Electromechanical actuator for driving a closure or sunshade, closure or sunshade system with such an actuator, and method for dimensioning a compensation spring for a row of blinds, each with such an actuator.

Description

[0001] The present invention relates to an electromechanical actuator for driving a mobile closing or sun protection screen, according to the preamble of claim 1. Such an actuator is known from US 2013 / 099714 A1.

[0002] The present invention also relates to a closing or solar protection installation comprising such an actuator, according to claim 5, as well as a method for dimensioning a compensation spring for a range of blinds each incorporating such an actuator, according to claim 6.

[0003] Such actuators for closing or sun protection installations, particularly for driving interior blinds, are generally tubular in shape to be inserted into a roller tube on which the closing or sun protection screen is rolled up. They can be powered by autonomous power sources, such as rechargeable batteries or cells. The actuator must be designed to allow long-term operation, taking into account potential energy replenishment difficulties.

[0004] Roller blind installations equipped with a pre-stressed compensation spring are known in the prior art. Such installations use the compensation spring to limit the forces required to raise the blind, by increasing the pre-stress of the spring during a blind deployment movement. Such springs are used in manual installations, but also in installations motorized by an electromechanical actuator, in particular to limit the electrical energy required to move the blind over a raising-lowering cycle. They are therefore well suited for actuators whose energy source is autonomous. The compensation spring may be located in a winding tube on which the blind is wound, opposite the electromechanical actuator, or on the body of the electromechanical actuator, or at the output shaft of the electromechanical actuator.The pre-stressing must take into account in particular the number of turns that the roller tube must make between a high point and a low point of the blind, in other words between a fully rolled-up position of the blind and a fully unrolled position. At the same time, it is possible to choose a stiffness of the compensation spring to be used for a blind, in particular by taking into account the mechanical power to be supplied to the blind to move it.

[0005] However, defining a compensation spring stiffness per blind increases the cost of installations including such blinds.

[0006] Another energy source available, particularly in commercial buildings or new residential constructions, is power supply via an Ethernet network. PoE (Power over Ethernet) technology allows an Ethernet network to be used both for powering electrical loads in the building and for transmitting data, such as control signals for electrical loads.

[0007] PoE technology is based on the standard for computer networks published by the IEEE (Institute of Electrical and Electronics Engineers) under the reference 802.3: The IEEE 802.3af (PoE) standard provides a maximum power of 15W for an input voltage of 46 to 57 VDC. The IEEE 802.3at (PoE+) standard provides a maximum power of 30W for an input voltage of 52 to 57 VDC. The IEEE 802.3bt (High Power PoE) standard provides a maximum power of 100W for an input voltage of 52 to 57 VDC.

[0008] Ethernet cables suitable for transmitting power and data consist of four pairs of wires. Data is transmitted over at least two pairs of wires, namely wires numbered 1, 2, 3, and 6, while power is transmitted over at least two other pairs of wires, namely wires numbered 4, 5, 7, and 8.

[0009] In the field of actuators for closing or solar protection installations, motors powered by a power source, such as batteries, are generally brushed and collector DC motors, designed to operate at a voltage of 12V or 24V.

[0010] In the case of PoE technology, the nominal voltage is around 48V. DC motors powered directly at 48V are complex to obtain, due to the significant heating at the brushes and collectors for these voltage levels. The voltage is indeed high for the number of brushes and collectors, especially in reduced dimensions such as those of a winding tube for a closing or solar protection screen whose diameter is 60mm, 50mm or less.

[0011] Therefore, since the motor is designed to support a lower voltage than that provided by the Ethernet connection, it is necessary in an actuator powered by PoE technology to use a converter to avoid damaging the motor. However, using a converter involves additional cost and increased complexity, as well as a significant footprint that can be problematic when a compact solution is required. On the other hand, using a converter penalizes the electrical efficiency of the actuator.

[0012] It is these drawbacks that the invention more particularly intends to remedy by proposing a more compact electromechanical actuator for driving a closing or solar protection screen, having an electrical efficiency optimized compared to that of an actuator with a converter.

