EP1820258A1

EP1820258A1 - Method for feeding an operating motor of a rolling shutter and a device for a driven rolling shutter

Info

Publication number: EP1820258A1
Application number: EP05812272A
Authority: EP
Inventors: Serge Bruno
Original assignee: Somfy SA
Current assignee: Somfy SA
Priority date: 2004-12-07
Filing date: 2005-12-06
Publication date: 2007-08-22
Anticipated expiration: 2025-12-06
Also published as: US7746015B2; ES2307218T3; WO2006061691B1; CN101073199A; WO2006061691A1; US20080191658A1; EP1820258B1; CN101073199B; DE602005006615D1; FR2879047B1; FR2879047A1; JP2008523777A; ATE394827T1

Abstract

The inventive method makes it possible to feed an alternating current electric motor used for operating a rolling shutter in a building by means of a gear whose performance substantially varies when a movable element drives or is driven by the rolling shutter. The electric motor is supplied, in certain phases, at a reduced tension, wherein the motor slipping measuring a relative speed deviation with respect to a zero running torque speed remains less the motor slipping when the rotor thereof ruts at a nominal speed at least if the rolling shutter does not meet obstacles. The drive for the rolling shutter for carrying out said method is also disclosed.

Description

Method of supplying a motor for operating a shutter and a motorized roller shutter device

The invention relates to a method for supplying an AC electric motor used to maneuver a mobile closure, concealment, sun protection or screen element in a building. It also relates to an actuator and an installation implementing such a method.

Some actuators intended to be installed in buildings and intended for the maneuvering of closing elements, occultation, sunscreen or screen (such as for example shutters, doors, gates or blinds) include an induction motor (or asynchronous motor) single-phase permanent capacitor.

These actuators are powered by the alternating network, for example 230 V 50 Hz. They are provided with an immobilizing brake ensuring the locking of the actuator when the engine is not powered. This brake is preferably activated by the magnetic flux of the motor stator.

In frequent applications, the intensity of the load that must cause the motor varies significantly during the movement of the element. Thus, in some applications, the motor force to be applied when the abutment reaches the element is small compared to the effort required to drive the element in other parts of the race.

This is for example the case of roller shutters provided with a high stop and / or a locking device by compression of the deck, or simply attached to the winding tube by flexible metal links. When the shutter reaches a high stop, the apron is almost totally rolled up. The suspended weight of the flap is very low, as well as the torque to be supplied by the engine in this area. However, the motor is dimensioned to provide a torque at least greater than the maximum torque exerted by the rolling shutter deck on the winding tube and therefore on the actuator. If the end stop is made without precaution, the force produced by the actuator generates a high and unnecessary level of stress on the apron of the shutter and / or on the stop. It is therefore necessary to detect as soon as possible a (even) small increase in the load to be driven to stop the supply of the actuator as soon as possible to avoid unnecessary constraints. This is made difficult because of the complexity of the kinematic chain connecting the engine to the lower blade of the shutter apron.

Conversely, when the lower blade of the shutter apron touches the ground during a unwinding movement, it should be able to stop the power supply of the actuator as soon as it moves from a generator operation to a engine operation. If the shutter is equipped with a locking device operating in compression, it is quite easy to detect this change in operation by detecting a strong growth of the torque. On the other hand, if the apron is connected to the winding tube by flexible links made of metal foils, the bending force of the foils when the actuator becomes motor is too weak to be easily detected.

Patent FR 2,814,298 discloses a device for operating a mobile element of the building comprising a DC motor and in which, when the element arrives near a stop, its speed is reduced in order to avoid important constraints on the kinematic chain when arriving in abutment. This device requires a DC motor and position sensors to determine when the speed of the element needs to be reduced. EP 0 671 542 discloses a device for operating a mobile element of the building comprising an AC motor and in which, when the element arrives near a stop, a capacitor is placed in series on the motor supply phase so as to limit the supply voltage. The speed reduction detection is ensured by applying the voltage across the permanent capacitor to a means supplying a relay. This device requires the use of an electro-brake supplied independently of the capacitor. Indeed, the fact of under-energizing the motor causes the release of the immobilizing brake. However, an electro-brake is a device significantly more expensive than a brake directly activated by the stator flow of the motor. This device also requires the presence of a position sensor determining the position of the movable element in which the power supply phase under reduced voltage is engaged.

