Inductive position sensor with improved fluid circulation system

Abstract

The present invention relates to an inductive position sensor (1) for a rotating electrical machine comprising a printed circuit board on which are arranged 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 being housed in at least one casing (10), characterized in that it comprises means (180, 181, 182, 183) for circulating fluid to allow the circulation of a fluid to the inside of a rotor shaft of the electrical machine via at least one channel (17). Figure 7.

Description

Title of the invention: Inductive position sensor with improved fluid circulation system

[0001] The present invention relates to the field of position sensors. And more particularly to an 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, facing the target and 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 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 and can then be glued, soldered, screwed, or clipped to the housing of an engine.

[0007] The disadvantage of these prior art sensors stems from the fact that they do not themselves allow for good lubrication of the electric motor.

[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.

[0009] To this end, 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 emitting element intended to emit an oscillating magnetic field towards a rotating target to generate a modified oscillating magnetic field, and at least a receiving device designed to detect the modified oscillating magnetic field, the sensor being housed in at least one casing,

[0010] The sensor includes fluid circulation means to allow the circulation of a fluid into the interior of a rotor shaft of the electric machine (3) via at least one channel.

[0011] These means allow the fluid to be channeled and directed to the channel. This prevents the fluid from dispersing.

[0012] According to one embodiment of the invention, the inductive position sensor comprises a first channel opening between an internal surface of the housing and the target and a second channel formed from the internal surface of the housing.

[0013] According to one embodiment of the invention, the fluid circulation means are formed at the level of an internal surface of the housing.

[0014] According to one embodiment of the invention, the fluid circulation means are formed by at least one area that is thinner than the rest of the surface of the housing.

[0015] This area allows the fluid to be channeled and directed to the channel. This prevents the fluid from dispersing.

[0016] According to one embodiment of the invention, the underthickness zone is arranged at the level of the arrival of the first channel and the entrance of the second channel.

[0017] According to one embodiment of the invention, the dimensions of the area under thickness are calculated to optimize the channeling of the fluid.

[0018] According to one embodiment of the invention, the area under thickness forms a hollow whose depth is between 0.1 mm and 3 mm.

[0019] According to one embodiment of the invention, the fluid circulation means also include at least one groove formed at the level of an internal surface of the casing and opening into a thinner area.

[0020] The presence of at least one groove allows the fluid to be channeled and conducted via the groove towards the area under thickness and thus towards the channel.

[0021] According to one embodiment of the invention, the fluid circulation means also include a rim disposed at the edge of the zone, opposite to the one where at least one groove opens.

[0022] Thus the fluid which arrives in the area under thickness via the groove and the first channel, is contained in the area thanks to the rim or wall and evacuated towards the second channel.

[0023] The invention also relates to an electrical machine comprising a sensor according to the invention.

[0024] 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:

[0025] - Fig. 1 is a representation of the sensor according to the invention in a first face,

[0026] - [Fig. 2] is a representation of the sensor according to the invention according to a first face without lid,

[0027] - [Fig. 3] is a representation of the sensor according to the invention with the target,

[0028] - [Fig. 4] is a schematic representation of a longitudinal cross-sectional view of the electric machine with sensor according to one embodiment of the invention a), according to another embodiment b),

[0029] - [Fig. 5] is a representation of the sensor according to the invention with a cap,

[0030] - [Fig. 6] is a longitudinal cross-sectional representation of the sensor according to a mode of the realization of the invention,

[0031] - [Fig. 7] is a representation of a detail of the sensor according to an embodiment of the invention,

[0032] - [Fig.8] is a schematic representation of the sensor according to a mode of realization of the invention with different zones of sub-thickness.

[0033] The invention relates to an inductive position sensor 1, as illustrated in [Fig.1] to [Fig.3] incorporating means for circulating the lubricating fluid of an electrical machine.

[0034] 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.

[0035] The inductive position sensor 1 and the target are intended to be mounted in a rotating electrical machine 3, illustrated [Fig.4] a and b, such as an electric motor of an electric or hybrid vehicle comprising a rotor 32 rotating relative to a stator 33. The angular position of the rotor 32 is determined relative to the stator 33.

[0036] According to one embodiment of the invention, the sensor is fixed to the cover of the electrical machine by a screw-type fixing system 19.

[0037] As illustrated [Fig.4] a and b, the target 2 is mounted on one end of a shaft 31 of the rotor 32 to modify a magnetic field emitted by a transmitter.

[0038] 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 32. The target 2 comprises several blades 21 which provide a repeating and periodic magnetic field pattern with respect to the rotation axis of the rotor.

