Inductive position sensor integrated into a motor housing

Abstract

The present invention relates to an inductive position sensor (1) for a rotating electric machine comprising a printed circuit board (10) on which at least one transmitting element (11) is arranged, the transmitting element being intended to transmit an oscillating magnetic field towards a rotating target in order to generate a modified magnetic field, and at least one receiving device (12) intended to detect the modified magnetic field, characterised in that it is configured to form at least one portion of the housing (14) of an electric machine.

Description

[0001] Description

[0002] Title of the invention: INDUCTIVE POSITION SENSOR INTEGRATED IN AN ENGINE HOOD

[0003] The present invention relates to the field of position sensors. And more particularly to an inductive position sensor integrated into an electric motor cover. Inductive position sensors, known as eddy current sensors, use an oscillating magnetic field to determine the angular position of the rotating target which forms a coupling element.

[0004] These position sensors are used in particular in electric motors of electric or hybrid vehicles comprising a rotor rotating relative to a stator.

[0005] 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 an oscillating 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 magnetic field pattern relative to the rotor rotation axis.

[0006] The position sensor is mounted fixed relative to the stator, opposite the target and the end of the rotor. The position sensor comprises a printed circuit board (PCB) 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.

[0007] The printed circuit board comprises 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. The sensor is closed by a cover.

[0008] Usually the position sensor is positioned and held in position using screws on a metal engine cover.

[0009] The disadvantage of such an assembly is that it requires the use of several screws, plastic housings and metal parts assembled together, which generates additional costs. In addition, the assembly of multiple parts causes centering inaccuracies and degrades the performance of the position sensor.

[0010] The present invention therefore aims to overcome one of the drawbacks of those of the prior art by proposing a position sensor integrated into an electric motor cover. For this purpose, the present invention proposes an inductive position sensor for a rotating electrical machine comprising a printed circuit board on which are arranged at least one transmitting element intended to transmit an oscillating magnetic field towards a rotating target to generate a modified magnetic field, and at least one receiving device intended to detect the modified magnetic field, the sensor being configured to form at least part of the cover of an electric machine.

[0011] According to one embodiment of the invention, the position sensor is integrated into an electrical machine cover, and forms a single piece with the cover.

[0012] In this way, assembly is optimized, assembly tolerances are reduced and overall cost is reduced.

[0013] According to one embodiment of the invention, the inductive position sensor comprises a housing for arranging the printed circuit board of the sensor.

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

[0015] According to one embodiment of the invention, the sensor is configured to allow the circulation of a fluid to the interior of the electrical machine.

[0016] According to one embodiment of the invention, the sensor comprises an opening to allow the passage of a fluid.

[0017] According to one embodiment of the invention, the opening is extended by a conduit configured to open into a shaft of the electric machine.

[0018] According to one embodiment of the invention, the sensor comprises a seal arranged on the contour of the cover on the lower face of the cover.

[0019] According to one embodiment of the invention, the sensor comprises a fluid inlet at the opening formed by a metal or plastic part assembled on the cover on the upper face of the cover.

[0020] The invention also relates to an electrical machine comprising a sensor according to the invention. Other aims, characteristics and advantages of the invention will be better understood and will appear more clearly on reading the description given below, with reference to the appended figures, given by way of example and in which:

[0021] - [Fig. 1] is a representation of the electronic card of the sensor according to the invention,

[0022] - [Fig. 2] is an elevation view of the sensor according to the invention, seen from below,

[0023] - [Fig. 3] is an elevation view of the sensor according to the invention, seen from below with a closing plate,

[0024] - [Fig. 4] is an elevation view of the sensor according to the invention, seen from above.

[0025] The invention relates to an inductive position sensor 1, as illustrated in [Fig.l] to [Fig.4] integrated in a motor cover of an electric machine.

[0026] The inductive position sensor 1 uses a magnetic field to determine the angular position of a rotating target (not shown) which is used as a coupling element.

[0027] 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. 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.

