Temperature-dependent switch

Abstract

In a temperature-dependent switch having a switching mechanism that has a movable contact part which cooperates with a stationary counter contact and is moved by a spring part to which the movable contact part is electrically conductively connected, the switching mechanism produces an electrically conductive connection between the stationary counter contact and a second counter contact in a temperature-dependent manner. The switch is provided with an arc-shielding plate, which has no mechanical function, is arranged on an upper surface of the spring part and covers sections thereof.

Claims

1. A temperature-dependent switch provided with a stationary counter contact, a second counter contact, and a switching mechanism, said switching mechanism comprising a spring part and a movable contact part, said spring part having an upper surface facing said stationary counter contact, wherein said movable contact part is electrically conductively connected to said spring part, cooperates with said stationary counter contact and is moved by said spring part, the switching mechanism producing an electrically conductive connection between the stationary counter contact and said second counter contact in a temperature-dependent manner, the switching mechanism comprising further an arc-shielding plate having no mechanical function and being arranged on said upper surface of said spring part, said arc-shielding plate covering at least one area of said upper surface, wherein the arc-shielding plate comprises a closed annular region, said closed annular region covering said at least one area on said upper surface of said spring part, said at least one area being an annular area extending around the movable contact part, and wherein the arc-shielding plate comprises three strips extending in a star-shaped manner from the annular region.

2. The switch of claim 1, wherein said arc-shielding plate is electrically conductively connected to said movable contact part.

3. The switch of claim 1, wherein said annular region extends beneath the movable contact part.

4. The switch of claim 1, wherein the movable contact part has a diameter and the annular area comprises a width that corresponds to from 10% to 40% of said diameter of said movable contact part.

5. The switch of claim 1, wherein at least one strip extends at least as far as a rim of the spring part.

6. The switch of claim 1, wherein the arc-shielding plate is electrically conductively connected to the second counter contact.

7. The switch of claim 1, wherein the arc-shielding plate is manufactured in one piece from a copper sheet which has a thickness of less than 0.1 mm.

8. The switch of claim 1, wherein the arc-shielding plate is manufactured in one piece from a copper sheet.

9. The switch of claim 7, wherein the copper sheet is silver-coated.

10. The switch of claim 1, wherein the spring part is disc-shaped and is electrically conductively connected via its rim to said second counter contact, at least when said switch is closed.

11. The switch of claim 1, wherein the spring part is a spring disc which presses the movable contact part towards the stationary counter contact, the switching mechanism further comprising a temperature-dependent snap disc which, in one geometric temperature position, lifts the movable contact part from the stationary counter contact.

12. The switch of claim 11, wherein the movable contact part is arranged centrally on the spring disc.

13. The switch according of claim 1, further comprising a housing on which the stationary counter contact and the second counter contact) are provided, the switching mechanism being arranged within said housing.

14. The switch of claim 13, wherein the spring disc has a rim, the spring disc being fixed via its rim to the housing.

15. The switch according to claim 13, wherein the housing comprises a lower part and an upper part having an inner surface and closing said lower part, the stationary counter contact being arranged on said inner surface of the upper part.

16. The switch of claim 1, wherein the arc-shielding plate covers up to a maximum of 50% of said upper surface of said spring part.

17. The switch of claim 1, wherein the spring part is a temperature-dependent bi-stable snap disc having a first geometric temperature position, in which it lifts the movable contact part from the stationary counter contact, and a second geometric temperature position, in which it presses the movable contact part against the stationary counter contact.

18. The switch of claim 17, wherein the movable contact part is arranged centrally on the snap disc.

19. The switch of claim 17, wherein the bi-stable snap disc is a bimetal or a trimetal snap disc.

20. A temperature-dependent switch provided with a stationary counter contact, a second counter contact, and a switching mechanism, said switching mechanism comprising a spring part and a movable contact part, said spring part having an upper surface facing said stationary counter contact, wherein said movable contact part is electrically conductively connected to said spring part, cooperates with said stationary counter contact and is moved by said spring part, the switching mechanism producing an electrically conductive connection between the stationary counter contact and said second counter contact in a temperature-dependent manner, the switching mechanism comprising further an arc-shielding plate that does not contribute to any mechanical switching function of said switch, said arc-shielding plate being arranged on said upper surface of said spring part and covering at least one area of said upper surface, wherein the spring part is a spring disc which presses the movable contact part towards the stationary counter contact, the switching mechanism further comprising a temperature-dependent snap disc which, in one geometric temperature position, lifts the movable contact part from the stationary counter contact and wherein the arc-shielding plate is permanently electrically conductively connected to the second counter contact.

21. The switch of claim 20, wherein the movable contact part is arranged centrally on the spring disc.

22. The switch of claim 20, wherein the arc-shielding plate comprises a closed annular region, said closed annular region covering said at least one area on said upper surface of said spring part, said at least one area being an annular area extending around the movable contact part.

