TEMPERATURE-DEPENDENT SWITCH

Abstract

Temperature-dependent switch, comprising a temperature-dependent switching mechanism having a switching mechanism unit, which comprises a movable contact part coupled to a bimetallic snap-action disc, and having a switching mechanism housing, in which the switching mechanism unit is arranged and held captively therein. Furthermore, the switch comprises a switch housing, in which the switching mechanism housing is arranged and held captively therein, wherein the switch housing comprises a stationary contact part, which acts as a mating contact to the movable contact part. The switching mechanism housing comprises an electrically conductive first base body and the switching mechanism is configured so as, below a response temperature of the bimetallic snap-action disc, to keep the switch in a low-temperature position in which the switching mechanism establishes a first electrical connection via the movable contact part between the first base body and the stationary contact part, and, if the response temperature is exceeded, to bring the switch into a high-temperature position in which the switching mechanism interrupts the first electrical connection. The switch further comprises a PTC component, which is electrically connected parallel to the first electrical connection.

Claims

1. A temperature-dependent switch, comprising: a temperature-dependent switching mechanism having a switching mechanism unit, which comprises a movable contact part coupled to a bimetallic snap-action disc, and having a switching mechanism housing, in which the switching mechanism unit is arranged and held captively therein; and a switch housing, in which the switching mechanism housing is arranged and held captively therein, wherein the switch housing comprises a stationary contact part, which acts as a mating contact to the movable contact part; wherein the switching mechanism housing surrounds the switching mechanism unit from a first housing side, a second housing side opposite the first housing side, and a housing circumferential side extending between and transversely to the first and the second housing sides, wherein the switching mechanism housing on the first housing side comprises an opening through which the movable contact part interacts with the stationary contact part, wherein the switching mechanism housing comprises an electrically conductive first base body and the switching mechanism is configured so as, below a response temperature of the bimetallic snap-action disc, to keep the temperature-dependent switch in a low-temperature position in which the switching mechanism establishes a first electrical connection via the movable contact part between the first base body and the stationary contact part, and, if the response temperature is exceeded, to bring the temperature-dependent switch into a high-temperature position in which the switching mechanism interrupts the first electrical connection, and wherein the temperature-dependent switch further comprises a PTC component, which is electrically connected in parallel to the first electrical connection.

2. The temperature-dependent switch according to claim 1, wherein the PTC component is arranged in the switch housing.

3. The temperature-dependent switch according to claim 1, wherein the switch housing comprises an electrically conductive second base body, which is connected to the first base body via the PTC component, wherein the second base body surrounds the first housing side and the housing circumferential side of the switching mechanism housing.

4. The temperature-dependent switch according to claim 1, wherein the first housing side of the switching mechanism housing abuts the PTC component.

5. The temperature-dependent switch according to claim 1, wherein the first base body forms a part of the second housing side of the switching mechanism housing, wherein said part of the second housing side forms a freely accessible outside of the temperature-dependent switch.

6. The temperature-dependent switch according to claim 5, wherein said part of the second housing side of the switching mechanism housing which forms the freely accessible outside of the temperature-dependent switch comprises an outwardly arched, domed or pot-shaped portion.

7. The temperature-dependent switch according to claim 1, wherein the switching mechanism housing is integrally formed in one piece.

8. The temperature-dependent switch according to claim 3, comprising an insulator, which is arranged between the first base body and the second base body and which abuts the first base body and the second base body.

9. The temperature-dependent switch according to claim 8, wherein the insulator comprises an annular body, wherein an inner side of the annular body abuts the housing circumferential side of the switching mechanism housing, and wherein an outside of the annular body (50) abuts an inner circumferential surface of the switch housing.

10. The temperature-dependent switch according to claim 9, wherein an underside of the annular body abuts the PTC component.

11. The temperature-dependent switch according to claim 1, wherein a diameter of the opening is smaller than a diameter of the bimetallic snap-action disc measured parallel to the diameter of the opening.

12. The temperature-dependent switch according to claim 1, wherein the bimetallic snap-action disc is configured to snap over from a geometrically stable low-temperature configuration into a geometrically stable high-temperature configuration when the response temperature is exceeded, and wherein the bimetallic snap-action disc is supported in its high-temperature configuration on a supporting surface, which is arranged on the first housing side of the switching mechanism housing and is formed on the first base body, and thereby keeps the movable contact part at a distance from the stationary contact.