Utility model DE 200 02 225 is known, a device for supplying a permanent capacitor induction motor, in which two triacs are used to perform the functions of control switches for raising or lowering the voltage. a moving element in a building.

Patent DE 43 07 096 discloses a power supply device for an induction motor comprising two triacs, each connected in series with a winding of the motor. Controlling the states of these two triacs makes it possible to dispense with a starting capacitor or a permanent capacitor.

US Pat. No. 4,422,030 discloses a device for supplying an induction motor which makes it possible, by means of a triac, to power an engine. first at full voltage during its start-up phase, and then supply it with reduced voltage.

No. 6,777,902 discloses a device for supplying an induction motor for driving a garage door.

Depending on whether the motor drives up or down the garage door, the motor is powered to provide a different power, the capacitance capacitance value of phase shift between its windings being changed. The switches for connecting the capacitive means of different values between the windings of the motor can be made by triacs.

The application EP 1 349 028 describes a device for operating a roller shutter using an asynchronous motor. When the shutter approaches an end of stroke, the engine is driven at reduced torque. This control can be achieved by limiting the supply voltage.

EP 0 808 986 discloses a garage door operating device in which a three-phase motor is controlled to provide a variable torque depending on the load it must cause. The windings of the motor are wired in a triangle and a switch S1 is provided in a branch of the triangle. This switch is open to operate the motor at reduced torque.

DE 39 33 266 discloses a method of supplying the engine with reduced torque driving a mobile element throughout a downward phase of this movable element. This power supply is intended to substantially maintain the equality of descent and climb speeds. However, this document does not specify how to concretely achieve the torque limitation, in the case of an asynchronous motor, otherwise by action on the amplitude of the voltage. Taking action the amplitude of the wave suggests the use of a complex AC-to-AC converter, equivalent to a variable-ratio transformer, or (more likely) the use of a triac with a priming angle of greater than or greater than 90 °.

The reduction of the maximum torque of the motor leads to a significant reduction in the safety margin that results from the difference between the operating torque and the maximum torque that the engine can provide. In a driven load operation, this safety margin is equal to the difference between the nominal torque and the maximum torque that can provide the engine. In a driving load operation, the torque-speed characteristic is symmetrical with respect to the synchronism point (rotor speed = synchronism speed, zero torque). We find the same margin of safety. In either case, it is essential to maintain a sufficient safety margin.

The problem does not arise in the same way for a DC motor: in a driven load, the engine torque increases monotonously when the speed decreases (which automatically tends to stabilize the speed), and, in driving load, the Resistant torque increases monotonously as speed increases (which also tends to stabilize speed).

For an asynchronous motor, if it happens that the maximum torque that can provide the engine is exceeded, it falls into a regular decay zone of the torque as one deviates, in one direction as in the other, the speed of synchronism. This situation is therefore potentially dangerous if going uphill or downhill. An accidental overload torque is added to the load torque. An example of accidental overload is a child clinging to a roller shutter or a swing door. The process described in this application does not take into account the danger of such a situation.

The object of the invention is to provide a method of supplying an AC motor driving a mobile element overcomes the aforementioned drawbacks and having improvements over the known methods of the prior art. In particular, the feeding method according to the invention relates to an asynchronous motor, makes it possible to reduce the stresses on the mobile element and on its drive kinematic chain when it reaches the end of the race without a variation of speed of the element is noticeable by the user and allows the activation of a brake using the magnetic flux produced by the stator of the induction motor. It makes it possible to maintain a sufficient safety margin to prevent the motor from operating in an area in which its torque decreases with the absolute value of the difference between the rotor speed and the synchronism speed. The invention also relates to an actuator for implementing the method having these advantages.

The feeding method according to the invention is defined by claim 1.

Different variants of the feed method according to the invention are defined by the dependent claims 2 to 8.

The actuator according to the invention is defined by claim 9.

Different embodiments of the actuator are defined by claims 10 to 12.

The plant according to the invention is defined by claim 13. The attached drawing shows, by way of example, an embodiment of an actuator according to the invention and an embodiment of the feeding method according to the invention.

Figure 1 is a diagram of an embodiment of an actuator according to the invention.

FIG. 2 is a graph showing the characteristic curves of the variations of the torque of an engine as a function of its speed of rotation.

Figure 3 is a flow chart of an embodiment of the feeding method according to the invention.

