Motor with integrated control with air circulation in the electronic control unit

Abstract

The invention relates to a motor (10) with integrated control, comprising: - an electric machine (11) provided with at least one rotating part mounted on a drive shaft (40); - an electronic control unit (12) for controlling the electric machine; - a casing comprising a first cavity (21) in which the electric machine (11) is housed and a second cavity (22) in which the electronic control unit (12) is housed, the drive shaft passing through both the first and second cavities (21, 22), the second cavity being closed by at least one wall (23) close to the first cavity; and - an air-mixing device (50, 60), housed in the second cavity (22) and generating an air circulation within the second cavity so as to homogenise an air temperature within the second cavity.

Description

DESCRIPTION TITLE: Integrated control motor with air circulation in the electronic control unit TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an integrated control motor, or "Smart Motor", in which air circulation is integrated into the electronic control unit of the motor.

[0002] The invention finds applications in the fields of actuators, motorization and electrical generation, particularly applied to aeronautics. It finds, in particular, applications in the field of integrated control motors, for example for aircraft. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0003] In aeronautics, as in other fields, it is increasingly common to use integrated control motors (or Smart Motors, in English terminology) which have the advantage of integrating, in the same housing, both an electric machine and its electronic control unit. The electric machine, for example a motor or a generator, and the electronic control unit, for example a power electronic module, are arranged in two separate cavities of the same housing.

[0004] Figure 1 shows a front perspective view (drawing A), a rear perspective view (drawing C) and a cross-sectional view (drawing B) of an integrated control motor 10. This integrated control motor 10 comprises an electric machine 11 and an electronic control unit 12, both housed in the same casing 20. This casing 20 comprises two separate cavities: a first cavity 21 in which the electric machine 11 is housed and a second cavity 22 in which the electronic control unit 12, also called the control unit, is housed.

[0005] Although such integrated control motors have advantages, such as compactness, they also have the disadvantage that the control unit 12, in its conventional form, does not withstand high temperatures well; in fact, at high temperatures, i.e. above approximately 125°C, the service life of the electronic components is considerably reduced. However, in operation, the electrical machine of an integrated control motor generates high heat which tends to increase the ambient temperature inside the first cavity 21, up to more than 160°C. The first and second cavities being communicating, the ambient air of the second cavity 22 reaches temperatures well above what the components of the control unit 12 can withstand. Thus, although the electrical machines are able to withstand temperatures of up to 160°C, or even 180°C, the maximum temperature supported by the control unit greatly limits the applications of integrated control motors.

[0006] A known solution for cooling the integrated control motor is to install cooling fins on the drive shaft at the rear of the electric machine to create a flow of fresh air to cool the motor housing. However, this solution does not prevent the air in the first cavity from heating the air inside the second cavity.

[0007] Another known solution for improving the temperature resistance of the control unit is to relocate the control unit to a so-called cool zone. This solution involves relocating all the electronic components forming the control unit and connecting them, via electrical harnesses, to the electric machine. However, such a solution is not applicable to motors with integrated control because, due to its relocation, the control unit is no longer arranged in the same housing as the electric machine and is therefore no longer "integrated".

[0008] Another known solution to limit the temperature rise within the control unit is to oversize the electrical machine so that it can operate at lower temperatures, for example in the order of 100 to 110°C, and not heat the control unit. This solution, which is widely used in certain fields such as industry and transport, results in an increase in the mass of the integrated control motor, which is incompatible with aeronautical constraints which require rather reducing the mass of the elements and components of the aircraft.

[0009] Another solution to improve the temperature resistance of the control unit is to select so-called "high temperature" electronic components, which have the particularity of resisting high temperatures. However, this solution cannot be applied in aeronautics because this technology is new and in full development. It is therefore particularly expensive and most of the components are difficult to obtain or even unavailable. In addition, when they exist, these so-called high-temperature components often have a low level of reliability.

[0010] Yet another solution considered to improve the temperature resistance of the control unit is to create openings in the second cavity to renew the air within said cavity. However, these openings cause a pollution problem, in particular dust pollution, at the level of the electronic components of the control unit, one of the effects of which is to deteriorate said electronic components and therefore to reduce their lifespan, which is contrary to the desired goal.

[0011] A final known solution for improving the temperature resistance of the control unit consists of integrating dedicated cooling into the integrated control motor. This cooling, for example in the form of a fluid circuit (for example air or a liquid), is integrated inside the housing to cool not only the components of the control unit but also the electric machine. This fluid cooling is generally associated with thermal insulation installed between the electric machine and the control unit, for example at the junction between the first cavity housing the electric machine and the second cavity housing the control unit. This thermal insulation is generally in the form of one or more thermal partitions 30, mounted between the two cavities 21, 22 so that the control unit 12 cooled by the fluid flow does not heat up in contact with the hot ambient air of the first cavity.