13. The temperature-dependent switch according to claim 1, wherein the switching mechanism unit further comprises a snap-action spring disc which is coupled to the movable contact part and is supported in the low-temperature position of the temperature-dependent switch on an internal surface arranged on the second housing side in an interior of the switching mechanism housing.

14. The temperature-dependent switch according to claim 1, wherein an intermediate space extending circumferentially between the switching mechanism housing and the switch housing is filled with insulating compound.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0067] FIG. 1 shows a schematic sectional view of the temperature-dependent switch according to an exemplary embodiment, the switch being shown in its low-temperature position; and

[0068] FIG. 2 shows a schematic sectional view of the switch shown in FIG. 1, the switch being shown in its high-temperature position.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0069] FIGS. 1-2 show an exemplary embodiment in each case in a schematic sectional view. The switch is identified therein in its entirety in each case by the reference number 100.

[0070] The switch 100 comprises a temperature-dependent switching mechanism 10, which is arranged in an electrically conductive switch housing 12.

[0071] The switching mechanism 10 comprises a functional switching mechanism unit 14 and a switching mechanism housing 16 surrounding said switching mechanism unit 14. The switching mechanism housing 16 at least partially surrounds the switching mechanism unit 14 from all six spatial directions.

[0072] As explained in detail below, the switching mechanism housing 16 is a partially open housing, and therefore the switching mechanism unit 14 is accessible from outside the switching mechanism housing 16 from at least one spatial direction, preferably from only one spatial direction.

[0073] Owing to the fact that the switching mechanism housing 16 at least partially surrounds the switching mechanism unit 14 from all six spatial directions, the switching mechanism unit 14 is held captively in the switching mechanism housing 16. The switching mechanism unit 14 therefore cannot be detached from the switching mechanism housing 16.

[0074] As long as the switching mechanism 10 is not installed in the switch 100 or its switch housing 12, there is preferably a certain clearance between the switching mechanism unit 14 and the switching mechanism housing 16. However, the switching mechanism unit 14 is firmly braced in the installed state of the switch 100 shown in FIG. 1. In the low-temperature position of the switch 100 that is shown in FIG. 1, the switching mechanism unit 14 is clamped between the switch housing 12 and the switching mechanism housing 16.

[0075] The switching mechanism unit 14 is constructed in three parts according to the present exemplary embodiment. The switching mechanism unit 14 comprises a temperature-dependent bimetallic snap-action disc 18, a temperature-independent snap-action spring disc 20 and a movable contact part 22. The bimetallic snap-action disc 18 and the snap-action spring disc 20 are held captively on the contact part 22. The switching mechanism unit 14 can thus be produced in advance as a semi-finished product and then inserted as a whole into the switching mechanism housing 16.

[0076] The switching mechanism 10 together with the switching mechanism unit 14 and the switching mechanism housing 16 also form a semi-finished product for the temperature-dependent switch 100 produced from it later on. Since the three components 18, 20, 22 of the switching mechanism unit 14 are connected captively to one other and the switching mechanism unit 14 is held captively in the switching mechanism housing 16, the switching mechanism 10 can be kept in stock as bulk material until it is installed in the temperature-dependent switch 100.

[0077] The switching mechanism housing 16 surrounds the switching mechanism unit 14 from a first housing side 24, from a second housing side 26 opposite the first housing side 24, and also from a housing circumferential side 28 extending between and transversely to the first and the second housing sides 24, 26.

[0078] Preferably, the switching mechanism housing 16 completely surrounds the switching mechanism unit 14 both from the second housing side 26 and from the housing circumferential side 28. The second housing side 26 and the housing circumferential side 28 thus preferably form closed housing sides of the switching mechanism housing 16. Only the first housing side 24 is a partially open housing side of the switching mechanism housing 16.

[0079] In other words, the housing circumferential side 28 surrounds the switching mechanism unit 14 along the entire circumference, i.e. from a total of four spatial directions oriented orthogonally with respect to one other. Furthermore, the switching mechanism housing 16 completely surrounds the switching mechanism unit 14 from a further spatial direction, namely from a spatial direction oriented orthogonally to the second housing side 26. Only from the sixth spatial direction, which is oriented orthogonally to the first housing side 24, does the switching mechanism housing 16 only partially surround the switching mechanism unit 14.

[0080] On the first housing side 24, the switching mechanism housing 16 comprises an opening 30 through which the movable contact part 22 is accessible from outside the switching mechanism housing 16. Through said opening 30 in the switching mechanism housing 16, the movable contact part 22 of the switching mechanism 10 interacts with a stationary contact part 32. The stationary contact part 32 is arranged on an inner side 34 of the switch housing 12.

