Temperature-dependent switch

Abstract

A temperature-dependent switch comprises a first stationary contact, a second stationary contact, and a temperature-dependent switching mechanism having a movable contact member. In its first switching position, the switching mechanism presses the contact member against the first contact and thereby produces an electrically conductive connection between the two contacts. In its second switching position, the switching mechanism keeps the contact member spaced apart from the first contact. The temperature-dependent switching mechanism further comprises first and second temperature-dependent snap-action parts which switch from geometric low-temperature configurations to geometric high-temperature configurations when exceeding first and second switching temperatures, respectively, and switch back when subsequently falling below first and second reset temperatures, respectively. Switching the first and/or the second snap-action part from its geometric low-temperature configuration to its geometric high-temperature configuration brings the switching mechanism from its first switching position to its second switching position.

Claims

1. A temperature-dependent switch that comprises a first stationary contact, a second stationary contact, and a temperature-dependent switching mechanism having a movable contact member, wherein the switching mechanism, in a first switching position, presses the movable contact member against the first stationary contact and thereby produces an electrically conductive connection between the first stationary contact and the second stationary contact via the movable contact member and, in a second switching position, keeps the movable contact member spaced apart from the first stationary contact, wherein the switching mechanism comprises a first temperature-dependent snap-action part which is configured to switch from a first geometric low-temperature configuration to a first geometric high-temperature configuration when exceeding a first switching temperature, and to switch from the first geometric high-temperature configuration back to the first geometric low-temperature configuration when subsequently falling below a first reset temperature, wherein the switch further comprises a second temperature-dependent snap-action part which is configured to switch from a second geometric low-temperature configuration to a second geometric high-temperature configuration when exceeding a second switching temperature that is equal to or higher than the first switching temperature, and to switch from the second geometric high-temperature configuration back to the second geometric low-temperature configuration when subsequently falling below a second reset temperature, wherein switching the first temperature-dependent snap-action part from the first geometric low-temperature configuration to the first geometric high-temperature configuration and/or switching the second temperature-dependent snap-action part from the second geometric low-temperature configuration to the second geometric high-temperature configuration brings the switching mechanism from the first switching position to the second switching position, wherein the second reset temperature is lower than the first reset temperature, wherein the second temperature-dependent snap-action part is configured to keep the movable contact member spaced apart from the first stationary contact even if the switch has heated above the first switching temperature and the second switching temperature and has subsequently cooled down to a temperature between the first reset temperature and the second reset temperature, and wherein the second temperature-dependent snap-action part is configured to bring the switching mechanism from the second switching position back to the first switching position when the switch has heated above the first switching temperature and the second switching temperature and has subsequently cooled down to a temperature equal to or lower than the second reset temperature.

2. The switch according to claim 1, wherein the second reset temperature is lower than room temperature.

3. The switch according to claim 1, wherein the second reset temperature is lower than 15° C.

4. The switch according to claim 1, wherein the switching mechanism comprises a temperature-independent spring part that is connected to the movable contact member, wherein the first temperature-dependent snap-action part is configured to act on the spring part when exceeding the first switching temperature and to thereby lift off the movable contact member from the first stationary contact.

5. The switch according to claim 4, wherein the second snap-action part is in the second geometric high-temperature configuration configured to exert an opening force on the movable contact member so as to keep the movable contact member spaced apart from the first stationary contact, and wherein the first snap-action part is in the first geometric low-temperature configuration configured to exert a closing force together with the spring part on the movable contact member, wherein the closing force is oppositely arranged to the opening force and smaller in magnitude than the opening force.

6. The switch according to claim 4, wherein the spring part comprises a bistable spring part having two temperature-independent, stable geometric configurations.

7. The switch according to claim 1, wherein the first temperature-dependent snap-action part comprises a first bimetal or trimetal snap-action disc.

8. The switch according to claim 1, wherein the second snap-action part comprises a second temperature-dependent bimetal or trimetal snap-action disc.

9. The switch according to claim 1, wherein the movable contact member comprises a first component and a second component that is connected to the first component by means of a non-positive, firmly bonded or positive connection, wherein the first temperature-dependent snap-action part contacts the first component and the second temperature-dependent snap-action part contacts the second component.

10. The switch according to claim 1, wherein the switch comprises a housing, wherein the first stationary contact and the second stationary contact are provided on the housing and the switching mechanism is arranged in the housing.

