EP2304757B1 - Bimetallic part and temperature-dependent switch equipped therewith - Google Patents

Description

The present invention relates to a bimetal part for use as an active switching element in a temperature-dependent switch and equipped with the bimetal temperature-dependent switch.

The GB 2 325 345 A as well as that US 1 668 973 A describe in each case such a bimetal part, which has at least one inner region and an outer region surrounding the at least one inner region, wherein inner and outer regions are formed integrally with each other in sections and mechanically separated from each other in sections, and wherein at least one contact surface is provided on the inner region ,

The known bimetal parts are formed as an approximately rectangular bimetallic spring with two outer webs and an inner web extending therebetween, wherein in the webs curved portions are provided, which cause the outer webs and the inner web each have different lengths.

In the context of the present invention, a bimetal part is understood as meaning a multilayer active, sheet-metal component made of two, three or four components which are inseparably connected to one another and have different coefficients of expansion. The connection of the individual layers of metals or metal alloys are cohesively or positively and are achieved for example by rolling.

Such bimetal parts are commercially available as sheets, see for example the company G. Rau GmbH & Co. KG, Kaiser-Friedrich-Str. 7, 75172 Pforzheim, as well as their corresponding Internet presence under www.rau-pforzheim.de.

From the EP 0 658 911 B1 It is known in this context to use multi-layer bimetallic parts as springs and discs in temperature-dependent switches, with an increase in the possible nominal currents and the switching hysteresis should be achieved by appropriate choice of material and composition.

The bimetallic part is part of a temperature-dependent switching mechanism which establishes or opens an electrically conductive connection as a function of its temperature between two fixed contact parts provided on the switch.

From the prior art, such temperature-dependent switches are known in different constructions.

The bimetal is usually designed as a cantilever spring or as a loosely inserted disc.

If the bimetal part as in the DE 198 16 807 A1 is designed as a bimetallic spring tongue, so it carries at its free end a movable contact part, which cooperates with a fixed contact part. The fixed contact part is electrically connected to a first outer terminal, wherein a second outer terminal is electrically connected to the clamped end of the bimetallic spring tongue.

Below its response temperature, the bimetallic spring tongue closes the electrical circuit between the two outer terminals by pressing the movable contact part against the fixed contact part.

As the temperature of the bimetal tongue increases, it begins to stretch and deform in a creep until it finally reaches its open position umspringt in which it lifts the movable contact part of the fixed contact part. In this creep phase, the contact pressure decreases, which can lead to the formation of arcing, contact erosion and contact flutter.

On the other hand, if the bimetallic part is designed as a bimetallic disc, it generally interacts with a spring snap-action disc which carries the movable contact part which cooperates with the fixed contact part in the manner described above. The spring snap disc is supported by its edge on an electrode which is connected to the second external connection. Such a switch is for example in the DE 21 21 802 A or the DE 196 09 310 A1 described.

Below its response temperature, the bimetallic disc is loosely inserted, so it is mechanically unloaded. The contact pressure between the fixed and movable contact part and thus the electrical connection between the two outer terminals is provided via the spring snap disk. Increases the temperature of the known temperature-dependent switch, so the bimetal passes through a creep phase in which it gradually deforms until it then jumps abruptly into its open position in which it acts on the Federschnappscheibe that they the movable contact part of the fixed contact part takes off and thus opens the known switch. Here, the creep phase has no negative impact on the contact pressure.

In the switch described above with the bimetallic spring tongue, the bimetal part itself is current-flowed, so that it heats up by the current flowing through the switch. In this way, the known switch not only reacts to external temperature increases, it also responds to a high current flow.

Such switches therefore react temperature-dependent and current-dependent.

In contrast, in the bimetal disc switch, the bimetal part always has no current, so it does not heat up due to the flowing current, so that such switches switch largely independent of current.

But there are also switches are known in which a bimetallic spring tongue cooperates with a Federschnappteil, which carries the flowing current, so that in these constructions, the bimetallic spring tongue itself carries no electricity. Conversely, switches are also known in which a bimetallic disc carries the movable contact part and thus current flows through it.

Finally, temperature-dependent switches with two external terminals are known, which are each connected to a fixed contact part, wherein an electrically conductive contact bridge is provided, which carries the flowing current when it rests against the fixed contact parts.

Such switches with contact bridge are eg in the DE 197 08 436 A1 described. They are intended for applications in which high rated currents flow through the switch, which would lead to a heavy load or self-heating of a live spring snap or bimetal part.

The contact bridge is supported by a Federschnappscheibe, which cooperates with a bimetallic disc. If the bimetal disc is below its response temperature, it is exposed without mechanical load in the switch, the spring snap disc presses the contact bridge against the fixed contact parts, so that the circuit is closed. When the temperature increases, the bimetallic disc snaps from its force-free closed position to its open position in which it works against the spring snap disc and lifts the contact bridge of the fixed contact parts.

