WO2010139505A1

WO2010139505A1 - An instrumented bearing assembly, a device for detecting rotation of a wheel including such an assembly, and a method of fabricating such an assembly

Info

Publication number: WO2010139505A1
Application number: PCT/EP2010/055217
Authority: WO
Inventors: Sylvain Chaussat
Original assignee: Aktiebolaget Skf
Priority date: 2009-06-02
Filing date: 2010-04-20
Publication date: 2010-12-09
Also published as: FR2946107A1; FR2946107B1

Abstract

The instrumented bearing assembly (10) comprises an outer ring (22); an inner ring (24); and detector means (50) for detecting a rotation parameter of the outer ring relative to the inner ring. The instrumented bearing assembly (10) further comprises: first and second annular spacers (80, 90) disposed on either side of the inner ring (24), the first spacer (80) defining a housing for a sensor (52) forming part of the detector means, and the second spacer (90) defining a housing (92) for electronic components (54) and/or electrical connector means (58) associated with the sensor. At least one member (100) exerts a clamping force on the two spacers (80, 90) to clamp the inner ring (24) between the spacers (80, 90).

Description

AN INSTRUMENTED BEARING ASSEMBLY, A DEVICE FOR DETECTING

ROTATION OF A WHEEL INCLUDING SUCH AN ASSEMBLY, AND A

METHOD OF FABRICATING SUCH AN ASSEMBLY

The present invention relates to an instrumented bearing assembly as used for example in order to detect the speed of rotation of a wheel of a cycle, in particular a motorcycle or a bicycle. The invention also relates to a detector device for detecting at least one rotation parameter of a wheel, e.g. a cycle wheel, and to a method of fabricating an instrumented bearing assembly as mentioned above.

FR-A-2 871 881 discloses detecting rotation parameters of a wheel by means of an instrumented sensor mounted on an axle of the wheel between one arm of a fork and a rotary hub of the wheel . That instrumented bearing is not used for supporting the wheel relative to a central axle, but is added on one side of the hub, thereby increasing the axial size of the central portion of the wheel. In addition, the encoder washer that is constrained to rotate with the outer ring of the instrumented bearing is situated axially on the outside of the bearing so that the corresponding sensor is also situated on the outside so as to enable it to be connected to external means for recording and/or displaying the measured speed. As a result, the means for detecting the rotation of the wheel are exposed to bad weather and pollution, and that is likely to reduce the lifetime of the bearing. Furthermore, in known systems, spacers are sometimes associated with the instrumented bearing and the spacers need to be installed together with the bearing, e.g. in the hub of a motorcycle wheel, thus requiring qualified labor and running the risk of being lost, in particular in the event of the wheel being disassembled during a maintenance operation. The present invention seeks more particularly to remedy those drawbacks by proposing a novel instrumented bearing assembly that enables a rotation parameter of one of its rings to be detected effectively and that is suitable for being handled in a manner that is particularly practical, thereby facilitating both initial putting into service, and subsequent maintenance operations .

To this end, the invention relates to an instrumented bearing assembly comprising: an outer ring; an inner ring; and detector means for detecting a rotation parameter of the outer ring relative to the inner ring. This bearing assembly further comprises first and second annular spacers disposed on either side of the inner ring, the first spacer defining a housing for a sensor forming part of the detector means, and the second spacer defining a housing for electronic components and/or electrical connector means associated with the sensor. Finally, the bearing assembly comprises at least one member suitable for exerting a clamping force on the two spacers to clamp the inner ring between the spacers .

