WO2010116206A1 - Rolling bearing assembly with rotation sensing means and device equipped with such an assembly

Info

Publication number: WO2010116206A1
Application number: PCT/IB2009/052783
Authority: WO
Inventors: Sylvain Tucholski
Original assignee: Aktiebolaget Skf
Priority date: 2009-04-07
Filing date: 2009-04-07
Publication date: 2010-10-14
Also published as: EP2417463A1

Abstract

This rolling bearing assembly (10-110) comprises a rolling bearing (20) with an inner ring (22), an outer ring (24) and rolling bodies (26) between the inner and outer rings, a flange (10) with a housing (14) where the rolling bearing is at least partially received, sensing means (50, 60) adapted to detect a rotation parameter of one of the rings (22) with respect to the other (24), and electric connecting means (100-110) adapted to connect the sensing means to voltage supply means and/or to an electronic control unit (220). The electric connecting means include an electric connector (110) sealingly mounted through the flange and an electric cable (100) connecting the electric connector (110) to the sensing means (50, 60).

Description

ROLLING BEARING ASSEMBLY WITH ROTATION SENSING MEANS AND DEVICE EQUIPPED WITH SUCH AN ASSEMBLY

TECHNICAL FIELD OF THE INVENTION

This invention relates to a rolling bearing assembly comprising, amongst others, sensing means adapted to detect a rotation parameter of one ring of a rolling bearing with respect to the other ring of this rolling bearing, the rings being rotatable one with respect to the other. The invention also relates to a device, in particular an electric machine such as an electric motor, with a rotating shaft, this device being equipped with such a rolling bearing assembly.

BACKGROUND 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 meaning of the present invention, a rolling bearing can be, for instance, a ball bearing, a roller bearing or a needle bearing.

In the field of rolling bearings, it is known to use a tachometer in order to determine the rotation speed of a member supported by a rolling bearing. In such a case, a sensor is generally mounted on a support member, in the immediate vicinity of an encoder washer fast in rotation with one of the rings of the rolling bearing, for instance its inner ring. Such a sensor can be associated with a printed circuit board which supports electrical components adapted to supply the sensor with an adapted voltage and to generate an electronic signal to be processed by an electronic control unit (ECU). Therefore, an electric line must be established between the printed circuit board and a voltage source and/or an ECU, this line extending partly outside an electric machine equipped with such an instrumented ball bearing assembly. The part of the electric line which is accessible from outside the motor can be damaged or even cut, which makes the sensor useless and necessitates some complicated and time consuming maintenance operations. SUMMARY OF THE INVENTION

This invention aims at solving this problem with a new rolling bearing assembly which improves the serviceability of a device equipped with such an assembly.

To this end, the invention concerns a rolling bearing assembly comprising:

- a rolling bearing with an inner ring, an outer ring and rolling bodies between the inner and outer rings,

- a flange with a housing where the rolling bearing is at least partially received,

- sensing means adapted to detect a rotation parameter of one of the rings with respect to the other, and

- electric connecting means adapted to connect the sensing means to voltage supply means and/or to an electronic control unit, wherein the electric connecting means include an electric connector sealingly mounted through the flange and an electric cable connecting the electric connector to the sensing means.

Thanks to the invention, the electric cable which connects the sensing means to the electric connector is protected from the outside environment since it does not have to extend through the flange because the connector forms an interface with an outer electric line which can be installed between this connector and the voltage supply means and/or the electronic control unit. In other words, the flange can constitute a protecting device for the cable and the sensing means which are not subject to improper forces, such as a pulling effort which could be exerted if the cable were to extend through the flange.

In the present description, the words "axial", "radial", "axially" and "radially" relate to the axis of rotation of the rings of the rolling bearing one with respect to the other. A direction is "axial" when it is parallel to this axis and "radial" when it is perpendicular and secant with this axis. A rotation parameter of one part with respect to the other is a parameter which is representative of a pivoting movement of one part with respect to the other. Such a parameter can be an angle measuring the angular position of one part with respect to the other, around the central axis of the rolling bearing. Such a parameter can also be a speed, a displacement, an acceleration or a vibration.

