Temperature-dependent switch

Abstract

Temperature-dependent switch (10) with a housing (12) comprising a cover part (18) and a base part (16), wherein an insulating film (22) is arranged between the cover part (18) and the base part (16), with a first outer contact surface (48) provided on the outside of the housing (12), a second outer contact surface (50) provided on the outside of the housing (12), and with a temperature-dependent switching mechanism (14) arranged in the housing (12), which establishes or opens an electrically conductive connection between the first and the second outer contact surfaces (48, 50) depending on its temperature, wherein the insulating film (22) is at least partially coated or printed with a sealant (26) which contacts the cover part (18) and / or the base part (16) in a sealing area (29) to seal the housing (12).

Description

[0001] The present invention relates to a temperature-dependent switch with a housing having a cover part and a lower part, wherein an insulating film is arranged between the cover part and the lower part, with a first outer contact surface provided on the outside of the housing, a second outer contact surface provided on the outside of the housing, and with a temperature-dependent switching mechanism arranged in the housing, which establishes or opens an electrically conductive connection between the first and the second outer contact surface depending on its temperature.

[0002] The present invention further relates to a method for producing a temperature-dependent switch.

[0003] A generic switch is known, for example, from DE 10 2015 114 248 B4. Another generic switch, which forms the basis for the preambles of claims 1 and 12, is known from DE 10 2011 119 633 B3. Further exemplary temperature-dependent switches are known from EP 1 239 505 A2 and WO 02 / 086927 A1.

[0004] The well-known temperature-dependent switch serves, in a conventional manner, to monitor the temperature of a device. For this purpose, it is brought into thermal contact with the device to be protected, for example, via one of its outer surfaces, so that the temperature of the device to be protected influences the temperature of the switching mechanism.

[0005] The switch is typically connected electrically in series to the supply circuit of the device to be protected via connecting leads soldered to its two outer contact surfaces, so that below the response temperature of the switch the supply current of the device to be protected flows through the switch.

[0006] The known switch comprises a base part with an inner circumferential shoulder, on which the cover part rests with an insulating foil interposed. The cover part is firmly held on this circumferential shoulder by a raised, circumferential wall of the base part, which is bent radially inward at its upper section.

[0007] The temperature-dependent switching mechanism of the switch known from DE 10 2015 114 248 B4 comprises a spring-loaded snap-action disc carrying a movable contact part, as well as a bimetallic snap-action disc fitted over the movable contact part. The spring-loaded snap-action disc presses the movable contact part against a stationary counter-contact on the inside of the cover part. The edge of the spring-loaded snap-action disc rests against the lower part of the housing, allowing the electrical current to flow from the lower part through the spring-loaded snap-action disc and the movable contact part into the stationary counter-contact and from there into the cover part.

[0008] In the design variants of the switch known from DE 10 2015 114 248 B4, a bimetal part or a bimetal snap-action disc is provided for the temperature-dependent switching function, which lies in the switching mechanism without any force below its switching temperature.

[0009] For the purposes of the present invention, a bimetallic part or bimetallic snap-action disc is understood to be a multi-layer, active, sheet-metal component consisting of two, three, or four interconnected components with different thermal expansion coefficients. The individual layers of metals or metal alloys are bonded or positively connected and are achieved, for example, by rolling.

[0010] Such a bimetallic part has a first stable geometric configuration in its low-temperature position and a second stable geometric configuration in its high-temperature position, between which it switches depending on the temperature according to a hysteresis. When the temperature changes above its response temperature or below its recovery temperature, the bimetallic part snaps into the other geometric configuration. The bimetallic part is therefore often referred to as a snap disk, and in plan view it typically has an elongated, oval, or circular shape.

[0011] If the temperature of the bimetal part, typically designed as a bimetallic disc, rises above the response temperature due to a temperature increase in the device to be protected, the bimetal disc switches from its low-temperature configuration to its high-temperature configuration. The bimetal disc works against the spring-loaded snap-action disc to lift the movable contact part from the stationary mating contact or the current transfer element from the two stationary mating contacts, thus opening the switch and shutting down the device to be protected, preventing it from heating up further.

[0012] In these designs, the bimetallic disc is preferably mechanically supported without force below its transition temperature, and the bimetallic disc is also not used to conduct the current. This has the advantage that the bimetallic disc has a longer mechanical service life and that the switching point, i.e., the transition temperature of the bimetallic disc, remains unchanged even after many switching cycles.

