Improved inductive position sensor

Abstract

The present invention relates to an inductive position sensor (1) for a rotating electrical machine comprising a printed circuit board (12) housed in at least one enclosure (10, 100, 11, 19, 101, 102, 103, 104, 15), having on its main face (120) at least one emitting element for emitting an oscillating magnetic field towards a rotating target (2) to generate a modified oscillating magnetic field, and at least one receiving device for detecting the modified oscillating magnetic field, the sensor comprising fluid circulation means (16, 17, 18, 166, 165) for allowing the circulation of a fluid into the interior of a rotor shaft (22, X) of the electrical machine formed by at least one conduit (16, 17, 18), the printed circuit board (12) being arranged so that its main face (120) is in vis-à-vis the target (2). Figure 1.

Description

Title of the invention: Improved inductive position sensor

[0001] The present invention relates to the field of position sensors. And more particularly to an improved inductive position sensor comprising a fluid circulation system.

[0002] 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.

[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 a rotor shaft to modify a magnetic field transmitted by a transmitter. The target is centered with respect to a rotor axis of rotation. The target comprises several vanes that provide a repeating and periodic magnetic field pattern with respect to the rotor axis of rotation.

[0005] The position sensor is fixed relative to the stator, opposite the target and the rotor. The position sensor comprises a printed circuit board (PCB), oriented away from the target and the rotor, having at least one emitting element intended to emit an oscillating magnetic field towards the target, generating a modified oscillating magnetic field at a given frequency.

[0006] The printed circuit board includes a receiver 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. The sensor is enclosed by a cover located above the printed circuit board, which can be glued, soldered, screwed, or clipped to the housing of a motor.

[0007] The disadvantage of these prior art sensors stems from the fact that they are not suitable for allowing good lubrication of the electric motor and have limited measurement accuracy.

[0008] The present invention therefore aims to overcome one of the drawbacks of those of the prior art by proposing a position sensor comprising an improved lubrication system for the electric motor with better measurement accuracy.

[0009] To this end, the present invention proposes an inductive position sensor for a rotating electrical machine comprising a printed circuit board, housed in at least one casing, having on its main face at least one emitting element for emitting an oscillating magnetic field towards a rotating target to generate a modified oscillating magnetic field, and at least one receiving device for detecting the modified oscillating magnetic field, the sensor comprising means for fluid circulation to allow the circulation of a fluid into the interior of a rotor shaft of the electrical machine formed by at least one conduit, the printed circuit board being arranged so that its main face is opposite the target.

[0010] According to one embodiment of the invention, the printed circuit board is housed in at least one case and supported by a base of the case.

[0011] According to one embodiment of the invention, the case has an opening, the bottom being the face opposite this opening.

[0012] According to one embodiment of the invention, the bottom of the housing is arranged in a plane perpendicular to the longitudinal axis of the shaft.

[0013] According to one embodiment of the invention, the opening is oriented towards one end of the shaft.

[0014] According to one embodiment of the invention, the housing is closed by a cover fixed, for example, by laser welding.

[0015] According to one embodiment of the invention, the fluid circulation means comprise a first conduit opening into a cavity formed on the outer face of the bottom of the housing, oriented opposite the printed circuit board, the cavity being configured to open into a third conduit formed by the motor shaft.

[0016] According to one embodiment of the invention, the fluid circulation cavity is closed by a second cover fixed, for example, by laser welding.

[0017] The invention also relates to an electrical machine comprising a sensor according to the invention.

[0018] The invention also relates to a mobility device, for example a motor vehicle, comprising an electric machine according to the invention.

[0019] 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:

[0020] - Fig. 1 is a representation of a longitudinal cross-sectional view of the sensor and of the drive shaft according to one embodiment of the invention,

[0021] - [Fig. 2] is a representation of a bottom view of the sensor according to a mode of realization of the invention with the target,

[0022] - [Fig. 3] is a representation of a bottom view of the sensor showing the card printed circuit board of the sensor according to an embodiment of the invention,

[0023] - [Fig. 4] is a representation of a top view of the sensor without the cover of the sensor according to an embodiment of the invention,

[0024] - [Fig. 5] is a representation of a bottom view of the sensor showing the sensor cover according to one embodiment of the invention,

[0025] - [Fig. 6] is a representation of a top view of the sensor showing the second cover of the sensor according to an embodiment of the invention.

[0026] The invention relates to an inductive position sensor 1, as illustrated in [Fig. 1] to [Fig. 6] incorporating means for circulating the lubricating fluid of an electrical machine.

[0027] The inductive position sensor 1 uses a magnetic field to determine the angular position of a visible rotating target 2 [Fig.2] which is used as a coupling element.

[0028] The inductive position sensor 1 and the target 2 are intended to be mounted in a rotating electrical machine, not shown, 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.

