Temperature-dependent switch
11749479 · 2023-09-05
Inventors
Cpc classification
H01H2037/549
ELECTRICITY
H01H2037/705
ELECTRICITY
International classification
Abstract
A temperature-dependent switch comprising first and second stationary contacts and a temperature-dependent switching mechanism having a movable contact member. The switching mechanism, in its first switching position, presses the contact member against the first contact and thereby produces an electrically conductive connection and, in its second switching position, keeps the contact member spaced apart from the first contact and thereby disconnects the electrically conductive connection. The switch further comprises a closing lock that, once activated, prevents the switch once having opened from closing again by keeping the switching mechanism in its second switching position. The closing lock comprises a locking element having a shape-memory alloy and is configured to change its shape upon exceeding a locking element switching temperature from a first shape, in which the locking element does not activate the closing lock, into a second shape, in which the locking element activates the closing lock.
Claims
1. A temperature-dependent switch, comprising: a first stationary contact, a second stationary contact, and a temperature-dependent switching mechanism having a movable contact member, wherein in a first switching position, the switching mechanism presses the movable contact member against the first stationary contact, thereby producing 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, the switching mechanism keeps the movable contact member spaced at a distance from the first stationary contact, thereby disconnecting the electrically conductive connection, wherein the temperature-dependent switching mechanism comprises a temperature-dependent snap-action part, which is configured to switch from a geometric low-temperature configuration to a geometric high-temperature configuration upon reaching a switching temperature, and which is configured to switch back from the geometric high-temperature configuration to the geometric low-temperature configuration upon subsequently reaching a reset temperature that is lower than the switching temperature, wherein a switching of the temperature-dependent snap-action part from the geometric low-temperature configuration to the geometric high-temperature configuration moves the switching mechanism from the first switching position to the second switching position, thereby opening the switch, wherein a closing lock is provided that, as long as it is activated, prevents the switch once having opened from closing again by keeping the switching mechanism in its second switching position, wherein the closing lock comprises a locking element which comprises a shape-memory alloy and an opening through which the movable contact member protrudes, wherein the shape-memory alloy is configured to change a shape of the locking element upon reaching a locking element switching temperature from a first shape, in which the locking element does not activate the closing lock, to a second shape, in which the locking element activates the closing lock by exerting a force on a part of the switching mechanism, which force holds the switching mechanism in its second switching position, wherein the shape-memory alloy is a shape-memory alloy with two-way memory effect, and wherein the locking element is configured to change its shape from the second shape to the first shape when falling below a locking element reset temperature that is lower than the locking element switching temperature, wherein the locking element switching temperature is equal to or higher than the switching temperature of the temperature-dependent snap-action part, and wherein the locking element reset temperature is lower than the reset temperature of the temperature-dependent snap-action part.
2. The switch according to claim 1, wherein the locking element is plate-shaped or disc-shaped.
3. The switch according to claim 1, wherein the opening comprises a through hole.
4. The switch according to claim 1, wherein the opening is arranged centrally in the locking element.
5. The switch according to claim 1, wherein the locking element comprises at least one slit that adjoins the opening.
6. The switch according to claim 5, wherein the at least one slit is rectilinear and extends radially outward from the opening.
7. The switch according to claim 1, wherein the locking element comprises at least three slits, each of which adjoins the opening, is rectilinear and extends radially outward from the opening.
8. The switch according to claim 1, wherein the housing comprises a lower part and an upper part that is attached to the lower part, wherein the locking element rests on a circumferential shoulder that is arranged in the lower part, and wherein the locking element is clamped between the lower part and the upper part.
9. The switch according to claim 1, wherein the locking element is arranged on a first side of the temperature-dependent snap-action part facing the first contact and is configured to exert in its second shape the force directly or indirectly on the temperature-dependent snap-action part.
10. The switch according to claim 1, wherein the locking element is arranged on a second side of the temperature-dependent snap-action part facing away from the first contact and is configured to exert in its second shape the force directly or indirectly on the contact member.
11. The switch according to claim 1, wherein the switching mechanism comprises a temperature-independent spring part which is connected to the movable contact member, wherein the temperature-dependent snap-action part acts on the spring part upon reaching the switching temperature and thereby lifts off the movable contact member from the first contact.
12. The switch according to claim 1, wherein the temperature-dependent snap-action part is a bimetal or trimetal snap-action disc.
13. The switch according to claim 11, wherein the movable contact member comprises a movable contact part that is configured to interact with the first contact, and wherein the spring part is configured to interact with the second contact.
