EP1774555B1 - Bimetallic thermal switch - Google Patents

Abstract

The invention describes a bimetallic thermal switch comprising an electrically insulating carrier ( 2 ), a contact spring ( 4 ) made from a bimetallic material, which is carried by the electrically insulating carrier ( 2 ) and has two ends, one being fixed in position, and which is so formed, at least over a certain portion ( 4 a), that it will abruptly change its curvature when its switching temperature is exceeded; two electric supply lines ( 8, 9 ) held on the insulating carrier ( 2 ) and leading to two contact pieces ( 6, 7 ) disposed separately one from the other and from the contact spring ( 4 ); and a contact bridge ( 5 ) mounted on the contact spring ( 4 ) opposite the two contact pieces ( 6, 7 ).

Description

The invention is based on a bimetallic switch, which in the DE 195 09 656 C2 is disclosed. The known bimetallic switch has in a housing an insulating support in which a metallic support is embedded, which carries a contact spring made of a bimetal. The contact spring is provided at its one end with a contact piece and connected at its opposite, fixed end with a leading out of the housing supply line. From a second contact piece, which is opposite to the first contact piece attached to the contact spring, a second lead leads out of the housing.

Such a bimetallic switch is used to protect electrical equipment, motors, transformers and the like against overheating. He should open when the temperature at his site a predetermined limit exceeds. This limit is hereinafter referred to as the switching temperature. Thus, the bimetallic switch has a well-defined switching temperature, the contact spring is spherically shaped in an area between its fixed end and its contact piece by an embossing process. This has the consequence that the spherically shaped region can not change its curvature steadily, but only by leaps and bounds, when a minimum mechanical stress determined by the shape of the contact spring and its elastic properties has built up due to temperature change in the contact spring. For safety reasons, tolerance limits specified for the switching temperature must be observed.

In the known bimetallic switch, the current consumed by the electrical equipment to be monitored flows through the contact spring. In this case, heat is generated in the contact spring, which depends on the current intensity and the ohmic resistance of the contact spring. This is disadvantageous for some applications, because a temperature can be simulated by the current heat generated in the contact spring, which is higher than the temperature at the location to be monitored of the electrical device. It can therefore come to unwanted tripping of the bimetallic switch. The problem is aggravated by the fact that there is a development in electrical engineering to ever higher power densities. In the case of bimetallic switches, this means that increasingly smaller electrical currents and heat flows must be conducted through smaller and smaller conductor cross-sections, and this also includes the cross-section of a bimetallic contact spring. The problem is further aggravated by the fact that higher power densities require a higher reliability of the bimetallic switches for safety reasons. At the same time, the person responsible for the development of bimetallic switches is asked to provide solutions which, if possible, are not more expensive but cheaper than known solutions.

In order to achieve a reliable switching behavior despite decreasing cable cross-sections and higher power densities, it is known between the two differently composed layers of the bimetallic contact spring, which cause the switching process due to their different thermal expansion coefficient at a temperature change and usually have a relatively high electrical resistance to provide an intermediate layer of a highly electrically conductive metal, in particular of copper. This should increase the electrical conductivity of the contact spring without changing the switching temperature. By this measure, one can mitigate the influence of the current heat on the response of the bimetallic switch, but not eliminate. Unfortunately, this is an expensive measure, because the contact spring is no longer made of a bimetal, but of a trimetal, and because the contact spring adversely changed by the three-layer structure in their mechanical properties.

Another problem arises from the fact that as a result of progressive miniaturization unavoidable manufacturing tolerances in the contact spring and irregularities in the form of the contact spring formed by embossing within a series of Thermobimetallschaltern lead to a dispersion of the switching temperatures, which is greater, the smaller the bimetallic switch become. Although one could counter this by measuring the switching temperatures of all bimetallic switches in a series and reducing the spread within a delivery by sorting the bimetallic switches, this is an extremely uneconomical measure.