11. The switch according to claim 10, wherein the housing comprises a lower part and an upper part, wherein the first stationary contact is arranged on an inner side of the upper part.

12. The switch according to claim 10, wherein the housing comprises a lower part and an upper part, wherein the first stationary contact and the second stationary contact are arranged on an inner side of the upper part.

13. The switch according to claim 10, wherein the first temperature-dependent snap-action part is fixed to the movable contact member at a center of the first temperature-dependent snap-action part.

14. The switch according to claim 1, wherein a disc-shaped, plate-shaped or annular support element is arranged locally between the first temperature-dependent snap-action part and the second temperature-dependent snap-action part, wherein the support element comprises a hole through which the movable contact member projects, wherein the second temperature-dependent snap-action part is at least in the second geometric high-temperature configuration supported by the support element.

15. The switch according to claim 14, wherein the switch comprises a housing having an upper part and a lower part, wherein the first temperature-dependent snap-action part is arranged locally between the upper part and the support element, and wherein the second temperature-dependent snap-action part is arranged locally between the support element and the lower part.

16. The switch according to claim 1, wherein the switching mechanism comprises a temperature-independent spring part that is connected to the movable contact member, wherein the movable contact member comprises a movable contact part that interacts with the first stationary contact, and wherein the spring part interacts with the second stationary contact.

17. The switch according to claim 1, wherein the movable contact member comprises a current transfer member that interacts with the first stationary contact and the second stationary contact.

18. A temperature-dependent switch that comprises a first stationary contact, a second stationary contact, and a temperature-dependent switching mechanism having a movable contact member, wherein the switching mechanism, in a first switching position, presses the movable contact member against the first stationary contact and thereby produces an electrically conductive connection between the first stationary contact and the second stationary contact via the movable contact member and, in a second switching position, keeps the movable contact member spaced apart from the first stationary contact, wherein the switching mechanism comprises a first temperature-dependent snap-action part which is fixed to the movable contact member at a center of the first temperature-dependent snap-action part and configured to switch from a first geometric low-temperature configuration to a first geometric high-temperature configuration when exceeding a first switching temperature, and to switch from the first geometric high-temperature configuration back to the first geometric low-temperature configuration when subsequently falling below a first reset temperature, wherein the switch further comprises a second temperature-dependent snap-action part which is configured to switch from a second geometric low-temperature configuration to a second geometric high-temperature configuration when exceeding a second switching temperature, and to switch from the second geometric high-temperature configuration back to the second geometric low-temperature configuration when subsequently falling below a second reset temperature, wherein switching the first temperature-dependent snap-action part from the first geometric low-temperature configuration to the first geometric high-temperature configuration and/or switching the second temperature-dependent snap-action part from the second geometric low-temperature configuration to the second geometric high-temperature configuration brings the switching mechanism from the first switching position to the second switching position, wherein the second reset temperature is lower than the first reset temperature, wherein the second temperature-dependent snap-action part is configured to keep the movable contact member spaced apart from the first stationary contact even if the switch has heated above the first switching temperature and the second switching temperature and has subsequently cooled down to a temperature between the first reset temperature and the second reset temperature, and wherein the second temperature-dependent snap-action part is configured to bring the switching mechanism from the second switching position back to the first switching position when the switch has heated above the first switching temperature and the second switching temperature and has subsequently cooled down to a temperature equal to or lower than the second reset temperature.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 shows a schematic sectional view of a first embodiment of the switch in a first switching position;

(2) FIG. 2 shows a schematic sectional view of the first embodiment of the switch in a second switching position;

(3) FIG. 3 shows a schematic sectional view of the first embodiment of the switch in a third switching position;

(4) FIG. 4 shows a schematic sectional view of the first embodiment of the switch in a fourth switching position;

(5) FIG. 5 shows a schematic sectional view of a second embodiment of the switch in a first switching position; and

(6) FIG. 6 shows a schematic sectional view of the second embodiment of the switch in a second switching position;

(7) FIG. 7 shows a schematic sectional view of the second embodiment of the switch in a third switching position;

(8) FIG. 8 shows a schematic sectional view of the second embodiment of the switch in a fourth switching position; and

(9) FIG. 9 shows a schematic sectional view of a third embodiment of the switch in a first switching position.

DESCRIPTION OF PREFERRED EMBODIMENTS

(10) FIG. 1 shows a schematic, sectional view of a switch 10, which is rotationally symmetrical in top view and preferably has a circular shape.