[0013] For this purpose, the invention relates to an electromechanical actuator for driving a mobile closing or sun protection screen, the actuator comprising a motor, a control card, a brake, a reducer and a connector for connection to a power supply source. According to the invention, the connector comprises eight electrical contacts, the connector being in particular of the RJ45 type, for powering the actuator and transmitting data from an Ethernet network, the motor is a synchronous motor comprising a wound stator and a rotor with permanent magnets, the motor being adapted to operate directly under the voltage supplied by the Ethernet network, the stator winding being designed to withstand a voltage of 36V to 57V, preferably a voltage between 46V and 57V, in particular a voltage of approximately 48V.

[0014] Thanks to the invention, the presence of a brushless permanent magnet synchronous motor, designed to operate at a voltage, for example, equal to approximately 48 V, does not require the addition of a converter. Indeed, the motor is designed to withstand the voltage of the current supplied via the Ethernet connection. This also implies a saving of space within the actuator, which is all the more important as the diameter of the actuator is small. On the other hand, the wires used for the stator winding of a permanent magnet synchronous motor have a smaller diameter than that of a motor of the same type, providing the same torque and designed to operate at 12 V or 24 V. This allows a higher filling coefficient and therefore a higher electrical efficiency of the motor. However, since the electrical power that can be supplied via PoE cables is limited, it is important to optimize the electrical efficiency of the electromechanical actuator.

[0015] According to advantageous but not mandatory aspects of the invention, such an actuator includes one or more of the following features, taken in any technically admissible combination: The maximum diameter of the actuator is less than 60 mm, in particular less than 50 mm. The actuator includes a compensation spring. The compensation spring is pre-stressed, a number of pre-stress turns being adapted to a stiffness of the compensation spring and determined to minimize a maximum electrical power to be supplied by the motor.

[0016] According to another aspect, the invention relates to a closing or solar protection installation comprising a blind equipped with a screen and an actuator as mentioned above.

[0017] According to yet another aspect, the invention relates to a method for dimensioning a compensation spring for a range of blinds of different widths and heights, each blind incorporating an actuator as described above. According to the invention, this method comprises at least the following steps. First, in a step a), the range of blinds to be equipped with compensation springs is chosen. Then, in a step b), a range of stiffnesses of compensation springs to be tested is chosen. Then, in a step c), for each stiffness of the range of m stiffnesses, the behavior of the n blinds is determined. In a step d), a single stiffness adapted to the entire range of blinds is selected from the stiffnesses of the range of m stiffnesses according to the behavior of the n blinds determined in step c).

[0018] This process induces the same advantages as those mentioned above regarding the Ethernet-powered actuator.

[0019] According to advantageous but not mandatory aspects of the invention, such a method includes one or more of the following features, taken in any technically admissible combination: step c) comprises substeps. A first substep e) consists of calculating, for a stiffness, a maximum power to be supplied by the motor over a raising and lowering cycle of the blind and storing this value in a memory for each blind in the range of blinds considered. A second substep f) consists of choosing, for each stiffness, the highest maximum electrical power to be supplied from among the maximum electrical powers calculated in substep e) and storing this value, as well as the associated stiffness, in the memory. the stiffness selected in step d) is the stiffness associated with the lowest power, chosen from the stiffnesses of step f). the maximum electrical power delivered for each blind depends on the maximum torque to be supplied in the fully unrolled position of the blind and the electrical efficiency of the motor.

[0020] The invention will be better understood and other advantages thereof will appear more clearly in the light of the following description of an embodiment of an electromechanical actuator for driving a mobile closing or sun protection screen, of a closing or sun protection installation and of a method for dimensioning a compensation spring in accordance with its principle, given solely by way of example and with reference to the drawings, in which: [ Fig 1 ] there figure 1 is a diagram of an installation in accordance with the invention incorporating an actuator, [ Fig 2 ] there figure 2 is an electronic schematic representation of an actuator according to the invention; [ Fig 3 ] there figure 3 is a diagram of a home automation network comprising an actuator according to the invention; [ Fig 4 ] there figure 4 is a diagram of a method for dimensioning a compensation spring according to the invention. Fig 5 ] there figure 5 is a cross-section of the electric motor of the actuator according to one embodiment.

[0021] A solar protection installation I, which includes an electromechanical actuator 2 intended to be powered by an Ethernet network R, is shown schematically in the figure 1 .

