DE202010014430U1 - Overvoltage protection element and electrical device - Google Patents

Abstract

Device for overvoltage protection with a housing (2), with at least one overvoltage limiting component (3) arranged in the housing (2), in particular a varistor or a gas-filled surge arrester, and with two connection elements (4, 5) for electrical connection of the overvoltage protection element (1 ) to the protected power or signal path, wherein in the normal state of the overvoltage protection element (1), the connection elements (4, 5) each with a pole of the overvoltage limiting component (3) are in electrically conductive contact, characterized in that within the housing (2 ) a thermally expandable material (6) is arranged such that upon thermal overloading of the overvoltage limiting component (3, 3 ') the position of the overvoltage limiting component (3, 3') due to expansion of the heat expandable material (6) relative to the position of the terminal elements ( 4, 5) is variable so that at least ei n pole of the overvoltage limiting component (3, 3 ') is no longer in electrical contact with the corresponding connection element (4, 5).

Description

The invention relates to an overvoltage protection element and an electrical device in which an electrical connection by means of a heat-expandable material from a first to a second position can be brought.

From the DE 42 41 311 A1 is an overvoltage protection element is known, which has a thermal separation device for monitoring the state of a varistor. In this overvoltage protection element, the first connection element is connected via a flexible conductor to a rigid separation element whose end remote from the flexible conductor is connected via a solder joint to a connection lug provided on the varistor. The other connection element is connected via a flexible conductor fixed to the varistor or a terminal lug on the varistor. The separating element is acted upon by a spring system with a force which results in the separating element being linearly moved away from the connecting lug during the separation of the soldering connection, with the result that the varistor is electrically cut off in the event of thermal overloading. By means of the spring system, a remote signaling contact is actuated at the same time during the separation of the solder connection, whereby a remote monitoring of the state of the overvoltage protection element is possible.

Also from the DE 20 2004 006 227 U1 an overvoltage protection element is known, in which the monitoring of the state of a varistor according to the principle of a temperature switch, so that when overheating of the varistor a provided between the varistor and a separator solder joint is separated, resulting in an electrical separation of the varistor. In addition, when separating the solder joint, a plastic element is pushed by the restoring force of a spring from a first position to a second position in which the formed as a resilient metal tongue separating element is thermally and electrically separated from the varistor by the plastic element, so that a possibly between the metal tongue and the contact point of the varistor arcing arc is deleted. Since the plastic element has two color markings arranged next to one another, it additionally acts as an optical status indicator, as a result of which the state of the overvoltage protection element can be read directly on site.

From the DE 699 04 274 T2 An overvoltage protection element with a thermal cutoff mechanism is also known. In this overvoltage protection element, one end of a rigid spring-loaded slider in the normal state of the overvoltage protection element is soldered both to the first connection element and to a connection lug connected to the varistor. An inadmissible heating of the varistor also leads here to a heating of the solder joint, so that the slider is pulled due to the force acting on it a spring from the junction between the first terminal and the terminal lug, resulting in an electrical separation of the varistor.

The DE 695 03 743 T2 discloses an overvoltage protection element with two varistors, which has two separating means, which can individually separate the varistors at their end of life. The separating means each have a resilient separating tongue, wherein the first end of the separating tongue firmly connected to the first terminal and the second end of the separating tongue is attached in the normal state of the overvoltage protection element via a solder joint to a connecting tongue on the varistor. If there is an inadmissible heating of the varistor, this leads to a melting of the solder joint. Since the separation tongue is deflected in the soldered state (normal state of the overvoltage protection element) from its rest position and thus biased, the free end of the separation tongue springs when softening the solder joint of the connecting tongue of the varistor, whereby the varistor is electrically disconnected. In order to ensure the required insulation and tracking resistance and to erase an emerging when opening the separation point arc, it is necessary that the greatest possible distance between the second end of the separation tongue and the connecting tongue of the overvoltage limiting component is achieved when pivoting the separation tongue.

The known overvoltage protection elements are generally designed as a "protective plug", which together with a device lower part form an overvoltage protection device. To install such a surge protection device, which is intended to protect, for example, the phase-leading conductors L1, L2, L3 and the neutral conductor N and possibly also the earth conductor PE, corresponding terminals for the individual conductors are provided in the known surge protection devices on the device base. For simple mechanical and electrical contacting of the device base with the respective overvoltage protection element, the connection elements are designed as plug pins in the overvoltage protection element, which are arranged in the lower device part corresponding, connected to the terminals sockets, so that the overvoltage protection element can be easily plugged onto the device base.

In such overvoltage protection devices installation and assembly is through the Plugability of the surge protection elements very simple and time-saving feasible. In addition, such overvoltage protection devices partly still have a changeover contact as a signal transmitter for remote signaling of the state of at least one overvoltage protection element as well as an optical status indication in the individual overvoltage protection elements. The status display indicates whether the overvoltage-limiting component arranged in the overvoltage protection element is still functional or not. In particular, varistors are used as overvoltage limiting component, although it is also possible to use gas-filled surge arresters, spark gaps or diodes depending on the intended use of the overvoltage protection element.

The above-described, used in the known overvoltage protection elements, thermal separation devices, which are based on the melting of a solder joint, have to fulfill several tasks. In the normal state of the overvoltage protection element, d. H. in the non-separated state, a secure and good electrical connection between the first connection element and the overvoltage limiting component must be ensured. When a certain limit temperature is exceeded, the separation point must ensure a safe separation of the overvoltage limiting component as well as a permanent insulation resistance and tracking resistance. The problem is, however, that the solder joint is permanently loaded with a shear stress due to the spring force of the spring element or deflected from its rest position separating tongue in the normal state of the overvoltage protection element.

The object of the present invention is therefore to provide an overvoltage protection element as described above in which the abovementioned disadvantages are avoided. In this case, both a safe and good electrical connection in the normal state and a safe separation of a defective or heated overvoltage limiting component should be ensured.

This object is achieved in the above-described overvoltage protection element in that within the housing, a thermally expandable material is arranged such that upon thermal overload of the overvoltage limiting component, the position of the overvoltage limiting component due to an expansion of the heat-expandable material relative to the position of the connecting elements is variable so that at least one pole of the overvoltage limiting component is no longer in electrically conductive contact with the corresponding connection element.

The heat-expandable material, which is preferably composed of a low-melting plastic, for example polyethylene (PE) or polypropylene (PP), and a propellant is in the normal state of the overvoltage protection element in a solid state. As the temperature of the heat-expandable material increases due to increased heating of the over-voltage limiting device, the heat-expandable material changes state of aggregation and becomes liquid. After exceeding a certain threshold temperature, the heat-expandable material reacts with a large volume increase; the heat-expandable material foams up. This caused by the increase in temperature large increase in volume of the heat-expandable material is used in the overvoltage protection element according to the invention to move the overvoltage limiting component away from the connection elements, so that the overvoltage limiting component is electrically separated or short-circuited.

Since the heat-expandable material only with a corresponding heating, d. H. upon thermal overloading of the overvoltage limiting device, is activated and expands, the electrical contact between the terminal elements and the poles of the overvoltage limiting device in the normal state is not mechanically stressed by the heat-expandable material.

According to one embodiment of the overvoltage protection element according to the invention, the electrical contact between the connection elements and the poles of the overvoltage limiting component - as basically known from the prior art - realized via a solder joint. For this purpose, in the normal state of the overvoltage protection element, the poles of the overvoltage limiting component are each connected to the connection elements via a solder joint. In this case, the solder joint then disconnects when the temperature of the overvoltage limiting component exceeds a predetermined limit temperature at which the force acting on the overvoltage limiting component by the expanding heat-expandable material is greater than the remaining holding force of the solder joints.

According to a preferred embodiment of the overvoltage protection element according to the invention, however, a shock current carrying plug connection is provided instead of a solder joint. For this purpose, in the normal state of the overvoltage protection element both poles of overvoltage limiting component connected via a respective plug connection with a connection element. In this case, the heat-expandable material arranged inside the housing assumes both the function of a sensor, which detects an inadmissible heating of the overvoltage-limiting component, and the function of an actuator, which moves the overvoltage-limiting component away from the connection elements under thermal overload. In contrast, in the known overvoltage protection elements, which are based on the melting of a solder joint, the function of the sensor of the solder joint and the function of the actuator of the spring or the deflected from his Ruhrlage release agent is taken.

