EP4369374A2 - Temperature-dependent switch - Google Patents

Abstract

Temperature-dependent switch (10) with a housing (12) which has a cover part (16) with an upper side (24) and a lower part (14) with a raised, circumferential wall (28), the upper section (30) of which is bent over onto the upper side (24) of the cover part (16) and thereby holds the cover part (16) to the lower part (14), two contact surfaces (48, 50) being provided on the outside of the housing (12) and a switching mechanism (34) being arranged in the housing (12), which is designed to switch, depending on its temperature, between a closed state in which the switching mechanism (34) establishes an electrically conductive connection between the two contact surfaces, and an open state in which the switching mechanism (34) opens the electrically conductive connection between the two contact surfaces (48, 50). A sealing ring (32) is arranged on the upper side (24) of the cover part (16), which is in sealing contact with the bent upper section (30) of the wall.

Description

The present invention relates to a temperature-dependent switch with a housing that has a cover part with an upper side and a lower part with a raised, circumferential wall, the upper section of which is bent over onto the upper side of the cover part and thereby holds the cover part to the lower part, wherein two contact surfaces are provided on the outside of the housing and a switching mechanism is arranged in the housing, which is designed to switch, depending on its temperature, between a closed state in which the switching mechanism establishes an electrically conductive connection between the two contact surfaces, and an open state in which the switching mechanism opens the electrically conductive connection between the two contact surfaces, wherein a sealing ring is arranged on the upper side of the cover part, which is in sealing contact with the bent over, upper section of the wall.

A temperature-dependent switch according to the preamble of claim 1 is known from FR 2 114 918 A5 Other examples of temperature-dependent switches are known from the DE 196 23 570 A1 and the EN 10 2011 104 984 A1 known.

Such temperature-dependent switches are used in a known manner to monitor the temperature of a device. To do this, the switch is brought into thermal contact with the device to be protected via one of its outer surfaces, for example, so that the temperature of the device to be protected influences the temperature of the switching mechanism.

The switch is electrically connected in series to the supply circuit of the device to be protected via connecting cables that are attached to its external contact surfaces in a material-locking manner (e.g. by soldering or welding), so that below the response temperature of the switch, the supply current of the device to be protected flows through the switch.

The one from the DE 196 23 570 A1 The known switch has a deep-drawn base part in which an inner circumferential shoulder is provided on which a cover part rests. The cover part is held firmly on this shoulder by a raised and flanged edge of the base part.

In the switch known from this publication, the cover part and the base part are made of electrically conductive material. Therefore, an insulating film is provided between them, which extends parallel to the cover and is pulled upwards at the side so that its edge area extends to the top of the cover part. In this switch, the flanged edge, i.e. the bent, upper section of the wall of the base part, presses against the cover part with the insulating film in between. The insulating film therefore serves to electrically insulate the two electrically conductive housing parts of the switch.

The one from the DE 196 23 570 A1 Known switches also include a temperature-dependent switching mechanism, which has a spring snap disk that carries a movable contact part, as well as a bimetal disk that is placed over the movable contact part. The spring snap disk presses the movable contact part against a stationary counter-contact that is arranged on the inside of the cover part.

The edge of the spring snap-action disc rests against the lower part of the housing, so that the electrical current flows from the lower part through the spring snap-action disc and the movable contact part into the stationary counter-contact and from there into the cover part.

The first external connection is a contact surface that is arranged centrally on the cover part. The second external connection is a contact surface provided on the flanged edge of the base part. However, it is also possible to arrange the second external connection not on the edge, but on the side of the current-carrying housing or on the underside of the base part.

From the DE 198 27 113 C2 It is also known to attach a so-called contact bridge to the spring snap disk, which is pressed by the spring snap disk against two stationary counter contacts provided on the cover part. In this case, both contacts of the switch to which the external connections are attached are arranged on the cover part. The two contacts are electrically insulated from one another. In such a design variant of the switch, the cover part is therefore preferably made of an insulating material or a PTC thermistor. Such PTC thermistors are also referred to as PTC resistors. They are made, for example, from semiconducting, polycrystalline ceramics such as barium titanate (BaTiO ₃ ).

In the DE 198 27 113 C2 In the known switch, the current flows from one stationary contact through the contact bridge into the other stationary contact, which is also arranged on the cover part, so that the spring snap disk itself is not flowed through by the operating current. The contact bridge is therefore often also generally referred to as a current transfer element.

This design is chosen in particular when very high currents have to be switched, which can no longer be easily conducted via the spring washer itself.

In the two design variants mentioned above, a bimetallic disk is provided for the temperature-dependent switching function, which lies in the switching mechanism without any force below its transition temperature, whereby it is arranged geometrically between the movable contact part or the contact bridge and the spring snap disk.

In the context of the present invention, a bimetal part is understood to be a multi-layer, active, sheet-metal component made of two, three or four inseparably connected components with different thermal expansion coefficients. The connection of the individual layers of metals or metal alloys is material-locking or form-locking and is achieved, for example, by rolling.

Such bimetal parts have a first stable geometric conformation in their low-temperature position and a second stable geometric conformation in their high-temperature position, between which they switch depending on the temperature in a hysteresis manner. When the temperature changes above their response temperature or below their recovery temperature, the bimetal parts snap into the other conformation. The bimetal parts are therefore often referred to as snap disks, and when viewed from above they can have an elongated, oval or circular shape.

If the temperature of the bimetal disc rises above the jump temperature as a result of a temperature increase in the device to be protected, the bimetal disc changes its configuration and works against the spring snap disc in such a way that it lifts the movable contact part from the stationary contact or the contact bridge/current transfer element from the two stationary counter contacts, so that the switch opens and the device to be protected is switched off and cannot heat up any further.

In the above-mentioned designs of the temperature-dependent switch, the bimetal disc is mechanically supported without force below its transition temperature, whereby the bimetal disc is also not used to conduct the current.

This has the advantage that the bimetal disc has a long service life and that the switching point, i.e. the transition temperature of the bimetal disc, does not change even after many switching cycles.

If lower demands are placed on the mechanical reliability or the stability of the transition temperature, the bimetal snap disc can also take over the function of the spring snap disc and possibly even the current transmission element, so that the switching mechanism only comprises one bimetal disc, which then carries the movable contact part or has two contact surfaces instead of the current transmission element, so that the bimetal disc not only ensures the closing pressure of the switch, but also carries the current when the switch is closed.