[0022] Installation I also includes a motorized blind as home automation equipment. The motorized blind includes in particular a screen 28 and a winding shaft 26, on which the screen 28 is wound.

[0023] The electromechanical actuator 2 is arranged at least partially in the winding shaft 26, which has the shape of a winding tube. It provides a rotational drive of the winding tube 26 by means of a connection 14, such as an output shaft. The actuator 2 comprises a housing 4, shown in dotted lines on the figure 1 , defining an X4 axis.

[0024] The casing 4 contains a control card 6, a motor 8, a brake 10 and a reducer 12 which belong to the actuator 2 and are aligned, in this order, along the axis X4 and which are connected to each other by links 14 and 16.

[0025] The connections 14 are mechanical connections between the motor 8 and the brake 10 and between the brake 10 and the reducer 12. The connection 16 is an electronic connection between the control card 6 and the motor 8.

[0026] Motor 8 is a brushless electronically commutated direct current motor, commonly referred to as a BLDC (Brushless Direct Current) motor, or more generally as a PMSM (Permanent Magnet Synchronous Motor).

[0027] We will now describe in more detail and with reference to the figures 2 And 5 the electric motor 8 of the electromechanical actuator 2. The motor 8 comprises a rotor 82 with permanent magnets and a stator 84 comprising a winding 87 formed by windings 86 electrically powered by power supply lines 65 connected to a power supply circuit 62. For example, the rotor 82 is connected, indirectly, to the winding shaft 26.

[0028] We note D3 the external diameter of the electric motor 8, this diameter being, in practice, equal to the external diameter of the stator 84.

[0029] The rotor 82 comprises a rotor body 81, provided with magnetic elements 83 surrounded by the stator 84. The magnetic elements 83 are arranged on the outer circumference of the rotor body 81. The magnetic elements 83 of the rotor 82 are permanent ferrite magnets.

[0030] The magnetic elements 83 are separated from the stator 84 by an air gap 80, radial with respect to the axis of rotation X.

[0031] The radial thickness of the magnetic elements 83 is denoted e88, which is measured in a radial direction to the X axis. This thickness e88 is chosen to be greater than 3 mm, preferably between 3.8 and 4.2 mm, which contributes to providing the electromagnetic forces necessary for the operation of the motor, contributes to the industrial feasibility of the permanent magnets and limits the risks of demagnetization thereof. The magnetic elements or permanent magnets 83 can be attached to the outer circumference of the rotor body 81 by gluing, overmolding or any other known technique.

[0032] We note respectively D5 the external diameter of the rotor 82 and D6 the external diameter of the body of the rotor 81. The diameter D5 is greater than or equal to half of the diameter D3.

[0033] The stator 84 is formed by a stator core 85 made of magnetizable material, more specifically of ferromagnetic material, which is generally formed by a stack, or packet, of laminations and provided with insulating linings. The stator core 85 comprises polar elements 88 distributed over a peripheral wall 89 of the stator core 85, preferably on the inside of the peripheral wall 89 of the stator core 85. The stator 84 is obtained from a stator core 85 comprising a stack of laminations each forming a closed circumference, on which the winding 87 is attached, and not by a set of sectors, with one or more teeth, wound which, by their assembly, form the closed circumference of the stator core 85. Indeed, the small dimensions of the electric motor 8 do not allow the stator 84 to be produced by assembling several wound angular sectors.

[0034] On the figure 5 , a single winding 87 is shown in place around a single pole member 88, for clarity of the drawing.

[0035] The polar elements 88 of the core 85 project towards the inside of the electric motor 8, from the peripheral wall 89. Advantageously, there are six of them, uniformly distributed on the peripheral wall 89, thus forming a six-pole stator 84. The space E88 formed between two adjacent polar elements 88 is called a notch. Windings 87 are positioned in the notches, around the polar elements 88 of the stator 84. More precisely, each polar element 88 is surrounded by a winding 87 of its own. These windings 87 are such that they have the same number of turns per polar element. The windings 87 of the diametrically opposite polar elements are connected at the ends of the stator core 84 to form a phase.

