Compact and quiet electromechanical actuator with synchronous motor

Abstract

The invention relates to an electromechanical actuator comprising a permanent magnet synchronous motor (1a) and a motor control unit, the motor comprising: a cylindrical rotor (3), permanent magnets (12) associated with the rotor and forming magnetic poles, a cylindrical stator (2) arranged coaxially around the rotor and having a plurality of teeth extending radially towards the rotor, and a winding (11) forming a coil around each of the stator teeth, and in which the permanent magnets (12) are ferrite-based, the stator (2) having an external diameter of less than 55 mm, the rotor (3) comprising recesses (31) forming a flux barrier around a longitudinal axis of the rotor, and the permanent magnets are inserted into the rotor recesses. Figure 2

Description

Description Title of the invention: Electromechanical motor actuator compact and low-noise synchro-reluctant Technical field

[0001] — The present invention relates to the field of electric motors and more particularly- lately the synchronous “brushless” electric motors in the ranges of power ranging from a few tens of watts to a few hundred watts. Such motors are for example implemented in electromechanical actuators in the field of home automation installations. These actuators are used in particular to put rotating a shaft or winding tube to drive a roller shutter or blind to cover a window or door of a building. State of the art

[0002] — A “brushless” synchronous electric motor typically comprises a rotor and a stator comprising several windings. In applications where the motor is equipped an electromechanical actuator driving a winding tube in rotation, it is desirable for reasons of space to house the actuator in the tube winding, which imposes strong constraints on the actuator in terms of volume and thermal. In fact, the engine itself is encapsulated in a casing, generally metallic, of the actuator. The diameter of the motor is therefore constrained to a few cent- timers. Under these conditions, it is difficult to ventilate the engine. On the other hand, the actuator may also be subjected to high temperatures when mounted in the winding tube of a roller shutter or blind mounted on the front of a building. The length of the engine is also reduced as much as possible to allow an actuator length suitable for the greatest number of applications.

[0003] — In the field of synchronous “brushless” electric motors, the motor permanent magnet synchronous is increasingly popular, due to its per- forms, particularly in terms of power density and noise, compared to other motors such as cage asynchronous motors. The synchronous motor permanent magnets can be powered by a sinusoidal or trapezoidal signal. It also most often includes Hall effect sensors for the detection of the position of the rotor relative to the stator.

