Inductive position sensor with two printed circuits

Abstract

The invention relates to an inductive position sensor (1) for a rotary electric machine, the sensor comprising a first substrate (2a) that comprises at least one emitting element configured to emit an oscillating magnetic field towards a rotating target in order to generate a modified oscillating magnetic field, and a receiving device configured to detect the modified oscillating magnetic field and transmit it to a signal processing unit in order to determine the angular position of the target. The signal processing unit is positioned on a second substrate (2b) at a distance from the first substrate (2a) and is connected to the first substrate (2a) by connecting means (4) that are configured to transmit the modified oscillating magnetic field to the signal processing unit.

Description

[0001] DESCRIPTION

[0002] TITLE OF THE INVENTION: Inductive position sensor with two printed circuits

[0003] The invention relates to the field of position sensors. It relates more particularly to the field of position sensors which are configured to detect the angular position of a rotating target inductively.

[0004] Inductive position sensors, known as eddy current sensors, use a magnetic field to determine the angular position of the rotating target which forms a coupling element.

[0005] These position sensors are used in particular in electric motors of electric or hybrid vehicles comprising a rotor rotating relative to a stator.

[0006] The angular position of the rotor is determined relative to the stator. The target is mounted on the end of a rotor shaft to modify a magnetic field transmitted by a transmitter. The target is centered relative to an axis of rotation of the rotor. The target comprises several blades that provide a repeating and periodic pattern relative to the rotor axis of rotation.

[0007] The position sensor is mounted fixed relative to the stator, opposite the target and the end of the rotor shaft. The position sensor comprises a printed circuit called PCB (Printed Circuit Board) comprising at least one transmission element intended to transmit an oscillating magnetic field towards the target, generating a modified oscillating magnetic field at a given frequency.

[0008] A printed circuit board is a base plate (substrate) that physically and wires surface-mounted components called CMS (Surface Mounted Components).

[0009] The printed circuit includes a receiving device for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit provided on the printed circuit to deduce the angular position of the target.

[0010] The transmitting element has a circular shape and is centered around a transmitting axis. The receiving device also has a circular shape and is centered around a receiving axis. The receiving device is concentric with the transmitting element.

[0011] The emission axis of the emission element and the reception axis of the reception device are merged with the rotation axis of the target which is itself merged with the rotation axis of the rotor.

[0012] Conventionally, the signal processing unit is integrated on the printed circuit and positioned outside the transmitting device and the receiving element, on the periphery of the latter.

[0013] However, these inductive position sensors are bulky and therefore more difficult to integrate into rotating electrical machines.

[0014] Document FR2214742 proposes placing the signal processing unit inside the transmission device and the reception element so as to obtain a reduced-size electronic card.

[0015] However, in some mounting cases, the space available inside the transmitting device and the receiving element is not sufficient to accommodate the signal processing unit in its entirety.

[0016] This is even more problematic when the position sensor comprises several signal processing units because it is necessary to increase the diameter of the transmitting device and the receiving element, resulting in a bulky position sensor and therefore difficult to integrate into an electrical machine system, for example.

[0017] The aim of the invention is therefore to overcome the drawbacks of the prior art by proposing an inductive position sensor that is more compact and easier to integrate into a rotating electrical machine.

[0018] To this end, the invention thus relates, in its broadest sense, to an inductive position sensor for a rotating electrical machine comprising a first substrate comprising at least one transmitting element intended to transmit an oscillating magnetic field towards a rotating target to generate a modified oscillating magnetic field. The first substrate also comprises a receiving device intended to detect the modified oscillating magnetic field and to transmit it to a signal processing unit to determine the angular position of the target.

[0019] According to the invention, the signal processing unit is positioned on a second substrate, distant from the first substrate, and connected to the first substrate by electrical connection means configured to transmit an electrical signal image of the modified oscillating magnetic field to the signal processing unit.

[0020] The invention makes it possible to reduce the size of the electronic card comprising the transmitting element and the receiving device and thus to provide a more compact inductive position sensor that is easier to integrate into a rotating electrical machine.

[0021] The invention also makes it possible to increase the size of the transmitting and / or receiving antennas without increasing the size of the inductive position sensor.

[0022] According to a variant, the second substrate is offset relative to the first substrate along a central axis perpendicular to the first substrate.

[0023] This solution allows to reduce the width of the inductive position sensor.

[0024] According to a variant, the second substrate is offset relative to the first substrate and oriented perpendicular to the latter, parallel to a central axis.

[0025] According to one embodiment, the inductive position sensor comprises a housing in which the first and second substrates are housed. The first substrate is positioned on a base of the housing and the second substrate is positioned on a support of the housing. The support is offset from the base along the central axis.