[0013] If low demands are placed on mechanical reliability or transition temperature stability, the bimetallic disc can also assume the function of the spring-loaded snap disc and possibly even the current transfer element, so that the switching mechanism comprises only one bimetallic disc, which then carries the movable contact part or has two contact surfaces instead of the current transfer element. In this case, the bimetallic disc not only provides the closing pressure of the switch, but also conducts the current when the switch is closed.

[0014] In most temperature-dependent switches, the housing is usually protected from the ingress of contaminants by a seal that is applied before or after the connection of terminal lugs or connecting cables to the external terminals.

[0015] DE 41 39 091 A1 discloses overmolding the external terminals with a one-component thermoset. DE 10 2009 039 948 A1 also discloses encapsulating terminal lugs with an epoxy resin. It is also known to coat the switches with an impregnating varnish or protective varnish after soldering the connecting leads or terminal lugs.

[0016] To prevent paint, resin or other liquids from penetrating the interior of the housing, the cover part of the switch known from DE 196 23 570 A1 is provided with a sealing agent in the form of a circumferential bead that runs radially outwards on the underside of the cover part. When the upper section of the circumferential wall of the base part is bent over, this circumferential bead constricts the insulating film. Although this ensures a better seal, in many cases paint still penetrates into the interior of the housing. The insulating film lying between the base part and the cover part is pulled up laterally between the wall of the base part and the cover part and its edge area is folded over onto the upper side of the cover part. The rigid insulating film becomes wavy due to the folding and forms rosettes that cannot be reliably sealed due to the flat upper section of the circumferential wall of the base part pressing against them.There is a risk of coating varnish penetrating the interior of the switch through the rosettes. DE 196 23 570 A1 attempts to mitigate this problem with the aforementioned bead.

[0017] DE 10 2013 102 089 B4 describes a switch similar to the one known in DE 196 23 570 A1. This switch has a spacer ring between the shoulder in the base and the cover, which allows for a larger switching distance between the movable contact part and the stationary counter-contact. To eliminate the sealing problem known from the switch described in DE 196 23 570 A1, the edge area of ​​the insulating film in this switch is cut in a V-shape from the outside, which greatly reduces waviness and improves sealing.

[0018] DE 10 2013 102 006 B4 also describes a switch of a similar design. This switch has a cover made of PTC material. Due to the lack of pressure stability of this PTC cover, the radially inwardly bent upper section of the circumferential wall of the lower part cannot adequately seal the known switch against the ingress of contaminants. For this reason, the bent upper section of the circumferential wall must be sealed against the upper side of the cover with silicone, which often causes problems. DE 10 2013 102 006 B4 solves this problem by providing a cover film that rests solely on the upper side of the PTC cover and into which the bent upper section of the circumferential wall of the lower part, which lies flat against the cover film, penetrates. The end face of the upper section of the circumferential wall faces away from the cover film.However, the flat upper section of the surrounding wall of the lower part often does not provide the desired sealing.

[0019] A switch can also be provided with a cover film and an insulating film, as shown, for example, in DE 10 2013 102 089 B4. An insulating cover film, made of Nomex ®<, for example, is arranged on the top side of the cover part of this switch. Its edge extends radially outward to the insulating film, which is made of Kapton ®<, for example. Nomex ®< and Kapton ®< are made of aramid paper and aromatic polyimides, respectively.

[0020] Despite the various sealing measures, the known switches repeatedly experience sealing problems, which are due, among other things, to the fact that the relatively stiff insulating film cannot achieve a permanent seal by bending the upper section of the surrounding edge of the lower part.

[0021] In the switch known from DE 10 2015 114 248 B4 mentioned above, this sealing problem is solved by a circumferentially closed cutting burr formed integrally with the shoulder in the lower part. This cutting burr penetrates the insulating film (if present) from below or directly into the cover part from below. The penetration of this closed cutting burr into the insulating film or the cover part creates a secure seal between the lower part and the cover part.

[0022] The cutting burr is created during the manufacturing of the lower part. It is formed integrally with the shoulder in the lower part. In this case, the lower part is usually manufactured as a turned part, so the cutting burr is a turning groove that is created during the turning of the lower part.

[0023] However, to ensure sufficient tightness, these grooves must be manufactured with great precision. Manufacturing the base part, including these precisely manufactured grooves, is very complex and thus increases production costs. Another problem with this solution is that the grooves are often damaged before the switch is installed. The individual components of the switch housing are typically stored in bulk before assembly. This can easily lead to the grooves becoming blunt or even completely worn away.

