EP2109871A1

EP2109871A1 - Device for switching on and off an electric circuit

Info

Publication number: EP2109871A1
Application number: EP08707924A
Authority: EP
Inventors: Hugues Filiputti; Mathias Lamien
Original assignee: Schneider Electric Industries SAS
Current assignee: Schneider Electric Industries SAS
Priority date: 2007-01-19
Filing date: 2008-01-16
Publication date: 2009-10-21
Anticipated expiration: 2028-01-16
Also published as: JP2010517212A; US8446241B2; DE602008002897D1; EP2109871B1; US20100089739A1; JP5133354B2; CN101622684A; RU2410790C1; ES2352412T3; WO2008090065A1; ATE484068T1; CN101622684B; FR2911719A1; FR2911719B1

Abstract

The invention relates to a device for switching on and off an electric circuit comprising: a charge (5) which can be ignited, the combustion of which brings about the switching on or off of the electric circuit, ignition means for the pyrotechnic charge (5), characterized in that: the ignition means are connected to the electric circuit and the ignition means comprise a microswitch (M, M') with magnetic action for controlling the ignition of the pyrotechnic charge (5).

Description

Device for interrupting / switching on an electrical circuit

The present invention relates to a device for interrupting / switching on an electric circuit. This device operates from a pyrotechnic charge.

It is known in particular from DE 44 06 730 a device for interrupting an electrical circuit. This device comprises in particular a pyrotechnic actuator comprising a pyrotechnic charge and a piston controlled in translation under the effect of the gases generated by the combustion of the pyrotechnic charge. The piston carries a finger capable of coming to press a connection bridge initially making the electrical connection between two conductors. This bridge is mounted on a spring. In operation, the gases generated by the combustion of the pyrotechnic charge cause the piston in motion to push on the bridge to disconnect the two conductors and thus interrupt the electrical circuit.

To control the initiation of the pyrotechnic charge, this device of the prior art requires the use of an external sensor. In addition, it uses mainly mechanical means that are likely to wear over time, may cause malfunctions.

The object of the invention is to propose a device for interrupting / switching on an electrical circuit which is not sensitive to wear over time and which operates using a pyrotechnic charge whose ignition is controlled. directly in the device.

This object is achieved by a device for interrupting / switching on an electric circuit, comprising: a pyrotechnic charge intended to be initiated in combustion to cause the interruption or engagement of the electrical circuit, the ignition means of the pyrotechnic charge, characterized in that: the ignition means are connected to the electrical circuit, the ignition means comprise a microswitch with magnetic actuation adapted to control the ignition of the pyrotechnic charge.

According to a particularity, the microswitch is placed on a circuit branch connected on the one hand to the electric circuit and on the other hand to the ground. According to another particularity, the ignition means comprise a heating resistive element mounted in series with the microswitch and able to initiate combustion of the pyrotechnic charge.

According to a first variant embodiment, the microswitch is controlled by a mobile permanent magnet, for example actuatable in translation.

According to a second variant embodiment, the microswitch is controlled by an excitation coil.

In a first configuration, the excitation coil is connected in parallel with the electric circuit. The device of the invention is then a device for interrupting the electrical circuit in which the electric circuit comprises two conductors and a connecting piece displaceable under the effect of the gases generated by the combustion of the pyrotechnic charge, the connection piece connecting initially both drivers.

In a second configuration, the excitation coil is connected in parallel with the microswitch. In this case it is controlled by a sensor. The device of the invention is then an engagement device in which the electrical circuit comprises two conductors and a movable connection piece under the effect of the gases generated by the combustion of the pyrotechnic charge. In this interlocking device, the connection piece is initially disconnected from the two conductors and is for example integral with a piston separating a first chamber comprising the pyrotechnic charge of a second chamber through which the two conductors pass.

According to the invention, the micro-switch employed comprises for example a membrane of ferromagnetic material capable of being controlled between two positions by aligning with the field lines of a magnetic field.

Other features and advantages will appear in the detailed description which follows with reference to an embodiment given by way of example and represented by the appended drawings in which: FIG. 1 schematically represents a device for interrupting a electrical circuit according to the invention, responding to an external mechanical action, FIG. 2 diagrammatically represents a device for interrupting an electric circuit according to the invention, responding to an overcurrent in the electrical circuit, FIG. 3 schematically represents a device for switching on an electric circuit according to the invention, FIGS. 4 to 8 show a first variant of a microswitch used in the invention,

Figures 9 to 11 show a second variant of a microswitch used in the invention.

