EP0678891A1 - Current dependent switch - Google Patents

Current dependent switch Download PDF

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Publication number
EP0678891A1
EP0678891A1 EP95105956A EP95105956A EP0678891A1 EP 0678891 A1 EP0678891 A1 EP 0678891A1 EP 95105956 A EP95105956 A EP 95105956A EP 95105956 A EP95105956 A EP 95105956A EP 0678891 A1 EP0678891 A1 EP 0678891A1
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EP
European Patent Office
Prior art keywords
snap
disc
switch
resistance
bimetallic
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Granted
Application number
EP95105956A
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German (de)
French (fr)
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EP0678891B1 (en
Inventor
Marcel Hofsaess
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Thermik Geraetebau GmbH
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Thermik Geraetebau GmbH
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Publication of EP0678891A1 publication Critical patent/EP0678891A1/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H71/00—Details of the protective switches or relays covered by groups H01H73/00 - H01H83/00
    • H01H71/10—Operating or release mechanisms
    • H01H71/12—Automatic release mechanisms with or without manual release
    • H01H71/14—Electrothermal mechanisms
    • H01H71/16—Electrothermal mechanisms with bimetal element
    • H01H71/164—Heating elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01H—ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES
    • H01H37/00—Thermally-actuated switches
    • H01H37/02—Details
    • H01H37/32—Thermally-sensitive members
    • H01H37/52—Thermally-sensitive members actuated due to deflection of bimetallic element
    • H01H37/54—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting
    • H01H37/5427—Thermally-sensitive members actuated due to deflection of bimetallic element wherein the bimetallic element is inherently snap acting encapsulated in sealed miniaturised housing

Definitions

  • the present invention relates to a bimetallic switch, in particular a current-dependent switch, with a bimetallic disc and a snap disc which can be switched by the bimetallic disc and which causes current flow in a closed position of the switch and interrupts the current flow in an open position, the bimetallic disc and snap disc both being arranged in one housing and with a resistance element arranged in the circuit and formed on the snap disk, which heats up when a given current flow is exceeded such that the bimetallic disc switches from a low temperature to a high temperature position.
  • Such a bimetal switch is known from DE-OS 41 42 716.
  • the resistance element is an unadjusted element that is not accessible for mechanical adjustment.
  • the resistance element e.g. can be influenced by laser radiation with regard to its resistance.
  • This document deals in detail with resistance elements that are independent of the snap disk, it also discloses a snap disk itself designed as a resistance element.
  • This snap disc should be designed as a four-leg spring, as a round punch or as an etched part that has elastic capabilities after corresponding material deformation and e.g. has concentric semicircular webs with connecting material bridges between the individual semicircular webs. By means of several semicircular webs, an exact adjustment of the snap disk as a resistance element should be possible.
  • the snap disk is a current-carrying part in the closed state of the switch and therefore has a low electrical resistance. It consists of a material with high specific conductivity, such as copper beryllium in particular, and is preferably silver-plated.
  • This switch known from DE-OS 21 21 802 is used in this form as a temperature switch.
  • a resistance heating element is attached to the outside of the housing, e.g. in the form of a hybrid resistor. It is disadvantageous that this heating element requires a considerable heating power of up to 14 watts in order to open the switch in a sufficiently short time of at most 20, but preferably less than 14 seconds in the event of an excessive current flow, the high current flow, for example. due to a short circuit of a motor to be protected by the switch.
  • this object is achieved with a switch of the type mentioned at the outset in that the snap disc is made of material with low electrical conductivity, e.g. consists of steel or measurement, and that an increase in the resistance of the snap disk is brought about by material tapering, preferably by slots in the region of the edges of the snap disk.
  • the snap disc is made of material with low electrical conductivity, e.g. consists of steel or measurement, and that an increase in the resistance of the snap disk is brought about by material tapering, preferably by slots in the region of the edges of the snap disk.
  • the object underlying the invention is completely achieved in this way.
  • This mechanical, one-piece solution so to speak, allows the adjustment of the resistance of the snap disk in a surprisingly simple manner, without the mechanical properties thereof being changed appreciably.
  • the material tapers which are preferably provided as slots, can e.g. create by simple punching work that can be carried out quickly and inexpensively.
  • the snap disk is preferably made exclusively from material of low electrical conductivity, such as of steel, in particular of CrNiAl steel, or of brass. Another advantage of this design is that an air path is formed between the top and bottom of the discs, so that air can pass through the openings or slots provided in the switching case.
  • the snap properties of the snap disk are influenced only insignificantly or not at all by these openings or slots.
  • the present object is achieved according to the invention in a bimetal switch of the type mentioned at the outset in that the snap disk comprises a snap part on which a resistance layer with a defined resistance is applied as a resistance element.
  • the resistance layer can consist of a highly conductive material, but can be designed in such a way that the desired, defined, relatively high resistance for the current path is given.
  • the resistance layer will preferably not be formed over the entire surface of the snap part, but rather have a structure, for example in the form of conductor ribs, meander guides or the like.
  • the snap properties and the resistance properties are structurally separated from one another and assigned to different elements which are connected to one another. As a result, both properties can be set reproducibly with high accuracy, which applies in particular to the resistance of the resistance layer.
  • the arrangement of the resistance element on the snap disk ensures in both cases mentioned above that the heat generated in the case of an excessively high current does not first have to penetrate through the housing material from the outside into the interior of the switch to the bimetal disk in order to make it switch.
  • the switch consequently switches at a significantly lower heating power and can also switch faster and more reliably, since the heat source (resistance element) generated in the event of an overcurrent is arranged closer to the heat-sensitive bimetal element.
  • the resistance element has a contact resistance> 50 mOhm, in a further embodiment the contact resistance should be more than 100, in particular in the range of 200 mOhm.
  • the snap part has a very high specific resistance.
  • the advantage here is that the resistance layer can be applied directly to the snap part, since the electrical parallel connection of the snap part and the resistance layer only leads to an insignificant change in the resistance of the resistance layer. This measure is therefore particularly advantageous in terms of the structural simplicity.
  • the snap part is provided with the resistance layer by interposing an insulating layer, the insulating layer isolating the snap part against current flow.
  • the resistance layer is applied to the snap part by anodic arc evaporation.
  • the recently known anodic arc evaporation enables even flexible materials to be coated.
  • an arc discharge is generated between a cathode and an anode consisting of the coating material, the coating material evaporating in the arc and then being deposited on the surface to be coated.
  • the anodic vacuum arc can be used to generate a gas-free and droplet-free plasma, so that a highly pure, uniform layer is deposited.
  • the anodic arc can be used to deposit all possible materials, not only metals from aluminum to tin, but also alloys and high-melting elements such as tungsten or carbon.
  • ceramic layers can be produced by reactive evaporation, for which purpose aluminum, silicon or titanium are deliberately evaporated in an oxygen or nitrogen atmosphere.
  • corresponding resistance elements can be deposited or deposited on a conventional snap disk, which has the mechanical snap properties produced in a conventional manner, the total resistance of which is determined by the geometric shape and the thickness of the layer.
  • the resistance layer generated by anodic arc evaporation binds so firmly to the surface of the snap disk that even with a large number of switching cycles of the snap disk, the firm connection between the resistance layer and snap disk and the resistance value of the resistance layer itself are retained. In other words, even after many switching operations of the new bimetal switch, the resistance layer does not come off Snap disc off. The resistance layer also does not get any cracks or similar mechanical damage, as is known in other coating methods, if the carrier material or substrate is flexible and changes its shape frequently.
  • the switch can in principle be designed in any configuration, for example in one in which the bimetal and snap disk are clamped on one side and the snap disk carries a contact button at its opposite end
  • a preferred embodiment provides that the switch is axially symmetrical and Bimetal disc and snap disc are circular.
  • the snap disk rests with its outer peripheral edge in a low-temperature position in a bottom region of a conductive housing and presses with its inner peripheral edge against the collar of a movable contact button and, via this, the contact button against a stationary mating contact, which is insulated against the lower part of the housing arranged, also conductive cover is formed.
  • the bimetallic disc also surrounds the movable contact button in a ring shape, on the side of the collar of the contact button opposite the snap disk.
  • the switch is designed as a self-holding switch with a resistor of lower electrical conductivity, which is connected in parallel with the switching mechanism formed from the bimetal and snap disk. This included the use of the resistance element provided on the snap disk according to the invention in such a self-holding switch.
  • the bimetal switch 1 has a cup-shaped housing 2 made of electrically conductive material.
  • a snap disk 3 rests with its outer peripheral edge on the inside of the housing peripheral edge and presses with its edge surrounding a central opening against the collar of a contact button 4.
  • the housing 2 is closed by a likewise electrically conductive cover 7, which is electrically insulated from the housing pot 2 by an insulating film 8, such as preferably made of Kapton.
  • an insulating washer 9 such as made of Nomex.
  • a stationary contact 11 is located in the center of the inside of the cover 7. In the closed position of the switch 1 shown, the snap disk 3 presses the contact 4 against the stationary counter contact 11 via the collar 4a. This creates an electrically conductive connection between the housing 2 and the cover 7 via snap disk 3, contact 4 and mating contact 11.
  • the snap disk 3 consists of a material with a relatively high specific resistance or low specific electrical conductivity. While, for example, in conventional temperature switches that respond to external temperatures, the snap disk consists of silver-plated copper beryllium, the snap disk 3 can be made of steel or brass, optionally silver-plated, for the current switch according to the invention, which has a significantly higher specific resistance than copper, namely one in particular can have four to eight times as high specific resistance.
  • a snap disk made of spring steel can be chosen thinner than the known snap disk made of copper beryllium.
  • the bimetallic disc 6 In normal operation, in which an intended, not too high current flows, the bimetallic disc 6 is in the low-temperature position shown. In this position, the spring snap disk 3 presses the contact button 4 against the mating contact 11, so that, as said, the current flow from the lower housing part to the cover is ensured. If a fault occurs in the part to be protected against overcurrent, such as a motor or more precisely its coil winding, for example a short-circuit connection, the current flow through the switch 1 and in particular through the snap disk 3 increases; this heats up due to its relative high resistance, which causes a temperature in the housing that is above the switching temperature of the bimetallic disc 6.
  • overcurrent such as a motor or more precisely its coil winding, for example a short-circuit connection
  • the snap disc 3 is formed in multiple layers.
  • it has a snap part 13 made of a material with a very high specific resistance, on which a precisely defined resistance coating 14 is applied, which can optionally be guided around the outer edge of the snap part 13 for contacting in the outer edge area, as shown at 16.
  • the coating 14 does not have to completely cover the snap part 13, but can, for example, be designed with an inner peripheral edge toward the outside, the edge region 16 again being guided around the entire circumference.
  • the resistance between the outer edge 16 and the inner edge of the snap disk 3, which lies against the collar 4a of the contact 4 (FIG. 1) can be set extremely precisely.
  • a snap part 17 per se from a material with good conductivity or low specific resistance. In this case, it must be ensured that the snap part 17 itself does not establish a continuous electrical connection between the housing 2 and the contact 4 (FIG. 1).
  • an insulating coating 18 can first be applied to the snap part 17 of the snap disk 3, which covers the inside of the snap part 17 at 19 so that no electrical connection between the snap part 17 and the contact 4 is possible here; on the insulating layer 18 there is again a resistance layer 21, which can be guided around the snap part 17 at the outer edge (at 22) in the manner described with reference to FIG. 3, in order to ensure good contact with the bottom of the To effect housing 2.
  • the resistance layers 14, 21 are deposited, for example, by anodic arc evaporation on the snap part 13 or the insulating coating 18.
  • This new coating method leads to a very good mechanical connection between the resistance layer 14, 21 and the snap part 13 or the insulating coating 18, which does not suffer mechanically or electrically even with a large number of switching cycles of the snap disk 3.
  • an existing snap disk 3 of a known bimetal switch which previously had no current dependency, can be provided with a resistance layer by the anodic arc evaporation, so that the bimetal switch now also switches in a current-dependent manner. There are no structural changes to the snap disk 3, so that the mechanical snap properties are retained.