Also in this switch construction, the above-mentioned problems associated with the creep phase of the bimetallic disc occur when they are instantaneous carries the contact bridge and ensures the contact pressure. Therefore, the spring snap disk is provided in the known switch, which maintains the contact pressure unchanged in the creep phase of the bimetallic disc.

The switches described so far are used to protect electrical equipment such as hair dryers, motors of alkaline pumps, irons, etc. from excessive temperature and possibly high current. For this purpose, the known switches are connected with their external terminals in series in the supply circuit of the electrical equipment to be protected and also thermally coupled to the device to be protected.

If the temperature of the device to be protected increases beyond the switching temperature of the bimetal part, the temperature-dependent switch opens the circuit and the protected device can cool down again.

In order to prevent restarting after cooling of the device and thus also of the bimetal part, it is also known to associate the temperature-dependent switch with a parallel resistor, which passes a residual current when the switch is open, which heats the resistor far enough that the switch remains open. Such switches are referred to as latching switches.

Furthermore, it is known to provide the known switch with a defined current dependence by a heating resistor is connected in series with the outer terminals, which is traversed by the operating current of the protected electrical device and heated at high operating current defines and ensures that Switch is opened, as well as the bimetal heated accordingly.

Both on switches with current-carrying bimetallic as well as switches with power-free bimetal part, the switching temperature is crucial for the provided by the switch safety function. For different applications the switching temperature must have different values, which, however, must fluctuate only within narrow limits in order to provide the desired safety.

Against this background, in the design of such temperature-dependent switches greatest attention is paid to compliance with the critical temperature.

In this case, temperature-dependent switches with non-current-carrying bimetallic part are preferred because they have a more constant switching temperature. This is u.a. the fact that the bimetal is mechanically free of forces in the closed position, so that it is exposed to significantly lower aging processes than a bimetallic, which must ensure in the closed position for the contact pressure, which takes over the spring snap part in the other constructions.

In particular, in the case of current-carrying bimetal parts, the creep phase mentioned above is disadvantageous because, in the creep phase, the bimetallic part stretches unpredictably, as a result of which the contact pressure wears off. This can lead to unwanted contact flicker and thus undesirable contact erosion.

To eliminate these problems, current-carrying bimetal parts are provided with indentations that largely suppress the creep phase. These impressions ensure that the length expansions of the two metal layers compensate each other below the desired transition temperature. However, this leads to mechanical stresses within the bimetal parts, which in turn adversely affects the aging process.

These problems do not occur in the loose inserted bimetal parts, because there it is not necessary to suppress the creep phase.

However, the switch variants with bimetallic disc and spring snap disc have the disadvantage that the bimetallic disc and the spring snap disc with respect to their mechanical and electrical properties each newly matched must be designed when designing switches with other transition temperatures or other allowable operating currents.

Another disadvantage of the switches with Federschnappscheibe and bimetallic disc is seen in the variety of required components, which also provides a height that can be problematic in certain applications.

From the DE 1 590 324 A a bimetal part for a temperature-dependent switch is known, which is formed as an elongated rectangle and is firmly clamped at its one narrow end, while it carries at its other narrow end a movable contact part, which cooperates with a fixed contact part such that when the switch is closed, the operating current of to be protected device flows through the bimetal and the two then in contact with each other contact parts.

The longitudinal sides of the bimetallic part are folded over so that the bimetal part is double-layered over approximately one quarter of its width on both longitudinal sides. Between the movable contact part and about half the length of the bimetal part, the upper layer of the double-layered longitudinal sides is removed by punching out rectangles which extend over approximately one quarter of the width of the bimetal part. In this way, in the lower layer single-layer side bars are formed, which define between them a central web in the upper position, which occupies half the width of the bimetallic part. The side bars are shortened by V-shaped embossing, so that the middle bar protrudes.

As the temperature increases, the center bar bends opposite to the bend of the remaining bimetal part, thus snapping between the side bars. In this way, the temperature interval is to be reduced, within which the bimetal part snaps between its low temperature and its high temperature position.

Due to the partly single-layered and partly double-layered structure of the well-known bimetal part as well as the shortening of the side bars, the actuating forces in the middle bar and in the side bars are very different. Furthermore, the structure is mechanically complex and weakened in its strength by the two punched rectangles.

This means that the known bimetallic part is not exactly adjustable with respect to its transition temperature, wherein the transition temperature is not long-term stability because of the mechanical asymmetric loads.

Furthermore, the known bimetallic only as a cantilevered, current-carrying bimetallic spring can be used, which is associated with the disadvantages described above.