In principle, it is also possible for one pole of the overvoltage limiting component to be connected to a connection element via a soldering point, while the other pole is connected to the second connection element for example via a plug connection or a flexible conductor. Likewise, it is also possible that in the normal state of the overvoltage protection element, one pole of the overvoltage limiting component is connected via a plug connection with a connection element, while the other pole is connected via a flexible conductor to the other connection element. If one pole of the overvoltage-limiting component is connected to a connection element via a flexible conductor, this will result in only one pole no longer being in electrically conductive contact with the corresponding connection element during the change in position of the overvoltage-limiting component due to the expansion of the heat-expandable component nevertheless causes the overvoltage limiting device to be electrically disconnected.

Advantageously, the overvoltage protection element according to the invention, however, is designed so that when thermal overload of the overvoltage limiting component both poles are separated from the connection elements, so that after the separation of both poles of overvoltage limiting device with the connection elements are no longer in electrical contact. The formation of two separation points the extinction of a possibly occurring arc is favored because the two separation points form a series connection, so that increases the total arc length and thus the arc voltage by the series connection of the two separation points. It is advantageous if - as previously stated - both poles of Überspannungsbgerenzenden device via a respective plug connection with a connection element are connected, since then the separation of the electrical connection primarily of the temperature behavior of the heat-expandable material and not (also) of the Separation behavior of a solder joint depends.

According to a further advantageous embodiment of the overvoltage protection element according to the invention, the two poles of the overvoltage limiting component are each electrically connected to a terminal lug or a pin. Due to the design of the terminal lugs or pins, both the solder joints and the connections between the poles of the overvoltage limiting component and the connection elements can be realized easily. In the first case, the solder joints are each provided between a connecting lug or a connecting pin and a connecting element while, in the case of a plug connection, the connecting elements have plug sockets on the side facing the connecting lugs or the connecting pins.

According to an advantageous structural embodiment of the invention, the housing has an outer housing and a housing disposed in the outer housing, on one side open inner housing, wherein the inner housing is displaceable relative to the outer housing. The connection elements are fixedly connected to the outer housing, while the surge-limiting device is disposed within the inner housing. In the normal state of the overvoltage protection element, the hood-shaped inner housing encloses the heat-expandable material in such a way that the inner housing with the overvoltage-limiting component is displaced relative to the outer housing, and thus also to the two connection elements, upon expansion of the heat-expandable material. Heating of the overvoltage-limiting component activates the heat-expandable material and thus forces the inner housing together with the overvoltage-limiting component arranged therein away from the connection elements so that the poles of the overvoltage-limiting component are no longer in electrically conductive contact with the connection elements.

To ensure that with a displacement of the inner housing and the overvoltage limiting component is moved, this is preferably connected via a holding element with the inner housing. In this case, the retaining element can be configured, for example, in the manner of a web and fastened by its two ends to the inner wall of the housing so that it extends in the transverse direction of the overvoltage-limiting component.

According to a preferred embodiment of an overvoltage protection element according to the invention with an outer housing and an inner housing displaceably arranged in the outer housing, the change in position of the inner housing is used for optical indication of the state of the overvoltage limiting component. For this purpose, the inner housing is arranged in the normal state of the overvoltage protection element in its first position within the outer housing so that the upper side of the inner housing does not protrude beyond the upper side of the outer housing. On thermal overloading of the overvoltage protection element, on the other hand, due to the expanding thermally expandable material, the inner housing is displaced to a second position, in which the upper side of the inner housing projects beyond the upper side of the outer housing. The displacements of the inner housing in case of thermal overload of the overvoltage protection element is thus used to display the functional status of the overvoltage protection element.

According to an alternative constructive embodiment of the overvoltage protection element according to the invention, the housing has two electrically insulated holding elements, wherein in the normal state of the overvoltage protection element, the holding elements are each in electrical contact with a pole or a connecting pin or a connecting lug of the overvoltage limiting component. In this case, the holding elements enclose the heat-expandable material, so that the overvoltage-limiting component is displaced relative to the holding elements in the event of unacceptable heating by the activated heat-expandable material. The overvoltage limiting component is then no longer in electrically conductive contact with the holding elements and is electrically disconnected. In this embodiment variant, the electrically conductive holding elements serve both as a housing for receiving the overvoltage limiting component and the heat-expandable material and as connecting elements for the electrical connection of the poles of the overvoltage-limiting component.

The electrically conductive contact between the poles or connected to the poles connecting tabs or pins of the surge arrester and serving as connecting elements holding elements can be realized both via a solder connection and via a plug connection, wherein in the realization of a connector in the connection region of the holding elements the connector tabs or the connector pins corresponding sockets can be arranged. Such an overvoltage protection element is particularly suitable when using a gas-filled surge arrester as overvoltage limiting component, wherein the surge arrester can be connected via the two holding elements, for example with a printed circuit board.

Depending on the configuration of the holding elements and depending on the arrangement of the overvoltage limiting component and the heat-expandable material between the holding elements, the overvoltage limiting component is pressed by thermal expansion of the expanding heat-expandable material either upwards - perpendicular to its longitudinal extent - or horizontally to the side. Of course, a configuration is possible in which the overvoltage limiting component is pressed by the expanding heat-expandable material both upwards and to the side. In all cases, the expansion of the heat-expandable material and the consequent change in position of the overvoltage-limiting device ensure that the poles of the overvoltage-limiting device are no longer in electrically conductive contact with the holding elements.

In order to ensure a high insulation and tracking resistance and to erase a resulting when opening the contacts between the poles of the overvoltage limiting component and the connecting elements arc, the largest possible distance between the poles or the terminal straps of the overvoltage limiting component and the Connection elements can be achieved. In the case of the overvoltage protection element according to the invention, according to an advantageous embodiment, the heat-expandable material penetrates into the interstice between the at least one pole or the one terminal lug or the one connection pin of the overvoltage-limiting component and the at least one connection element in the event of thermal overloading of the overvoltage-limiting component, so that an electric arc resulting from the separation of the electrical contact is cut off by the insulating heat-expandable material. Alternatively or additionally, at least one plastic part, for example made of POM, may be arranged in the region of the connection elements, which is gassing when heated. If an arc occurs in the vicinity of the plastic part, it is extinguished by blowing with an extinguishing gas, which is generated by the dissociation of the plastic part.

According to a last advantageous embodiment of the overvoltage protection element according to the invention, which will be briefly mentioned here, Alternatively, or in addition to the above-described optical status indication, there is provided a remotely transferable status indication, within which a telecommunications contact is located within the housing, which is actuated when the position of the overvoltage limiting component changes due to the expanding heat expansible material.

Electrical or electronic equipment often has components that are subject to potential overloading. An overload that damages or destroys the component or the electrical or electronic device can be caused by various unforeseeable events. For example, a defect of a upstream or downstream device or another device electrically connected to the device concerned lead to an inadmissibly high power consumption in the affected device, caused by an excessive voltage applied or too large current flowing through the device current. Likewise, by improper use or by incorrect installation of an electrical or electronic device, an overload of the device or a device arranged in the device can be caused. The resulting high power conversion leads to an increasing self-heating of the device, which can eventually lead to ignition of the device and thus the entire device, so that an unacceptably high power conversion in an overloaded device represents an acute fire hazard.

The danger of a fire of an electrical or electronic device can also be caused by the aging process of certain electronic components. Towards the end of the life cycle, with certain electronic components, for example semiconductors, a progressive decrease in impedance can take place, so that increasingly leakage currents can occur which can lead to self-heating of the component concerned. The self-heating and the increased leakage current can additionally accelerate the aging process of the component.

For this reason, so-called temperature fuses or thermal fuses are used in electrical and electronic equipment in which there is a fire risk, the object is to switch off the power supply of the device at too high a monitored component temperature, so that a further self-heating of the device and the resulting fire hazard is prevented.

Such thermal fuses usually consist of a housing in which two wires are arranged, which protrude on one side of the housing as connecting wires from the housing. Inside the housing, the two wires are electrically connected to each other via a generally horizontally arranged conductive connecting web, for which purpose the connecting web is soldered at its two end regions in each case with a wire. Below the connecting web, a spring element is arranged, which presses in the normal state of the thermal fuse against the connecting web. The spring element causes a lifting of the connecting web of the two connecting wires and thus an interruption of the conductive connection when the solder joints between the connecting web and the two wires due to heating no longer can muster the required counterforce to the spring force of the spring element.