By means of the invention, the two spacers disposed on either side of the rings of the bearing enable the sensor and the associated detector washer to be installed on a side of the bearing that is relatively protected, whereas the connection means are disposed on another side, in particular on the outside, so as to enable them to interact with a processor or display unit. The two spacers thus serve to distribute the means for detecting the rotation parameter on both sides of the rings of the bearing. Furthermore, the member that exerts a clamping force ensures that the assembly constituted by the bearing and the two spacers constitutes an entity that is easy to handle, in particular for insertion inside a hollow volume such as the hub of a cycle wheel. According to aspects of the invention that are advantageous but not essential, such an instrumented bearing assembly may incorporate one or more of the following characteristics taken in any technically feasible combination:

• A plurality of members distributed around the axis of rotation of the outer ring are suitable for exerting a clamping force on the two spacers to clamp the inner ring between the spacers . • The above-mentioned member (s) extend (s) in part radially inside the inner ring and the radially inner surface of the inner ring is provided with at least one housing for receiving a portion of said member that extends axially in register with said ring. • The above-mentioned member is elastically deformable and its axial dimension and the axial dimensions of the two spacers and of the inner ring are such that said member is deformed elastically while it is put into place on the spacers, such that the clamping force is elastic.

• The above-mentioned member is a metal clip having an elongated central portion and two bent-back ends for applying the clamping force against the spacers. Each of these ends is advantageously provided with a respective tongue for hooking in a housing formed in a face of each spacer that faces away from the inner ring.

• The above-mentioned member extends radially inside the spacers and the radially inner surface of each spacer is provided with a respective housing for receiving a fraction of said member that extends axially in register with the spacer.

• The fraction of each member that is received in the housing of the inner ring or of a spacer does not project radially inwards relative to the radially inner surface of the inner ring or the spacer.

The invention also provides a detector device for detecting at least one rotation parameter of a wheel, in particular a cycle wheel, the device comprising a bearing assembly as mentioned above interposed between a hub of the wheel and an axle forming a support for the wheel and engaged in the hub . Finally, the invention provides a method of fabricating a bearing assembly such as that mentioned above, and more particularly a fabrication method comprising the steps consisting in: a) assembling a bearing comprising at least an outer ring and an inner ring; b) securing a encoder washer to the outer ring; c) placing on opposite sides of the inner ring, firstly a sensor suitable for detecting rotation of the coder washer, and secondly electronic components and/or electrical connection means associated with the sensor; d) placing two spacers on opposite sides of the inner ring, the first spacer being provided with a housing for receiving the sensor, and the second spacer being provided with a housing for receiving the electronic components and/or the electrical connection means; and e) installing on the stack formed by the bearing and the two spacers at least one member that exerts a clamping force on the spacers for clamping the inner ring between the spacers .

The invention can be better be understood and other advantages thereof appear more clearly in the light of the following description of an embodiment of a bearing assembly and a detector device in accordance with the principle of the invention, given purely by way of example and described with reference to the accompanying drawings, in which:

^• Figure 1 is an axial section of the assembly zone of a motorcycle wheel on a support axle; • Figure 2 is a view on a larger scale of a support axle and a bearing assembly used in the Figure 1 mounting;

• Figure 3 is a section on a smaller scale on line III-III of Figure 2, with the support axle omitted;

• Figure 4 is a section on line IV-IV of Figure 3;

• Figure 5 is a perspective view from a first viewing angle of a bearing assembly in accordance with the invention; • Figure 6 is a perspective view of the same bearing assembly viewed from another angle; and

• Figure 7 is a longitudinal section on a larger scale of a clip used in the bearing assembly of Figures 2 to 6. In Figure 1, a motorcycle wheel, represented solely by its hub 2, is supported by an axle 4 that is held in place by the two arms 6 of a fork.

A ball bearing 8 is interposed between the hub 2 and the axle 4 close to one of the two arms 6, while an instrumented bearing assembly 10 is interposed between the hub 2 and the axle 4 close to the other arm of the fork 6.

Two nuts 11 are screwed onto the threaded ends of the axle 4 and they exert a force E₁ tending to move the arms of the fork 6 towards each other.

A tubular spacer 12 is mounted between the bearing 8 and the assembly 10, around the axle 4.

The bearing assembly 10 serves both to support the hub 2 so as to enable it to revolve about the axle 4, and also to detect a parameter representative of the rotation of the hub .

