TEMPERATURE-DEPENDENT SWITCH AND METHOD OF MANUFACTURING A TEMPERATURE-DEPENDENT SWITCH

Abstract

A temperature-dependent switch having a first electrode, a second electrode, a temperature-dependent switching mechanism, and a housing that accommodates the switching mechanism. The first electrode is connected to a stationary contact that is arranged inside the housing and the switching mechanism comprises a component that is movable relative to the housing, on which movable component a movable contact member is arranged. The switching mechanism is configured to switch, depending on its temperature, between a closed state of the switch and an open state of the switch. A first terminal member is attached to the first electrode by a first welded joint produced by ultrasonic welding and/or a second terminal member is attached to the second electrode by a second welded joint produced by ultrasonic welding and/or the stationary contact is attached to a part of the first electrode arranged inside the housing by a third welded joint produced by ultrasonic welding and/or the movable contact member is fastened to the movable component by a fourth welded joint produced by ultrasonic welding.

Claims

1. A temperature-dependent switch, comprising: a temperature-dependent switching mechanism; and a housing that accommodates the switching mechanism and comprises an upper part and a lower part that is electrically insulated from the upper part; wherein at least a part of the upper part is made of electrically conductive material and forms a first electrode, wherein at least a part of the lower part is made of electrically conductive material and forms a second electrode, wherein the first electrode is connected to a stationary contact that is arranged inside the housing, and wherein the switching mechanism comprises a component that is movable relative to the housing, on which movable component a movable contact member is arranged, wherein the switching mechanism is configured to switch, depending on its temperature, between a closed state of the switch, in which the movable contact member interacts with the stationary contact and establishes an electrically conductive connection between the first electrode and the second electrode, and an open state of the switch, in which the movable contact member is kept at a distance from the stationary contact and the electrically conductive connection between the first electrode and the second electrode is disconnected, and wherein (i) a first terminal member is attached to the first electrode by a first welded joint produced by ultrasonic welding and/or (ii) a second terminal member is attached to the second electrode by a second welded joint produced by ultrasonic welding.

2. The temperature-dependent switch according to claim 1, (i) wherein the first terminal member comprises a first terminal lug or stranded wire, and/or (ii) wherein the second terminal member comprises a second terminal lug or stranded wire.

3. The temperature-dependent switch according to claim 2, (i) wherein the first terminal lug or stranded wire is attached at its first end to the first electrode by the first welded joint and its second end that is remote from the first end serves as a first terminal; and/or (ii) wherein the second terminal lug or stranded wire is attached at its first end to the second electrode by the second welded joint and its second end that is remote from the first end serves as a second terminal.

4. The temperature-dependent switch according to claim 1, wherein each of the upper part and the lower part is made of electrically conductive material, and wherein an insulating element is arranged between the upper part and the lower part, wherein the insulating element is configured to electrically insulate the upper part from the lower part.

5. The temperature-dependent switch according to claim 1, wherein the stationary contact is attached to a part of the first electrode by a third welded joint produced by ultrasonic welding, said part of the first electrode being arranged inside the housing.

6. The temperature-dependent switch according to claim 1, wherein the movable contact member is attached to the movable component by a fourth welded joint produced by ultrasonic welding.

7. A temperature-dependent switch, comprising: a first electrode; a second electrode; a temperature-dependent switching mechanism; and a housing accommodating the switching mechanism; wherein the first electrode is connected to a stationary contact that is arranged inside the housing, and wherein the switching mechanism comprises a component that is movable relative to the housing, on which movable component a movable contact member is arranged, wherein the switching mechanism is configured to switch, depending on its temperature, between a closed state of the switch, in which the movable contact member interacts with the stationary contact and establishes an electrically conductive connection between the first electrode and the second electrode, and an open state of the switch, in which the movable contact member is kept at a distance from the stationary contact and the electrically conductive connection between the first electrode and the second electrode is disconnected, and wherein (i) the stationary contact is attached to a part of the first electrode by a third welded joint produced by ultrasonic welding, said part of the first electrode being arranged inside the housing and/or (ii) the movable contact member is attached to the movable component by a fourth welded joint produced by ultrasonic welding.