Such a thermal fuse is also from the DE 10 2005 045 778 A1 known. This temperature fuse has a conductor bar which electrically conductively connects two sections of a current-carrying conductor in the normal state of the temperature fuse by the conductor bar being connected to the ends of the two conductor sections via a respective solder connection. In the event of a thermal fault, the electrical connection between the conductor bar and the two conductor sections is separated by an opening element, which may, for example, be a prestressed spring element. In the normal state of the thermal fuse, the spring element is locked by a holding element, the material of which mechanically yields when the critical temperature is exceeded, so that the mechanically prestressed spring element lifts off the conductor bar from the ends of the conductor sections.

According to another embodiment of the known thermal fuse is used as the opening element, a cylinder with a piston. In the event of a thermal fault, an electrical activation of the piston takes place in such a manner that the conductor step is lifted off the two conductor sections by a protrusion of the piston and thus the electrical bridge realized via the soldering connections is separated.

The disadvantage of a conventional thermal fuse, in the normal state, a spring element permanently presses against the connection, is that thereby the solder joints between the connecting step and the leads are permanently mechanically stressed. This disadvantage is at the out of the DE 10 2005 045 778 A1 Although known temperature fuse avoided in this Temperature fuse, however, the structure of the opening element with an additional holding element or a required electrical circuit for driving a piston is much more expensive.

The present invention is therefore also an object of the invention to provide an electrical device that responds reliably with the simplest possible structure to the overloading and aging of electronic components in electrical or electronic devices, so that an unacceptably high power conversion detected in the monitored component and appropriate security measures can be triggered.

This object is achieved in the electrical device described above in that within the housing, a heat-expandable material is arranged such that the connecting member by the heat-expandable material from a first position can be brought into a second position when the heat-expandable material due to activation above a certain activation temperature expands. In this case, either in the first position or in the second position of the connection component, the second ends of two conductor sections are in electrical contact with the connection component, so that these two conductor sections are electrically connected to one another via the connection component. In the electrical device according to the invention, the heat-expandable material arranged inside the housing assumes both the function of a sensor, which detects an inadmissible self-heating of a component to be monitored, and the function of an actuator, which spends the connection component from its first position to a second position.

The heat-expandable material, which is made of, for example, a low-melting material, such as a plastic, e.g. As polyethylene (PE) or polypropylene (PP), and a propellant is in the normal state, d. H. in the normal operating state of the component to be monitored, in which this has no elevated temperature, in a solid state. As the temperature of the heat-expandable material, e.g. B. due to increased self-heating of the monitored component, the heat-expandable material changes its state of aggregation and becomes liquid. After exceeding a certain temperature, the heat-expandable material reacts with a large volume increase; z. B. Foams the heat-expandable material. This large increase in volume of the heat-expandable material caused by the rise in temperature is used in the electric device according to the invention to transfer the connecting component from a first position to a second position.

In one embodiment, the particular activation temperature of the heat-expandable material is above 80 ° C, especially above 120 ° C.

In another embodiment, the heat-expandable material has a volume increase of at least twice the initial volume before activation.

In yet another embodiment, the heat-expandable material has a response time of less than 1 second for activation.

According to another embodiment of the invention, the heat-expandable material comprises a thermoplastic carrier.

The heat-expandable material may comprise, for example, a thermoplastic polymer-based carrier selected from the group consisting of: acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylacetate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PC). PET), polyolefins, such as. Polyethylene (PE), polypropylene (PP), polyisobutylene (PIB), polybutylene (PB), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), polybutylene terephthalate (PBT) and celluloid, or the irreversible thermally expandable material an elastomer having a Shore A hardness of less than 20 as a carrier.

According to yet another embodiment, the activation by external energy input, z. B. in case of error, causes. External energy input can also be introduced by means of a heat pipe or by a corresponding heat conductor.

In a further embodiment of the invention, the activation is effected by a resistance heating element, wherein the resistance heating element is connected to the circuit.

In yet another embodiment of the invention, the heat-expandable material comprises microspheres.

Furthermore, in a further embodiment it is provided that the heat-expandable material comprises a blowing agent and carrier, wherein the activation temperature of the blowing agent is lower than the softening temperature of the carrier material.

Furthermore, in yet another embodiment, the heat-expandable material comprises a propellant and carrier, wherein the activation temperature of the propellant is higher than the softening temperature of the carrier material.

In another embodiment, the heat-expandable material comprises an irreversibly heat-expandable material.

According to yet another embodiment, the device is a structural unit.

The thermal expansion of the propellant is generally irreversible.

By suitable selection and arrangement of propellant material and carrier material, however, it can be achieved that the carrier material, upon cooling, returns the propellant to its initial state, ie. H. into the normal state, transferred.

Such thermally expandable materials are generally referred to as intumescent materials. This thermal expansion is to be distinguished from the normal thermal expansion of a material.

Because the heat-expandable material does not expand until it heats up, i. H. extends in the thermal fault, the electrical contact between the connecting member and the second ends of the conductor sections in the normal state is not mechanically stressed by the heat-expandable material. In addition, the use of a retaining element or a circuit for activating the heat-expandable material is not required.

According to a first embodiment of an electrical device according to the invention with two conductor sections, the two conductor sections in the first position of the connection component are electrically connected to one another via the connection component, while the two conductor sections are insulated from one another in the second position of the connection component by the heat-expandable material. If the connecting component is a conductive contact plate or a conductive connecting web, the device represents a switch in the form of an opener.

Such an electrical device can be used, for example, as a temperature fuse, for which purpose the device must be arranged in the vicinity of the component to be monitored so that self-heating of the component to be monitored from the heat-expandable material is detected, ie. H. can lead to a corresponding heating of the heat-expandable material. By interrupting the conductive connection of the two conductor sections via the connection component, the electrical energy supply of the monitored component can be interrupted from reaching a critical temperature, so that ignition of the device and thus also ignition of an electrical or electronic device, in which the device to be monitored is arranged, can be prevented.

According to an alternative embodiment, the device may also have the function of a closer, in which case the two conductor sections are not electrically connected to each other in the first position of the connecting member, while the conductor sections are electrically connected to each other in the second position of the connecting member via the connecting member. For example, with such a normally-open switch or electrical device, when the self-heating of the device causes the activation temperature of the heat-expandable material to reach such that the heat-expandable material expands, thereby expanding the connection component into the second Position moves.

According to a further alternative embodiment of the electrical device according to the invention, which has a first pair of conductor sections assigned to one another and a second pair of conductor sections assigned to one another, in the first position of the connection component, the two conductor sections of the first pair are electrically connected to one another via the connection component, while the two conductor sections of the second pair are not electrically connected to each other. In the second position of the connecting member, however, the two conductor portions of the second pair are electrically connected to each other via the connecting member, while the two conductor portions of the first pair are not electrically connected to each other. When the connecting component is brought from its first position to its second position by the expansion of the heat-expandable material, this thus leads to a switching over of two contacts, wherein in the first position of the connecting component the two conductor sections of the first pair and in the second position of the connecting component two conductor portions of the second pair are electrically connected to each other via the connecting member. Instead of the formation of four individual conductor sections, only three individual conductor sections may be provided, in which case a conductor section is assigned to both the first pair and the second pair.

If a conductive contact plate or a conductive connecting web is used as the connecting component, then the electrical device according to the invention represents a switch whose switch position as a function of the temperature of a to be monitored component is changed. Depending on the arrangement of the connection component and depending on the number of conductor sections present, an electrical device formed in this way may, as described in detail above, have the function of an opener, a make contact or a changeover switch.

According to an alternative embodiment of the electrical device according to the invention, the connection component can also be an electrical or electronic component, for example a resistor or a semiconductor component, or an overvoltage protection element, for example a gas discharge tube. In this case, it is then preferably provided that the connecting component is in electrical contact with the second ends of two conductor sections in its first position. Expansion of the material due to heating of the heat-expandable material then causes the electrical contact between the connection member and the conductor portions to be disconnected, i. H. the connection component is electrically disconnected.