The bearing assembly 10 can be seen more particularly in Figures 2 to 6 and comprises an outer ring 22, an inner ring 24, and six balls 26 that are held in place between the rings 22 and 24 by a cage 28. Two raceways 222 and 242 are defined respectively on the radially inner surface of the ring 22 and the radially outer surface of the ring 24 for receiving the balls 26.

An encoder washer 30 is formed by an armature 32 and a magnetic ring 34 mounted on the plate. The magnetic ring 34 defines at least two opposite magnetic poles formed by permanent magnets.

The armature 32 is made of metal and it is clipped around the ring 22, at the level of an outside edge 224 of the ring. Thus, the elements 22 and 30 are constrained to rotate together about an axis X₁₀ that is a central axis of the bearing assembly 10 and coincides with the axes of symmetry of the rings 22 and 24. The longitudinal axis X₄ of the axle 4 coincides with the axis X₁₀ when the bearing assembly 10 is in its configuration mounted on the axle 4.

Two gaskets 25 and 27 extend respectively between the rings 22 and 24 and isolate from the outside the rolling chamber in which the balls 26 are received between the raceways 222 and 242. A detector device 50 for detecting a rotation parameter of the outer ring 22 relative to the inner ring 24 also forms part of the bearing assembly 10. A rotation parameter of the outer ring 22 relative to the inner ring 24 is a parameter representative of the rotary movement of the outer ring relative to the inner ring.

One such parameter may be an angle specifying the angular position of the outer ring relative to the inner ring about the axis X₁₀. Another such parameter may also be a speed, a movement, an acceleration, or a vibration. The detector device 50 comprises a sensor 52 placed facing the magnetic ring 34, radially inside it.

In the present description, the terms "axial", "radial", "axially", and "radially" are relative to the axis X₁₀ of rotation of the rings 22 and 24 relative to each other. A direction is said to be "axial" when it is parallel to said axis and "radial" when it is perpendicular to said axis and intersects it. The detector device 50 also comprises an integrated circuit 54 supporting electronic components 56 suitable for processing a signal emitted by the sensor 52. The device 50 also has a connector 58 secured to the circuit 54 and serving to receive a plug (not shown) mounted at the end of a cable 14 for connecting the detector device 50 to an electronic unit (not shown) for processing and/or displaying the value of the rotation parameter detected by the assembly 10. Reference P₁₀ designates a plane that is radial relative to the axis X₁₀ and that contains the centers of the balls 26. Figure 3 is a section in the plane P₁₀.

The sensor 52 is disposed on one side of the plane P₁₀, while the elements 54 to 58 are disposed on the other side of said plane, the plane P₁₀ being substantially equidistant between the elements 52 on one side and the elements 54 to 58 on the other. To make this configuration possible, three connection pins 53 connect the sensor 52 to the integrated circuit 54 and extend parallel to the axis X₁₀, axially along the inner ring 24.

By means of this disposition, the encoder washer 30 and the sensor 52 are positioned, relative to the bearing 29 constituted by the elements 22 to 28 on one side of this bearing that is situated on the inside of the central volume V₂ of the hub 2, whereas the elements 54 to 58 are situated outside said volume, thereby making it easier to connect the plug at the end of the cable 14.

For this purpose, a groove 244 is formed in the radially inner surface 246 of the ring 24 in order to pass the pins 53.

A covering 60 of synthetic material is molded onto the detector device 50. References 62, 63, 64, and 68 designate the respective portions of the covering 60 that surround the portions 52, 53, 54, and 58 of the detector device 50. The groove 244 is dimensioned to receive both the pins 53 and the portion 63 of the covering 60. A first annular spacer 80 is mounted on the inside of the bearing 29, i.e. beside the volume V₂. The spacer 80 defines a housing 82 for receiving the sensor 52 and the portion 62 of the covering 60. A second annular spacer 90 is mounted on the opposite side of the bearing 29, i.e. on the other side of the plane P₁₀ relative to the spacer 80. The spacer 90 is thus situated outside the volume V₂. It defines a housing 92 for receiving the elements 54 to 58 and the portions 64 to 68 of the covering 60. The housing 92 passes through the spacer 90 so that an opening 93 gives access to the connector 58 through the spacer 90.