ACT actuator shown schematically in Figure 1 allows to drive a mobile element LD closing, occultation or sunscreen equipping a building. This element can be moved in two opposite directions by rotation of an induction motor MOT in a first direction of rotation and in a second direction of rotation. The actuator is powered by the power distribution network between an AC-H phase conductor and an AC-N neutral conductor. The movable element may for example be a roller shutter comprising an apron 2 consisting of blades, rollable on a winding tube 1 and having a lower end 3 movable between an upper extreme position 5 and a lower extreme position 4.

MOT motor is asynchronous type, single phase, permanent phase shift capacitor CM. It comprises two windings W1 and W2. According to the desired direction of rotation, the capacitor CM is arranged in series with the first winding W1 or with the second winding W2. P1 and P2 denote the connection points of the capacitor CM with each of the windings W1 and W2. The other two ends of the windings are connected to a point N1, itself connected to the neutral conductor AC-N via a triac TRC.

A BRK immobilisation brake is associated with the MOT motor which blocks the rotor in the absence of current in the windings. As shown by dotted lines, the brake is magnetically coupled to each of the windings. When the motor rotor MOT rotates, it drives a gearbox GER, whose output stage drives a shaft constituting the mechanical output of the actuator. It should be noted that the connection between this output shaft and the mobile element LD is not necessarily rigid.

The connection between the phase conductor AC-H and the windings W1 and W2 of the motor are effected by means of two switches rl1 and rl2 controlled by an electronic control circuit MCU which comprises various means ensuring the control of the actuator. that is to say means for receiving and interpreting orders received, actuator supply means and means for cutting off this supply either in order or when a stop is detected. The two switches rl1 and rl2 have a common connection, connected to the phase conductor at a phase terminal PO of the actuator. The other connections of the switches are respectively connected to the connection points P1 and P2.

The control of the controlled switches results from control commands transmitted by radio frequencies.

The electronic control circuit MCU comprises a CPU processing logic unit, such as a microcontroller. This circuit includes a PSU supply circuit, typically a step-down converter, an input of which is connected to the phase terminal PO and whose other input is connected to the neutral terminal NO and constitutes the GND electric ground of the electronic control circuit. The DC output voltage VCC of the power supply circuit supplies the CPU processing logic unit and, not shown, a radio frequency receiver REC.

This radio frequency receiver REC comprises an RF input connected to an antenna ANT, and two logic outputs UP and DN respectively connected to two logic inputs 11 and 12 of the CPU processing logic unit. By means known to those skilled in the art, the radio frequency receiver interprets the received radio signal to generate, if necessary a high logic state on the first output UP or a high logic state on the second output DN, depending on whether the received signal conveys a climb order or a descent order.

According to the state of an allocation table housed in the memory of the CPU processing logic unit, an activation of the first input 11 causes a command to close the controlled switch rl1 while an activation of the second input 12 causes a command to close the controlled switch rl2.

A second state of the allocation table housed in the memory of the logic processing unit causes the opposite effect, the activation of the first input 11 causing an order of closure of the controlled switch rl2 while the activation of the second input 12 causes a closing order of the switch rh.

The logic processing unit comprises a first output O1 supplying a first relay coil RL1 and a second output O2 supplying a second relay coil RL2. These coils act respectively on a first relay contact constituting the switch rM and on a second relay contact constituting the switch rl2.

Depending on the relay coil energized, the MOT motor turns in either direction. This arrangement allows the logic processing unit to cause the motor to stop even in the presence of a movement command given by the inverter switch. It also allows to invert if necessary the relationship between each position of the inverter switch and each motor phase, depending on the state of the allocation table. This arrangement is useful when it can not predict in advance which direction of rotation of the motor corresponds to the rise (inversely to the descent) once the product installed.

Other means than relays are usable, for example triacs or transistors.

The electronic control circuit MCU comprises a torque control unit TCU which receives a voltage UCM from two diodes D1 and D2 whose anodes are respectively connected to terminals P1 and P2 of the motor. This torque control module is also connected to the electrical ground constituted by the common terminal GND. The voltage UCM is therefore referenced with respect to this common terminal GND, and it is found that, as soon as one of the controlled switches rl1 or rl2 is closed, the voltage UCM corresponds to the amplitude of the alternating voltage of the terminals. capacitor CM.

The torque control unit TCU, which is optionally supplied with voltage VCC by the power supply circuit PSU, outputs an OVL torque overload signal connected to an input 13 of the CPU processing logic unit. In the figure, the third input 13 is of the logic type and the torque control device TCU makes the state logic high its OVL overload output if the torque exceeds a predetermined value and / or if the measured torque variation exceeds a predetermined value in a given time interval.