Such an electrical device can then also be used to arrange a connection component arranged in the housing, for example a semiconductor component or an overvoltage protection element, which is in electrical contact with the second ends of the two conductor sections in the normal state, itself from excessive self-heating due to overloading or To protect a too large leakage current. The overloaded connection member disposed in the housing is then separated from the conductor sections by the expanding thermally expandable material, i. H. the flow of current through the connection component is interrupted. In this case, the electrical device is not used to detect the inadmissible heating of another component, but to detect the inadmissible heating of the arranged in the housing of the electrical device device and its shutdown to ignite the device - and thus the electrical device - to prevent.

According to a preferred embodiment of the electrical device, which may be provided independently of how the connection component is formed, the electrical device has an optical status display, for which purpose a viewing window is formed in one side of the housing. According to a first embodiment, the housing is dimensioned such that the viewing window is arranged so that the connecting member is located in its second position below the viewing window, while the connecting member is arranged in its first position spaced from the viewing window. The displacement of the connecting component can thus be used to display the functional status of the electrical device or a monitored component.

According to an alternative embodiment, the viewing window is arranged in the housing such that the heat-expandable material is arranged in the expanded state below the viewing window, so that it can be seen through the viewing window. In this case, the heat-expandable material is preferably colored, for example colored reddish, so that by looking at the viewing window for the user is easily recognizable when the heat-expandable material has expanded. In this embodiment, the expansion of the heat-expandable material itself is used to indicate the functional status of the electrical device or a monitored device.

As an alternative or in addition to the above-described optical status display, the electrical device may also have a remotely transferable status indication, within which a telecommunications contact is arranged within the housing, which is activated when the connecting member is moved from the first position to the second by the expanding heat expansive material Position has moved or moved. Depending on the arrangement of the telecommunications contact within the housing, this is thus actuated either only when the connecting member is in the second position, or already at a slightly earlier time when it is moved from the first position to the second position.

In addition to the electrical device described above, the invention also relates to the use of a heat-expandable material as a functional material for detecting an improper heating of an electrical or electronic device due to overloading or aging of the device, wherein the heat-expandable material expands when heated above a certain activation temperature and the expansion of the heat-expandable material causes the component's electrical energy supply to be interrupted or short-circuited.

Heat-expandable materials have hitherto been used primarily in the field of fire protection in buildings. So is out of the DE 296 17 849 U1 a cable duct for laying electrical lines known whose segments consist of a heat-resistant intumescent foam, which foams in the event of fire to form a resistant carbon structure and fills the interior of the segments under close enclosure of the lines, resulting in the extinguishment of a fire within a cable channel and the Going out of a cable fire leads.

In the use of the heat-expandable material according to the invention, however, the electrical power supply of a monitored electrical or electronic component is interrupted when the component has heated excessively. The heat-expandable material takes over as a functional material both a sensory and an actoric function by recognizing the one hand, the critical component state based on an impermissible heating and on the other hand, the electrical energy supply of the device directly or indirectly interrupts.

According to a first advantageous embodiment, the component to be monitored may be a surge-limiting component arranged in a housing of an overvoltage protection element, in particular a varistor or a gas-filled surge arrester, wherein the overvoltage protection element comprises two connection elements for electrical connection to a current or signal path to be protected having.

According to a preferred embodiment of the use of a heat-expandable material as a functional material for detecting an impermissible heating of an overvoltage limiting component, the overvoltage limiting component is in the normal state of the overvoltage protection element in a first position, in which in each case one pole of the overvoltage limiting component is in electrically conductive contact with a connection element, while the overvoltage limiting device is placed in thermal overload by the heat expansive expandable material in a second position in which the two poles of the overvoltage limiting device are no longer in electrical contact with the terminal elements. As a result of the expansion of the heat-expandable material, the overvoltage-limiting component is thus moved away from the connection elements, whereby the electrical connection of the overvoltage-limiting component is interrupted. In this case, the heat-expandable material consists of an insulating material, so that a possibly occurring during separation of the electrical contact between the poles of the overvoltage limiting component and the connecting elements arc is extinguished by the foaming, heat-expandable material.

In order to transfer the overvoltage-limiting component from the first position to the second position under thermal overload, it is necessary for a corresponding force to act on the component, which moves the component away from the connection elements. This force is preferably applied, as stated above, by the heat-expandable material itself, which is disposed in the housing such that, in the event of undue heating of the over-voltage limiting device, it pushes the device away from the terminals as the heat-expandable material expands. In principle, however, it is also possible that the force for displacing the overvoltage limiting component is applied by a separate spring element which is arranged between the housing and the overvoltage limiting component.

According to an alternative embodiment of the use of a heat-expandable material as a functional material for detecting an inadmissible heating of a surge-limiting device, in the normal state of the overvoltage protection element is also one pole of the overvoltage limiting component in electrically conductive contact with a connection element, it is provided that at least one pole of overvoltage limiting component via a movable connecting element with a connection element is in electrically conductive contact. In the case of thermal overload, the end of the connecting element facing the one pole of the overvoltage limiting component is deflected in such a way that the pole is no longer in electrically conductive contact with the corresponding connecting element.

In this case, a conductive slide or a metal tongue can be used as a connecting element, the first end of which is connected to a connection element and the second end in the normal state of the overvoltage protection element via a solder joint to a pole of the overvoltage limiting component. If there is an inadmissible heating of the overvoltage-limiting component, this leads to a melting of the solder joint and the slider or at least one end of the metal tongue is pushed away or deflected by the pole, preferably by the expands due to the heating heat-expandable material, so that the pole is no longer in electrically conductive contact with the corresponding connection element.

Instead of a slider or a metal tongue and a resilient separating tongue can be used as a connecting element which is deflected in the soldered state from its rest position and springs back during melting of the solder joint, so that the free end of the separation tongue moves away from the pole, whereby the overvoltage limiting component also electrically is separated.

As previously stated, it is preferable to apply the force for displacing the overvoltage limiting component or the force for pushing away the slider or for deflecting the end of the metal tongue from the heat-expandable material itself. In principle, however, this force can also be applied by a separate spring element or by the spring force of the resilient separating tongue. In this case, the heat-expandable material can also be used only to bring when moving the surge-limiting component or when deflecting the connecting element in the resulting gap between at least one pole of the surge-limiting component and at least one connection element or the end of the connecting element, so that a when the electrical contact between a pole and a terminal is broken, the arc resulting from the expansion of the heat-expandable material is extinguished.

Alternatively, the heat-expandable material may also be used to displace or displace an arc-extinguishing barrier slidably disposed in the housing of the overvoltage protection element by the expansion of the heat-expandable material between at least one pole of the overvoltage-limiting device and at least one connection element or the end of the connection element pivot, so that an emerging when disconnecting the electrical contact arc is interrupted by the barrier and thus deleted. This variant of the use of a heat-expandable material can be realized regardless of whether the overvoltage-limiting component or the movable connecting element is moved in the event of an overload by the heat-expandable material itself or by a spring away from the connecting elements or from the pole of the surge-limiting component.

According to a further advantageous embodiment, the heat-expandable material may additionally be used to cause a change in an optical status indication upon thermal overload by the expansion of the heat-expandable material and / or to actuate a remote-communicable status indication telecommunications contact. Also in these embodiments, the heat-expandable material as the functional material exerts both a sensory function and an actuator function.