A similar bimetal part describes the US 2 249 837 A , The known bimetallic is formed in one layer as an elongated rectangle and is firmly clamped at its one narrow end, while it carries at its other narrow end a movable contact part, which cooperates with a fixed contact part such that when the switch is closed, the operating current of the device to be protected by the bimetal flows.

The bimetal part is divided by two longitudinal slots in a central web and two outer webs, wherein the webs at the narrow ends of the bimetallic integral with each other. The bimetallic part is deformed by bending and heat treatment so that the central web is curved down more than the two outer webs.

By adjusting the relative height of the fixed contact member to the clamped narrow end of the bimetallic member, the curvature of the central web is further adjusted as compared to the bending of the outer members, thereby changing the opening temperature of the bimetallic member-equipped temperature-dependent switch.

Also, this known bimetallic is used only as a cantilevered, current-carrying bimetallic spring, which is associated with the disadvantages described above. Furthermore, the opening temperature must be adjusted by subsequent adjustments, which is also disadvantageous.

Due to the different curvature of the central web on the one hand and the side webs on the other hand, the restoring forces in the center bar and in the side bars are very different. This means that in the known the critical temperature is not long-term stability because of the mechanical asymmetric loads.

Against this background, the present invention has the object, the bimetal mentioned above and the aforementioned temperature-dependent switch in such a way that the disadvantages encountered in the prior art are avoided, the mechanical design of the switch should be simple and inexpensive.

According to the invention, this object is achieved in the bimetallic part mentioned above in that the inner region and the outer region are provided with impressions in the form of cups (dimples) from different sides in such a way that their creep phases are suppressed, with the inner and outer regions being the same have mechanical properties.

The object underlying the invention is completely solved in this way.

Namely, the inventor of the present application has recognized that it is possible for bit metal parts, so to speak to provide an internal counterforce, in that the inner and the outer region deform oppositely in the region of the switching point. This is achieved by the opposing embossing as well as by the fact that inner and outer area are mechanically separated in sections, so that they There can move freely against each other there, on the other hand, but also in sections integrally formed with each other, so that they can not move against each other in the longitudinal or radial direction.

According to the inventor, this leads to the fact that the slow phases are blocked as it were. The switching point is long-term stable and is not affected by mechanical loads, current flow or aging processes. Furthermore, the conformational change between high and low temperature position is very abrupt. Finally, no or only a negligible switching hysteresis occurs.

Because the contact surface is provided on the inner portion, the bimetallic member may be firmly clamped to the outer portion at a plurality of locations so as to be limited in its longitudinal or radial extent. Thus, an opposite bending of inner and outer region is enforced, the bimetal is designed as a whole symmetrical, resulting in favorable mechanical conditions and uniform mechanical loads.

Furthermore, the movements of the inner and outer area at the transition between high and low temperature position are not only in opposite directions, the paths to be traveled when bending through the areas are also the same size, which is due to the opposing imprint.

All this means that equipped with the new bimetal part temperature-dependent switch over many switching cycles very reliable and reproducible switch.

How bimetal parts are provided with embossing is well known in the art. In the context of the present invention, "oppositely embossed" is understood to mean that inner and outer regions are provided on different sides with indentations, also referred to as cups or dimples, whose openings thus lie on different sides of the bimetal part.

The new bimetallic part can be used in all switch designs mentioned at the beginning, the disclosures of DE 197 08 436 A1 . DE 21 21 802 A . DE 196 09 310 A1 and DE 198 16 807 A1 are therefore expressly made the subject of the present application.

The new bimetal part can be used without current or current flowing through, but it is not used as a cantilevered bimetallic spring, so it does not have the associated disadvantages.

Against this background, the present invention also relates to a temperature-dependent switch with two external connections and a temperature-dependent switching mechanism which establishes or opens an electrically conductive connection as a function of its temperature between the two external terminals, wherein in the switching mechanism, the new bimetal is provided as an active switching element.

A major advantage of the new switch is that it can dispense with spring snap discs, so that the new switch can be constructed with few components and low overall height.

A further advantage is the fact that switches with different response temperatures and rated currents can now be of identical mechanical construction, only the respective bimetal part must be designed differently according to the transition temperatures and rated currents. A vote between a temperature-dependent switching bimetal and a spring snap as in the prior art is no longer required.

Thus, an existing product range can also be subsequently expanded without problems by further bimetal parts are developed and installed.

On the one hand, it is accordingly preferred if the bimetallic part is connected via its one area to one of the two external connections, and to its another area, preferably via a movable contact part, cooperates with a fixed contact part, which communicates with the other external connection.

