EP0973184A1 - Electrical fuse element with fusible strip between connectors - Google Patents

Abstract

The fuse link (2) has fusible conductors (4a, 4b) connected between the mounting section (5) and outer terminals (1a, 1b). The mounting section includes an element (9), for controlled heating.

Description

The invention relates to an electrical fuse element with at least one fuse strip, which is mechanically and electrically connected at both ends to connectors, these parts being made of an electrically conductive material.

Such securing elements are known and serve different purposes. To the Example, one thinks increasingly in the automotive industry about the crash behavior of Vehicles following with the aim of vehicle occupants more or less facing the direct consequences to protect an accident. Among other things, you want a vehicle fire after a collision or avoid another defect. The cause of such a fire can For example, a pinched cable that is still in use when Rescue scissors can be squeezed off and lead to sparking. Therefore one is endeavors to remove essential parts of an electrical system from the energy source (the battery) cut off.

There are already systems with security elements of the type mentioned, with which the electrical connection between the battery and the electrical system is disconnected. Kind of this known systems are the pyrocutter, which are based on pyrotechnic propellants, which drive the battery cable out of the cable lug, detach lines and the like. This Pyrocutter are not reversible to the user of the vehicle, and neither can they being repaired. Disadvantageously, there is also no possibility of emergency operation to carry out, i.e. to bridge a line interruption with an emergency cable and This will restart driving. Apart from the high price one owns Pyrocutter no variability in the sense that such a system is different Vehicle classes could be used interchangeably. Pyrocutter only work and only by an external impulse, so do not switch additionally and independently of this external pulse when high overcurrents occur. Except one is not a disadvantage size to be undercut also the fact that for the production of pyrocutter Explosives must be processed. This requires special conditions in the manufacturing Operation (explosives officer, bunker).

The object of the invention is therefore an electrical fuse element of the beginning to create the type mentioned, which compared to previous shutdown or safety systems is cheaper, lighter and has a more variable function.

This object is achieved according to the invention in that at least one Melting strip at least one with its one outer end with the connector and with its other, opposite end connected to a receiving piece Has fuse element, wherein the receptacle with at least one heating element controlled heating of the receptacle is connected. With these terms it gets away assumed that between the connectors in the simplest case, for example Melting strip is attached, which in the simplest case contains a fusible conductor. With two Fusible conductors connected in series form the aforementioned fusible strips. On A receptacle is connected to one end of a fusible conductor. In the simplest form is the result of the first connector to the second opposite Connector that that on the first connector of the melting strips, be it in Form one or in the form of two fusible conductors, the fusible conductor that Connects receptacle and the second connector is connected to the latter. in the In normal operation, the electrical current flows from the first connector to the Fusible conductor (forming the fusible strip), further over the receptacle and from this in the opposite connector. There is a heating element on the receptacle attached, which is in thermal contact with the receptacle with the result that at Heating the heating element, the receptacle and the adjacent parts of it Fuse element are heated. The heating element is controlled in a controlled manner. This means that of a not described and not shown Evaluation electronics of known type of heating current is sent into the heating element, after a signal has caused the evaluation electronics to emit the heating current.

If a person skilled in the art follows the teaching of the new invention, he will recognize when building the new one Securing element that this not only has a lower weight and is cheaper, advantageously also has a smaller size, but above all has more variable functions.

The new fuse element according to the invention is a fuse with secondary Heat source. If you connect the new fuse element between the positive pole one Energy source, for example a vehicle battery, and a supply line then immediately become apparent the further advantage that the contact resistance to the existing system does not elevated. The resistance of the new element goes to zero. The new security element has an independent fuse element and works autonomously, i.e. it switches in Short-circuit trap automatically with high overload current. This independent function remains also exist if the heating element is not switched on or not heated.

The new securing element has a high degree of variability. It can be characterized by its modular character adjust to different applications. In an extreme special case could by replacing the melting strip (you take a different sheet) Securing element from an application area with few consumers to one easily converted with many consumers.

The use of the heating element attached to the receptacle is advantageous the response of the new security element accelerated considerably. Have attempts shown that compared to normal switch-off times for fuses of around 500 Seconds according to the invention when using the heating element the switch-off time to 50 seconds can be reduced. The self-sufficient safety element can by Newly used heating according to the invention in the area of the receptacle externally can be controlled.

The emergency operation described in connection with the known pyrocutter can be used for perform the new securing element well. In the event of a trigger, only this becomes physical Component itself destroyed, not the entire assembly. Instead of the new securing element can provide a standard backup for emergency operation due to the good accessibility be used.