[0024] Against this background, the object of the present invention is to eliminate or at least reduce the above-mentioned sealing problems in the known switch in a structurally simple and inexpensive manner.

[0025] According to a first aspect of the present invention, starting from the switch mentioned at the outset, this object is achieved in that the insulating film is only partially coated or printed with a sealant in a sealing region on its upper side facing the cover part and / or on its underside facing the lower part, which sealant contacts the cover part and / or the lower part in the sealing region to seal the housing, and that the sealant forms a self-contained contour on the upper side and / or on the underside of the insulating film.

[0026] The above-mentioned object is achieved according to a second aspect of the present invention by a method for producing a temperature-dependent switch comprising the following steps: Providing a lower part of a housing; providing a cover part of the housing; providing a temperature-dependent switching mechanism which, in the assembled state of the switch, establishes or opens an electrically conductive connection between a first outer contact surface provided on the outside of the housing and a second contact surface provided on the outside of the housing, depending on its temperature; providing an insulating film; coating or printing the insulating film with a sealant;and mounting the housing, wherein the switching mechanism is arranged in the housing and the cover part is mounted on the lower part with the insulating film interposed in such a way that the sealing means for sealing the housing contacts the cover part and / or the lower part in a sealing area, wherein the insulating film is only partially coated or printed with the sealing means in the sealing area on its upper side facing the cover part and / or on its underside facing the lower part in such a way that the sealing means forms a self-contained contour on the upper side and / or on the underside of the insulating film.

[0027] By coating or printing the insulating film with a sealant according to the invention, the sealing of the housing interior can be significantly improved. In this case, the insulating film not only serves to electrically insulate the cover part from the base of the housing. Due to the coating of the insulating film with the sealant, the insulating film also has a strong mechanical sealing effect. The risk of paint, resin, or other liquids penetrating the housing interior during switch production is thus significantly reduced.

[0028] The additional sealant applied to the insulating foil ensures a deep pore seal. Without the sealant, the insulating foil in conventional switches only seals due to the positive fit or the contact pressure that occurs between the cover and base sections and the insulating foil arranged between them.

[0029] A further advantage of the solution according to the invention is the very simple handling for applying the sealant to the switch housing. Due to the fact that the sealant is already applied to the insulating film before the switch is installed, the insulating film can be easily applied between the cover part and the base part of the housing, as is otherwise usual. An additional work step, such as that required for applying a separate sealant, can be eliminated. The locations where a seal between the cover part and the base part is particularly necessary are known. It is also known at which points the insulating film is clamped between the cover part and the base part during assembly of the switch.Accordingly, the sealant can be applied to the insulation foil at the appropriate locations before the insulation foil is installed, in order to contact the cover part and / or the bottom part of the housing as desired in the sealing area after installation.

[0030] According to the invention, the sealant is only partially applied to the insulating film in this sealing area.

[0031] Various common coating processes can be used to apply the sealant to the insulating film, such as painting, spray coating, vapor deposition, etc. Various printing techniques known from the state of the art can also be used.

[0032] According to a preferred embodiment, the sealant is made of plastic or wax.

[0033] In addition to being inexpensive to obtain, various plastics or wax have the advantage of being relatively viscous at room temperature, meaning they don't melt when the insulating film is installed in the switch and thus don't flow into unwanted areas. Wax, in particular, adheres relatively well to the insulating film, so the risk of the sealant separating from the insulating film during installation is relatively low. Furthermore, wax conforms very well to different shapes, which is particularly advantageous when sealing edges or corners, as the wax, together with the insulating film, adapts to the respective shape of the cover and / or base. This ensures optimal sealing.

[0034] According to a further embodiment, the sealant is made of a thermoplastic, a thermoset or an elastomer.

[0035] Furthermore, it is preferred that the sealant be a subsequently heat-activated sealant that was activated after its installation in the housing. Accordingly, in the method according to the invention, it is preferred that the switch be heated to activate the sealant after the housing has been mounted.

[0036] By subsequently heating the switch in this way, for example, part of the sealant can be liquefied, allowing it to reach the desired areas to be sealed even more easily. Compared to a sealant that is already liquid from the outset, handling a sealant that has been subsequently activated by heating is significantly easier during switch installation. Sealants that are liquid from the outset could potentially flow into undesired areas during the installation of the insulating film, causing contamination and / or other assembly complications.

[0037] According to a further embodiment, the insulating film comprises a polyimide or an aromatic polyamide. Preferably, the insulating film consists of a polyimide or an aromatic polyamide.