The spacers 80 and 90 enable the elements 52 to 58 constituting the detector device 50 to be positioned facing the bearing 29 and to be protected mechanically, and they also serve to transmit the clamping force E₁ exerted by the nuts 11 on the arms of the fork 6 against the bearing 8 and the bearing assembly 10, this clamping force having the effect of pressing the elements 8 and 10 against the central spacer 12.

Two identical clips 100 are provided for connecting the spacers 80 and 90 to the bearing 29. Each clip 100 is formed by cutting out and folding a strip of spring steel and has an elongate central portion 102 with two bent-back ends 104 and 106 having respective tongues 108 and 110 cut out therein.

The ends 104 and 106 are bent back towards the same side of the portion 102 and the tongues 108 and 110 project towards each other from the ends 104 and 106. Furthermore, in its face 84 facing away from the bearing 29 in the mounted configuration of the assembly 10, the spacer 80 is provided with two housings 86, each serving to receive one end 104 or 106 of a clip 100, without the clip projecting relative to the remainder of the surface 84. Each housing 86 is provided with a setback 87 for receiving a tongue 108 or 110 when an end 104 or 106 is placed in the housing 86. In the radially inner surface 88 of the spacer 80, each housing 86 is extended by a groove 89 that forms a housing for receiving a fraction 102A of the portion 102 that extends axially through the spacer 80 when the clip 100 is mounted in the spacers 80 and 90.

Thus, two grooves 89 are provided in the surface 88, these grooves being diametrically opposite relative to the axis X₁₀. Reference e₁₀₂ designates the radial thickness of the portion 102 of the clip 100, i.e. the smallest dimension of the portion 102 that is constituted by a general plane strip. The radial depth of the grooves 89 is slightly greater than the radial thickness e₁₀₂. Thus, each portion 102A of a clip 100 does not project radially towards the axis X₁₀ relative to the surface 88 in the mounted configuration of the clip 100 in the spacer 80.

The radially inner surface 246 of the ring 24 is also provided with two diametrically opposite grooves 249 that serve to accommodate a middle fraction 102B of the portion 102 of each clip 100, without said fraction 102B projecting radially inwards relative to the surface 246. The radial depth of the grooves 249 is likewise greater than the thickness e₁₀₂.

In its outside face 94 facing away from the bearing 29 in the mounted configuration of the assembly 10, the spacer 90 is provided with two housings 96 of shape analogous to the housings 86 and each provided with a setback 97 for receiving a tongue 108 or 110 located at one of the ends 104 or 102 of a clip 100 received in these housings. The radially inner surface 98 of the spacer 90 is provided with two grooves 99 that extend the housings 96 and that serve to receive a fraction 102C of the portion 102 that is disposed axially in register with the spacer 90 in the mounted configuration of the bearing assembly 10. The radial depth of grooves is greater than the thickness e₁₀₂ so that the fractions 102C of the clips 100 do not project radially inwards relative to the surface 98 when these fractions 102 are in position in the grooves 99.

The assembly 10 is assembled initially by assembling the bearing 29 using a known technique that comprises, in particular, putting the balls 26 and the cage 28 into place in the rolling chamber and then putting the gaskets 25 and 27 into place between the rings 22 and 24. The coder washer 30 is then fitted on the outer ring 26 and secured thereto by a centripetal force exerted by the plate 32 on the edge 224 of the ring 22.