The material cross section through which the electrical current in the fuse element flows according to the invention, is smaller in the area of the respective fusible conductor than am Connector and also smaller than on the receptacle. The heating element will Receiving piece brought to a higher temperature, and you have lower in the areas Cross-section measured a large temperature gradient and then the desired there Melting of the fuse element found.

Both with overload currents when the new fuse element is self-sufficient, i.e. without outside Signals and works without a heating element, the shutdown is carried out by the basic function undisturbed. Nevertheless, the new security element has the additional function that Heating element can be heated controlled and regardless of the basic function if necessary, an earlier activation of the lines is guaranteed.

The new fuse element is inexpensive for uninterruptible power supplies use, for example in computer systems and also in motor vehicles. Especially at Long lines connected to a battery used to have the problem that a short-circuit current was not generated sufficiently high to a conventional one Get fuses to switch; nevertheless, enough electricity flowed around for example, to set a line on fire. This is suitable for solving these problems new fuse element according to the invention excellent. Even with smaller currents Power lines are now activated, for example in the event of a crash All electronics from the battery are turned off when an error signal warms up of the heating element, because then the new fuse element can be used earlier trigger. Individuals can now use it for new protection concepts in the automotive industry Paths of the entire supply system are monitored and if an error occurs on them Way be turned off.

In an advantageous further embodiment of the invention, the melting strip has at least two fusible conductors, each with its outer end connected to a connecting piece, whose inner end is connected to the receiving piece and the heating element. This Embodiment is a further development of the general version explained above. The teaching of the invention can already be applied if the melting strip has only one If the latter heats up the fuse element with the heating element via the receptacle can be. It has also been shown to be particularly advantageous if the melting strip instead of a fuse element now has two fuse elements, while also a larger number Fusible conductor would be conceivable. The two fusible conductors can be symmetrical on both sides of the Receiving piece be attached so that the heating from the inside, by the heating element over the receptacle to the fuse element located on each of the two sides he follows. This symmetrical structure gives you an even better temperature distribution, and you have a better use of the heating energy than that of the heating element The heat introduced only affects the fuse element. In contrast, could without any special Measures in the general first case with only one fuse element Heat from the receptacle on the side facing away from the fuse element in the Connection piece flow with the possible consequence that the switch-off temperature only a little later is achieved. However, this disadvantage can be avoided if you have a thermal break arranges between the receptacle and the connector, so that by the Heating element generated heat can not escape unhindered to the connector.

With the symmetrical structure with the arrangement of fusible conductors on both sides Each fuse element acts as a thermal brake. So that's a thermal Resistance meant a kind of heat barrier.

It is also advantageous according to the invention if at least two melting strips are parallel connected to each other and connected to two opposite connectors. With these measures, sub-optimization can be achieved. It stands only a little Thermal energy is available and large currents must still be switched off the current flow can be divided, for example, in half, with the result that the first part of the Current through the one melting strip with an intermediate heating element and the other current part flows through the other fusible strip. Is the error signal Evaluation electronics causes a heating current to be released, then the melting strip can switch off in which the heating element is installed. Even if the electricity is there overall flows through the other melting strip, it also switches off because it is not designed for the absorption of the total current. The breaking current can thus be halved of the melt flow can be reduced without a heating element. It is expedient according to the invention even if only one melting strip has a receptacle with a heating element. So if when two melting strips are connected in parallel, for example half the current take over, only one of the two melting strips is connected to the heating element, is sufficient with advantage half the heating output for switching activation. You get one Gain factor. The melt flow is reduced to half.

If, according to the invention, at least one fuse element also has a constriction, the Character of the thermal barrier or thermal barrier by increasing the thermal Resistance increased due to this bottleneck. The effect of the Heating element increases and the response of the fuse element according to the invention be accelerated.

Such a thermal brake could also be used in one or both of the connectors integrate. You could do that, for example, by making a hole or one Effect recess. In effect, you get through these bottlenecks or heat brakes Reduction of the cross section through which the current has to flow. Depending on the application you can optimize the conditions so that enough current through the Securing element flows, but at the narrow point, however, the heat flow in the desired Extent is braked. The fuse element can in an alternative embodiment also be provided with a diffusion agent, for example in the form of a solder bump.

Furthermore, the invention is characterized in that the heating element by friction welding and / or gluing and / or soldering and / or crimping and / or pressure joining and / or Rivets is attached to the receptacle. With such known methods attach the heating element simply and effectively so on the receptacle that a good thermal contact results. These mounting methods and materials prevent one Apply so that the total volume of the heating element can be kept small. Also the effort is low and technically manageable.

