DE29723873U1 - Emergency switch for electrical circuits - Google Patents

Description

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Emergency stop switch - BlattT- KAÖEL-C C GM.DOC

"EMERGENCY SWITCH FOR ELECTRICAL CIRCUITS ¹

The invention relates to a device for the defined and rapid disconnection of electrical high-current circuits in an emergency, which performs its function reliably even after up to 20 years without maintenance and does not represent any additional hazard potential in the form of hot gas, particles, projectiles or high voltages induced in the switched-off circuit.

It is primarily intended for use in automotive engineering for the defined, irreversible disconnection of the on-board wiring from the car battery shortly after an accident in order to avoid ignition sources caused by sparks and plasma, which arise when, for example, cable insulation is chafed by bodywork sheet metal penetrating the vehicle during the accident or loose cable ends swing against each other or against sheet metal parts - especially when petrol leaks out and petrol vapor accumulates under the bonnet, where flammable petrol-air mixtures can form.

Devices used to date, such as the assembly developed and used by DNAG to disconnect the car wiring from the car battery in the event of an accident in order to avoid additional ignition sources for any petrol that may have leaked out and subsequently evaporated, are limited in terms of cutting performance and/or generate such high induced voltages in the separated circuit as a result of the separation process that the electrical devices connected to them are damaged, which is neither permissible nor desirable.

Thus, after being triggered by the airbag sensor, a tool consisting of a combustion chamber and an electrically non-conductive material, which is a conventional force element, presses on the very strongly notched electrical conductor with a cross-section of, for example, 10 mm x 4 mm, whereupon the material of this conductor breaks and the flow of current to the consumers connected to the wiring or to any chafed cable sections is interrupted.

Due to the notching of the material, relatively little force is initially required for separation, but on the other hand, the conductor and thus the current thread breaks off so quickly that

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Emergency switch -blade?- *

very high voltages are induced in the circuit, causing irreversible damage to connected devices and insulation.

Devices for separating power currents with a different design, as is known from high-voltage technology, are not considered here because they are either designed like relays (i.e. in this context the opening of contacts by a magnetic coil or by a small force element, as is already used here and there in overhead line technology) and thus do not even come close to achieving the required reliability after 20 years without a single switch and without maintenance in the mechanical and thermal/climatic environment found in cars, or are simply orders of magnitude too expensive when designed accordingly (the intended module currently has a retail price of around 7 DM) or are simply too heavy and too large - the module is to be used without any structural changes instead of the battery terminal that is common today!

The device disclosed in application no. 19732650.1 already works more reliably and without having to notch the conductor, whereby the conductor cross-section is simply cut off or severed in its entirety by a power cutter.

The invention is based on the object of creating a small and inexpensive assembly of the type mentioned at the beginning, which is able to sever a line section of at least the same size in an autonomous and remote-controlled manner without having to notch the conductor and at the same time not interrupting the flow of current so quickly that the magnetic field generated by the current that may still be flowing in the circuit when the cable is separated does not collapse so quickly and thus induces smaller counter-voltages which, as is well known, tend to delay this field collapse. - This means that the mechanical load-bearing capacity of the conductor can be maintained, as is always desired by all designers, and additional measures to suppress voltage peaks in the cabling and/or in front of the individual electrical consumers can be saved, if that were even possible otherwise!

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Emergency switch -sheet?- * *··"·!.. KAOELC_C_GM.DOC

However, unlike the devices mentioned previously, for the sake of simplicity this is not achieved by mechanically cutting/separating the conductor, but by melting the electrical conductor.

This object is achieved by the features characterized in claim 1. Advantageous embodiments of the invention are characterized in the subclaims.

The main advantage of the invention is that the current interruption is achieved with little destructive effort, whereby the functional reliability increases even further at even lower manufacturing costs.

A further advantage of the invention is the fact that the separation process can now be controlled by the correct choice of the pyrotechnic heating mixture and its combustion or behavior in such a way that the current is no longer switched off so quickly, so that when the current is flowing (and only then do the undesirable voltage peaks occur due to induction) a plasma can form and in this way the otherwise destructive induction energy can be "used up"!

This can be supported by appropriately shaping the cross-section of the conductor to be separated.

The task is achieved in such a way that the energy generated when a thermite mixture burns softens the material of the conductor in seconds so that it can be squeezed out or is simply heated to such an extent that the conductor material melts and drips into the housing, which would then also interrupt the current conduction.

All conductor materials can be used with the device.

The thermite in the cartridge can be ignited by a more powerful pyrotechnic igniter or simply by means of an electrode.