It is also known to provide such switches with a parallel resistor that is connected in parallel to the external connections. This parallel resistor takes over part of the operating current when the switch is open and keeps the switch at a temperature above the transition temperature so that the switch does not automatically close again after cooling down. Switches of this type are called self-holding.

It is also known to equip such switches with a series resistor through which the operating current flows through the switch. In this way, an ohmic heat is generated in the series resistor that is proportional to the square of the current flowing. If the current exceeds a permissible level, the heat of the series resistor causes the switching mechanism to open.

In this way, a device to be protected is disconnected from its supply circuit as soon as an excessive current flow occurs, which has not yet led to excessive heating of the device.

All these different design variants can be realized with the switch according to the invention.

Instead of a usually round bimetallic disc, a bimetallic spring clamped on one side can also be used, which carries a movable contact part or a contact bridge or a current transmission element.

However, temperature-dependent switches can also be used which do not have a contact plate as the current transfer element, but rather a spring part which carries the two counter contacts or on which both counter contacts are formed. The spring part can be a bimetal part, in particular a bimetal snap disk, which not only provides the temperature-dependent switching function, but also provides the contact pressure and carries the current when the switch is closed.

From the DE 195 17 310 A1 is a to the one mentioned at the beginning DE 196 23 570 A1 A similarly constructed temperature-dependent switch is known, in which the cover part is made of a PTC thermistor material and can rest on an inner circumferential shoulder of the lower part without the interposition of an insulating film, onto which it is pressed by the flanged edge of the lower part.

In this way, the PTC thermistor cover is electrically connected in parallel to the two external terminals, giving the switch a self-holding function. This is also the case with the above-mentioned DE 198 27 113 C2 This is the case with the well-known temperature-dependent switch with contact bridge.

In the known switches, the external contact surfaces and the electrically conductive parts of the housing must still be electrically insulated after the connecting cables have been attached.

As insulation and pressure protection, the known switches are therefore often used in housings or protective caps, which serve to provide mechanical and/or electrical protection and often also protect the housing from the ingress of contamination. Examples of this can be found in the DE 91 02 941 U1 , dem DE 92 14 543 U1 , the DE 37 33 693 A1 and the DE 197 54 158 A1 .

Furthermore, the DE 41 43 671 A1 known to overmold the external connections with a one-component thermoset. EN 10 2009 039 948 It is known to cast connection lugs with an epoxy resin.

However, the use of enclosures or connection caps is often considered to be too complex in terms of construction and unsatisfactory with regard to the thermal connection to the protective device.

Therefore, the known switches are often coated with an impregnating varnish or protective varnish after the connecting cables have been soldered on. The switches are sometimes also provided with so-called resin covers, which, however, significantly increases the height of the switch. In addition, it is often not possible to ensure that the resin flows completely. There is also a risk that the resin will penetrate into open gaps and then get into the interior of the switch.

In switches where the cover is pressed onto the base with an insulating film in between, a problem with the switch not being tight is often caused by the insulating film curling or folding when it is bent over onto the top of the cover. This causes a kind of wrinkle in the insulating film, which means that the wall of the base cannot be bent over far enough onto the top of the cover. Furthermore, this waviness of the insulating film on the top and on the peripheral front side of the cover creates creepage paths for liquids, so that when the switch is impregnated with protective varnish, these can creep into the interior of the switch.

Even compared to other electrical insulation materials, the flanged edge of the lower part does not seal the upper side well enough to ensure that no liquid can get into the interior of the switch when it hardens. This is particularly problematic because such creepage paths are hardly visible from the outside and can therefore hardly be detected by a visual inspection alone.

Even when soldering connecting cables onto the top or the contact surface provided there, it cannot be completely ruled out that solder or corresponding liquids will get into the interior of the switch.

In the above-mentioned DE 196 23 570 A1 An attempt is made to reduce this problem by means of a circumferential bead which runs radially on the outside of the underside of the cover part and presses on the insulating film arranged between the lower part and the cover part.

In the EN 10 2015 114 248 A1 It is also proposed to provide a circumferential cutting burr on the shoulder of the lower part, which cuts into the insulating film. Although this solution has proven to be quite advantageous with regard to the mechanical sealing of the switch, it nevertheless has disadvantages. In particular If the housing components are stored and processed as bulk goods, these punching burrs can be damaged or ground off, meaning that the seal is not sufficiently ensured. Such damage to the punching burrs is also difficult to see with the naked eye, so that potential problem areas are usually not noticed during a visual inspection.

The previously mentioned problem of flowering or rosette formation of the insulating foil when bending the upper section of the cover part is solved according to the EN 10 2013 102 089 A1 attempts to solve this problem by cutting the edge of the insulating film into a V shape from the outside, which greatly reduces the waviness. This has also led to an improved seal on the switch.

Nevertheless, there is still a need to improve the mechanical tightness of such a temperature-dependent switch, since all of the above-mentioned solutions have led to at least minor disadvantages in practice.

It is therefore an object of the present invention to improve the mechanical sealing of the switch in a structurally simple and inexpensive manner.

• (ii) ein radial innerer Rand des Abdichtrings einen kleineren Abstand von einer zentralen Mittelachse des Schalters hat als der Befestigungsbereich, wobei der Abdichtring mit seinem radial äußeren Rand an einer Außenseite des oberen Abschnitts der Wand anliegt, die der zentralen Mittelachse des Schalters zugewandt ist, oder
• (iii) ein radial innerer Rand des Abdichtrings einen gleich großen oder größeren Abstand von einer zentralen Mittelachse des Schalters hat als der Befestigungsbereich, wobei der Abdichtring an einer Innenseite des oberen Abschnitts der Wand anliegt, die von der zentralen Mittelachse des Schalters abgewandt ist.

This object is achieved according to the invention starting from the switch of the type mentioned at the beginning in that the upper section of the wall in a fastening area presses directly or indirectly with the interposition of an insulating film on the upper side of the cover part, whereby

• (ii) a radially inner edge of the sealing ring is at a smaller distance from a central axis of the switch than the fastening region, the sealing ring resting with its radially outer edge on an outer side of the upper portion of the wall facing the central axis of the switch, or
• (iii) a radially inner edge of the sealing ring is at an equal or greater distance from a central axis of the switch than the mounting area, the sealing ring being secured to an inner side of the upper portion the wall facing away from the central axis of the switch.

During manufacture, preferably before the upper section of the raised, circumferential wall of the lower part is bent or flanged, a sealing ring is arranged on the upper side of the cover part, which sealing ring is in sealing contact with this upper wall section after it has been bent or flanged.