Another cheap embodiment is characterized in that the Receiving piece is bent into a U-shape to form a clamping spring such that the heating element is clamped between the legs of the clamping spring of the receiving piece. The Melting strips with attached receptacle, for example, can simply be pulled through Make punching out of a selected sheet. If you then choose the die so that the receptacle is longer than a measure of the heating element, then you can use the heating element by folding the receptacle practically "wrap" it in this. The recording piece can be bent in a U-shape so that the two legs of the U press against each other. A heating element can be easily clamped in such a spring in this way and hold on. It can also be beneficial if you add in addition to the clamp connection the manner just described adhesive, soldering materials and the like for holding the Heating element used on the receiving piece. With the right choice of materials the thermal resistance between the heating element and the receptacle can be greatly reduced. It is important to achieve the lowest possible heat transfer resistance between Heating element and receptacle, the type of contact should be as positive as possible.

It has proven to be advantageous if, according to the invention, the heating element is plate-shaped and has a layer structure with a base layer made of ceramic, with an electrical heatable heat conductor layer made of platinum and a cover layer made of ceramic. On a Base layer made of ceramic, a platinum plate can be placed, from which by means of laser beams Areas are burned out so that a kind of platinum heating coil is created. It it goes without saying that one end of this helix with the feed wire and the other with the Leakage wire for electrical current is connected. This heating current is from a Evaluation electronics supplied, which evaluates a signal and the delivery of the heating current concerned.

The evaluated signal can be derived from any physical quantity. It can come from the heating element itself, for example. By the current flow through the The securing element heats up the receiving piece and therefore the heating element. One grabs a corresponding voltage on the connecting or supply wires of the heating element from, which is calibrated, for example, to a current flow through the fuse element, then the evaluation electronics are already available when a certain current flow is exceeded Have the additional current given off for the heating element. The result is an accelerated one Switch off the fuse element. The heating element in the fuse according to the invention can also be used as an information provider to by electricity and / or Temperature information to tell the user - with the help of the heating element - which one Current flows between the connectors.

In a motor vehicle, maximum currents can be set for certain consumers are that must not be exceeded, otherwise the securing element according to the Should trigger invention. In its basic function, the securing element can be a Tripping current need that can be greater than a fault current. A conventional one Fuse would then occur if only the error signal or only a small overcurrent do not trigger. Due to the error signal, the evaluation electronics are used to trigger the Heating current causes, but is advantageous according to the invention for the use of the additional function ensured that the system is unlocked.

Figur 1

die Draufsicht auf den Schmelzstreifen mit zwei Anschlußstücken für ein elektrisches Sicherungselement gemäß einer ersten Ausführungsform der Erfindung,

Figur 2

eine Querschnittsansicht entlang der Linie II-II der Figur 1,

Figur 3

im Querschnitt den Schichtenaufbau einer besonderen Ausführungsform eines Heizelementes,

Figur 4

eine Draufsicht auf das Heizelement gemäß Figur 3, wenn man dort von oben nach unten blickt,

Figur 5

eine ähnliche Ansicht wie Figur 1, jedoch von einer anderen Ausführungsform, bei welcher zwischen zwei Anschlußstücken zwei parallel zueinander liegende (elektrisch geschaltete) Schmelzstreifen angeordnet sind, und

Figur 6

eine ähnliche Ansicht wie Figur 5, jedoch von einer weiteren anderen Ausführungsform, bei welcher das Aufnahmestück nicht in einem der zwei parallelgeschalteten Schmelzstreifen sondern dazwischen angeordnet ist, nämlich auf einem Verbindungsstück zwischen den zwei parallelen Schmelzstreifen.

Further advantages, features and possible applications of the present invention result from the following description of preferred embodiments in conjunction with the attached drawings. These show:

Figure 1

the top view of the fusible strip with two connectors for an electrical fuse element according to a first embodiment of the invention,

Figure 2

2 shows a cross-sectional view along the line II-II in FIG. 1,

Figure 3

in cross section the layer structure of a special embodiment of a heating element,

Figure 4

3 shows a top view of the heating element according to FIG. 3 when one looks down there from above,

Figure 5

a view similar to Figure 1, but of another embodiment, in which two parallel (electrically connected) melting strips are arranged between two connectors, and

Figure 6

a view similar to Figure 5, but of a further different embodiment, in which the receiving piece is not arranged in one of the two parallel melting strips but in between, namely on a connecting piece between the two parallel melting strips.

The outer functional parts of an electrical fuse element are the connectors 1a, 1b, which are shown in plan view in Figures 1, 5 and 6. In between is in the embodiment of Figure 1, a single melting strip 2, while in the Embodiments according to FIGS. 5 and 6 each have two melting strips 2a and 2b in between. The length of each melting strip, 2, 2a, 2b is equal to the distance of the straight edges 3 of the two connectors 1a, 1b from each other.

