Electromechanical actuator comprising a compact and low-noise synchronous reluctance motor

Abstract

The invention relates to an electromechanical actuator for actuating a screening device such as a roller shutter or a blind, comprising a housing, a head intended to be fixed to a fixed structure, a synchronous type motor, a speed reducer and a motor control unit, the motor, the speed reducer and the control unit being inserted into the housing of the electromechanical actuator, the motor comprising a cylindrically shaped rotor, a cylindrically shaped stator, arranged coaxially around the rotor and having a plurality of teeth extending radially towards the rotor, and a winding which winds around each of the teeth of the stator; the stator has an outside diameter of less than 55 mm, the rotor is formed by an assembly of sheet metal plates and comprises cutouts around a longitudinal axis of the rotor, the rotor comprising an arrangement of the cutouts forming four poles, the rotor comprising two or three cutouts per pole.

Description

[0001] DESCRIPTION

[0002] TITLE :

[0003] ELECTROMECHANICAL ACTUATOR COMPRISING A MOTOR

[0004] COMPACT AND LOW-NOISE SYNCHRONOUS RELUCTANCE

[0005] Technical field

[0006] The present invention relates to the field of electric motors and more particularly to synchronous “brushless” electric motors in the power ranges 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 rotate a winding shaft or tube to drive a roller shutter or a blind to conceal a window or door of a building.

[0007] State of the art

[0008] A "brushless" synchronous electric motor typically comprises a rotor and a stator with several windings. In applications where the motor is fitted to an electromechanical actuator rotating a winding tube, it is desirable for reasons of space to house the actuator in the winding tube, which imposes significant constraints on the actuator in terms of volume and thermal properties. Indeed, the motor itself is encapsulated in a casing, generally metallic, of the actuator. The diameter of the motor is therefore limited to a few centimeters. Under these conditions, it is difficult to ventilate the motor. Furthermore, the actuator can also be subjected to high temperatures when mounted in the winding tube of a roller shutter or blind mounted on the facade of a building. The length of the motor is also reduced as much as possible to allow an actuator length suitable for the greatest number of applications.

[0009] In the field of "brushless" synchronous electric motors, the synchroreluctant motor is increasingly popular, due to its performance, particularly in terms of power density and noise, compared to other motors such as cage asynchronous motors. The synchroreluctant motor can be powered by a sinusoidal or trapezoidal signal. It also most often includes Hall effect sensors for detecting the position of the rotor relative to the stator.

[0010] A major advantage of synchronous motors is that they can operate without magnets. This feature helps limit production costs and overcome potential magnet supply difficulties. However, the main challenge is the production of the rotor, which has a particularly small diameter.

[0011] On the other hand, by reducing the size of the motors, resonance phenomena appear between the electromagnetic forces occurring within the motor and the mechanical elements of the latter. These resonance phenomena correspond to a noise spectrum which can include peaks in the audible frequency range which prove annoying for humans.

[0012] It is therefore desirable to propose improvements to synchroreluctant type motors, in order to adapt their manufacture, without penalizing their performance in terms of torque generated, electrical consumption, heat released and noise generated.

[0013] Summary of the invention

[0014] 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 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, 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, characterized in that: the stator has an external diameter of less than 55 mm, the rotor is formed by an assembly of sheet metal plates, the rotor comprises recesses around a longitudinal axis of the rotor,the rotor comprising an arrangement of recesses forming four poles, the rotor comprising two or three recesses per pole.,

[0015] The motor actuator thus defined is particularly compact and inexpensive, while offering performances adapted in particular to roller shutter control applications for low torques. In particular, this rotor manufacturing technique proves to be particularly inexpensive and fast. In addition, it allows the length of the motor to be easily modified according to the desired performances, in particular the torque to be provided by the motor. The impact of the number of recesses on the torque value that the motor can provide must be counterbalanced by the technical feasibility of producing these housings in the space requirement of a rotor section and the mechanical strength of the rotor. Thus, an optimal number of recesses per pole is equal to two or three.

[0016] According to one embodiment, the stator comprises six teeth.

[0017] 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 stator.

[0018] According to one embodiment, the rotor comprises a first rotor groove extending on a cylindrical face of the rotor opposite each of the poles, the first rotor groove being centered on a line located outside a first median plane of the pole passing through the longitudinal axis of the rotor.