[0012] With such thermal insulation, the second cavity 22 is substantially closed, sealed, without fluid exchange between the first and second cavities. In addition, the cards and other electronic components (fig. 2) forming the control unit 12 are static elements, which are not rotating in the second cavity; the air which prevails in this second cavity is therefore stagnant air, which does not circulate. Furthermore, for reasons of space, the electronic cards within the second cavity 22 are generally close to each other, which does not promote air circulation. However, it has been found that certain areas inside the second cavity 22 are hotter than others. Indeed, some electronic boards generate more heat than others, which causes hot spots. As shown in Figure 2, which represents a temperature map of the interior of the second cavity, the hot zones Zc are located in the same half of the second cavity, while cold zones Zf are located in the opposite half of the second cavity. Due to the stagnation of air within the second cavity, there is no heat exchange within said second cavity and the components located in the hot zones Zc, or hot spots, have an even shorter lifespan than those located in the cold zones Zf of the second cavity.

[0013] There is therefore a real need for technology to improve the temperature resistance of the control unit components by preventing the creation of hot spots in the second cavity. SUMMARY OF THE INVENTION

[0014] To address the above-mentioned problems of hot spots in the second cavity of the integrated control engine, the applicant proposes an integrated control engine in which an air mixing device is installed in the second cavity in order to homogenize the air temperature within said second cavity and thus improve the thermal performance of the engine.

[0015] According to a first aspect, the invention relates to an integrated control motor comprising: an electric machine provided with at least one rotating part mounted on a drive shaft, an electronic control unit for controlling the electric machine, a casing comprising a first cavity in which the electric machine is housed and a second cavity in which the electronic control unit is housed, the first and second cavities both being traversed by the drive shaft, the second cavity being closed by at least one wall near the first cavity, characterized in that it comprises an air mixing device, housed in the second cavity and generating a circulation of air within the second cavity so as to homogenize an air temperature within said second cavity.

[0016] Circulating an airflow within the second cavity thermally homogenizes the ambient air in the second cavity to prevent hot spots. With thermally homogenous ambient air, the control unit's components have a more uniform service life, extending the overall life of the control unit.

[0017] Advantageously, the air mixing device is mounted integrally around the drive shaft and driven in rotation by said drive shaft.

[0018] Mounting the air mixing device directly on the drive shaft ensures rotation of said device while avoiding the addition of rotation equipment that would take up too much space in the space available within the second cavity.

[0019] In addition to the features just mentioned in the preceding paragraph, the integrated control motor according to one aspect of the invention may have one or more additional features from among the following, considered individually or according to all technically possible combinations: the air mixing device comprises at least one agitator element mounted integrally on the drive shaft, in the clear zone of the second cavity. the agitator element is a fin extending axially along the drive shaft. the air mixing device comprises several agitator elements distributed along the periphery of the drive shaft. the agitator element has a generally rectangular shape with at least one projecting portion extending radially between electronic cards and components within the second cavity.the agitator element is a blade extending radially from the drive shaft towards a circular wall of the second cavity. the air mixing device comprises several agitator elements, positioned concentrically around each other around the drive shaft. the stirring elements are integral with each other and positioned between the wall of the second cavity and an electronic card. the stirring element is a curved blade. the casing has drainage orifices located in a wall of the second cavity and cooperating with the air mixing device to thermally homogenize the air within said second cavity.

[0020] According to a second aspect, the invention relates to an electrical machine for aircraft, characterized in that it comprises at least one motor with integrated control according to the first aspect. BRIEF DESCRIPTION OF THE FIGURES

[0021] Other advantages and characteristics of the invention will appear on reading the following description, illustrated by the figures in which:

[0022] Figure 1, already described, represents a front perspective view (drawing A), a rear perspective view (drawing B) and a cross-sectional view (drawing C) a motor with integrated control according to the state of the art;

[0023] Figure 2, already described, represents a temperature map of the interior of the second cavity of the engine;

[0024] Figure 3 shows a schematic cross-sectional view of an integrated control motor according to the invention, on which several embodiments are shown;

[0025] Figure 4 schematically represents a side view in partial section (drawing A), a partial perspective view (drawing B) and a complete perspective view (drawing C) of an integrated control motor according to a first embodiment of the invention, as well as a sectional view of a fin of an embodiment of the mixing device integrated in the second cavity of the motor (drawing D);

[0026] Figure 5 schematically represents a side view in partial section (drawing A), a partial perspective view (drawing B) and a complete perspective view (drawing C) of an integrated control motor according to a second embodiment of the invention;

[0027] Figure 6A and Figure 6B schematically represent the side views in partial section of the integrated control motor according to the first and second embodiments respectively, on which the trajectories of the air flows generated by the air mixing device are indicated; and

[0028] Figure 7 schematically represents a perspective view of a third embodiment of the stirring device of an integrated control motor according to the invention.

