EP2899343B1 - Anti-remanence device for electromagnetic lock - Google Patents

Description

The present invention relates to an electromagnetic lock device for controlling the opening / closing of an opening adapted to a frame of a frame, in particular a door.

This type of device conventionally comprises an electromagnetic suction cup comprising an electromagnet, generally in the shape of a parallelepiped, in particular rectangle, or prismatic, received in a section in two parts, each part consisting of a U-shaped section, the two sections U-shaped interlocking one within the other receiving the electromagnet within them and secondly a counterplate of a material capable of being attracted by a magnet, in particular a ferromagnetic material, for example a metallic material.

In general, the counterplate is received in a strip section mounted along the free edge of the door, typically a door, while the electromagnetic lock is received in the frame, typically the door frame. However, the reverse arrangement is also possible.

These devices forming an electromagnetic lock have the disadvantage in particular of having a remanence effect, namely that when the electromagnetic lock is deactivated, for example by pressing the opening button, the magnetic action tending to keep the door closed by magnetic attraction of the plywood on the suction cup, the user does not succeed in opening the door without having to apply a large enough force corresponding to the force required to overcome the magnetic force related to the remanent magnetic field, that is to say the magnetic field that is maintained despite the cancellation of the cause that created it, namely the activation current.

To solve this problem, the devices of the prior art have provided to insert an anti-remanent electric circuit to send in the coil of the electromagnet an electric current in the opposite direction of the electric current magnetization.

These devices of the prior art are complex in structure and expensive to manufacture. In particular, they comprise complex electronic components, such as relays, in particular bistable or of the DPDT type, transistors, or the like. These devices, moreover, are unreliable and often fail, particularly in the case of use for a door system intended to have a high cycle of use, for example in the case of access door to public places. In addition, these anti-remanent electrical circuits of the prior art only work in one direction of the polarity of the current source, complicating their implementation in the door system.

Mechanical solutions have also been proposed. There is provided an anti-remanent device which consists of a lug received in a blind hole formed on the surface of the plywood for example and which projects from the hole by being movably mounted so as to be pushed by a spring disposed at the bottom. of the blind hole and which tends to push the lug out of the hole. When the plywood and the plunger come into mutual contact under the effect of the electromagnetic closing force of the lock, the spur, despite the spring, is pushed completely inside the hole. When the magnetic field is deactivated, there remains a remanent electromagnetic force which is less than the magnetic force in the activated state, and in particular which is lower than the spring biasing force on the pin, the stiffness constant of the spring having been previously selected in this goal. It follows that the lug emerges from the hole and spreads the suction cup, which allows the opening of the door by the user, the remanent electromagnetic force having been overcome by the action of the lug pushed by the spring.

These devices of the prior art are complicated to manufacture. In addition, due to the wear especially under the effect of corrosion, they have a limited life. Moreover, the pushing action of the pin in the hole by the electromagnetic force in the activated state decreases by the magnetic force available to press the two elements of the electromagnetic lock against each other.

Of EP 0 045 197 , an anti-remnant system is known according to the preamble of claim 1.

The present invention aims to overcome the disadvantages of the prior art by proposing a device of the above kind which is simpler and more reliable structure.

According to the invention, an electromagnetic lock device is as defined in claim 1.

According to the invention, the energy of the cut-off voltage which is necessarily created when the power supply is cut off in the form of a negative voltage pulse is thus used by damping it on its return to the zero-volt level. to return a current in the coil to fight against the lingering effect. This gives a simple and reliable structure system. In particular, it is no longer necessary, as was the case in the devices of the prior art, to use complicated electronic components, such as DPDT relays (Double Poles, Double Lanes) to perform a reverse inversion. polarity across the coil to send a current in the opposite direction. This avoids the formation of particular sparks (during the sudden passage of relays from an open position to the other closed position) likely to deteriorate the device, especially in the case of a high duty cycle. In addition, the use of the pulse current sent into the coil during the breaking ensures a curve giving the intensity of the current in the coil as a function of time which remains continuous, ie without sudden jump or discontinuity that may cause damage to the device.
Preferably, means are provided for limiting the maximum absolute value of the cut-off voltage pulse, in particular means in the form of a varistor mounted across the at least one coil.

According to the invention, however, the means for limiting the maximum absolute value limit the absolute value of the maximum voltage to a value greater than the supply voltage.
Preferably, the electrical circuit is arranged so that the voltage, after having passed once the zero back of the peak of the cut-off pulse, possibly damped by the limiting means, in particular the varistor, oscillates around zero while being damped. , in particular by becoming substantially zero after one or two pulse periods.
Preferably, the arrangement is such that the device operates even if the polarity of the current source is reversed.
Preferably, the electrical circuit comprises at least one unpolarized capacitor and a series resistor connected in parallel across the at least one coil of the electromagnet.

