Temperature-dependent switch

Abstract

A temperature-dependent switch comprising a housing, which comprises a cover part and a lower part, wherein an insulating foil is arranged between the cover part and the lower part. The temperature-dependent switch further comprises a first external contact surface provided externally on the housing, a second external contact surface provided externally on the housing, and a temperature-dependent switching mechanism arranged in the housing. The temperature-dependent switching mechanism, depending on its temperature, establishes or opens an electrically conductive connection between the first and the second external contact surfaces. The insulating foil is at least partially coated or printed with a sealing agent which, for sealing the housing, contacts the cover part and/or the lower part in a sealing area.

Claims

1. A temperature-dependent switch, comprising: a housing having a cover part and a lower part; an insulating foil arranged between the cover part and the lower part, having a circumferential inner edge arranged inside the housing and a circumferential outer edge arranged outside the housing; a first external contact surface provided externally on the housing; a second external contact surface provided externally on the housing; and a temperature-dependent switching mechanism that is arranged in the housing, and that, depending on its temperature, establishes or opens an electrically conductive connection between the first external contact surface and the second external contact surface; wherein, on at least one of a lower side of the insulating foil facing the lower part of the housing or an upper side of the insulating foil facing the cover part of the housing, the insulating foil is only partially coated or printed with a sealing agent in a sealing area where the insulating foil is clamped between the lower part of the housing and the cover part of the housing, the sealing agent forms a closed contour on the insulating foil and is spaced from the circumferential inner edge as well as from the circumferential outer edge.

2. The temperature-dependent switch according to claim 1, wherein the sealing agent comprises a plastic or wax.

3. The temperature-dependent switch according to claim 1, wherein the sealing agent comprises a thermoplastic, a thermoset or an elastomer.

4. The temperature-dependent switch according to claim 1, wherein the sealing agent is configured to be retroactively activated by heating after having been installed in the housing.

5. The temperature-dependent switch according to claim 1, wherein the insulating foil comprises a polyimide or an aromatic polyamide.

6. The temperature-dependent switch according to claim 1, wherein the insulating foil comprises a central hole that is surrounded by the sealing agent.

7. The temperature-dependent switch according to claim 1, wherein the insulating foil is coated or printed with the sealing agent on the upper side of the insulating foil facing the cover part of the housing, and wherein a cutting burr is provided on the lower part of the housing, wherein the cutting burr penetrates into the lower side of the insulating foil.

8. The temperature-dependent switch according to claim 1, wherein the insulating foil is coated or printed with the sealing agent both on the upper side of the insulating foil and on the lower side of the insulating foil.

9. The temperature-dependent switch according to claim 1, wherein, in the sealing area, an edge of the cover part of the housing presses or is pressed onto the insulating foil.

10. The temperature-dependent switch according to claim 1, wherein an upper section of the lower part overlaps the cover part, wherein a circumferential shoulder is provided in the lower part, on which the cover part rests with the insulating foil interposed between the circumferential shoulder and the cover part, wherein the upper section of the lower part presses the cover part onto the circumferential shoulder, and wherein the sealing area is arranged on the circumferential shoulder or on a lower edge of the cover part facing the circumferential shoulder.

11. The temperature-dependent switch according to claim 1, wherein the temperature-dependent switching mechanism carries a movable contact part that interacts with a stationary counter contact that is arranged on a lower side of the cover part facing the lower part and interacts with the first external contact surface.

12. The temperature-dependent switch according to claim 1, wherein the temperature-dependent switching mechanism comprises a bimetal part.

13. The temperature-dependent switch according to claim 1, wherein the temperature-dependent switching mechanism comprises a snap-action spring disc.

14. The temperature-dependent switch according to claim 1, wherein the sealing agent has an annular shape on the insulating foil.