[0019] By modifying the motor's air gap permeance, this first groove helps to attenuate a disturbing peak in the noise spectrum emitted by the motor, without significantly affecting the motor's performance.

[0020] According to one embodiment, the rotor comprises a second rotor groove extending on a cylindrical face of the rotor opposite each of the poles.

[0021] This second groove also modifies the air gap permeance of the motor and therefore can also modify the noise spectrum.

[0022] According to one embodiment, the first and second rotor grooves are arranged symmetrically with respect to the first plane.

[0023] 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.

[0024] 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 about the longitudinal axis of the rotor relative to the first 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.

[0025] This arrangement, in combination or not with one or two grooves on the rotor, also helps to reduce the audible noise peak emitted by the motor, without significantly affecting the motor's performance.

[0026] 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 on a median plane of the tooth passing through a longitudinal axis of the stator, it has a width of 0.2 to 3 mm, and it has a depth of 0.2 to 6 mm.

[0027] The centered position of the grooves in the stator teeth further reduces the audible noise peak emitted by the motor.

[0028] According to one embodiment, the actuator is powered by the AC mains network.

[0029] According to one embodiment, the control unit applies a sinusoidal or trapezoidal command to the motor.

[0030] Engine performance can be achieved by either of these control types.

[0031] According to one embodiment, the stator is formed by an assembly of sheet metal plates.

[0032] This manufacturing technique is particularly inexpensive and quick. Furthermore, it allows the 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.

[0033] According to one embodiment, the motor has a power less than or equal to 300 W.

[0034] The above engine characteristics are particularly suitable for engines in this power range.

[0035] According to one embodiment, the thickness of the sheets forming the rotor is between 0.3 and 0.7 mm, preferably 0.5 mm.

[0036] 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

[0037] 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.

[0038] Figure 1 is a schematic perspective and longitudinal sectional view of a synchroreluctant motor, according to one embodiment,

[0039] Figure 2 is a schematic cross-sectional view of the synchroreluctant motor, according to one embodiment,

[0040] Figure 3 is a schematic side view of a rotor of the synchroreluctant motor, according to one embodiment,

[0041] Figure 4 is a schematic cross-sectional view of the rotor, according to one embodiment,

[0042] Figure 5 is a schematic top view of a rotor plate, according to one embodiment,

[0043] Figure 6 is a schematic top view of a rotor plate, according to another embodiment,

[0044] Figure 7 is a schematic top view of a rotor plate, according to another embodiment,

[0045] Figures 8, 8A are schematic cross-sectional views of a synchroreluctant motor, according to one embodiment, Figure 8A being an enlarged view of a portion of Figure 8,

[0046] Figure 9 is a schematic cross-sectional view of the rotor, according to another embodiment,

[0047] Figure 10 is a schematic cross-sectional view of the rotor, according to another embodiment,

[0048] Figure 11 is a schematic cross-sectional view of an actuator, according to one embodiment,

[0049] Figure 12 is a schematic perspective view of a home automation installation, according to one embodiment.

[0050] Detailed description

[0051] Figures 1 and 2 represent a motor 1a of the synchroreluctant type, according to one embodiment. The motor 1a comprises a stator 2, a rotor 3 and a shaft 4 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.

[0052] 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.

[0053] According to one embodiment, the rotor 3 is of the transverse lamination type, otherwise called flux barrier type, without magnets. Thus, the rotor 3 has an external contour of cylindrical shape, inside which are formed recesses 31 a, 31 b forming flux barriers. The recesses 31 a, 31 b are distributed around a longitudinal axis X of the rotor and grouped in pairs of recesses centered on a longitudinal plane of the rotor 3. Each pair of recesses 31 a, 31 , comprises a recess 31 a further from the longitudinal axis X of the rotor 3 and a recess closer to this axis. 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. The symmetrical geometric arrangement of the different recesses, therefore of the different flux barriers around the longitudinal axis X of the rotor, creates poles of the rotor, for example four poles.The curved plates 23 at the end of the teeth 21 of the stator 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.

[0054] In the example of Figure 2, the stator 2 comprises six teeth 21 and the rotor 3 comprises four poles formed by the arrangement of the recesses.

[0055] The axial length of the rotor 3 may be greater than that of the stator so as to be able to capture the magnetic flux created by the arrangement of the rotor recesses by Hall effect sensors which give the position of the rotor necessary for controlling the motor 1a.

[0056] 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.