In particular, there are now a variety of ways to design and develop the overvoltage protection element or electrical device according to the invention. Reference is made to both the claims subordinate to the independent claims and to the following description of preferred embodiments in conjunction with the drawings. In the drawing show

1 a sectional view of a first embodiment of an overvoltage protection element, in the normal state,

2 a sectional view of the overvoltage protection element according to 1 , with a separate varistor,

3 a further sectional view of an overvoltage protection element according to 1 , with a separate varistor,

4 a sectional view of a second embodiment of an overvoltage protection element, in the normal state,

5 a plan view of the overvoltage protection element according to 4 , in the normal state,

6 a sectional view of the overvoltage protection element according to 4 , with a separate surge arrester,

7 a sectional view of a third embodiment of an overvoltage protection element, in the normal state,

8th the overvoltage protection element according to 7 , in plan view,

9 the overvoltage protection element according to 8th , with a separate surge arrester, in plan view,

10 an example of an active heating according to an embodiment of an overvoltage protection element,

11 A second example of an active heating according to an embodiment of an overvoltage protection element,

12 A third example of an active heating according to an embodiment of an overvoltage protection element,

13 A fourth example of an active heating according to an embodiment of an overvoltage protection element,

14 a first embodiment of an electrical device, with a connecting member in a first position and in a second position,

15 a second embodiment of an electrical device, with a connecting member in a first position and in a second position, and

16 a third embodiment of an electrical device, with a connecting member in a first position and in a second position, and

17 an example of an active heating according to an embodiment of an electrical device, and

18 A second example of active heating according to an embodiment of an electrical device, and

19 a third example of an active heating according to an embodiment of an electrical device, and

20 A fourth example of an active heating according to an embodiment of an electrical device.

The figures show an overvoltage protection element 1 with a housing 2 , wherein in the housing 2 a surge limiting device is arranged. In the embodiment according to the 1 to 3 the overvoltage limiting component is a varistor 3 while it is the over-voltage protection element 1 according to the 4 to 9 around a gas-filled surge arrester 3 ' is.

The overvoltage protection element 1 according to the 1 to 3 , which may be formed as a protective plug, has two connection elements 4 . 5 on, which can be inserted into corresponding connection sockets of a device lower part, not shown here. The connection elements 4 . 5 are in the normal state of the overvoltage protection element 1 each with a pole of the varistor 3 connected so that the varistor 3 over the two connection elements 4 . 5 can be connected to the protected power or signal path.

Like from the 1 . 4 and 7 is apparent, is in the normal state of the overvoltage protection element 1 a heat-expandable material 6 in the case 2 arranged, which is first fixed, but changes its state of aggregation and becomes liquid with increasing temperature. When an activation temperature is exceeded, the heat-expandable material reacts 6 with a strong volume increase, ie the material 6 foams up and expands. This then causes the position of the varistor 3 or the surge arrester 3 ' relative to the position of the connection elements 4 . 5 changed because the heat-expandable material 6 the varistor 3 or the surge arrester 3 ' pushes away from his first position. In the embodiments according to the 2 and 6 is the varistor 3 or the surge arrester 3 ' while up and in the embodiment according to 9 pushed away to the side.

The overvoltage protection element 1 according to the 1 to 3 on the one hand and the overvoltage protection elements 1 according to the 4 to 9 On the other hand, initially different from each other in that in the first embodiment as overvoltage limiting component, a varistor 3 is used, while in the other embodiments, a gas-filled surge arrester 3 ' is used. In addition, the surge protection elements differ 1 nor by the type of electrical contact between the varistor 3 and the connection elements 4 . 5 on the one hand and the surge arrester on the other 3 ' and the connection elements 4 . 5 on the other hand.

While in the two embodiments according to the 4 and 7 in the normal state of the overvoltage protection element 1 the two poles of the surge arrester 3 ' each with a solder joint 7 . 8th with the two connection elements 4 . 5 are connected, are the two poles of the varistor 3 via a plug connection 9 . 10 with the two connection elements 4 . 5 in electrically conductive contact. Here are the two poles of the varistor 3 over two connection lugs 11 . 12 with the connection elements 4 . 5 connected, wherein the connection elements 4 . 5 on the connecting lugs 11 . 12 facing sides in each case a socket 13 . 14 having. At the in 4 illustrated embodiment of the overvoltage protection element 1 are the two poles of the surge arrester 3 ' each with a pin 15 . 16 connected so that the solder joints 7 . 8th between the pins 15 . 16 and the connection elements 4 . 5 are formed.

In the embodiment of the overvoltage protection element according to the invention 1 according to the 1 to 3 shows the case 2 an outer casing 17 and one in the outer casing 17 displaceable inner housing 18 on. As can be seen from the figures, the underside of the inner housing 18 open, leaving the inner case 18 the varistor 3 and the heat-expandable material 6 encloses hood-shaped. It comes due to an overload or due to aging of the varistor 3 to a reduction in the impedance of the varistor 3 , an impermissible leakage current flows through the varistor 3 , causing a heating of the varistor 3 leads. Because the varistor 3 at least partially of the heat-expandable material 6 surrounded, leads a self-heating of the varistor 3 also to a heating of the heat-expandable material 6 , so that this greatly expands when a certain activation temperature is exceeded. This leads to an increase in pressure within that of the outer housing 17 and the inner housing 18 enclosed space, leaving the inner casing 18 by the expanding heat-expandable material 6 is pushed upward when the holding force of the inner housing 18 inside the outer casing 17 and the contact force between the terminal lugs 11 . 12 and the sockets 13 . 14 by the force of the expanding heat-expandable material 6 is exceeded.

So that with the inner housing 18 also the varistor 3 moved up, is the varistor 3 via a holding element 19 with the inner housing 18 connected, wherein the holding element 19 below the varistor 3 is arranged and in the representation according to the 1 to 3 perpendicular to the plane of the drawing, ie in the transverse direction of the varistor 3 extends. The inner case 18 is thus similar to a piston in the outer housing 17 guided, wherein a not shown in the figures stop ensures that the lifting movement of the inner housing 18 is limited to the top.

How out 1 can be seen, there is the inner housing 18 in the normal state of the overvoltage protection element 1 in a first position within the outer housing 17 in which the top 20 of the inner casing 18 essentially flush with the top 21 of the outer casing 17 completes, leaving the top 20 of the inner casing 18 not over the outer casing 17 protrudes. In contrast to this is the inner housing 18 at thermal overload of the overvoltage protection element 1 after the electrical separation of the varistor 3 in one - in 2 illustrated - second position in which the top 20 of the inner casing 18 over the top 21 of the outer casing 17 protrudes. The position of the inner housing 18 thus serves as an optical status indicator for indicating the state of the overvoltage protection element 1 ,

It has previously been stated that the heat-expandable material 6 in the normal state of the overvoltage protection element 1 is firm and at a temperature rise initially liquid. To escape the liquid heat-expandable material 6 to safely prevent is in the illustrated embodiment above the connection elements 4 . 5 , ie. With respect to the open bottom of the inner housing 18 , a sealing foil 22 in the outer housing 17 arranged. The connecting straps extend here 11 . 12 in the normal state of the overvoltage protection element 1 through in the sealing foil 22 provided slots, so that the connecting lugs 11 . 12 from the sockets 13 . 14 contacted and thus with the connection elements 4 . 5 be in electrically conductive contact.

3 shows the overvoltage protection element 1 according to 1 in which the inner casing 18 is in the second position so that the varistor 3 is separated. In contrast to the representation according to 2 is in the illustration according to 3 the varistor 3 or the inner housing 18 but not by an expansion of the heat-expandable material 6 has been pushed upwards, but due to an overpressure caused by a bursting of the varistor 3 caused by extreme congestion. An extreme overload can be a varistor 3 abruptly put into a low-impedance state, so that in this extreme case, a mains-driven current in the size of the short-circuit current through the varistor 3 can flow. A in this case through the varistor 3 flowing current can lead to destruction and thus bursting of the varistor 3 to lead. The resulting pressure is over in the under the varistor 3 arranged holding element 19 trained opening 23 in through the outer housing 17 , the inner casing 18 and the sealing foil 22 formed space 24 directed. The one in this room 24 resulting pressure then causes the inner casing 18 from its first position to its second position is pushed up, which also causes the varistor 3 from the connection elements 4 . 5 is moved away, leaving the connecting lugs 11 . 12 no longer with the sockets 13 . 14 are in electrically conductive contact. The overloaded varistor 3 is thus separated reliably and quickly.

Indian in 3 shown position of the inner housing 18 can that in the room 24 existing increased pressure by the in the outer case 17 trained openings 25 escape. The openings 25 are so in the outer housing 17 arranged that they pass through the inner casing 18 are closed, as long as the inner housing 18 not yet in its second position.

At the in 4 illustrated embodiment of the overvoltage protection element 1 is the housing 2 not from an outer housing and an inner housing, but from two in cross section U-shaped holding elements 26 . 27 the next to the inclusion of the heat-expandable material 6 also for holding and contacting the pins 15 . 16 the surge arrester 3 ' in the normal state of the overvoltage protection element 1 serve. In the in the 4 to 9 illustrated embodiments of the overvoltage protection element 1 serve the two mutually insulated, electrically conductive holding elements 26 . 27 thus simultaneously as connection elements 4 . 5 for the gas-filled surge arrester 3 ' , Out 4 is it can be seen that in the normal state of the overvoltage protection element 1 one solder joint each 7 . 8th between the two pins 15 . 16 and the holding elements 26 . 27 is trained.