15. A temperature-dependent switch, comprising: a housing having a cover part and a lower part; an insulating foil arranged between the cover part and the lower part; a first external contact surface provided externally on the housing; a second external contact surface provided externally on the housing; and a temperature-dependent switching mechanism that is arranged in the housing, and that, depending on its temperature, establishes or opens an electrically conductive connection between the first external contact surface and the second external contact surface; wherein, on a lower side of the insulating foil facing the lower part of the housing, the insulating foil is only partially coated or printed with a sealing agent in a sealing area where the insulating foil is clamped between the lower part of the housing and the cover part of the housing, the sealing agent forms a closed contour on the insulating foil, and wherein a cutting burr is provided on the cover part of the housing, wherein the cutting burr penetrates into the upper side of the insulating foil.

16. A method of manufacturing a temperature-dependent switch, comprising the steps of: providing a housing having a lower part and a cover part; providing a temperature-dependent switching mechanism which, as a function of its temperature, establishes or opens an electrically conductive connection between a first external contact surface provided externally on the housing and a second contact surface provided externally on the housing; providing an insulating foil having a circumferential inner edge and a circumferential outer edge; before mounting the cover part on the lower part, on at least one of a lower side of the insulating foil or an upper side of the insulating foil, only partially coating or printing the insulating foil with a sealing agent that forms a closed contour on the insulating foil and is spaced from the circumferential inner edge as well as from the circumferential outer edge; and mounting the housing, wherein the temperature-dependent switching mechanism is arranged in the housing and the cover part is mounted on the lower part with the insulating foil interposed between the cover part and the lower part in such a way that the sealing agent for sealing the housing contacts the cover part and/or the lower part in a sealing area where the insulating foil is clamped between the lower part of the housing and the cover part of the housing and in such a way that the circumferential inner edge is arranged inside the housing and the circumferential outer edge is arranged outside the housing.

17. The method according to claim 16, wherein the temperature-dependent switch is heated to activate the sealing agent after mounting the housing.

18. The method according to claim 16, wherein the sealing agent has an annular shape on the insulating foil.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

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

(2) FIG. 2 a schematic sectional view of the first embodiment of the switch shown in FIG. 1, in a second switching position;

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

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

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

(6) FIG. 6 a schematic sectional view of a fifth embodiment of the switch in the first switching position; and

(7) FIG. 7 a schematic top view of an insulating foil that can be used in the switch.

DESCRIPTION OF PREFERRED EMBODIMENTS

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

(9) The switch 10 comprises a housing 12, in which a temperature-dependent switching mechanism 14 is arranged. The housing 12 comprises a pot-like lower part 16 and a cover part 18, which is held on the lower part 16 by a bent or flanged rim 20.

(10) Both the lower part 16 and the cover part 18 are made of an electrically conductive material, preferably metal. The cover part 18 rests on a shoulder 24 inside the lower part 16, with an insulating foil 22 interposed there between. The upper edge 20 of the lower part 16 is bent radially inwards in such a way that it presses the cover part 18 onto the circumferential shoulder 24 with the insulating foil 22 interposed there between.

(11) The insulating foil 22 provides an electrical insulation of the cover part 18 against the lower part 16 and includes a circumferential inner edge 37 arranged inside the housing and a circumferential outer edge 39 arranged outside the housing. In addition, the insulating foil 22 also provides a mechanical seal that prevents liquids or impurities from entering the inside of the housing from the outside.

(12) The insulating foil 22 runs inside the housing 12 parallel to the cover part 18 along the lower side 25 of the cover part, from where it is led laterally between the cover part 18 and the circumferential shoulder 24 up to the upper side 23 of the cover part 18 and out of the housing 12. The bent or flanged upper edge 20 of the lower part 16 lies flat on the upper edge section of the insulating foil 22 and presses it towards the upper side 23 of the cover part 18.

(13) The insulating foil 22 is coated with a sealing agent 26. The sealing agent 26 is preferably a plastic (thermoplastic, thermoset or elastomer) or a wax.

(14) In the first embodiment of the switch 10 shown in FIG. 1, the sealing agent 26 is applied to an upper side 27 of the insulating foil 22 facing the cover part 18. In the mounted state of the switch 10, the sealing agent 26 contacts the cover part 18 in a sealing area 29. This sealing area 29 is highlighted in FIG. 1 by a circle.