More precisely, the torque control device TCU measures, as previously seen, a signal UCM which corresponds to the voltage across the terminals of the permanent capacitor CM. When the rotor slows, because of a larger resisting torque, this voltage decreases. It is therefore at least the decrease of this voltage in a given time interval that causes the OVL overload output to go high.

One embodiment of such a torque control device is described in patent FR 2 806 850, with reference to FIG. 1, from line 31 of page 4 to line 14 of page 6.

Alternatively, the torque control device TCU can deliver an analog voltage to the OVL overload output and the third input 13 of the CPU logic processing unit is of analog type. The processing of the study of the variations of this analog quantity is then carried out in the CPU processing logic unit.

In addition to this function, the torque control device TCU can furthermore pass a sub-charge output TL in the high state if the amplitude of the voltage at the terminals of the capacitor passes above a given threshold. which translates that the torque has fallen below a given threshold value. The underload output TL is connected to a fourth input 14 of the logic processing unit. Finally, the logic processing unit includes a third output 03 connected to the control input GCI of a triac control circuit SCU, whose control output GCO is connected to the trigger of the triac TRC.

The control circuit is also connected to the GND electrical ground and to the neutral conductor, which enables it to be informed of the times at which the network voltage is canceled and to use this information to generate a control signal for the transmission. state of the triac. The circuit contains, if necessary, electrical insulation IB between input and output, this insulation being intrinsically achieved if an opto-triac is used.

When the pilot input is low, the control circuit supplies on the control output GCO control pulses making the triac conductor immediately after the mains voltage is canceled. Thus, the motor is powered at nominal voltage with the entire sine wave of the mains voltage.

When the pilot input is in the high state, the control circuit delivers the control pulses of the state of the triac with a delay with respect to the times when the mains voltage is canceled. Preferably, this delay is less than a quarter period (ie 90 ° angularly expressed) of the mains voltage. This delay makes it possible to reduce the effective power supply voltage of the motor, and consequently the maximum torque generated by the latter, while maintaining a sufficient magnetic attraction for the immobilizing brake BRK and while keeping at the terminals of the permanent capacitor a substantially sinusoidal voltage, usable for the measurement of MOT motor torque and / or speed variations.

The rms value of the reduced voltage is preferably less than 75% of the rms value of the rated voltage. Rather than apply a same delay on the positive half-waves and the negative alternations of the mains voltage, it is possible to reduce the voltage only on the alternations of the same sign, so as to keep a full wave on the other half-waves, which disturbs the circuit less torque measuring device and / or the locking brake. For example, the delay is applied only to negative half-waves. One can also apply a delay less than a quarter of a period on the positive half-waves and a delay greater than a quarter of a period on the negative half-waves.

Alternatively, the third output 03 can directly output the triac trigger control signals if the CPU processing logic receives on another input a synchronization signal with the mains voltage. This choice is the most economical. It also makes it possible to use the triac to cause the motor to stop, rather than to open the controlled switches rh or rl2. Thus, the contacts of these switches can have a low breaking capacity.

FIG. 2 represents the torque-speed characteristic curves of an asynchronous motor powered under two voltages U1 and U2 of different effective values and the operating points of this motor according to the loads that it must cause.

The curve TM-U 1 represents, as a function of the speed of rotation of the motor, the value of the torque generated by the motor supplied at the nominal voltage U1.

The curve TM-U2 represents, as a function of the speed of rotation of the motor, the value of the torque generated by the motor supplied under the reduced voltage U2. The horizontal axis of the speeds corresponds to a null torque.

The line TL1 represents the intensity of the maximum load to which the motor is subjected during a driving cycle of the movable element between the two high and low stops (under normal operating conditions).

The line TL2 represents a predetermined intensity of the load to which the motor is subjected at certain points of the travel of the movable element.

The line TL3 represents the intensity of the minimum load to which the motor is subjected during a driving cycle of the movable element between the two high and low stops (under normal operating conditions).

For an induction motor, the motor torque TM is zero when the rotor rotates at the same speed as the rotating field generated by the alternating currents flowing in the motor windings. As is customary, this synchronism speed NS is referred to as this speed value and by sliding the relative difference between the rotor speed NR and the synchronism speed NS.