(11) The switch 10 comprises a housing 12, in which a temperature-dependent switching mechanism 14 is arranged. The housing 12 includes a pot-shaped lower part 16 and an upper part 18, which is held to the lower part 16 by a bent or flanged edge 20.

(12) In the first embodiment shown in FIG. 1, both the lower part 16 and the upper part 18 are made of an electrically conductive material, preferably metal. The upper part 18 rests on a shoulder 24 inside the lower part 16, with an interposed insulating foil 22.

(13) The insulating foil 22 provides an electrical insulation of the upper part 18 against the lower part 16. In addition, the insulating foil 22 also provides a mechanical seal that prevents liquids or contaminants from entering the interior of the housing from the outside.

(14) Since the lower part 16 and the upper part 18 are in this embodiment each made of electrically conductive material, thermal contact to an electrical device to be protected can be produced via their outer surfaces. The outer surfaces are also used for the external electrical connection of the switch 10.

(15) Another insulation layer 26 can be applied to the outside of the upper part 18, as shown in FIG. 1.

(16) The switching mechanism 14 comprises a temperature-independent spring part 28, which is configured as a spring disc, and a temperature-dependent snap-action part 30, which is configured as a snap-action disc.

(17) The spring part 28 is preferably configured as a bistable spring disc. Accordingly, the spring disc 28 has two temperature-independent stable geometric configurations. The first geometrical configuration is shown in FIG. 1.

(18) The temperature-dependent snap-action part 30, which is herein referred to as the first snap-action part 30, is configured as a bistable snap-action disc, for example. The snap-action disc 30 has two temperature-dependent configurations, a geometrical high-temperature configuration and a geometrical low-temperature configuration. In the first switching position of the switching mechanism 14 shown in FIG. 1, the first snap-action disc 30 is in its low-temperature configuration.

(19) The spring disc 28 rests with its edge 32 on an inner bottom surface 34 of the lower part 16. The inner bottom surface 34 is substantially concave in shape and is slightly raised at the point where the edge 32 of the spring disc 28 rests in the first switching position shown in FIG. 1 compared to the central area of the inner bottom surface 34. The edge 36 of the first snap-action disc 30 rests on the spring disc 28 in its low-temperature configuration shown in FIG. 1.

(20) The spring disc 28 is with its center 38 fixed to a movable contact member 40 of the switching mechanism 14. The first snap-action disc 30 is with its center 42 also fixed to this contact member 40. In this way, the temperature-dependent switching mechanism 14 is a captive unit consisting of contact member 40, spring disc 28 and first snap-action disc 30. When mounting the switch 10, the switching mechanism 14 can thus be inserted as a unit directly into the lower part 16.

(21) A second snap-action part 44 is arranged above the first snap-action disc 30 in the embodiment shown in FIG. 1. Similar to the first snap-action disc 30, this second snap-action disc 44 is preferably configured as a temperature-dependent, bistable snap-action disc. This second snap-action disc 44 also preferably has two configurations, a geometrical high-temperature configuration and a geometrical low-temperature configuration. In the first switching position of the switching mechanism 14 shown in FIG. 1, the second snap-action disc 44 is in its geometrical low-temperature configuration.

(22) In the example shown in FIG. 1, the second snap-action disc 44 preferably rests on the first snap-action disc 30. The second snap-action disc 44 is not firmly connected to the first snap-action disc 30. In the first embodiment shown in FIG. 1, the second snap-action disc 44 is also not firmly connected to the movable contact member 40. In the low-temperature configuration shown in FIG. 1, it is only supported by the switching mechanism 14 or rests on it from above.

(23) Since the second snap-action disc 44 has a decisive influence on the switching behavior of switch 10 just like the first snap-action disc 30, the second snap-action disc 44 can basically be regarded as part of the switching mechanism 14. However, depending on the definition, the second snap-action disc 44 can also be considered as a separate component.

(24) On its upper side, the movable contact member 40 comprises a movable contact part 46. The movable contact part 46 interacts with a fixed counter contact 48, which is located on an inner side of the upper part 18. This counter contact 48 is herein also referred to as the first stationary contact. The outside of the lower part 16 of the switch 10 shown in FIG. 1 serves as the second stationary contact 50.