8. The temperature-dependent switch according to claim 7, wherein the temperature-dependent switching mechanism comprises a bi-metal member, wherein the bi-metal member is the movable component on which the movable contact member is arranged.

9. The temperature-dependent switch according to claim 7, wherein the temperature-dependent switching mechanism comprises a bi-metal member and a spring member interacting with the bi-metal member, wherein the spring member is the movable component on which the movable contact member is arranged.

10. The temperature-dependent switch according to claim 9, wherein the bi-metal member comprises a temperature-dependent bi-metal snap disc, and wherein the spring member comprises a bistable spring snap disc.

11. The temperature-dependent switch according to claim 10, wherein the bi-metal member is held captive with clearance on the movable contact member.

12. The temperature-dependent switch according to claim 7, wherein the housing comprises an upper part and a lower part that is electrically insulated from the upper part, wherein the upper part forms the first electrode and the lower part forms the second electrode, and wherein the stationary contact is arranged on an inner side of the upper part facing an interior of the housing.

13. The temperature-dependent switch according to claim 7, wherein the housing comprises an upper part made of insulating material or PTC-material and a lower part, wherein the first electrode and the second electrode are arranged at the upper part.

14. The temperature-dependent switch according to claim 13, wherein the movable component is a contact element coupled to a bi-metal member, on which contact element a second movable contact member is arranged in addition to the movable contact member, and wherein a second stationary contact is attached to a part of the second electrode arranged inside the housing by a fifth welded joint produced by ultrasonic welding.

15. The temperature-dependent switch according to claim 7, wherein at least a part of the housing is made of insulating material or PTC-material, and wherein (i) a first portion of the first electrode extends into an interior of the housing and a second portion of the first electrode extends outward from the interior of the housing and/or (ii) a first portion of the second electrode extends into the interior of the housing and a second portion of the second electrode extends outward from the interior of the housing.

16. A method of manufacturing a temperature-dependent switch, comprising the steps: a) providing a switching mechanism and a housing comprising an upper part and a lower part, wherein at least a part of the upper part is made of electrically conductive material and forms a first electrode, and wherein at least a part of the lower part is made of electrically conductive material and forms a second electrode, b) mounting the switching mechanism in the housing such that the first electrode is connected to a stationary contact that is arranged inside the housing and the switching mechanism comprises a component that is movable relative to the housing, on which movable component a movable contact member is arranged, and such that the switching mechanism is configured to switch, depending on its temperature, between a closed state of the switch, in which the movable contact member interacts with the stationary contact and establishes an electrically conductive connection between the first electrode and the second electrode, and an open state of the switch, in which the movable contact member is kept at a distance from the stationary contact and the electrically conductive connection between the first electrode and the second electrode is disconnected, c) closing the housing by attaching the upper part to the lower part, wherein the upper part is electrically insulated from the lower part; and d1) attaching a first terminal member to the first electrode by a first welded joint produced by ultrasonic welding, and/or d2) attaching a second terminal member to the second electrode by a second welded joint produced by ultrasonic welding.

17. The method according to claim 16, wherein step d1) and/or step d2) is carried out after step c).

18. A method of manufacturing a temperature-dependent switch, comprising the steps: a) providing a first electrode, a second electrode, a temperature-dependent switching mechanism, and a housing; b) mounting the switching mechanism in the housing, such that the first electrode is connected to a stationary contact that is arranged inside the housing and the switching mechanism comprises a component that is movable relative to the housing, on which movable component a movable contact member is arranged, and such that the switching mechanism is configured to switch, depending on its temperature, between a closed state of the switch, in which the movable contact member interacts with the stationary contact and establishes an electrically conductive connection between the first electrode and the second electrode, and an open state of the switch, in which the movable contact member is kept at a distance from the stationary contact and the electrically conductive connection between the first electrode and the second electrode is open, and c1) attaching the stationary contact to a part of the first electrode by a third welded joint produced by ultrasonic welding, said part of the first electrode being arranged inside the housing, and/or c2) attaching the movable contact member to the movable component by a fourth welded joint produced by ultrasonic welding.

19. The method according to claim 18, wherein step c1) and/or step c2) is carried out before the switching mechanism is mounted in the housing in step b).