The invention relates to a device for interrupting or interlocking a main electrical circuit. This main electrical circuit can for example be reserved for the supply of a battery, transformers, elevator brakes or all types of circuits requiring a break or a quick and reliable engagement.

The interruption devices represented in FIGS. 1 and 2 and the interlocking device represented in FIG. 3 each comprise a body 1 traversed by two spaced apart electrical conductors 6a, 6b connected to a main electrical supply circuit (FIG. 1), for example of an apparatus A powered by a generator G. In an interruption device, these two conductors 6a, 6b are initially joined by a movable connecting piece 7 initially making the electrical connection while in the interlocking device, these two Conductors 6a, 6b are initially spaced apart and are intended to be connected by a movable connecting piece 700. The body 1 of these devices is hermetically closed and has a bottom wall on which a breaking primer groove 8 is formed.

In the interruption devices, the connecting piece 7 is for example wedged between the two conductors 6a, 6b and the bottom wall of the body.

A pyrotechnic charge 5, for example of the composite type, is placed inside the body 1. The combustion initiation of this charge 5 makes it possible to generate gases inside the body 1 and to cause the interruption of the circuit electrical main or the engagement of the main electrical circuit by moving the connecting piece 7, 700. The gases are released by bursting of the body 1 along the groove 8 of incipient fracture.

According to the invention, the interruption / engagement devices also comprise a microswitch M, M 'with magnetic actuation as described herein below. below. This type of microswitch is particularly advantageous because it is housed in a perfectly hermetic housing and because it is insensitive to static electricity problems that can cause untimely firing of the pyrotechnic charge. It may in particular be manufactured by a MEMS (Micro-Electro-Mechanical System) type of technology.

Two variants of this type of microswitch M, M 'are shown in FIGS. 4 and 9. Other types of microswitches that perfectly meet the needs of the invention could be envisaged, in particular microswitches of the "type". reed ".

In both embodiments shown in Figures 4 and 9, the microswitch M, M 'comprises a movable element mounted on a substrate S made of materials such as silicon, glass, ceramics or in the form of printed circuits. The substrate S carries for example on its surface 30 at least two contacts or conductive tracks 31, 32 plane, identical and spaced apart, intended to be electrically connected by a movable electrical contact 21, 21 'in order to obtain the closure of a circuit electric. The movable element is composed of a deformable membrane 20, 20 'having at least one layer of ferromagnetic material. The ferromagnetic material is for example of the soft magnetic type and can be for example an alloy of iron and nickel ("permalloy" Ni ₈ oFe ₂ O) - Depending on the orientation of a magnetic component created in the membrane, the membrane 20 , 20 'can take a low position, said closure, in which its movable contact 21, 21' electrically connects the two tracks 31, 32 fixed conductors so as to close the electrical circuit or a raised position, said opening , in which its movable contact 21, 21 'is away from the two conductive tracks so as to open the electric circuit. In the open position, the free space must be sufficient to maintain the "no fire" standard in case of parasitic current.

In the first variant shown in FIG. 4, the membrane 20 of the microswitch M has a longitudinal axis (A) and is integral with the substrate S via two connecting arms 22a, 22b connecting said membrane 20 to two anchoring studs 23a, 23b arranged symmetrically on either side of its longitudinal axis (A) and extending perpendicularly to this axis (A). By twisting the two linking arms 22a, 22b, the membrane 20 is able to pivot between its open position and its closed position along an axis of rotation (R) parallel to the axis described by the contact points of the membrane 20 with the electrical tracks 31, 32 and perpendicular to its longitudinal axis (A). Its movable electrical contact 21 is disposed under the membrane 20, at one end thereof.

In this first variant, the magnetic actuation of the microswitch M consists of subjecting the membrane 20 to a permanent magnetic field B ₀ , preferably uniform and for example of direction perpendicular to the surface 30 of the substrate S to maintain the membrane 20 in each of its positions, and to apply a temporary magnetic field Bc control to control the passage of the membrane 20 from one position to another, by inverting the magnetic torque exerted on the membrane 20. Force the membrane 20 to 20 opening by employing a temporary magnetic field B ₀ may be necessary to resist electrostatic discharges and to give the microswitch M a strong galvanic isolation. However, it is possible to dispense with the application of the permanent magnetic field B ₀ if the membrane at rest ensures sufficient opening space. To guarantee this space with sufficient opening, the membrane 20 may be mechanically prestressed, for example by adding a layer made of a prestressed material.