[0081] In the exemplary embodiment shown in FIG. 1, the stationary contact part 32 is formed in one piece with the switch housing 12. In principle, however, it would also be possible to provide the stationary contact part 32 as a kind of rivet, which is connected as a separate component to the switch housing 12. An electrically conductive connection should be established between the switch housing 12 and the stationary contact part 32.

[0082] A diameter D1 of the opening 30 is smaller than a diameter D2, measured parallel thereto, of the bimetallic snap-action disc 18 and/or of the snap-action spring disc 20. Thus, although the movable contact part 22 is accessible from outside the switching mechanism housing 16 through the opening 30, the bimetallic snap-action disc 18 and the snap-action spring disc 20 cannot become detached from the switching mechanism housing 16 or emerge therefrom.

[0083] The switching mechanism housing 16 comprises a base body 36, which is formed from an electrically conductive material, for example, from metal. This base body 36 is referred to herein as the first base body. The electrically conductive first base body 36 forms the entire switching mechanism housing 16 in the exemplary embodiment shown here. In this exemplary embodiment, the switching mechanism housing 16 is thus formed in one piece from an electrically conductive material.

[0084] An upper part of the first base body 36, which forms the second housing side 26, simultaneously forms a freely accessible outside of the switch 100. The first housing side 24 and the housing circumferential side 28 are arranged completely within the switch housing 12 and are therefore not accessible from outside the switch 100.

[0085] The switch housing 12 consists of an electrically conductive second base body 38. The second base body 38 is preferably also composed of metal. The second base body 38 forms the lower part of the switch 100, in which the remaining components of the switch 100 are arranged.

[0086] The second base body 38 is preferably pot-shaped. An upper edge 40 of the raised, circumferential wall 42 of the second base body 38 of the switch housing 12 is folded over or crimped towards the centre of the switch 100 so that the switching mechanism 10 is held captively in the switch housing 12. The intermediate space running circumferentially between the switching mechanism housing 16 and the switch housing 12 is filled with an insulating compound 44. The insulating compound 44 is preferably an impregnating varnish, which is poured into the intermediate space between the switch housing 12 and the switching mechanism housing 16 at the end of the installation of the switch 100.

[0087] The insulating compound 44 ensures, on the one hand, that the switching mechanism housing 16 is fixed in the switch housing 12. On the other hand, the insulating compound 44 ensures a mechanical seal that prevents liquids or contaminants from entering the inside of the switch 100 from the outside. This results in a sealed switch housing 12, in which the switching mechanism housing 16 is held captively.

[0088] A PTC component 46 is furthermore arranged in the switch housing 12. Said PTC component 46 is a PTC thermistor material, the electrical resistance of which increases as the temperature increases. The PTC component 46 has the form of a plate or disc. The PTC component 46 is inserted into the switch housing 12 and surrounds the stationary contact part 32.

[0089] The switching mechanism housing 16 rests with its first housing side 24 flat on the PTC component 46. The electrically conductive first base body 36 of the switching mechanism housing 16 is thus connected via the PTC component 46 to the electrically conductive second base body 38 of the switch housing 12.

[0090] An insulator 48 rests on the PTC component 46. Said insulator 48 is an annular body 50, which is arranged between the first base body 36 of the switching mechanism housing 16 and the second base body 38 of the switch housing 12 and lies on the two basic bodies 36, 38. More specifically, the annular body 50 of the insulator 48 lies with its inner side 52 on the housing circumferential side 28 of the switching mechanism housing 16 and lies with its outer side 54 on an inner circumferential surface 56 of the switch housing 12.

[0091] The insulator 48 is preferably a plastics insulator. In addition to its function of insulating the housing circumferential side 28 of the switching mechanism housing 16 from the inner circumferential surface 56 of the switch housing 12, the insulator 48 also ensures a correct alignment of the switching mechanism 10 relative to the switch housing 12 or the switching mechanism 10 relative to the stationary contact part 32. The shape of the annular body 50 of the insulator 48 is preferably adapted to the shape of the switch housing 12. The annular body 50 is therefore preferably a circular ring.

[0092] Since the second base body 38 of the switch housing 12 and the first base body 36 of the switching mechanism housing 16 are each made of electrically conductive material, thermal contact can be made via their outer surfaces to a device to be protected.