Thermobimetallic switches in which the contact spring is not made of a bimetallic strip, but of a highly conductive, spring-hard iron or copper alloy, and in which a separate Bimetallschnappscheibe is provided for actuating the contact spring, which are arranged loosely on the underside or top of the contact spring is, so that the current to be switched with the bimetallic switch current substantially does not flow over the bimetallic strip. Such a bimetallic switch is for example from EP 0 246 255 B1 known. In such a bimetallic switch is indeed the Switching element (the Bimetallschnappscheibe) largely decoupled from the current-carrying element (the contact spring) of the bimetallic switch, but requires such a switch a greater effort in the manufacture of its parts and its assembly, because the bimetallic snap disk to be produced separately, for example between separately punched and to be bent hook and tabs of the contact spring must be used and secured.

From the US 4,843,363 is a three-phase switch with a bimetallic disc known which is in the circuit. Similar to the above-described bimetallic Schatt can therefore also in the from the US 4,843,363 known three-phase switch, the switching temperature can be influenced by current heating, for example, in a damage to the protected by the three-phase switch electrical device.

Furthermore, from the DE 198 27 113 A1 Thermobimetalischalter known, which have a circular in plan metallic housing with an insulating cover, on the inside of a diagonal arrangement two contacts are fixed. The contact pieces is a contact plate opposite, which acts as a contact bridge and can be actuated together with a Bimetallschnappscheibe and arranged between this and the contact plate spring washer. The contact plate, the spring washer and the Bimetallschnappscheibe are centrally riveted together and thus determined in the housing that the spring washer is clamped with its edge between two housing parts. Although in these known bimetallic switches, the power line and the bimetallic disc are largely decoupled from each other, but such a switch is relatively expensive because of the chosen structure and the larger number of parts required for its function in the manufacture of its parts and during assembly.

The present invention has for its object to provide a way how a bimetallic switch can be improved with a fixed at one end contact spring of a bimetallic strip, that it from a minimum number can be produced inexpensively from components in small size and at the same time shows a reliable switching behavior, which is largely unaffected by the current generated in the bimetallic switch current heat.

This object is achieved by a bimetallic switch with the features specified in claim 1. Advantageous developments of the invention are specified in the subclaims.

The bimetallic switch according to the invention has an electrically insulating support, a carrier spring carried by a bimetal, which is formed at least in a portion so that it suddenly changes their curvature when their switching temperature exceeds its curvature, two held by the insulating support electrical leads, which are two of each other and separate from the contact spring contact pieces, and a contact bridge, which is mounted opposite the two contact pieces on the contact spring.