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  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Thermally Actuated Switches (AREA)
  • Electronic Switches (AREA)
  • Oscillators With Electromechanical Resonators (AREA)
  • Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
  • Push-Button Switches (AREA)

Abstract

A bimetallic switching element designed to open contacts at a specific level of current has a circular housing with a movable contact on a bimetallic disc (6) and a fixed contact (11) on the cap (7). Mounted directly below the bimetallic disc is a snap action disc (3) that is produced from a relatively low conductivity metal such as steel or brass. The resistance value of the disc is set by forming slots in the disc. At a specific value of current the disc responds to snap over and so opens the contacts. <IMAGE>

Description

Die vorliegende Erfindung betrifft einen Bimetallschalter, insbesondere einen stromabhängigen Schalter, mit einer Bimetallscheibe und einer von der Bimetallscheibe schaltbaren Schnappscheibe, die in einer Schließstellung des Schalters einen Stromfluß bewirkt und in einer Öffnungsstellung den Stromfluß unterbricht, wobei Bimetall- und Schnappscheibe beide in einem Gehäuse angeordnet sind, sowie mit einem im Stromkreis angeordneten und an der Schnappscheibe ausgebildeten Widerstandselement, das sich bei Überschreiten eines vorgebenen Stromflusses derart aufheizt, daß die Bimetallscheibe von einer Niedertemperatur- in eine Hochtemperaturstellung umschaltet.The present invention relates to a bimetallic switch, in particular a current-dependent switch, with a bimetallic disc and a snap disc which can be switched by the bimetallic disc and which causes current flow in a closed position of the switch and interrupts the current flow in an open position, the bimetallic disc and snap disc both being arranged in one housing and with a resistance element arranged in the circuit and formed on the snap disk, which heats up when a given current flow is exceeded such that the bimetallic disc switches from a low temperature to a high temperature position.

Ein derartiger Bimetallschalter ist aus der DE-OS 41 42 716 bekannt.Such a bimetal switch is known from DE-OS 41 42 716.

Bei dem bekannten Schalter ist das Widerstandselement ein unjustiertes Element, das einer mechanischen Justage nicht zugänglich ist. Es kann jedoch z.B. durch Laserbestrahlung hinsichtlich seines Widerstandes beeinflußt werden.In the known switch, the resistance element is an unadjusted element that is not accessible for mechanical adjustment. However, e.g. can be influenced by laser radiation with regard to its resistance.

Während sich diese Druckschrift ausführlich mit von der Schnappscheibe unabhängigen Widerstandselementen beschäftigt, offenbart sie auch eine selbst als Widerstandselement ausgebildete Schnappscheibe. Diese Schnappscheibe soll als Vier-Bein-Feder, als Rundstanz- oder als Ätzteil ausgebildet werden, das nach entsprechender Materialverformung elastische Fähigkeiten besitzt und z.B. über konzentrische Halbkreisstege mit Verbindungs-Materialbrücken zwischen den einzelnen Halbkreisstegen verfügt. Durch mehrere Halbkreisstege soll eine exakte Abstimmung der Schnappscheibe als Widerstandselement möglich sein.While this document deals in detail with resistance elements that are independent of the snap disk, it also discloses a snap disk itself designed as a resistance element. This snap disc should be designed as a four-leg spring, as a round punch or as an etched part that has elastic capabilities after corresponding material deformation and e.g. has concentric semicircular webs with connecting material bridges between the individual semicircular webs. By means of several semicircular webs, an exact adjustment of the snap disk as a resistance element should be possible.