20. The method according to claim 18, wherein a bi-metal member and a spring member interacting with the bi-metal member are provided as parts of the switching mechanism in step a), wherein the spring member forms the movable component on which the movable contact member is arranged, and wherein the movable contact member is attached to the spring member by the fourth welded joint produced by ultrasonic welding, and thereafter the bi-metal member is captively attached with clearance to the movable contact member before the switching mechanism is mounted in the housing in step b).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0105] FIG. 1 shows a schematic cross-section of a temperature-dependent switch according to a first embodiment;

[0106] FIG. 2 shows a schematic cross-section of a temperature-dependent switch according to a second embodiment;

[0107] FIG. 3 shows a schematic cross-section of a temperature-dependent switch according to a third embodiment; and

[0108] FIG. 4 shows a schematic cross-section of a temperature-dependent switch according to a fourth embodiment.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0109] FIG. 1 shows a first embodiment of the temperature-dependent switch in a schematic cross-sectional view. The switch is denoted in its entirety with the reference numeral 10.

[0110] The switch 10 comprises a housing 12 and a temperature-dependent switching mechanism 14 accommodated therein. The housing 12 includes an upper part 16 made of electrically conductive material and a lower part 18 made of electrically conductive material.

[0111] Between the upper part 16 and the lower part 18 there is an insulating foil 20, which electrically isolates the upper part 16 from the lower part 18.

[0112] In this embodiment, the upper part 16 and the lower part 18 form the two electrodes 22, 24 of the switch 10. The two electrodes 22, 24 serve as contact points at which external terminals can be arranged to connect the switch 10 to a device to be protected. However, depending on the application, the two electrodes 22, 24 of the switch 10 can also be connected directly to the device to be protected.

[0113] For better differentiation, the electrode 22 formed by the upper part 16 is referred to below as first electrode and the electrode 24 formed by the lower part 18 is referred to as second electrode.

[0114] A stationary contact 28 is attached to an inner side 26 of the upper part 16 facing the inside of the housing 12, which comprises a contact surface 30 facing the lower part 18.

[0115] The stationary contact 28 is preferably attached to the inner side 26 of the upper part 16 by a welded joint produced by ultrasonic welding, wherein the inner side 26 forms the first electrode 22. The stationary contact 28 is thus electrically connected to the upper part 16, so that an upper side 32 of the upper part 16 facing away from the inside of the housing is available as the first external terminal of the switch.

[0116] The lower part 18, which functions as a second electrode 24, comprises a second contact surface 36 on its inside 34. Since the lower part 18 is also electrically conductive, its outer or lower side 38 serves as the second external terminal of switch 10.

[0117] Contact to the first electrode 22 is made via a first terminal member 31, which is attached to the upper part 16 by a welded joint produced by ultrasonic welding. The first terminal member 31 is configured as a terminal lug 51 in the embodiment shown in FIG. 1, wherein the terminal lug 51 is of annular shape at one end 35. With this annular end 35, the terminal lug 51 is supported on an outer, circumferential shoulder 37 of the upper part 16, which is set back in relation to the upper side 32. The extent of the recess of the shoulder 37 and the thickness of the terminal lug 51 are such that the terminal lug 51 does not project upwards beyond the upper part 16 in the region of its annular first end 35. In this way a low overall height is made possible.

[0118] In a similar way, in the embodiment shown in FIG. 1, contact to the second electrode 24 is made by a second terminal member 33, which is also configured as a terminal lug 53, which is attached to the lower part 18 by a welded joint produced by means of ultrasonic welding. The terminal lug 53 is of annular shape at its first end 39. With this annular end 39, the terminal lug 53 is supported on an outer circumferential shoulder 43 of the lower part 18, which is set back in relation to the underside 38. The extent of the recess of the shoulder 43 and the thickness of the terminal lug 53 are also selected so that the terminal lug 53 does not project downwards beyond the lower part 18 in the region of its annular first end 39. In addition to the resulting low overall height of the switch 10, this has the advantage that the lower part 18 can, if desired, be supported directly on the device to be monitored, which ensures good heat transfer.

[0119] Furthermore, FIG. 1 shows that the two terminal lugs 51, 53 are angled in such a way that their two second ends 47, 49, which are remote from the first ends 35, 39, are set back from the shoulders 37, 43 of housing 12. These second ends 47, 49 of the terminal lugs 51, 53 serve as terminals of the switch 10. For example, a stranded wire not visible in FIG. 1 may be attached to each of the two second ends 47, 49 of the terminal lugs 51, 53.