In an alternative, the derailleur comprises a spring tongue which communicates at its fixed end with one of the two outer terminals and carries at its free end a movable contact part which cooperates with a fixed contact part which communicates with the other outer terminal, wherein upon reaching a switching temperature, the bimetal part cooperates with the spring tongue such that the movable contact part is lifted off the fixed contact part.

These are the two "classic" design variants for temperature-dependent switches, which now both make use of the bimetal part according to the invention.

In this case, design variants with current-carrying bimetal have the further advantage that the contract pressure is applied by the bimetal, so that the switch is simple and built with low height.

Further, it is preferred if the bimetallic part carries at its one area a contact bridge which cooperates with two fixed contact parts which are in each case in communication with one of the outer terminals.

With this use of the bimetallic part according to the invention, the contact bridge can be supported directly by the bimetallic part, since it can ensure a permanently good contact pressure between the contact bridge and the stationary contacts because of the improved aging resistance, as long as the temperature remains below the response or Aufschnapptemperatur the bimetal. The Federschnappscheibe previously used in the art is no longer required.

The bimetallic part may be formed as an approximately rectangular spring, which preferably comprises at least one extending in the longitudinal direction of the spring inner web and the outer region at least two extending in the longitudinal direction of the spring outer webs as the inner region, which receive the inner web between them and are separated by this over a respective longitudinally extending (L) gap, wherein more preferably, the inner web has comparable mechanical properties, such as the outer webs together.

By these measures, an active switching element is created, which does not change its mechanical and electrical properties even after many switching cycles and switches almost without creep, so that the disadvantages associated with the slow phase in the prior art disadvantages are avoided.

Alternatively, it is preferred if the bimetal part is formed as a disc, wherein preferably the inner region is surrounded by a gap which is interrupted in sections, and further preferably the gap is serrated, meandering or undulating, wherein the inner region preferably has comparable mechanical properties like the outer area.

These measures also create a long-term stable active switching element.

In general, it is preferred if the inner region carries a movable contact part, which is preferably fixed in a form-locking or force-locking manner, and on which the at least one contact surface is formed, or carries a contact bridge with two contact surfaces, or if the contact surface is integrated in the one region ,

Both measures provide for a good electrical contact with a mating contact with which the contact surface cooperates.

If a contact part is used for this purpose, which is fixed in a form-fitting or force-locking manner, then the mechanical properties of the bimetallic part thereby become considerably less affected than if the contact part - as in the prior art - was materially connected to the bimetallic part, which is done there in particular by welding. However, according to the inventor of the present application, this cohesive connection has the disadvantage that the mechanical and electrical properties of the bimetal part are subsequently changed unpredictably.

These problems occur in the non-positive or positive connection, which can be achieved for example by gluing, riveting or clamping, no longer.

With the positive or non-positive connection of the movable contact part with the bimetallic part so the advantage is associated that the once set mechanical and electrical properties of the bimetallic will not be subsequently changed.

This measure thus ensures further stability and reliability of the switching point.

Special advantages, however, arise when the contact surface is integrated in one area. Because then can be dispensed with the separate movable contact part, which brings cost advantages and mounting advantages.

The integrated contact surface influences the mechanical properties of the flexible bimetallic much lower than a positive or non-positively attached contact part.

This integrated interface is also novel and inventive in its own right. Against this background, the present invention also relates to a bimetal part for use as an active switching element in a temperature-dependent switch, with a flexible region in which a contact surface is integrated.

The bimetallic part can be constructed in a classical manner, so it does not have to have at least one inner region and an outer region surrounding the at least one inner region, the inner and outer regions being formed in sections and in sections mechanically separated from one another and embossed in opposite directions.

In this case, it is generally preferred if either the contact surface, preferably by plating or electroplating with a conductive material, is adhesively bonded to one region, or the contact surface, preferably by rolling in of a conductive material, is positively connected to the one region.

In this way, the one area of the bimetallic part is provided with a contact area which makes it possible to electrically conduct and provide a low contact resistance to an adjacent contact area, without adversely affecting the flexibility of the bimetal part.

Further advantages will become apparent from the description and the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the respective combinations indicated, but also in other combinations or in isolation, without departing from the scope of the present invention.

Figur 1

eine schematische Ansichten eines ersten Ausführungsbeispiels eines erfindungsgemäßen Bimetallteils in Draufsicht;

Figur 2

eine schematische Ansichten eines zweiten Ausführungsbeispiels eines erfindungsgemäßen Bimetallteils in Draufsicht;

Figur 3

eine schematische Seitenansicht des Bimetallteils aus Fig. 1 in einer ersten Schaltstellung;

Figur 4

eine schematische Seitenansicht des Bimetallteils aus Fig. 1 in einer zweiten Schaltstellung;

Figur 5

in einer schematischen Schnittdarstellung ein erstes Ausführungsbeispiel eines temperaturabhängigen Schalters mit dem Bimetallteil aus Fig. 1;

Figur 6

ein zweites Ausführungsbeispiel eines temperaturabhängigen Schalters mit dem Bimetallteil aus Fig. 1;

Figur 7

ein drittes Ausführungsbeispiel eines temperaturabhängigen Schalters mit dem Bimetallteil aus Fig. 1; und

Figur 8

eine Draufsicht auf ein Bimetallteil mit integrierter Kontaktfläche.