It has been shown that a sealing ring arranged at the mentioned location improves the mechanical sealing of the switch interior many times over.

Since, in contrast to many previously known solutions, no insulating film is used to mechanically seal the inside of the switch, but rather the additional sealing ring mentioned, the middle of the cover part can remain free for the connecting cables to be attached to it. This means that the semi-finished switch is already completely sealed before the connection technology is attached to the switch. This has the immense advantage that, for example, when soldering the connecting cables to the contact surface(s) provided in the middle of the cover part, no solder or soldering flux can penetrate into the inside of the switch. A final manual sealing of the switch is no longer necessary.

If the switch is provided with an impregnating varnish or protective varnish after the connecting cables have been attached in order to electrically insulate them, the sealing ring provided according to the invention also guarantees an extremely good mechanical seal which prevents such varnishes or resins from penetrating into the interior of the switch.

The solution according to the invention also has immense advantages from a production point of view. The individual components of the housing do not have to be provided with punching burrs or a bead to ensure mechanical sealing. The sealing ring simply has to be arranged on the top of the cover part, preferably before the upper section of the wall is flanged. This can be done fully automatically.

The increased tightness achieved with the sealing ring and the associated greater flexibility during production far outweigh the costs of the additional sealing ring.

The sealing ring is typically a very cost-effective component that can be easily stored and handled in automated production.

According to a first alternative of the present invention, it is provided that the upper section of the wall in a fastening area presses directly or indirectly onto the top of the cover part with an insulating film in between, and a radially inner edge of the sealing ring is at a smaller distance from a central center axis of the switch than the fastening area, with the sealing ring resting with its radially outer edge on an outside of the upper section of the wall that faces the central center axis of the switch. The upper wall section can therefore also be flanged directly onto the top of the cover part or press onto an insulating film that is arranged between the flanged edge and the cover part.

In this case, the fastening area is understood to be the contact area in which the bent or flanged upper section of the wall touches the upper side of the cover part directly or indirectly with the interposition of an insulating film.

In this case, the sealing ring is arranged radially further inward than the flanged edge. The sealing ring can also be attached to the cover part, for example, after the upper edge section of the wall has been flanged. It then preferably rests with its radially outer edge on the outside of the flanged edge of the wall and can be glued, hot-stamped or welded to the top of the cover part and/or the flanged, upper section of the wall using a weld connection produced by means of ultrasonic welding.

According to a second alternative of the present invention, it is provided that the upper section of the wall in a fastening area presses directly or indirectly onto the upper side of the cover part with the interposition of an insulating film and a radially inner edge of the sealing ring has an equal or greater distance from the central axis of the switch than the fastening area, wherein the sealing ring rests against an inner side of the upper section of the wall which faces away from the central axis of the switch.

According to this alternative, the upper wall section is therefore flanged over the sealing ring so that the sealing ring is located radially further out than the fastening area mentioned, in which the upper, bent or flanged section of the wall presses directly or indirectly on the top of the cover part. The flanged edge functions as a kind of circular tunnel in which the sealing ring is arranged.

It should be expressly mentioned at this point that in addition to the sealing ring according to the invention, an insulating film can also be used in the switch according to the invention. This is particularly preferred when both the cover part and the lower part of the housing are made of an electrically conductive material and the two housing parts have to be electrically insulated. In such a case, however, the insulating film mainly takes on the function of electrically insulating the two housing parts, since the mechanical seal, as already mentioned above, is achieved according to the invention via the sealing ring, which is in sealing contact with the bent, upper section of the wall.

If an insulating film is used for electrical insulation of the two housing parts, it is preferred that the sealing point at which the sealing ring is arranged is free of the insulating film.

According to one embodiment of the present invention, the sealing ring is integrally connected to the top of the cover part and/or the bent, upper section of the wall. Preferably, the sealing ring is connected to both the top of the The cover part and the bent upper section of the raised wall of the lower part are firmly bonded together.

This material-locking connection further improves the sealing effect achieved by the sealing ring. In terms of production technology, such a material-locking connection can be produced very easily and inexpensively.

Preferably, the sealing ring is glued, hot-stamped or welded to the upper side of the cover part and/or the bent upper section of the wall by means of a welded joint produced by means of ultrasonic welding.

Welding the sealing ring using ultrasonic welding has proven to be particularly advantageous. Ultrasonic welding allows a clean and lasting connection of the sealing ring to the top of the cover part and/or the bent edge of the upper section of the wall of the base part. The sealing effect is thus improved many times over at the connection points mentioned.

Another advantage is that the welding process using ultrasonic welding, for example in comparison to gluing the above-mentioned components, can also be carried out after the sealing ring has been mounted on the top of the cover part and the upper section of the wall of the base part has been bent or flanged. This simplifies the production-technical handling many times over.

Due to the comparatively low heat development during ultrasonic welding, temperature-related damage inside the switch, especially to the sensitive switching mechanism, can be effectively avoided. This also applies if the housing of the switch is made largely of metal. Despite the very good heat conduction properties of the metal, the comparatively low heat development that occurs during ultrasonic welding does not lead to the stationary contact, which is typically arranged on the cover part of the housing, coming loose undesirably. There is also no danger of the stationary contact and the movable contact part of the switchgear are welded together during the ultrasonic welding process. The risk of the snap domes being damaged by the ultrasonic welding process is also reduced to a minimum.

Another advantage is that no welding filler materials are required for ultrasonic welding. This means that compact weld seams can be created. In addition, the impact on the environment is significantly reduced, as the use of environmentally harmful materials can be completely avoided.

In ultrasonic welding, the components to be joined are welded using a high-frequency mechanical vibration. The vibration generated leads to heating between the components to be joined due to molecular and interfacial friction. Accordingly, ultrasonic welding is also suitable for joining a metal component to a plastic component, as is the case here with the switch housing and the sealing ring.

In ultrasonic welding tools, a generator produces electronic vibrations that are converted into mechanical vibrations by an ultrasonic converter. These are fed to the components to be joined via a so-called sonotrode. In a fraction of a second, the ultrasonic vibrations generated in this way produce frictional heat on the joining surfaces of the components to be joined, which melts the material and bonds the components together.

The parameters to be set during ultrasonic welding, such as amplitude and frequency, can be adapted to suit the circumstances. The parameters to be set and their respective values are known to the specialist and can be found in the relevant standards.

According to a further preferred embodiment of the present invention, the sealing ring is designed as a circular plastic ring.