[0036] The winding of the motor 8 is designed to operate at a voltage of 48 volts (V). In other words, the winding formed by windings 86 of the stator 84 is adapted to withstand a voltage of 48V.

[0037] The winding 87 is made of a copper wire suitable for operating at a voltage of 48 volts. In other words, the diameter of the copper wire used to form the winding 87 of the stator 84 is suitable for operating directly at the voltage supplied by the Ethernet network.

[0038] The wire diameter used is smaller than for a motor suitable for operating under 12V or under 24V, which makes it possible to better fill the slots of the stator 84 and therefore to optimize the electrical efficiency of the motor 8.

[0039] The actuator 2 also includes a connector 18, with eight positions and eight electrical contacts, of the RJ45 type (from the English “Registered Jack”). This connector 18 is commonly called a male “RJ45 socket”. The connector 18 is connected to the control board 6 by an electronic connection 16. The connector 18 can be fixed, as shown in the figure 1 , at the end of a cable coming out of the actuator 2. It is intended to be connected to a complementary connector 19, commonly called a “female RJ45 socket” adapted to supply the motor 8, from the Ethernet network R which also belongs to the installation I, a current having a voltage of approximately 48V for which the motor 8 is particularly suitable. There is therefore no need to add a converter between the connector 18 and the motor 8. This makes it possible to obtain a compact, economical and reliable actuator 2, with optimal electrical efficiency.

[0040] Furthermore, a torque support 20, commonly called the “actuator head” is arranged at one end of the casing 4, for fixing the actuator 2, for example, to a partition wall (not shown). According to a variant of the invention (not shown), the connector 18 can also be integrated at the torque support 20 of the actuator 2.

[0041] The actuator 2 also comprises a wheel 22, rotatable relative to the torque support 20 and to the casing 4 of the actuator 2 and fixed in rotation in the winding shaft 26 and on the output shaft 14. The wheel 22 allows the winding shaft 26 to be driven in rotation by the output shaft 14 of the actuator 2, for raising or lowering the screen 28 of the blind. The actuator 2 comprises a crown 23, also free to rotate relative to the torque support 20 and to the casing 4 of the actuator 2 and fixed in rotation in the winding shaft 26. The crown 23 forms a bearing for supporting in rotation one end of the winding shaft 26 on the casing 4 of the actuator 2. To facilitate reading of the drawings, the winding tube 26 and the screen 28 are shown in dotted lines on the figure 1 The screen 28 makes it possible to selectively obscure, in whole or in part, an opening O, such as a window. The blind is formed of the elements 26 and 28.

[0042] In the example of the figures, the screen 28 is a fabric canvas. Alternatively, it may be an assembly of slats.

[0043] In operation, the instantaneous power that the Ethernet network can provide is limited, in particular by the 802.3af (PoE) and 802.3at (PoE+) standards which are the most commonly used.

[0044] There figure 3 shows a communication network N, such as a hierarchical network with several hierarchy levels or ranks. The communication network N comprises a main network B, which notably comprises a common data bus 30, forming a physical backbone link, also called a "backbone" in English, to which a control unit 32 is connected. For example, the link 30 is a wired Ethernet type link, for example an Ethernet type link with a speed of 100 Mbit / s or higher.

[0045] The network N also comprises at least a first subnetwork, identified by the reference SN1 and a second subnetwork denoted SN2. These subnetworks each comprise a network device 34, which is connected to the backbone link 30 and which forms a head of this subnetwork SN1 or SN2. This may be a router, when the main network B and the subnetwork SN1 or SN2 are of the same nature, or a switch. The routers or switches are two intermediate network devices of the communication network N ensuring the routing of data packets and the distribution of the electrical power supply. In the example of the figure 2 , two switches 34 are connected to the backbone link 30, thus forming two separate subnetworks SN1 and SN 2. Only the subnetwork SN1 is described in the following.

[0046] The subnetwork SN1 contains at least one home automation device of the home automation system, such as one or more electromechanical actuators 2, connected to the corresponding network device 34 via a physical link 40, preferably wired, such as a four-pair Ethernet cable. Via the communication network N, each home automation device of the network can thus be controlled by a remote mobile terminal 42, connected to the communication network N for example by an Internet link 44, and whose control commands pass through the backbone physical link 30 and through the routers and / or switches 34 to the home automation device. The home automation device is also powered by the external energy supplied by the Ethernet cable.