Die genaue geometrische Form der hypothetisch erwähnten Schnappscheibe, das verwendete Material sowie die Art und Weise der Abstimmung des Widerstandswertes sind in dieser Druckschrift nicht beschrieben.The exact geometric shape of the hypothetically mentioned snap disk, the material used and the way in which the resistance value is coordinated are not described in this document.

Versuche bei der Anmelderin der vorliegenden Erfindung haben ergeben, daß bei gattungsgemäßen Bimetallschaltern besonderes Augenmerk darauf zu richten ist, daß einerseits die "Schnappeigenschaften" der Schnappscheibe richtig gewählt werden, um das gewünschte mechanische Schaltverhalten zu erzielen, und daß andererseits die "Widerstandseigenschaften" der mit dem Widerstandselement versehenen Schnappscheibe so bemessen sein müssen, daß der Bimetallschalter bei einem exakt einstellbaren Strom infolge der Eigenerwärmung des Widerstandselement öffnet.Experiments with the applicant of the present invention have shown that particular attention should be paid to generic bimetallic switches that, on the one hand, the "snap properties" of the snap disk are selected correctly in order to achieve the desired mechanical switching behavior, and that, on the other hand, the "resistance properties" of the snap disk provided with the resistance element must be dimensioned such that the bimetal switch opens at a precisely adjustable current due to the self-heating of the resistance element.

Die in der gattungsbildenden Druckschrift genannten Maßnahmen der Laser-Bestrahlung sowie der Halbkreisstege zur Einstellung eines definierten Widerstandes sind nicht nur zeitaufwendig und kostspielig, soweit sie denn überhaupt verstanden werden können, beeinträchtigen sie jedoch auf jeden Fall die Schnappeigenschaften, da sie komplizierte mechanische Veränderungen an der Schnappscheibe selbst mit sich bringen.The measures of laser irradiation and the semicircular webs for setting a defined resistance mentioned in the generic publication are not only time-consuming and expensive, as far as they can be understood at all, but they definitely impair the snap properties, since they involve complicated mechanical changes to the Bring the snap disk with you.

Weitere Schalter sind in Ausgestaltungen bekannt, bei denen die Schnappscheibe im Schließzustand des Schalters stromführendes Teil ist und daher einen geringen elektrischen Widerstand aufweist. Sie besteht aus einem Material hoher spezifischer Leitfähigkeit, wie insbesondere Kupferberyllium und ist vorzugsweise versilbert. Dieser aus der DE-OS 21 21 802 bekannte Schalter wird in dieser Form als Temperaturschalter eingesetzt. Zur Ausbildung des Schalters als stromabhängig schaltender Schalter wird an der Außenseite des Gehäuses ein Widerstands-Heizelement angebracht, z.B. in Form eines Hybridwiderstandes. Nachteilig ist, daß dieses Heizelement eine erhebliche Heizleistung von bis zu 14 Watt benötigt, um den Schalter in hinreichend kurzer Zeit von höchstens 20, vorzugsweise aber weniger als 14 Sekunden im Falle eines zu hohen Stromflusses zum Öffnen zu bringen, wobei der hohe Stromfluß bspw. aufgrund eines Kurzschlusses eines durch den Schalter zu schützenden Motors erfolgen kann.Further switches are known in configurations in which the snap disk is a current-carrying part in the closed state of the switch and therefore has a low electrical resistance. It consists of a material with high specific conductivity, such as copper beryllium in particular, and is preferably silver-plated. This switch known from DE-OS 21 21 802 is used in this form as a temperature switch. To form the switch as a current-dependent switch, a resistance heating element is attached to the outside of the housing, e.g. in the form of a hybrid resistor. It is disadvantageous that this heating element requires a considerable heating power of up to 14 watts in order to open the switch in a sufficiently short time of at most 20, but preferably less than 14 seconds in the event of an excessive current flow, the high current flow, for example. due to a short circuit of a motor to be protected by the switch.

Ausgehend hiervon ist es Aufgabe der vorliegenden Erfindung, den eingangs erwähnten Schalter dahingehend weiterzuentwickeln, daß auf konstruktiv einfache Weise sowohl die Schnappeigenschaften als auch die Widerstandseigenschaften eingestellt werden können, wobei diese Einstellung mit hoher Genauigkeit und reproduzierbar erfolgen soll.Proceeding from this, it is an object of the present invention to further develop the switch mentioned at the outset in such a way that that both the snap properties and the resistance properties can be set in a structurally simple manner, this setting should be carried out with high accuracy and reproducibly.

Erfindungsgemäß wird diese Aufgabe bei einem Schalter der eingangs genannten Art dadurch gelöst, daß die Schnappscheibe aus Material geringer elektrischer Leitfähigkeit, z.B. aus Stahl oder Messung besteht, und daß eine Erhöhung des Widerstandes der Schnappscheibe durch Materialverjüngung, vorzugsweise durch Schlitze im Bereich von Rändern der Schnappscheibe bewirkt ist.According to the invention, this object is achieved with a switch of the type mentioned at the outset in that the snap disc is made of material with low electrical conductivity, e.g. consists of steel or measurement, and that an increase in the resistance of the snap disk is brought about by material tapering, preferably by slots in the region of the edges of the snap disk.

Die der Erfindung zugrundeliegende Aufgabe wird auf diese Weise vollkommen gelöst. Diese sozusagen mechanische, einteilige Lösung läßt auf überraschend einfache Weise die Einstellung des Widerstandes der Schnappscheibe zu, ohne daß deren mechanische Eigenschaften merklich verändert werden. Die Materialverjüngungen, die vorzugsweise als Schlitze vorgesehen sind, lassen sich z.B. durch einfache Stanzarbeiten erzeugen, die schnell und kostengünstig durchzuführen sind. Die Schnappscheibe ist dabei vorzugsweise ausschließlich aus Material geringer elektrischer Leitfähigkeit hergestellt, wie z.B. aus Stahl, insbesondere aus CrNiAl-Stahl, oder aus Messing. Ein weiterer Vorteil dieser Ausbildung besteht darin, daß ein Luftweg zwischen Ober- und Unterseite der Scheiben gebildet ist, so daß im Schaltfall Luft durch die vorgesehenen Öffnungen oder Schlitze hindurchtreten kann. Andererseits werden durch diese Öffnungen oder Schlitze die Schnappeigenschaften der Schnappscheibe nur unwesentlich oder gar nicht beeinflußt.The object underlying the invention is completely achieved in this way. This mechanical, one-piece solution, so to speak, allows the adjustment of the resistance of the snap disk in a surprisingly simple manner, without the mechanical properties thereof being changed appreciably. The material tapers, which are preferably provided as slots, can e.g. create by simple punching work that can be carried out quickly and inexpensively. The snap disk is preferably made exclusively from material of low electrical conductivity, such as of steel, in particular of CrNiAl steel, or of brass. Another advantage of this design is that an air path is formed between the top and bottom of the discs, so that air can pass through the openings or slots provided in the switching case. On the other hand, the snap properties of the snap disk are influenced only insignificantly or not at all by these openings or slots.