The cross-section of the sealing ring can be chosen as desired, e.g. circular (O-ring), triangular (delta ring), rectangular, square (quad ring) or oval. More complex cross-sectional shapes are also conceivable. The sealing ring can also be a standard flat gasket.

All common sealing materials, such as fluoroplastics, polyaryletherketones, polyamides, polyacetals or polyethylenes, can be considered as materials for the sealing ring.

According to a further embodiment, it is provided that the upper section of the wall is bent by at least 90°, preferably by at least 120°, when viewed in a cross-section.

The upper section of the wall can also be bent or curved by approximately 180°, so that a circumferential bead is formed which is, for example, U-shaped in cross section. However, it is preferred according to the invention if the upper section of the circumferential wall is bent inwards by at least 120°, because then the front side of the bent wall section comes into contact from above with the top of the cover part or with the insulating film arranged on it, so that the cover part is held sufficiently well on the lower part of the housing.

As already mentioned at the beginning, it can be provided in one embodiment that the lower part and the cover part are each made of electrically conductive material and an insulating film is arranged between the cover part and the lower part.

In this case, it is preferred that a first of the two contact surfaces is arranged on the cover part and a second of the two contact surfaces is arranged on the lower part, and that the switching mechanism carries a movable contact part which interacts with a stationary counter-contact which is arranged on an inner side of the cover part and interacts with the first of the two contact surfaces. This then corresponds, for example, to a basic switch structure as shown in the EN 10 2013 102 089 A1 is known.

According to a further embodiment of the switch according to the invention, it is provided that the lower part is made of electrically conductive material and the cover part is made of insulating material or PTC material.

In this case, the two contact surfaces can be arranged on the cover part and the switching mechanism can carry a current transmission element that interacts with two stationary counter-contacts that are arranged on an inner side of the cover part and each interact with one of the two contact surfaces. Such a basic switch structure corresponds, for example, to the structure as shown in the DE 198 27 113 C2 is known.

Regardless of the type of construction of the switch housing and the switching mechanism, it is preferred in the switch according to the invention that the switching mechanism has a bimetal part which carries a movable contact part and thus conducts the current through the switch.

The bimetal part can be a round, preferably circular bimetal snap disk, although it is also possible to use an elongated bimetal spring clamped on one side as the bimetal part.

However, it is preferred if the switching mechanism also has a spring snap disk, which then carries the movable contact part and conducts the current through the closed switch and ensures the contact pressure when closed. In this way, the bimetal part is relieved of both the current conduction and the mechanical load when closed, which increases the service life of the switch and ensures that the switching temperature remains stable over the long term.

The present invention is particularly suitable for round temperature-dependent switches, which are therefore round, circular or oval when viewed from above onto the lower part, although other housing shapes can also be used according to the invention.

Further features and advantages can be found in the description and the attached drawings.

It is understood that the features mentioned above and those to be explained below can be used not only in the combination specified in each case, but also in other combinations or on their own, without departing from the scope of the present invention.

Fig. 1

eine schematische Schnittansicht eines beispielhaften temperaturabhängigen Schalters, der für das Verständnis der vorliegenden Erfindung hilfreich ist;

Fig. 2

eine schematische Schnittansicht eines weiteren beispielhaften temperaturabhängigen Schalters, der für das Verständnis der vorliegenden Erfindung hilfreich ist;

Fig. 3

eine schematische Schnittansicht eines ersten Ausführungsbeispiels des erfindungsgemäßen temperaturabhängigen Schalters;

Fig. 4

eine schematische Schnittansicht eines zweiten Ausführungsbeispiels des erfindungsgemäßen temperaturabhängigen Schalters; und

Fig. 5

eine schematische Schnittansicht eines weiteren beispielhaften temperaturabhängigen Schalters, der für das Verständnis der vorliegenden Erfindung hilfreich ist.

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. They show:

Fig.1

a schematic sectional view of an exemplary temperature dependent switch useful in understanding the present invention;

Fig. 2

a schematic sectional view of another exemplary temperature dependent switch useful in understanding the present invention;

Fig.3

a schematic sectional view of a first embodiment of the temperature-dependent switch according to the invention;

Fig.4

a schematic sectional view of a second embodiment of the temperature-dependent switch according to the invention; and

Fig.5

a schematic sectional view of another exemplary temperature dependent switch helpful in understanding the present invention.

In Fig.1 is shown schematically, not to scale and in lateral section, a temperature-dependent switch 10 which has a housing 12 which has an electrically conductive, pot-like lower part 14 and an electrically conductive, plate-like cover part 16.

In the lower part 14, which is circular in plan view, an inner circumferential shoulder 18 is provided, on which the cover part 16 rests with an insulating film 20 in between, which closes the lower part 14.

The cover part 16 has a circumferential end face 22 which separates an upper side 24 from an inner side 26. The insulating film 20 extends along the inner side 26 and along the end face 22 and reaches with its upper edge to the upper side 24.

The lower part 14 has a cylindrical, raised wall 28, the upper section 30 of which is bent or flanged onto the upper side 24 of the cover part 16. In this way, the cover part 16 is held to the lower part 14 with the insulating film 20 in between.

The insulating film 20 ensures electrical insulation of the cover part 16 from the lower part 14. The insulating film 20 also provides a mechanical seal that prevents liquids or contaminants from entering the housing interior from the outside. However, for additional mechanical sealing, according to the invention a sealing ring 32 is also provided, which is in sealing contact with the bent upper section 30 of the wall 28. This sealing ring 32 is arranged on the upper side 24 of the cover part 16.

In the Fig.1 In the switch shown as an example, the sealing ring 32 is clamped between the upper section 30 of the wall 28 and the top side 24 of the cover part 16. During the manufacture of the temperature-dependent switch 10, the sealing ring 32 is preferably placed on the top side 24 of the cover part 16 before the upper section 30 of the wall 28 is bent or flanged inwards. By bending or flanged the upper section 30 of the wall 28, the sealing ring 32 is then clamped between the wall 28 and the cover part 16. The production steps mentioned can be fully automated.

The sealing ring 32 can also be glued to the cover part 16. The sealing ring 32 can also be glued to the bent, upper section 30 of the wall 28. This bonding can also be done fully automatically, for example by applying a suitable adhesive to the top and bottom of the sealing ring 32 before it is arranged on the cover part 16 and clamped between the cover part 16 and the bent, upper section 30 of the wall 28.