According to a particularly advantageous embodiment, in particular by its simplicity of design and its reliability, the electric circuit comprises a circuit consisting of two series-connected polarized capacitors mounted in parallel to the terminals of the at least one coil of the electro magnet.

The present invention also relates to a door device comprising an opening and a frame and an electromagnetic lock device according to the invention, one of the two elements of the electromagnetic lock device, namely the electromagnetic lock and the counter plate, being attached to the opening, while the other of the two elements is fixed to the frame.

The present invention also relates to a module forming anti-remanence device for an electromagnetic lock intended to be integrated in an electromagnetic lock and in particular in the electrical or electronic control circuit of the electromagnetic lock, the module comprising an electric circuit arranged so that the power supply source is mounted directly across the at least one coil so that when the interrupting means cuts off the power supply, a breaking voltage in the form of a pulse is applied to the coil and the electric circuit comprises means for delaying the zero crossing in return of the pulse, in particular of a duration at least equal to 40 thousandths of a second (ms), preferably at least 100 ms, even more preferably greater than 150 ms, for example between 100 ms and 300 ms.

According to a particularly advantageous embodiment, in particular by its simplicity of design and its reliability, the electrical circuit of the module comprises two capacitors polarized in series, in particular mounted head to tail.

According to yet another embodiment, the electrical circuit of the module comprises an unpolarized capacitor and a series resistor.

la figure 1

est une vue en perspective d'un dispositif de porte comportant une porte formant l'ouvrant et un dormant encadrant l'ouvrant et une serrure électromagnétique pour assurer l'ouverture et/ou la fermeture de la porte ;

la figure 2

représente un schéma simplifié du circuit électrique de commande du courant passant dans la bobine de l'électroaimant de la ventouse électromagnétique qui commande l'ouverture/fermeture de la serrure de la figure 1 ;

la figure 3

représente la courbe donnant la tension aux bornes de la bobine en fonction du temps, à partir d'un point dans le temps un peu avant l'interruption de l'alimentation; et

la figure 4

est un schéma d'un autre mode de réalisation du circuit électrique de commande de la serrure de la figure 1.

By way of example only, embodiments of the invention are described with reference to the drawings in which:

Figure 1

is a perspective view of a door device comprising a door forming the opening and a frame framing the opening and an electromagnetic lock to ensure the opening and / or closing of the door;

Figure 2

represents a simplified diagram of the electrical circuit for controlling the current flowing in the coil of the solenoid electromagnet that controls the opening / closing of the lock of the figure 1 ;

Figure 3

represents the curve giving the voltage across the coil as a function of time, from a point in time a little before the interruption of the supply; and

Figure 4

is a diagram of another embodiment of the electric control circuit of the lock of the figure 1 .

To the figure 1 , there is shown an access opening / closing system, comprising an opening, for example a door P, which, depending on its position, closes a door opening delimited by a frame, for example a frame D, or on the contrary, lets access.

The opening / closing of the door is controlled by an electromagnetic lock, comprising two elements, an electromagnetic suction cup and a counterplate 1. The electromagnetic suction cup comprises two U-shaped profiles, nested one inside the other so as to define a closed enclosure inside which is housed an electromagnet 4 intended to create a magnetic field to attract the counterplate 1 against the electromagnetic lock with a force greater than at least the maximum force that a human is able to provide to open the door .

In the closed enclosure defined by the two U-shaped profiles, is also received an electrical control circuit of the electromagnet, for example mounted on an electronic card.

The electrical or electronic circuit comprises a power supply, for example in the form of a battery 2 which, depending on the applications, may have a value Vo which can be between 8 and 64 volts, for example 12 V, 24 V or 48 V , intended to pass in a coil L of inductance of the electromagnet a magnetization current. This range of voltage and these voltage values are, however, given by way of example, and other larger values of the voltage may be provided without departing from the scope of the invention.

In the present application, the electromagnet is described as having a single inductance coil. However, this is only for the purpose of simplifying the description, and it goes without saying that one can either provide several coils forming an equivalent coil which can then be considered as being said at least one coil of the electromagnet, or provide several coils and consider only one under the said at least one coil.

A switch 10 allows the circuit break. The switch 10 is connected to a control button of the opening of the door.

In addition, a circuit module 22 consisting of two polarized capacitors 20 and 21 connected in series head to tail, is connected in parallel across the inductance L of the electromagnet. This module 22 circuit has the function, when the current flowing in the coil is cut by the opening of the switch 10, in a first step to take the energy of the cutoff voltage pulse created by the opening of the switch by charging one of the two capacitors, and discharging the other capacitor to send a current in the coil in the opposite direction of the current flowing in the coil before opening the switch, to cancel or overcome the field magnetic remanent.