Does it come with this transitional protection element 1 to a heating of the surge arrester 3 ' , this also leads to a heating of the below the surge arrester 3 ' arranged heat-expandable material 6 so that it expands upon reaching its activation temperature. The surge arrester 3 ' is then pushed up when the of the heat-expandable material 6 applied force greater than the holding force of the softening solder joints 7 . 8th is. In this in 6 shown second position of the surge arrester 3 ' are the two pins 15 . 16 no longer in electrically conductive contact with the holding elements 26 . 27 so that the surge arrester 3 ' over the holding elements 26 . 27 no longer connected to the signal path to be protected. The electrical connection of the holding elements 26 . 27 with the signal path to be protected takes place in the embodiments according to the 4 to 9 in that the retaining elements 26 . 27 with a circuit board 28 are connected.

Instead of the solder joint between the pins shown in the figures 15 . 16 and the holding elements 26 . 27 Basically, a connector according to the 1 to 3 be provided. In this case, the retaining elements would 26 . 27 on the pins 15 . 16 facing sides have corresponding sockets.

While in the embodiment according to the 4 to 6 the holding elements 26 . 27 so formed and the heat-expandable material 6 such between the holding elements 26 . 27 is arranged, that under thermal overload of the surge arrester 3 ' this is due to the expanding heat-expandable material 6 is pushed up, the surge arrester 3 ' in the embodiment according to the 7 to 9 by the expanding heat-expandable material 6 pushed horizontally to the side.

In principle, when opening an electrical contact, over which a current flows, an arc can occur, which is the case with an overvoltage protection element 1 can lead to the fact that even in the actually separated state of the overvoltage limiting device on the arc still an impermissible current flows. Such an arc is at the in 2 illustrated embodiment of the overvoltage protection element 1 thereby preventing the expanding thermally expandable material 6 at thermal overload of the varistor 3 in the forming space between the terminal lugs 11 . 12 and the sockets 13 . 14 penetrates. Possible switching arcs are caused by the foaming of the connection lugs 11 . 12 deleted. This also applies to the in 9 illustrated left pin 15 the surge arrester 3 ' ,

In addition, also at the in 3 illustrated situation of the overvoltage protection element 1 one when disconnecting the electrical connection between the terminal lugs 11 . 12 and the sockets 13 . 14 extinguishing the pending arc are the two connection elements 4 . 5 from a plastic part 29 surrounded that is gassing at a pending arc. A pending arc is caused by the dissociation of plastic parts 29 thus generating a blowing of the arc, whereby the arc is extinguished.

In one embodiment, the particular activation temperature of the heat-expandable material is 6 above 80 ° C, especially above 120 ° C.

In another embodiment, the heat-expandable material 6 an increase in volume of at least twice the initial volume before activation.

In yet another embodiment, the heat-expandable material 6 a response time of less than 1 second for activation.

According to another embodiment of the invention, the heat-expandable material 6 a thermoplastic carrier.

The heat-expandable material 6 may comprise, for example, a thermoplastic polymer-based carrier selected from the group consisting of: acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylacetate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET) , Polyolefins, such as. Polyethylene (PE), polypropylene (PP), polyisobutylene (PIB), polybutylene (PB), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), polybutylene terephthalate (PBT) and celluloid, or the irreversible thermally expandable material 6 an elastomer having a Shore A hardness of less than 20 as a carrier.

According to yet another embodiment, the activation by external energy input, z. B. in case of error, causes.

This activation can be different. For example, the activation energy can be introduced by the heat-expanding material 6 itself is electrically conductive. For this purpose, the heat-expandable material 6 Shares of conductive materials such. As copper or graphite or an electrically conductive polymer. Such a material-supported energy input is in 10 shown.

Furthermore, the energy input by means of an energy-entry element 30 Alternatively or additionally be implemented by means of a heat pipe, as in 11 shown.

Furthermore, the energy input by means of an energy-entry element 30 alternatively or additionally be effected by means of a Widerstandheizelements, wherein the Widerstandheizelement is connected to the circuit. Such a measure is in 12 and 13 shown.

In 12 and 13 The energy input by means of a resistance wire as an energy-entry element 30 realized. Here, in the embodiment in FIG 12 , which also uses power through the switch for driving. In contrast, in 13 the current provided by another device in the activation case.

In yet another embodiment of the invention, the heat-expandable material 6 Microspheres on.

Furthermore, it is provided in a further embodiment that the heat-expandable material 6 a propellant and carrier, wherein the activation temperature of the propellant is less than the softening temperature of the carrier material.

Furthermore, in still another embodiment, it is contemplated that the heat-expandable material 6 a propellant and carrier, wherein the activation temperature of the propellant is higher than the softening temperature of the carrier material.

According to another embodiment, the heat-expandable material 6 an irreversibly expandable material.

According to yet another embodiment, the device is 1 a structural unit.

In yet another embodiment, it is contemplated that the heat-expandable material 6 has two components that are separated from each other in the non-activated state and in the activated state, the separation is canceled. For example, the heat-expandable material 6 Sodium bicarbonate and an acid, which are initially separated. If the separation is canceled, either by mechanical action or thermal action, the components react. The reaction releases gas, which leads to an increase in volume. Similar reactions are also with more-component polyurethanes or by means of fast-running oxidations, eg. B. at ignition of a combustion process to achieve.

The thermal expansion of the propellant is generally irreversible.

By suitable selection and arrangement of propellant material and carrier material, however, it can be achieved that the carrier material, upon cooling, returns the propellant to its initial state, ie. H. into the normal state, transferred.

This is achieved for example by the fact that z. B. microspheres embedded in a suitable plastic matrix.

These heat-expandable materials 6 are generally referred to as intumescent materials.

The in the 10 to 13 illustrated embodiments of the overvoltage protection element according to the invention 1 point on a top 31 of the housing 2 a viewing window 32 on.

The 14 and 15 show two different embodiments of a device 1 , in particular an electrical device 1 , with a housing 2 and with two associated conductor sections 33a . 33b which form the contacts of a switch. In contrast, the shows 16 an embodiment of an electrical device 1 with a housing 2 , which next to a first pair of mutually associated conductor sections 33a . 33b in addition, a second pair of mutually associated conductor sections 34a . 34b having. In the electrical devices shown in the figures 1 is inside the case 2 In addition, a connection component 3 '' slidably disposed so that it can be moved from a first position to a second position, wherein the 14a . 15a and 16a one electrical device each 1 with a connection component 3 '' in the first position and the 14b . 15b and 16b an electrical device 1 with a connection component 3 '' show in the second position. The first ends 36a . 36b the individual conductor sections 33a . 33b . 34a . 34b each protrude on one side 37 - In the illustrated embodiments of the bottom - from the housing 2 out, making them as connection elements for the electrical device 1 serve.

In the normal state ( 14a . 15a . 16a ) of the electrical device 1 is below the connection component 3 '' a heat-expandable material 6 in the case 2 arranged, which is first fixed in the normal operating state, but changes its state of aggregation and becomes liquid with increasing temperature. When an activation temperature is exceeded, the heat-expandable material reacts 6 with a strong volume increase, ie the material 6 foams up and expands. This then causes that to be slidable in the housing 2 arranged connection component 3 '' of the expanding thermally expandable material 6 from his first position ( 14a . 15a and 16a ) into its second position ( 14b . 15b and 16b ) is moved.

At the in 14 illustrated electrical device 1 contact the second ends 39a . 39b the conductor sections 33a . 33b the connection component 3 '' in the first position, leaving the two conductor sections 33a . 33b over the connecting component 3 '' electrically connected to each other. The contact points can be designed as pressure contacts, so that can be dispensed with solder joints. Will the activation temperature of the heat-expandable material 6 exceeded, then begins the non-reversible process of volume increase, resulting in that of the housing 2 and the connection component 3 '' enclosed space in which the heat-expandable material 6 is arranged, an overpressure builds up. Exceeds the force resulting from the overpressure on the connecting component 3 '' the contact force between the connecting member 3 '' and the second ends 39a . 39b the two conductor sections 33a . 33b , so open the contact points and the connecting member 3 '' is moved from its first position to its second position. The electrical device 1 according to 14 corresponds to its function thus designed as an opener switch.