23. The switch of claim 22, wherein the arc-shielding plate comprises at least one strip extending radially from said annular region.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Embodiments of the invention are illustrated in the accompanying drawing and will be explained in greater detail in the following description. In the drawings:

(2) FIG. 1 shows a schematic side view of a temperature-dependent switch with arc-shielding plate, in the closed state;

(3) FIG. 2 shows the switch from FIG. 1 in the open state;

(4) FIG. 3 shows a plan view of the switching mechanism from the switch from FIG. 1;

(5) FIG. 4 in an illustration similar to FIG. 3 shows a switching mechanism with a further embodiment for an arc-shielding plate;

(6) FIG. 5 shows an illustration, enlarged in portions, of a temperature-dependent switch in which the arc-shielding plate is connected to the lower part of the housing; and

(7) FIG. 6 shows a plan view of the switching mechanism from the switch from FIG. 5.

DESCRIPTION OF PREFERRED EMBODIMENTS

(8) FIG. 1 shows a schematic side view of a temperature-dependent switch 10, which is circular in plan view and has a temperature-dependent switching mechanism 11 which is arranged in a housing 12.

(9) The housing 12 comprises a cup-like lower part 14, which is closed by an upper part 15. In the lower part 14, a peripheral shoulder 16 is provided, on which a spacer ring 17 is arranged, on which the upper part 15 rests with intermediate positioning of an insulating film 18.

(10) The lower part 14 holds the upper part 15 on the peripheral rim 16 by means of its inwardly bent upwardly protruding edge 19.

(11) The lower part 14 and upper part 15 are manufactured in the shown embodiment from electrically conductive material, which is why the insulating film 18 is provided and electrically insulates the lower part 14 and the upper part 15 with respect to one another.

(12) A further insulating covering 22 is provided on an outer surface 21 of the upper part 15, whereas a stationary counter contact 24 is arranged on an inner surface 23 of the upper part 15.

(13) A movable contact part 25 carried by the switching mechanism 11 cooperates with this stationary counter contact 24.

(14) The switching mechanism 11 comprises a snap-action spring disc 26, which is fixed via its rim 27 between the ring 16 and the lower part 14, such that it produces an electrically conductive connection there.

(15) A bimetallic snap-action disc 28 is provided beneath the snap-action spring disc 26 and has two geometric temperature positionsthe low-temperature position shown in FIG. 1 and the high-temperature position shown in FIG. 2.

(16) The bimetallic snap-action disc 28 lies with its rim 29 freely above a wedge-shaped peripheral shoulder 31, which is formed on an inner base 32 of the lower part 14.

(17) The lower part 14 also has an outer base 33, which together with the outer surface 21 of the upper part 15 serves as the external connection of the switch 10 from FIG. 1.

(18) The bimetallic snap-action disc 28 is supported by its center 35 on a peripheral shoulder 34 of the contact part 25.

(19) In the closed switch position of the switch 10 shown in FIG. 1, the movable contact part 25 is pressed against the stationary counter contact 24 by the snap-action spring disc 26. Because the electrically conductive snap-action spring disc 26 is connected via its rim 27 to the lower part 16, which serves here as a second counter contact of the switching mechanism 11, an electrically conductive connection is thus produced between the two external connections 21, 33.

(20) If the temperature in the interior of the switch 10 now rises beyond the response temperature of the bimetallic snap-action disc 28, this thus turns from the convex configuration shown in FIG. 1 into a concave configuration, in which its rim 29 in FIG. 1 moves upwardly, such that it contacts the rim 27 of the snap-action spring disc 26 from below.

(21) Here, the bimetallic snap-action disc 28 presses via its center 35 against the shoulder 34 and thus lifts the movable contact part 25 from the stationary counter contact 24, as is shown in FIG. 2.

(22) The snap-action spring disc 26 may be a bi-stable spring disc, which is also geometrically stable in the position in FIG. 2, such that the movable contact part 25 then also does not contact the stationary counter contact 24 again if the rim 29 of the bimetallic snap-action disc 28 no longer presses against the rim 27 of the snap-action spring disc 26.

(23) If the temperature in the interior of the switch 10 now drops again, the rim 29 of the bimetallic snap-action disc 28 in FIG. 2 thus moves downwardly and contacts the wedge-shaped shoulder 31. The bimetallic snap-action disc 28 then presses via its center 35 against the snap-action spring disc 26 from below and presses this back into its other geometrically stable position, in which it presses the movable contact part 25 against the stationary counter contact 24 in accordance with FIG. 1.

(24) When passing from the closed switch position according to FIG. 1 into the open switch position according to FIG. 2, an arc is produced between the stationary counter contact 24 and the movable contact part 25 and leads to contact erosion and, after repeated switching cycles and consequent damage to the surfaces of the contact part 25 and counter contact 24, migrates to the spring part carrying the movable contact part 25. This spring part is the snap-action spring disc 26 in the present embodiment, wherein, instead of the snap-action spring disc 26, merely the bimetallic snap-action disc 28 may also be provided, which then for example would be fixed by its rim 29 beneath the peripheral ring 16, although this is not necessary.