• ◆ Der Thermobimetallschalter besteht aus einer minimalen Anzahl von Bauteilen, nämlich aus zwei Zuleitungen, die zu zwei Kontaktstücken führen, aus einer Kontaktfeder aus einem Thermobimetall und aus einem elektrisch isolierenden Träger, welcher diese drei Elemente trägt. Es scheint nicht möglich zu sein, mit weniger Einzelteilen auszukommen.
• ◆ Die geringe Anzahl von Einzelteilen begünstigt eine rationelle, automatisierungsgerechte Fertigung.
• ◆ Der elektrisch isolierende Träger kann preiswert durch Spritzgießen aus Kunststoff geformt werden.
• ◆ Die Zuleitungen und die Kontaktfeder können in den isolierenden Träger eingebettet werden, insbesondere dadurch, dass sie mit Kunststoff umspritzt werden. Es ist aber auch möglich, den isolierenden Träger aus zwei miteinander zu verbindenden Teilen herzustellen, zwischen welchen die Zuleitungen und die Kontaktfeder zum Beispiel durch Verrasten formschlüssig fixiert werden. Die beiden Teile des isolierenden Trägers können untereinander gleich ausgebildet sein, so dass sie sich symmetrisch zusammenfügen lassen.
• ◆ Die Zuleitungen mit ihren Kontaktstücken und die Bimetallkontaktfeder können aus vorgestanztem bandförmigem Halbzeug gebildet werden. Das ist für eine automatisierte Fertigung günstig. Die Kontaktstücke und die Kontaktbrücke können bereits auf dem bandförmigen Halbzeug durch Nieten, Löten oder Schweißen befestigt werden. So kann man zum Beispiel ein Bimetallband durchgehend durch Rollnahtschweißen mit einem Kontaktprofil für die Kontaktbrücke versehen. Aus einem solchen Halbzeug lassen sich anschließend durch Prägen und Stanzen einzelne Kontaktfedern bilden. Entsprechend lassen sich die Zuleitungen zu den Kontaktstücken aus einem bandförmigen Halbzeug bilden. Für die Herstellung der Zuleitungen können aber auch einzelne Kontaktstücke auf das Halbzeug geschweißt, gelötet oder genietet werden. Für das Schalten geringerer Ströme geeignete Kontaktschichten können durch galvanische Metallbeschichtung gebildet werden.
• ◆ Obwohl der erfindungsgemäße Thermobimetallschalter eine Thermobimetallkontaktfeder hat, welche die zu schaltenden Ströme direkt schaltet, beeinflußt der durch den Schalter fließende Strom das Schaltverhaltenpraktisch nicht, weil der Strom im wesentlichen auf kürzestem Wege von dem einen Kontaktstück über die Kontaktbrücke zu dem anderen Kontaktstück fließt und die Kontaktbrücke ohne Rücksicht darauf, woraus die Thermobimetallkontaktfeder besteht, aus einem elektrisch gut leitenden Werkstoff, insbesondere auf der Basis von Kupfer oder Silber, bestehen und ohne nachteilige Folgen für das Schaltverhalten der Bimetallkontaktfeder selbst im Falle einer Miniaturisierung des Schalters einen hinreichend großen Leitungsquerschnitt haben kann.
• ◆ Anders als bei einer mittig gehaltenen Bimetallschnappscheibe kann in einem erfindungsgemäßen Thermobimetallschalter eine Kontaktfeder verwendet werden, welche an einem Ende festgelegt ist und am gegenüberliegenden Ende den Schalter öffnet oder schließt. Beim Öffnen des Schalters erzielt man dadurch einen größeren Kontaktabstand als man ihn bei Verwendung einer gleich langen, mittig befestigten Schnappscheibe erzielen kann. Das ist für miniaturisierte Schalter, bei denen kurze Kontaktfedern angestrebt werden, von besonderer Bedeutung.

This has significant advantages:

• ◆ The bimetallic switch consists of a minimum number of components, namely two leads, which lead to two contact pieces, a contact spring made of a bimetallic strip and an electrically insulating support, which carries these three elements. It does not seem possible to get along with fewer items.
• ◆ The small number of individual parts favors a rational, automation-compatible production.
• ◆ The electrically insulating carrier can be inexpensively molded by plastic injection molding.
• ◆ The leads and the contact spring can be embedded in the insulating support, in particular by being overmoulded with plastic. But it is also possible to produce the insulating support of two parts to be joined together, between which the leads and the contact spring are positively fixed, for example by locking. The two parts of the insulating support may be identical to each other, so that they can be assembled symmetrically.
• ◆ The leads with their contact pieces and the bimetal contact spring can be formed from pre-punched band-shaped semi-finished product. This is favorable for an automated production. The contact pieces and the contact bridge can already be fastened on the band-shaped semifinished product by riveting, soldering or welding. So you can, for example, a bimetallic band continuously provided by seam welding with a contact profile for the contact bridge. From such a semifinished product can then be formed by embossing and punching individual contact springs. Accordingly, the leads to the contact pieces can form a strip-shaped semifinished product. For the production of the leads but also individual contact pieces can be welded, soldered or riveted to the semi-finished product. Contact layers suitable for switching lower currents can be formed by galvanic metal coating.
• ◆ Although the bimetallic switch according to the invention has a bimetallic contact spring, which switches the currents to be switched directly, the current flowing through the switch does not affect the switching behavior practically, because the current flows in the shortest path from one contact piece via the contact bridge to the other contact piece and the Contact bridge without regard to what the Thermobimetallkontaktfeder consists of a highly electrically conductive material, in particular based on copper or silver, and without adverse consequences for the switching behavior of the bimetallic contact even in the case of miniaturization of the switch can have a sufficiently large line cross-section.
• Unlike a centrally held bimetallic snap-action disc, in a bimetallic switch according to the invention a contact spring can be used which is fixed at one end and opens or closes the switch at the opposite end. When you open the switch to achieve a larger contact distance than you can achieve it when using a same length, centrally mounted snap disk. This is for miniaturized switches, in which short contact springs are sought, of particular importance.