In the embodiment of FIG. 1, the fusible strip 2 has two fusible conductors 4a, 4b on. In between is a receiving piece 5, which according to the cross-sectional view 2 is bent into a U-shape. The lower leg of the U is 6 and the upper leg is 7 designated. Both legs 6, 7 form a through the correspondingly sharply curved web 8 Clamping spring.

From the open side of this clamping spring 6-8, a heating element 9 is inserted and between the legs 6 and 7 of the receptacle 5 clamped. About additional used Glue or solder material to further reduce the heat resistance is not shown. At the connection points 10a and 10b there are interfaces via connecting lines 11a and 11b are provided. Those shown in between in Figures 1, 5 and 6 Interfaces 12a and 12b are connected to the heating conductor layer denoted by 13. If you use the heating element 9 as a temperature sensor on the one hand and you measure between the Interfaces 11a and 11b, on the other hand, the voltage drop during operation when current from the one connector 1a flows to the other connector 1b, then allows recycling both signals to determine the current flowing through the melting strip 2.

In another application, the interfaces 12a and 12b cannot with one shown evaluation electronics are connected, which after receiving a signal Heating current through the lines denoted by 14 in Figures 3 and 4. The Layer structure of the heating element 9 can be seen from FIG. 3, namely the lower one Base layer 15 made of ceramic, the overlying heat conductor layer 13 made of platinum and the applied cover layer 16 made of ceramic, which for fixing the lines 14 to the the respective platinum conductor.

This heating element 9 has a plate shape, which is why it is good on a flat surface Attach receptacle 5 and there in the embodiment shown here by Clamp spring 6 - 8 can be clamped.

In the embodiment shown here, the melting strips form with the connecting pieces a flat metal structure. But you can also imagine non-flat parts that are electrically connected to each other. Instead of metals, such as copper sheets or silver sheets, you can also doped for individual components of the fuse element Introduce semiconductor elements or other electrically conductive materials.

In the embodiment of FIG. 5 there is another parallel to the melting strip 2a (above) Melting strips 2b (below) are arranged and each with the connecting pieces 1a and 1b connected. Only the lower melting strip 2b has the receiving piece 5 between two Fusible conductors, like the upper fusible conductors with 4a (left) and 4b (right) of the Recording piece 5 are designated. All fusible conductors 4a, 4b can be straight or curved bars with continuous, straight edges. In the embodiments shown here but semicircular recesses are made in the edges, through which there is a constriction 17 in each case.

In the embodiment of FIG. 6b, the arrangement of the melt strips 2a and 2b is that same as in the embodiment of FIG. 5. The lower melting strip 2b has but not even a receptacle 5 with heating element 9. Rather, the middle ones Areas of the two melting strips 2a and 2b by an additional, transverse to the Melting strip connecting piece 18 connected. This connector 18 has in this embodiment the receiving piece 5 with the heating element 9. The Function is corresponding, with the respective fusible conductor in the region of its constriction 17 melts first.

Claims (8)

Electrical fuse element with at least one fusible strip (2) which is mechanically and electrically connected at both ends to connecting pieces (1a, 1b), these parts (2, 1a, 1b) being made of an electrically conductive material, characterized in that at least the a fusible strip (2, 2a, 2b) has at least one fusible conductor (4a, 4b) connected with its one outer end to the connecting piece (1a, 1b) and with its other, opposite end to a receiving piece (5), the receiving piece ( 5) is connected to at least one heating element (9) for the controlled heating of the receiving piece (5). Securing element according to claim 1, characterized in that the melting strip (2) at least two each with its outer end with a connector (1a, 1b) connected fusible conductors (4a, 4b), the respective inner End is connected to the receiving piece (5) and the heating element (9). Securing element according to claim 1 or 2, characterized in that at least two melting strips (2a, 2b) connected in parallel to one another and to two opposite connectors (1a, 1b) are connected. Securing element according to one of claims 1 to 3, characterized in that only one melting strip (2b) has a receiving piece (5) with heating element (9). Securing element according to one of claims 1 to 4, characterized in that at least one fuse element (4a, 4b) has a constriction (17). Securing element according to one of claims 1 to 5, characterized in that the heating element (9) by friction welding and / or gluing and / or soldering and / or Crimping and / or pressure joining and / or rivets attached to the receiving piece (5) is. Securing element according to one of claims 1 to 6, characterized in that the receiving piece (5) is bent in a U-shape to form a clamping spring (6, 7, 8), that the heating element (9) between the legs (6, 7) of the clamping spring (6 - 8) of the Receiving piece (5) can be clamped. Securing element according to one of claims 1 to 7, characterized in that the heating element (9) is plate-shaped and has a layer structure with one Base layer (15) made of ceramic, with an electrically heatable heat conductor layer (13) made of platinum and with a cover layer (16) made of ceramic.

Images