[0093] The outer surfaces of the two basic bodies 36, 38 also serve at the same time for the electrical connection of the switch 100. For example, the outside 58 of the second base body 38 of the switch housing 12 can thus act as a first electrical connection and the outside 60 of the first base body 48 of the switching mechanism housing 16 can act as a second electrical connection. More specifically, the outside 60 of that part of the base body 38 of the switching mechanism housing 16 which protrudes from the switch housing 12 can act as a second electrical connection.

[0094] Said part of the switching mechanism housing 16, which forms a freely accessible outside of the switch 100, comprises a domed portion 62 in the exemplary embodiment shown here. Said domed portion 62, the upper side of which is convex, ensures an extremely pressure-stable design of the switch 100. Instead of a domed portion 62, this portion of the switching mechanism housing 16 may also be pot-shaped.

[0095] In the low-temperature position of the switch 100 that is shown in FIG. 1, the temperature-independent snap-action spring disc 20 is in its first configuration and the temperature-dependent bimetallic snap-action disc 18 is in its low-temperature configuration. The snap-action spring disc 20 presses the movable contact part 22 against the stationary contact part 32, which acts as a mating contact. The switch 100 is thus in its closed position, in which an electrically conductive connection between the outside 60 of the switching mechanism housing 16 and the outside 58 of the switch housing 12 is produced via the snap-action spring disc 20, the movable contact part 22 and the stationary contact part 32.

[0096] The contact pressure between the movable contact part 22 and the stationary contact part 32 is produced by the snap-action spring disc 20. The snap-action spring disc 20 is supported in the low-temperature position of the switch 100 on an internal surface 64 arranged on the second housing side 26 in the interior of the switching mechanism housing 16. In this state, by contrast, the bimetallic snap-action disc 18 is mounted virtually without any force in the switching mechanism housing 16.

[0097] If the temperature of the device to be protected and thus the temperature of the switch 100 and of the bimetallic snap-action disc 18 arranged therein now increases to the switching temperature of the bimetallic snap-action disc 18 or above this switching temperature, the bimetallic snap-action disc 18 snaps over from its concave low-temperature configuration shown in FIG. 1 into its convex high-temperature configuration shown in FIG. 2. During said snapping-over, the bimetallic snap-action disc 18 is supported with its outer edge 66 on a supporting surface 68 arranged on the first housing side 24 of the switching mechanism housing 16. This means that the snap-action spring disc 20 is simultaneously deflected upwards at its centre such that the snap-action spring disc 20 snaps over from its first stable geometric configuration shown in FIG. 1 into its second geometrically stable configuration shown in FIG. 2.

[0098] FIG. 2 shows the high-temperature position of the switch 100, in which the latter is open. The electrically conductive connection between the switch housing 12 and the switching mechanism housing 16, which is undertaken in the low-temperature position of the switch 100 via the switching mechanism unit 14, is interrupted in the high-temperature position of the switch 100 that is shown in FIG. 2. The switch housing 12 is then only still connected to the switching mechanism housing 16 via the PTC component 46.

[0099] In the high-temperature position of the switch 100, the PTC component 46 already has a relatively high electrical resistance because of the high temperature. Thus, only a small residual current from the electrically conductive switch housing 12 can flow via the PTC component 46 into the electrically conductive switching mechanism housing 16. This residual current is harmless to the device to be protected. However, the residual current causes the PTC component 46 to heat up, as a result of which the entire switch 100 is heated up. Thus, the bimetallic snap-action disc 18 is also kept at a temperature above its switching temperature, and therefore the switch 100 is no longer closed via the switching mechanism unit 14.

[0100] Only when the device to be protected is de-energized, i.e. when there is no more current flowing via the switch 100, does the PTC component 46, and thus the entire switch 100, cool down. As soon as the switching mechanism unit 14 then reaches a temperature below the response temperature of the bimetallic snap-action disc 18, the bimetallic snap-action disc 18 then snaps over again from its high-temperature configuration shown in FIG. 2 into its low-temperature configuration shown in FIG. 1, as a result of which the switch 100 is closed again.

[0101] Finally, it should be noted that the snap-action spring disc 20 is not absolutely necessary. The switching mechanism unit 14 can also be realized without a snap-action spring disc 20. In such a case, the switching mechanism unit 14 then only comprises the bimetallic snap-action disc 18 and the movable contact part 22. The bimetallic snap-action disc 18 then not only ensures the switching behaviour of the switch 100, but also simultaneously generates the contact pressure between the movable contact part 22 and the stationary contact part 32 in the low-temperature position of the switch 100. The bimetallic snap-action disc 18 is then thus used as a live component of the switching mechanism 10.