Andererseits wird die vorliegende Aufgabe bei einem Bimetallschalter der eingangs genannten Art erfindungsgemäß dadurch gelöst, daß die Schnappscheibe ein Schnappteil umfaßt, auf das als Widerstandselement eine Widerstandsschicht mit definiertem Widerstand aufgebracht ist.On the other hand, the present object is achieved according to the invention in a bimetal switch of the type mentioned at the outset in that the snap disk comprises a snap part on which a resistance layer with a defined resistance is applied as a resistance element.

Auch auf diese Weise wird die vorliegende Aufgabe vollkommen gelöst. Die Widerstandsschicht kann aus gut leitfähigem Material bestehen, aber so ausgebildet sein, daß der gewünschte definierte, relativ hohe Widerstand für den Stromweg gegeben ist. Dabei wird die Widerstandsschicht vorzugsweise nicht vollflächig auf dem Schnappteil ausgebildet sein, sondern eine Struktur haben, bspw. in Form von Leiterrippen, Meanderführungen oder dergleichen. Auf jeden Fall werden die Schnappeigenschaften und die Widerstandseigenschaften konstruktiv voneinander getrennt und verschiedenen Elementen zugeordnet, die miteinander verbunden sind. Dadurch können beide Eigenschaften mit hoher Genauigkeit reproduzierbar eingestellt werden, was insbesondere für den Widerstand der Widerstandsschicht gilt.In this way too, the present task is completely solved. The resistance layer can consist of a highly conductive material, but can be designed in such a way that the desired, defined, relatively high resistance for the current path is given. The resistance layer will preferably not be formed over the entire surface of the snap part, but rather have a structure, for example in the form of conductor ribs, meander guides or the like. In any case, the snap properties and the resistance properties are structurally separated from one another and assigned to different elements which are connected to one another. As a result, both properties can be set reproducibly with high accuracy, which applies in particular to the resistance of the resistance layer.

Diese reproduzierbare Einstellung der Widerstandseigenschaften erlaubt auf konstruktiv einfache und preiswerte Weise eine genaue Einstellung sowohl des temperaturabhängigen als auch des stromabhängigen Schaltpunktes.This reproducible setting of the resistance properties allows a precise setting of both the temperature-dependent and the current-dependent switching point in a structurally simple and inexpensive manner.

Durch die Anordnung des Widerstandselementes an der Schnappscheibe wird in beiden oben erwähnten Fällen erreicht, daß die im Fall eines zu hohen Stromes erzeugte Wärme nicht erst durch das Gehäusematerial von außen ins Innere des Schalters zur Bimetallscheibe dringen muß, um diese zum Schalten zu bringen. Der Schalter schaltet folglich bei wesentlich geringerer Heizleistung und kann darüber hinaus schneller und zuverlässiger schalten, da die im Falle eines Überstromes erzeugte Wärmequelle (Widerstandselement) näher bei dem wärmeempfindlichen Bimetallelement angeordnet ist.The arrangement of the resistance element on the snap disk ensures in both cases mentioned above that the heat generated in the case of an excessively high current does not first have to penetrate through the housing material from the outside into the interior of the switch to the bimetal disk in order to make it switch. The switch consequently switches at a significantly lower heating power and can also switch faster and more reliably, since the heat source (resistance element) generated in the event of an overcurrent is arranged closer to the heat-sensitive bimetal element.

In bevorzugter Ausgestaltung ist vorgesehen, daß das Widerstandselement einen Übergangswiderstand > 50 mOhm hat, wobei in weiterer Ausbildung der Übergangswiderstand bei mehr als 100, insbesondere im Bereich von 200 mOhm liegen sollte.In a preferred embodiment it is provided that the resistance element has a contact resistance> 50 mOhm, in a further embodiment the contact resistance should be more than 100, in particular in the range of 200 mOhm.

Dabei ist es bevorzugt, daß das Schnappteil einen sehr hohen spezifischen Widerstand aufweist.It is preferred that the snap part has a very high specific resistance.

Hier ist von Vorteil, daß die Widerstandsschicht unmittelbar auf das Schnappteil aufgebracht werden kann, da die elektrische Parallelschaltung von Schnappteil und Widerstandsschicht nur zu einer unwesentlichen Veränderung des Widerstandes der Widerstandsschicht führt. Diese Maßnahme ist also insbesondere im Hinblick auf die konstruktive Einfachheit von Vorteil.The advantage here is that the resistance layer can be applied directly to the snap part, since the electrical parallel connection of the snap part and the resistance layer only leads to an insignificant change in the resistance of the resistance layer. This measure is therefore particularly advantageous in terms of the structural simplicity.

Weiter ist es bevorzugt, wenn das Schnappteil durch Zwischenlage einer Isolierschicht mit der Widerstandsschicht versehen ist, wobei die Isolierschicht das Schnappteil gegen Stromfluß isoliert.It is further preferred if the snap part is provided with the resistance layer by interposing an insulating layer, the insulating layer isolating the snap part against current flow.

Hier ist von Vorteil, daß auch Schnappteile mit anderen spezifischen Widerständen als den oben erwähnten hohen Widerständen verwendet werden können. Bei der Wahl der Materialien des Schnappteiles kann somit völlig auf die mechanischen Schnappeigenschaften abgestellt werden, ohne daß der begleitende Widerstand des Schnappteiles den Widerstand der Widerstandsschicht nachteilig beeinflußt.It is advantageous here that snap parts with specific resistances other than the high resistances mentioned above can also be used. When choosing the materials of the snap part, the mechanical snap properties can thus be completely adjusted without the accompanying resistance of the snap part adversely affecting the resistance of the resistance layer.

Dabei ist es allgemein bevorzugt, wenn die Widerstandsschicht durch anodische Lichtbogen-Verdampfung auf das Schnappteil aufgebracht ist.It is generally preferred if the resistance layer is applied to the snap part by anodic arc evaporation.

Die in letzter Zeit bekannt gewordene anodische Lichtbogen-Verdampfung ermöglicht es, sogar flexible Materialien zu beschichten. Bei diesem Verfahren wird eine Lichtbogenentladung zwischen einer Kathode und einer aus dem Beschichtungsmaterial bestehenden Anode erzeugt, wobei das Beschichtungsmaterial im Lichtbogen verdampft und sich dann auf der zu beschichtenden Fläche abscheidet. Im Gegensatz zu dem bekannten kathodischen Lichtbogen-Abscheideverfahren läßt sich mit dem anodischen Vakuum-Lichtbogen ein gas- und tröpfchenfreies Plasma erzeugen, so daß sich eine hochreine, gleichmäßige Schicht niederschlägt. Mit dem anodischen Lichtbogen lassen sich alle möglichen Materialien, nicht nur Metalle von Aluminium bis Zinn, sondern auch Legierungen und hochschmelzende Elemente wie Wolfram oder Kohlenstoff abscheiden. Darüber hinaus lassen sich durch reaktives Verdampfen auch keramische Schichten erzeugen, wozu Aluminium, Silicium oder Titan bewußt in einer Sauerstoff- oder Stickstoffatmosphäre verdampft werden.The recently known anodic arc evaporation enables even flexible materials to be coated. In this method, an arc discharge is generated between a cathode and an anode consisting of the coating material, the coating material evaporating in the arc and then being deposited on the surface to be coated. In contrast to the known cathodic arc deposition process, the anodic vacuum arc can be used to generate a gas-free and droplet-free plasma, so that a highly pure, uniform layer is deposited. The anodic arc can be used to deposit all possible materials, not only metals from aluminum to tin, but also alloys and high-melting elements such as tungsten or carbon. In addition, ceramic layers can be produced by reactive evaporation, for which purpose aluminum, silicon or titanium are deliberately evaporated in an oxygen or nitrogen atmosphere.

