Electronic assembly with sensor protection means

Abstract

The present invention relates to an electronic assembly (30) of an electrical machine, the electronic assembly (30) comprising at least one printed circuit board (50) on which is fixed a sensor (17) disposed in a metallic housing (19), the sensor (17) being arranged so as to be opposite an electromagnetic target (15) of a machine part of the electrical machine, the housing (19) having an opening (191), at the level of the sensor (17), closed by a sensor protection means (18). Figure for the abstract: Fig. 1.

Description

Title of the invention: Electronic assembly with sensor protection means

[0001] The present invention relates to an electronic assembly with a sensor protection means for a rotating electrical machine.

[0002] A rotating electrical machine is an electromechanical device, preferably polyphase, that allows the conversion of electrical energy into mechanical energy, or vice versa.

[0003] In a known manner, the rotating electrical machine includes an electronic assembly which supplies the rotor and stator with current, which allows optimal control of the electrical machine.

[0004] To perform the control, it is necessary to know the position of the rotor and its rotational speed. For this, it is possible to use a sensor at the end of the shaft.

[0005] A magnetic target is placed at the end of the rotor, i.e., at the end of the shaft, and a sensor is positioned opposite it on the electronic assembly. For the measurement to be effective, it is necessary to ensure a small air gap between the magnetic target and the sensor at the end of the shaft. However, because one component is on the machine side and the other on the electronic side, there are many links in the dimensional chain, which generates a large dispersion in the air gap value.

[0006] Furthermore, since the inverter is a closed box, there is a significant thickness of aluminum between the Hall effect sensor and the magnetic target. One solution is to machine the aluminum to reduce its thickness. However, this machining is expensive.

[0007] Furthermore, since aluminum casting tolerances are quite large, the presence of aluminum will increase the air gap. Indeed, a mounting clearance must be guaranteed between the sensor and the casting, and another mounting clearance between the magnetic target and the casting.

[0008] The present invention therefore aims to overcome one or more of the drawbacks of prior art devices by proposing an improved means of protection for the sensor, which allows for an optimum air gap to be maintained.

[0009] To this end, the present invention proposes an electronic assembly for an electrical machine, the electronic assembly comprising at least one printed circuit board on which is fixed a sensor disposed in a metallic housing, the sensor being disposed so as to be opposite an electromagnetic target of a machine part of the electrical machine,

[0010] the housing having an opening, at the level of the sensor, closed by a means of protecting the sensor.

[0011] The opening is thus formed so that there is no more aluminum between the magnetic target and the sensor.

[0012] According to one embodiment of the invention, the protective means is a plastic cover.

[0013] According to one embodiment of the invention, the thickness of the protective means is between 0.5 and 1.2 mm.

[0014] Such a thickness of protective means makes it possible to obtain a reduced air gap.

[0015] According to one embodiment of the invention, the protective means has a shape circular.

[0016] According to one embodiment of the invention, the diameter of the opening and of the protection means is defined so as to be larger than that of the magnetic target.

[0017] According to one embodiment of the invention, the diameter of the protective means is greater than that of the opening.

[0018] According to one embodiment of the invention, the protective means is fixed to the edge of the opening by gluing

[0019] The invention also relates to a method of fixing a means of protecting a sensor of an electronic assembly according to the invention comprising a gluing step.

[0020] According to one embodiment of the invention, the process includes a step of polymerizing the glue in open air or in an oven.

[0021] The invention also relates to an electrical machine comprising an electronic assembly according to the invention.

[0022] 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:

[0023] - [Fig. 1] is a longitudinal cross-sectional view of a part of the machine according to the invention,

[0024] - [Fig.2] is an elevation view of the electronic assembly according to the invention.

[0025] The invention relates to an electronic assembly with a sensor protection means for electrical machine.

[0026] Fig. 1 illustrates a part of the electrical machine 1 concerned by the invention.

[0027] The electrical machine 1 is, for example, a rotating electrical machine 1. By For example, rotating electrical machine 1 is of the generator, alternator, alternator-starter type, whose voltages are between 10 and 60V, and for example are equal to or greater than 48V.

[0028] This rotating electric machine 1 transforms mechanical energy into electrical energy in alternator mode, and can operate in motor mode to transform electrical energy into mechanical energy. The rotating electric machine 1 It comprises a machine part 20 with a housing 10. Inside this housing 10, there is a shaft 11, a rotor 12 fixed to the shaft 11 for rotation, and a stator 13 surrounding the rotor. The rotational movement of the rotor 12 is about an axis X.

[0029] In this example, the housing 10 includes at least one hollow rear bearing 16 carrying, centrally, a ball bearing 12 for the rotational mounting of the shaft 11. In the context of the invention, the rear end 111 of the shaft 11 includes a magnetic target 15. More precisely, the magnetic target 15 is disposed at the end of the shaft 11. According to one embodiment, the target 15 is composed of several magnetic poles.

[0030] In the context of the invention, the electronic assembly 30 includes a sensor 17 arranged opposite the magnetic target 15. This sensor 17 measures the magnetic field and interprets the speed and position of the rotor 12 thanks to the magnetic field generated by the magnetic target 15.