[0004] — However, by reducing the size of the engines, phenomena of re- resonance between the electromagnetic forces occurring within the motor and the mechanical elements of the latter. These resonance phenomena correspond to a noise spectrum that may include peaks in the audible frequency range which prove troublesome for humans. In this type of permanent magnet synchronous motor, it is known to form grooves on the stator to limit the amplitude of "cogging" (variation of torque over one revolution). It is also known to form grooves on the rotor in order to increase the motor torque by increasing the reluctance torque. Adding grooves uniformly distributed on the rotor and / or on the stator also makes it possible to add resolution steps on stepper motors. It is therefore desirable to propose improvements to permanent magnet synchronous motors, in order to reduce their cost, without penalizing their performance in terms of torque generated, electrical consumption, heat released and noise generated. Summary of the invention Embodiments relate to an electromechanical actuator for actuating a blackout device such as a roller shutter or a blind, comprising a casing, a head intended to be fixed to a fixed structure, a permanent magnet synchronous type motor, a speed reducer and a motor control unit, the motor, the speed reducer and the control unit being inserted into the casing of the electromechanical actuator, the motor comprising: a cylindrical rotor, permanent magnets associated with the rotor and forming magnetic poles, a cylindrical stator, arranged coaxially around the rotor and comprising a plurality of teeth extending radially towards the rotor, and a winding forming a winding around each of the teeth of the stator.According to one embodiment, the stator has an external diameter of less than 55 mm, the rotor comprises recesses around a longitudinal axis of the rotor, and the permanent magnets are inserted into the recesses of the rotor. The actuator thus defined is particularly compact and inexpensive, while offering performance suited in particular to roller shutter control applications. In particular, these arrangements make it possible to reduce the volume of the magnets without significantly affecting the performance of the motor. The recesses form flow barriers. According to one embodiment, the rotor comprises four magnetic poles each comprising one of the permanent magnets. According to one embodiment, the stator comprises six teeth. The motor diameter can be reduced by choosing a reduced number of magnetic poles and windings, without affecting the motor's performance in terms of torque, power consumption and heat emission. The 6 windings / 4 magnetic poles pair offers interesting performance in the field of application of blinds and roller shutters, with a particularly compact. According to one embodiment, the rotor comprises a first rotor groove extending on a cylindrical face of the rotor opposite each of the permanent magnets, the first rotor groove being centered on a line located outside a first longitudinal plane of the rotor and median plane of the permanent magnet. By modifying the air gap permeance of the motor, this first groove makes it possible to attenuate a disturbing peak in the noise spectrum emitted by the motor, without significantly affecting the motor's performance. According to one embodiment, the rotor comprises a second rotor groove extending on a cylindrical face of the rotor opposite each of the permanent magnets. This second groove also modifies the air gap permeance of the motor and therefore can also modify the noise spectrum. According to one embodiment, the first and second rotor grooves are arranged symmetrically with respect to the first longitudinal plane. This second groove makes it possible to symmetrize the behavior of the motor in both directions of rotation and thus to obtain an identical result regardless of the direction of rotation of the motor. Thanks to this arrangement, the symmetry of behavior of the motor in terms of noise and performance can be adapted to the operation of the actuator for the winding or unwinding of a mobile screen, regardless of the mounting direction of the actuator. According to one embodiment, the first or second rotor groove or each of the first and second rotor grooves has at least one of the following characteristics: an angular position relative to the first longitudinal plane of between 0 and 35°, a semi-circular section, and a semi-circular section having a radius of between 0.4 and 1.8 mm. According to one embodiment, each tooth of the stator comprises a stator groove formed in a free end of the tooth. This arrangement, in combination or not with one or two grooves on the rotor, also makes it possible to reduce the audible noise peak emitted by the motor, without significantly affecting the motor's performance. According to one embodiment, the stator groove formed in each tooth of the stator has at least one of the following characteristics: it is centered in a longitudinal plane of the stator and median of the tooth, it has a width of 0.2 to 3 mm, and it has a depth of 0.2 to 6 mm. The centered position of the grooves in the stator teeth further reduces the audible noise peak emitted by the motor. According to one embodiment, the permanent magnets have a parallel shape- piped, and / or are made of ferrite or plasto-ferrite. Magnets with this shape are particularly inexpensive. The use of plastoferrite can further reduce the cost of the motor without reducing its performance, especially if the entire volume of the recesses is filled with this material. According to one embodiment, the control unit applies a sinusoidal or trapezoidal command