[0029] According to one embodiment of the invention, the sensor 1 is fixed to the cover of the electric machine by a screw-type fixing system 19.

[0030] The target 2 is mounted on one end of a shaft 22 of the rotor to modify a magnetic field emitted by a transmitter.

[0031] According to one embodiment of the invention, the target 2 comprises a rotation axis X which is aligned with a rotation axis of the rotor. According to one embodiment of the invention, the target 2 comprises at least two angular sectors 21, and for example 3, 4, 5 or 6 which provide a repeating and periodic magnetic field pattern with respect to the rotation axis of the rotor.

[0032] According to one embodiment of the invention, the sensor 1 is positioned opposite the target 2 at the end of the rotor shaft 22. More specifically, the position sensor 1 is fixed relative to the stator, opposite the target 2 at the end of the rotor shaft 22. Therefore, in order of positioning on the shaft, there is the rotor / stator, then the target 2, then the position sensor 1. These elements are arranged coaxially with the X-axis of the rotor shaft.

[0033] According to one embodiment of the invention, the sensor 1 is through-hole, i.e. the rotor shaft 22 passes through the center of the sensor, not illustrated

[0034] According to one embodiment of the invention, the sensor 1 is non-through, that is to say, it is disposed at the end of the shaft 22 of the rotor.

[0035] The inductive position sensor 1 [Fig.3] includes at least one printed circuit board 12, referred to as a PCB (Printed Circuit Board), having on its main face 120 at least one emission element 13 intended to emit an oscillating magnetic field towards the target 2, which returns a modified oscillating magnetic field at a given frequency.

[0036] This printed circuit board 12 includes on its main face 120 a receiving device 14 intended to detect the modified oscillating magnetic field and to transmit to a signal processing unit 6 to measure the angular position of target 2. The modified oscillating magnetic field generates an electromotive force at a given frequency in the receiving device 14. This electromotive force is processed by the signal processing unit 6 so as to provide output signals enabling the measurement of the position of target 2.

[0037] The inductive position sensor 1 is fixed relative to the stator. The printed circuit board is positioned opposite the target 2.

[0038] According to one embodiment of the invention, the printed circuit board 12 is housed in at least one housing 10 and supported by the bottom 101 of the housing 10. This housing forms the body 10 of the sensor 1. The printed circuit board 12 is arranged in a housing 100 of the housing so that its main face 120 is opposite the target.

[0039] According to one embodiment of the invention, the case has an opening 102, the bottom 101 is the face opposite this opening 102.

[0040] According to one embodiment of the invention, the bottom 101 of the housing 10 is arranged in a plane P perpendicular to the axis X of the shaft 22.

[0041] In the context of the invention, the opening 102 is oriented towards the end 221 of the shaft 22. The base 101 is therefore arranged so that the transmitting elements 13 and receiving elements 14 are oriented towards the target. This allows the transmitting elements 13 and receiving elements 14 to be positioned opposite the target. This arrangement reduces the distance between the target and the receiving element 14, thereby improving signal strength and measurement accuracy.

[0042] According to one embodiment of the invention, the housing 10 is closed by a cover or hood 11. The cover 11 is disposed between the printed circuit board 12 and the target 2 and closes the opening 102 of the housing.

[0043] According to one embodiment of the invention, the cover 11 is fixed by laser welding or by any other compatible fixing technology.

[0044] The sensor 1 according to the invention is configured to allow the circulation of a fluid up to the inside of the shaft 22 of the rotor.

[0045] For this purpose, the sensor 1 includes means for circulating a fluid.

[0046] According to one embodiment of the invention, the means are formed by at least one first fluid inlet conduit 16. This conduit 16 is configured to be in communication with a fluid reservoir of the machine.

[0047] According to one embodiment of the invention, this first conduit 16 is formed in the body 10 of the sensor 1.

[0048] According to one embodiment of the invention, the first conduit 16 is arranged coaxially to the X axis of the shaft 22 and perpendicularly to the card 12 of the printed circuit of the sensor 1.

[0049] According to one embodiment of the invention [Fig.1], the first conduit 16 is opened by a first end 165 which is configured to be positioned at the level of a fluid reservoir, so as to receive the fluid from the reservoir by gravity oil flow or pressurized fluid.

[0050] According to one embodiment of the invention, the first conduit 16 extends to a fluid circulation cavity 17. The second end 166 of the first conduit 16 opens into this fluid circulation cavity 17.

[0051] According to one embodiment of the invention [Fig.4], the fluid circulation cavity 17 is formed at the bottom 101 of the sensor housing 1. More specifically, the fluid circulation cavity 17 is formed on the outer face 103 of the bottom 101 of the housing, oriented opposite to the printed circuit board 12 of the sensor 1. The inner face 104 of the housing is the one on which the printed circuit board 12 rests.