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, taken in any technically admissible configuration:

- The electric connector is installed in a hole or a notch of the flange and has an inner side where the cable is connected and an outer side adapted to cooperate with a corresponding electrical connector or plug, in order to fulfill a connection function between the cable and an electric line including the corresponding electric connector.

- The electric connector has at least one sealing lip covering the edge of the hole or the notch. Advantageously, the electric connector has two sealing lips, each sealing lip covering the edge of the hole or notch on one side of the flange.

- The hole is circular and the edge of the hole is inserted in a peripheral circular groove of an insulative body of the connector.

- The notch extends up to one edge of the flange and at least a part of the edge of the notch is inserted in a peripheral groove of an insulative body of the connector.

The rolling bearing assembly includes an encoder washer fast in rotation with the inner ring, at least one sensor adapted to detect a rotation parameter of the encoder washer with respect to the flange and an annular body radially surrounding the outer ring of the rolling bearing in the housing and forming a support member for the sensor in a position where the sensor can detect a rotation parameter of the encoder washer. - The support member holds at least one printed circuit board and the electric cable extends between the electric connector and the printed circuit board.

- The annular body is made of a resilient material, preferably of a molded synthetic material.

- A cap is removably mounted on the flange, in a position where it covers at least the annular body, the sensor and the encoder washer.

- The electric cable extends directly between the electric connector and a sensor which belongs to the sensing means. The invention also concerns a device having a rotating shaft and equipped with a rolling bearing assembly as mentioned here-above, with the inner ring of the rolling bearing rotatably supporting the shaft. Such a device is more robust than the ones of the prior art. According to advantageous but non compulsory aspects, such a device might incorporate one or several of the following features, taken in any technically admissible configuration:

- The flange has an inner side facing an internal volume of the device and an outer side facing the outside of the device, whereas the electric cable of the connecting means extends between the electric connector and the sensing means on the inner side of the flange.

- The device includes a second connector sealingly mounted on the flange and a second electric cable connecting the second connector to electrical and/or electronical parts of the device different from the sensing means. According to a specially advantageous aspect of the invention, such a device can be an electric motor.

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 schematic partial axial cut view of an electric motor according to the invention provided with a rolling bearing assembly according to the invention;

- Figure 2 is an enlarged view of detail Il on figure 1 ;

- Figure 3 is a perspective view, partially cut away, of the rolling bearing assembly represented on figures 1 and 2;

- Figure 4 is a perspective view, at a larger scale, of an annular body belonging to the rolling bearing assembly of figure 3;

- Figure 5 is a schematic view similar to figure 1 for an electric motor and rolling bearing assembly according to a second embodiment of the invention; and

- Figure 6 is a partial side view in the direction of arrow Ai on figure 5. DETAILED DESCRIPTION OF SOME EMBODIMENTS

A motor 2 partly represented on figure 1 comprises a stator 4 and a rotor 6 provided with non-represented magnetically cooperating elements, in order to drive the rotor 6 in rotation around an axis X-X'.

Rotor 6 is mounted on and fixed in rotation with a shaft 8 centered on axis X-X'. Stator 4 is held in position around rotor 6 by a non-represented frame.

A flange 10 closes the overall housing of motor 2 and is provided with a central opening 12 for the passage of the shaft 8. Flange 10 is a boundary to the internal volume V₂ of motor 2. A ball bearing 20 is mounted on flange 10 and supports shaft 8 with a possibility of rotation around axis X-X'. Ball bearing 20 comprises an inner ring 22, an outer ring 24, several balls 26 and a cage 28 holding the balls in position between rings 22 and 24.

An encoder washer 30 is fixedly mounted on inner ring 22. This washer 30 comprises a metallic armature 32 having an inner radial collar 322 snapped within an annular groove 222 of ring 22. Encoder washer 30 also includes an active part

34 which is magnetized and defines, along its circumference, an alternation of

North poles and South poles, respectively formed by permanent magnets.