to the motor. Engine performance can be achieved by either of these control types. According to one embodiment, the rotor and / or the stator are formed by an assembly of sheet metal plates. This manufacturing technique is particularly inexpensive and fast. In addition, it allows the rotor or stator length to be easily modified depending on the desired performance, particularly the torque to be provided by the motor. In addition, this technique simplifies the production of grooves, which can be obtained by forming notches in the sheet metal plates. According to one embodiment, the motor has a power less than or equal to 300 W. The above engine characteristics are particularly suitable for engines in this power range. Embodiments may also relate to a blackout device of the roller shutter or blind type, comprising an actuator as previously defined. Brief description of the figures The present invention will be better understood with the aid of the following description with reference to the appended figures, in which identical reference signs correspond to structurally and / or functionally identical or similar elements. [Fig.1] Figure 1 is a schematic perspective and longitudinal sectional view of a permanent magnet synchronous motor, according to one embodiment, [Fig.2] Figure 2 is a schematic cross-sectional view of the permanent magnet synchronous motor, according to one embodiment, [Fig.3] Figure 3 is a schematic side view of a rotor of the permanent magnet synchronous motor, according to one embodiment, |Fig.4] Figure 4 is a schematic cross-sectional view of the rotor, according to one embodiment, [Fig.5] Figure 5 is a schematic top view of a rotor plate, according to one embodiment, [Fig.6] Figure 6 is a schematic top view of a rotor plate, according to another embodiment, [Fig.7] Figure 7 is a schematic top view of a rotor plate, according to another embodiment, [Fig.8] Figures 8, SA are schematic cross-sectional views of a permanent magnet synchronous motor, according to one embodiment, Figure 8A being an enlarged view of a portion of Figure 8, [Fig.9] Figure 9 is a schematic cross-sectional view of an actuator, according to one embodiment, [Fig.10] Figure 10 is a schematic perspective view of a home automation installation, according to one embodiment. Detailed description Figures 1 and 2 show a permanent magnet synchronous motor 1a, according to one embodiment. The motor 1a comprises a stator 2, a rotor 3 and a shaft 1A secured to the rotor, these three elements being coaxial and housed in a casing 6. The casing 6 is secured to the stator 2 and connected to the shaft 4 by means of bearings 5, for example of the ball bearing type. In Figure 2, the stator 2 has a hollow cylindrical shape 20 and comprises teeth 21 extending radially towards the inside of the cylindrical part 20. The teeth are designed to each receive a winding 11. The teeth 21 may each have a free end extended by a tile-shaped plate 23. According to one embodiment, the rotor 3 is of the inserted permanent magnet type. Thus, the rotor 3 has an external contour of cylindrical shape, inside which recesses 31 are formed forming flux barriers, the recesses being distributed around the axis of the rotor. The rotor also has a central bore 36 in which the shaft 4 is fixed, driven in rotation by the rotation of the rotor 3. Permanent magnets 12 are inserted in the recesses. The curved plates 23 at the end of the teeth 21 match the cylindrical shape of the rotor 3 while maintaining a substantially constant air gap in the facing region between each plate 23 and the external contour of the rotor 3. In the example of Figure 2, the stator 2 comprises six teeth 21 and the rotor 3 comprises four magnetic poles formed by the magnets 12. The magnets 12 have a parallelepiped shape. To limit costs, the magnets can be made, not from a rare earth, but from ferrite or plastoferrite. The magnets 12 can thus be inserted into the recesses 31 either because the section of the solid magnets corresponds substantially to that of a part of the recesses, or in the form of plastoferrite paste which then fills the recesses during manufacturing. engine building. The axial length of the magnets 12 can be greater than that of the stator so as to be able to capture the flux of the magnets by Hall effect sensors which give the position of the rotor necessary for controlling the motor 1a. The stator 2 has an external diameter less than 55 mm, for example between 35 and 55 mm. It may have a length between 14 and 20 mm. The rotor 3 may have a diameter between 18 and 25 mm and a length between 18 and 25 mm. The air gap may be between 0.2 and 0.6 mm, for example equal to 0.3 mm. The winding forming the windings 11 around the teeth 21 can be of the dental or concentric type and distributed, single or double layer. The winding can be made with 0.12 to 0.2 mm copper wire to form between 700 and 1000 turns around the teeth 21. The stator 2 and the rotor 3 can be made by a stack of a plurality of plates cut from a thin sheet metal, for example between 0.3 and 0.7 mm. The plates can be assembled by staples, in particular so as to ensure their alignment. Thus, Figure 3 shows the rotor 3 formed from a stack of two kinds of plates 33, 34, the plates 34 forming magnetic shunts. In the example of Figure 3, the rotor 3 is formed from 40 plates 33, 34, including three plates 34, then a group of sixteen plates 33 and a group of nineteen plates 33, separated by a plate 34, and finally a plate 34. Figures 2 and 4 show the shape of the plates 34. According to one embodiment, the magnets 12 are parallelepipedal in shape. Thus, the recesses 31 forming the flux barriers and housing the permanent magnets 12 can be