Since the used heat-expandable material 6 Insulating is chosen, the electrical connection between the two conductor sections 33a . 33b initially interrupted by the fact that the expanding heat-expandable material 6 the connection component 3 '' pushes up, ie the contact points are opened, and then the heat-expandable material 6 the two conductor sections 33a . 33b isolated against each other. The occurrence of a switching arc when opening the contacts between the connecting component 3 '' and the second ends 39a . 39b the conductor sections 33a . 33b is characterized by the expanding, intumescent heat-expandable material 6 prevented.

Unlike the in 14 illustrated electrical device 1 are at the in 15 illustrated electrical device 1 the two conductor sections 33a . 33b in the first position of the connection component 3 '' electrically not connected to each other. An electrically conductive connection of the two conductor sections 33a . 33b over the connecting component 3 '' takes place in this embodiment only when the connecting member 3 '' by the expanding heat-expandable material 6 in his second - in 15b shown - position has been moved. In the second position becomes the connecting member 3 '' from the two second ends 39a . 39b the two conductor sections 33a . 33b contacted. The electrical device 1 according to 15 corresponds to its function thus designed as a closer switch. In this embodiment of the electrical device 1 it is not necessary that the heat-expandable material 6 is electrically insulating, since the conductor sections 33a . 33b such in a recess in the housing wall 40 are arranged that only the second ends 39a . 39b from the housing wall 40 out into the interior of the case 2 protrude.

16 shows a further embodiment of an electrical device 1 , wherein in this electrical device 1 - unlike the two electrical devices 1 according to the 14 and 15 - In addition to a first pair of mutually associated conductor sections 33a . 33b a second pair of associated conductor sections 34a . 34b is provided. The two conductor sections 33a . 34a are integrally connected. The electrical device 1 according to 16 corresponds to its function thus designed as a switch switch.

In the first position of the connection component 3 '' ( 16a ) are the two conductor sections 33a . 33b of the first pair via the connecting member 3 '' electrically connected together while the two conductor sections 34a . 34b of the second pair are not electrically connected to each other. In contrast, in the second position of the connecting member 3 '' ( 16b ) the two conductor sections 34a . 34b of the second pair via the connecting member 3 '' electrically connected together while the two conductor sections 33a . 33b of the first pair are not electrically connected to each other. In the first position of the connection component 3 '' is thus the through the two conductor sections 33a . 33b formed first switch closed and passing through the two conductor sections 34a . 34b formed second switch, while in the second position of the connecting member 3 '' the through the two conductor sections 33a . 33b formed first switch and opened by the two conductor sections 34a . 34b formed second switch is closed. Also in this embodiment, the heat-expandable material 6 made of an electrically insulating material.

The in the 14 to 16 illustrated embodiments of the electrical device according to the invention 1 point on a top 31 of the housing 2 a viewing window 32 on.

By the displacement of the connecting component 3 '' by the expanding heat-expandable material 6 not only a contact is opened or closed, but also the state of the electrical device 1 displayed. By a corresponding colored marking on the top of the connecting component 3 '' Thus, optical state detection is possible in a simple manner, since the connection component 3 '' in its second position immediately below the viewing window 32 in the top 31 of the housing 2 is arranged. Is the connection component 3 '' in its second position, this is by a user simply by looking at the viewing window 32 recognizable.

In addition or as an alternative to an optical status indication, the electrical device can 1 also be provided a fernübertragbare condition monitoring. This can be done inside the case 2 , preferably below the top 31 , a telecommunications contact to be arranged by the connecting member 3 '' is actuated when the connecting member 3 '' located in its second position.

In one embodiment, the particular activation temperature of the heat-expandable material is 6 above 80 ° C, especially above 120 ° C.

In another embodiment, the heat-expandable material 6 an increase in volume of at least twice the initial volume before activation.

In yet another embodiment, the heat-expandable material 6 a response time of less than 1 second for activation.

According to another embodiment of the invention, the heat-expandable material 6 a thermoplastic carrier.

The heat-expandable material 6 may comprise, for example, a thermoplastic polymer-based carrier selected from the group consisting of: acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylacetate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET) , Polyolefins, such as. Polyethylene (PE), polypropylene (PP), polyisobutylene (PIB), polybutylene (PB), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), polybutylene terephthalate (PBT) and celluloid, or the irreversible thermally expandable material 6 an elastomer having a Shore A hardness of less than 20 as a carrier.

According to yet another embodiment, the activation by external energy input, z. B. in case of error, causes.

This activation can be different. For example, the activation energy may be introduced by the heat-expandable material 6 itself is electrically conductive. For this purpose, the heat-expandable material 6 Shares of conductive materials such. As copper or graphite or an electrically conductive polymer. Such a material-supported energy input is in 17 shown.

Furthermore, the energy input by means of an energy-entry element 30 Alternatively or additionally be implemented by means of a heat pipe, as in 18 shown.

Furthermore, the energy input by means of an energy-entry element 30 alternatively or additionally be effected by means of a resistance heating element, wherein the resistance heating element is connected to the circuit. Such a measure is in 19 and 20 shown.

In 19 and 20 The energy input by means of a resistance wire as an energy-entry element 30 realized. Here, in the embodiment in FIG 19 , which also uses power through the switch for driving. In contrast, in 20 the current provided by another device in the activation case.

In yet another embodiment of the invention, the heat-expandable material 6 Microspheres on.

Furthermore, it is provided in a further embodiment that the heat-expandable material 6 a propellant and carrier, wherein the activation temperature of the propellant is less than the softening temperature of the carrier material.

Furthermore, in still another embodiment, it is contemplated that the heat-expandable material 6 a propellant and carrier, wherein the activation temperature of the propellant is higher than the softening temperature of the carrier material.

According to another embodiment, the heat-expandable material 6 an irreversibly heat-expandable material.

According to yet another embodiment, the device is 1 a structural unit.

In yet another embodiment, it is contemplated that the heat-expandable material 6 has two components that are separated from each other in the non-activated state and in the activated state, the separation is canceled. For example, the heat-expandable material 6 Sodium bicarbonate and an acid, which are initially separated. If the separation is abolished, either by mechanical action or thermal action, the components react. The reaction releases gas, which leads to an increase in volume. Similar reactions are also with more-component polyurethanes or by means of fast-running oxidations, eg. B. at ignition of a combustion process to achieve.

The thermal expansion of the propellant is generally irreversible.

By suitable selection and arrangement of propellant material and carrier material, however, it can be achieved that the carrier material, upon cooling, returns the propellant to its initial state, ie. H. into the normal state, transferred.

This is achieved for example by the fact that z. B. microspheres embedded in a suitable plastic matrix.

These heat-expandable materials are generally referred to as intumescent materials.

LIST OF REFERENCE NUMBERS

1

Overvoltage protection element, electrical device, device

2

casing

3

Overvoltage limiting component, varistor

3 '

Surge arrester, gas filled

3 ''

connecting member

4, 5

connection elements

6

heat-expandable material

7, 8

soldered point

9, 10

connector

11, 12

connection lugs

13, 14

socket

15, 16

pin

17

outer casing

18

inner housing

19

retaining element

20

Top of the inner housing

21

Top of the outer housing

22

sealing film

23

opening

24

room

25

opening

26, 27

retaining elements

28

circuit board

29

Plastic part

30

Energy input element

31

Top of the housing

32

window

33a, 33b

conductor section

34a, 34b

conductor section

36a, 36b

first ends of a conductor section

37

case side

39a, 39b

second ends of a conductor section

40

housing

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 4241311 A1 [0002]
• DE 202004006227 U1 [0003]
• DE 69904274 T2 [0004]
• DE 69503743 T2 [0005]
• DE 102005045778 A1 [0030, 0032]
• DE 29617849 U1 [0063]

Claims (30)