[0029] In the figures, identical elements are identified by identical references. For reasons of readability of the figures, the size scales between the elements represented are not respected. DETAILED DESCRIPTION

[0030] An exemplary embodiment of an integrated control motor, the second cavity of which is equipped with an air mixing device ensuring thermal homogenization within the cavity, is described in detail below, with reference to the appended drawings. This example illustrates the characteristics and advantages of the invention. It is however recalled that the invention is not limited to this example.

[0031] An example of an integrated control motor according to the invention is shown, in section, in Figure 3. This section of the integrated control motor of the invention is a cross section along the YZ plane of the XYZ reference frame, where Z is the longitudinal direction, Y is the radial direction and X is the transverse direction. The integrated control motor 10, more simply called motor, comprises an electrical machine 11 housed in the first cavity 21 of the casing 20 and a control unit 12 housed in the second cavity 22 of said casing 20. The first and second cavities are distinct from each other, separated by one or more thermal partitions 30.

[0032] The motor 10 further comprises a drive shaft 40 which passes through the casing 20 from one side to the other and extends along the longitudinal axis Z. Indeed, in order to reduce the forces on the bearings of the drive shaft, it is chosen to use, in the motor of the invention, a so-called “through” shaft which passes not only through the first cavity 21 but also through the second cavity 22 of the casing 20. Indeed, although the electronic components of the control unit 12 are not integral with the drive shaft 40 (and are therefore not driven in rotation by said shaft), they are distributed around the drive shaft 40 which passes through the second cavity 22 in its center. The invention proposes to use the drive shaft 40 present in the second cavity 22 to drive an air mixing device 50 and / or 60 in rotation. The rotation of this air mixing device 50 and / or 60 makes it possible to generate a circulation of air within the second cavity 22, in particular between the different components and electronic cards 120 of the control unit 12. This circulation of air inside the second cavity 22 makes it possible to homogenize, or standardize, the temperature of the air prevailing in said second cavity so as to avoid the creation of hot spots. Indeed, the mixing of the air prevailing in the second cavity makes it possible to mix, or blend, the cold air from the cold zones Zf with the hot air from the hot zones Zc so as to obtain thermal uniformity within the second cavity 22.

[0033] The air mixing device 50, 60, more simply called the mixing device, is mounted on the drive shaft 40 in a fixed manner. According to the embodiments, the air mixing device may be a part or a set of parts added and fixed on the drive shaft 40, for example by welding or brazing or any other assembly method; alternatively, the mixing device 50, 60 may be manufactured in a single piece with the drive shaft or a part of the drive shaft, for example by stamping, die-stamping or additive manufacturing or any other manufacturing method.

[0034] The stirring device comprises one or more stirring elements, or mixers, integral with the drive shaft and installed in a clear area of ​​the second cavity where the space requirement is smaller, i.e. an area free of electronic components or cards 120 or an area where the electronic components and cards 120 are relatively spaced apart. The stirring element(s) may, for example, be so-called “axial” stirring elements, installed in the center of the second cavity 22 and extending mainly along the longitudinal axis Z, along the drive shaft 40; the stirring device comprising these axial stirring elements is a so-called “axial” device, referenced 50 in FIG. 3; this axial stirring device 50, essentially longitudinal, is not very extended radially.On the contrary, the agitator element(s) may, for example, be so-called “radial” agitator elements, installed at one end of the second cavity 22 and extending mainly along the radial axis Y, from the shaft. drive 40 towards the cylindrical wall of the casing 20; the stirring device comprising these radial stirring elements is a so-called “radial” device, referenced 60 in FIG. 3; this radial stirring device 60 is not very extended longitudinally.

[0035] According to an alternative, the second cavity 22 can house two stirring devices, namely an axial stirring device 50 comprising one or more axial stirring elements and a radial stirring device 60 comprising one or more radial stirring elements.

[0036] According to another alternative, the stirring device can extend mainly in an oblique direction, intermediate between the Y direction and the Z direction, as shown in the example of figure 7. The stirring device 70, still integral with the drive shaft 40, then comprises stirring elements 71 extending in the oblique direction.