defined by the following parameters: the radius RE of a circle centered on the longitudinal axis of the rotor 3 beyond which the recesses 31 are formed, the length ML and the width MW of the magnets 12, the half-angle Aa of extension of the recesses 31 around the longitudinal axis of the rotor 3, and the opening angle Ga of the recesses 31 on the edge of the rotor, around the longitudinal axis of the rotor. Figure 5 shows the shape of the plates 33. The plates 33 differ from the plates 34 in that the recesses 31 extend to the edge of the plates, dividing each plate 33 into a central portion 33a and peripheral portions 33b delimiting with the plate portion 33a, the outline of the recesses 31. According to an exemplary embodiment, the stator 2 may have an outer diameter of 40.7 mm, an inner diameter of 21.8 mm and a length of 15 mm. The rotor 3 may have a diameter of 21.2 mm and a length of 20 mm. Under these conditions, the parameters RE, ML, MW, Ga, Aa can take the values ​​gathered in the following table 1: [Tables 1] RE ML MW Ga Aa Magnet volume | (mm) (mm) (mm) (®) ©) (mm) 5.65 7.3 2.85 12.4 84.45 414 The motor with less expensive inserted magnets allows for slightly degraded performance compared to a reference motor of the same type, with the same dimensions, but with plated or glued permanent magnets. These performances are compared in the following table 2: [Tables 2] Inverter current |Phase current … |RMS current density (mA) rms (mA) (A / mm?) Motor la 320 183 9.1 [Reference motor |275 160 8.00 These values ​​are obtained with windings of 715 turns of wire of 0.15 mm diameter, and plates 33, 34 of 0.5 mm thickness, a sinusoidal control being applied to the motor 1a, the average torque obtained on the shaft of the motor 1a being 55 mN.m. The current density being higher, the motor 1a heats up more quickly than the reference motor. The values ​​in table 2 are very little modified if a trapezoidal control is applied to the motors. However, acoustically, both the 1a motor and the reference motor have a noise spectrum including a peak at about 2 kHz, which is within the spectrum audible to the human ear. However, the predominance of a noise peak at this frequency is annoying to the human ear, with a perception of a high-pitched noise. Figure 6 shows a plate 34' of a rotor 3' of a motor 1b, according to one embodiment. The motor 1b differs from the motor 1a only by its rotor 3'. The rotor 3' of the motor 1b differs from the rotor 3 in that the plates 33°, 34' have notches 35 distributed on their edge. The notches 35 can be defined for example by their angular position Na and their radius NR. The angular position Na is defined relative to a median plane 10 of the recesses 31, including the longitudinal axis of the rotor 3°. Once stacked and assembled, the notches 35 on the edge of the plates 33', 34” form grooves extending longitudinally along the rotor 3'. According to one embodiment, the angular position Na of the notches 35 is included between 0 and 35°, and the radius NR of the notches 35 is between 0.4 and 1.8 mm. When the notches 35 have an angular position Na at 20° and a radius NR at 0.7 mm, it can be observed that the audible noise peak is attenuated by 24 dBA, whether the engine lb is empty or loaded, compared to the engine la without notches. Figure 7 illustrates a motor Ic according to another embodiment. The motor lc differs from the motor 1b only by its 3" rotor. The 3" rotor shown in Figure 7 differs from the rotor 3' in that the 33”, 34° plates are replaced by 33", 34" plates. The 33", 34" plates differ from the 33°, 34' plates in that they each comprise a second notch 35' arranged symmetrically to the notch 35 with respect to the median plane 10 of each of the recesses 31. This arrangement does not significantly change the amplitude of the audible noise peak, but has the advantage of symmetrizing the behavior of the motor 1b according to the two directions of rotation of the latter, particularly in terms of noise. Figures 8, 8A illustrate a motor 1d according to another embodiment. The motor 1d is equipped with the rotor 3' with the plates 33', 34" with one notch 35 per pole and a stator 2". The stator 2' differs from the stator 2 in that it includes a notch 25 per tooth 21 in each plate forming the stator. Each tooth 21 of each plate forming the stator 2' includes one of the notches 25. Each notch 25 extends from the free end of one of the teeth 21 and is centered on the latter. Thus, the notches 25 form grooves extending longitudinally in the teeth 21 of the stator 2°. In Figure 8A, each of the notches 25 is defined by its width SW and its depth SD in one of the teeth 21. According to one embodiment, the notches 25 have a width SW of 0.2 to 3 mm and a depth SD of 0.2 to 6 mm. By combining the 35 notches with an angular position Na at 25° and a radius NR at 1.25 mm, and the 25 notches with a width SW of 0.5 mm and a depth SD of 1 mm, the audible noise peak is attenuated by 15 dBA, whether the motor is no-load or under load, compared to motor 1 without notches. The performances of engines 1a, 1c and 1d are compared in the following table 3: [Tables3] | Engine the lc yes Effective inverter current Effective phase current Current density | (mA) (mA) (A / mm?) 320 183 9.1 333 192 9.5 These values ​​are obtained with windings of 715 turns, and plates 33, 34 and 33", 34” of 0.5 mm thickness, a sinusoidal or trapezoidal control being applied to the motor, the average torque obtained on the motor shaft being 55 mN.m. Figure 9 shows an electromechanical actuator 50 according to one embodiment. The actuator 50 comprises a motor 56 which may be one of the motors 1a, 1b, 1c, 1d previously described, a speed reducer 57 