[0028] According to one embodiment of the invention, the target comprises an axis of rotation that is aligned with an axis of rotation of the rotor. The target comprises a plurality of blades that provide a repetitive and periodic magnetic field pattern relative to the axis of rotation of the rotor.

[0029] According to one embodiment of the invention, the sensor 1 is arranged opposite the target and the rotor. There is therefore, in order of positioning on the shaft, the rotor / stator then the target, then the position sensor. The target and the sensor are arranged parallel to each other and perpendicular to the axis of the rotor shaft.

[0030] According to one embodiment of the invention, the sensor 1 is through-sensor, that is to say that the rotor shaft passes through the center of the sensor.

[0031] According to one embodiment of the invention, the sensor 1 is non-through, that is to say it is arranged at the end of the rotor shaft.

[0032] The inductive position sensor 1 comprises at least one printed circuit board 10 called PCB (Printed Circuit Board in English) comprising at least one emission element 11 intended to emit an oscillating magnetic field towards the target, which returns a modified oscillating magnetic field at a given frequency.

[0033] This printed circuit board 10 comprises a receiving device 12 for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit 13 for measuring the angular position of the target. The modified oscillating magnetic field generates an electromotive force at a given frequency in the receiving device 12. This electromotive force is processed by the signal processing unit 13 so as to provide output signals for measuring the position of the target.

[0034] The inductive position sensor 1 is mounted fixed relative to the stator. The transmitting element 11 and the receiving device 12 of the inductive position sensor 1 are positioned opposite the target.

[0035] According to one embodiment of the invention, the receiving device 12 comprises several windings and has a circular section and more precisely an annular shape.

[0036] According to one embodiment of the invention, the number of windings of the receiving device 12 is proportional to the number of blades (or angular sectors) of the target.

[0037] According to one embodiment of the invention, the target comprises at least two angular sectors 21, and for example 3, 4, 5 or 6.

[0038] The printed circuit board 10, the transmitting elements 11 and the receiving device 12 are housed in at least one housing 16 and supported by a base of the housing. This housing forms the body 16 of the sensor 1.

[0039] According to one embodiment of the invention, the signal processing unit 13 is positioned on the same substrate as the transmission and reception elements or on another substrate, housed in the housing 16.

[0040] In the context of the invention, the sensor is configured to form at least a portion of the cover 14 of the electric motor. That is to say, the sensor 1 is integrated into the cover 14 of the electric motor. The cover 14 of the motor and the housing 16 of the sensor are formed in a single piece.

[0041] In this way, the assembly is optimized, the assembly tolerances are reduced and the overall cost is reduced. According to one embodiment of the invention, the cover 14 is made of shielding material, for example plastic with ferromagnetic particles or steel. This makes it possible to limit the propagation of the field emitted by the sensor.

[0042] According to one embodiment of the invention, the cover 14 is made of plastic.

[0043] The sensor thus has the shape of a standard electric motor cover 14, in which the housing 16 of the sensor is provided to accommodate the printed circuit board 10 of the sensor 1.

[0044] According to one embodiment of the invention, the housing 16 is arranged so that the transmitting 11 and receiving 12 elements are opposite the target. According to one embodiment of the invention, the housing 16 is substantially in the center of the cover 14, and for example is in the center of the cover 14.

[0045] According to one embodiment of the invention, the housing 16 comprises an opening located on the lower or upper face of the cover 14. The lower face being the one facing the electrical machine. The outer face being defined relative to the lower face which is facing the electrical machine.

[0046] According to one embodiment of the invention, the housing 16 forms a protrusion 167 on the face of the cover 14, opposite that of its opening.

[0047] According to one embodiment of the invention, the housing 16 is closed by a cover 17.

[0048] According to one embodiment of the invention, the cover 17 is made of plastic.

[0049] According to one embodiment of the invention, the cover 14 comprises a seal 161 arranged on the contour of the cover to provide a sealed engine housing. The seal 161 is arranged on the lower face of the cover 14. According to one embodiment of the invention, the seal 161 is made of a flexible plastic material, of the elastomer type.