The detector device 50, previously fitted with its covering 60 is then put into place in such a manner that the sensor 52 is brought into register with the ring 34, being situated radially inside it, beside the gasket 27 relative to the plane P₁₀, while the elements 54 to 58 are situated beside the gasket 25, i.e. on the other side of the plane P₁₀, the pins 53 and the corresponding portion 63 of the covering 60 being received in the groove 244 of the ring 24. Thereafter the spacers-rings 80 and 90 are fitted on either side of the bearing 29 by engaging the sensor 52 and the portion 62 of the covering 60 in the housing 82 of the spacer-ring 80 and also by engaging the elements 54 and 58 and the portions 64 and 68 of the covering 60 in the housing 92 of the spacer-ring 90, taking care to put the connector 58 in register with the opening 93. This constitutes a stack made up of the parts and subassemblies 29 - 30 - 50 - 60 - 80 - 90, which stack is suitable for being subjected to an axial force such as the force E₁.

The two clips 100 are then introduced into the central volume of the previously-constituted stack 29 - 30 - 50 - 60 - 80 - 90 until the ends 104 and 106 of each clip 100 are brought into register with the housings 86 and 96 in the spacers 80 and 90. The clips 100 are then moved radially away from the axis X₁₀, thereby bringing the ends 104 and 106 into the housings 86 and 96 and bringing the tongues 108 and 110 into the setbacks 87 and 97. Inserting the tongues 108 and 110 into the setbacks 87 and 97 hooks the clips 100 to the spacers 80 and 90, thereby preventing the clips 100 from sliding towards the axis X₁₀. In other words, the tongues 108 and 110 and the setbacks 87 and 97 ensure that the clips 100 are held captive once they have been mounted on the spacers 80 and 90 of the above-mentioned stack.

This centrifugal movement of the clips 100 relative to the axis X₁₀ has the effect of engaging their central portions 102 in the grooves 89, 249, and 99 that were previously put into alignment. The fractions 102A, 102B, and 102C of the central portion 102 of each clip are engaged respectively in the grooves 89, 249, and 99. The fractions 102A, 102B, and 102C all have the same thickness e₁₀₂ and they do not project towards the axis X₁₀ from the surfaces 88, 246, and 98, respectively.

References L₂₄, L₈₀, and L₉₀ designate respectively the axial lengths of the ring 24 and of the spacers 80 and 90. The axial length L of the stack 29 - 30 - 50 - 60 - 80 - 90 is equal to the sum of the lengths L₂₄, L₈₀, and L₉₀.

The axial length L₁₀₀ of each clip 100 is determined relative to the axial length L of the stack in such a manner that putting the ends 104 and 106 into place in housings 86 and 96 has the effect of putting each clip 100 into tension, to such an extent that the ends 104 and 106 elastically exert an axial force E₂ on the spacers 80 and 90, thereby having the effect of pressing the spacers 80 and 90 against the ring 24, which is thus clamped between said spacers. In other words, the clips enable the bearing 29 to be clamped between the spacers 80 and 90, thus constituting a bearing assembly 10 that can be handled as a single piece when it has to be put into place between the hub 2 and the axle 4 or when it needs to be removed during a subsequent maintenance operation. This unitary bearing assembly 10 greatly facilitates the work of an operator, e.g. during manufacture of a motorcycle .

The force E₂ thus enables the stack 29 - 30 - 50 - 60 - 80 - 90 to conserve its unitary or "one-piece" nature before it is put into place around the axle 4 or after it is removed therefrom.

Since the central portion 102 of the clips 100 are received in the grooves 89, 99, and 249 formed respectively in the first and second spacers 80 and 90 and in the inner ring 24, without projecting radially inwards relative to the respective radially inner surfaces 88, 98, and 246, these clips do not hinder putting the bearing assembly 10 into place on the axle 4, and they remain in place after the bearing assembly 10 has been installed on the axle 4.

The use of the bearing assembly 10 as a cycle tachometer is particularly advantageous given the simplicity with which this bearing assembly can be handled and put into place, and because the sensor 52 and the coder ring 30 are protected from the outside by the bearing 29 itself.