[0047] Control boxes 36, such as switches, or remote controls, or sensors or mobile communication terminals, or computers such as a home automation system, are also part of the communication network N. They make it possible to control the electrical equipment, for example by transmitting position instructions and / or movement orders to the actuators 2. The control boxes 36 can also be supplied with electrical energy by the wired network of the physical link 40.

[0048] As shown in the figure 2 , the control board 6 of the electromechanical actuator 2 comprises an electrical power supply circuit 62 and an electronic control unit 64, described in more detail below.

[0049] Optionally, the motor 8 may comprise one or more position sensors 70, configured to measure the angular position of the rotor 82. For example, the sensor(s) 70 are Hall effect magnetic sensors, cooperating with a coding wheel integral in rotation with the rotor 82 of the motor 8 or cooperating directly with the permanent magnets of the rotor 82, these examples not being limiting.

[0050] The power supply circuit 62 is powered by the communication network N, including the sub-network SN1, through the electrical connector 18 and the complementary connector 19. The current supply to the circuit 62 is carried out under a direct electrical voltage of the order of 48V.

[0051] The power supply circuit 62 comprises a data and power divider circuit 90 to which the power supply and the data are supplied. The divider circuit 90 is adapted to divide the data and the power supply transmitted by the different wires of the Ethernet cable of the physical link 40. The data and power divider circuit 90 mainly comprises a magnetic circuit 91 and a rectifier 92 for rectifying the divided power supply. The rectifier 92 notably comprises diodes or a diode bridge or diodes ideal for limiting power losses in the rectifier 92. A voltage measurement unit 93 is adapted to measure the voltage at the rear of the data and power divider circuit 90. The voltage measurement unit 93 notably comprises a so-called signature resistor.The electromechanical actuator 2 connected to the network N is defined as compatible with the network if the signature associated with the signature resistor, which is of the order of 25 kΩ for a PoE network of standard 802.3af, is in accordance with expectations. The signature is obtained by applying a low voltage, for example between 2.7 and 10 V, as a common mode voltage to the input of the actuator 2. The voltage measurement unit 93 makes it possible to validate the presence of the signature resistor.

[0052] The power supply circuit 62 also comprises a classification negotiation circuit 94. This circuit 94 notably comprises a classification resistor. By applying a first classification voltage, the quantity of current which is used by the power supply circuit 62, determined by the value of the classification resistor, makes it possible to determine how much electrical energy the actuator 2 needs and to provide this indication to the network N. Alternatively, this classification is semi-automatic or automatic when the actuator is connected to the network N.

[0053] The actuator also includes a controller circuit 95 whose function is to identify the actuator 2 in the subnetwork SN1 and to negotiate the power supply class with the network N.

[0054] The controller 95 also receives the commands from the network N and transmitted via the connectors 18 and 19, through the divider circuit 90. The controller circuit 95 is also adapted to interface with the control unit 64 for controlling power switches 63, such as transistors. The controller circuit 95 also comprises a voltage converter, not shown, which intervenes to lower the input voltage to a voltage lower than 10V, for example 6V, for powering the electronic components of the controller circuit 95. The voltage converter does not act on the power voltage supplied to the motor 8, since the motor 8 is adapted to operate directly under the voltage supplied by the network N.

[0055] The control unit 64 is notably configured to control the motor 8 so as to set the screen 28 in motion to move it to a desired position.

[0056] For example, the control unit 64 is configured to drive the motor 8 using a pulse width modulation (or PWM) technique.

[0057] In certain examples, the control unit is further configured to control the motor 8 taking into account the angular position of the rotor 82 measured by the sensor(s) 70.

[0058] The control unit 64 here comprises an electronic control circuit 66 comprising an input interface 67, for example for collecting the measurement signals coming from the sensor(s) 70, a processor 68 and a memory 72.

[0059] For example, the 68 processor is a programmable microcontroller or microprocessor.

[0060] The memory 72 comprises executable instructions and / or software code for implementing a method for controlling the actuator 2 when these instructions are executed by the logic calculation unit.