(15) In this embodiment, the sealing area 29 extends circumferentially along the outer, lower edge of the cover part 18 and, from there, a bit vertically upwards along the outer circumference of the cover part 18 and radially inwards along a radially outer part of the lower side 25 of the cover part 18. Seen in the cross-section, the sealing agent 26 is thus essentially L-shaped.

(16) FIG. 7 shows a schematic top view of the insulating foil 22 from above, which includes a circumferential inner edge 37 and a circumferential outer edge 39. As can be seen, the sealing agent 26 is applied to the insulating foil 22 in an annular area 31. Sealing agent 26 preferably forms a closed contour. This ensures a seal along the entire circumference between the cover part 18 and the lower part 16. It goes without saying that, depending on the shape of the insulating foil 22, the area 31 does not necessarily have to be circular, but can also be oval or elliptical, for example.

(17) The area 31 where the sealing agent 26 is applied to the insulating foil 22 is positioned in such a way that the sealing agent 26 is automatically arranged in the desired sealing area 29 when the insulating foil 22 is mounted in the housing 12. The area 31 is preferably located at a radial distance from a hole 33 that is arranged centrally in the insulating foil 22. This hole 33 allows a part of the temperature-dependent switching mechanism of the switch 10 to move through the insulating foil 22, as explained in more detail below.

(18) The sealing agent 26 is preferably a sealing agent that is retroactively activated by heating and is only activated after it has been installed in housing 12. This means that the switch 10 is preferably slightly heated in an oven after installation of the insulating foil 22, which causes at least part of the sealing agent 26 to melt or at least partially liquefy in order to adapt even better to the shape of the insulating foil 22 and the shape of the cover part 18 in the sealing area 29. Subsequent cooling causes the sealing agent 26 to solidify again. This considerably improves the sealing effect of the sealing agent 26. The sealing agent 26 ensures a thorough seal in the sealing area 29.

(19) On the upper side 23 of the cover part 18, the switch 10 shown in FIG. 1 is further provided with a further insulating cover 34, which extends radially outwards from a central area to the insulating foil 22.

(20) The switching mechanism 14 comprises a temperature-independent spring part 28, which is designed as a snap-action spring disc, and a temperature-dependent bimetal part 30, which is designed as a bimetal snap-action disc. The spring part 28 is preferably designed as a bistable spring disc. Accordingly, the spring disc 28 has two temperature-independent stable geometric configurations. The first geometric configuration is shown in FIG. 1.

(21) The temperature-dependent bimetal disc 30 is preferably designed as a bistable snap-action disc. The bimetal 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 bimetal disc 30 is in its low-temperature configuration.

(22) The snap-action spring disc 28 rests with its edge 32 on an inner bottom surface 35 of the lower part 16. The inner bottom surface 35 is substantially concave in shape and is slightly raised at the point where the edge 32 of the snap-action spring disc 28 rests in the first switching position shown in FIG. 1, compared to the central area of the inner bottom surface 35. The bimetal disc 30 rests with its edge 36 on the snap-action spring disc 28 in the low-temperature configuration shown in FIG. 1.

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

(24) On its upper side, the movable contact member 40 comprises a movable contact part 44. The movable contact part 44 interacts with a stationary counter-contact 46, which is arranged at the lower side 25 of the cover part 18. In this embodiment, the upper side 23 of the cover part 18, which is connected to the stationary counter-contact 46 in an electrically conductive manner, serves as first external contact surface 48. The outer side of the lower part 16 serves as second external contact surface 50. For example, the outer bottom surface or the outer side of the bent upper edge 20 of the lower part 16 can serve as second external contact surface 50.

(25) In the closed switching position of the switch 10 shown in FIG. 1, the movable contact part 44 is pressed against the stationary counter contact 46 by the snap-action spring disc 28. Since the electrically conductive snap-action spring disc 28 is, with its edge 32, in contact with the lower part 16, an electrically conductive connection is established between the two external contact surfaces 48, 50.