[0039] According to one embodiment of the invention, the sensor 1 is arranged opposite the target 2 at the end of the rotor shaft 31. More specifically, the sensor 1 The position sensor is fixed relative to the stator 33, opposite the target 2 at the end of the rotor shaft 31. Therefore, in order of positioning on the shaft, there are the rotor / stator 32, 33, then the target 2, then the position sensor 1. These elements are arranged coaxially with the X-axis of the rotor shaft.

[0040] According to one embodiment of the invention, the sensor 1 is through-hole, that is to say the shaft 31 of the rotor passes through the center of the sensor [Fig. 4a].

[0041] 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 31 of the rotor [Fig. 4b].

[0042] The inductive position sensor 1 includes at least one printed circuit board 12 (PCB) comprising 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.

[0043] This printed circuit board 12 includes a receiver 14 for detecting the modified oscillating magnetic field and transmitting it to a signal processing unit 6 to measure the angular position of the target 2. The modified oscillating magnetic field generates an electromotive force at a given frequency in the receiver 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 the target 2.

[0044] The inductive position sensor 1 is fixed relative to the stator 33. The transmitting element 13 and the receiving device 14 of the inductive position sensor 1 are positioned opposite the target 2.

[0045] According to one embodiment of the invention, the receiving device 14 comprises several windings and has a circular cross-section and more specifically an annular shape.

[0046] According to one embodiment of the invention, the number of windings of the receiving device 14 is proportional to the number of blades 21 (or angular sectors) of the target 2.

[0047] 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.

[0048] The printed circuit board 12, the transmitting elements 13 and the receiving device 14 are housed in at least one housing 10 and supported by a base of the housing 10. This housing forms the body 10 of the sensor 1.

[0049] According to one embodiment of the invention, the signal processing unit 6 is positioned on the same substrate as the transmitting and receiving elements or on another substrate, housed in the casing.

[0050] According to one embodiment of the invention, the housing 10 is closed by a cover 11.

[0051] The sensor 1 according to the invention is configured to allow the circulation of a fluid up to the inside of the shaft 31 of the rotor 32.

[0052] For this purpose, the sensor 1 includes a first fluid inlet channel 16. This channel 16 is configured to be in communication with a fluid reservoir 4 of the machine.

[0053] According to one embodiment of the invention, this first channel 16 is formed in the body 10 of the sensor 1. In this case, the sensor 1 has a plug 15 to close the opening made in the body of the sensor 1 during the creation of the first channel [Fig.5].

[0054] According to one embodiment of the invention, the first channel 16 is an added element which is linked to the body of the sensor by welding, gluing, clipping or any other method of retention.

[0055] According to one embodiment of the invention, the first channel 16 is arranged coaxially to the X axis of the rotor and perpendicular to the card 12 of the printed circuit of the sensor 1.

[0056] According to one embodiment of the invention [Fig.6], the first channel 16 is opened by a first end 165 which is configured to be positioned at the level of a fluid reservoir 4, so as to receive the fluid from the reservoir by gravity or the fluid under pressure.

[0057] According to one embodiment of the invention, the sensor 1 comprises a second channel 17 formed from the lower part of the sensor body 1. The lower part is that on which the printed circuit board rests, as opposed to the upper part, which is open and on which the cover is positioned. More precisely, the second channel is formed from the inner face 101 of the housing 10, oriented towards the machine 3.

[0058] According to one embodiment of the invention, the second channel 17 is overmolded or molded with the housing 10.

[0059] According to one embodiment of the invention, the second channel 17 is arranged parallel to the X axis of the rotor and therefore parallel to the first channel 16.

[0060] According to a second variant of the invention, the first channel 16 extends to the second channel 17.

[0061] According to one embodiment of the invention, the second channel 17 is a channel 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.

[0062] According to one embodiment of the invention, the longitudinal opening of the channel is oriented towards the first channel.

[0063] According to one embodiment of the invention, the second channel 17 is configured to open into the shaft 31 of the rotor 32. The shaft 31 of the rotor 32 has openings 34 allowing the fluid circulating in the second channel 17 to be distributed into the electric machine 3 through the center of the X-axis of the rotor shaft by means of the force A centrifugal force propels the fluid against the shaft walls. This configuration prevents the fluid from dispersing directly at the reservoir outlet. With this setup, the fluid is drawn to the center of the rotor shaft and then dispersed throughout the rotor, resulting in improved lubrication.

[0064] According to one embodiment of the invention, the second end 166 of the first channel 16 opens between the lower part of the body 10 of the sensor and the target 2. The fluid can thus flow by gravity from the first channel 16, to a second channel 17, circulating between the lower part of the body of the sensor and the target.

