Inductive position sensor with shielding system

Abstract

The present invention relates to an inductive position sensor (1) for a rotating electrical machine comprising a plastic housing (30) in which is disposed a printed circuit board having at least one transmitting element for emitting an oscillating magnetic field, and at least one receiving device for detecting a modified magnetic field, the sensor comprising a shielding system (50) formed by at least one shielding piece (51) assembled on the outer surface of the plastic housing (30) by a fastening element (52) inserted into an opening (53). Fig. 1.

Description

Title of the invention: Inductive position sensor with shielding system

[0001] The present invention relates to the field of position sensors, and more particularly to an inductive position sensor comprising an improved shielding system.

[0002] Eddy current inductive position sensors, as described in patent application FR3128067A1, use an oscillating magnetic field to determine the angular position of a rotating target which forms a coupling element.

[0003] These position sensors are notably used in electric motors of electric or hybrid vehicles comprising a rotor rotating relative to a stator.

[0004] The angular position of the rotor is determined relative to the stator. The target is mounted at the end of, or through, a shaft of the rotor to modify an oscillating magnetic field transmitted by a transmitter. The target is centered with respect to an axis of rotation of the rotor. The target comprises several vanes that provide a magnetic field pattern with respect to the axis of rotation of the rotor.

[0005] The position sensor is fixed relative to the stator, facing the target and around or facing the end of the rotor. The position sensor comprises a printed circuit board (PCB) having at least one emitting element for emitting an oscillating magnetic field towards the target, generating a modified oscillating magnetic field at a given frequency.

[0006] The printed circuit board includes at least one receiving device for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit provided on the printed circuit board to deduce the angular position of the target.

[0007] All the elements are arranged in a plastic case.

[0008] This type of sensor with a plastic housing is usually used to seal the engine casing, which creates a metallic discontinuity in the engine casing and can disrupt the operation of the sensor assembly, engine, and other electrical components of the vehicle.

[0009] One solution is to use a shielding piece. Usually this shielding piece is fixed with a complex device in the plastic housing and requires a specific shape both in the plastic housing and the shielding piece.

[0010] One of the disadvantages of this type of sensor stems from the difficulty and cost of manufacturing these specific shapes.

[0011] The present invention therefore aims to overcome one of the drawbacks of those of the prior art by proposing a position sensor comprising a shielding piece whose attachment is simplified and improved.

[0012] For this purpose, the present invention proposes an inductive position sensor for a rotating electrical machine comprising a plastic housing in which is disposed a printed circuit board having at least one emitting element intended to emit an oscillating magnetic field, and at least one receiving device intended to detect a modified magnetic field, the sensor comprising a shielding system formed by at least one shielding piece assembled on the outer surface of the plastic housing.

[0013] Such a sensor allows for a completely metallic closure of the engine casing. This electrically continuous closure creates a Faraday cage, which is necessary for the proper functioning of the engine and to prevent electromagnetic interference.

[0014] According to one embodiment of the invention, the shielding piece is electrically conductive.

[0015] According to one embodiment of the invention, the shielding piece is assembled to the plastic housing by a fastening element formed from the plastic housing.

[0016] According to one embodiment of the invention, the shielding piece has an opening into which the fixing element is inserted.

[0017] According to one embodiment of the invention, the fastening element is thermally or mechanically deformable.

[0018] According to one embodiment of the invention, the fastening element is a stud allowing the assembly of the shielding piece to the plastic housing by studding.

[0019] According to one embodiment of the invention, the fastening element is a fir tree clip.

[0020] According to one embodiment of the invention, the opening is configured to pinch the fastening element.

[0021] According to one embodiment of the invention, the opening includes a flexible part which allows the insertion and pinching, by at least one side, of the fastening element.

[0022] The invention also relates to an electrical machine comprising a sensor according to the invention.

[0023] Other objects, features and advantages of the invention will be better understood and will become more apparent upon reading the description given below, with reference to the accompanying figures, given by way of example and in which:

[0024] - [Fig. 1] is a representation of an external view of a sensor according to a mode of the realization of the invention,

[0025] - [Fig. 2] is a representation of an internal view of a sensor according to a mode of realization of the invention,

[0026] - [Fig.3] is a schematic cross-sectional representation of the sensor according to a first embodiment of the invention, a) before riveting, b) after riveting,

[0027] - [Fig. 4] is a schematic cross-sectional representation of the sensor according to a second embodiment of the invention,

[0028] - [Fig. 5] is a schematic cross-sectional representation of the sensor according to a third embodiment of the invention,

[0029] - [Fig. 6] is a schematic top-view representation of the sensor according to a third embodiment of the invention,

[0030] - [Fig. 7] is a schematic top-view representation of the sensor according to a embodiment of the third variant of the invention.