Mit diesem Verfahren können auf einer üblichen Schnappscheibe, die die auf herkömmliche Weise erzeugten mechanischen Schnappeigenschaften aufweist, entsprechende Widerstandselemente abgeschieden oder abgelagert werden, deren Gesamtwiderstand durch die geometrische Form sowie die Dicke der Schicht bestimmt ist.With this method, corresponding resistance elements can be deposited or deposited on a conventional snap disk, which has the mechanical snap properties produced in a conventional manner, the total resistance of which is determined by the geometric shape and the thickness of the layer.

Insbesondere von Vorteil ist hier, daß die durch anodische Lichtbogen-Verdampfung erzeugte Widerstandsschicht so fest an die Oberfläche der Schnappscheibe bindet, daß auch bei sehr vielen Schaltspielen der Schnappscheibe die feste Verbindung zwischen Widerstandsschicht und Schnappscheibe sowie der Widerstandswert der Widerstandsschicht selbst erhalten bleiben. Mit anderen Worten, auch nach vielen Schaltvorgängen des neuen Bimetallschalters springt die Widerstandsschicht nicht von der Schnappscheibe ab. Die Widerstandsschicht bekommt auch keine Risse oder ähnliche mechanische Beschädigungen, wie sie bei anderen Beschichtungsverfahren bekannt sind, wenn das Trägermaterial oder Substrat flexibel ist und seine Gestalt häufig ändert.It is particularly advantageous here that the resistance layer generated by anodic arc evaporation binds so firmly to the surface of the snap disk that even with a large number of switching cycles of the snap disk, the firm connection between the resistance layer and snap disk and the resistance value of the resistance layer itself are retained. In other words, even after many switching operations of the new bimetal switch, the resistance layer does not come off Snap disc off. The resistance layer also does not get any cracks or similar mechanical damage, as is known in other coating methods, if the carrier material or substrate is flexible and changes its shape frequently.

Während der Schalter grundsätzlich in jeder Ausgestaltung ausgebildet sein kann, bspw. in einer solchen, bei der Bimetall- und Schnappscheibe einseitig eingespannt sind und an ihrem gegenüberliegenden Ende die Schnappscheibe einen Kontaktknopf trägt, sieht eine bevorzugte Ausgestaltung vor, daß der Schalter achssymmetrisch ausgebildet ist und Bimetallscheibe sowie Schnappscheibe kreisringförmig ausgebildet sind. Hierbei liegt in der Regel die Schnappscheibe mit ihrem äußeren Umfangsrand in einer Niedertemperaturstellung in einem Bodenbereich eines leitfähigen Gehäuses auf und drückt mit ihrem inneren Umfangsrand gegen den Bund eines beweglichen Kontaktknopfes und über diesen den Kontaktknopf gegen einen stationären Gegenkontakt, der an einem isoliert gegenüber dem Gehäuseunterteil angeordneten, ebenfalls leitfähigen Deckel ausgebildet ist. Die Bimetallscheibe umgibt ebenfalls kreisringförmig den beweglichen Kontaktknopf, und zwar auf der der Schnappscheibe gegenüberliegenden Seite des Bundes des Kontaktknopfes.While the switch can in principle be designed in any configuration, for example in one in which the bimetal and snap disk are clamped on one side and the snap disk carries a contact button at its opposite end, a preferred embodiment provides that the switch is axially symmetrical and Bimetal disc and snap disc are circular. As a rule, the snap disk rests with its outer peripheral edge in a low-temperature position in a bottom region of a conductive housing and presses with its inner peripheral edge against the collar of a movable contact button and, via this, the contact button against a stationary mating contact, which is insulated against the lower part of the housing arranged, also conductive cover is formed. The bimetallic disc also surrounds the movable contact button in a ring shape, on the side of the collar of the contact button opposite the snap disk.

Eine äußerst bevorzugte Ausgestaltung sieht vor, daß der Schalter als selbsthaltender Schalter mit einem zu dem aus Bimetall- und Schnappscheibe gebildeten Schaltwerk parallel geschalteten Widerstand geringerer elektrischer Leitfähigkeit ausgebildet ist. Dies beinhaltete die Anwendung des erfindungsgemäß an der Schnappscheibe vorgesehenen Widerstandselementes bei einem derartigen selbsthaltenden Schalter.An extremely preferred embodiment provides that the switch is designed as a self-holding switch with a resistor of lower electrical conductivity, which is connected in parallel with the switching mechanism formed from the bimetal and snap disk. This included the use of the resistance element provided on the snap disk according to the invention in such a self-holding switch.

Weitere Vorteile und Merkmale der Erfindung ergeben sich aus den Ansprüchen und aus der nachfolgenden Beschreibung, in der Ausführungsbeispiele des erfindungsgemäßen Bimetallschalters unter Bezugnahme auf die Zeichnungen im einzelnen erläutert sind. Dabei zeigt:

Fig. 1
eine erste Ausführungsform des erfindungsgemäßen Schalters im Schnitt;
Fig. 2
eine Draufsicht auf eine spezielle Ausbildung einer erfindungsgemäßen Schnappscheibe;
Figuren 3 und 4
Schnitte durch andere Ausführungsformen einer erfindungsgemäß verwendeten Schnappscheibe.
Further advantages and features of the invention result from the claims and from the following description in which exemplary embodiments of the bimetal switch according to the invention are explained in detail with reference to the drawings. It shows:
Fig. 1
a first embodiment of the switch according to the invention in section;
Fig. 2
a plan view of a special embodiment of a snap disk according to the invention;
Figures 3 and 4
Cuts through other embodiments of a snap disk used according to the invention.

Der erfindungsgemäße Bimetallschalter 1 weist in der dargestellten Ausführungsform ein topfförmiges Gehäuse 2 aus elektrisch leitendem Material auf. Eine Schnappscheibe 3 liegt mit ihrem äußeren Umfangsrand auf der Innenseite des Gehäuseumfangsrandes auf und drückt mit ihrem eine mittlere Öffnung umgebenden Rand gegen den Bund eines Kontaktknopfes 4. Auf der der Schnappscheibe 3 abgewandten Seite des Bundes 4a des Kontaktknopfes 4 liegt eine Bimetallscheibe 6 auf, die in der Fig. 1 in ihrer spannungslosen Tieftemperaturstellung gezeigt ist. Das Gehäuse 2 ist durch einen ebenfalls elektrisch leitenden Deckel 7 verschlossen, der gegenüber dem Gehäusetopf 2 durch eine Isolierfolie 8, wie vorzugsweise aus Kapton, elektrisch isoliert ist. Auf dem Deckel 7 befindet sich eine Isolierscheibe 9, wie aus Nomex. Auf der Innenseite des Deckels 7 befindet sich mittig ein stationärer Kontakt 11. Die Schnappscheibe 3 drückt in der dargestellten Schließstellung des Schalters 1 über den Bund 4a den Kontakt 4 gegen den stationären Gegenkontakt 11. Hierdurch wird eine elektrisch leitende Verbindung zwischen dem Gehäuse 2 und dem Deckel 7 über Schnappscheibe 3, Kontakt 4 und Gegenkontakt 11 hergestellt.In the embodiment shown, the bimetal switch 1 according to the invention has a cup-shaped housing 2 made of electrically conductive material. A snap disk 3 rests with its outer peripheral edge on the inside of the housing peripheral edge and presses with its edge surrounding a central opening against the collar of a contact button 4. On the side of the snap disk 3 facing away from the collar 4a of the contact button 4 there is a bimetal disk 6 which is shown in Fig. 1 in its de-energized low temperature position. The housing 2 is closed by a likewise electrically conductive cover 7, which is electrically insulated from the housing pot 2 by an insulating film 8, such as preferably made of Kapton. On the lid 7 there is an insulating washer 9, such as made of Nomex. A stationary contact 11 is located in the center of the inside of the cover 7. In the closed position of the switch 1 shown, the snap disk 3 presses the contact 4 against the stationary counter contact 11 via the collar 4a. This creates an electrically conductive connection between the housing 2 and the cover 7 via snap disk 3, contact 4 and mating contact 11.