[0050] According to one embodiment of the invention, the cover 14 comprises on its outer face a connection system 162, which allows the connection of the printed circuit 10 with the exterior. According to one embodiment of the invention, the cover 14 comprises an opening 163 to allow the passage of a fluid.

[0051] According to one embodiment of the invention, the fluid is lubricating oil for the electrical machine.

[0052] According to one embodiment of the invention, the opening 163 is extended by a conduit 164.

[0053] According to one embodiment of the invention, the conduit 164 passes through the housing 16 and the printed circuit board 10. The conduit 164 is thus arranged on the same face as the housing 16. According to one embodiment of the invention, the conduit 164 is configured to open into the rotor shaft. The rotor shaft thus comprises openings allowing the circulating fluid to be distributed in the electrical machine thanks to the centrifugal force which propels the fluid against the walls of the shaft.

[0054] According to one embodiment of the invention, the conduit 164 is an extension of the cover 14 or an additional part, for example overmolded with the cover.

[0055] According to one embodiment of the invention, the conduit 164 is arranged along the longitudinal axis of the rotor.

[0056] According to one embodiment of the invention, the arrival of the fluid at the opening 163 is formed by a part 166 made of metal or plastic assembled on the hose-type cover. This part 166 is arranged on the face of the cover opposite that where the housing is located. This part allows the arrival of the fluid which will then circulate in the fluid conduit to the shaft of the electric machine.

[0057] According to one embodiment of the invention, the cover 14 comprises at least two openings 165 on its periphery allowing it to be fixed to the casing of the electrical machine. The openings 165 allow fixing, for example, by screwing screws through the openings.

[0058] Sensor 1 is thus configured to allow the circulation of a fluid to the interior of the rotor shaft.

[0059] The passage of the conduit 164 in the center of the sensor allows 1 to have a totally cylindrical antenna 11, 12, which makes it possible to maintain good signal precision.

[0060] The invention also relates to an electrical machine comprising a sensor 1 as described previously.

[0061] The scope of the present invention is not limited to the details given above and allows embodiments in many other specific forms without departing from the scope of the invention. Therefore, the present embodiments should be considered by way of illustration, and may be modified without departing from the scope defined by the claims.

Claims

CLAIMS 1. Inductive position sensor (1) for a rotating electrical machine comprising a printed circuit board (10) on which are arranged at least one transmitting element (11) intended to transmit an oscillating magnetic field towards a rotating target to generate a modified magnetic field, and at least one receiving device (12) intended to detect the modified magnetic field, characterized in that it is configured to form at least a part of the cover (14) of an electrical machine.

2. Inductive position sensor (1) according to claim 1, integrated in a cover (14) of an electric machine.

3. Inductive position sensor (1) according to claim 1 or 2, comprising a housing (16) for arranging the printed circuit board (10) of the sensor.

4. Inductive position sensor (1) according to one of claims 1 to 3, wherein the housing (16) is closed by a cover (17), for example made of plastic.

5. Inductive position sensor (1) according to one of claims 1 to 4, configured to allow the circulation of a fluid to the interior of the electrical machine.

6. Inductive position sensor (1) according to one of claims 1 to 5, comprising an opening (163) to allow the passage of a fluid.

7. Inductive position sensor (1) according to claim 6, wherein the opening (163) extends into a conduit (164) configured to open into a shaft of the electrical machine.

8. Inductive position sensor (1) according to one of claims 1 to 7, comprising a sealing gasket (161) arranged on the contour of the cover (14) arranged on the lower face of the cover 14.

9. Inductive position sensor (1) according to one of claims 1 to 8, comprising an inlet (166) of the fluid at the opening (163) formed by a metal or plastic part assembled on the cover (14) on the upper face of the cover 14.

10. Electrical machine comprising a sensor (1) according to one of claims 1 to 9.

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