In the bimetallic switch according to the invention, the contact spring may be formed in a known manner, in particular be bulged by embossing, in order to achieve that it changes its curvature when its switching temperature is exceeded. This shaping expediently takes place only in a central portion of the contact spring. The contact bridge is preferably arranged on the contact spring outside of the region which changes its curvature as a consequence of its shape, preferably directly on the movable end of the contact spring.

As a contact bridge is particularly suitable a profile section of a highly electrically conductive contact material, in particular based on copper or silver. The contact bridge is suitably fastened by riveting, welding or soldering on the contact spring, preferably already in the course of the production of a band-shaped semi-finished product, from which the contact springs provided with a contact bridge are formed by embossing, punching and optionally by bending. However, the contact bridge does not have to be fixed rigidly on the contact spring. It can also be attached to the contact spring in the manner of a rocker by being connected to the center of the contact spring with some play, for example by means of a clamp or a rivet. Such an embodiment has the advantage that it can compensate for misalignments of the contact bridge and / or the contact pieces and can ensure that the contact bridge equally well contacts two contact pieces.

The contact spring may be attached with its fixed end directly to the insulating support. Such an embodiment is particularly suitable for air-open switch, the rear derailleur is not protected by a housing. For bimetallic switch, in which the switching mechanism is located in a housing, it is preferred that the contact spring not directly, but only indirectly to be attached to the electrically insulating support, in particular so that the contact spring is connected with its remote from the contact bridge end by welding, soldering, clamping, crimping or riveting with a metallic support, which in turn is held by the insulating support. The metallic carrier should be characterized by a greater rigidity than it has the contact spring, so that the switching behavior and the switching path are not affected by unintentional bending of the metallic carrier. The metallic carrier itself is expediently embedded with a part of itself in the insulating carrier so that it is firmly anchored therein.

Preferably, the metallic support is fixedly connected to the insulating support at two spaced apart locations. This gives the metallic carrier improved flexural rigidity and torsional rigidity. This can be further improved in that the metallic support is U-shaped in plan view and the two legs of the U are attached to the insulating support, in particular embedded. It is particularly advantageous if the legs have an opposite surface to the base of the U angled surface and the fixed end of the contact spring is attached to the base connecting the legs of the U.

The legs of the U preferably run on the lateral walls of a flat housing and can increase its dimensional stability against external pressure, which is important in some applications of bimetallic switches.

The use of a metallic carrier for the bimetallic contact spring has the further advantage that the fixed end of the contact spring can be arranged at the remote from the insulating support end of the housing, whereas the free end of the contact spring is located with the contact bridge in the vicinity of the insulating support. This makes it easier for the two contact pieces, with which the contact bridge is to work together, at well-defined locations position, for which you only need exceptionally short leads, which only need to protrude with a short stub over the insulating support. As a result, very stable arrangements are obtained even in the case of miniaturized switches. In addition, erroneous positioning of the contact pieces is unlikely with short leads, whereby an automated production is favored.

The housing of the bimetallic thermal switch may be made of metal or plastic. A metallic housing is preferred. For the metallic carrier of the contact spring, it is preferred that it is insulated from the housing. However, the invention also allows an embodiment in which the metallic carrier of the contact spring contacts the metallic housing or is otherwise electrically conductively connected to it. The advantage of this is that it allows the use of the bimetal temperature switch in a star connection, in which an electrical contact is made not only on the leads leading to the two fixed contact pieces of the switch, but also on the housing.