[0120] Depending on its temperature, the switching mechanism 14 located in the housing 12 establishes an electrically conductive connection between the upper part 16 and the lower part 18 and disconnects this electrically conductive connection abruptly when a response temperature or transition temperature is exceeded.

[0121] The switching mechanism 14 comprises a movable contact member 40 which is attached to a component 42 which is movable relative to the housing 12. In this embodiment, the movable component 42 of the switching mechanism 14 is a spring member 44 which is integrally connected to a lateral connecting bar which is attached at a point marked 48 to the second contact surface 36 provided on the lower part 18.

[0122] The spring member 44 is configured as a slightly domed spring snap disc, which centrally supports the movable contact member 40. The movable contact member 40 is attached to the spring snap disc 44 by a welded joint produced by ultrasonic welding. The lateral connection between the spring snap disc 44 and the contact surface 36 arranged on the lower part 18 is preferably also produced by ultrasonic welding.

[0123] A bi-metal member 52 with a central opening 50 sits on the movable contact member 40 with clearance but captive. In the state shown in FIG. 1, the bi-metal member 52 is in its low-temperature position in which it rests in a force-free manner on the spring snap disc 44. The bi-metal member 52 is designed as a bi-metal snap disc.

[0124] The movable contact member 40 has a dome-shaped tip 54, which, is, in the closed state of the switch 10 shown in FIG. 1, in contact with the stationary contact 28 or its contact surface 30. Below the dome-shaped tip 54, a flange 56 is provided on the movable contact member 40, to the lower end of which a cylindrical extension 58 is attached. As can be seen from FIG. 1, the flange 56 of the movable contact member 40 has a larger diameter than the central opening 50 provided in the bi-metal snap disc 52. The cylindrical projection 58, which extends through the central opening 50 of the bi-metal snap disc 52, has a smaller diameter than the central opening 50. This ensures that the bi-metal snap disc 52 is held captive but with clearance on the movable contact member 40.

[0125] When manufacturing the switching mechanism 14, the movable contact member 40 is first welded onto the spring snap disc 44 with the underside of the cylindrical extension 58. This welded joint is made by means of ultrasonic welding. Since ultrasonic welding generates considerably less heat between the two components to be joined than the fusion welding methods conventionally used, the spring snap disc 44 is hardly stressed. This is particularly advantageous because the spring snap disc 44 is usually a very thin-walled component with a thickness of only a few millimeters or even less. In addition, ultrasonic welding does not require any filler materials that are harmful to the environment. Nevertheless, the welded joint produced by ultrasonic welding creates a mechanically extremely stable and electrically highly conductive connection between the movable contact member 40 and the spring snap disc 44.

[0126] After producing the welded joint between the movable contact member 40 and the spring snap disc 44, the bi-metal snap disc 52 is placed from above with its central opening over the movable contact member 40. During this process, the flange 56 still has a smaller diameter than the central opening 50, as it is not yet spread or expanded laterally as shown in FIG. 1. The flange 56 of the movable contact member 40 is only expanded or widened after the bi-metal snap disc 52 has been inserted or turned over, which can be done by pressing, for example. The bi-metal snap disc 52 is then held captive, but with clearance, on the movable contact member 40, which in turn is connected to the spring snap disc 44.

[0127] The switching mechanism 14 manufactured in this way can then be inserted into the housing 12 as an already assembled semi-finished component and, as already mentioned, attached in the housing 12 by welding the spring snap disc 44 to the lower part 18. Since the welded joint between the movable contact member and the spring member 44 is produced by ultrasonic welding before the bi-metal snap disc 52 is placed over the contact member 40, the bi-metal snap disc 52 is not affected in any way by the welding process mentioned above. The welding process between the spring snap disc 44 and the lower part 18 also has no influence on the bi-metal snap disc 52, as the latter is held with clearance on the movable contact member 40 and therefore no direct heat transfer by heat conduction to the bi-metal snap disc 52 takes place. This has a positive effect on the functioning and service life of the bi-metal snap disc 52.