The invention is described above in the context of a ball bearing. Nevertheless, it is also applicable to bearings having other rolling bodies, in particular to roller bearings or to needle bearings, and also to smooth bearings .

Claims

1. An instrumented bearing assembly (10) comprising:

• an outer ring (22) ; • an inner ring (24) ; and

• detector means (50) for detecting a rotation parameter of the outer ring relative to the inner ring; the assembly being characterized in that it further comprises : • first and second annular spacers (80, 90) disposed on either side of the inner ring (24), the first spacer (80) defining a housing (82) for a sensor (52) forming part of the detector means, and the second spacer (90) defining a housing (92) for electronic components (54, 56) and/or electrical connector means (58) associated with the sensor; and

• at least one member (100) suitable for exerting a clamping force (E₂) on the two spacers (80, 90) to clamp the inner ring (24) between the spacers.

2. A bearing assembly according to claim 1, characterized in that it includes a plurality of members (100) distributed around the axis of rotation (X₁₀) of the outer ring (22) and suitable for exerting a clamping force (E₂) on the two spacers (80, 90) to clamp the inner ring (24) between the spacers .

3. A bearing assembly according to any preceding claim, characterized in that the member (100) extends in part radially inside the inner ring (24) and the radially inner surface (246) of the inner ring is provided with at least one housing (249) for receiving a portion (102B) of said member that extends axially in register with said ring .

4. A bearing assembly according to any preceding claim, characterized in that the member (100) is elastically deformable and its axial dimension (L₁₀₀) and the axial dimensions (L₂₄, L₈₀, L₉₀) of the two spacers (80, 90) and of the inner ring (24) are such that said member is deformed elastically while it is put into place on the spacers, such that the clamping force (E₂) is elastic.

5. A bearing assembly according to any preceding claim, characterized in that the member (100) is a metal clip having an elongate central portion (102) and two bent- back ends (104, 106) for applying the clamping force (E₂) against the spacers (80, 90) .

6. A bearing assembly according to claim 5, characterized in that each end (104, 106) of the clip (100) is provided with a respective tongue (108, 110) for hooking in a housing (86, 96) formed in a face (84, 94) of each spacer that faces away from the inner ring (24) .

7. A bearing assembly according to any preceding claim, characterized in that the member (100) extends radially inside the spacers (80, 90) and the radially inner surface (88, 98) of each spacer is provided with a respective housing (89, 99) for receiving a fraction (102A, 102C) of said member that extends axially in register with the spacer.

8. A bearing assembly according to claim 3 or claim 7, characterized in that the fraction (102A, 102B, 102C) of each member (100) that is received in the housing (89, 99, 249) of the inner ring (24) or of a spacer (80, 90) does not project radially inwards relative to the radially inner surface (88, 98, 246) of the inner ring or the spacer.

9. A detector device for detecting at least one rotation parameter of a wheel, in particular a cycle wheel, the device comprising a bearing assembly (10) according to any preceding claim interposed between a hub (2) of the wheel and an axle (4) forming a support for the wheel and engaged in the hub .

10. A method of fabricating a bearing assembly, the method being characterized in that it comprises the steps consisting in: a) assembling a bearing (29) comprising at least an outer ring (22) and an inner ring (24) ; b) securing an encoder washer (30) to the outer ring; c) placing on opposite sides of the inner ring, firstly a sensor (52) suitable for detecting rotation of the encoder washer (30) , and secondly electronic components (54-56) and/or electrical connection means (58) associated with the sensor (52) ; d) placing two spacers (80, 90) on opposite sides of the inner ring, the first spacer (80) being provided with a housing (82) for receiving the sensor (52), and the second spacer (90) being provided with a housing (92) for receiving the electronic components (54-56) and/or the electrical connection means (58) ; and e) installing on the stack formed by the bearing (29) and the two spacers (80, 90) at least one member (100) that exerts a clamping force (E₂) on the spacers for clamping the inner ring (24) between the spacers .