[0038] The positive suitability of such materials for insulating films in temperature-dependent switches has already been proven many times in practice. Typically, insulating films for this type of application are materials with trade names such as Kapton® or Nomex®.

[0039] The thickness of the insulating film can vary depending on the application. If it is comparatively thick, it is often referred to as an "insulating disc." However, such an insulating disc is also subsumed under the term "insulating film" in this context.

[0040] According to a further embodiment, it is preferred that the sealing means forms a closed, preferably circular contour on the insulating film.

[0041] The closed contour of the sealant has the advantage that, with the help of the sealant applied to the insulating foil, a sealing effect can be created along the entire circumference of the switch. Typically, such temperature-dependent switches are switches with rotationally symmetrical housings, so a sealing effect along the entire circumference of the housing is required.

[0042] The contour of the sealant is preferably adapted to the shape of the housing. Thus, the sealant does not necessarily have to be applied to the insulating film in a circular pattern, but can also be applied to the insulating film in an elliptical or oval area, for example, if the housing also has a corresponding shape.

[0043] According to a further embodiment, the insulating film has a centrally arranged hole which is surrounded by the closed contour.

[0044] Preferably, the sealing means is arranged at a distance from the central hole. A portion of the switch mechanism can protrude through the hole in the insulating foil, thus establishing an electrically conductive connection between the cover part and the base part of the switch.

[0045] The sealant is preferably radially spaced from this hole, since its sealing effect is particularly required in a sealing area located in the area of ​​the edge of the cover part, since the insulating film is folded over or bent here and, in particular, a type of rosette formation of the insulating film can occur at these points, which can lead to mechanical leaks without the sealant.

[0046] According to one embodiment, the insulating film is coated or printed with the sealant on one side, either on its upper side facing the cover part or on its underside facing the lower part.

[0047] Such a one-sided coating of the insulating film is cost-effective and can be sufficient to achieve the desired sealing effect. This is particularly the case if, in addition to the sealant applied to the insulating film, additional devices are present to seal the interior of the housing.

[0048] According to one embodiment, it is provided, for example, that the insulating film is coated or printed with the sealant on one side, on its upper side facing the cover part, and that a circumferentially closed cutting burr is formed on the lower part, which penetrates into a lower side of the insulating film opposite the upper side.

[0049] Such a cutting burr, which can be configured, for example, as rotary grooves, is known from DE 10 2015 114 248 B4. In combination with the sealant coating of the insulating film according to the invention, such a cutting burr, which cuts into the insulating film from the side opposite the sealant, can ensure optimal sealing of the housing interior.

[0050] It is understood that the combination of sealant coatings and cutting burrs can also be used in the switch according to the invention in a reverse arrangement. For example, the insulating film can be coated or printed with the sealant on one side, on its underside facing the base part, and a circumferentially closed cutting burr can be formed on the cover part, which penetrates or cuts into an upper side of the insulating film opposite the underside.

[0051] According to a further embodiment, it is provided that the insulating film is coated or printed with the sealant on both sides, both on its upper side facing the cover part and on its underside facing the lower part.

[0052] This offers significant cost advantages compared to the combined solution of sealant coating and cutting burr. It has been shown that coating the insulating film with sealant on both sides in this way also produces a very good seal. The sealant applied to the top of the insulating film creates a seal between the insulating film and the cover of the housing. The sealant applied to the underside of the insulating film, on the other hand, creates a seal between the insulating film and the bottom of the housing. This ensures appropriate sealing on both sides of the insulating film.

[0053] Preferably, an edge of the cover part presses on the lower part in the sealing area and the intermediate layer of the insulating film.

[0054] In other words, the sealant is preferably arranged on the insulating film in such a way that, in the fully assembled switch, it lies in an area where the cover part presses against the base part. This pressure is typically the closing pressure with which the cover part is pressed against the base part in the assembled state of the switch. This pressure can lead to plastic deformation of the sealant, which further improves its sealing effect.

[0055] It is preferably provided that the lower part has a circumferential wall, the upper section of which engages over the cover part, that a circumferential shoulder is provided in the lower part, on which shoulder the cover part rests with the insulating film interposed, wherein the upper section of the lower part presses the cover part onto the circumferential shoulder, and that the sealing region is arranged on the circumferential shoulder and / or on a lower edge of the cover part facing the circumferential shoulder.