Alternatively to a magnetized washer, encoder washer 30 can include an active part made of a magnetic metal and provided with notches or holes. According to alternative embodiments, detection of the rotation of washer 30 can be performed by an inductive or optical sensor.

Outer ring 24 is received in a central recess 14 of flange 10 which is centered on axis X-X'. In other words, recess 14 is a housing accommodating the radial external portion of ball bearing 20.

An annular body 40 is mounted around outer ring 24. An annular body 40 is made of a molded synthetic material, for instance a polymeric material such as PA66 or PEAK, or a composite material comprising reinforcing fibers, such as glass fibers. This annular body is resilient. Alternatively, annular body 40 can comprise or be integrally made of metal, while being also resilient.

Annular body 40 comprises an annular skirt 42 which is introduced within housing 14, between the outer radial surface 242 of outer ring 24 and the peripheral surface 142 of housing 14. In other words, annular skirt 42 surrounds ball bearing 20 within housing 14 and this part of annular body 40 guarantees that the ball bearing 20 is radially correctly positioned with respect to the flange 10. Moreover, as it is resilient, skirt 42 can absorb vibrations due to a potential unbalance of rotor 6 and/or shaft 8. Annular skirt 42 can also absorb differential dilatations between flange 10 and ball bearing 20.

Annular body 40 also has an annular flat part 44 which is perpendicular to skirt 42 and extends perpendicularly to axis X-X' in the configuration of figure 1.

At the level of the respective inner edge 442 and outer edge 444 of part 44, two collars 46 and 48 extend with respect to part 44, in a direction opposite to skirt

42. An annular volume V₄₀ having a substantially U shaped cross section is defined by annular part 44, inner collar 46 and outer collar 48. Annular part 44 forms the base or bottom of the U section of volume V₄₀.

Annular part 44 is provided with four holes 446 evenly distributed around a central axis X₄₀ of annular body 40 which is superimposed with axis X-X' in the mounted configuration of the ball bearing assembly. U shaped guiding means 448 extend from the inner surface of collar 48 and define a channel for guiding the stem of a screw 80 towards each respective hole 446.

Annular body 40 also has a second annular flat part 49 which is parallel to part 44. Part 49 extends radially toward axis X₄O from the edge of inner collar 46 opposite to annular part 44.

Annular body is made of one piece: parts 42 to 49 are integral with each other.

A magnetic sensor 50, e.g. provided with a Hall effect cell, is fixedly mounted on the inner radial face 462 of inner collar 46. Sensor 50 can be glued or otherwise fixed on annular body 40 and parts 44 to 49 form together a support member for sensor 50, this support member being held in position with respect to flange 10 by the cooperation of housing 14, ball bearing 20 and skirt 42.

This sensor 50 is connected by a non represented electrical cable to a printed circuit board 60 or "PCB" installed within volume V₄₀. This PCB 60 is flat and in the form of an annulus perpendicular to axis X-X'. A passage 464 is provided through inner collar 46 for cable 52. A metallic cap or cover 70 is used to protect parts 30 to 60 and has a main flat portion 72, an inner edge portion 74 and an outer edge portion 76 adapted to surround radially, respectively inwardly and outwardly, parts 30 and 40.

Flat portion 72 is also provided with four holes which are supposed to be aligned with the four holes 446 of annular body 40 so that four screws 80 can be inserted simultaneously within these holes and within threaded holes 16 provided in flange 10.

Screws 80 firmly and reversibly immobilize annular body 40 and cap 70 with respect to flange 10. The axial position of annular body 40 with respect to flange 10 is used to immobilize ring 24 within housing 14.

PCB 60 is connected to a first end 101 of an electric cable 100 whose second end 102 is connected to an electrical connector or plug 110 installed within a hole 18 made in flange 2. Hole 18 is circular and its edge 182 is inserted in a peripheral circular groove 112 provided on the outer radial face of the insulating body 114 of electrical connector 110. Body 114 forms two annular sealing lips 116 and 118 and groove 112 is defined between these two lips.