(25) In order to now avoid or at least considerably reduce the damage caused by the arcs produced, an arc-shielding plate 38 is arranged on the snap-action spring disc 26, more specifically on its upper surface 37 facing the stationary counter contact 24, and is electrically conductively connected to the movable contact part 25, but mechanically is devoid of function.

(26) The arc-shielding plate 38 is a part stamped from a copper sheet having a thickness of 0.05 mm, such that it performs no spring function at all and does not mechanically load or impair the switching movement of the switching mechanism 11.

(27) This arc-shielding plate 38 nevertheless causes both the switched current intensity and the life period of the switch 10 to be considerably increased compared to a switch of identical design, but without an arc-shielding plate 38.

(28) As can be seen in FIG. 1, the movable contact part 25 has a pin 39, onto which a ring 40 is pressed, such that both the snap-action spring disc 26 and the arc-shielding plate 38 are fixed between the ring 40 and the contact part 25. The shoulder 34 on which the center 35 of the bimetallic snap-action disc 28 rests is formed on the ring 40.

(29) FIG. 3 shows a plan view of the temperature-dependent switching mechanism 11 from the switch 10 according to FIGS. 1 and 2.

(30) It can be seen in FIG. 3 that the arc-shielding plate 38 covers an annular area 41 on the upper surface 37 around the movable contact part 25, said annular area having a width 42 that is approximately 30% of the diameter 43 of the movable contact part 25.

(31) The closed annular area 41 bears directly against the movable contact part 25 because the arc-shielding plate 38 has an annular region 44 which is illustrated in a dotted manner in FIG. 3 and extends beneath the movable contact part 25, where it has a through-opening 45, of which the diameter 46 corresponds to the diameter of the pin 39 of the movable contact part 25.

(32) The dotted annular region 44 has a width indicated at 47 that is smaller than the diameter 43 of the contact part 25.

(33) A strip 49 of the arc-shielding plate 38 extends from the annular region 44 to a rim 48 in the direction of the edge 27 of the snap-action spring disc 26.

(34) The arrangement is selected such that the rim 48 is set back so far from the rim 27 that the arc-shielding plate does not reach as far as the spacer ring 17, as can be seen in FIG. 1.

(35) Already this shielding plate 38, which covers approximately 30% of the upper surface 37, leads to the effect described in detail in the introduction, in accordance with which the life period and the breaking capacity of the switch are considerably increased.

(36) FIG. 4, in an illustration similar to FIG. 3, shows the switching mechanism 11 with a further embodiment for the arc-shielding plate 38. The annular region 44 can again be seen around the movable contact part 25, a first strip 49 now extending to the right from said annular region to the rim 38 and a second strip 51 now extending to the left from said annular region to a rim 52 which, similarly to the rim 48, does not reach as far as the rim 27 of the snap-action spring disc 26.

(37) The covered area of the upper surface 37 is enlarged by the arc-shielding plate 38 to approximately 40% compared with the embodiment according to FIG. 3, which leads to better protection still.

(38) Whereas, in accordance with the embodiments in FIGS. 1 to 4, the arc-shielding plate 38, 38 is indeed electrically connected to the movable contact part 25, but does not reach beyond the snap-action spring disc 26, an embodiment is shown in FIG. 5 in which the arc-shielding plate 38 is also electrically conductively connected to the second counter contact, that is to say the lower part 14.

(39) The right lower region of a temperature-dependent switch 10 is shown in part in FIG. 5 and for the rest is constructed similarly to the switch 10 from FIGS. 1 and 2. The differences will be explained below.

(40) A recess 54 is provided in the spacer ring 17 and is designed such that an end 55 of the arc-shielding plate 38 protrudes there, such that it is fixed between the spacer ring 17 and lower part 14.

(41) The snap-action spring disc 26 now rests via its center 56 on a shoulder 57 of the ring 40, that is to say is no longer securely fixed between the movable contact part 25 and the ring 40.

(42) By contrast, the arc-shielding plate 38 is fixed via its center 58 between the movable contact part 25 and the ring 40.

(43) The arc-shielding plate 38 is thus electrically connected both to the movable contact part 25 and to the lower part 14, that is to say the second counter contact of the switch 10.

(44) A plan view of the switching mechanism 11 from the switch 10 according to FIG. 5 is shown in FIG. 6.

(45) The arc-shielding plate 38 again comprises the annular region 44, which extends beneath the movable contact part 25. Three strips 61, 62, 63 proceed in a star-shaped manner from this annular region 44, the rims 64, 65, 66 of said strips protruding beyond the rim 27 of the snap-action spring disc 26, such that they reach into the recess 54 in the spacer ring 17.

(46) It can be seen from FIG. 6 that, even with the arc-shielding plate 38, more than 50% of the upper surface 37 of the snap-action spring disc 26 remains uncovered by the arc-shielding plate 38.