[0128] Due to the permanent mechanical and galvanic connection between the spring snap disc 44 and the lower part 18, there is a very low contact resistance between the lower part 18, acting as second electrode 24, and the spring snap disc 44.

[0129] Since the movable contact member 40 is welded to the spring snap disc 44 in the above mentioned manner, the contact resistance between the spring snap disc 44 and the movable contact member 40 is also extremely low.

[0130] By selecting a suitable surface finish of the dome-shaped tip 54 of the contact member 40 and the first contact surface 30 of the stationary contact 28, the contact resistance is also very low there.

[0131] The ultrasonic welded joint produced between the stationary contact 28 and the upper part 16 also results in a very low contact resistance between these two components.

[0132] The upper part 16 and the lower part 18 can therefore be designed as inexpensive deep-drawn parts, because the quality of the contact resistances is provided by the described welded joints.

[0133] In this way, the entire switch 10 has only a very low contact resistance between the first electrode 22 and the second electrode 24, so that it is virtually a galvanic short circuit.

[0134] If, starting from the closed state of the switch 10 shown in FIG. 1, its temperature now increases above the transition temperature of the bi-metal snap disc 52, the latter moves downwards in FIG. 1 with its still free edge 60 in FIG. 1 until this edge 60 comes into contact with the insulating foil 20 where it is located below an annular rim 62 of the upper part 16.

[0135] In doing so, the bi-metal snap disc 52 presses with its central area 64 centrally on the spring snap disc 44 and pushes it downwards as shown in FIG. 1, lifting the movable contact member 40 from the stationary contact 28, so that the switch 10 opens.

[0136] When the ambient temperature and thus the temperature of the bi-metal snap disc 52 cools down again below the transition temperature, the bi-metal snap disc 52 returns to its low-temperature position shown in FIG. 1, causing the opening pressure on the spring snap disc 44 to decrease. Due to the internal forces, the spring snap disc 44 then resets to its rest position shown in FIG. 1, in which it is clamped between the inside 34 of the lower part 18 and the stationary contact 28, thus ensuring an attached contact pressure and a securely closed switch 10.

[0137] FIG. 2 shows a second embodiment of a temperature-dependent switch, which in its entirety is also denoted with the reference numeral 10. Components which correspond to the components of the switch according to the first embodiment shown in FIG. 1 are marked with the same reference number in FIG. 2. For the sake of simplicity, only the essential differences to the first embodiment shown in FIG. 1 are described below.

[0138] The housing 12 of the switch 10 shown in FIG. 2 includes an electrically conductive, pot-like lower part 18, which is closed by an electrically conductive upper part 16, which is configured here as a cover part. The upper part 16 is held on the lower part 18 by a flanged edge 66 with an interposed insulating foil 20.

[0139] The upper part 16 and the lower part 18 also in this case form the two electrodes 22, 24 of switch 10, and accordingly the upper side 32 of the upper part 16 serves as the first connection surface, and the outer side 38 of the lower part 18 serves as the second connection surface. Supply lines can be attached to these two connection surfaces by means of stranded wires or terminal lugs in order to connect switch 10 to a device to be protected.

[0140] Similar to the first embodiment, the second terminal member 33 is configured as a terminal lug 53, the annular first end 39 of which is attached to the shoulder 43 surrounding the lower part 18 by a welded joint produced by ultrasonic welding. The first terminal member 31a is configured here, however, as a stranded wire 55, which is attached with its stripped first end 35a to the upper side 32 of the upper part 16 by a welded joint produced by means of ultrasonic welding. It goes without saying that in principle the second terminal member 33 may also be configured as a stranded wire, which is attached to the underside 38 of the lower part 18 by a welded joint produced by means of ultrasonic welding. In the same way it is also possible with the switch design shown in FIG. 2 to use a terminal lug 51 as shown in FIG. 1 for the first terminal member 31a.

[0141] The stationary contact 28 is, similar to the first embodiment, preferably attached to the inner or lower side 26 of the upper part 16 by a welded joint produced by ultrasonic welding.

[0142] In contrast to the first embodiment shown in FIG. 1, the switch 10 shown in FIG. 2 does not comprise a spring snap disc 44. Instead, the bi-metal snap disc 52 functions as movable component 42, to which the movable contact member 40 is attached. The bi-metal snap disc 52 takes over the function of the spring snap disc 44 in the example of switch 10 shown in FIG. 2.