Body 114 is provided with non represented electrically conducting parts which are respectively connected to the electrical wires contained in cable 100.

A hole 78 is provided in outer portion 76 for the passage of cable 100. Another hole 484 is provided in collar 48 for the passage of cable 100 towards volume V₄₀.

Flange 10 has an inner side 13 oriented towards volume V₂ and an outer side 15 which is accessible from outside motor 2. Similarly, electrical connector 110 has an inner side formed by body 114 and oriented towards volume V₂ and an outer side also formed by body 114 and accessible from outside flange 10.

Sealing lip 116 covers edge 182 on the inner side 13 of flange 10, whereas lip 118 covers edge 182 on the outer side 15 of flange 10. Thanks to lips 116 and 118, electric connector 110 is sealingly mounted through flange 10.

According to a non represented embodiment of the invention, body 114 can be provided with one sealing lip only which is located either on the inner side 13 or on the outer side 15 of flange 10 and covers the edge of hole 18. Since it is located within the internal volume V₂ of motor 2, cable 100 is protected from shocks, cutting tolls and non appropriate efforts. In particular, cable 100 does not risk to be cut or separated from PCB 60 by a pulling effort.

A second electric cable 200 has a first end 201 provided with an electrical plug or connector 210 which is complementary to connector or plug 110 and can be plugged onto this connector from the outer side 15 of flange 10. An electronic control unit (ECU) 220 is connected to the second end 202 of cable 200. ECU 220 is connected by non represented means to a voltage source. Therefore, when connectors 110 and 210 are plugged one onto the other, ECU 220 constitutes a voltage supply source for PCB 60 and sensor 50. ECU 220 is also adapted to receive and treat electronic signals generated by PCB 60 and representative of a rotation parameter detected by sensor 50, such as the rotation speed of encoder washer 30. Other signals, representative of other parameters, such as temperature or humidity, can be sent to the ECU via the cables 110 and 210. In case of damage on cable 200 or connector 210, the electric line 230 formed by these two elements can be easily replaced, without having to access the inside volume V₂ of motor 2.

Moreover, since cable 200 does not go through flange 10, it is not necessary to install on flange 10 some sealing means dedicated to this cable. Annular body 40 is efficient to immobilize ball bearing 20 with respect to flange 10 both axially and radially with respect to axis X-X' thanks to parts 42 and 44. On the other hand, parts 44 to 49 form a support member or section of body 40 which is integral with annular skirt 42 and extends outside housing 14 in such a way that it holds sensor 50 and PCB 60 in a position where they can fulfill their respective functions.

In other words, a single part, namely annular body 40, is used to hold the ball bearing 20 in position with respect to the flange 10 and the sensor 50 in position with respect to the encoder washer 30. This induces that the rolling bearing assembly formed by items 10, 20, 30, 40, 50, 60, 70, 80, 100 and 110 is compact, in particular along an axial direction, as compared to existing assemblies.

Because of the geometry of annular body 40, PCB 60 can be installed "radially", that is in a plane which is perpendicular to axis X-X', so that it can have a relatively large surface, without having a negative influence on the axial compactness of rolling bearing assembly 10-80 and of motor 2.

For the clarity of the figures, the electronic components mounted on PCB 60 are not represented. As shown on the figures, PCB 60 is annular and extends over 360°around axis X-X'. This is not compulsory and P CB 60 can extend on a limited angular sector around axis X-X', e.g. 90° or even l ess. This is advantageous insofar as the axial dimensions of the stator 4 vary around axis X-X', so that rolling bearing assembly 10-80 can be integrated into motor 2 in a configuration such that PCB 60 is located in front of a part of stator 4 which is relatively short along axis X- X'. This allows to mount rolling bearing assembly 10-80 very close to stator 4, without interference between these items.