The invention is explained below with reference to the attached 3 figures:

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Emergency stop switch -Sheet '4- ·· KAOELC_C_GM.DOC

Figure 1:

Figure 1 shows the emergency stop switch, consisting of the current-carrying conductor 3, the housing 9 with its reinforcement 16 or 17, the seal 5, the release spring unit 10, the thermite vessel 8, the igniters 7 and the holes 6 possibly filled with pyrotechnic material.

When the igniter 7 is activated, the flame that comes out through the hole 6 or the pyrotechnic mixture that is also ignited there ignites the thermite charges 4. These can be installed as shown here or can fill the entire interior of the housing 9 in order to liquefy the entire conductor. The thermite charges melt the conductor in one long place or two short places so that the conductor is pushed out by the force of the spring unit 10 and the flow of current is interrupted.

Figure 2:

As in Figure 1, except that the thermite charges are ignited by an ignition point, the hole 11 with the pyrotechnic mixture therein takes over the distribution of the outgoing ignition flame.

Figure 3:

Like Figure 1 or 2, only the spring unit 10 is replaced by a pyrotechnic force element which is also controlled by the one pyrotechnic igniter 7 and which consists of the cylinder part 12, the piston part 13 and the propellant powder 15.

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Claims (48)

1. Device for defined and rapid switching of electrical power circuits, characterized in that the conductor ( 3 ) is melted or removed by a pyrotechnic heating element over a longer distance or by two heating elements over a shorter distance in such a way that the conductor can either be pressed out by a spring unit ( 10 ) or is melted directly so that the flow of current is reliably interrupted. 2. Device according to claim 1, characterized in that the pyrotechnic heating element ( 4 ) consists of a thermite. 3. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by an electric igniter or igniter (EED). 4. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a friction- or impact-sensitive igniter or detonator. 5. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a shock tube (TLX, NONEL). 6. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a detonating cord. 7. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a shock wave directly through the conductor with or without a bore ( 6 ). 8. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by an electrode arranged in it upon passage of an ignition current, in particular by an electrode made of a material with only a low electrical conductivity, for example graphite or carbon. 9. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a plate of primary explosive embedded therein, which ignites by a defined impact on the conductor. 10. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is ignited by a plate of primary explosive embedded therein, which is ignited by a laser diode through a hole or an optical window in the wall of the conductor ( 3 ). 11. Device according to claim 1, characterized in that the housing ( 9 ) is protected inside or outside by a reinforcement or insulation ( 16 ) or ( 17 ). 12. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) has an internal structure. 13. Device according to claim 1, characterized in that the pyrotechnic heating mixture ( 4 ) is introduced as a shaped body in the combustion chamber or in the vessels ( 8 ). 14. Device according to claim 1, characterized in that the shaped body made of pyrotechnic heating mixture is pressed or cast into the combustion chamber. 15. Device according to claim 13, characterized in that the shaped body made of pyrotechnic heating mixture has an internal structure. 16. Device according to claim 1, characterized in that each individual heating mixture ( 4 ) is ignited by its own ignition point or its own ignition piece ( 7 ), without or via a bore ( 6 ). 17. Device according to claim 1, characterized in that only one ignition point or only one ignition piece ( 7 ) is used and its output flame is distributed to the individual ignition points via a distributor bore with or without a filling of pyrotechnic material. 18. Device according to claim 1, characterized in that instead of the spring expression system ( 10 ) a pneumatic or hydraulic spring system is used. 19. Device according to claim 1, characterized in that instead of the spring-extrusion system ( 10 ) there is a pyrotechnic force element which can in particular also be controlled by the collecting line ( 11 ). 20. Device according to claim 1, characterized in that the heating mixture ( 4 ) is structurally mounted in such a way that the molten conductor piece is blown off or pressed off by the gas which always occurs during the combustion of the heating mixture. 21. Device according to claim 20, characterized in that the heating mixture contains components which produce increased gas. 22. Device according to claim 1, characterized in that the heating mixture is ignited by a material suitable for this purpose, in particular by metals which are normally stable at the usual temperatures, such as aluminum, magnesium, zirconium or zinc, which are either applied to a surface of an electrically non-conductive, heavily conductive or semi-conductive material in such a way that this layer or conductor track is heated locally or as a whole when current passes through it, so that this material reacts with the oxygen from the air or another introduced oxygen carrier in such a way that it releases exothermic energy, in particular in the form of hot gas and/or hot particles, or is housed in a loading container as a powder or powder compact and from there, after suitable ignition, releases the hot gas or the hot particles to the heating mixture to be ignited. 23. Device according to claim 22, characterized in that this suitable material is aluminium, magnesium, zirconium or zinc. 24. Device according to claim 22, characterized in that said suitable material is an alloy of said metals with each other. 