Three embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description. Show it:

FIG. 1

a schematic view of a first embodiment of a bimetallic part according to the invention in plan view;

FIG. 2

a schematic view of a second embodiment of a bimetallic part according to the invention in plan view;

FIG. 3

a schematic side view of the bimetal from Fig. 1 in a first switching position;

FIG. 4

a schematic side view of the bimetal from Fig. 1 in a second switching position;

FIG. 5

in a schematic sectional view of a first embodiment of a temperature-dependent switch with the bimetal from Fig. 1 ;

FIG. 6

a second embodiment of a temperature-dependent switch with the bimetallic part Fig. 1 ;

FIG. 7

a third embodiment of a temperature-dependent switch with the bimetallic part Fig. 1 ; and

FIG. 8

a plan view of a bimetal with integrated contact surface.

Fig. 1 shows a schematic plan view of a bimetal 10, which is formed in the present case as a rectangular spring 11. The spring 11 is divided into an outer region 12 and an inner region 13.

The two areas 12 and 13 are partially formed integrally with each other. They are also partially separated by two longitudinally extending slots or slots 14 and 15 mechanically separated from each other so that an inner web 16 is formed, which is surrounded by two outer webs 17 and 18.

The slots or gaps 14, 15 are produced by punching, cutting or other suitable separation measures. Between two adjacent webs 16, 17; 16, 18 will thereby generate at least one such clearance, which allows these webs 16, 17, 18 to bend without mechanical interference by the respectively adjacent web 16, 17, 18. As long as this condition is met, the slots or gaps 14, 15 transverse to the longitudinal direction L can have a clear width between adjacent webs 16, 17, 18, which results from the separation method selected.

All three webs 16, 17, 18 are integrally connected to end regions 19, 20 of the sheet-metal part 11 which are opposite one another in the longitudinal direction L. In this way, the webs 17 and 18 and the end regions 19, 20 form the outer region 12, which completely surrounds the web 16, that is to say the inner region 13. The webs 16, 17, 18 can thus not shift in the longitudinal direction L against each other.

Of course, it is possible to divide the inner region 13 into a plurality of mutually parallel inner webs 16, which are mechanically separated from each other by further gaps or slots parallel to the longitudinal direction L.

At the inner web 16, an area indicated at 21, at which either according to the example of Fig. 5 a contact part is fixed non-positively or positively, according to the example of Fig. 6 a contact bridge is attached, or on which an integrated contact surface is provided, as hereinafter in connection with Fig. 8 is still discussed in detail.

In an in Fig. 2 illustrated, the second embodiment, the bimetal part 10 is formed as a disc 22 which is circular in plan view in the illustrated embodiment. However, the disc 22 may take other forms, for example, it may be made oval or elliptical.

The disc 22 also has an outer portion 12 surrounding an inner portion 13. The two regions 12, 13 are mechanically separated from each other in sections by a gap 23 of circumferentially distributed V-shaped slots, so that the inner region 13 takes the form of a serrated star. The V-shaped slots are interrupted at their tips 24, so that the inner and the outer region 13, 12 here in sections integrally merge into one another and are fixed in the radial direction R against each other.

The V-shaped slots correspond in function to the slots or gaps 14, 15 in the spring 11 Fig. 1 and have also been produced by punching, cutting or other suitable separation measures. In this way, the inner region 13 and the outer region 12 can deform without being mechanically impeded in the region of the gap 23 by the region opposite to the respective slot.

Instead of the V-shaped slots, it is also possible to provide meandering or wave-shaped slots which are interrupted in sections in order to produce the one-piece connection between the inner and outer regions.

At the inner region 13, a region 21 is again indicated, in which a contact surface is integrated, as described below with reference to FIG Fig. 8 for an otherwise conventional bimetallic disc, ie without inner and outer region is explained.

The spring 11 and the disc 22 are punched out of a sheet of bimetal, whereby they get their outer shape and possibly already in this first operation with the slots 14, 15, 23 are provided. In two further punching operations, the inner and outer regions 13, 12 are then embossed in such a way that their creep phases are suppressed, which was explained in the introduction. One of these two punching operations can also be done during the first work.