Since PCB can be relatively large because of the size of volume V₄₀, it can also support electronic components used to control motor 2 and which are not functionally connected to sensor 50. In other words, a sort of an electronic control unit (ECU) can be made within ball bearing assembly 10-80 to control sensor 50 and other electronic parts of motor 2, without substantially increasing its volume, in particular its axial volume. Other ECUs of motor 2 can be reduced or even suppressed.

Once flange 10 is removed from the remaining part of motor 2, easy access to PCB 60 is provided insofar as, as soon as screws 80 and cover 70 have been removed, one can work on PCB 60 without having to further disassemble the rolling assembly. In particular, work can be done on PCB 60 without moving sensor 50 with respect to encoder washer 30 and without removing rolling bearing 20 from its housing 12. Therefore, serviceability of the ball bearing assembly 10-80 of the invention is improved.

In the second embodiment of the invention represented on figures 5 and 6, the elements similar to the ones of the first embodiment have the same references. Hereafter, one describes mainly the differences between this embodiment and the first embodiment. A flange 10 forms a housing 14 for partly receiving a ball bearing 20 having an inner ring 22, an outer ring 24, balls 26 and a cage 28, as in the first embodiment. A moulded plastic ring 40 is installed around ball bearing 20 within housing 14. Ball bearing 20 supports a shaft 8 with a possibility of rotation around an axis X-X'. This shaft is fast in rotation with a rotor 6 surrounded with a stator 4 located in the inside volume V₂ of an electric motor 2, this volume being limited by flange 10.

An encoder washer 30 is made of a metallic armature 32 and an active part 34. This encoder washer is fast in rotation with inner ring 22. A support member 140 is mounted on flange 10 by screws 180 represented by their respective axes. Support member 140 holds a sensor 50 axially aligned on washer 30 and which is connected to a first end 101 of a cable 100 whose second end 102 is connected to an electrical connector 110 similar to the one of the first embodiment. This connector is engaged in a notch 118 provided in flange 10 and which extends up to an edge 17 of this flange, so that the body 114 of connector 10 can be installed within notch 118 by a translation in the direction of arrow A₂ on figure 6. Body 114 is provided with two sealing lips 116 and 118 which cover a part of the edge 1182 of notch 118. A non represented stopper is used to close the part of notch 118 which is not obturated by body 114. The stopper can also hold, in operating position, the body 114 inside the notch. Alternatively, the shape of body 114 is adapted to the shape of notch 118 so that body 114 fully fills notch 118 when it is installed on flange 10.

As in the first embodiment, an electric line 230 is formed of an electric cable 200 and an electric connector 210 and, when connectors 210 and 110 are plugged together, this electric line connects connector 110 to an electronic control unit 220 which includes electronic components necessary to makes sensor 50 work correctly. No PCB similar to the PCB 60 of the first embodiment is used here. All control components of sensor 50 are integrated within ECU 220.

An electronic connector 310 similar to connector 110 is mounted in a hole 18' of flange 10. This electronic connector 310 is connected to stator 4 by an electric cable 300. On the other hand, an electric line 330 is formed outside of volume V₂ by an electric cable 400 and a connector 410 complementary to connector 310. Cable 400 is connected to a voltage source 420 so that, when connectors 310 and 410 are plugged one onto the other, an electric current can be provided to stator 4. Alternatively, connector 310 can be used to provide a non represented ECU housed within volume V₂ with voltage and/or electronic signals. According to a non represented embodiment of the invention, a single connector can be used in order to connect both sensor 50 and stator 4 and/or an ECU to the outside environment of motor 2.

According to an aspect of the invention which relates to all embodiments, since the connector 110 or the connectors 110 and 310 are sealingly mounted on the flange 10, sensor 50 does not have to be concealed in a sealed casing within volume V₂.

The invention has been described in the case when one sensor 50 is used. Alternatively, several sensors can be used, these sensors being held in position by annular body 40 or by support member 140. The invention is applicable irrespective of the actual geometry of the flange 10. The invention is particularly interesting for electric motors. However, it can also be used for other mechanical or electromachanical devices like gearboxes.