25. Device according to claim 22, characterized in that this suitable material is not pure, but contains other alloy components which are not included in the above list. 26. Device according to claims 22 to 25, characterized in that this ignitable, electrically conductive material or the conductor track formed therefrom is initially applied to or inserted into a carrier plate with an arbitrary shape, but also without this, in particular is designed to be straight and simple, several tracks run parallel or is shaped in a meandering manner. 27. Device according to claim 22 to 26, characterized in that this conductor track is suitably electrically contacted. 28. Device according to claim 22 to 26, characterized in that this conductor track is either applied, painted, pressed or applied by a chemical or chemical-optical process. 29. Device according to claims 22 to 26, characterized in that this conductor track is created by simply scratching, milling or laser ablating an entire layer of this ignitable material once or several times so that glow bridges and thus one or more ignition points are created, in particular in the manner of a ring interrupted once or several times (not shown). 30. Device according to claims 22 to 29, characterized in that the pyrotechnic mixture is ignited by the reaction of an ignition charge which is sensitive to shock or friction and is not electrically ignited by a shock or impact on a pin of the carrier plate or the conductor track carrier itself. 31. Device according to claim 22, characterized in that the ignitable, electrically conductive material of the conductor track is not applied as a more or less wide conductor track, but is accommodated in a pot as a powder, powder compact or as a loose powder, from where the hot gas is then guided through holes in the pot onto the surface of the heating mixture. 32. Device according to claim 31, characterized in that the pot is rod-shaped and is inserted more or less deeply into the heating mixture, whereby the hot gas generated during ignition is injected directly into the heating mixture. 33. Device according to claim 32, characterized in that the holes for the hot gas are arranged in such a way that the ignition and thus the combustion of the pyrotechnic mixture to be ignited can be controlled as desired. 34. Device according to claim 31, characterized in that the powdery ignitable material is itself ignited by the passage of an electric current through a conductor track made of one of these materials. 35. Device according to claim 31, characterized in that the powdery material is ignited by direct passage of current, the electrodes being simply rod-shaped, having surfaces of conductive material on the powder side or being provided with penetrators on the powder side in order to penetrate into the powder body and always establish good electrical contact with it. 36. Device according to claim 31, characterized in that the powdery material is ignited by a filament or a glow wire. 37. Device according to claim 36, characterized in that this filament itself consists of the material described in claim 22, in particular of magnesium, aluminium, zirconium or zinc. 38. Device according to claims 22 to 37, characterized in that the suitable ignitable, electrically conductive material is covered with conventional ignition materials and ignition mixtures or these are mixed with the powder in the pot ( 166 ). 39. Device according to claim 1, characterized in that the heating mixture is ignited by the possible heating of the current conductor itself (automatic shutdown of overloaded current conductors). 40. Device according to claim 1, characterized in that the current conductor itself is designed in such a way that it or in particular at one point is heated by the passage of current in such a way that the heating mixture applied is ignited (automatic shutdown of overloaded current conductors). 41. Device according to claim 1, characterized in that the heating mixture ( 4 ) is ignited by admixing substances which ignite or react at a lower temperature than the heating mixture, in order to be able to use thermite in particular as a heating mixture and to then be able to ignite this by means of the admixed magnesium, zinc, zirconium or aluminum powder. 42. Device according to claim 39, characterized in that these substances which ignite at low temperatures are not mixed into the heating mixture itself, but are only adjacent to it or are located in the vicinity and the hot gases and hot particles generated by them then reach the heating mixture via holes, gaps, openings or pipes. 43. Device according to claim 1, characterized in that the heating mixture is ignited by evaluating a heating of the current conductor, in that the heating is suitably detected, evaluated, converted into a control signal and this is then used to initiate the ignition of the heating mixture. 44. Device according to claim 43, characterized in that the whole is carried out electronically, electro-optically, chemically, pyrotechnically or from a combination thereof. 45. Device according to claim 20, characterized in that the heating mixture ( 4 ) is completely or partially replaced by propellant powder in order to secure or accelerate the blowing out of the conductor to be melted or broken out. 46. Device according to claims 1 to 45, characterized in that the conductor under the heating mixture ( 4 ) or the mixture of heating mixture ( 4 ) and propellant powder or the propellant powder alone (the whole will be referred to in the future only as powder mixture ( 4 )) is weakened or thinned in terms of cross-section as a whole or only in small sections, in particular by narrow but deep cuts in the conductor under and in particular next to the powder mixture ( 4 ), so that less powder mixture ( 4 ) or less propellant powder is sufficient to melt the conductor and in particular to push it off or blow it off. 47. Device according to claims 1 to 46, characterized in that the powder mixture ( 4 ) is in contact (heat conduction) with the conductor in such a way that when the conductor is heated, self-ignition of this powder mixture ( 4 ) is triggered. 48. Device according to claim 47, characterized in that an ignition substance with a very specific ignition temperature is added to the powder mixture ( 4 ) in order to achieve this self-ignition safely and reliably.