(25) In the position shown in FIG. 1, the switch 10 is in its low-temperature position (first switching position), in which the spring disc 28 is in its first configuration and the two snap-action discs 30, 44 are in their respective low-temperature configuration. In the low-temperature position of the switch 10 according to FIG. 1, an electrically conductive connection between the first stationary contact 48 and the second stationary contact 50 is produced via the movable contact member 42 and the spring disc 30.

(26) If the temperature of the device to be protected, and thus the temperature of the switch 10 and the first snap-action disc located therein, increases, the first snap-action disc switches from the low-temperature configuration shown in FIG. 1 to its concave high-temperature configuration shown in FIG. 2.

(27) When switching, the first snap-action disc 30 is with its edge 36 supported by the second snap-action disc 44, wherein the second snap-action disc 44 is clamped between the first snap-action disc 30 and the upper part 18 or the insulating foil 22. With its center 42, the first snap-action disc 30 pulls the movable contact member 40 downwards and lifts off the movable contact member 46 from the first stationary contact 48. This simultaneously bends the spring disc 28 at its center 38 downward so that the spring disc 28 snaps from its first stable geometric configuration shown in FIG. 1 to its second stable geometric configuration shown in FIG. 2. The electric circuit is thus disconnected.

(28) The switching operation, which moves the switch 10 from its closed position shown in FIG. 1 to its open position shown in FIG. 2, occurs upon reaching or exceeding the switching temperature of the first snap-action disc 30. This switching temperature is herein referred to as first switching temperature.

(29) On the other hand, the second snap-action disc 44 is designed in such a way that its switching temperature, at which it switches from its geometrical low-temperature configuration to its geometrical high-temperature configuration, is slightly higher than the first switching temperature. The switching temperature of the second snap-action disc 44 is herein referred to as second switching temperature.

(30) FIG. 2 thus shows the switch 10 in its second switching position, in which the first switching temperature has been reached or exceeded, but the second switching temperature has not yet been reached.

(31) In the second switching position of the switch 10 shown in FIG. 2, the second snap-action disc 44 is therefore still in its geometrical low-temperature configuration as it is also shown in FIG. 1. However, since the second snap-action disc 44 is not firmly connected to the movable contact member 40, the second snap-action disc 44 in this position does not exert any force on the movable contact member 40 which would counteract the force exerted by the spring disc 28 and the first snap-action disc 30 on the movable contact member 40. Upon reaching the first switching temperature, the switch 10 is thus in any case open.

(32) If the temperature of the switch 10 and thus also the temperature of the second snap-action disc 44 increases further beyond the second switching temperature after reaching the switching position shown in FIG. 2, the second snap-action disc 44 also switches from its convex low-temperature position shown in FIG. 2 to the concave high-temperature position shown in FIG. 3. It then rests with its edge 52 on the upper part 18 or on the insulating foil 22 arranged below it and presses with its center 54 on the first snap-action disc 30. As a result, the second snap-action disc 44 also exerts a force on the movable contact member 40 which keeps the movable contact member 46 spaced apart from the first stationary contact 48.

(33) Such a further increase in temperature despite the switch 10 already being open is quite common in practice due to the residual heat of the electrical device to be protected. This is typically referred to as the overshoot temperature or the overshoot temperature range of the switch 10.

(34) The switching temperature of the second snap-action disc 44 is preferably located at this overshoot temperature or in this overshoot temperature range and thus preferably only slightly higher than the first switching temperature of the first snap-action disc 30.

(35) However, it is also generally possible to design the second snap-action disc 44 in such a way that it switches from its geometrical low-temperature configuration to its geometrical high-temperature configuration concurrently with the first snap-action disc 30. In this case, the second switching temperature would thus correspond to the first switching temperature. The function of the switch 10 would remain basically the same, since it would also be opened then upon reaching the first switching temperature. In this case, however, it would go directly from the first switching position shown in FIG. 1 to the third switching position shown in FIG. 3, in which both snap-action discs 30, 44 have snapped over to their high-temperature configuration.

(36) In principle, it would even be possible that the second switching temperature is lower than the first switching temperature, so that upon heating the switch 10 the second snap-action disc 44 switches to its high-temperature configuration and opens the switch before the first snap-action disc. However, this would require that the force exerted by the second snap-action disc 44 in its high-temperature configuration on the movable contact member 40 is greater than the force exerted by the first snap-action disc 30 in its low-temperature configuration and the spring disc 28 in its first configuration on the movable contact member 40 together.