When the switch 10 is closed, the door is normally closed and an electric current passes through the coil, which creates a magnetic field. This magnetic field attracts the counterplate in a ferromagnetic material, for example metal, against the sucker and prevents the opening of the door.

When a user comes to open the door, he can for example press a button (possibly after typing an access code) or introduce a smart card or the like to activate a circuit that is connected to the switch. so that the actuation of the button causes the opening of the switch. The magnetization current supply by the battery 2 is then cut off.
Switching off the power supply by opening the switch creates a cut-off voltage pulse having a value equal to -Vm (see FIG. figure 3 ).
Preferably, a varistor V has been mounted across the coil and the module 22 to limit the absolute value Vm of the maximum voltage of the cut-off pulse. However, Vm is limited to a value greater than V0 (as shown in FIG. figure 3 ).
Almost simultaneously with the opening of the switch and the interruption of the power supply, the capacitors 20 and 21 then perform a charge-discharge cycle which creates a negative transient current in the coil. This transient current, which typically only lasts a few milliseconds, has the effect of canceling or greatly reducing the remanent magnetic field. As a result, the user can open the door without having to overcome the electromagnetic force resulting from the remanent magnetic field. During this charge-discharge cycle, the two capacitors reverse their respective polarities and are available immediately for a new cycle.

For example, for a supply of 12V respectively 24V, respectively 48V, the current flowing in the coil is 500mA, 250mA and 125mA. The internal resistance of the power supply may for example be respectively 25, 100, 400 Ohms, without the invention being limited in any way to this value.

The two capacitors, which may be in particular capacitors of the Jamicon brand, have for example a capacity of 1000 microfarads for a nominal voltage of 25V, without the invention being limited in any way to this value.

It can be provided to add a resistor R in the circuit 22. however, it is an optional feature. In addition, it is preferable not to place it between the two capacitors 20 and 21.

The characteristic value of the inductor is for example equal to 2800H / 24Volts, without the invention being limited in any way whatsoever to this value.

To the figure 3 , it is represented the curve giving the voltage across the coil L from a few moments before the opening of the switch 10.

This curve is continuous, that is to say that it does not include discontinuity such as sudden jumps, from the switch off to to.

At instant to, the user presses the door opening button, switching on the switch in the open state. The voltage across the coil then drops very quickly creating a pulse of voltage (of the order of 1ms) up to a value Vm. This is the classic phenomenon of cut-off voltage.

Varistor V limits the value Vm.

The action of modules 22 or 22 "to figures 2 and4, respectively, has the effect of slowing down the rise of the curve (with respect to a conventional cut-off voltage pulse) so that the voltage becomes zero again for the first time only after a time interval ΔTo which is at least 40 ms, preferably at least 100 ms, still more preferably at least 150 ms, in particular between 120 ms and 300 ms. A current has thus been created in the coil sufficient to cancel the residual magnetism or remanence.

In the preferable case where Vm is greater than Vo (for example between 1.5 times and 3 times Vo) the electrical circuit (especially in the case where it comprises one of the modules 22 or 22 ") is such that the voltage returns to the value -Vo after a time interval Δto greater than 40ms, especially greater than 70ms.

This provides a cancellation of the remanence effect in a time of the order of a tenth to a few tenths of a second, imperceptible to the user, which does not have the impression of having a force to overcome to open the door. Then, the damping of the sinusoidal shape takes place in a few oscillations, in a time of a few thousandths of a second.

In addition, after zero crossing at + ΔTo, the voltage is sinusoidally amortized around zero. In particular, the half oscillation period (Δt1-ΔTo at the figure 3 ) is of the order of 100ms. At the end of a period of oscillation, the voltage is almost zero.

To the figure 4 , there is shown a diagram of another electrical circuit, including electronic control of the current flowing in the coil of the electromagnet.

To form the electric current, a current source is used in the form of a battery 2, with a nominal voltage of for example 12V, 24V or 48V. The current flowing in the coil is 500mA, 250mA and 125mA. The internal resistance of the power supply may for example be respectively 25, 100, 400 Ohms, without the invention being limited in any way to this value. The characteristic value of the inductor is for example equal to 2800H / 24Volts, without the invention being limited in any way whatsoever to this value.

In addition, a circuit module 22 "in the form of a non-polarized capacitor 34 and a resistor R 'connected in series is mounted across the inductor in parallel with the latter.

This module 22 circuit has the function, when the current flowing in the coil is cut by the opening of the switch 10, in a first step to take the energy of the cutoff voltage pulse created by the opening of the switch by charging one of the two capacitors, and discharging the other capacitor to send a current in the coil in the opposite direction of the current flowing in the coil before opening the switch, to cancel or overcome the field magnetic remanent.