These punching operations are now carried out so that the outer and the inner region 12, 13 are shaped in opposite directions, but have the same properties. For the spring 11, this means that the inner web 16 has comparable mechanical properties, as the outer webs 17 and 18 together. In other words, in the embossing bowls or depressions are introduced, which lie on the top of the inner web 16 and the lower side of the outer webs 17 and 18, or vice versa. Depending on requirements, both inner web 16 and outer webs 17 and 18 may have embossments on the top and bottom, just just with opposite arrangement and effect.

After the punching operations, the inner and outer regions 12, 13 of the bimetal part are still in a plane when it is mechanically relaxed.

Consequently, when the bimetal part 10 is heating, the one area 12, 13 bends in one direction and the other at the same time in the other direction, when the transition temperature is exceeded. Due to the embossing and the choice of geometry while the creep phase is largely suppressed, so that the bending takes place abruptly and in opposite directions.

Due to the selected geometry, the dimensions and a corresponding choice of material as well as the embossing, the bimetal part 10 thus contains its own abutment, as it were. This results in an internal force balance, so that it is possible to set a switching point, which is maintained very accurately, since the slow phases are efficiently suppressed.

In other words, the switching between the high and the low temperature position takes place abruptly and reproducibly over many switching cycles. Furthermore, the switching hysteresis is largely suppressed.

The bimetal part 10 can therefore absorb mechanical forces and conduct electricity over long periods of time without its properties changing as a result of aging processes.

The bimetal part 10 can thus be used in the two embodiments spring 11 and disc 22 as an active switching element in a temperature-dependent switch, as discussed in detail at the beginning. The inner region 13 performs the switching function.

Because of the opposing properties of the inner and outer regions 13, 12, it is not necessary - but not excluded - that the bimetallic 10 is assigned a Federschnappteil that provides in the closed state of the switch for the contact pressure and possibly also the operating current of protective device leads.

The inner region 13 can thus directly carry a movable contact part or a contact bridge. The mechanical load and the current flow during the closing states of the switch in this novel bimetallic 10 no longer lead to the aging phenomena and switching point shifts, as they are known from the prior art.

The properties of the new bimetallic part 10 can be used particularly effectively when the disc 22 is held immovably at its outer edge 25 or the spring 11 at its in the longitudinal direction L facing away from each other end faces 26, 27 relative to the switch.

As a result, a constant length of the spring 11 in the longitudinal direction L or the disc 22 in the radial direction R forced, so that the inner and outer regions 13, 12 can snap over only simultaneously and in opposite directions. This contributes to the uniform distribution of the mechanical load and consequently to a further improved long-term stability of the switching point.

This arrangement is schematically in the side view according to 3 and 4 shown where the spring 11 off Fig. 1 with its end faces 26, 27 is held on two abutments 28, 29. In the in Fig. 3 shown low temperature position is the inner web 16 down, in the Fig. 4 shown high temperature position bent upwards. The outer webs 17, 18, of which in the 3 and 4 only the web 18 can be seen are bent opposite.

The transition between the switch positions according to 3 and 4 occurs abruptly when exceeding or falling below the switching temperature, which is determined by material, geometry and embossing.

In Fig. 5 is a schematic, sectional side view of a temperature-dependent switch 30 is shown, which is a first embodiment of the use of the bimetallic 10, which is formed in the present case as a spring 11, as an active switching element in a temperature-dependent switching mechanism.

The switch 30 comprises a pot-like lower part 31 made of conductive material, which is closed by a top 32 also conductive material. The upper part 32 is placed with the interposition of an insulating layer 33 on a shoulder 34 of the lower part 31 and secured by a flanged edge 35 fixed to the lower part 31.

The lower part 31 has a circumferential side wall 36, on which the shoulder 34 is formed.

The spring 11 is supported in the in Fig. 5 shown closed position with its end faces 26 and 27, and thus with its outer region 12, acting on an electrode 37 as an inner bottom of the lower part 31 and is fixed by the side wall 36 in the longitudinal direction L. The side wall 36 acts as an abutment in the sense of the abutment 28, 29 from 3 and 4 ,

The outer bridges, of which in Fig. 5 only the web 18 can be seen are bent downwardly, the inner web 16 is bent upward, thereby pressing a movable contact member 38 supported by it against a fixed contact part 39 which is arranged on the upper part 32. The fixed contact part 39 is designed in the manner of a rivet, whose outer resting head 41 serves as the first external connection, with which thus the inner region 13 is in electrical connection.

As the second outer terminal 42, the flanged edge 35 is used.

The spring 11, together with the movable contact part 38, a temperature-dependent switching mechanism 43, which produces or opens depending on its temperature, an electrically conductive connection between the external terminals 41 and 42.