[0026] This arrangement provides a simple solution to reduce the width of the inductive position sensor without the need to modify the structure of existing inductive position sensors.

[0027] According to one variant, the base and the support are connected by a wall. The connecting means run along the wall.

[0028] This allows the length of the connecting means to be reduced.

[0029] According to one variant, the support is positioned opposite a connector located outside the housing.

[0030] This reduces the electrical connections between the connector and the second substrate.

[0031] According to one variant, the connecting means comprise several metal wires. According to one variant, the connecting means comprise a flexible electrical cable sheet.

[0032] According to one variant, the connecting means comprise a third flexible substrate comprising electrical connecting elements.

[0033] According to one embodiment, the second substrate and the third flexible substrate form a single flexible substrate.

[0034] This helps simplify the manufacturing process.

[0035] The invention also relates to a rotating vehicle electrical machine comprising a stator and a rotor mounted for rotation relative to the stator.

[0036] The rotating electrical machine comprises an inductive position sensor as defined previously and a target positioned on the rotor, opposite the inductive position sensor.

[0037] Embodiments of the present invention will be described below, by way of non-limiting examples, with reference to the appended figures in which:

[0038] [Fig.1] schematically illustrates an inductive position sensor;

[0039] [Fig.2] schematically illustrates a view, along an axial section, of the inductive position sensor;

[0040] [Fig.3] schematically illustrates a first substrate and a second substrate of the inductive position sensor.

[0041] The invention relates to an inductive position sensor 1, as illustrated in Figures 1 to 3.

[0042] The inductive position sensor 1 uses a magnetic field to determine the angular position of a rotating target which is used as a coupling element.

[0043] The inductive position sensor 1 and the target are 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.

[0044] The angular position of the rotor is determined relative to the stator. The target is mounted on one end of a rotor shaft to modify a magnetic field emitted by a transmitter. The target includes an axis of rotation that coincides with an axis of rotation of the rotor. The target includes several blades that provide a repeating and periodic pattern relative to the axis of rotation of the rotor.

[0045] The inductive position sensor 1 comprises a first substrate 2a (or printed circuit called PCB) comprising one or more emission elements 3a, 3b, 3c intended to emit an oscillating magnetic field, the target generating a modified oscillating magnetic field at a given frequency.

[0046] The first substrate 2a comprises a receiving device 5 for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit 6 for measuring the angular position of the target. The modified oscillating magnetic field generates an electromotive force in the receiving device 5. This electromotive force is processed by the signal processing unit 6 so as to provide output signals for measuring the position of the target.

[0047] The inductive position sensor 1 is mounted fixed relative to the stator. The transmitting elements 3a, 3b, 3c and the receiving device 5 of the inductive position sensor 1 are positioned opposite the target and therefore opposite the end of the rotor shaft. The center of the transmitting elements 3a, 3b, 3c and of the receiving device 5 is crossed by a central axis A also crossing the center of the axis of rotation of the rotor. The central axis A is perpendicular to the first substrate 2a.

[0048] The receiving device 5 comprises several windings and has a generally circular section and more precisely an annular shape.

[0049] Traditionally, the number of windings of the receiving device 5 is proportional to the number of blades (or angular sectors) of the target.

[0050] At least one emission element 3a, 3b, 3c has a symmetry of revolution. Preferably, at least one emission element 3a, 3b, 3c has a circular shape, and are centered around a common emission axis.

[0051] According to one variant, the three emission elements 3a, 3b, 3c have a symmetry of revolution. Preferably, the three emission elements 3a, 3b, 3c have a circular shape, and are centered around a common emission axis. Alternatively, the inductive position sensor 1 may comprise a single emission element 3a, 3b, 3c or two emission elements 3a, 3b, 3c or more than three emission elements 3a, 3b, 3c.

[0052] The first substrate 2a, the emission elements 3a, 3b, 3c and the reception device 5 form a first electronic card which is housed in a housing 8 and supported by a base 10 of the housing 8.

[0053] According to the invention, the signal processing unit 6 is positioned on a second substrate 2b or printed circuit called PCB ("Printed Circuit Board" in English), distant from the first substrate 2a, and connected to the first substrate 2a by connecting means 4.

[0054] The first and second substrates 2a, 2b are housed in the housing 8.

[0055] The second substrate 2b is offset relative to the first substrate 2a along the vertical axis A. In other words, the second substrate 2b is not at the same level or at the same height as the first substrate 2a.

[0056] The second substrate 2b is positioned on a support 11 of the housing 8. The support 11 is offset relative to the base 10 along the central axis A, forming a step with the base 10.