Any kind of rolling bearing can be used with the invention.

Claims

1. A rolling bearing assembly (10-110) comprising:

- a rolling bearing (20) with an inner ring (22), an outer ring (24) and rolling bodies (26) between the inner and outer rings,

- a flange (10) with a housing (14) where the rolling bearing is at least partially received,

- sensing means (50, 60) adapted to detect a rotation parameter of one of the rings (22) with respect to the other (24), and - electric connecting means (100-110) adapted to connect the sensing means to voltage supply means (220) and/or to an electronic control unit (220), wherein the electric connecting means include an electric connector (110) sealingly mounted through the flange (10) and an electric cable (100) connecting the electric connector to the sensing means (50, 60).

2. Rolling bearing assembly according to claim 1 , wherein the electric connector (110) is installed in a hole (18) or a notch (118) of the flange (10) and has an inner side (113) where the cable (100) is connected and an outer side (115) adapted to cooperate with a corresponding electrical connector or plug (210) in order to fulfill a connection function between the cable (100) and an electric line (230) including the corresponding electric connector (210).

3. Rolling bearing assembly according to claim 2, wherein the electric connector (110) has at least one sealing lip (116, 118) covering the edge (182,

1182) of the hole (18) or the notch (118).

4. Rolling bearing assembly according to claim 3, wherein the electrical connector (110) has two sealing lips (116, 118), each sealing lip covering the edge (182, 1182) of the hole (18) or notch (118) on one side (13, 15) of the flange.

5. Rolling bearing assembly according to one of claims 2 to 4, wherein the hole (18) is circular and the edge (182) of the hole is inserted in a peripheral circular groove (112) of an insulative body (114) of the connector (110).

6. Rolling bearing assembly according to one of claims 2 to 4, wherein the notch (118) extends up to one edge (17) of the flange (10) and at least a part of the edge (1182) of the notch is inserted in a peripheral groove (112) of an insulative body (114) of the connector (110).

7. Rolling bearing assembly according to any one of the previous claims, wherein it includes:

- an encoder washer (30) fast in rotation with the inner ring (22),

- at least one sensor (50) adapted to detect a rotation parameter of the encoder washer with respect to the flange (10), and - an annular body (40) radially surrounding the outer ring (24) of the rolling bearing (20) in the housing and forming a support member (44-49) for the sensor in a position where the sensor can detect a rotation parameter of the encoder washer.

8. Rolling bearing assembly according to claim 7, wherein the support member (44-49) holds at least one printed circuit board (60) and the electric cable (100) extends between the electric connector (110) and the printed circuit board.

9. Rolling bearing assembly according to one of claims 7 or 8, wherein the annular body (40) is made of a resilient material, preferably of a molded synthetic material.

10. Rolling bearing assembly according to one of claims 7 to 9, wherein a cap (70) is removably mounted on the flange (10), in a position where it covers at least the annular body (40), the sensor (50) and the encoder washer (30).

11. Rolling bearing according to any one of claims 1 to 6, wherein the electric cable (100) extends directly between the electric connector (110) and a sensor (50) which belongs to the sensing means.

12. A device (2) with a rotating shaft (8), wherein said device is equipped with a rolling bearing assembly (10-110) according to any one of the previous claims, wherein the inner ring (22) rotatably support the shaft (8).

13. Device according to claim 12, wherein the flange (10) has an inner side (13) facing an internal volume (V₂) of the device (2) and an outer side (15) facing the outside of the device and wherein the electric cable (100) extends between the electric connector (110) and the sensing means (50, 60) on the inner side of the flange.

14. Device according to any one of claims 12 and 13, wherein it includes a second connector (310) sealingly mounted on the flange (10) and a second electric cable (300) connecting the second connector to electrical and/or electronical parts (4) of the device different from the sensing means (50).

15. Device according to any one of claims 12 to 14, wherein it constitutes an electric motor (2).