In the in Fig. 5 shown closed position, the in Fig. 4 schematically corresponds to shown, the end faces 26, 27 via the bottom 37 in electrically conductive connection with the second outer terminal 42, while the movable contact part 38 is connected by contact with the fixed contact part 39 is electrically connected to the first outer terminal 41. For this purpose, a contact surface 44 is provided on the movable contact part 38 which, when the switch 30 is closed, comes into contact with a contact surface 45 which is provided on the fixed contact part 39.

In this way, an electrically conductive connection between the external terminals 41 and 42 is made via the spring 11.

If the temperature of the spring 11 increases beyond the response temperature addition, the spring 11 snaps without creeping abruptly from the in Fig. 5 shown configuration in its open position, which is schematically in Fig. 3 is shown. The inner web 16 thereby bends downwards and lifts the movable contact part 38 from the fixed contact part 39, whereby the circuit is opened. At the same time, the outer webs 17, 18 also snap over.

The movable contact part 38 moves together with the inner web 16 between the outer webs 17 and 18 therethrough.

Fig. 6 shows a temperature-dependent switch 50, as he from the above-mentioned DE 197 08 46 A1 is known, the disclosure of which is hereby expressly made the subject of the present application.

The switch 50 has a lower part 51 which is closed by an upper part 52. In the upper part 52, two fixed contact parts 53, 54 are arranged, which are connected to external terminals 55, 56. With the fixed contact parts 53, 54 two contact surfaces act together on a contact bridge 57, which is fastened via a rivet 58 to the inner web 16 of a bimetal part 10 designed as a spring 11 according to the invention.

The spring 11 is fixed with its end faces 26, 27 in a groove 61 of the lower part 51, which thus serves as an abutment.

The spring 11 forms here together with the contact bridge 57 and the rivet 58, a temperature-dependent switching mechanism 62, which makes or opens depending on its temperature, an electrically conductive connection between the external terminals 55 and 56.

In the in Fig. 6 shown position, the switch 50 is closed, the inner web 16 provides the contact pressure between the contact bridge 57 and the fixed contact parts 53, 54. Increases the temperature of the switch 50 and thus the spring 11, so this does not lead to a creep phase that affects the contact pressure. Only when the switching temperature is reached, the spring 11 jumps from the in Fig. 6 shown position, the position off Fig. 4 corresponds to the position according to Fig. 3 in which the inner web 16, the contact bridge 57 lifts from the fixed contact parts 53, 54 and the switch 50 opens.

The outer webs 17, 18 also snap into their high-temperature position, with the contact bridge 57 moving together with the inner web 16 between the outer webs 17 and 18.

In Fig. 7 a temperature-dependent switch 70 is shown in which the disc 22 from Fig. 2 is used as an active switching element. The disk is not traversed by the current to be switched, as in the switch 30 Fig. 5 Also, it does not produce the contact pressure as in the switch 50 Fig. 6 ,

The switch 70 has a plastic body 71, which is closed at the top and bottom by sheets 72, 73, which also serve as external connections. On the upper plate 72 is in electrically conductive connection to a spring tongue 74 which carries at its free end a movable contact member 75 which is in the illustrated low-temperature position with a fixed contact member 76 in abutment, which is arranged on the lower plate 73.

In the plastic body 71, a receiving space 78 is formed by a wall 77, in which the disc 22 is located, which rests with its edge 25 of the serving as abutment edge 77 and is fixed so in the radial direction R.

On the spring tongue 74 is a downwardly facing dome 79 can be seen on the disc 22 acts on its inner region 13 when it changes its configuration due to temperature increase and the movable contact member 75 lifts from the fixed contact part 76.

Federzuge 74, disc 22 and contact parts 75, 76 thereby form a temperature-dependent switching mechanism 80th

In the in Fig. 7 shown closed position of the switch 70 is the non-flow-through disc 22 in a configuration similar to Fig. 3 , the dome 79 protrudes into the outer region 12, from which the inner region 13 downwards is bent. When switching the inner area 13 jumps up, reaches the configuration of Fig. 4 and presses on the dome 79, the spring tongue 74 upwards.

Instead of a movable contact or a contact bridge to assemble, as in the switches from the Fig. 5 and 6 , may be provided on the bimetallic part 10, a region 21 in which a contact surface is integrated, as shown in the Fig. 1 and 2 is indicated.

Based on Fig. 8 will now be explained for an otherwise conventional bimetallic disc 81, ie without inner and outer region, as in an approximately central flexible region 21, an integrated contact surface 82 can be generated.

On the one hand, by means of plating or electroplating with a conductive material 83, a contact surface 82 connected in a materially joined manner to the region 21 can be produced.

On the other hand, the contact surface 82 can be produced by rolling in a conductive material 83, for example of gold wires, whereby the contact surface is positively connected to the region 21.