[0061] The control unit 64 may comprise a signal output interface 74, for example for emitting control signals to control the power switches of the control circuit 62 according to orders emitted by the processor 68.

[0062] The control unit 64 may comprise an input, not shown, for receiving orders, for receiving position instructions and / or movement orders, for example opening or closing the screen 28, from a switch, or a remote control, or a mobile communication device, or a computer such as a home automation system, for example associated with the connector 18. The orders may also be received via a radio receiver of the control unit, not shown. In this case, the Ethernet link of the physical link 40 may only be used for powering the actuator 2 and not systematically for data transfer.

[0063] In order to limit the instantaneous power required that the motor 8 must provide to unroll or roll up the blind over its entire travel between its extreme positions, the actuator 2 comprises a compensation spring 24 wound around the casing 4. The compensation spring 24 is partially shown in figure 1 . The compensation spring 24 is stretched when the blind unwinds, i.e. when the screen 28 descends, and tends to resume an unstressed configuration when the blind rolls up, i.e. when the screen 28 rises. Thus, the compensation spring 24 makes it possible to reduce a maximum power Pmax supplied by the motor 8 during a raising cycle of the screen 28.

[0064] To optimize the action of the compensation spring 24, it must be pre-stressed to minimize the maximum power Pmax supplied by the motor 8 during a raising / lowering cycle of the screen 28. The pre-stress of the compensation spring 24 is expressed in turns of winding of the compression spring 24 around the casing 4. This pre-stress is adapted to a stiffness k end of the compensation spring 24.

[0065] For a range of blinds of different widths and heights, the stiffnesses and prestresses of the compensation spring 24 of each installation I may be different. In order to size a single spring 24 suitable for the entire range of blinds, i.e. for the different possible installations, the method described in the figure 2 is implemented. Thus, there is no need to choose a stiffness per installation I, which limits the manufacturing costs of the installations I and facilitates their assembly.

[0066] In a first step 100 of this method, a range of m stiffnesses of compensation springs 24 is defined, m being a natural whole number greater than or equal to 2. These stiffnesses are referenced, on the figure 4 , k 1 to km In this first step 100, the product range is also defined. It includes n products, n also being a natural whole number greater than or equal to 2, that is to say n blinds of known heights and widths, referenced PR 1 to PR n .

[0067] In an initialization step 102, a stiffness index i is initialized to 1.

[0068] Then, in a step 104, the stiffness index i is compared to the number m of stiffnesses in the stiffness range. If the stiffness index i is less than or equal to the number m of stiffnesses of the compensation spring 24, then a step 106 is implemented.

[0069] In step 106, a product index j is initialized to 1 and a stiffness ki, associated with a prestress, is selected, then, in a step 108, the product index j is compared to the number n of products considered. If the product index j is less than or equal to the number n of products considered, then, in a step 110, a maximum electrical power P j max to be supplied by the motor 8 over a cycle of raising and lowering the blind for the selected prestress of the spring ki is defined to determine the behavior of the blind. The electrical power P j max depends on the maximum torque to be supplied in the unrolled position of the blind and the electrical efficiency of the motor 8. This power P j max is stored in a memory, while being associated with the stiffness ki. Then, in a step 112, the product index j is incremented by 1 and step 108 is implemented again.

[0070] If, in step 108, the product index j is strictly greater than the number n of products, then a step 114 is implemented. In this step 114, a maximum electrical power P i max is selected, from all the maximum electrical powers P j max previously calculated in the different steps 110 and stored in memory. To do this, the highest power P j max is selected and its value is stored in memory as the maximum electrical power value P i max, while being associated with its stiffness, noted ki max. Then, in a step 116, the stiffness counter i is incremented by one and step 104 is implemented again.

[0071] If, in step 104, the stiffness counter i is strictly greater than the number m of spring stiffnesses, a final step 118 is implemented. In this step 118, the final stiffness k fin is selected by choosing, from the stiffnesses ki max determined in steps 114, the stiffness associated with the lowest electrical power P i max.