However, not only for reasons of improving the sealing effect of the sealing ring 32, but also from a production-technical point of view, it is preferred to create a material-locking connection between the sealing ring 32, the upper side 24 of the cover part 16 and/or the bent, upper section 30 of the wall 28 by means of a welded connection produced by means of ultrasonic welding. This welded connection produced by means of ultrasonic welding can also be created after the upper section 30 of the wall 28 has already been bent or flanged and the sealing ring 32 has been clamped underneath.

Alternatively, a material-locking connection between the aforementioned components 32, 16, 30 can also be created by means of hot stamping.

However, depending on the clamping force created by the bent or flanged upper section 30 of the wall 28, it may also be sufficient to simply place the sealing ring 32 on the cover part 16 and clamp it between the upper section 30 and the top side 24.

The sealing ring 32 is an O-ring made of plastic. In general, other circular plastic rings can also be used in the same or a similar way, for example with a triangular, rectangular, square, oval or complex-shaped cross-section.

In the housing 12 of the switch 10 formed by the lower part 14 and the cover part 16, a temperature-dependent switching mechanism 34 is arranged, which has a spring snap disk 36, which centrally carries a movable contact part 38 on which a freely inserted bimetallic snap disk 40 sits.

The spring snap disk 36 is supported on a base 42 on the inside of the lower part 14, while the movable contact part 38 is in contact with a stationary counter-contact 46, which is arranged on the inner side 26 of the cover part 16, through a central opening 44 in the insulating film 20.

The external connection of the switch 10 is made of Fig.1 two contact surfaces 48, 50. A first contact surface 48 is formed in a central region of the upper side 24 of the cover part 16. A second contact surface 50 is formed on the bent upper section 30 of the wall 28. However, a contact surface that is formed on the peripheral, surrounding housing outer wall 52 or on the underside 54 of the lower part 14 can also serve as the second contact surface 50.

The underside 54 of the lower part 14 is preferably flat. The switch 10 can be thermally coupled to a device to be protected via this underside 54.

In this way, the temperature-dependent switching mechanism 34 in the Fig.1 shown low temperature position, an electrically conductive connection is established between the two outer contact surfaces 48, 50, wherein the operating current flows via the stationary counter contact 46, the movable contact part 38, the spring snap disk 36 and the lower part 14.

Increases at switch 10 from Fig.1 If the temperature of the bimetal snap-action disk 40 rises above its response temperature via the thermal contact of the bottom 54 to the device to be protected, it snaps open from the Fig.1 shown convex position into its concave position in which it lifts the movable contact part 38 against the force of the spring snap disk 36 from the stationary contact 46 and thus opens the circuit.

In Fig. 2 another exemplary switch 10 is shown, wherein the same reference numerals as before have been used for identical components and design features.

In contrast to the Fig.1 In the switch shown, the upper section 30 of the wall 28 penetrates at least partially into the sealing ring 32. Preferably, the upper section 30 of the wall 28 penetrates with its free, front edge 56 along the entire outer circumference, all the way around, into the sealing ring 32. Particularly preferably, a penetration depth is at least 10% of the diameter of the sealing ring 32.

In the Fig. 2 In the switch shown, the upper section 30 of the wall 28 penetrates the sealing ring 32 from the outside. However, it is also quite possible that the upper section 30 of the wall 28 penetrates the sealing ring 32 from above. For this, the upper section 30 of the wall 28 would only have to be flanged a little further than is the case in Fig. 2 shown, for example by a total of 180°.

By penetrating the peripheral edge 56 of the wall 28 into the sealing ring 32, the sealing effect of the sealing ring 32 can be further improved since an additional mechanical barrier is created.

The sealing ring 32 is inserted into the Fig. 2 shown embodiment is still pressed onto the upper side 24 of the cover part 16 by the bent or flanged upper section 30 of the wall 28. In this way, the sealing ring 32 also seals the interface between the underside of the sealing ring 32 and the upper side 24 of the cover part 16.

Even with an arrangement of the sealing ring 32 as shown in Fig. 2 As shown, it is preferred that the sealing ring 32 is integrally connected to the upper side 24 of the cover part 16 and/or the upper section 30 of the wall 28. As already mentioned above, this can be done by gluing, hot stamping or welding the above-mentioned components by means of ultrasound.

Fig.3 shows a first embodiment of the switch 10 according to the invention. In this embodiment, the upper section 30 of the wall 28 is flanged by 180° or at least approximately 180°, so that in cross section it essentially corresponds to the shape of an upside-down U. The front edge 56 of the flanged, upper section 30 of the wall 28 presses vertically or approximately vertically with the insulating film 20 in between onto the upper side 24 of the cover part 16.

The area in which the edge 56 presses onto the cover part 16 from above with the insulating film 20 in between is referred to here as the fastening area 58. This fastening area 58 is a circular line running all the way around or a circular ring area running all the way around, to which the mechanical pressure is transferred from the wall 28 of the lower part 14 to the cover part 16.

In order to prevent a short circuit between the lower part 14 and the cover part 16 in this area, the insulating film 20 according to this embodiment is pulled slightly further upwards and folded over onto the upper side 24 of the cover part 16.

If the lower part 14 or the cover part 16 is made of an insulating material, the flanged upper section 30 of the wall 28 with its edge 56 can also press directly (without the intermediate layer of the insulating film 20) onto the upper side 24 of the cover part 16.

It is also understood that the insulating film 20 can also be continued further, under the sealing ring 32, if the lower part 14 and the cover part 16 are made of an electrically conductive material.

In the Fig.3 In the embodiment shown, the sealing ring 32 is placed from the radial inside on the upper, flanged section 30 of the wall 28. A radially inner edge 62 of the sealing ring 32 is therefore at a smaller distance from the central axis 60 of the switch 10 than the fastening area 58.

On the opposite side, the sealing ring 32 is applied with its radially outer edge or edge region 64 to an outer side 66 of the flanged, upper section 30 of the wall 28, which, as can be seen from Fig.3 can be seen, faces the central axis 60 of the switch 10.

Here too, the sealing ring 32 is preferably integrally connected to the outside 66 of the flanged, upper section 30 of the wall 28 in order to improve its sealing effect. Likewise, the sealing ring 32 is also preferably integrally connected to the top 24 of the cover part 16. The integral connection of the sealing ring 32 to the outside 66 of the wall 28 and the top 24 of the cover part 16 creates several mechanical barriers that prevent contaminants from penetrating the interior of the switch. In order to get into the interior of the switch, contaminants would first have to get past the sealing ring 32 and into the fastening area 58, which is almost impossible due to the integral connection between the sealing ring 32 and the outside 66 and the top 24. In addition, a further mechanical barrier is provided in the fastening area 58, since the edge 56 of the flanged, upper section 30 of the wall 28 presses onto the insulating film 20 or even partially penetrates it. The same applies if the edge 56 presses directly onto the upper side 24 of the cover part 16 (without the insulating film 20 in between).