[0065] In the context of the invention, the internal surface 101 of the housing 10 includes visible fluid circulation means 180 [Fig.7].

[0066] According to one embodiment of the invention, the fluid circulation means 180 are formed by at least one zone 181 that is thinner than the rest of the surface of the housing, located at the inlet of the first channel 16 of the fluid circulation means 180 and the inlet of the second channel 17. More specifically, the internal surface 101 of the housing 10 has a zone 181 forming a hollow between the inlet of the first channel 16 and the inlet of the second channel 17.

[0067] According to one embodiment of the invention, the dimensions of the thinner zone 181 are calculated to optimize fluid channeling. Figures [Fig. 8] a), b), and c) illustrate different dimensions of the thinner zone 181.

[0068] According to one embodiment of the invention, the zone 181 in the underthickness forms a hollow whose depth is between 0.1 and 3 mm, and for example 0.5 mm.

[0069] This zone allows the fluid to be channeled and conducted from the first channel 16 to the second channel 17. This prevents the fluid from dispersing, visible [Fig.8].

[0070] In the context of the invention, the fluid circulation means 180 also include at least one groove 182 formed on the internal surface 101 of the housing. This groove has the shape of an incomplete circle and opens into the area 181 in a reduced thickness.

[0071] According to one embodiment of the invention, the sensor has at least 2 grooves 182 and for example 3 grooves 182.

[0072] According to one embodiment of the invention, the grooves are spaced apart from each other.

[0073] According to one embodiment of the invention, the grooves are arranged in spirals.

[0074] When the target 2 rotates, the direction C of rotation is indicated by the arrow on the [Fig.8], At least some of the fluid arriving from conduit 16 is dispersed in the area between the target and the inner surface of the housing. The presence of at least one groove allows the fluid to be channeled (arrow F) and directed via the groove to the thinner area and thus to the second channel 17.

[0075] In the context of the invention, according to one embodiment of the invention, the fluid circulation means 180 also include a rim 183 disposed at the edge of the zone, opposite to that into which at least one groove 182 opens.

[0076] According to one embodiment of the invention, the rim forms a wall whose height is between 0.1 and 3 mm, and for example 0.5 mm.

[0077] Thus the fluid which arrives in zone 181 in a thin layer via the groove and the first channel 16, is contained in zone 181 thanks to the rim or wall and evacuated towards the second channel 17.

[0078] One advantage of these fluid circulation means 180 is that they allow for a reduced distance between the target and the printed circuit board, which is an important criterion for signal accuracy. These means also allow for a completely cylindrical antenna 13, 14, which helps maintain good signal accuracy even in the event of target beat phenomena.

[0079] 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 electric machine 3, and for example of the gears of the electric machine 3.

[0080] Thus such a sensor according to the invention allows the lubrication of the elements of the electrical machine without additional system.

[0081] The invention also relates to an electrical machine 3 comprising a sensor 1 as described above, according to the two variants.

[0082] 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. An inductive position sensor (1) for a rotating electrical machine comprising a printed circuit board (12) on which are disposed 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 being housed in at least one casing (10), characterized in that it comprises fluid circulation means (180) for allowing the circulation of a fluid into the interior of a rotor shaft (31) of the electrical machine (3) via at least one channel (16, 17), a first channel (16) opening between an internal surface (101) of the casing (10) and the target (2) and a second channel (17) formed from the internal surface (101) of the casing (10), the second channel (17) being configured to open into the shaft (31) of the rotor (32).

2. Inductive position sensor (1) according to claim 1, wherein the fluid circulation means (180) are formed at an internal surface (101) of the housing (10).

3. Inductive position sensor (1) according to claim 1 or 2, wherein the fluid circulation means (180) are formed by at least one area (181) that is thinner than the rest of the surface of the housing (10).

4. Inductive position sensor (1) according to claim 3 when it depends on claims 2 to 3, wherein the underthickness area (181) is disposed at the inlet of the first channel (16) and the inlet of the second channel (17).

5. Inductive position sensor (1) according to any one of claims 3 to 4, wherein the area (181) in underthickness forms a hollow whose depth is between 0.1 mm and 3 mm.

6. Inductive position sensor (1) according to any one of claims 1 to 5, wherein the fluid circulation means (180) also comprise at least one groove (182) formed at the level of an internal surface (101) of the housing and opening into a sub-thickness area (181).

7. An inductive position sensor (1) according to any one of claims 1 to 5, wherein the fluid circulation means (180) comprise

8. also a rim (183) disposed at the edge of the zone, opposite the one where at least one groove (182) opens. Electric machine (3) comprising a sensor (1) according to any one of claims 1 to 7.