The maximum torque that can be supplied by the motor is proportional to the square of the rms value of the supply voltage. In Figure 2, there is a maximum engine torque MAX2 under reduced voltage U2 two times lower than the maximum engine torque MAX1 obtained at rated voltage U1. In other words, the effective values of the supply voltages U1 and U2 have a ratio equal to V2. This ratio between the nominal voltage and the reduced voltage can be obtained by delaying the triac control pulses of 90 ° with respect to times when the mains voltage is zero.

The nominal operating point P1 corresponds to the application of the maximum load TL1 when the motor is supplied with nominal voltage U1. Under these conditions, the rotational speed of the motor rotor is NRR, which is subsequently designated as a nominal speed value. Nominal slip is the slip at this point.

In the applications covered by the invention, the nominal slip is typically 10% or even 20%, which is substantially higher than the slips usually tolerated in industrial applications where three-phase induction motors are used.

The feeding method according to the invention aims to power under reduced voltage the motor in the phases where the nominal power of the actuator is not necessary in order to avoid too much stress on the kinematic chain connecting the moving element to the motor.

According to the invention, the passage of a power supply of the motor under nominal voltage to a power supply under reduced voltage is only possible in a power supply phase of the motor if, in spite of this power supply under reduced voltage, the motor speed decreases. not in this phase (under normal operating conditions) below the rated speed NRR. The absolute value of the slip must not exceed the value of the nominal slip, which means that, when the load is driving, the rotor speed becomes greater than the synchronism speed NS but must remain below a maximum speed value. NRMAX such as NRMAX = NS + (NS-NRR).

In this way, the passage of a supply of the motor under nominal voltage to a power supply of the motor under reduced voltage causes an imperceptible variation of speed, which does not risk disturbing the user in the case where the passage takes place while the element is still far from the end stops and especially if the reduced voltage crossing point n ' is not located in a fixed and repetitive manner. The method according to the invention is particularly advantageous if the actuator does not include a position sensor of the motor shaft or if it is intended to equip an installation not comprising a position sensor of the movable element. The fact that the absolute value of the slip does not exceed the nominal slip value also makes it possible to ensure that the motor operates in an area in which its torque increases with the absolute value of the difference existing between the speed of the rotor and the synchronism speed.

The same load does not cause the same torque at the motor, depending on whether the load is driven or driving. In the case of a roller shutter, if the load is driving, the friction forces are evading the forces induced by the suspended mass of the shutter, whereas if the load is driven, the friction forces are added to the forces induced by the suspended mass of the flap, this phenomenon can be further accentuated or attenuated by the fact that the efficiency of the gear unit GER can be significantly different depending on whether the load is driven or driving. For example, it is possible to use a gearbox with three planetary gear trains whose efficiency is greater than 70% when the load is driven and less than 60% when the load is driving. This difference in efficiency can be obtained by acting on the parameters defining the teeth of the wheels making up the gearbox and in particular by acting on the approach and retirement lengths on the lines of action. Thus, the same maximum load situation results in the torque TL1 in driving load and the TL3 torque in driven load, the absolute values of the couples being substantially different. For example, an installation comprising an actuator and a shutter actuated by this actuator may be such that the absolute value of the maximum torque exerted by the shutter on the actuator motor when it drives the shutter is at least twice the value absolute maximum torque exerted by the shutter on the motor when it is driven by the shutter.

When the load is minimum (torque value TL3), it can be seen that if the motor is powered under nominal voltage U1 or if the motor is powered under reduced voltage U2, the operating points of the motor are similar and respectively represented by point P3. and by point P5. At these two operating points, the rotor speed of the motor is lower than the maximum speed NRMAX. Thus, the motor can be powered at reduced voltage throughout the descent phase of the movable element.

During a closing phase of the mobile element, the speed of the motor gradually changes from the value corresponding to the point P5 to the synchronism speed NS. Once the movable element has reached the lower stop (and eventually the blades that compose it are stacked), the load torque becomes resistant, the operating point changes on the TM-U2 curve to point P4 . Whatever the nature of the stop, the torque can not exceed the value MAX2. The fact that the speed varies more strongly with the torque when the motor is powered under reduced voltage U2 than when it is powered under nominal voltage U1 facilitates the detection by the torque control device TCU which then enjoys a greater sensitivity .