[0031] The invention relates to an inductive position sensor 1, as illustrated in [Fig.1] to [Fig.7],

[0032] The inductive position sensor 1, associated with a non-visible coupling element, is intended to be mounted in a rotating electrical machine such as an electric motor of an electric or hybrid vehicle comprising a rotor rotating relative to a stator. The angular position of the rotor is determined relative to the stator.

[0033] The sensor includes an electronic board 10 on which are arranged at least one transmitting antenna 11, at least one receiving element 12 and at least one signal processing unit 13 [Fig.2].

[0034] According to one embodiment of the invention, at least one receiving antenna 12 is arranged inside at least one transmitting antenna 11.

[0035] During sensor operation, at least one transmitting antenna 11 emits an oscillating magnetic field at a given frequency. A coupling element is positioned to modify this magnetic field. According to one embodiment of the invention, the coupling element is mounted on one end of a rotor shaft to modify the magnetic field emitted by the transmitting antenna 11. The modified magnetic field generates an electromotive force in the receiving element 12. This electromotive force is processed by the signal processing unit 13 to provide output signals enabling the measurement of the coupling element's position.

[0036] According to one embodiment of the invention, the electronic card 10 has openings 15 allowing connection to wires or metallic connection elements.

[0037] According to one embodiment of the invention, the electronic card 10 consists of two substrate layers.

[0038] In the context of the invention, the sensor 1 includes a shielding system 50 visible on the [Fig.1] and [Fig.3] to [Fig.7].

[0039] In the context of the invention, the shielding system 50 is formed by at least one shielding piece 51 assembled on the outer surface 31 of the plastic housing 30. More precisely, on the upper outer surface 31 of the plastic housing 30. The upper outer surface 31 is the one that is oriented opposite to the shaft to which the sensor is attached.

[0040] According to one embodiment of the invention, the shielding component 51 is electrically conductive. According to one embodiment of the invention, the shielding component 51 is an electrically conductive plate.

[0041] According to one embodiment of the invention, the shielding part 51 completely covers the upper outer surface 31 of the plastic housing 30.

[0042] According to one embodiment of the invention, the shielding part 51 completely covers the outer surface of the plastic housing 30.

[0043] Such a sensor allows for a completely metallic closure of the engine casing. This electrically continuous closure creates a Faraday cage, which is necessary for the proper functioning of the engine and to prevent electromagnetic interference.

[0044] According to one embodiment of the invention, the shielding system 50 is formed by a shielding piece 51 and at least one fixing element 52 of the shielding piece 51 to the housing 30 visible on [Fig.1] and [Fig.3] to [Fig.7].

[0045] In the context of the invention, the fastening element 52 is an outgrowth formed from the plastic housing 30. It is therefore the housing that contains the fastening element 52. The fastening element 52 is thus made of plastic.

[0046] The shielding part 51 has at least one opening 53 into which a fixing element 52 is inserted to allow the assembly of the part 51 onto the housing 30.

[0047] Such an assembly allows for a simpler and less expensive design of the shielding piece 50 and the plastic housing 30.

[0048] According to a first embodiment of the invention, the fastening element 52 is thermally deformable. According to one embodiment of this embodiment, the fastening element 52 is a riveting pin. The pin 52 is inserted into the opening 53 of the shielding part 51 [Fig. 3] a) and riveted [Fig. 3] b). The assembly of the shielding part 51 onto the housing 30 is thus achieved by riveting.

[0049] The stamping step is carried out by deforming and crushing the pin under the action of heat. The pin 52, thus permanently deformed, has a specific shape that prevents axial displacement of the shielding part 51. Indeed, the crushing of the pin 52 forms a lip on the surface of the shielding part 51 which keeps it pressed against the surface 31 of the housing and thus holds it in place.

[0050] This button-jointing assembly allows for a simpler and less expensive design of the shielding part 51 and the plastic housing 30 with a simplified-shaped fastening element 52.