14. The switch according to claim 1, wherein the movable contact member comprises a current transfer member that is configured to interact with first stationary contact and the second stationary contact.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1)
(2)
(3)
(4)
(5)
(6)
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(8)
DESCRIPTION OF PREFERRED EMBODIMENTS
(9)
(10) The switch 10 comprises a housing 12 in which a temperature-dependent switching mechanism 14 is arranged. The housing 12 comprises a pot-shaped lower part 16 and an upper part 18, which is held to the lower part 16 by a bent or flanged upper edge 20.
(11) In the embodiment shown in
(12) The insulating foil 24 provides electrical insulation of the upper part 18 against the lower part 16. The insulating foil 24 also provides a mechanical seal that prevents liquids or impurities from entering the interior of the housing from outside.
(13) 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.
(14) Another insulating foil 26 can be applied to the outside of the upper part 18, as shown in
(15) The switching mechanism 14 comprises a temperature-independent spring part 28 and a temperature-dependent snap-action part 30. The spring part 28 is preferably designed as a bistable spring disc. Accordingly, it has two temperature-independent stable geometric configurations. The first configuration is shown in
(16) The temperature-independent spring disc 28 rests with its edge 32 on a further circumferential shoulder 34 formed in the lower part 16. In its low-temperature configuration, the temperature-dependent bimetal snap-action disc 30 can be freely suspended in the housing 12 in such a way that its edge 36 does not contact the housing 12. Among other things, this has the advantage that the closing pressure in the closed state of the switch 10 is generated by the spring disc 28 alone. Also, when the switch 10 is closed, the current then flows only through the spring disc 28, but not through the bimetal snap-action disc 30.
(17) The edge 36 of the bimetal snap-action disc 30 in its low-temperature configuration can alternatively rest on the inner bottom surface 38 of the lower part 16. For this purpose, the inner bottom surface 38 may be laterally raised, as indicated by the dotted line 39 in
(18) The temperature-independent spring disc 28 is with its center 40 fixed to a movable contact member 42 of the switching mechanism 14. The temperature-dependent bimetal snap-action disc 30 is with its center 44 also fixed to this movable contact member 42.
(19) The movable contact member 42 comprises a contact part 46 and a ring 45 which is pressed onto the contact part 46. The ring 45 comprises a circumferential shoulder 47 on which the bimetal snap-action disc 30 rests with its center 44. The spring disc 28 is clamped between the ring 45 and the upper, widened section of the contact part 46. In this way, the temperature-dependent switching mechanism 14 is a captive unit consisting of contact member 42, spring disc 28 and bimetal 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.
(20) The contact part 46 of the movable contact member 42 interacts with a fixed counter contact 48, which is arranged inside 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 serves as the second stationary contact 50.
(21) In the position shown in
(22) In the closed low-temperature position of the switch 10 as shown in
(23) If the temperature of the device to be protected, and thus the temperature of the switch 10 and the temperature-dependent bimetal snap-action disc 30 arranged therein now increases, the snap-action disc will switch from the low-temperature configuration shown in
(24) If the device to be protected and thus the switch 10 together with the temperature-dependent bimetal snap-action disc 30 then cool down again, the bimetal snap-action disc 30, upon reaching its reset temperature, would actually snap back to its low-temperature configuration as shown in
(25) The closing lock 52 comprises a locking element 54, which is substantially plate-shaped or disc-shaped. In the first embodiment shown in
(26) An embodiment of the locking element 54 is shown in
(27) In its first shape, the locking element 54 has substantially the shape of a circular disc. It comprises an opening 56, which in the embodiment shown here is designed as a centrally arranged hole. The movable contact member 42 of the switching mechanism 14 protrudes through the opening 56 (see
(28) The edge 58 of the locking element 54, with which it is attached to the housing 12, is preferably made of an electrically insulating material or coated with an electrically insulating material. This additionally improves the electrical insulation between the lower part 16 and the upper part 18. In addition, the stability of the clamping of the locking element 54 in the housing 12 can be increased.
(29) For example, the base body of the locking element 54 can be made entirely of the shape-memory alloy, which is provided with an adhesive foil or plastic coating 60 at the edge 58. This adhesive foil or plastic coating 60 is preferably applied to both sides of the shape-memory alloy base body.
(30) The locking element 54 shown in
(31) The slits 62 allow a kind of unfolding of the locking element 54 when the shape-memory alloy brings the locking element 54 into its second shape upon reaching the locking element switching temperature. The four sectors of the locking element 54 that are separated by the slits 62 then fold down as shown in
(32) In
(33) In principle, such a temperature-related change in shape can also be achieved with a shape-memory alloy locking element without slits 62 or with fewer slits 62. Slit 62, however, helps to reduce internal stresses caused by the deformation of the locking element 54. In addition, the shape change of the locking element 54 can be increased.