Damit der Schalter 1 als solcher in der dargestellten Ausführungsform als Stromschalter wirkt, besteht die Schnappscheibe 3 aus einem Material mit relativ hohem spezifischem Widerstand bzw. geringer spezifischer elektrischer Leitfähigkeit. Während beispielsweise bei herkömmlichen Temperaturschaltern, die auf externe Temperaturen ansprechen, die Schnappscheibe aus versilbertem Kupferberyllium besteht, kann für den dargestellten erfindungsgemäßen Stromschalter die Schnappscheibe 3 aus Stahl oder Messing, gegebenenfalls versilbert, bestehen, die gegenüber Kupfer einen wesentlich höheren spezifischen Widerstand, nämlich einen insbesondere vier- bis achtmal so hohen spezifischen Widerstand haben können. Falls der spezifische Widerstand bei gleichen Flächenmaßen der Schnappscheibe 3 noch höher sein soll, so können andere geeignete Legierungen mit hohem Widerstand eingesetzt werden; darüber hinaus kann bei gleichen mechanischen Schnapp- und Andruckeigenschaften eine Schnappscheibe aus Federstahl dünner gewählt werden als die bekannte Schnappscheibe aus Kupferberyllium.So that the switch 1 acts as such in the illustrated embodiment as a current switch, the snap disk 3 consists of a material with a relatively high specific resistance or low specific electrical conductivity. While, for example, in conventional temperature switches that respond to external temperatures, the snap disk consists of silver-plated copper beryllium, the snap disk 3 can be made of steel or brass, optionally silver-plated, for the current switch according to the invention, which has a significantly higher specific resistance than copper, namely one in particular can have four to eight times as high specific resistance. If the specific resistance is to be even higher with the same area dimensions of the snap disk 3, then other suitable alloys with high resistance can be used; In addition, with the same mechanical snap and pressure properties, a snap disk made of spring steel can be chosen thinner than the known snap disk made of copper beryllium.

Im normalen Betriebsfall, in dem ein vorgesehener, nicht allzu hoher Strom fließt, befindet sich die Bimetallscheibe 6 in ihrer dargestellten Niedertemperaturstellung. In dieser Stellung drückt die Federschnappscheibe 3 den Kontaktknopf 4 gegen den Gegenkontakt 11, so daß, wie gesagt, der Stromfluß vom Gehäuseunterteil zum Deckel sichergestellt ist. Wenn bei dem gegen Überstrom zu schützenden Teil, wie beispielsweise einem Motor oder genauer dessen Spulenwicklung, ein Fehler auftritt, beispielsweise eine Kurzschlußverbindung, so erhöht sich der Stromfluß durch den Schalter 1 und insbesondere durch die Schnappscheibe 3; diese erwärmt sich aufgrund ihres relativ hohen Widerstandes, wodurch im Gehäuse eine Temperatur bewirkt wird, die oberhalb der Schalttemperatur der Bimetallscheibe 6 liegt. Diese springt dann in ihre nicht dargestellte Hochtemperaturstellung, bei der sie mit ihrem äußeren Umfangsrand sich an der Unterseite des Deckels 7 (bzw. der dort befindlichen Isolierfolie 8) abstützt und mit ihrem inneren Umfangsrand den Bund 4a des Kontaktknopfes 4 und damit diesen nach unten drückt, wodurch die elektrische Verbindung zwischen Kontaktknopf 4 und Gegenkontakt 11 geöffnet und damit der Stromfluß unterbrochen wird. Nach Abkühlung springt die Bimetallscheibe 6 wieder in ihre dargestellte Stellung um, so daß der Schalter dann wieder schließt. Die erfindungsgemäße Ausgestaltung der Schnappscheibe mit relativ hohem Übergangswiderstand kann auch bei einem selbsthaltenden Schalter realisiert sein, wie er beispielsweise aus der DE-OS 37 10 672 bekannt ist.In normal operation, in which an intended, not too high current flows, the bimetallic disc 6 is in the low-temperature position shown. In this position, the spring snap disk 3 presses the contact button 4 against the mating contact 11, so that, as said, the current flow from the lower housing part to the cover is ensured. If a fault occurs in the part to be protected against overcurrent, such as a motor or more precisely its coil winding, for example a short-circuit connection, the current flow through the switch 1 and in particular through the snap disk 3 increases; this heats up due to its relative high resistance, which causes a temperature in the housing that is above the switching temperature of the bimetallic disc 6. This then jumps into its high-temperature position, not shown, in which it is supported with its outer peripheral edge on the underside of the cover 7 (or the insulating film 8 located there) and with its inner peripheral edge presses the collar 4a of the contact button 4 and thus downwards , whereby the electrical connection between the contact button 4 and counter contact 11 is opened and thus the current flow is interrupted. After cooling, the bimetallic disc 6 jumps back into the position shown, so that the switch closes again. The inventive design of the snap disk with a relatively high contact resistance can also be realized with a self-holding switch, as is known for example from DE-OS 37 10 672.

Alternativ oder zusätzlich zu den oben beschriebenen Maßnahmen zur Erhöhung des Durchgangs- oder Übergangswiderstandes der Schnappscheibe 3 sind weitere Ausbildungen möglich. So zeigt die Fig. 2 eine Schnappscheibe 3 mit am Innenumfang vorgesehenen radialen Schlitzen 12. Hierdurch wird der Widerstand zwischen dem Außenumfang der Scheibe 3 und den verbleibenden Innenrandbereichen und damit der Gesamtwiderstand der Scheibe 3 ebenfalls erhöht.As an alternative or in addition to the measures described above for increasing the volume or transition resistance of the snap disk 3, further designs are possible. 2 shows a snap disk 3 with radial slots 12 provided on the inner circumference. As a result, the resistance between the outer circumference of the disk 3 and the remaining inner edge regions and thus the total resistance of the disk 3 are also increased.

Durch die Schlitze 12 werden Ventilationsöffnungen zwischen dem Bereich oberhalb und unterhalb der Schnappscheibe 3 geschaffen, so daß hier in vorteilhafter Weise ein Temperaturausgleich stattfinden kann; darüber hinaus kann beim Umschalten der Schnappscheibe 3 aus der in Fig. 1 dargestellten (Niedertemperatur-)Stellung unterhalb der Schnappscheibe befindliche Luft zur Oberseite durchtreten, so daß einseitig nicht ein Luftpolster als gegenwirkende (Luft-)Feder wirken kann.Through the slots 12 ventilation openings between the area above and below the snap disc 3 are created, so that here temperature compensation can take place in an advantageous manner; in addition, when switching the snap disk 3 from the (low-temperature) position shown in FIG. 1, air below the snap disk can pass through to the upper side, so that an air cushion cannot act as a counteracting (air) spring on one side.