[0057] The winding forming the windings 11 around the teeth 21 may be of the dental or concentric type and distributed, single or double layer. The winding may be made with copper wire of 0.12 to 0.2 mm to form between 700 and 1000 turns around the teeth 21. The stator 2 and the rotor 3 may 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 may be assembled by staples, in particular so as to ensure their alignment. Thus, Figure 3 represents 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 of 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.

[0058] Figures 2 and 4 show the shape of the plates 34 for a rotor with two recesses forming the flux barriers per pole. The recesses 31 a, 31 b forming the flux barriers are substantially an assembly of straight segments. For example, as shown in Figures 4 and 5, the section of a recess may take a rectangular shape at the median level of the pole, extended on either side of the short side by substantially trapezoidal extensions.

[0059] The recesses in straight segments can be defined by the following parameters: the radius RE of a circle centered on the longitudinal axis X of the rotor 3 beyond which the recesses 31a, 31b are formed, the width BW of a central segment of the recesses 31a, 31b, the half-angles Aa, Ab around the longitudinal axis X of the rotor 3, of extension of each of the recesses 31a, 31b, and the opening angle Ga around the longitudinal axis X of the rotor of each of the recesses 31a, 31b on the edge of the rotor.

[0060] According to an alternative embodiment shown in Figure 9, the recesses 31 a', 31 b' forming the flow barriers have a section substantially in the form of a portion of a ring and can be defined by the following parameters: the radius Rba of the bottom of the first recess 31 a, closest to the edge of the rotor, the radius Rbb of the bottom of the second recess 31 b, closest

[0061] The median radius Rfer between the first and second recesses 31 a, 31 b,

[0062] The width LB of a recess, this width can be common for all the recesses.

[0063] Other flow barrier geometries may be envisaged without departing from the scope of the present invention.

[0064] According to the embodiment with two recesses per pole, the recesses 31 a, 31 b extend in pairs along a radius of the rotor 3 and are distant from each other and from the longitudinal axis X of the rotor. According to an alternative embodiment shown in FIG. 10, a rotor 300 comprises three recesses 131 a, 131 b, 131 c per pole, a third recess 131 c extends transversely to a radius of the rotor 3 and is distant from the recesses 131 a, 131 b, 131 c along a radial direction of the rotor 300.

[0065] Figure 5 shows the shape of the plates 33. The plates 33 differ from the plates 34 in that the recesses 31a, 31b are through, that is to say extend to the edge of the plates forming the cylindrical face of the rotor, dividing each plate 33 into a central part 33a, intermediate parts 33b and peripheral parts 33c. The parts 33b and 33c delimit with the central part 33a, the outline of the recesses 31a and 31b. In the assembled construction of the rotor, the recesses 31 a, 31 b form freely open through spaces on the cylindrical outer wall of the rotor 3. In the arrangement of the plates 33, 34 shown in Figure 3, the recesses 31 a and 31 b extend over only one or more parts of the length (along the longitudinal axis X) of the rotor 3.

[0066] 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.

[0067] Preferably, the iron lengths Lfer and air gap are set at Lfer = 15mm and e = 0.3mm, corresponding to the conventional dimensions in applications of electromechanical actuators for the actuation of blinds or roller shutters. Under these conditions, the parameters Rb1, Rb2, Rfer and Lb of the rotor can take the values ​​gathered in the following table 1:

[0068] Table 1

[0069] 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 between 32 and 35 mN. m.

[0070] Torque performance can be improved by reducing the impact of magnetic shunts, particularly by reducing the thickness of the laminations 34.

[0071] Similarly, the presence of two recesses forming flux barriers per pole makes it possible to limit torque ripples compared to a structure with a single recess forming a flux barrier per pole. However, acoustically, the motor 1a has a noise spectrum including a peak at approximately 2 kHz which is within the spectrum audible to the human ear. However, the predominance of a noise peak at this frequency proves annoying to the human ear, with a perception of a high-pitched noise.

[0072] 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 31a, 31b, including the longitudinal axis X 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'.

[0073] According to one embodiment, the angular position Na of the notches 35 is 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 motor 1b is empty or loaded, compared to the motor 1a without notches.

[0074] Figure 7 illustrates a motor 1c according to another embodiment. The motor 1c 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 plates 33', 34' are replaced by 33", 34" plates. The 33", 34" plates differ from the plates 33', 34' 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 31a, 31b. 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, in particular in terms of noise.