(37) However, it is generally preferred that the first snap-action disc 30 is responsible for opening the switch 10, i.e. that the first switching temperature is lower than the second switching temperature or at least equal to the second switching temperature.

(38) Since the electric circuit of the electrical device to be protected is disconnected, the switch 10 now cools down again. As soon as the switch 10 has cooled down to or below the reset temperature of the first snap-action disc 30 (first reset temperature), the snap-action disc 30 switches from its high-temperature position shown in FIG. 3 back to its low-temperature position and thereby pulls the spring disc 28 upwards again in the direction of its first configuration. Since the reset temperature of the second snap-action disc 44 (second reset temperature) is lower than the first reset temperature, the second snap-action disc 44 will still remain in its high-temperature configuration upon reaching the first reset temperature. This results in the fourth switching position shown in FIG. 4, in which the movable contact part 46 remains spaced apart from the first stationary contact 48 and the switch 10 is thus still open.

(39) In this case, the second snap-action disc 44 exerts a greater spring force on the movable contact member 40 than the first snap-action disc 30 and the spring disk 28 together, which actually try to move the movable contact member 46 towards the first stationary contact 48. According to this first embodiment of the switch 10, the second snap-action disc 44 has a higher spring constant than the first snap-action disc 30 and the spring disc 28 together.

(40) In this way, the second snap-action disc 44 provides the self-holding function, which keeps the switch 10 open even after the temperature has fallen below the first reset temperature. This self-holding function is only deactivated when the switch 10 also cools down to or below the second reset temperature. Only then does the second snap-action disc 44 switch from its high-temperature configuration back to its low-temperature configuration so that the switch 10 is closed and the first switching position shown in FIG. 1 is obtained.

(41) The second snap-action disc 44 is preferably designed in such a way that its second reset temperature is below room temperature. The switch 10 can therefore only be reset after it has been opened by means of external cold treatment, for example with a cold spray.

(42) The switch 10 as shown in the second example in FIG. 5 is generally based on the same functional principle as the switch 10 according to the first embodiment shown in FIGS. 1-4. In addition to a spring part 28 which is configured as a temperature-independent spring disc, this switch 10 also comprises a first snap-action part 30, which is a temperature-dependent snap-action disc, and a second snap-action part 44, which is also a temperature-dependent snap-action disc. Also in this case, the second snap-action disc 44 causes the self-holding function of the switch 10, which is especially caused by the fact that the (second) reset temperature of the second snap-action disc 44 is lower than the (first) reset temperature of the first snap-action disc 30.

(43) However, the construction of the switching mechanism 14′ according to the second embodiment of the switch 10 shown in FIG. 5 is slightly different from the first embodiment.

(44) The movable contact part 46′ of the movable contact member 40′ has a slightly different shape here. In addition, the movable contact member 40′ comprises a ring 56 which surrounds the contact member 40′. This ring 56 is preferably pressed onto the movable contact part 46′.

(45) The ring 56 comprises a circumferential shoulder 58 on which the first snap-action disc 30 rests with its center 42. In the low-temperature configuration of the first snap-action disc 30 shown in FIG. 5, the edge 36 of the first snap-action disc 30 is according to this embodiment not supported by the housing 12. The edge 36 of the first snap-action disc 30 is freely suspended in the low-temperature configuration. In the closed state of the switch 10 shown in FIG. 5, the first snap-action disc 30 therefore exerts no force on the movable contact member 40′.

(46) In the closed state of the switch 10, the contact pressure between the movable contact part 46′ of the movable contact member 40′ and the first stationary contact 48 is at least partially caused by the spring disc 28. The spring disc 28 is clamped with its center 38 between the ring 56 and the widened upper section of the contact member 40′.

(47) The spring disc 28 rests with its edge 32 on a spacer element 60. This spacer element 60 is preferably configured as a spacer ring which is inserted into the lower part 16 of the housing 12. A circumferential shoulder 62 is provided on this spacer element 60, which circumferential shoulder serves as support for the edge 32 of the spring disc 28.

(48) The spacer element 60 is clamped between two further spacer rings 64, 66. The spacer ring 64 is arranged above the edge 32 of the spring disc 28 and clamped between the spacer ring 60 and the upper part 18 with the insulating foil 22 interposed. The spacer ring 66 is arranged below the spacer ring 60 and clamped between the latter and the lower part 16 of the housing 12.