(34) In the first embodiment shown in
(35) If the temperature of the switch 10 and thus also the temperature of the locking element 54 now increases further, the shape-memory alloy causes the already mentioned shape change of the locking element 54 when the locking element switching temperature is reached, so that it assumes its second shape as shown in
(36) Even if the switch 10 now cools down again starting from the situation shown in
(37) Even if the inner bottom surface 38 is laterally raised, as indicated in
(38) In order to be able to effectively prevent an inadvertent closing of the switch 10 with the closing lock 52 activated, even if the bimetal snap-action disc 30 in its low-temperature configuration can rest on the housing 12, the spring constant of the locking element 54 is in such case preferably higher than the spring constant of the bimetal snap-action disc 30.
(39) Depending on the design of the locking element 54, deactivation of the closing lock 52 is either not possible at all or is possible by a cold treatment.
(40) In the first case of an irreversible closing lock 52, the switch 10 is a one-time switch. For this purpose, a shape-memory alloy with a one-way memory effect is selected for the locking element 54.
(41) By using a shape-memory alloy with a two-way memory effect, the closing lock 52 can alternatively be configured to be reversible. In this case, the shape-memory alloy of the locking element 54 is configured to return the shape of the locking element 54 from the second shape shown in
(42) The shape-memory alloy of the locking element 54 is preferably configured such that the locking element reset temperature is lower than the reset temperature of the bimetal snap-action disc 30. For example, the shape-memory alloy of the locking element 54 can be configured such that the locking element reset temperature is lower than room temperature and, for example, set to be in a temperature range of 0-15° C. By means of a cold treatment, the closing lock 52 can thus be released again so that the switch 10 would return from the switching position shown schematically in
(43)
(44)
(45) The switching function as well as the interaction between the switching mechanism 14 and the closing lock 52 in the second embodiment shown in
(46) In contrast to the first embodiment, the locking element 54 of the closing lock 52 in the second embodiment shown in
(47) The locking element 54 is clamped between two spacer rings 64, 66. The first spacer ring 64 is arranged on the inner bottom surface 38 of the lower part 16. The locking element 54 rests on this first spacer ring 64. The second spacer ring 66 is arranged on the locking element 54. The bimetal snap-action disc 30 rests with its edge 36 on the upper side of the second spacer ring 66.
(48) A further spacer ring 68 is arranged at the position where the locking element 54 was arranged between the lower part 16 and the upper part 18 according to the first embodiment. This spacer ring 68 serves as a spacer between the lower part 16 and the upper part 18. Furthermore, the spring disc 28 can be supported from below by this spacer ring 68 when the switching mechanism 14 is in its second switching position (see
(49) In the second embodiment of the switch 10 shown in
(50) The locking element 54 is designed in the same way as mentioned above with regard to the first embodiment shown in
(51) Also in this embodiment, the closing lock 52 can be designed reversibly or irreversibly, depending on whether a shape-memory alloy with a one-way memory effect or a shape-memory alloy with a two-way memory effect is used for the shape-memory alloy of the locking element 54.
(52)
(53) Since the interaction between the switching mechanism 14′ and the closing lock 52 is realized in the same way as mentioned before with the switch 10′ shown in
(54) The design of the switch 10′ shown in
(55) 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 to the lower part 16′ by the bent edge 20′.
(56) A spacer ring 68′ is provided between the upper part 18′ and the lower part 16′ to keep the upper part 18′ at a distance from the lower part 16′. On its inside, the upper part 18′ comprises a first stationary contact 48′ and a second stationary contact 50′. The contacts 48′ and 50′ are designed as rivets which extend through the upper part 18′ and end outside in the heads 72, 74 which serve for the external connection of the switch 10′.
(57) The movable contact member 42′ here comprises a current transfer member which is designed as a contact plate, the upper side of which is coated with an electrically conductive coating so that the current transfer member 76, in the closed position of the switch 10 shown in
(58) A difference of the switch design shown in
(59) The locking element 54 of the closing lock 52 engages the rivet 78 as soon as the closing lock 52 is activated, i.e. as soon as the temperature of the switch 10′ and thus the temperature of the locking element 54 exceeds the locking element switching temperature. Similar to the second embodiment shown in
(60) In principle, the closing lock 52 can also be designed for the switch 10′, as shown schematically in
(61) A reversible design of the closing lock 52 is also possible with the third embodiment of the switch 10′ shown in
(62) 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.
(63) 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.