The leads to the contact pieces are expediently embedded in the insulating support as well as the legs of the metallic support. Preferably, the switch is constructed mirror-symmetrically with respect to the two contact pieces or the electrical leads carrying them.

In the case of a switch provided with a housing, the electrically insulating support expediently serves at the same time for closing the housing by being inserted and fixed in it from one end. It can be fixed, for example, by gluing, by clamping, by crimping the edge of the housing against the insulating support or by ultrasonic welding. In addition, a sealing of the housing by casting a possibly remaining after insertion of the electrically insulating support opening of the housing by means of a hardening sealing compound possible. In cases where sealing is not important, the switch can also be protected, as known per se, only by means of a shrunk-on shrink-tubing section, which also offers protection against the contact with live electrical connections.

Figur 1

zeigt einen erfindungsgemäßen Schalter in einer Draufsicht auf sein Schaltwerk bei geschnittenem Gehäuse,

Figur 2

zeigt einen Längsschnitt gemäß Schnittlinie II-II durch den in Figur 1 dargestellten Schalter, wobei die Kontakte geschlossen sind,

Figur 3

zeigt die Darstellung entsprechend Figur 2 bei geöffneten Kontakten,

Figur 4

zeigt eine Abwandlung des Schalters aus Figur 1 in einem Querschnitt entlang der Schnittlinie IV-IV in Figur 1 bei geschlossenem Schalter,

Figur 5

zeigt einen Schnitt entsprechend Figur 4, jedoch bei offenem Schalter und

Figur 6

zeigt ein drittes Beispiel eines erfindungsgemäßen Schalters in einer Darstellung entsprechend der Figur 1.

Embodiments of the invention are illustrated in the accompanying drawings. Like or corresponding parts are designated in the examples with corresponding reference numerals.

FIG. 1

shows a switch according to the invention in a plan view of its rear derailleur with cut housing,

FIG. 2

shows a longitudinal section along section line II-II through the in FIG. 1 illustrated switch, wherein the contacts are closed,

FIG. 3

shows the representation accordingly FIG. 2 with open contacts,

FIG. 4

shows a modification of the switch FIG. 1 in a cross section along the section line IV-IV in FIG. 1 with the switch closed,

FIG. 5

shows a section accordingly FIG. 4 , but with open switch and

FIG. 6

shows a third example of a switch according to the invention in a representation corresponding to FIG. 1 ,

The Thermobimetallschalter show the FIGS. 1 to 3 greatly enlarged (scale approximately 10: 1). He has a flat housing 1, which may be made of metal or plastic and at one end has an opening which through a insulating support 2 is closed. The insulating support 2 is a molded part made of plastic, which has a flange 2a which lies outside the housing 1 and an inner part 2b which engages in a form-fitting manner in the housing 1. The flange 2 a strikes the edge of the opening of the housing 1. The inner part 2 b has lateral extensions 2 c, which rest against the low side walls 1 a of the housing 1.

In the housing 1, a metallic support 3 is arranged, which is formed in the plan view substantially U-shaped. Accordingly, it has a base 3a and two legs 3b extending from this base 3a. In addition, a stubby projection 3c extends centrally from the base 3a, in a direction opposite to the direction of the legs 3b. On the extension 3c are by soldering or welding a contact spring 4 made of a bimetal, which extends parallel to the legs 3b in the direction thereof, as well as a trim bracket 10, which is dispensable. Instead of soldering or welding, the contact spring 4 could also be fastened by riveting, clamping or crimping. The metallic carrier 3 may be formed by punching and bending from a metal sheet. His legs 3b are bent relative to the base 3a at a right angle, parallel to the side walls 1 a of the housing 1 and extend in the region of the extensions 2c in the insulating support 2 inside, in which they are embedded and preferably by undercuts, which at the embedded portions of the legs 3b are formed, are anchored in the extensions 2c. The insulating support 2 and the metallic carrier 3 form in the manner described a stable assembly, which is particularly well suited as a basis for the construction of the switching mechanism of the bimetallic switch.