[0037] Figure 4 shows an example of an axial stirring device 50 comprising a plurality of axial stirring elements 51 extending at the periphery of the drive shaft 40 along the longitudinal axis Z. Drawing A of Figure 4 shows a side view, in partial section, of a motor 10 equipped with the axial stirring device 50. Drawing B of Figure 4 shows a partial perspective view of the stirring device 50 within the second cavity 22 of the motor 10. Drawing C of Figure 4 shows a complete perspective view of a motor 10 equipped with the stirring device 50. Drawing D of Figure 4 shows an example of a section of a stirring element 51 of the stirring device 50. In this embodiment, the stirring elements 51 are fins distributed substantially regularly around the periphery of the drive shaft 40.The vanes 51, driven by the drive shaft 40, rotate and stir the air in the center of the second cavity, which creates an air circulation throughout the second cavity, as indicated by the arrow in Figure 6A.

[0038] In this embodiment, the number of fins 51 is defined according to the applications and / or the engine model and the shape of the fins 51 is chosen so as to match as closely as possible the shape of the cards and electronic components 120 to be cooled while guaranteeing the best ventilation performance. In the example of Figure 4, the fins 51 have a generally rectangular shape with one or several radial protrusions making it possible to accelerate the air between the electronic cards and components and, thus, to further improve the circulation of the air. More precisely, each fin 51 of the example of FIG. 4 comprises: a rectangular portion 52 having a secured side 52a, secured to the drive shaft 40, a free side 52b, opposite the secured side 52a, and two external sides 52c each connecting a free side and a secured side. The secured sides 52a and free sides 52b are preferably larger than the external sides; and a projecting portion 53 which extends from the free side 52b of the rectangular portion 52, in the radial direction Y.

[0039] In the example of Figure 4, the projecting portion 53 extends at one end of the rectangular portion 52- (for example in the continuity of an external side 52c). Alternatively, the projecting portion 53 can extend from the center of the rectangular portion or from any location on the free side 52b of the rectangular portion, depending on the available space. In an alternative, several projecting portions 53 extend from the free side 52b of the rectangular portion 52.

[0040] The shape and dimensions of the rectangular portion 52 and the projecting portion 53 of the fins 51 are defined as a function of the space within the second cavity 22, that is to say as a function of the space available between the cards and electronic components of the control unit 12 in the vicinity of the drive shaft 40. The more the environment around the drive shaft is clear of all cards and / or electronic components, the larger the rectangular portion 52 and / or the projecting portion 53 of the fins 51 can be.

[0041] Of course, the shape of the fins may be different from that shown in Figure 4. Other shapes of fins 51 may be envisaged depending on the applications and / or the space available. The fins 51 may, for example, have a semi-ovoid section (i.e. with a curved free side) or a sinusoidal shape (i.e. the free and integral sides of which form a sort of S), or any other profile shape conceivable for ventilation blades.

[0042] Figure 5 shows an example of a radial stirring device 60 comprising a plurality of stirring elements 61 extending concentrically around the drive shaft 40 along the longitudinal axis Y. The Drawing A of Figure 5 shows a side view, in partial section, of an engine 10 equipped with the radial stirring device 60. Drawing B of Figure 5 shows a partial perspective view of the radial stirring device 60 within the second cavity 22 of the engine 10. Drawing C of Figure 5 shows a complete perspective view of an engine 10 equipped with the radial stirring device 60. In this embodiment, the stirring elements 61 are blades which extend radially and concentrically around the drive shaft 40 and which are positioned along the wall of the second cavity close to the thermal partition 30. Thus, the blades 61, driven by the drive shaft 40, rotate and circulate the air from the cold side of the engine to the hottest part of the second cavity, i.e. the part closest to the engine.This direction of air circulation, represented by the arrow in Figure 6B, not only makes it possible to thermally homogenize the air, but also to obtain a forced convective exchange with the external wall 24 of the second cavity which is the coldest wall of said cavity.

[0043] In this embodiment, each blade 61 is a curved blade at least partially surrounding the drive shaft 40. The radial stirring device 60 may comprise a single blade 61, for example of helical shape, secured to the drive shaft. It may, preferably, comprise several blades 61 secured both to each other and to the drive shaft. The number of blades 61 of the stirring device 60 and the shape of the blades may vary depending on the applications, the available space and / or the engine model.

[0044] In one embodiment, the blades 61 may be fixed to one another, for example by their ends, one of the blades 61 also being fixed to the drive shaft.