[0056] The greatest deformation of the insulating film occurs in the area of ​​this shoulder, or in the area of ​​the lower, radially outer edge of the cover part. In this area in particular, a type of wrinkle and / or rosette formation can occur in the insulating film, which can significantly impair the sealing effect. Thus, the sealant coating according to the invention on the insulating film offers a huge advantage, particularly in this area, since the sealant can counteract the aforementioned wrinkle or rosette formation in this area, or rather, since the sealant can ensure sealing of this sealing area despite these wrinkles or rosettes.

[0057] It is further preferred that the switching mechanism carries a movable contact part that interacts with a stationary counter-contact that is arranged on an underside of the cover part facing the lower part and interacts with the first outer contact surface. The movable contact part moves together with the switching mechanism during a switching operation. In the low-temperature position of the switching mechanism, the movable contact part is pressed against the stationary counter-contact. The circuit is then closed via the switch. In the low-temperature position of the switching mechanism, the movable contact part is lifted from the stationary counter-contact. The circuit is then open. This basic arrangement is already known from many examples of such temperature-dependent switches.

[0058] Regardless of the design variant of the switch, it is preferred that the switching mechanism has a bimetallic part.

[0059] The bimetal part can be a round, preferably circular, bimetal snap-action disc, although it is also possible to use an elongated, single-ended bimetal spring as the bimetal part. In simple switches, the bimetal part can also be used to conduct current.

[0060] Furthermore, it is preferred that the rear derailleur additionally has a spring snap disc.

[0061] This spring-loaded snap-action disc can, for example, support the movable contact part and conduct the current through the closed switch, providing contact pressure when closed. This relieves the bimetallic part of both the current conduction and the mechanical load when the switch is closed.

[0062] The present invention is particularly well suited for at least approximately round temperature-dependent switches that are round, circular, or oval in plan view of the base or cover. However, other housing shapes can also be used in principle.

[0063] 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.

[0064] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 is a schematic sectional view of a first embodiment of the switch according to the invention in a first switching position; Fig. 2 is a schematic sectional view of the Fig. 1 shown first embodiment of the switch according to the invention in a second switching position; Fig. 3 a schematic sectional view of a second embodiment of the switch according to the invention in the first switching position; Fig. 4 a schematic sectional view of a third embodiment of the switch according to the invention in the first switching position; Fig. 5 a schematic sectional view of a fourth embodiment of the switch according to the invention in the first switching position; Fig. 6 a schematic sectional view of a fifth embodiment of the switch according to the invention in the first switching position; and Fig. 7 a schematic plan view of an insulating film that can be used in the switch according to the invention.

[0065] In Fig. 1 In a schematic, sectional side view, a switch 10 is shown which is rotationally symmetrical in plan view and preferably has a circular shape.

[0066] The switch 10 has a housing 12 in which a temperature-dependent switching mechanism 14 is arranged. The housing 12 comprises a pot-shaped lower part 16 and a cover part 18, which is held to the lower part 16 by a bent or flanged edge 20.

[0067] The lower part 16 and the cover part 18 are made of an electrically conductive material, preferably metal. The cover part 18 rests on a shoulder 24 extending circumferentially inside the lower part 16, with an insulating film 22 interposed therebetween. The upper edge 20 of the lower part 16 is bent radially inward in such a way that it presses the cover part 18 onto the circumferential shoulder 24, with the insulating film 22 interposed therebetween.

[0068] The insulating film 22 provides electrical insulation of the cover part 18 from the base part 16. In addition, the insulating film 22 also provides a mechanical seal that prevents liquids or contaminants from entering the housing interior from the outside.

[0069] The insulating film 22 runs inside the housing 12 parallel to the cover part 18 along its underside 25. From there, it extends laterally between the cover part 18 and the circumferential shoulder 24 upwards and out of the housing 12 beyond the top side 23 of the cover part 18. The bent or flanged upper edge 20 of the lower part 16 lies flat on the upper edge region of the insulating film 22 and presses it toward the top side 23 of the cover part 18.

[0070] The insulating film 22 is coated with a sealing agent 26. The sealing agent 26 is preferably a plastic (thermoplastic, thermoset, or elastomer) or a wax.

[0071] In the Fig. 1 In the first embodiment of the switch 10 shown, the sealing means 26 is applied to an upper side 27 of the insulating film 22, which faces the cover part 18. In the assembled state of the switch 10, the sealing means 26 contacts the cover part 18 in a sealing area 29. This sealing area 29 is in Fig. 1 highlighted by a circle.