The contact spring 4 is provided at its movable end with a contact bridge 5, which extends transversely to the longitudinal direction of the legs 3b and the contact spring 4 and is fastened by riveting, soldering or welding on the contact spring. In the middle region of the contact spring 4, between the stubby Extension 3c and the movable end, on which the contact bridge 5 is located, which is the contact spring 4 with a convex embossing 4a of approximately circular outline 4b provided. By this shaping, it is achieved that the bimetallic switch opens or closes abruptly when its switching temperature is exceeded. Instead of the illustrated crowned embossing 4a, the contact spring 4 can also be stamped into a differently shaped bulge, if this leads to a sudden change in the curvature of the contact spring 4 only when the switching temperature is exceeded; For example, the bulge may have a trapezoidal shape across the surface of the contact spring in section.

The contact bridge 5 are two contact pieces 6 and 7 opposite. The insulating support 2 carries these two contact pieces 6 and 7 separated from each other by two metallic, formed from sheet metal leads 8 and 9 are embedded in the carrier 2 so that they protrude each with its two ends from the carrier 2. On the projecting into the housing 1 portions of the leads 8 and 9 are the two contact pieces 6 and 7. On the opposite side of the insulating support 2, the two leads 8 and 9 each form a terminal lug 8a and 9a, which later, for example, flexible Connecting cables can be attached.

The switch shown can be produced in a miniaturized version. It consists of a minimal number of parts, which are favorable for an automated assembly. Even with a miniaturized design, the current flowing through the switch practically does not influence the switching behavior.

The FIGS. 4 and 5 show a modified embodiment of the in the FIGS. 1 to 3 illustrated switch. The modification consists in that the contact bridge 5 is not rigidly connected to the contact spring 4, but in the manner of a rocker. For this purpose, the rectangular in plan view contact bridge 5 on its side facing the contact spring 4 side centered a projection 5a a mushroom-shaped extension 5b, which consists of a neck 5c and a head 5d. The neck 5c is caught in a mating hole 4c with some play. The hole 4c and the neck 5c have a shape deviating from the circular shape; they preferably have a rectangular outline, so that the contact bridge 5 on the contact spring 4 can not rotate. The contact bridge 5 can be attached, for example, to the contact spring 4 by first forming only the neck 5c on the projection 5b, inserting it into the hole 4c punched in the contact spring 4, and then by means of a forming tool which forms a die with the die has the head 5d defining contour, similar to rivets formed the head 5d.

This embodiment has the advantage that misalignments between the contact bridge 5 and the two contact pieces 6 and 7 in the way they are in FIG. 5 is shown, due to the possible rocking motion can compensate automatically, so that it comes in any case to a full-surface contact of the contact bridge 5 with the two contact pieces 6 and 7, as in FIG. 4 shown.

This in FIG. 6 illustrated embodiment differs from that in the FIGS. 1 to 3 illustrated embodiment in that from the legs 3b of the metallic support 3 in each case a tongue 3d is cut out. The two tongues 3d are bent outward and are the side walls 1a of the housing 1, which in this case consists of metal, with mechanical bias, so that the metallic support 3 and the housing 1 are always at the same electrical potential. This allows the use of the bimetallic thermal switch in a star connection, in which an electrical contact is made not only at the two terminal lugs 8a and 9a, but also on the housing 1.

LIST OF REFERENCE NUMBERS:

1.

casing

1a.

side walls

Second

carrier

2a.

flange

2c.

inner part

2 B.

extension

Third

carrier

3a.

Base

3b.

leg

3c.

extension

3d.

tongue

4th

contact spring

4a.

embossing

4b.

outline

4c.

hole

5th

Contact bridge

5a.

approach

5b.

mushroom-shaped extension

5c.

neck

5d.

head

6th

contact piece

7th

contact piece

8th.

supply

8a.

terminal lug

9th

supply

9a.

terminal lug

10th

trim bracket

Claims (25)