[0052] According to one embodiment of the invention, the fluid circulation cavity 17 is formed by a second conduit 17.

[0053] According to one embodiment of the invention, the second conduit 17 is overmolded or molded with the housing 10.

[0054] According to one embodiment of the invention, the second conduit 17 is arranged to form an angle between 70 and 110 degrees with the X axis of the motor 22.

[0055] According to one embodiment of the invention, the second conduit 17 is arranged perpendicular to the X axis of the motor 22 and therefore perpendicular to the first conduit 16.

[0056] According to one embodiment of the invention, the second conduit 17 is a conduit open along at least part of its length, in the form of a groove. That is to say, it forms a U, or any other equivalent shape, in which the fluid flows.

[0057] According to one embodiment of the invention, the longitudinal opening of the conduit is oriented towards the outside of the sensor 1.

[0058] According to one embodiment of the invention, the second conduit 17 is configured to open into the inside of the shaft 22 of the motor which thus forms a third conduit 18.

[0059] According to one embodiment of the invention, the interior of the motor shaft 22, forming a third conduit 18, has openings (not shown) that allow the fluid to be distributed within the electric machine through the center of the rotor shaft's X-axis by centrifugal force, which propels the fluid against the shaft walls. This configuration thus prevents the fluid from being dispersed directly at the reservoir outlet. With this configuration, the fluid is brought to the center of the rotor shaft and then dispersed through the rotor's interior, resulting in improved lubrication.

[0060] In the context of the invention, the fluid circulation cavity 17 is closed by a second cover or hood 15 [Fig. 1] and [Fig. 6]. This cover 15 is thus arranged way of closing the fluid circulation cavity 17 at the level of the outer face 103 of the housing 10 of the sensor 1.

[0061] According to one embodiment of the invention, the second cover 15 is fixed by laser welding or any other compatible fixing method.

[0062] According to one embodiment of the invention, the fluid is oil, and more specifically lubricating oil. The circulation of the oil via the shaft allows the lubrication of the electrical machine, and for example of the gears of the electrical machine.

[0063] Thus such a sensor according to the invention allows the lubrication of the elements of the electrical machine without additional system.

[0064] According to an embodiment of the invention [Fig.2], [Fig.4], [Fig.5], [Fig.6], the sensor comprises a connection element 20 connected to connection elements, themselves connected to the printed circuit board 12. The connection element allows a connection with another external element, for example of the vehicle, to transmit the output signal of the sensor 1.

[0065] The invention also relates to an electric machine comprising a sensor 1 as described above, as well as a mobility device comprising an electric machine equipped with a sensor according to the invention.

[0066] 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 printed circuit board (12), housed in at least one housing (10), having on its main face (120) at least one emitting element (13) for emitting an oscillating magnetic field towards a rotating target (2) to generate a modified oscillating magnetic field, and at least one receiving device (14) for detecting the modified oscillating magnetic field, the sensor comprising fluid circulation means (16, 17, 18) for allowing the circulation of a fluid into the interior of a rotor shaft (22) of the electrical machine formed by at least one conduit (16, 17, 18), characterized in that the printed circuit board (12) is arranged so that its main face (120) is opposite the target (2).

2. Inductive position sensor (1) according to claim 1, wherein the printed circuit board (12) is housed in at least one housing (10) and supported by a bottom (101) of the housing (10).

3. Inductive position sensor (1) according to claim 2, the housing has an opening (102), the bottom (101) being the face opposite this opening (102).

4. Inductive position sensor (1) according to claim 2 or 3, wherein the bottom (101) of the housing (10) is disposed in a plane (P) perpendicular to the longitudinal axis (X) of the shaft (22).

5. Inductive position sensor (1) according to claim 3 or 4, wherein the opening (102) is oriented towards one end (221) of the shaft (22).

6. Inductive position sensor (1) according to any one of claims 2 to 5, wherein the housing (10) is closed by a cover (11) fixed, for example, by laser welding.

7. Inductive position sensor (1) according to any one of claims 1 to 6, wherein the fluid circulation means (16, 17, 18) comprise a first conduit (16) opening into a cavity (17) formed on the outer face (103) of the bottom (101) of the housing, oriented opposite the printed circuit board (12), the cavity (17) being configured to open into a third conduit (18) formed by the shaft (22) of the motor.

8.

9.

10. Inductive position sensor (1) according to claim 7, in which the fluid circulation cavity (17) is closed by a second cover (15) fixed, for example, by laser welding. Electric machine (3) comprising a sensor (1) according to any one of claims 1 to 8. Mobility device, for example a motor vehicle, comprising an electric machine according to claim 9.

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