coupled to an output shaft of the motor, and a control unit 55 connected to the motor 56, in particular to supply and control the latter with electrical energy according to control orders. The speed reducer 57 comprises an output shaft 58 forming an output shaft of the actuator 50. The motor 56, the speed reducer 57, the output shaft 58 and the control unit 55 can be housed coaxially around an axis X in a cylindrical casing 52 having an internal diameter corresponding to the external diameter of the stator of the motor 56. The speed reducer 57 can comprise an epicyclic type reducer and / or a mechanical or electromagnetic brake. Thus, the actuator 50 can be arranged for example in a winding tube 60 of a concealment device such as a roller shutter or a blind. For this purpose, the output shaft 58 of the actuator 50 is coupled by a mechanical connection 59 to the winding tube 60. Furthermore, a head 54 of the actuator 50 is fixed to a fixed structure 61. The actuator 50 also comprises a bearing crown 63 mounted on the casing 52 and free to rotate relative to the latter. The bearing crown 63 is rotatably fixed to the winding tube 60, so that the bearing crown 63 provides a rotational bearing function for the winding tube 60 on the casing 52 and / or on the head 54, on the side of the control unit 55, the output shaft 58 providing on the other side the mechanical coupling between the actuator and the winding tube 60 by the mechanical connection 59. The electromechanical actuator 50 is supplied with electrical energy by a power supply network of the building, for example by the AC mains network or by a direct current bus, or by means of a battery not shown, which can be recharged, for example, by a photovoltaic panel. Here, the electromechanical actuator 11 comprises an electrical power supply cable 62 connected to a power supply network of the mains. Figure 10 shows a home automation installation according to one embodiment. The home automation installation can be installed in a building comprising an opening, window or door, equipped with a screen 72 belonging to a blackout device 70, in particular a motorized roller blind. The blackout device 70 can alternatively be a roller shutter, a blind with adjustable slats, or even a roller door. In practice, the present invention applies to all types of blackout device comprising a rotating motorized winding shaft. The screen 72 of the occulting device 70 is wound on a winding tube such as the winding tube 60 driven by the electromechanical actuator 50. The screen 72 is movable between a wound position, in particular high, and an unwound position, in particular low. In a known manner, the screen 72 of the occultation device 70 is formed by a canvas, which is attached by a first end to the winding tube and by the other end to a weighted bar 73. The upper wound position of the screen corresponds to the position of the weighted bar at the winding tube 60 and the lower unwound position corresponds to the position of the weighted bar 73 of the screen 72 at the threshold of the opening. The deployment of the screen 72 can be guided by slides 71. The winding tube 60 can be arranged inside a box 74 or be visible. The winding tube 60 is movable in rotation relative to a support, such as a cheek, of the box 74. It will be clear to those skilled in the art that the present invention is susceptible to various variant embodiments and various applications. In particular, the invention is not limited to actuators for shutters and blinds. It applies more generally to cylindrical actuators having a power less than or equal to 300 W. Furthermore, the number of magnetic poles of the rotor and the number of teeth of the stator can take other values, without departing from the scope of this description. If the motor is controlled by three phases, it is simply important that the number of teeth of the stator is a multiple of 3. The permanent magnets are not necessarily parallelepipedal in shape, but could take any other shape adapted to the shape of the recesses 31. Thus, the magnets can fill the entire volume of the recesses, up to the external surface of the rotor. The magnets and the empty volumes delimited by the recesses can be tile-shaped. The angles Na of the notches 35, 35' are not necessarily identical from one 33°, 33", 34°, 34" plate to another, so that the grooves formed by the notches 35, 35' are not necessarily parallel to the rotor axis, or even straight. Furthermore, not all 33°, 33", 34°, 34" plates are necessarily provided with notches 35 and / or 35”, so that the grooves on the rotor may be discontinuous or not extend over the entire length of the rotor. Thus, for example, only the 33°, 33" plates could be provided with notches 35, 35°. The grooves formed by the notches are not necessarily symmetrical with respect to the longitudinal planes of the rotor and the median planes of the permanent magnets. Indeed, it may not be necessary to symmetrize the behavior of the motor in both directions of rotation, especially in applications where the motor is only used in one direction of rotation. The grooves 25 formed in the 2” stator are not necessarily centered on the teeth 21. Indeed, an off-center position of the grooves 25 makes it possible to reduce the audible noise peak of the motor. Furthermore, the motor may include these stator grooves without grooves on the rotor. Indeed, such an arrangement also makes it possible to reduce the audible noise peak. The rotor and / or stator are not necessarily made from an assembly of sheet metal plates. In fact, each of these motor elements can be formed from a single piece, for example metal, obtained by machining or additive manufacturing (3D printing).