[0143] The bi-metal snap disc 52 is clamped in the housing 12 in such a way that in its low-temperature position, as shown in FIG. 2, it rests on and contacts the inner side 34 of the lower part 18. In principle, however, the bi-metal member 52 may also be designed as a bi-metal spring clamped on one side, which is connected at a contact member to the inside 34 of the lower part 18 by means of a material bond.

[0144] Additionally, it is to be understood that with the same construction of the housing 12, the switching mechanism 14 may also have a spring snap disc 44 according to this embodiment, so that a similar construction of the switching mechanism 14 as shown in FIG. 1 then results.

[0145] In the embodiment shown in FIG. 2, the movable contact member 40 also has a dome-shaped tip 54, at the lower end of which there is in this case a widened socket 70, the underside of which is attached to the bi-metal snap disc 52. This attachment is realized by a welded joint produced by ultrasonic welding. In addition to the above-mentioned advantages of ultrasonic welding, another advantage is that a welded joint produced by ultrasonic welding at this point protects the very sensitive and typically thin-walled bi-metal snap disc 52. A hot welding process used at this point to connect the movable contact member 40 with the bi-metal snap disc 52 could damage the bi-metal snap disc 52 to such an extent that its function is permanently impaired.

[0146] With regard to the embodiment shown in FIG. 2, it should also be mentioned that the upper part 16 does not necessarily have to be made of electrically conductive material. It can also be made of insulating material or Positive Temperature Coefficient (PTC) ceramics. In such a case, the first connection surface of the switch 10 is formed by a metal layer arranged on the upper side 32, which metal layer is plated through the upper part 16 to the stationary contact 28. Therefore, in this case only a part of the upper part 16 would be made of electrically conductive material (metal layer). This metal layer then forms the first electrode 22 of switch 10, so that a corresponding lead can be attached to it, for example by means of a stranded wire or a terminal lug. According to the terminology used herein, the first electrode 22 of switch 10 would then not be formed by the entire upper part 16, but only by a part of it or would be located on it.

[0147] FIG. 3 shows a third embodiment of the temperature-dependent switch 10. Components which correspond to the components shown in FIGS. 1 and 2 are for the sake of simplicity again denoted here with the same reference numerals as before.

[0148] An essential difference to the two embodiments shown above is that both terminal electrodes 22, 24 of the switch 10 are arranged at the upper part 16. Accordingly, the construction of the housing 12 as well as the construction of the switching mechanism 14 differs in some features, which will be explained in the following in detail.

[0149] The housing 12 comprises a plate-like lower part 18, on the raised edge 72 of which an external circumferential groove 74 is provided. The upper part 16, which is in this case essentially cup-shaped, is supported on the raised edge 72 by an inner shoulder 76. An edge 78 projects over the shoulder 76, on which an inner circumferential bead 80 is provided, which engages with the groove 74, whereby the lower part 18 is locked with the upper part 16. The edge 78 merges into a ring-shaped overlap 82, by means of which the lower part 18 is held further on the upper part 16.

[0150] This overlap 82 can be created by embossing or welding a projecting area of the edge 78.

[0151] While the upper part 16 is made of insulating material, the lower part 18 can also be made of insulating material or of metal, wherein a lower part 18 made of metal provides a better thermal connection of the switch 10 to a device to be protected.

[0152] The two electrodes 22, 24, which are located next to each other, are cast into the upper part 16, each of which carries a stationary contact 28, 29. In contrast to the two embodiments mentioned above, the switch, according to the embodiment shown in FIG. 3, therefore, comprises not only one stationary contact 28 but also a second stationary contact 29. The two stationary contacts 28, 29 are each attached to the first and second electrode 22, 24, respectively, by a welded joint produced by ultrasonic welding. This welded joint produced by ultrasonic welding provides similar advantages as described above with regard to the connection of the stationary contact 28 with the upper part 16 forming the first electrode 22.

[0153] A movable contact member 84 in the form of a movable contact bridge is assigned to the two stationary contacts 28, 29. In this example, this movable contact member 84 functions as movable component 42 of the switching mechanism 14, on which a first and a second contact member 40, 41 are arranged. The two movable contact members 40, 41 are preferably integrally connected to each other.