In the same way, the device can also be used in a rising phase of a roller shutter. In this case, the motor is necessarily supplied at its rated voltage U1 at the beginning of lifting. If the movable element were completely closed, the initial speed of the motor is the synchronism speed NS, then this speed decreases progressively until NRR reaches the operating point P1 when the load is maximum, and finally the speed increases again when the load decreases.

When the movable element has reached a position such that the intensity of the load will no longer evolve in this phase beyond the value TL2, the motor is powered under reduced voltage U2. This switching of the power supply from the nominal voltage to the reduced voltage can for example be made as soon as the engine torque drops below the torque threshold TL2. Such switching causes a displacement of the operating point of the motor from the point P2 to the point P4 as shown in FIG. 2.

The variation of speed during this power switching is imperceptible by the user. This allows a very low precision and / or drifts on the position of the movable element during this switching. Thus, a simple delay can be used to set the switching time of the nominal voltage to the reduced voltage. For example, depending on the thermal state of the engine (cold and hot), the travel traveled by the movable element in a given time interval is not the same, but this variation is of no consequence since the user does not perceive the moment when it is performed. Management of the switching point allowing the arrival in abutment with a greater accuracy of detection and the guarantee of a lower maximum engine torque is thus achieved at lower cost.

The condition to be met under driven load is that it generates a TL2 resistant torque lower than that corresponding to the nominal speed NRR on the reduced voltage characteristic curve TM-U2. This condition can be established by learning, or be predetermined in an equivalent manner for example by setting a time relative to the total running time between the low and high stops.

FIG. 3 describes an embodiment of the feeding method according to the invention.

In a first step 10, a user exerts an action on a motion control command transmitter to control a movement of the movable member.

In a test step 20, it is determined whether the action exerted by the user is intended to control a moving movement of the movable element or a movement of descent of the movable element.

If the action exerted is intended to control a movement of descent of the movable element, it controls, in a step 30, a power supply of the engine under reduced voltage to rotate in a first direction causing a descent movement of the mobile element.

In a test step 40, it is determined whether a stop is reached by the movable element or if a stop command is given. If this is not the case, the method loops on step 30. The detection of a stop is for example performed by analyzing the torque and / or torque variations.

If this is the case, the motor supply is cut in a step 50 and the process loops on step 10. If the action exerted is intended to control an upward movement of the movable element, a power supply of the motor under nominal voltage is commanded in a step 60 to turn it in a second direction causing a rising movement of the motor. 'element.

In a test step 70, it is determined whether a threshold value of engine torque TL2 is crossed downwards.

If the result of the test is positive, in a step 80, it controls a power supply of the engine under reduced voltage to rotate in the second direction.

If the result of the test is negative, in a step 90, it controls a power supply of the motor under nominal voltage to rotate in the second direction.

In a test step 100, it is determined whether a stop is reached by the movable element or if a stop command is given. If this is not the case, the method loops to step 70.

If this is the case, the process loops on step 50.

The test procedure of step 70 may simply consist in checking a value stored in a counter CNT which is incremented when the motor rotates in one direction and decremented when the motor turns in the other direction and to be compared with a particular value, determined in a learning phase. In this case step 60 can be deleted. The particular value is a position value or preferably a time value which reflects, less precisely but sufficiently, the position of the movable element.

In the case of a shutter, this particular value can be determined in a learning phase as follows. The moving element is brought into a first end position, the value of the counter is initialized, the motor is controlled to drive the movable element towards the second end position and the value of the counter is stored in a memory. when the engine torque exceeds the TL2 threshold (downward if the first end position was the down position and upward if the first end position was the up position).

If there is a voltage representative of the engine torque, the crossing of a threshold value by the engine torque can be detected by crossing a threshold predetermined by this voltage. If the voltage directly at the terminals of the capacitor CM is used directly, the crossing of a threshold value by the motor torque is detected by the crossing of a threshold value by this voltage, this voltage increasing when the torque decreases. .

If the torque control device TCU allows it, it is itself which determines and indicates, on the underload output TL, when the torque value has fallen below a predetermined torque value or acquired by learning.

The particular value of the counter can also be determined more simply from a learning maneuver between the two end positions. The particular value is calculated automatically as a fraction of the contents of the counter corresponding to the total stroke, using a predetermined coefficient.

The particular value can finally be determined by a particular action of the installer on the control means at the time when he believes that the shutter passes through a position where it remains to be traveled a small fraction of the race. The manufacturer indicates for example on the installation instructions a percentage of stroke for which it is known that the torque falls below the threshold TL2.