(49) In the embodiment shown in FIG. 5, the movable contact member 40′ comprises two separate components in addition to the ring 56, a first component 68, which carries or forms the movable contact member 46′, and a second component 70. The second component 70 is arranged on a lower side of the first component 68 facing away from the first stationary contact 48. The two components 68, 70 of the movable contact member 40′ are preferably connected to each other by means of a non-positive, firmly bonded or positive connection. For example, these two components 68, 70 can be welded, soldered or crimped together. In principle, however, it would also be possible to provide the two components 68, 70 of the movable contact member 40′ as one piece or integrally connected to each other.

(50) The second snap-action disc 44 engages the second component 70 of the movable contact member 40′. Its center 54 rests on a circumferential shoulder 72 formed on the second component 70 and is attached or fixed to the movable contact member 40′ at this point.

(51) In the closed position of the switch 10 shown in FIG. 5, in which the second snap-action disc 30 is in its low-temperature configuration, the edge 52 of the second snap-action disc 44 rests on the inner bottom surface 34 of the lower part 16. In the closed position of the switch 10, the second snap-action disc 44 thus provides the contact pressure between the movable contact part 46′ and the first stationary contact 48 in addition to the spring disc 28.

(52) Furthermore, a disc-shaped, plate-shaped or annular support element 74 is arranged in the housing 12, more precisely in the lower part 16. This support element 74 projects laterally from the outside into the interior of the housing 12. At its edge 76 it is clamped between the distance ring 66 and the distance ring 60. In its center the support element 74 comprises a hole 78 through which the movable contact member 40′ projects.

(53) The support element 74 divides the interior of the housing 12 into two areas, an upper area, in which the spring disc 28 and the first snap-action disc 30 are arranged, and a lower area, in which the second snap-action disc 44 is arranged. In other words, the spring disc 28 and the first snap-action disc 30 are arranged between the upper part 18 and the support element 74, whereas the second snap-action disc 44 is arranged between the support element 74 and the lower part 16.

(54) The general function of the second embodiment of the switch 10 shown in FIGS. 5-8 is generally similar to the function of the switch shown in FIGS. 1-4.

(55) The first snap-action disc 30 is substantially used to open the switch 10, i.e. to move it from its first closed position to its second open position. The second snap-action disc 44 substantially provides the self-holding function which keeps the switch 10 open even if the first snap-action disc 30 switches from its high-temperature configuration back to its low-temperature configuration after the switch 10 has been opened. Therefore, it is also provided in this embodiment of the switch 10 that the (second) switching temperature of the second snap-action disc 44 is equal to or higher than the (first) switching temperature of the first snap-action disc 30. It is also provided that the (second) reset temperature of the second snap-action disc 44 is lower than the (first) reset temperature of the first snap-action disc 30.

(56) When the switch 10 and thus the first snap-action disc 30 heats up to a temperature above the first switching temperature, the first snap-action disc 30 switches from its low-temperature configuration shown in FIG. 5 to its high-temperature configuration shown in FIG. 6. The first snap-action disc 30 is thereby supported with its edge 36 by the lower side of the spring disc 28 and thus moves the spring disc 30 from its first geometric configuration shown in FIG. 5 to its second geometric configuration shown in FIG. 6.

(57) In contrast to the first embodiment, the spring disc 28 and the first snap-action disc 30 thereby exert a spring force on the movable contact member 40′, which spring force is greater than the spring force exerted by the second snap-action disc 44 on the movable contact member 40′ and acting in the opposite direction. If the second switching temperature is higher than the first switching temperature and the second switching temperature has not yet been reached, the second snap-action disc remains in its low-temperature configuration as shown in FIG. 6, in which it presses the movable contact member 40′ in the direction of the first stationary contact 48. However, due to the specified force conditions, the movable contact member 46′ is still lifted off the first stationary contact 48 upon reaching the first switching temperature (see FIG. 6).

(58) In this embodiment of the switch 10, the spring disc 28 and the first snap-action disc 30 do not necessarily have to be designed in such a way that their spring force exerted together on the movable contact member 40′ is greater than the spring force exerted by the second snap-action disc 44 on the movable contact member 40′. If this is not the case, however, the (second) switching temperature of the second snap-action disc 44 shall be the same or even lower than the (first) switching temperature of the first snap-action disc 30. In this case, upon reaching the first switching temperature, the switching position of the switch 10 shown in FIG. 6 would not be reached but directly the switching position of the switch 10 shown in FIG. 7, in which both snap-action discs 30, 44 are in their high-temperature configuration.