[0072] In this exemplary embodiment, the sealing region 29 extends circumferentially along the outer, lower edge of the cover part 18 and, starting therefrom, a short distance vertically upwards along the outer circumference of the cover part 18 and radially inwards along a radially outer part of the underside 25 of the cover part 18. Viewed in cross section, the sealing means 26 is thus substantially L-shaped.

[0073] Fig. 7 shows a schematic top view of the insulating film 22. As can be seen therefrom, the sealing means 26 is applied to the insulating film 22 in a circular region 31. The sealing means 26 preferably forms a closed contour. This ensures a seal along the entire circumference between the cover part 18 and the lower part 16. It is understood that, depending on the shape of the insulating film 22, the region 31 does not necessarily have to be circular, but can also be oval or elliptical, for example.

[0074] The region 31 in which the sealant 26 is applied to the insulating film 22 is positioned such that the sealant 26 is automatically arranged in the desired sealing region 29 upon assembly of the insulating film 22 in the housing 12. The region 31 is preferably arranged at a radial distance from a hole 33 located centrally in the insulating film 22. This hole 33 enables movement of a portion of the temperature-dependent switching mechanism of the switch 10 through the insulating film 22, as will be explained in more detail below.

[0075] Preferably, the sealant 26 is a subsequently activated sealant by heating, which is only activated after its installation in the housing 12. This means that the switch 10 is heated slightly after installation of the insulating film 22, preferably in an oven, whereby at least a portion of the sealant 26 melts or at least partially liquefies in order to adapt even better to the shape of the insulating film 22 and the shape of the cover part 18 in the sealing area 29. Subsequent cooling causes the sealant 26 to solidify again. This significantly improves the sealing effect of the sealant 26. The sealant 26 ensures a pore-deep seal in the sealing area 29.

[0076] On the upper side 23 of the cover part 18 in the Fig. 1 shown switch 10, a further insulating cover 34 is also provided, which extends from a central region radially outwards to the insulating film 22.

[0077] The switching mechanism 14 has a temperature-independent spring part 28 designed as a spring snap-action disc, and a temperature-dependent bimetal part 30 designed as a bimetallic snap-action disc. The spring part 28 is preferably designed as a bistable spring disc. The spring disc 28 therefore has two temperature-independent, stable geometric configurations. Fig. 1 their first geometric configuration is shown.

[0078] The temperature-dependent bimetallic disc 30 is preferably designed as a bistable snap-action disc. The bimetallic disc 30 has two temperature-dependent configurations, a geometric high-temperature configuration and a geometric low-temperature configuration. Fig. 1 In the first switching position of the switching mechanism 14 shown, the bimetallic disc 30 is in its low-temperature configuration.

[0079] The spring snap-action disc 28 rests with its edge 32 on an inner bottom surface 35 of the lower part 16. The inner bottom surface 35 is essentially concave and at the point where the edge 32 of the spring snap-action disc 28 rests in the Fig. 1 shown first switching position, slightly raised compared to the central area of ​​the inner bottom surface 35. The bimetallic disc 30 lies with its edge 36 in its Fig. 1 shown low temperature configuration on the spring snap disk 28.

[0080] The spring-loaded snap-action disc 28 is secured at its center 38 to a movable contact element 40 of the switching mechanism 14. The bimetallic disc 30 is also secured at its center 42 to this contact element 40. Thus, the temperature-dependent switching mechanism 14 is a captive unit comprising the contact element 40, the spring-loaded snap-action disc 28, and the bimetallic disc 30. When assembling the switch 10, the switching mechanism 14 can be inserted directly into the lower part 16 as a unit.

[0081] On its upper side, the movable contact member 40 has a movable contact part 44. The movable contact part 44 cooperates with a stationary counter-contact 46, which is arranged on the underside 25 of the cover part 18. The upper side 23 of the cover part 18, which is electrically connected to the stationary counter-contact 46, serves as the first contact surface 48 in this exemplary embodiment. The outer side of the lower part 16 serves as the second outer contact surface 50. For example, the outer bottom surface or the outer side of the bent-over upper edge 20 of the lower part 16 can serve as the second outer contact surface 50.

[0082] In the Fig. 1 In the closed switching position of the switch 10 shown, the movable contact part 44 is pressed by the spring snap-action disc 28 against the stationary counter-contact 46. Because the electrically conductive spring snap-action disc 28 is connected with its edge 32 to the lower part 16, an electrically conductive connection is established between the two outer contact surfaces 48, 50.