To generate the permanent magnetic field B ₀ , a permanent magnet (not shown) is used, for example fixed under the substrate S. The temporary magnetic field Bc is for example generated using an excitation coil 4 associated with the microphone -M switch M. This excitation coil 4 may be planar (Figure 5), integrated in the substrate, or external, for example solenoid type. The passage of a current in the excitation coil 4 generates a temporary magnetic field direction parallel to the substrate S and parallel to the longitudinal axis (A) of the membrane 20 to control, according to the direction of the current in the coil, the tilting of the membrane 20 from one of its positions to the other of its positions. The operation of such a microswitch M is detailed below in connection with FIGS. 6 to 8. In FIGS. 2 and 3, the coil 40, 400 is represented in the form of a winding, but it should be understood that it can take any other form, in particular a planar shape integrated in the substrate of the microswitch M (FIG. 5).

The substrate S supporting the membrane 20 is placed under the effect of the permanent magnetic field B ₀ already defined above. As represented in FIG. 6, the first magnetic field B ₀ initially generates a magnetic component BP ₂ in the membrane 20 along its longitudinal axis (A). The magnetic torque resulting from the first magnetic field B ₀ and the BP component ₂ generated in the membrane 20 holds the membrane 20 in one of its positions, for example the open position in FIG. 6. With reference to FIG. 7, the passage of a control current in a defined direction through the excitation coil 4 makes it possible to generate the temporary control magnetic field Bc whose direction is parallel to the substrate S, its direction depending on the direction of the current fed into the coil 4. the temporary magnetic field Bc generates the magnetic component BP ₃ in the magnetic layer of the membrane 20. If the control current is supplied in an appropriate direction, this new magnetic component BP ₃ opposes the BP ₂ component generated in the magnetic layer of the membrane 20 by the first magnetic field B ₀ . If the BP component ₃ is of greater intensity than that generated by the first magnetic field B ₀ , the magnetic torque resulting from the first magnetic field B ₀ and this BP ₃ component is reversed and causes the membrane 20 to tilt. opening position to its closed position (Figure 7).

Once the diaphragm 20 has been tilted, the current supply of the coil 4 is no longer necessary. According to the invention, the magnetic field Bc is generated only transiently to tilt the membrane 20 from one position to another. As represented in FIG. 8, the membrane 20 is then kept in its closed position under the effect of the only first magnetic field B ₀ creating a new magnetic component BP ₄ in the membrane 20 and therefore a new magnetic torque imposing on the membrane 20 to stay in its closed position (Figure 8).

In the second variant shown in FIG. 9, the membrane 20 'of the microswitch M' has a longitudinal axis (A ') and is connected at one of its ends via connecting arms 22a', 22b ' , at one or more anchoring studs 23 'integral with the substrate S. The membrane 20' is able to pivot relative to the substrate along an axis (R ') of rotation perpendicular to its longitudinal axis (A'). The link arms 22a ', 22b' form an elastic connection between the membrane 20 'and the anchor stud 23' and are flexibly biased during the pivoting of the membrane 20 '.

In this second embodiment, the magnetic actuation of the microswitch M 'is illustrated in Figures 10 and 1 1. It consists in applying a magnetic field created by a permanent magnet 4'. According to this mode of actuation, the ferromagnetic membrane 20 'moves between its two states by aligning with the field lines L of the magnetic field generated by the permanent magnet 4'. The magnetic field created by the permanent magnet 4 'has indeed L-shaped field lines whose orientation generates a magnetic component (BP' _O , BP'-i) in a ferromagnetic layer of the membrane 20 'along its longitudinal axis (AT'). This component magnetic (BP ' _O , BP ^) generated in the membrane 20' generates a magnetic torque imposing the membrane 20 'to take one of its open positions (Figure 10) or closure (Figure 11). By moving the permanent magnet 4 ', it is therefore possible to subject the membrane 20' to two different orientations of the field lines L of the magnetic field of the permanent magnet 4 'and to tilt the membrane 20' between its two positions . To tilt the membrane 20 ', the displacement of the permanent magnet 4' can be made in a direction parallel to the surface 30 of the substrate S or perpendicular to this surface 30.