Device for overvoltage protection with a housing ( 2 ), with at least one in the housing ( 2 ) arranged overvoltage limiting component ( 3 ), in particular a varistor or a gas-filled surge arrester, and with two connection elements ( 4 . 5 ) for the electrical connection of the overvoltage protection element ( 1 ) to the protected current or signal path, wherein in the normal state of the overvoltage protection element ( 1 ) the connection elements ( 4 . 5 ) each with one pole of the overvoltage limiting component ( 3 ) are in electrically conductive contact, characterized in that inside the housing ( 2 ) a heat-expandable material ( 6 ) is arranged such that in case of thermal overload of the overvoltage limiting component ( 3 . 3 ' ) the position of the overvoltage limiting component ( 3 . 3 ' ) due to expansion of the heat-expandable material ( 6 ) relative to the position of the connecting elements ( 4 . 5 ) is variable such that at least one pole of the overvoltage limiting component ( 3 . 3 ' ) no longer with the corresponding connection element ( 4 . 5 ) is in electrically conductive contact. Apparatus according to claim 1, characterized in that in the normal state of the device ( 1 ) at least one pole of the overvoltage limiting component ( 3 . 3 ' ) via a solder joint ( 7 . 8th ) with at least one connecting element ( 4 . 5 ), wherein the at the solder joint ( 7 . 8th ) realized solder connection between a pole of the overvoltage limiting component ( 3 . 3 ' ) and a connecting element ( 4 . 5 ) when the temperature of the overvoltage limiting device ( 3 . 3 ' ) exceeds a predetermined activation temperature. Device with a housing ( 2 ), with at least two conductor sections ( 33a . 33b . 34a . 34b ) and with one inside the housing ( 2 ) arranged connecting member ( 3 '' ), characterized in that inside the housing ( 2 ) a heat-expandable material ( 6 ) is arranged such that the connecting component ( 3 '' ) by the heat-expandable material ( 6 ) can be brought from a first position to a second position when the heat-expandable material ( 6 ) due to an activation above a certain activation temperature, wherein either in the first position or in the second position of the connection component ( 3 '' ) the second ends ( 39a . 39b ) of two conductor sections ( 33a . 33b . 34a . 34b ) with the connecting component ( 3 '' ) are in electrical contact, so that the two conductor sections ( 33a . 33b . 34a . 34b ) via the connecting component ( 3 '' ) are electrically connected together. Device according to one of the preceding claims, characterized in that the determined activation temperature of the heat-expandable material ( 6 ) above 80 ° C, in particular above 120 ° C, is located. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) has a volume increase of at least twice the initial volume before activation. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) has a response time of less than 1 second for activation. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) comprises a thermoplastic carrier. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) comprises a thermoplastic polymer-based carrier selected from the group consisting of: acrylonitrile-butadiene-styrene (ABS), polyamides (PA), polylacetate (PLA), polymethyl methacrylate (PMMA), polycarbonate (PC), polyethylene terephthalate (PET), Polyolefins, such as. Polyethylene (PE), polypropylene (PP), polyisobutylene (PIB), polybutylene (PB), polystyrene (PS), polyetheretherketone (PEEK), polyvinyl chloride (PVC), polybutylene terephthalate (PBT) and celluloid, or the irreversible thermally expandable material ( 6 ) comprises an elastomer having a Shore A hardness of less than 20 as the carrier. Device according to one of the preceding claims, characterized in that the activation of the heat-expandable material ( 6 ) is effected by external energy input. Device according to one of the preceding claims, characterized in that the activation is effected by a resistance heating element, wherein the resistance heating element is connected to the circuit. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) Has microspheres. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) comprises a propellant and carrier, wherein the activation temperature of the propellant is less than the softening temperature of the carrier material. Device according to one of the preceding claims 1 to 11, characterized in that the heat-expandable material ( 6 ) comprises a propellant and carrier, wherein the activation temperature of the propellant is higher than the softening temperature of the carrier material. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) has an irreversibly expandable material. Device according to one of the preceding claims, characterized in that the device ( 1 ) is a structural unit. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) has two components which are separated from each other in the non-activated state and in the activated state, the separation is canceled. Apparatus according to claim 16, characterized in that the cancellation of the separation is brought about mechanically or thermally. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) is electrically conductive. Device according to one of the preceding claims, characterized in that the heat-expandable material ( 6 ) is an intumescent material. Use of heat-expandable material ( 6 ) in an electrical device ( 1 ), the device being a connection component ( 3 '' ) and at least two conductor sections ( 33a . 33b . 34a . 34b ), wherein the heat-expandable material ( 6 ) is arranged such that the connecting component ( 3 '' ) by the heat-expandable material ( 6 ) can be brought from a first position to a second position when the heat-expandable material ( 6 ) due to an activation above a certain activation temperature, wherein either in the first position or in the second position of the connection component ( 3 '' ) the second ends ( 39a . 39b ) of two conductor sections ( 33a . 33b . 34a . 34b ) with the connecting component ( 3 '' ) are in electrical contact, so that the two conductor sections ( 33a . 33b . 34a . 34b ) via the connecting component ( 3 '' ) are electrically connected together. Use of heat-expandable material ( 6 ) in an electrical device ( 1 ) for causing a separation of electrical conductors in the electrical device. Use of a heat-expandable material ( 6 ) as a functional material for detecting an impermissible heating of an electrical or electronic component ( 3 . 3 ' ) due to overloading or aging of the device ( 3 . 3 ' ), wherein the heat-expandable material expands when heated above a certain activation temperature and the expansion of the heat-expandable material, the electrical energy supply of the device is interrupted. Use of a heat-expandable material ( 6 ) as a functional material according to claim 21 or 22, characterized in that it is in the device to a arranged in a housing of an overvoltage protection element overvoltage limiting component, in particular a varistor ( 3 ) or a gas-filled surge arrester ( 3 ' ), wherein the overvoltage protection element has two connection elements for electrical connection of the overvoltage protection element to the current or signal path to be protected. Use of a heat-expandable material ( 6 ) as a functional material according to claim 21, 22 or 23, characterized in that the overvoltage limiting component ( 3 . 3 ' ) is in a first position in the normal state of the overvoltage protection element, in each of which one pole of the overvoltage limiting component is in electrically conductive contact with a connection element, and in that the overvoltage limiting component is thermally overloaded by the heat-expansible heat-expandable material ( 6 ) is moved to a second position, in which the two poles of the overvoltage limiting component are no longer in electrically conductive contact with the connection elements. Use of a heat-expandable material ( 6 ) as a functional material according to any one of the preceding claims 21 to 24, characterized in that in the normal state of the overvoltage protection element in each case one pole of the overvoltage limiting component is in electrically conductive contact with a connection element, that at least one pole of the overvoltage limiting component via a movable connecting element with a connection element is in electrically conductive contact, and that at least one of the pole of the overvoltage limiting device facing the end of the connecting element is deflected by thermal overload, preferably by the expands due to the heating heat-expandable material, so that at least one pole of the overvoltage limiting component no longer is in electrically conductive contact with the corresponding connection element. Use of a heat-expandable material ( 6 ) as a functional material according to one of the preceding claims 21 to 24, characterized in that the heat-expandable material penetrates upon thermal overload of the overvoltage limiting component between at least one pole of the overvoltage limiting component and at least one connection element or the end of the connecting element, so that if the separation of electrical contact between at least one pole and a connection element or the end of the connecting element an arc is formed, this by the insulating intumescent material ( 6 ) is suppressed or deleted. Use of a heat-expandable material ( 6 ) as a functional material according to any one of the preceding claims 21 to 26, with a displaceably arranged in the housing of the overvoltage protection element arc-extinguishing barrier, characterized in that the barrier in thermal overload by the heat-expands due to the heat-expandable material between at least one pole of the overvoltage limiting component and at least a connecting element or the end of the connecting element is displaced or pivoted, so that if an electric arc occurs during separation of the electrical contact between at least one pole and a connecting element or the end of the connecting element, it is deleted by the barrier. Use of an intumescent material ( 6 ) as a functional material according to one of the preceding claims 21 to 27, characterized in that a thermal state overload is caused by the expansion of the heat-expandable material, a change in an optical state display. Use of a heat-expandable material ( 6 ) as a functional material according to any one of the preceding claims 21 to 28, characterized in that when thermal overload by the expansion of the heat-expandable material, a telecommunications contact of a remotely transferable status display is actuated. Use of a heat-expandable material as a functional material according to any one of the preceding claims 21 to 29, characterized in that the heat-expandable material comprises an intumescent material.

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