[0083] If the temperature inside the switch 10 now rises above the switching temperature of the bimetal disc 30, the latter snaps from its Fig. 1 shown convex low-temperature configuration into its Fig. 2 shown concave high-temperature configuration.

[0084] In the Fig. 2 In the high-temperature configuration shown, the bimetallic disc 30 rests with its edge 36 on the underside 51 of the insulating foil 22 and presses the movable contact element 40 downwards with its center 42. This lifts the movable contact part 44 from the stationary counter-contact 46. The spring snap-action disc 28 snaps from its Fig. 1 shown, first geometrically stable configuration into its Fig. 2 shown, second geometrically stable configuration.

[0085] Since the switch is now open and the power supply to the device to be protected is interrupted, the device to be protected and thus also the switch 10 can cool down again. When the temperature inside the switch 10 then cools down again to a temperature below the reset temperature of the bimetal disc 30, the disc snaps back out of its Fig. 2 shown high-temperature configuration back to its Fig. 1 shown low-temperature configuration. The spring-loaded snap-action disc 28 also snaps back into its first geometrically stable configuration and brings the movable contact part 44 back into contact with the stationary counter-contact 46. The switch 10 or the circuit is then closed again.

[0086] Fig. 3 shows a second embodiment of the switch 10 according to the invention. The switch 10 is shown in its first switching position. In comparison to the Fig. 1 and 2 In the first embodiment of the switch 10 shown, the sealing means 26 is in accordance with the Fig. 3 shown second embodiment is now applied to the underside 51 of the insulating film 22 facing the lower part 16 and seals in the sealing area 29, in particular between the insulating film 22 and the lower part 16 of the housing 12.

[0087] In the Fig. 4 In the third exemplary embodiment of the switch 10 shown, the insulating film 22 is coated not only on one side, but on both sides with a sealant 26, 26'. Accordingly, the sealant 26, 26' is applied both to the upper side 27 facing the cover part 18 and to the underside 51 of the insulating film 22 facing the lower part 16. Preferably, the sealant 26, 26' is applied to the insulating film 22 on both sides in a circular ring-shaped region 31. This further improves the sealing effect, since the sealant 26, 26' in the sealing region 29 seals both the region between the outer lower edge of the cover part and the insulating film and the region between the insulating film 22 and the circumferential shoulder 24 of the lower part 16.

[0088] Fig. 5 shows a further embodiment of the switch 10 according to the invention. Here, too, the switch 10 is shown in its first, closed switching position. In the Fig. 5 In the embodiment shown, the sealing means 26 is similar to that shown in Fig. 1 and 2shown first embodiment, again applied to the top side 27 of the insulating film 22. On the underside 51 of the insulating film 22, a cutting burr 52 provides additional sealing between the insulating film 22 and the lower part 16. This cutting burr 52 is designed as a circumferential cutting burr with a closed contour. The cutting burr 52 is preferably designed as a rotary groove arranged on the top side of the shoulder 24. The cutting burr 52 is preferably formed integrally with the lower part 16. On its top side, the cutting burr has a pointed cutting edge with which the cutting burr 52 penetrates into the underside 51 of the insulating film 22. The cutting burr 52 thus cuts at least partially into the insulating film 22 and thus provides a mechanical barrier.In combination with the sealant 26 arranged on the upper side 27 of the insulating film 22, the cutting burr 52 ensures a very good seal on both sides of the insulating film 22.

[0089] The position of the sealant 26 and the cutting burr 52 can, in contrast to the Fig. 5 shown embodiment can also be swapped. Such an embodiment is shown in Fig. 6 shown. Here, the cutting burr 52 is arranged on the cover part 18, and the sealing means 26 is arranged on the underside 51 of the insulating film 22. The cutting burr 52 cuts from above into the upper side 27 of the insulating film 22 and seals the sealing area 29 between the cover part 18 and the insulating film 22, whereas the sealing means 26 seals the sealing area 29 between the insulating film 22 and the lower part 16.

[0090] Furthermore, it is possible to arrange the cutting burr 52 and the sealing means 26 on one and the same side of the insulating film 22. The cutting burr 52 would then cut into a part of the sealing means 26. This would also lead to a very good sealing effect. For example, it would be possible to provide such a cutting burr 52 on both the lower part 16 and the cover part 18, so that one cutting burr 52 penetrates the insulating film 22 from below and a second cutting burr penetrates the insulating film 22 from above. In this case, the sealing means 26, 26' could also be arranged as in Fig. 4 shown arranged on both sides of the insulating foil 22.