[0031] According to one embodiment of the invention, the electronic assembly 30 comprises a printed circuit board 50 also called PCB (for Print Cart Board according to English terminology).

[0032] According to one embodiment of the invention, the sensor 17 is fixed under the printed circuit board 50. That is to say, on the side of the board facing the machine part 20.

[0033] According to one embodiment of the invention, the electronic assembly 30 comprises an aluminum housing 19 in which the electronic elements are arranged.

[0034] In the context of the invention, the electronic assembly 30 includes a sensor protection means 18 for the sensor 17. This sensor protection means 18 for the sensor 17 is formed by a plastic cover 18. The sensor protection means 18 for the sensor 17 is positioned at an opening 191 formed in the wall of the electronic housing 19 at the sensor 17. The opening 191 is formed in such a way that there is no longer any aluminum between the magnetic target 15 and the sensor 17. The aluminum is replaced by the protection means.

[0035] According to one embodiment of the invention, the protective means 18 has a thickness of between 0.5 and 1.2 mm. According to another embodiment of the invention, the protective means 18 has a thickness of 0.8 mm + / - 0.05 mm tolerance.

[0036] Such a thickness of protective means 18 makes it possible to obtain an air gap 40 of between 4 and 5 mm. According to one embodiment of the invention, the air gap 40 is equal to 4.29 mm, +1.39 / -1.27 mm.

[0037] According to one embodiment of the invention, the protection means 18 has a defined shape so as to be larger than the sensor, for example circular or square.

[0038] According to one embodiment of the invention, the perimeter dl of the opening 191 and the perimeter d2 of the protective means 18 are defined so as to be larger than that of the magnetic target 15 and the sensor 17. In this way, the reduced air gap 40 covers the entire surface of the magnetic target, which improves the accuracy of the measurement by the sensor.

[0039] According to one embodiment of the invention, the protective means 18 has a perimeter d2 greater than that dl of the opening 191. This allows for an overlap between the protective means 18 and the edges 192 of the opening 191 to fix the protective means 18.

[0040] In the context of the invention, the protective means 18 is fixed in a sealed manner to the edge 192 of the opening 191. So as to guarantee the sealing of the electronic assembly 30.

[0041] According to one embodiment of the invention, the protective means 18 is attached to the edge 192 of the opening 191 by gluing. More specifically, the protective means 18 is attached to the edge 192 of the opening 191 with polymerized glue.

[0042] According to one embodiment of the invention, the protective means 18 is fixed to the edge 192 of the opening 191 with a gasket and then screwed in.

[0043] The present invention also relates to an electrical machine 1 comprising such a protection means 18 for sensor 17.

[0044] The present invention also relates to the method of fixing the protective means 18.

[0045] In the context of the invention, the method consists of bonding and polymerizing the adhesive for fixing the protective means 18 simultaneously with at least one other element of the electronic assembly that also requires bonding. According to one embodiment of the invention, another electronic element is a busbar 21, and / or a power connection terminal 22.

[0046] According to one embodiment of the invention, the process includes a polymerization step in open air or in a polymerization oven.

[0047] In this way, the assembly is optimal and less expensive than if the gluing is done for each part separately over time.

[0048] 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

Claims

1. Electronic assembly (30) of an electric machine (1), the electronic assembly comprising at least one printed circuit board (50) on which is fixed a sensor (17) arranged in a metal housing (19), the sensor (17) being arranged so as to be opposite an electromagnetic target (15) of a machine part (20) of the electric machine (1), characterized in that the housing (19) comprises an opening (191), at the level of the sensor, closed by a protection means (18) of the sensor (17), the thickness of the protection means (18) is between 0.5 and 1.2 mm.

2. An electronic assembly (30) of an electric machine according to claim 1, wherein the protective means (18) is a plastic cover.

3. Electronic assembly (30) of an electric machine according to one of claims 1 to 2, in which the protection means (18) has a shape defined so as to be larger than the sensor, for example circular or square.

4. Electronic assembly (30) of an electric machine according to one of claims 1 to 3, in which the perimeter d1 of the opening and the perimeter d2 of the protection means is defined so as to be larger than that of the magnetic target (15).

5. Electronic assembly (30) of an electric machine according to one of claims 1 to 4, in which the perimeter d2 of the protection means (18) is greater than that dl of the opening.

6. Electronic assembly (30) of an electric machine according to one of claims 1 to 5, in which the protective means (18) is fixed to the edge (192) of the opening (191) in a sealed manner, and for example by gluing.

7. Method for fixing a protective means (18) of a sensor (17) of an electronic assembly (30) according to one of claims 1 to 6 comprising a step of sealed fixing, for example gluing, the thickness of the protective means (18) being between 0.5 and 1.2 mm.

8. Fixing method according to claim 7, comprising a step of depolymerizing the glue in the open air or in an oven.

9. Electrical machine (1) comprising an electronic assembly (30) according to one of claims 1 to 8.

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