In the Fig.4 In the second embodiment shown, the upper portion 30 of the wall 28 is beaded into an inverted U in the same or at least similar manner as in the Fig.3 shown, second embodiment. In contrast, the sealing ring 32 is now arranged radially further outward and rests from the inside on an inner side 68, which faces away from the central axis 60 and is opposite the outer side 66, on the flanged, upper section 30 of the wall 28.

The sealing ring 32 rests here with its radially inner edge 62 on the inner side 68 of the flanged, upper section 30 of the wall 28. Accordingly, the radially inner edge 62 of the sealing ring 32 has a greater distance from the central axis 60 of the switch 10 than the fastening area 58 in which the edge 56 of the flanged, upper section 30 of the wall 28 with the insulating film 20 in between onto the cover part 16.

In this embodiment, the sealing ring 32 is preferably also materially connected to the inner side 68 of the flanged, upper section 30 of the wall 28. Likewise, the sealing ring 32 is also preferably materially connected to the upper side 24 of the cover part, either directly or indirectly with the insulating film 20 in between.

It is also possible in this embodiment for the flanged upper section 30 of the wall 28 to press with its edge 56 directly onto the upper side 24 of the cover part 16, provided that no electrical insulation is necessary between the lower part 14 and the cover part 16. In such a case, it is preferred that the sealing ring 32 also rests directly on the upper side 24 of the cover part 16 and is integrally connected thereto.

Fig.5 shows another exemplary switch 10. The arrangement of the sealing ring 32 is the same or at least similar to the arrangement of the sealing ring 32 as described above with respect to the Fig.1 shown, first embodiment. The sealing ring 32 is clamped between the bent upper section 30 of the wall 28 and the upper side 24 of the cover part 16.

The Fig.5 However, the switch shown differs from the one in Fig. 1 to 4 shown switches in the type of construction of the switching mechanism 34 and the housing 12. For the sake of simplicity, the previously used reference numerals for identical or equivalent components have also been Fig.5 used.

The housing 12 here comprises a pot-shaped lower part 14 made of electrically conductive material. The cover part 16 of the housing 12 is in the Fig.5 However, the switches shown are made of insulating material or PTC material. Insulation using an insulating foil, as used in the switches according to Fig. 1 to 4 is used, is therefore not necessary here.

Between the cover part 16 and the lower part 14, a spacer ring 74 is provided which keeps the cover part 16 spaced from the lower part 14.

Two stationary counter contacts 46, 47 are provided on the cover part 16. The counter contacts 46 and 47 are designed as rivets that extend through the cover part 16 and end externally in the heads 48, 50, which serve as contact surfaces for the external connection of the switch 10.

The switching mechanism 34 comprises a current transmission element 70 as a contact element, which is designed as a contact plate or contact bridge, the upper side 76 of which is coated in an electrically conductive manner, so that the current transmission element 70 in the Fig.5 shown, closed position of the switch 10 rests against the mating contacts 46, 47 and ensures an electrically conductive connection between the two mating contacts 46, 47.

The current transmission element 70 is connected to a bistable spring snap disk 36 and a bistable bimetal snap disk 40 via a rivet 72, which is also to be regarded as part of the contact element.

Inside the lower part 14, there is again a circumferential shoulder 18 on which the spacer ring 74 rests. The spring snap disk 36 is clamped between the shoulder 18 and the spacer ring 74 with its edge 78, while it rests with its center 80 on a shoulder 82 on the rivet 72. At its center 80, the spring snap disk 36 is thus clamped between the current transmission element 70 and the shoulder 82.

In Fig.5 Further down and radially further out, a shoulder 84 is provided on the rivet 72, on which the bimetallic snap disk 40 rests with its center 86. The center 86 of the bimetallic snap disk 40 rests freely on the shoulder 84. With its edge 88, the bimetallic snap disk 40 rests freely on the inner base 42 of the lower part 14.

The switching process of the Fig.5 The switch 10 shown is similar to the ones shown in Fig. 1 to 4 shown switches 10 by snapping the bimetallic snap disk 40 from its low temperature position (in Fig.5 shown) in its high temperature position or vice versa. If the bimetallic snap disk 40 snaps into its high temperature position (not shown here), the current transfer element 70 is moved from the two stationary contacts 46, 47 into Fig.5 lifted downwards, which interrupts the circuit and prevents the device to be protected from heating up any further.