1. A bimetallic thermal switch comprising
   an electrically insulating carrier (2);
   a contact spring (4) made from a bimetallic material, which is carried by the electrically insulating carrier (2) and has two ends, one being fixed in position, and which is so formed, at least over a certain portion (4a), that it will abruptly change its curvature when its switching temperature is exceeded;
   two electric supply lines (8, 9) held on the insulating carrier (2) that lead to two contact pieces (6, 7) disposed separately one from the other and from the contact spring (4);
   and a contact bridge (5) mounted on the contact spring (4) opposite the two contact pieces (6, 7).
2. The bimetallic thermal switch as defined in Claim 1, characterized in that the contact bridge (5) is mounted on the contact spring (4) outside of that portion (4a) which due to its particular shape changes its curvature abruptly.
3. The bimetallic thermal switch as defined in Claim 1 or Claim 2, characterized in that the contact bridge (5) is a section cut from a profiled material.
4. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the contact bridge (5) is fixed on the contact spring (4) by welding, clamping, crimping, riveting or soldering, welding and riveting being preferred for that purpose.
5. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the contact spring (4) is fixed on the insulating carrier (2) directly with its end remote from the contact bridge (5).
6. The bimetallic thermal switch as defined in any of Claims 1 to 4, characterized in that the contact spring (4) is fixed indirectly on the electrically insulating carrier (2).
7. The bimetallic thermal switch as defined in Claim 6, characterized in that the contact spring (4) is fixed on a metallic carrier (3) with its end remote from the contact bridge (5), the metallic carrier being itself carried by the insulating carrier (2).
8. The bimetallic thermal switch as defined in Claim 7, characterized in that a portion of the metallic carrier (3) is embedded in the insulating carrier (2).
9. The bimetallic thermal switch as defined in Claim 8, characterized in that a positive fit exists between the metallic carrier (3) and the insulating carrier (2).
10. The bimetallic thermal switch as defined in Claim 7, 8 or 9, characterized in that the metallic carrier (3) is rigidly connected with the insulating carrier (2) at two points that are spaced one from the other.
11. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the supply lines (8, 9) are embedded in the insulating carrier (2).
12. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the switch comprises a housing (1) that accommodates a switching mechanism comprising the contact spring (4) with the contact bridge (5), the contact pieces (6, 7) located opposite the latter and the insulating carrier (2).
13. The bimetallic thermal switch as defined in Claim 12, characterized in that the housing (1) is made from metal.
14. The bimetallic thermal switch as defined in Claims 7 and 13, characterized in that the metallic carrier (3) is electrically insulated from the housing (1).
15. The bimetallic thermal switch as defined in Claims 7 and 13, characterized in that the metallic carrier (3) is connected with the housing (1) in an electrically conductive way.
16. The bimetallic thermal switch as defined in Claim 15, characterized in that the metallic carrier (3) is in contact with the housing (1).
17. The bimetallic thermal switch as defined in Claim 12, characterized in that the housing (1) is made electrically insulating.
18. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that it has a mirror-symmetrical design as far as the position of the two contact pieces (6,7) is concerned.
19. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that it has a mirror-symmetrical design as far as the position of its two supply lines (8, 9) is concerned.
20. The bimetallic thermal switch as defined in any of the preceding claims, in combination with Claim 7, characterized in that the metallic carrier (3) has the shape of a U, when viewed from the top, and has its two legs (3b) of the U embedded in the insulating carrier (2).
21. The bimetallic thermal switch as defined in Claim 20, characterized in that the contact spring (4) is attached to the base (3a) of the U that connects the legs (3b).
22. The bimetallic thermal switch as defined in Claim 20 or Claim 21, characterized in that the legs (3b) have a surface that is bent off relative to the base (3a) of the U.
23. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the contact bridge (5) consists of a material of higher electric conductivity than the bimetal of the contact spring (4).
24. The bimetallic thermal switch as defined in any of Claims 20 to 22, in combination with Claim 11, characterized in that the legs (3b) of the U are located close to the oppositely arranged side walls (1 a) of the housing (1).
25. The bimetallic thermal switch as defined in any of the preceding claims, characterized in that the contact bridge (5) is mounted on the contact spring (4) in the way of a rocker.

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