The body of the devices therefore also contain means for igniting the pyrotechnic charge 5 composed in particular of a microswitch M, M 'as described above and a heating resistive element, such as for example a resistive wire. 9, whose heating for initiating combustion pyrotechnic charge 5 is controlled by the microswitch M, M '. The microswitch M, M 'is placed in series with respect to the resistive wire 9, itself connected on the one hand to earth and on the other hand to the main electrical circuit when the microswitch M, M' is closed . The resistive wire 9 is located near the pyrotechnic charge 5, preferably in contact therewith or encased by it (variant not shown). As a variant, the combustion initiation of the pyrotechnic charge 5 can be carried out directly by the microswitch without the use of the resistive wire 9. In fact, from a certain current, the microswitch can it is designed to volatilize by producing the energy required to ignite the pyrotechnic charge 5. For this, the microswitch comprises for example a fuse 20 adapted to volatilize when the controlled current is too strong.

A first configuration of an interruption device is shown in FIG. 1. This interruption device is intended to react to an external mechanical action. This external mechanical action can be performed by various means, such as for example an increase in the pressure of a fluid (air, water or oil) or the action of an external mechanical part set in motion following a temperature variation. or in response to a shock. Any other type of sensor could be envisaged, in particular a "multiphysics" sensor producing a mechanical response as a function of the variation of various physical parameters such as pressure, temperature, speed, etc.

In this first configuration, the device comprises a movable permanent magnet 10, for example in the form of disk or torus, mounted on a mobile actuator OA on which the external mechanical action is exerted, so as to coaxial with respect to the axis (X) of the device. This actuating member OA is able to move in translation during the application of a minimum external mechanical action calibrated, for example by means of a bellows mechanism 11, of an elastic membrane with sudden rupture (no shown) or with the aid of a fixed magnet in the form of a disk or a torus (not shown) arranged concentrically with respect to the moving permanent magnet 10. Driven by the actuator OA, the magnet Mobile standing 10 can therefore translate along the axis (X) of the device between a rest position and a working position.

In this first configuration, the microswitch M 'employed is of the type of the second variant described below. This microswitch M 'is offset relative to the axis (X) of the device so as to be able to switch under the influence of the magnetic field created by the moving permanent magnet 10.

The operation of this first configuration of the interruption device is as follows:

When an external mechanical action of determined minimum intensity is exerted on the actuating member OA, the latter moves in translation along the axis (X) of the device by driving the movable permanent magnet 10. In its position rest, the mobile permanent magnet for example has no influence on the microswitch M '. The membrane 20 'of the microswitch M' is then in a rest position, parallel to the substrate as shown in FIG. 9 or raised as shown in FIG. 10 by internal mechanical prestressing. When the movable permanent magnet 10 is in its low working position, its magnetic field induces a magnetic component in the membrane 20 'creating a magnetic torque imposing the closed position on the microswitch M' (Figure 1 1).

Closing the microswitch M 'causes a sudden grounding to heat the resistive wire 9 and volatilize so as to produce the energy necessary for the initiation of the pyrotechnic charge 5.

The gases generated by the combustion of the pyrotechnic charge 5 then cause the bursting of the body 1 according to its breaking point 8 and simultaneously the ejection of the connecting piece 7, so as to interrupt the main electrical circuit between the two conductors 6a. , 6b.

In the second configuration of the interruption device shown in FIG. 2, the moving permanent magnet 10 is replaced by an excitation coil 40 arranged in the axis (X) of the device. This interruption device is therefore no longer sensitive to an external mechanical action but to an electrical signal.

The microswitch M employed in this configuration is of the type of the first variant described above. It is therefore polarized by a fixed permanent magnet (not shown) for example secured to the substrate S and creating the magnetic field B ₀ initially maintaining the microswitch M in the open position. The microswitch M is offset with respect to the axis of the coil 40 so as to be under the influence of its substantially horizontal field lines. When the coil 40 is activated, the microswitch M is therefore placed under the dominating influence of the temporary magnetic field Bc (FIG. 7) parallel to its substrate S and controlling its membrane 20 between its two positions.

In Figure 2, the excitation coil 40 is represented by a winding around a carcass but it should be understood that it can take any other form. As shown in FIG. 5, it can notably be of planar type, integrated in the substrate S supporting the microswitch M.

The excitation coil 40 is connected in parallel with the main electric circuit so as to be traversed by the current of the main electrical circuit. The field generated by the coil 40 being proportional to the current flowing through it, the microswitch M can thus switch when the current exceeds a threshold value determined by the device to be protected. When this threshold value is exceeded, the temporary magnetic field Bc created by the excitation coil 40 generates a magnetic component in the membrane 20 of the microswitch M, of sufficient intensity to impose its closed position (FIGS. 7 and 8). ), causing as in the first configuration, the ignition of the pyrotechnic charge 5 and the interruption of the main electrical circuit by ejection of the connection piece 7.