(59) In the first case described above, in which the first switching temperature is lower than the second switching temperature and the spring disc 28 together with the first snap-action disc 30 generates a greater force than the second snap-action disc 44, the switch 10 would first be moved to the switching position shown in FIG. 6 upon reaching the first switching temperature and would only be moved to the switching position shown in FIG. 7 upon reaching the second switching temperature.

(60) Nevertheless, in both cases, the switch 10 is opened and the electric circuit is disconnected already upon reaching the first switching temperature.

(61) In the switching position of the switch 10 shown in FIG. 7, the second snap-action disc 44 is in its high-temperature configuration. Its edge 52 is supported by the support element 74 and its center 54 pushes the movable contact member 40′ downwards.

(62) If the switch 10 then cools down again in the further course, the first snap-action disc 30 switches from its high-temperature configuration shown in FIG. 7 back to its low-temperature configuration shown in FIG. 8 upon reaching the first reset temperature. However, since the edge 36 of the first snap-action disc 30 in its low-temperature configuration cannot be supported by a part of the switch but is freely suspended in the housing 12, the first snap-action disc 30 does not exert any force on the movable contact member 40′ to move the movable contact member 46′ in the direction of the first stationary contact 48.

(63) Since the second snap-action disc 44, upon reaching the first reset temperature, remains in its high-temperature configuration as shown in FIG. 8, it presses down the movable contact member 40′ together with the spring disc 28, which remains in its second geometric configuration, so that the movable contact member 46′ remains spaced apart from the first stationary contact 48.

(64) FIG. 9 shows a third embodiment of the switch 10 in its closed position (first switching position). Since the interaction of the spring disc 28, the first snap-action disc 30 and the second snap-action disc 44 is based on a substantially identical or at least very similar functional principle as described with respect to the second embodiment shown in FIGS. 5-8, the other switching positions of the switch 10 according to this third embodiment are not shown again here.

(65) The switch 10 according to the third embodiment shown in FIG. 9 differs from the previous embodiments mainly in the construction of the housing 12″. The lower part 16″ is again made of electrically conductive material. The flat upper part 18″ is made of electrically insulating material. It is held on the lower part 16″ by a bent edge 80.

(66) Between the upper part 18″ and the lower part 16″ a spacer ring 64″ is also provided here, which keeps the upper part 18″ spaced apart from the lower part 16″. On its inside, the upper part 18″ has a first stationary contact 48″ and a second stationary contact 50″. The stationary contacts 48″ and 50″ are designed as rivets which extend through the upper part 18″ and end on the outside in the heads 82, 84, which serve for the external connection of the switch 10.

(67) The switching mechanism 14″ is also designed differently than before. The movable contact member 40″ comprises a current transfer member 86, which in the embodiment shown in FIG. 9 is a contact plate whose upper side is coated with an electrically conductive coating so that it provides an electrically conductive connection between the two contacts 48″ and 50″ when the contact is made at the contacts 48″ and 50″ as shown in FIG. 9.

(68) The current transfer member 86 is connected to the spring disc 28 and the first snap-action disc 30 via a rivet 88, which is also to be regarded as part of the contact member 40″. Similarly as before, a second component 70″ is arranged on the lower side of this rivet 88, which second component comprises a circumferential shoulder 72″ on which the second snap-action disc 44 rests with its center 54.

(69) The main advantage of the switch design shown in FIG. 9 is that, in contrast to the first two embodiments of the switch 10 shown in FIGS. 1-8, no current flows through either the spring disc 28 or the two snap-action discs 30, 44 when the switch 10 is closed. This current only flows from the first external terminal 82 via the first stationary contact 48″, the current transfer member 86 and the second stationary contact 50″ to the second external terminal 84.

(70) It goes without saying that the other construction of the switching mechanism 14″, i.e. in particular the arrangement of the spring disc 28 and the two snap-action discs 30, 44, does not necessarily have to correspond to the arrangement shown in FIG. 9. Therefore, the arrangement of the spring disc 28 and the two snap-action discs 30, 44 do not necessarily have to be identical or similar to the arrangement described in the second embodiment shown in FIG. 5-8, but may also correspond to the arrangement described in the first embodiment shown in FIG. 1-4.

(71) 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.

(72) 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.