Claims

Demands

1. Electromechanical actuator for actuation of a device blackout devices such as roller shutters or blinds, including a casing (52), a head (54) intended to be fixed to a fixed structure (61), a permanent magnet synchronous motor (la, lb, lc, 1d, 56), a speed reducer (57) and a motor control unit (55), the motor (la, 1b, lc, 1d, 56), the speed reducer (57) and the unit of control (55) being inserted into the housing (52) of the electro- actuator mechanical, the engine comprising: a cylindrical rotor (3, 3', 3"), permanent magnets (12) associated with the rotor and forming ma- poles genetics, a cylindrical stator (2, 2') arranged coaxially around the rotor and comprising a plurality of teeth (21) extending ra- dialy towards the rotor, and a winding (11) forming a coil around each of the teeth of the stator. characterized in that: the stator (2, 2') has an external diameter of less than 55 mm, the rotor (3, 3', 3") includes recesses (31) around a longitudinal axis gitudinal of the rotor, and The permanent magnets are inserted into the recesses of the rotor.

2. Actuator according to claim 1, wherein the rotor (3, 3', 3") comprises four magnetic poles, each containing one of the magnets permanents (12).

3. Actuator according to claim 1 or 2, wherein the stator (2, 2') includes six teeth.

4. Actuator according to any one of claims ! to 3, wherein the rotor (3°, 3") includes a first rotor groove (35) extending over one face cylindrical of the rotor opposite each of the permanent magnets (12), the first rotor groove being centered on a line located outside of a first longitudinal plane of the rotor and median of the magnet permanent.

5. Actuator according to claim 4, wherein the rotor (3") comprises a second rotor groove (35') extending over a cylindrical face of the rotor opposite each of the permanent magnets (12).

6. Actuator according to claim 5, wherein the first and second rotor grooves (35, 35') are arranged symmetrically by relative to the first longitudinal plane.

7. Actuator according to claim 5 or 6, wherein the first or the second rotor groove (35, 35”) or each of the first and second the rotor groove has at least one of the following characteristics: an angular position (Na) relative to the first longitudinal plane between 0 and 35°, a semi-circular section, and a semi-circular section having a radius (NR) between 0.4 and 18 mm.

8. Actuator according to any one of claims 7, wherein each tooth 21) of the stator (2°) includes a stator groove (25) formed in a free end of the tooth.

9. Actuator according to claim 8, wherein the stator groove (25) formed in each tooth (21) of the stator (2') has at least one of the The following characteristics: It is centered in a longitudinal plane of the stator and median to the tooth. It has a width (SW) of 0.2 to 3 mm, and It has a depth (SD) of 0.2 to 6 mm.

10. An actuator according to any one of claims 1 to 9, wherein the magnets permanent structures have a parallelepiped shape, and / or are made in ferrite or plasto-ferrite.

11. Actuator according to claim 10, wherein the control unit (55) applies a sinusoidal or trapezoidal control to the motor.

12. Actuator according to any one of claims 1 to 11, wherein the rotor (3, 3', 3") and / or the stator (2, 2') are formed by an assembly of plates sheet metal.

13. Actuator according to any one of claims 1 to 12, wherein the motor (a, 1b, lc, 1d, 56) has a power rating of 300 W or less.

14. | A roller shutter or blind type blackout device, comprising a actuator according to any one of claims 1 to 13.