The capacitor 34 and the resistor R 'can, for example and without the invention being limited to these values, have the characteristic values respectively of 25V / 1000μF and 100 Ohms.

The curve giving the intensity passing through the coil L from a few moments before the opening of the switch is of identical shape to that shown in FIG. figure 3 for the circuit of the figure 2 and has the same characteristics.

In particular, from the point to, moment of opening of the switch, the intensity decreases along a slope such that the current becomes zero after a time interval of a few thousandths of a second. Once the intensity has been canceled, all the energy of the coil has been recovered by the module 22 "and the capacitor 34 discharges through the resistor R 'until the current reaches the lowest point of the curve. At this moment, about a few thousandths of a second, the remanence is then erased and the door opens without difficulty.Then the same cycle as above starts again, but strongly damped, during a few oscillations, before final extinction of the current.

In the figures, the embodiment described provides for fixing the plywood to the opening and the suction cup to the frame. However, according to another embodiment forming part of the scope of protection of the present invention, the reverse can be provided.

In addition, whether it's mounting the figure 2 or from figure 4 , the system works the same way when we reverse the polarities of the source 2 of current, only the directions of currents respectively of magnetization and anti-remanence being reversed.

Claims (12)

1. Device forming an electromagnetic lock comprising an electromagnetic suction pad (3) comprising an electromagnet (4), a counter plate (1) and an electric circuit comprising a source (2) of current designed to supply at least one coil (L) of the electromagnet of the electromagnetic suction pad with an electric magnetisation current to create an electromagnetic field and an associated electromagnetic force pinning the counter plate and the electromagnetic suction pad against one another to close the lock; switching means (10) designed to disconnect the current supply; and anti-remanent means for dealing with the remanent electromagnetic force which remains when the switching means (10) have disconnected the supply (2) of current to the coil of the electromagnet, wherein the electric circuit is set up such that the source (2) of the current supply is mounted directly at the terminals of the at least one coil (L) such that when the switching means (10) disconnects the supply of current, a disconnection voltage (-Vm) in the form of a pulse, in particular a negative pulse, appears at the terminals of the coil characterised in that the absolute value (Vm) of the disconnection voltage is greater than the absolute value (Vo) of the supply voltage and the electric circuit comprises means (22; 22") for delaying the switchover to zero on return of the pulse, in particular for a duration of at least 40 milliseconds (ms), preferably at least 100 ms, even more preferably more than 150 ms, for example between 100 ms and 300 ms.
2. Device according to claim 1, characterised in that means are provided for limiting the maximum absolute value of the voltage disconnection pulse, in particular means in the form of a varistor mounted at the terminals of the at least one coil, the means for limiting the maximum absolute value limit the absolute value of the maximum voltage to a value greater than the supply voltage.
3. Device according to one of claims 1 or 2, characterised in that the electric circuit is setup such that the voltage having passed zero once on return from the peak of the disconnection pulse and possibly damped by the limiting means, in particular the varistor, oscillates around zero while being dampened, in particular becoming substantially zero after one or two pulse periods.
4. Device according to one of claims 1 to 3, characterised in that the electric circuit comprises at least one capacitor (20, 21; 34).
5. Device according to claim 4, characterised in that the electric circuit comprises two polarised capacitors (20, 21) in series mounted head to tail.
6. Device according to claim 5, characterised in that the two capacitors (20, 21) in series are mounted in parallel with the power supply (2).
7. Device according to claim 5 or 6, characterised in that the two capacitors (20, 21) in series are mounted in parallel with the inductance coil (L) of the electromagnet (4) of the suction pad.
8. Device according to claim 4, characterised in that the electric circuit comprises a non-polarised capacitor (34) mounted in series with a resistor (R'), mounted in parallel with the at least one coil (L).
9. Module forming an anti-remanent device for an electromagnetic lock designed to be integrated into an electromagnetic lock and in particular into the electric or electronic control circuit of the device according to one of the preceding claims, the module comprising means for delaying the switchover to zero on return of the disconnection voltage pulse coming from the power source of the circuit, in particular for a duration of at least 40 milliseconds (ms), preferably at least 100 ms, more preferably more than 150 ms, for example between 100 ms and 300 ms.
10. Module according to claim 9, characterised in that it comprises two polarised capacitors mounted in series.
11. Module according to claim 10, characterised in that the two capacitors are mounted head to tail.
12. Device forming a door comprising an openable part (P) and a frame (D) and a device forming an electromagnetic lock according to one of claims 1 to 8, one of the two elements of the device forming an electromagnetic lock, namely the electromagnetic suction pad (3) and the counter plate (1), being fixed to the openable part, whereas the other of the two elements is fixed to the frame.

Images