[0057] The base 10 and the support 11 extend in a direction substantially perpendicular to the central axis A and are connected by a wall 12 which is substantially parallel to the central axis A. The connecting means 4 run along the wall 12. The connecting means 4 may be in contact with the wall 12 or fixed to the wall 12.

[0058] The connecting means 4 are configured so that the electromotive force generated in the receiving device 5 by the oscillating magnetic field passes through the connecting means 4 to the signal processing unit 6.

[0059] The connecting means 4 comprise several metal wires.

[0060] Alternatively, the connecting means 4 comprise a flexible electrical cable sheet.

[0061] Alternatively, the connecting means 4 comprise a third flexible substrate (flexible PCB) comprising electrical connecting elements.

[0062] The first and second substrates 2a, 2b are substantially rigid and connected to the third flexible substrate. Alternatively, the second substrate 2b and the third flexible substrate form a single flexible substrate.

[0063] Alternatively, a first portion of the single flexible substrate comprises the signal processing unit 6 and is fixed to the support 11.

[0064] A second portion of the single flexible substrate comprises electrical connections and is connected to the first portion of the single flexible substrate. The second portion runs along the wall 12 of the housing 8.

[0065] The support 11 is positioned opposite a connector 13 located outside the housing 8.

[0066] The housing 8 comprises a cover 15 closing over the cavity in which the substrates 2a, 2b are housed.

[0067] As illustrated in Figure 3, the second substrate 2b comprises several orifices 7 and electrical connections 9 connecting the signal processing unit 6 to connection elements 14 of the connector 13. The connection elements 14 extend from the connector 13 to the orifices 7.

[0068] The electrical connections 9 may be electrical wires or metal tracks etched on the second substrate layer, for example.

[0069] Alternatively, the second substrate 2b can be positioned on a vertical wall such as the wall 12 of the housing 8 or another wall of the housing 8.

[0070] Alternatively, the second substrate 2b may comprise two signal processing units 6 positioned next to each other.

[0071] Alternatively, the second substrate 2b may comprise two signal processing units 6 positioned on two different second substrates 2b positioned next to each other or positioned at different locations in the housing 8.

[0072] The second substrates 2b are connected to the first substrate 2a by two separate connecting means.

Claims

CLAIMS 1. Inductive position sensor (1) for a rotating electrical machine comprising a first substrate (2a) comprising at least one transmitting element (3a, 3b, 3c) intended to transmit an oscillating magnetic field towards a rotating target to generate a modified oscillating magnetic field and a receiving device (5) intended to detect the modified oscillating magnetic field and to transmit it to a signal processing unit (6) to determine the angular position of the target, characterized in that the signal processing unit (6) is positioned on a second substrate (2b), distant from the first substrate (2a), and connected to the first substrate (2a) by connecting means (4) configured to transmit an electrical signal image of the modified oscillating magnetic field to the signal processing unit (6).

2. Inductive position sensor (1) according to claim 1, characterized in that the second substrate (2b) is offset relative to the first substrate (2a) along a central axis (A) perpendicular to the first substrate (2a).

3. Inductive position sensor (1) according to claim 1, characterized in that the second substrate (2b) is offset relative to the first substrate (2a) and oriented perpendicular to the latter, parallel to a central axis (A).

4. Inductive position sensor (1) according to claim 2 or 3, characterized in that it comprises a housing (8) in which the first and second substrates (2a, 2b) are housed, the first substrate (2a) being positioned on a base (10) of the housing (8) and the second substrate (2b) being positioned on a support (11) of the housing (8), the support (11) being offset relative to the base (10) along the central axis (A).

5. Inductive position sensor (1) according to claim 4, characterized in that the base (10) and the support (11) are connected by a wall (12), the connecting means (4) running along the wall (12).

6. Inductive position sensor (1) according to any one of claims 4 or 5, characterized in that the support (11) is positioned opposite a connector (13) located outside the housing (8).

7. Inductive position sensor (1) according to any one of claims 1 to 6, characterized in that the connecting means (4) comprise several metal wires.

8. Inductive position sensor (1) according to any one of claims 1 to 6, characterized in that the connecting means (4) comprise a flexible electrical cable strip.

9. Inductive position sensor (1) according to any one of claims 1 to 6, characterized in that the connecting means (4) comprise a third flexible substrate comprising electrical connecting elements.

10. Inductive position sensor (1) according to claim 9, characterized in that the second substrate (2b) and the third flexible substrate form a single flexible substrate.

11. Rotating electrical machine for a vehicle comprising a stator and a rotor mounted to rotate relative to the stator, characterized in that it comprises an inductive position sensor (1) as defined according to any one of claims 1 to 10, and a target positioned on the rotor, opposite the inductive position sensor (1).

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