[0045] In another embodiment, shown in Figure 5, the radial stirring device 60 comprises several blades 61, each in the shape of an arc of a circle, arranged in a staggered manner relative to each other so as to surround the drive shaft 40. The blades 61 are each fixed to a support 62, itself secured to the drive shaft 40. In the example of Figure 5, the support 62 is a disc, positioned in the XY plane and secured to the drive shaft by its internal contour 62a (i.e. the internal diameter of the disc). The blades 61 are fixed to the support disc 62, for example by welding, brazing or gluing (or any another method of attachment described previously in paragraph

[0033] ), via one of their lateral faces 61a. The disc-support assembly 62 and blades 61 is positioned along the internal wall 23 of the second cavity 22, the internal wall 23 being the wall closest to the first cavity 21, that is to say the one located near the thermal partition 30.

[0046] Depending on the applications and / or the motor, the blades 61 may have different shapes and dimensions. They may, for example, surround the drive shaft at an angle of approximately 30°, 90° or 180° or any other angle. The thickness of the blades 61 may also vary from one blade to another or along the length of the blade. The curvature of the blade 61 and its length may also vary. The dimensions of the blades 61 and of the support disc 62 may be adapted according to the size of the second cavity 22, that is to say according to the space available between the internal wall 23 of the second cavity 22 and the electronic cards inside said second cavity. The clearer the environment along the inner wall 23, the larger the width of the blades 61 (i.e. the dimension of the blades in the longitudinal direction) and / or the diameter of the support disc 62 can be.

[0047] In some embodiments, the electronic cards within the second cavity may be arranged to further promote airflow from the outer wall 24 to the inner wall 23.

[0048] Depending on the models, the motors 10 may include drainage orifices, located in particular in the wall of the second cavity 22, and whose role is to allow the evacuation of condensates. An embodiment of the invention, shown in FIG. 3, uses these drainage orifices in cooperation with the stirring device 50, 60 to stir the air within the second cavity. These drainage orifices, referenced 26 in FIG. 3, are located in the circular wall 25 of the second cavity, for example at the junction between the circular wall 25 and each of the internal 23 and external 24 walls. These drainage orifices 26 collaborate with the stirring device to force the circulation of air inside the second cavity 22, between the cards and electronic components 120.

[0049] Although described through a number of examples, variations and embodiments, the integrated control motor according to the invention includes various variations, modifications and improvements which will be obvious to those skilled in the art, it being understood that these variations, modifications and improvements are part of the scope of the invention.

Claims

CLAIMS

1. An integrated control motor (10) comprising: - an electric machine (11) provided with at least one rotating part mounted on a drive shaft (40), - an electronic control unit (12) for controlling the electric machine, - a casing comprising a first cavity (21) in which the electrical machine (11) is housed and a second cavity (22) in which the electronic control unit (12) is housed, the first and second cavities (21, 22) both being crossed by the drive shaft, the second cavity being closed by at least one wall (23) near the first cavity, characterized in that it comprises an air mixing device (50, 60), housed in the second cavity (22) and generating a circulation of air within the second cavity so as to homogenize a temperature of the air within said second cavity, that the air mixing device (60) comprises several agitator elements (61) mounted integrally on the drive shaft (40),in the clear area of ​​the second cavity (22) and positioned concentrically with each other around the drive shaft (40) and that the agitator element (61) is a blade extending radially from the drive shaft (40) towards a circular wall (25) of the second cavity.,

2. Integrated control motor according to claim 1, characterized in that the air mixing device (50, 60) is mounted integrally around the drive shaft (40) and driven in rotation by said drive shaft.

3. An integrated control motor according to claim 2, characterized in that the agitator element (51) is a vane extending axially along the drive shaft (40).

4. Integrated control motor according to claim 3, characterized in that the air mixing device (50) comprises several agitator elements (51) distributed along the periphery of the drive shaft (40).

5. An integrated control motor according to claim 3 or 4, characterized in that the agitator element (51) has a generally rectangular with at least one projecting portion (53) extending radially between electronic boards and components within the second cavity (22).

6. Integrated control motor according to claim 1, characterized in that the agitator elements (61) are integral with each other and positioned between the wall (23) of the second cavity and an electronic card.

7. Integrated control motor according to any one of claims 1 to 6, characterized in that the stirring element (61) is a curved blade.

8. Integrated control motor according to any one of claims 1 to 7, characterized in that the casing comprises drainage orifices (26) located in a wall of the second cavity and cooperating with the air mixing device (50, 60) to thermally homogenize the air within said second cavity.

9. Electrical machine for aircraft, characterized in that it comprises at least one integrated control motor (10) according to any one of the preceding claims.

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