1. 1. Temperaturabhängiger Schalter 10 mit einem Gehäuse 12, das ein Deckelteil 16 mit einer Oberseite 24 und ein Unterteil 14 mit einer hochgezogenen, umlaufenden Wand 28 aufweist, deren oberer Abschnitt 30 auf die Oberseite 24 des Deckteils 16 umgebogen ist und dadurch das Deckelteil 16 an dem Unterteil 14 hält, wobei außen an dem Gehäuse 12 zwei Kontaktflächen 48, 50 vorgesehen sind und in dem Gehäuse 12 ein Schaltwerk 34 angeordnet ist, das dazu eingerichtet ist, in Abhängigkeit von seiner Temperatur zwischen einem geschlossenen Zustand, in dem das Schaltwerk 34 eine elektrisch leitende Verbindung zwischen den zwei Kontaktflächen herstellt, und einem geöffneten Zustand, in dem das Schaltwerk 34 die elektrisch leitende Verbindung zwischen den zwei Kontaktflächen 48, 50 öffnet, zu schalten,
   dadurch gekennzeichnet, dass auf der Oberseite 24 des Deckelteils 16 ein Abdichtring 32 angeordnet ist, der mit dem umgebogenen, oberen Abschnitt 30 der Wand 28 in abdichtendem Kontakt steht.
2. 2. Schalter nach Ausgestaltung 1, dadurch gekennzeichnet, dass der Abdichtring 32 mit der Oberseite 24 des Deckelteils 16 und/oder dem umgebogenen, oberen Abschnitt 30 der Wand 28 stoffschlüssig verbunden ist.
3. 3. Schalter nach Ausgestaltung 2, dadurch gekennzeichnet, dass der Abdichtring 32 mit der Oberseite 24 des Deckelteils 16 und/oder dem umgebogenen, oberen Abschnitt 30 der Wand 28 verklebt, heißverprägt oder durch eine mittels Ultraschallschweißen hergestellte Schweißverbindung verschweißt ist.
4. 4. Schalter nach einem der Ausgestaltungen 1 bis 3, dadurch gekennzeichnet, dass der Abdichtring 32 als kreisringförmiger Kunststoffring ausgestaltet ist.
5. 5. Schalter nach einem der Ausgestaltungen 1 bis 4, dadurch gekennzeichnet, dass der Abdichtring 32 zwischen dem oberen Abschnitt 30 der Wand 28 und der Oberseite 24 des Deckelteils 16 eingeklemmt ist.
6. 6. Schalter nach einem der Ausgestaltungen 1 bis 5, dadurch gekennzeichnet, dass der obere Abschnitt 30 der Wand 28 zumindest teilweise in den Abdichtring 32 eindringt.
7. 7. Schalter nach einem der Ausgestaltungen 1 bis 4, dadurch gekennzeichnet, dass der obere Abschnitt 30 der Wand 28 in einem Befestigungsbereich 58 unmittelbar oder mittelbar unter Zwischenlage einer Isolierfolie 20 auf die Oberseite 24 des Deckelteils 16 drückt.
8. 8. Schalter nach Ausgestaltung 7, dadurch gekennzeichnet, dass ein radial innerer Rand 62 des Abdichtrings 32 einen kleineren Abstand von einer zentralen Mittelachse 60 des Schalters 10 hat als der Befestigungsbereich 58, und dass der Abdichtring 32, vorzugsweise mit seinem radial äußeren Rand 64, an einer Außenseite 66 des oberen Abschnitts 30 der Wand 28 anliegt, die der zentralen Mittelachse 60 des Schalters 10 zugewandt ist.
9. 9. Schalter nach Ausgestaltung 7, dadurch gekennzeichnet, dass ein radial innerer Rand 62 des Abdichtrings 32 einen gleich großen oder größeren Abstand von einer zentralen Mittelachse 60 des Schalters 10 hat als der Befestigungsbereich 58, und dass der Abdichtring 32 an einer Innenseite 68 des oberen Abschnitts 30 der Wand 28 anliegt, die von der zentralen Mittelachse 60 des Schalters 10 abgewandt ist.
10. 10. Schalter nach einem der Ausgestaltungen 1 bis 9, dadurch gekennzeichnet, dass der obere Abschnitt 30 der Wand 28 in einem Querschnitt betrachtet um mindestens 90°, vorzugsweise um mindestens 120° umgebogen ist.
11. 11. Schalter nach einem der Ausgestaltungen 1 bis 10, dadurch gekennzeichnet, dass der obere Abschnitt 30 der Wand 28 als im Querschnitt U-förmige Wulst ausgebildet ist.
12. 12. Schalter nach einem der Ausgestaltungen 1 bis 11, dadurch gekennzeichnet, dass das Unterteil 14 und das Deckelteil 16 jeweils aus elektrisch leitfähigem Material gefertigt sind und zwischen dem Deckelteil 16 und dem Unterteil 14 eine Isolierfolie 20 angeordnet ist.
13. 13. Schalter nach Ausgestaltung 12, dadurch gekennzeichnet, dass eine erste der zwei Kontaktflächen 48 an dem Deckelteil 16 angeordnet ist und eine zweite der zwei Kontaktflächen 50 an dem Unterteil 14 angeordnet ist, und dass das Schaltwerk 34 ein bewegliches Kontaktteil 38 trägt, das mit einem stationären Gegenkontakt 46 zusammenwirkt, der an einer Innenseite 26 des Deckelteils 16 angeordnet ist und mit dem ersten der zwei Kontaktflächen 48 zusammenwirkt.
14. 14. Schalter nach einem der Ausgestaltungen 1 bis 11, dadurch gekennzeichnet, dass das Unterteil 14 aus elektrisch leitfähigem Material gefertigt ist und das Deckelteil 16 aus Isoliermaterial oder PTC-Material gefertigt ist.
15. 15. Schalter nach Ausgestaltung 14, dadurch gekennzeichnet, dass die zwei Kontaktflächen 48, 50 an dem Deckelteil 16 angeordnet sind und das Schaltwerk 34 ein Stromübertragungsglied 70 trägt, das mit zwei stationären Gegenkontakten 46, 47 zusammenwirkt, die an einer Innenseite 26 des Deckelteils 16 angeordnet sind und jeweils mit einer der zwei Kontaktflächen 48, 50 zusammenwirken.
16. 16. Schalter nach einem der Ausgestaltungen 1 bis 15, dadurch gekennzeichnet, dass das Schaltwerk 34 ein Bimetallteil 40 aufweist.
17. 17. Schalter nach einem der Ausgestaltungen 1 bis 16, dadurch gekennzeichnet, dass das Schaltwerk 34 eine Feder-Schnappscheibe 36 aufweist.

The following is a list of further configurations:

1. 1. Temperature-dependent switch 10 with a housing 12, which has a cover part 16 with an upper side 24 and a lower part 14 with a raised, circumferential wall 28, the upper section 30 of which is bent over onto the upper side 24 of the cover part 16 and thereby holds the cover part 16 to the lower part 14, wherein two contact surfaces 48, 50 are provided on the outside of the housing 12 and a switching mechanism 34 is arranged in the housing 12, which is designed to switch, depending on its temperature, between a closed state in which the switching mechanism 34 establishes an electrically conductive connection between the two contact surfaces, and an open state in which the switching mechanism 34 opens the electrically conductive connection between the two contact surfaces 48, 50,
   characterized in that a sealing ring 32 is arranged on the upper side 24 of the cover part 16, which is in sealing contact with the bent upper section 30 of the wall 28.
2. 2. Switch according to embodiment 1, characterized in that the sealing ring 32 is integrally connected to the upper side 24 of the cover part 16 and/or the bent upper section 30 of the wall 28.
3. 3. Switch according to embodiment 2, characterized in that the sealing ring 32 is glued to the upper side 24 of the cover part 16 and/or the bent upper section 30 of the wall 28, hot-stamped or welded by a welded connection produced by means of ultrasonic welding.
4. 4. Switch according to one of the embodiments 1 to 3, characterized in that the sealing ring 32 is designed as a circular ring-shaped plastic ring.
5. 5. Switch according to one of the embodiments 1 to 4, characterized in that the sealing ring 32 is clamped between the upper section 30 of the wall 28 and the upper side 24 of the cover part 16.
6. 6. Switch according to one of the embodiments 1 to 5, characterized in that the upper portion 30 of the wall 28 penetrates at least partially into the sealing ring 32.
7. 7. Switch according to one of the embodiments 1 to 4, characterized in that the upper section 30 of the wall 28 presses in a fastening region 58 directly or indirectly with the interposition of an insulating film 20 onto the upper side 24 of the cover part 16.
8. 8. Switch according to embodiment 7, characterized in that a radially inner edge 62 of the sealing ring 32 has a smaller distance from a central axis 60 of the switch 10 than the fastening region 58, and that the sealing ring 32, preferably with its radially outer edge 64, rests on an outer side 66 of the upper section 30 of the wall 28, which faces the central axis 60 of the switch 10.
9. 9. Switch according to embodiment 7, characterized in that a radially inner edge 62 of the sealing ring 32 has an equal or greater distance from a central axis 60 of the switch 10 than the fastening region 58, and that the sealing ring 32 rests against an inner side 68 of the upper section 30 of the wall 28, which faces away from the central axis 60 of the switch 10.
10. 10. Switch according to one of the embodiments 1 to 9, characterized in that the upper portion 30 of the wall 28 is bent by at least 90°, preferably by at least 120°, when viewed in a cross-section.
11. 11. Switch according to one of the embodiments 1 to 10, characterized in that the upper portion 30 of the wall 28 is designed as a bead with a U-shaped cross section.
12. 12. Switch according to one of the embodiments 1 to 11, characterized in that the lower part 14 and the cover part 16 are each made of electrically conductive material and an insulating film 20 is arranged between the cover part 16 and the lower part 14.
13. 13. Switch according to embodiment 12, characterized in that a first of the two contact surfaces 48 is arranged on the cover part 16 and a second of the two contact surfaces 50 is arranged on the lower part 14, and that the switching mechanism 34 carries a movable contact part 38 which cooperates with a stationary counter-contact 46 which is arranged on an inner side 26 of the cover part 16 and cooperates with the first of the two contact surfaces 48.
14. 14. Switch according to one of the embodiments 1 to 11, characterized in that the lower part 14 is made of electrically conductive material and the cover part 16 is made of insulating material or PTC material.
15. 15. Switch according to embodiment 14, characterized in that the two contact surfaces 48, 50 are arranged on the cover part 16 and the switching mechanism 34 carries a current transmission element 70 which cooperates with two stationary counter contacts 46, 47 which are arranged on an inner side 26 of the cover part 16 and each cooperate with one of the two contact surfaces 48, 50.
16. 16. Switch according to one of the embodiments 1 to 15, characterized in that the switching mechanism 34 has a bimetal part 40.
17. 17. Switch according to one of the embodiments 1 to 16, characterized in that the switching mechanism 34 has a spring snap disk 36.

Claims (12)

Temperature-dependent switch (10) with a housing (12) which has a cover part (16) with an upper side (24) and a lower part (14) with a raised, circumferential wall (28), the upper section (30) of which is bent over onto the upper side (24) of the cover part (16) and thereby holds the cover part (16) to the lower part (14), wherein two contact surfaces (48, 50) are provided on the outside of the housing (12) and a switching mechanism (34) is arranged in the housing (12), which is designed to switch, depending on its temperature, between a closed state in which the switching mechanism (34) establishes an electrically conductive connection between the two contact surfaces, and an open state in which the switching mechanism (34) opens the electrically conductive connection between the two contact surfaces (48, 50), wherein a sealing ring (32) is arranged on the upper side (24) of the cover part (16), which sealing ring is connected to the bent upper section (30) of the wall (28) is in sealing contact,
characterized in that the upper section (30) of the wall (28) presses in a fastening area (58) directly or indirectly with the interposition of an insulating film (20) on the upper side (24) of the cover part (16), wherein (i) a radially inner edge (62) of the sealing ring (32) is at a smaller distance from a central axis (60) of the switch (10) than the fastening region (58), the sealing ring (32) resting with its radially outer edge (64) on an outer side (66) of the upper section (30) of the wall (28) which faces the central axis (60) of the switch (10), or (ii) a radially inner edge (62) of the sealing ring (32) is at an equal or greater distance from a central axis (60) of the switch (10) than the fastening region (58), the sealing ring (32) abutting an inner side (68) of the upper portion (30) of the wall (28) facing away from the central axis (60) of the switch (10). Switch according to claim 1, characterized in that the sealing ring (32) is materially connected to the upper side (24) of the cover part (16) and/or the bent upper section (30) of the wall (28). Switch according to claim 2, characterized in that the sealing ring (32) is glued, hot-stamped or welded to the upper side (24) of the cover part (16) and/or the bent upper section (30) of the wall (28) by means of a welded connection produced by means of ultrasonic welding. Switch according to one of claims 1 to 3, characterized in that the sealing ring (32) is designed as a circular plastic ring. Switch according to one of claims 1 to 4, characterized in that the upper portion (30) of the wall (28) is bent by at least 90°, preferably by at least 120°, when viewed in a cross-section. Switch according to one of claims 1 to 5, characterized in that the upper portion (30) of the wall (28) is designed as a bead with a U-shaped cross section. Switch according to one of claims 1 to 6, characterized in that the lower part (14) and the cover part (16) are each made of electrically conductive material and an insulating film (20) is arranged between the cover part (16) and the lower part (14). Switch according to claim 7, characterized in that a first of the two contact surfaces (48) is arranged on the cover part (16) and a second of the two contact surfaces (50) is arranged on the lower part (14), and that the switching mechanism (34) carries a movable contact part (38) which cooperates with a stationary counter-contact (46) which is arranged on an inner side (26) of the cover part (16) and cooperates with the first of the two contact surfaces (48). Switch according to one of claims 1 to 6, characterized in that the lower part (14) is made of electrically conductive material and the cover part (16) is made of insulating material or PTC material. Switch according to claim 9, characterized in that the two contact surfaces (48, 50) are arranged on the cover part (16) and the switching mechanism (34) carries a current transmission element (70) which cooperates with two stationary counter-contacts (46, 47) which are arranged on an inner side (26) of the cover part (16) and each cooperate with one of the two contact surfaces (48, 50). Switch according to one of claims 1 to 10, characterized in that the switching mechanism (34) has a bimetal part (40). Switch according to one of claims 1 to 11, characterized in that the switching mechanism (34) has a spring snap disk (36).

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