(26) If the temperature inside the switch 10 now increases above the switching temperature of the bimetal disc 30, the latter snaps from its convex low-temperature configuration shown in FIG. 1 to its concave high-temperature configuration shown in FIG. 2.

(27) In the high-temperature configuration shown in FIG. 2, the bimetal disc 30 is with its edge 36 supported on the lower side 51 of the insulating foil 22 and pushes the movable contact member 40 downwards with its center 42. This lifts the movable contact member 44 off the stationary counter contact 46. The snap-action spring disc 28 thereby snaps from its first geometrically stable configuration shown in FIG. 1 to its second geometrically stable configuration shown in FIG. 2.

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

(29) FIG. 3 shows a second embodiment of the switch 10, which is shown in its first position. In comparison to the first embodiment of the switch 10 shown in FIGS. 1 and 2, the sealing agent 26 is now applied to the lower side 51 of the insulating foil 22 facing the lower part 16 and seals in the sealing area 29, especially between the insulating foil 22 and the lower part 16 of the housing 12.

(30) In the third embodiment of the switch 10 shown in FIG. 4, the insulating foil 22 is coated not only on one side, but on both sides with a sealing agent 26, 26′. Accordingly, the sealing agent 26, 26′ is applied to both the upper side 27 facing the cover part 18 and the lower side 51 of the insulating foil 22 facing the lower part 16. Preferably, the sealing agent 26, 26′ is applied to both sides of the insulating foil 22 in an annular area 31. This further improves the sealing effect, as the sealing agent 26, 26′ in the sealing area 29 seals both the area between the outer lower edge of the cover part and the insulating foil as well as the area between the insulating foil 22 and the circumferential shoulder 24 of the lower part 16.

(31) FIG. 5 shows a further embodiment of the switch 10. Again, the switch 10 is shown here in its first, closed switching position. In the embodiment shown in FIG. 5, the sealing agent 26 is applied again to the upper side 27 of the insulating foil 22, similar to the first embodiment shown in FIGS. 1 and 2. On the lower side 51 of the insulating foil 22, a cutting burr 52 provides an additional seal between the insulating foil 22 and the lower part 16. This cutting burr 52 is configured as a circumferential cutting burr with a closed contour. The cutting burr 52 is preferably configured as a turning groove, which is arranged on the upper side of the shoulder 24. The cutting burr 52 is preferably formed integrally with the lower part 16. On its upper side, the cutting burr has a pointed cutting edge with which the cutting burr 52 penetrates the lower side 51 of the insulating foil 22. The cutting burr 52 thus cuts at least partially into the insulating foil 22 and thus provides a mechanical barrier. In combination with the sealing agent 26 arranged on the upper side 27 of the insulating foil 22, the cutting burr 52 ensures a very good seal on both sides of the insulating foil 22.

(32) The position of the sealing agent 26 and the cutting burr 52 may be reversed in contrast to the embodiment shown in FIG. 5. Such an embodiment is shown in FIG. 6. Here, the cutting burr 52 is arranged at the cover part 18 and the sealing agent 26 is arranged at the lower side 51 of the insulating foil 22. The cutting burr 52 cuts into the upper side 27 of the insulating foil 22 from above and seals the sealing area 29 between the cover part 18 and the insulating foil 22, whereas the sealing agent 26 seals the sealing area 29 between the insulating foil 22 and the lower part 16.

(33) Furthermore, it is also possible to arrange the cutting burr 52 and the sealing agent 26 on the same side of the insulating foil 22. The cutting burr 52 would then cut into a part of the sealing agent 26. This would also result in a very good sealing effect. For example, it would be possible to provide such a cutting burr 52 on both the lower part 16 and the cover part 18 so that one cutting burr 52 would then penetrate into the insulating foil 22 from below and a second cutting burr would penetrate into the insulating foil 22 from above. In this case, the sealing agent 26, 26′ could also be arranged on both sides of the insulating foil 22 as shown in FIG. 4.

(34) 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.

(35) 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.