[0075] 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 a notch 35 per pole and a stator 2'. The stator 2' differs from the stator 2 in that it comprises a notch 25 per tooth 21 in each plate forming the stator. Each tooth 21 of each plate forming the stator 2' comprises 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.

[0076] 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 the motor 1 without notches.

[0077] Figure 11 represents 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 A 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.

[0078] 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 54 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.

[0079] 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.

[0080] Figure 12 represents 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] Furthermore, the number of rotor poles and the number of stator teeth 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 stator teeth is a multiple of 3.

[0085] The angles Na of the notches 35, 35' are not necessarily identical from one plate 33', 33", 34', 34" to another, so that the grooves formed by the notches 35, 35' are not necessarily parallel to the X axis of the rotor, or even rectilinear. Furthermore, not all the plates 33', 33", 34', 34" 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 plates 33', 33" could be provided with notches 35, 35'.

[0086] The grooves formed by the notches are not necessarily symmetrical with respect to the mid-planes of the poles and passing through the longitudinal axis X of the rotor. 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 used in only one direction of rotation.

[0087] The grooves 25 formed in the stator 2' 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 comprise these stator grooves without grooves on the rotor. Indeed, such an arrangement also makes it possible to reduce the audible noise peak.

Claims

DEMANDS 1. Electromechanical actuator for actuation of a shading device such as a roller shutter or blind, comprising a housing (52), a head (54) for attachment to a fixed structure (61), a synchronous motor (1a, 1b, 1c, 1d, 56), a speed reducer (57), and a motor control unit (55), the motor (1a, 1b, 1c, 1d, 56), the speed reducer (57), and the control unit (55) being inserted into the housing (52) of the electromechanical actuator, the motor comprising: a cylindrical rotor (3, 3', 3"), a cylindrical stator (2, 2') arranged coaxially around the rotor and having a plurality of teeth (21) extending radially towards the rotor, and a winding (11) forming a winding around each of the stator teeth, characterized in that: the stator (2, 2') has an external diameter of less than 55 mm, the rotor (2, 2') is formed by an assembly of sheet metal plates, the rotor (3, 3',3") includes recesses (31 a, 31 b) around a longitudinal axis of the rotor, the rotor (3, 3', 3") comprising an arrangement of the recesses forming four poles, the rotor comprising two or three recesses (31 a, 31 b, 31 c) per pole formed around a longitudinal axis of the rotor and extending to a cylindrical face of the rotor.

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

3. Actuator according to any one of claims 1 and 2, wherein the rotor (3', 3") comprises a first rotor groove (35) extending over a cylindrical face of the rotor opposite each of the poles, the first rotor groove being centered on a line located outside a first median plane of the pole passing through the longitudinal axis of the rotor.

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

5. Actuator according to claim 4, in which the first and second rotor grooves (35, 35') are arranged symmetrically with respect to the first plane.

6. Actuator according to claim 4 or 5, wherein the first or second rotor groove (35, 35') or each of the first and second rotor grooves has at least one of the following characteristics: an angular position (Na) around the longitudinal axis of the rotor relative to the first plane, between 0 and 35°, a semi-circular section, and a semi-circular section having a radius (NR) between 0.4 and 1.8 mm.

7. Actuator according to any one of claims 1 to 6, wherein each tooth (21) of the stator (2') comprises a stator groove (25) formed in a free end of the tooth.

8. Actuator according to claim 7, wherein the stator groove (25) formed in each tooth (21) of the stator (2') has at least one of the following characteristics: it is centered in a second median plane of the tooth passing through a longitudinal axis of the stator, it has a width (SW) of 0.2 to 3 mm, and it has a depth (SD) of 0.2 to 6 mm.

9. Actuator according to any one of claims 1 to 8, wherein the actuator is powered by the AC network of the sector.

10. Actuator according to claim 9, wherein the control unit (55) applies a sinusoidal or trapezoidal control to the motor.

11. Actuator according to any one of claims 1 to 10, wherein the stator (2, 2') is formed by an assembly of sheet metal plates.

12. Actuator according to any one of claims 1 to 11, wherein the motor (1a, 1b, 1c, 1d, 56) has a power less than or equal to 300 W.

13. Actuator according to any one of claims 1 to 12, wherein the thickness of the sheets forming the rotor is between 0.3 and 0.7 mm, preferably 0.5 mm.

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

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