In this way, the flexible region 21 of the bimetallic disc 81 is provided with a highly electrically conductive contact surface 82, which has a low contact resistance to an adjacent contact surface, wherein the flexibility of the bimetallic part is not adversely affected.

The bimetallic disc 81 may be at the switch Fig. 5 or 6 can be used, wherein the movable contact part 38 and the contact bridge 57 are now replaced so to speak by the integrated contact surface 82.

Claims (19)

1. Bimetal part for use as an active switching element in a temperature-dependent switch (30, 50, 70), said bimetal part having at least one inner region (13) and one outer region (12) surrounding the at least one inner region (13), the inner region (13) and the outer region (12) being formed such that in certain portions they are in one piece with one another and in certain portions they are mechanically separated from one another, at least one contact area (21, 82) being provided on the inner region (13), characterized in that the inner region (13) and the outer region (12) are provided from different sides with indentations in the form of dimples and depressions such that their creeping phases are suppressed, whereby the inner and outer regions (13, 12) have the same mechanical properties.
2. Bimetal part according to Claim 1, characterized in that it is formed as an approximately rectangular spring (11).
3. Bimetal part according to Claim 2, characterized in that the spring (11) comprises as an inner region (13) at least one inner web (16) extending in the longitudinal direction (L) of the spring (11) and as an outer region (12) at least two outer webs (17, 18) extending in the longitudinal direction (L) of the spring (11), which outer webs accommodate the inner web (16) between them and are each separated from it by way of a gap (14, 15) extending in the longitudinal direction (L).
4. Bimetal part according to Claim 3, characterized in that the inner web (16) has mechanical properties comparable to those of the outer webs (17, 18) together.
5. Bimetal part according to Claim 1, characterized in that it is formed as a disc (22).
6. Bimetal part according to Claim 5, characterized in that the inner region (13) is surrounded by a gap (23) which is interrupted in certain portions (24).
7. Bimetal part according to Claim 6, characterized in that the gap (23) runs in a zigzagging, meandering or wavy manner.
8. Bimetal part according to anyone of Claims 5 to 7, characterized in that the inner region (13) has mechanical properties comparable to those of the outer region (12).
9. Bimetal part according to anyone of Claims 1 to 8, characterized in that the inner region (13) bears a contact bridge (57) with two contact areas.
10. Bimetal part according to anyone of Claims 1 to 8, characterized in that the inner region (13) bears a movable contact part (38), which is preferably fixed in an interlocking or non-positively engaging manner, and on which the at least one contact area (45) is formed.
11. Bimetal part according to anyone of Claims 1 to 8, characterized in that the contact area (82) is integrated in the inner region (13).
12. Bimetal part according to Claim 11, characterized in that the contact area (82) is connected to said inner region (13) in a materially bonded manner, preferably by plating or electrocoating with a conductive material (83).
13. Bimetal part according to Claim 11, characterized in that the contact area (82) is connected to said region (13) in an interlocking manner, preferably by incorporating a conductive material (83) by rolling.
14. Temperature-dependent switch with two external connections (41, 42; 55, 56; 72, 73) and a temperature-dependent switching mechanism (43, 62, 80) which, depending on its temperature, closes or opens an electrically conducting connection between the two external connections (41, 42; 55, 56; 72, 73), the bimetal part (10) according to anyone of Claims 1 to 13 being provided as an active switching element in the switching mechanism (43, 62, 80).
15. Temperature-dependent switch according to Claim 14, characterized in that the bimetal part (10) is in connection by way of its inner or outer region (13, 12) with one (42) of the two external connections (41, 42), and at its outer and inner region (12, 13), respectively, interacts, preferably by way of a movable contact part (38), with a fixed contact part (39), which is in connection with the other external connection (41).
16. Temperature-dependent switch according to Claim 14, characterized in that the bimetal part (10) bears on its inner region (13) a contact bridge (57), which interacts with two fixed contact parts (53, 54) that are each in connection with one of the external connections (55, 56).
17. Temperature-dependent switch according to Claim 14, characterized in that the switching mechanism (80) comprises a spring tongue (74), which at its fixed end is in connection with one (72) of the two external connections (72, 73), and at its free end bears a movable contact part (75), which interacts with a fixed contact part (76) which is in connection with the other external connection (73), the bimetal part (10) interacting with the spring tongue (74) in such a way that the movable contact part (75) is lifted from the fixed contact part (76) when a switching temperature is reached.
18. Temperature-dependent switch according to anyone of Claims 14 to 17, characterized in that the bimetal part (10) is formed as an approximately rectangular spring (11), which is mounted at both its end faces (26, 27) immovably with respect to the switch.
19. Temperature-dependent switch according to anyone of Claims 14 to 17, characterized in that the bimetal part (10) is formed as a disc (22), which is mounted at its periphery (25) immovably with respect to the switch.

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