[0154] The movable contact member 84, configured as a contact bridge, is mechanically coupled with the spring snap disc 44 and the bi-metal snap disc 52 via a rivet 86. The bi-metal snap disc 52 is supported with its edge 68 in the closed state of the switch 10 shown in FIG. 3 on the inside 34 of the lower part 18. The edge 45 of the spring snap disc 44 is circumferentially guided in a circumferential groove 88, which is formed between the shoulder 76 of the upper part 16 and the edge 72 of the lower part 18.

[0155] Depending on the temperature, the switching mechanism 14 brings the contact member 84 coupled with the bi-metal snap disc 52 into contact with the two stationary contacts 28, 29 or lifts the contact member 84 from the two stationary contacts 28, 29.

[0156] Additionally, the two openings 90, 92 in FIG. 3 should be mentioned, which are located on the upper sides of electrodes 22, 24 facing away from the stationary contacts 28, 29. These openings 90, 92, which lead outwards, serve on the one hand for a thermal coupling of the switch 10 to a device to be protected and on the other hand may be provided for test purposes, namely to heat up the inside of the switch 10 as quickly as possible by means of heating stamps and/or to contact the two stationary contacts 28, 29 from the outside by means of test pins in order to test the function of the switch 10.

[0157] FIG. 4 shows a fourth embodiment in a schematic cross-sectional view. The basic construction of the switch shown therein is similar to switch 10 shown in FIG. 1.

[0158] Here, too, the switching mechanism 14 comprises a bi-metal snap disc 52 and a spring snap disc 44 coupled to it. The spring snap disc 44 again forms the movable component 42, to which the movable contact member 40 is attached.

[0159] The housing 12 consists of one or more parts and is at least partially made of insulating material or PTC-material. Although this is not explicitly shown in FIG. 4, the housing 12 may comprise one or more openings which improve the thermal connection of switch 10 to the device to be protected.

[0160] In contrast to the embodiments shown above, the two electrodes 22, 24 are here designed as connection plates which are passed through a side wall 94 of housing 12. A first part 96 of the first electrode 22 protrudes into the interior of the housing 12 and a second part 97 of the first electrode 22 is led through the side wall 94 from the interior of the housing 12 to the outside. Likewise, a first part 98 of the second electrode 24 projects into the interior of the housing 12 and a second part 99 of the second electrode 24 is led out of the interior of the housing 12. Preferably, the first two parts 96, 98 of the electrodes 22, 24 rest against an inner side of the housing 12 or are clamped in the housing 12. In principle, however, it would also be possible for these two parts 96, 98 of the electrodes 22, 24 to be arranged freely suspended inside the housing 12 and to be clamped on one side only at the point where they pass through the housing wall 94.

[0161] The stationary contact 28 is attached to the first part 96 of the first electrode 22 by means of a welded joint produced by ultrasonic welding. The movable contact member 40 is attached to the spring snap disc 44 by means of a welded joint produced by ultrasonic welding. In the low temperature position of switch 10 shown in FIG. 4, the bottom or outer edge of the spring snap disc 44 rests on the first part 98 of the second electrode 24, so that an electrical connection is established.

[0162] It is to be understood that the foregoing is a description of one or more preferred exemplary embodiments of the invention. The invention is not limited to the particular embodiment(s) disclosed herein, but rather is defined solely by the claims below. Furthermore, the statements contained in the foregoing description relate to particular embodiments and are not to be construed as limitations on the scope of the invention or on the definition of terms used in the claims, except where a term or phrase is expressly defined above. Various other embodiments and various changes and modifications to the disclosed embodiment(s) will become apparent to those skilled in the art. All such other embodiments, changes, and modifications are intended to come within the scope of the appended claims.

[0163] As used in this specification and claims, the terms for example, e.g., for instance, such as, and like, and the verbs comprising, having, including, and their other verb forms, when used in conjunction with a listing of one or more components or other items, are each to be construed as open-ended, meaning that the listing is not to be considered as excluding other, additional components or items. Other terms are to be construed using their broadest reasonable meaning unless they are used in a context that requires a different interpretation.