In weiterer Ausbildung kann vorgesehen sein, daß die Schnappscheibe 3 mehrschichtig ausgebildet ist. Sie weist nach der Ausführungsform der Fig. 3 ein Schnappteil 13 aus einem Material mit sehr hohem spezifischen Widerstand auf, auf dem eine genau definierte Widerstandsbeschichtung 14 aufgebracht ist, die zur Kontaktierung im äußeren Randbereich gegebenenfalls um die äußere Kante des Schnappteils 13 herumgeführt sein kann, wie dies bei 16 dargestellt ist. Die Beschichtung 14 muß das Schnappteil 13 nicht vollständig bedecken, sondern kann beispielsweise mit einem inneren umlaufenden Rand nach außen hin strahlenförmig ausgebildet sein, wobei der Randbereich 16 wiederum um den gesamten Umfang geführt ist. Hierdurch kann der Widerstand zwischen dem äußeren Rand 16 und dem inneren, am Bund 4a des Kontakts 4 (Fig. 1) anliegenden Rand der Schnappscheibe 3 äußerst genau eingestellt werden.In a further embodiment, it can be provided that the snap disc 3 is formed in multiple layers. According to the embodiment of FIG. 3, it has a snap part 13 made of a material with a very high specific resistance, on which a precisely defined resistance coating 14 is applied, which can optionally be guided around the outer edge of the snap part 13 for contacting in the outer edge area, as shown at 16. The coating 14 does not have to completely cover the snap part 13, but can, for example, be designed with an inner peripheral edge toward the outside, the edge region 16 again being guided around the entire circumference. As a result, the resistance between the outer edge 16 and the inner edge of the snap disk 3, which lies against the collar 4a of the contact 4 (FIG. 1), can be set extremely precisely.

Es ist auch möglich, ein Schnappteil 17 (Fig. 4) an sich aus einem Material mit guter Leitfähigkeit bzw. geringem spezifischen Widerstand auszubilden. In diesem Falle ist dafür zu sorgen, daß das Schnappteil 17 selbst keine durchgehende elektrische Verbindung zwischen dem Gehäuse 2 und dem Kontakt 4 (Fig. 1) herstellt. Hierzu kann zunächst auf dem Schnappteil 17 der Schnappscheibe 3 eine isolierende Beschichtung 18 aufgebracht sein, die die Innenseite des Schnappteils 17 bei 19 isolierend abdeckt, so daß hier keine elektrische Verbindung zwischen dem Schnappteil 17 und dem Kontakt 4 möglich ist; auf der Isolierschicht 18 befindet sich dann wieder eine Widerstandsschicht 21, die am äußeren Rand (bei 22) in der unter Bezugnahme auf die Fig. 3 beschriebenen Weise um das Schnappteil 17 herumgeführt sein kann, um in diesem Bereich eine gute Kontaktierung mit dem Boden des Gehäuses 2 zu bewirken.It is also possible to form a snap part 17 (FIG. 4) per se from a material with good conductivity or low specific resistance. In this case, it must be ensured that the snap part 17 itself does not establish a continuous electrical connection between the housing 2 and the contact 4 (FIG. 1). For this purpose, an insulating coating 18 can first be applied to the snap part 17 of the snap disk 3, which covers the inside of the snap part 17 at 19 so that no electrical connection between the snap part 17 and the contact 4 is possible here; on the insulating layer 18 there is again a resistance layer 21, which can be guided around the snap part 17 at the outer edge (at 22) in the manner described with reference to FIG. 3, in order to ensure good contact with the bottom of the To effect housing 2.

Die Widerstandsschichten 14, 21 werden bspw. durch anodische Lichtbogen-Verdampfung auf dem Schnappteil 13 oder der isolierenden Beschichtung 18 abgeschieden. Dieses neue Beschichtungsverfahren führt zu einer sehr guten mechanischen Verbindung zwischen der Widerstandsschicht 14, 21 und dem Schnappteil 13 bzw. der isolierenden Beschichtung 18, die auch bei einer großen Anzahl von Schaltspielen der Schnappscheibe 3 weder mechanisch noch elektrisch leidet. Im einfachsten Falle kann so eine bestehende Schnappscheibe 3 eines bekannten Bimetallschalters, der bisher keine Stromabhängigkeit aufwies, durch die anodische Lichtbogen-Verdampfung mit einer Widerstandsschicht versehen werden, so daß der Bimetallschalter jetzt auch stromabhängig schaltet. Konstruktiv sind an der Schnappscheibe 3 keine Änderungen vorzunehmen, so daß die mechanischen Schnappeigenschaften erhalten bleiben. Bei der Fertigung eines derartigen, bisher nicht stromabhängig schaltenden Bimetallschalters ist also lediglich ein weiterer Fertigungsschritt einzuschalten, bei dem die bekannte Schnappscheibe mit einer Widerstandsschicht versehen wird. Erstaunlicherweise wurde gefunden, daß dieses verglichen mit dem aus der DE-OS-41 42 716 bekannten Verfahren konstruktiv sehr einfache Verfahren ohne mechanische Änderungen an dem Aufbau des Bimetallschalters möglich ist.The resistance layers 14, 21 are deposited, for example, by anodic arc evaporation on the snap part 13 or the insulating coating 18. This new coating method leads to a very good mechanical connection between the resistance layer 14, 21 and the snap part 13 or the insulating coating 18, which does not suffer mechanically or electrically even with a large number of switching cycles of the snap disk 3. In the simplest case, an existing snap disk 3 of a known bimetal switch, which previously had no current dependency, can be provided with a resistance layer by the anodic arc evaporation, so that the bimetal switch now also switches in a current-dependent manner. There are no structural changes to the snap disk 3, so that the mechanical snap properties are retained. In the manufacture of such a bimetal switch, which has not yet switched in a current-dependent manner, it is therefore only necessary to switch on a further production step in which the known snap disk is provided with a resistance layer. Surprisingly, it was found that, compared to the method known from DE-OS-41 42 716, this method is structurally very simple without mechanical changes to the structure of the bimetal switch.

Insgesamt wird durch die genannten Maßnahmen ein äußerst zuverlässiger stromabhängiger Schalter geschaffen, der bei kleinen Heizleistungen ein schnelles und reproduzierbares Schaltverhalten zeigt.All in all, the measures mentioned create an extremely reliable current-dependent switch that shows fast and reproducible switching behavior at low heating outputs.

Claims (8)