[0051] According to a second embodiment of the invention, the fastening element 52 is mechanically deformable. That is to say, the fastening element 52 is a clip whose shape allows it to be forcefully inserted into the opening 53 and prevents its removal. In one embodiment of this variant, the pin 52 is a fir tree clip or fir tree rivet. The fir tree pin 52 is inserted into the opening 53 of the shielding part 51 [Fig. 4]. The assembly of the shielding part 51 onto the housing 30 is thus achieved by clipping.

[0052] The fir tree pin 52 inserted in the opening 53 can no longer come out, which keeps the shielding piece 51 pressed against the surface 31 of the housing and thus holds it in place.

[0053] This clip-on assembly allows for a simpler and less expensive design of the shielding piece 50 and the plastic housing 30 with a simplified shaped fixing element 52.

[0054] According to a third embodiment of the invention, illustrated in [Fig. 5] to [Fig. 7], the fastening element 52 is a pin 524 or a rod 524. The shielding piece 51, in this third embodiment, comprises at least one opening 53 configured to retain the shielding piece 51 by at least one side of the fastening element 52. For this purpose, the opening comprises a flexible portion 525 which allows the insertion of the fastening element 52 and its clamping on at least one side or edge. The pin 524 or the rod 524 is inserted into the opening 53 of the shielding part 51 [Fig.4] by deformation of the elastic part 525 which, when it tends to return to its initial shape, pinches the pin 524 or the rod 524 on at least one side. The assembly of the shielding part 51 onto the housing 30 is thus achieved by a pinching type retention.

[0055] According to one embodiment of this variant, not illustrated, the opening is U-shaped or any other shape allowing at least one flexible tab to hold part 51 with the fastening element by a pinch-type hold.

[0056] According to another embodiment of this variant, [Fig. 6], the shielding piece 51 has two U-shaped openings, each forming a flexible tab 525 for retaining the piece 51 with the fastener by means of a pinch-type hold on one side. In this embodiment, the housing comprises two fasteners 524. According to this embodiment, the openings are located on one edge of the shielding piece 51, and, for example, are each located on an opposite edge. The shielding piece 51 is thus held in place between the two clamped fasteners 524, each on one side, by a flexible tab 525.

[0057] According to another embodiment of this variant, the opening is H-shaped [Fig.7]. This H-shape allows for two flexible tabs that hold the fastening element 52 by pinching.

[0058] This pinch assembly allows for a simpler and less expensive design of the shielding piece 50 and the plastic housing 30 with a simplified shaped fastening element 52.

[0059] The invention also relates to an electrical machine comprising a sensor 1 as described above.

[0060] The scope of the present invention is not limited to the details given above and allows for embodiments in many other specific forms without departing from the field of application of the invention. Therefore, the present embodiments should be considered by way of illustration and may be modified without, however, departing from the scope defined by the claims.

Claims

Demands

1. Inductive position sensor (1) for rotating electrical machine comprising a plastic housing (30) in which is disposed a printed circuit board (10) having at least one emitting element (11) for emitting an oscillating magnetic field, and at least one receiving device (12) for detecting a modified magnetic field, characterized in that it comprises a shielding system (50) formed by at least one shielding piece (51) assembled on the outer surface (31) of the plastic housing (30) by at least one fastening element (52) formed from the plastic housing (30), the shielding piece (51) having at least one opening (53) into which the fastening element (52) is inserted.

2. Inductive position sensor (1) according to claim 1, wherein the shielding piece (51) is electrically conductive.

3. Inductive position sensor (1) according to claim 1 or 2, wherein the fixing element (52) is thermally or mechanically deformable.

4. Inductive position sensor (1) according to any one of claims 1 to 3, wherein the fastening element (52) is a riveting pin allowing the assembly of the shielding part (51) to the plastic housing (30) by riveting.

5. Inductive position sensor (1) according to any one of claims 1 to 3, wherein the fixing element (52) is a fir tree clip.

6. Inductive position sensor (1) according to any one of claims 1 to 3, wherein the opening (53) is configured to pinch the fastening element (52).

7. Inductive position sensor (1) according to claim 6, wherein the opening (53) has a flexible part (525) which allows the insertion and retention by pinching, by at least one side, of the fastening element (52).

8. An electrical machine comprising a sensor (1) according to any one of claims 1 to 7.

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