Claims

1. Temperature-dependent switch (10) having a housing (12), which comprises a cover part (18) and a lower part (16), wherein an insulating foil (22) is arranged between the cover part (18) and the lower part (16), having a first external contact surface (48) provided externally on the housing (12), a second external contact surface (50) provided externally on the housing (12), and having a temperature-dependent switching mechanism (14) arranged in the housing (12), which, depending on its temperature, establishes or opens an electrically conductive connection between the first and the second external contact surfaces (48, 50), characterized in that the insulating foil (22) is only partially coated or printed with a sealing agent (26) in a sealing region on its upper side (27) facing the cover part (18) and / or on its lower side (51) facing the lower part (16), which sealing agent, for sealing the housing (12), contacts the cover part (18) and / or the lower part (16) in the sealing area (29), and in that the sealing agent (26) forms a closed contour (31) on the upper side (27) and / or the lower side (51) of the insulating foil (22).

2. The temperature-dependent switch according to claim 1, characterized in that the sealing agent (26) is made of plastic or wax.

3. The temperature-dependent switch according to claim 1 or 2, characterized in that the sealing agent (26) is made of a thermoplastic, a thermoset or an elastomer.

4. The temperature-dependent switch according to one of claims 1-3, characterized in that the sealing agent (26) is a sealing agent that is retroactively activated by heating and that was activated after its installation in the housing (12).

5. The temperature-dependent switch according to one of claims 1-4, characterized in that the insulating foil (22) comprises a polyimide or an aromatic polyamide.

6. The temperature-dependent switch according to one of claims 1-5, characterized in that the closed contour (31) is circular.

7. The temperature-dependent switch according to claim 6, characterized in that the insulating foil (22) comprises a centrally arranged hole (33) that is surrounded by the closed contour (31).

8. The temperature-dependent switch according to one of claims 1-7, characterized in that the insulating foil (22) is coated or printed with the sealing agent (26) on one side, namely on its upper side (27) facing the cover part (18), and in that a circumferentially closed cutting burr (52) is provided on the lower part (16), which cutting burr penetrates into a lower side (51) of the insulating foil (22) opposite the upper side (27).

9. The temperature-dependent switch according to one of claims 1-7, characterized in that the insulating foil (22) is coated or printed with the sealing agent (26) on one side, namely on its lower side (51) facing the lower part (16), and in that a circumferentially closed cutting burr (52) is provided on the cover part (18), which cutting burr penetrates into an upper side (27) of the insulating foil (22) opposite the lower side (51).

10. The temperature-dependent switch according to one of claims 1-9, characterized in that an edge of the cover part (18) presses or is pressed onto the lower part (16) in the sealing area (29) with the insulating foil (22) interposed there between.

11. The temperature-dependent switch according to one of claims 1-10, characterized in that the lower part (16) comprises a circumferential wall, the upper section (20) of which overlaps the cover part (18), in that a circumferential shoulder (24) is provided in the lower part (16), on which shoulder the cover part (18) rests with the insulating foil (22) interposed there between, wherein the upper section (20) of the lower part (16) presses the cover part (18) onto the circumferential shoulder (24), and that the sealing area is arranged on the circumferential shoulder (24) and / or on a lower edge of the cover part (18) facing the circumferential shoulder (24).

12. A method of manufacturing a temperature-dependent switch (10), comprising the steps of: - providing a lower part (16) of a housing (12); - providing a cover part (18) of the housing (12); - providing a temperature-dependent switching mechanism (14) which, in a mounted state of the switch (10), establishes or opens an electrically conductive connection between a first external contact surface (48) provided externally on the housing (12) and a second contact surface (50) provided externally on the housing (12) as a function of its temperature, - providing an insulating foil (22); - coating or printing the insulating foil (22) with a sealing agent (26); and - mounting the housing (12), wherein the switching mechanism (14) is arranged in the housing (12) and the cover part (18) is mounted on the lower part (16) with the insulating foil (22) interposed there between in such a way that the sealing agent (26) for sealing the housing (12) contacts the cover part (18) and / or the lower part (16) in a sealing area (29), characterized in that the insulating foil (22) is only partially coated or printed with the sealing agent (26) in a sealing region on its upper side (27) facing the cover part (18) and / or on its lower side (51) facing the lower part (16), such that the sealing agent (26) forms a closed contour (31) on the upper side (27) and / or the lower side (51) of the insulating foil (22).

13. The method according to claim 12, wherein the switch (10) is heated to activate the sealing agent (26) after mounting the housing (12).

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