The interlocking device shown in FIG. 3 also operates by means of an excitation coil 400 which is here connected in parallel with the resistive wire 9 and the microswitch M 'employed. The microswitch M 'employed in this interlocking device is of the type of the first variant described above (FIGS. 4 to 8). Its membrane 20 is polarized by a fixed permanent magnet (not shown) and is controlled between its two positions by the temporary magnetic field Bc created by the coil 400. As previously, the coil 400 may be of planar type, integrated into the substrate S of the microswitch (Figure 5). The excitation coil 400 is for example controlled at the closing by a sensor C. This sensor C can for example take the form of a switch sensitive to one or more physical parameters, such as temperature, pressure, acceleration, etc. It is in particular possible to envisage an acceleration sensor comprising a plurality of MEMS-type microswitches conforming to FIG. invention placed on the electric circuit in series with the micro-switch M of ignition control of the load 5. A permanent magnet is for example set in motion according to the intensity of the acceleration or deceleration to operate more or less micro-switches. When an acceleration or deceleration threshold is reached, all the microswitches are closed allowing the passage of current to the excitation coil 400.

The connecting piece 700 is mounted integral with a piston P separating the internal space of the body 1 into a first chamber 500 containing the pyrotechnic charge and a second chamber 600 traversed by the conductors 6a, 6b and containing the connection piece 700. The piston P is for example retained by notches 300 formed on the internal face of the body 1.

In operation, when the coil 400 is activated, its magnetic field acts on the microswitch M imposing its closed position. The closing of the microswitch M causes the pyrotechnic charge 5 to be heated, and thus the generation of gas. The gases created in the first chamber 500 push the piston P in translation accompanied by the connection piece 700 until it comes to connect the two conductors 6a, 6b. The device may for example provide a valve mechanism 800 for evacuating the combustion gases from the first chamber 500.

It is understood that one can, without departing from the scope of the invention, imagine other variants and refinements of detail and even consider the use of equivalent means.

Claims

1. Device for interrupting / switching on an electric circuit, comprising: a pyrotechnic charge (5) intended to be initiated in combustion to cause the interruption or the engagement of the electric circuit,

- Ignition means for the pyrotechnic charge (5), characterized in that: the ignition means are connected to the electrical circuit, the ignition means comprise a microswitch (M, M ') with magnetic actuation suitable to control the ignition of the pyrotechnic charge (5).

2. Device according to claim 1, characterized in that the microswitch (M, M ') is placed on a circuit branch connected on the one hand to the electric circuit and on the other hand to the ground.

3. Device according to claim 2, characterized in that the ignition means comprises a resistive element (9) heated in series with the microswitch (M, M ') and able to initiate combustion pyrotechnic charge (5). ).

4. Device according to claim 3, characterized in that the microswitch (M ') is controlled by a movable permanent magnet (10).

5. Device according to claim 4, characterized in that the movable permanent magnet (10) is operable in translation.

6. Device according to claim 3, characterized in that the microswitch (M, M ') is controlled by an excitation coil (40, 400).

7. Device according to claim 6, characterized in that the excitation coil (40) is connected in parallel with the electric circuit.

8. Device according to one of claims 1 to 7, characterized in that the electrical circuit comprises two conductors (6a, 6b) and a connecting piece (7) displaceable under the effect of the gases generated by the combustion of the load pyrotechnic.

9. Device according to claim 8, characterized in that the connecting piece (7) initially connects the two conductors (6a, 6b).

10. Device according to claim 6, characterized in that the excitation coil (400) is connected in parallel with the microswitch.

11. Device according to claim 8, characterized in that the excitation coil (400) is controlled by a sensor (C).

12. Device according to claim 10 or 1 1, characterized in that the electric circuit comprises two conductors (6a, 6b) and a connecting piece (700) displaceable under the effect of the gases generated by the combustion of the pyrotechnic charge ( 5).

13. Device according to claim 12, characterized in that the connecting piece (700) is initially disconnected from the two conductors (6a, 6b).

14. Device according to claim 12 or 13, characterized in that the connection piece (700) is integral with a piston (P) separating a first chamber (500) comprising the pyrotechnic charge (5) of a second chamber ( 600) traversed by the two conductors (6a, 6b).

15. Device according to one of claims 1 to 14, characterized in that the microswitch (M, M ') comprises a membrane (20, 20') of ferromagnetic material capable of being controlled between two positions in alignment on the field lines of a magnetic field.