[0072] The stiffness k fin is considered to represent a satisfactory compromise for the spring stiffness constant 24 of the different actuators 2 and corresponds to the compensation spring 24 chosen for the entire product range PR j , with j between 1 and n. This stiffness k fin makes it possible to minimize the power to be supplied by the motor 6 for all models in the product range PR j .

[0073] Subsequently, the electrical power to be supplied by the blind can be minimized by adjusting the preload of the spring, the stiffness of which will have been optimally defined for a range of blinds.

[0074] Thus, the motor 2 consumes relatively little electrical energy when it operates the blind, i.e. when it unrolls or rolls up the screen 28 on the winding shaft 26, which makes it compatible with a power supply from the Ethernet network R of the installation I.

[0075] The invention is described above in the context of a solar protection installation. It can also be implemented in the context of a closing installation, where the screen 28 provides a function of closing the opening O. In this case, the screen 28 of the blind can be a grid or an assembly of slats hinged together.

[0076] The invention is described above in the case where the winding of the stator 84 of the motor 8 is designed to operate under a voltage of 48V. Alternatively, this winding can be designed to operate under a voltage of between 36V and 57V, preferably a voltage of between 46V and 57V.

[0077] Alternatively, the controller circuit 95 and the control unit 64 may be combined to form a single unit.

[0078] According to another variant, the circuit 95 and the control unit 64 may comprise common parts.

[0079] The embodiment and variants mentioned above can be combined with each other to generate new embodiments.

Claims

1. An electromechanical actuator (2) for driving a mobile closure or sun protection screen, the actuator comprising a motor (8), a control board (6), a gear reduction assembly (12) and a connector (18) for linking to a power supply source, characterized in that the connector comprises eight electrical contacts, the connector being in particular of the RJ45 type, for powering the actuator and transmitting data from an Ethernet network, the motor being a synchronous motor comprising a wound stator (84) and a rotor (82) with permanent magnets, the motor being adapted to operate directly under the voltage supplied by the Ethernet network, the winding (86) of the stator being designed to withstand a voltage of between 36V and 57V, preferably a voltage of between 46V and 57V, in particular a voltage of 48V.

2. The actuator (2) according to claim 1, characterized in that its maximum diameter is less than 60 mm, in particular less than 50 mm.

3. The actuator (2) according to any of claims 1 or 2, characterized in that it comprises a compensation spring (24).

4. The actuator (2) according to the preceding claim, characterized in that the compensation spring (24) is preloaded, a number of preload turns being adapted to a spring rate (kfin) of the compensation spring (24) and determined to minimise a maximum electrical power (Pmax) to be supplied by the motor (8).

5. A closure or sun protection system (I) comprising a blind equipped with a screen (28) and an actuator (2) for driving a winding shaft (26) of the screen, characterized in that the actuator is according to one of the preceding claims.

6. A method of dimensioning a compensation spring (24) for a range of blinds of different widths and heights, each blind incorporating an actuator (2) according to any of claims 3 or 4, characterized in that it comprises at least the following steps: • a) (100) selecting the range of n blinds (PRi) to be equipped with compensation springs; • b) (100) selecting a range of m rates (kj) of compensation springs; • c) (110) determining the behaviour of the n blinds for each spring rate (ki) in the range of m spring rates; • d) (118) selecting a single spring rate (kfin) from the range of m rates, depending on the behaviour of the n blinds determined in step c), which is suitable for the entire range of blinds.

7. The method according to claim 6, characterized by that step b) comprises the following successive sub-steps: • e) for a spring rate (ki), calculating (110) a maximum power (Pjmax) to be supplied by the motor over one up and down cycle of the blind and storage of this value in a memory for each blind (PRj) of the range of blinds considered; • f) for each spring rate (ki), selecting the maximum electrical power to be supplied (Pimax) which is the greatest among the maximum electrical powers (Pjmax) calculated in sub-step e) and storing this value, together with the associated spring rate (ki), in the memory.

8. The method according to claim 7, characterized in that the spring rate (kfin) selected in step d) (118) is the spring rate associated with the lowest power (Pimax), selected from the spring rates of step f).

9. The method according to one of claims 6 to 8, characterized in that the maximum electrical power delivered (Pjmax) for each blind depends on the maximum torque to be provided in the fully unwound position of the blind and the electrical efficiency of the motor (8).