Bimetallschalter, insbesondere stromabhängiger Schalter (1), mit einer Bimetallscheibe (6) und einer von der Bimetallscheibe (6) schaltbaren Schnappscheibe (3), die in einer Schließstellung des Schalters (1) einen Stromfluß bewirkt und in einer Öffnungsstellung den Stromfluß unterbricht, wobei Bimetall- und Schnappscheibe (6, 3) beide in einem Gehäuse (2) angeordnet sind, sowie mit einem im Stromkreis angeordneten und an der Schnappscheibe ausgebildeten Widerstandselement (3; 14, 21), das sich bei Überschreiten eines vorgegebenen Stromflusses derart aufheizt, daß die Bimetallscheibe (6) von einer Niedertemperatur- in eine Hochtemperaturstellung umschaltet, dadurch gekennzeichnet, daß die Schnappscheibe (3) aus Material geringer elektrischer Leitfähigkeit, z.B. aus Stahl oder Messing besteht, und daß eine Erhöhung des Widerstandes der Schnappscheibe (3) durch Materialverjüngung, vorzugsweise durch Schlitze (12) im Bereich von Rändern der Schnappscheibe (3) bewirkt ist.Bimetallic switch, in particular current-dependent switch (1), with a bimetallic disc (6) and a snap disc (3) which can be switched by the bimetallic disc (6), which causes a current flow in a closed position of the switch (1) and interrupts the current flow in an open position, whereby Bimetallic and snap disc (6, 3) are both arranged in a housing (2), and with a resistance element (3; 14, 21) arranged in the circuit and formed on the snap disc, which heats up when a predetermined current flow is exceeded in such a way that the bimetallic disc (6) switches from a low-temperature to a high-temperature position, characterized in that the snap disc (3) is made of material of low electrical conductivity, for example consists of steel or brass, and that an increase in the resistance of the snap disc (3) is brought about by material tapering, preferably by slots (12) in the region of the edges of the snap disc (3). Bimetallschalter, insbesondere stromabhängiger Schalter (1), mit einer Bimetallscheibe (6) und einer von der Bimetallscheibe (6) schaltbaren Schnappscheibe (3), die in einer Schließstellung des Schalters (1) einen Stromfluß bewirkt und in einer Öffnungsstellung den Stromfluß unterbricht, wobei Bimetall- und Schnappscheibe (6, 3) beide in einem Gehäuse (2) angeordnet sind, sowie mit einem im Stromkreis angeordneten und an der Schnappscheibe ausgebildeten Widerstandselement (3; 14, 21), das sich bei Überschreiten eines vorgegebenen Stromflusses derart aufheizt, daß die Bimetallscheibe (6) von einer Niedertemperatur- in eine Hochtemperaturstellung umschaltet, dadurch gekennzeichnet, daß die Schnappscheibe (3) ein Schnappteil (13, 17) umfaßt, auf das als Widerstandselement eine Widerstandsschicht (14, 21) mit definiertem Widerstand aufgebracht ist.Bimetallic switch, in particular current-dependent switch (1), with a bimetallic disc (6) and a snap disc (3) which can be switched by the bimetallic disc (6), which causes a current flow in a closed position of the switch (1) and interrupts the current flow in an open position, whereby Bimetallic and snap disks (6, 3) are both arranged in a housing (2), as well as with a resistance element (3; 14, 21) arranged in the circuit and formed on the snap disk, which is such when a predetermined current flow is exceeded heats up that the bimetallic disc (6) switches from a low temperature to a high temperature position, characterized in that the snap disc (3) comprises a snap part (13, 17) onto which a resistance layer (14, 21) with a defined resistance is applied as a resistance element is. Schalter nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß das Widerstandselement einen Übergangswiderstand > 50 mOhm hat.Switch according to claim 1 or 2, characterized in that the resistance element has a contact resistance> 50 mOhm. Schalter nach Anspruch 3, dadurch gekennzeichnet, daß das Schnappteil (13) einen sehr hohen spezifischen Widerstand aufweist.Switch according to claim 3, characterized in that the snap part (13) has a very high specific resistance. Schalter nach Anspruch 3, dadurch gekennzeichnet, daß das Schnappteil (17) durch Zwischenlage einer Isolierschicht (18) mit der Widerstandsschicht (21) versehen ist, wobei die Isolierschicht (18) das Schnappteil (17) gegen Stromfluß isoliert.Switch according to Claim 3, characterized in that the snap part (17) is provided with the resistance layer (21) by interposing an insulating layer (18), the insulating layer (18) isolating the snap part (17) against current flow. Schalter nach einem der Ansprüche 2 - 5, dadurch gekennzeichnet, daß die Widerstandsschicht (14, 21) durch anodische Lichtbogen-Verdampfung auf das Schnappteil (13, 17) aufgebracht ist.Switch according to one of Claims 2-5, characterized in that the resistance layer (14, 21) is applied to the snap part (13, 17) by anodic arc evaporation. Schalter nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß er achssymmetrisch ausgebildet ist und Bimetallscheibe (6) sowie Schnappscheibe (3) kreisringförmig ausgebildet sind.Switch according to one of the preceding claims, characterized in that it is axially symmetrical and the bimetallic disc (6) and snap disc (3) are circular. Schalter nach einem der vorangehenden Ansprüche, dadurch gekennzeichnet, daß er als selbsthaltender Schalter (1) mit einem zu dem aus Bimetall- und Schnappscheibe (6, 3) gebildeten Schaltwerk parallel geschalteten Widerstand geringerer elektrischer Leitfähigkeit ausgebildet ist.Switch according to one of the preceding claims, characterized in that it is designed as a self-holding switch (1) with a lower electrical conductivity resistor connected in parallel with the switching mechanism formed from the bimetal and snap disk (6, 3).
EP95105956A 1994-04-23 1995-04-21 Current dependent switch Expired - Lifetime EP0678891B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE9406806U 1994-04-23
DE9406806U DE9406806U1 (en) 1994-04-23 1994-04-23 Bimetal switch, in particular current-dependent switch

Publications (2)

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EP0678891A1 true EP0678891A1 (en) 1995-10-25
EP0678891B1 EP0678891B1 (en) 1999-02-17

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ID=6907765

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EP95105956A Expired - Lifetime EP0678891B1 (en) 1994-04-23 1995-04-21 Current dependent switch

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EP (1) EP0678891B1 (en)
AT (1) ATE176832T1 (en)
DE (2) DE9406806U1 (en)
DK (1) DK0678891T3 (en)
ES (1) ES2130462T3 (en)

Cited By (4)

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Publication number Priority date Publication date Assignee Title
DE102011016142A1 (en) * 2011-03-25 2012-09-27 Marcel P. HOFSAESS Temperature-dependent switch with current transfer element
EP2854149A1 (en) * 2013-08-27 2015-04-01 Thermik Gerätebau GmbH Temperature-dependent switch with a snap disc clasped at the edge
IT202100018770A1 (en) 2021-07-15 2023-01-15 Miotti S R L TEMPERATURE LIMITER DEVICE
IT202100018779A1 (en) 2021-07-15 2023-01-15 Miotti S R L TEMPERATURE LIMITER DEVICE

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JP2920103B2 (en) * 1996-01-29 1999-07-19 ウチヤ・サーモスタット株式会社 Thermal protector
DE19604939C2 (en) * 1996-02-10 1999-12-09 Marcel Hofsaes Switch with a temperature-dependent switching mechanism
FR2772980B1 (en) * 1997-12-19 2000-01-21 Schneider Electric Sa MAGNETO-THERMAL TRIGGER DEVICE AND CIRCUIT BREAKER EQUIPPED WITH THIS DEVICE
EP2194555A1 (en) * 2008-12-04 2010-06-09 Abb Ag Actuator for an installation switching device
CN103608886B (en) 2011-06-28 2015-12-23 打矢恒温器株式会社 Motor protector
DE102013102089B4 (en) * 2013-03-04 2015-02-12 Marcel P. HOFSAESS Temperature-dependent switch with insulating washer

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102011016142A1 (en) * 2011-03-25 2012-09-27 Marcel P. HOFSAESS Temperature-dependent switch with current transfer element
EP2854149A1 (en) * 2013-08-27 2015-04-01 Thermik Gerätebau GmbH Temperature-dependent switch with a snap disc clasped at the edge
IT202100018770A1 (en) 2021-07-15 2023-01-15 Miotti S R L TEMPERATURE LIMITER DEVICE
IT202100018779A1 (en) 2021-07-15 2023-01-15 Miotti S R L TEMPERATURE LIMITER DEVICE

Also Published As

Publication number Publication date
ATE176832T1 (en) 1999-03-15
DE59505108D1 (en) 1999-03-25
ES2130462T3 (en) 1999-07-01
DK0678891T3 (en) 1999-05-10
EP0678891B1 (en) 1999-02-17
DE9406806U1 (en) 1995-06-01

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