In all cases, the advantage of the method is not to require significant precision on this particular value.

As a precaution, when switching from a full conduction mode to a reduced conduction mode, the logic processing unit does not take into account the signal delivered by the OVL overload output, so as not to cause a shutdown. untimely at this moment.

The invention has been described in the case of an actuator controlled remotely by radio. It is clear that the antenna can be replaced by a coupling on the phase conductor for transmission of orders by line carrier currents. The person skilled in the art can without difficulty use the invention in the case of a so-called wired control, that is to say for which the actuator has two phase terminals, the order being determined by the fact of connecting one or the other of these phase terminals to the AC-H phase conductor of the network, for example by means of a manual inverter with two contact positions and a neutral position.

Claims

Claims:

1. A method of supplying an AC electric motor (MOT) used to maneuver a movable closure, concealment, sunscreen or screen element (LD) in a building, via a gearbox (GER) having a substantially different performance depending on whether the movable element drives or is driven by the motor, the movable element (LD) comprising a lower end (3) whose displacements between a lower extreme position (4) and an extreme upper position (5) are caused by motor rotation movements (MOT), the electric motor being supplied, in certain phases, under a reduced voltage, the absolute value of the motor slip, measuring the relative speed difference relative to the speed at zero torque, remaining lower than the absolute value of the sliding of the motor when its rotor rotates at nominal speed, at least as long as the movable closure element does not meet as obstacle.

2. Feeding method according to claim 1, characterized in that the motor (MOT) is powered under reduced voltage to cause movement movements of the lower end (3) of the movable element to the lower extreme position ( 4).

3. Feeding method according to claim 1 or 2, characterized in that the motor (MOT) is powered at nominal voltage to cause movement movements of the lower end (3) of the movable element (LD) to the upper extreme position (5) as long as a particular condition is not fulfilled and in that the motor (MOT) is powered under reduced voltage to cause the movement movements of the lower end (3) of the movable element (LD) to the upper extreme position when the particular condition is realized.

4. Feeding method according to one of the preceding claims, characterized in that the special condition is a crossing downward of a predetermined threshold by the voltage of a signal representative of the engine torque.

5. Feeding method according to one of claims 1 to 3, characterized in that the special condition is the arrival of the lower end of the element in a position defined by a period of activation of the motor from a extreme positions of this end.

6. Feeding method according to one of the preceding claims, characterized in that the motor supply (MOT) is performed through a triac (TRC) whose state is controlled by a control device (SCU ) generating electrical pulses at a frequency twice that of the supply voltage, these pulses occurring substantially at the times when the supply voltage is zero, for supplying the motor at nominal voltage and occurring substantially after the moments when the supply voltage is canceled, for the supply of the motor under reduced voltage.

7. Power supply method according to claim 6, characterized in that, for the power supply of the motor under reduced voltage, the electrical control pulses generated by the control device (SCU) have a delay compared to the instants when the voltage The supply voltage is different depending on whether the value of the supply voltage is positive or negative.

8. Feeding method according to one of the preceding claims, characterized in that the effective value of the reduced voltage is less than 75% of the rms value of the nominal voltage.

Actuator (ACT) comprising an AC electric motor (MOT) used to maneuver a movable (LD) closure, concealment, sunscreen or screen element in a building, via a gearbox (GER) with a significantly different efficiency depending on whether the moving element

. drives or is driven by the motor, the motor being powered by an AC voltage source through a triac (TRC), characterized in that it comprises hardware means (TCU, CPU,

SCU) and software for implementing the method according to one of the preceding claims.

Actuator according to Claim 9, characterized in that the AC electric motor (MOT) is single-phase, of induction type with two windings (W1, W2) and permanent capacitor (CM).

Actuator according to claim 9 or 10, characterized in that the gear unit (GER) has a yield greater than 70% when the movable element is driven by the motor and less than 60% when the movable element drives the motor.

12. Actuator according to one of claims 9 to 11, characterized in that the gear (GER) has a yield when the movable element is driven by the motor at least 15% greater than the yield when the movable element drives the motor .

13. Installation comprising an actuator (ACT) according to one of claims 9 to 12 operating a movable member (LD), characterized in that the absolute value of the maximum torque exerted by the movable member on the motor when it causes the movable element is at least twice greater than the absolute value of the maximum torque exerted by the mobile element on the motor when the latter is driven by the movable element.