Casing and sealed switching device for a temperature-dependent switch - Patents.com

Abstract

To provide an improved casing for receiving a temperature-dependent switch, in a hermetically sealed manner.SOLUTION: A switch (10) switches between a closed state where the switch establishes an electrically conductive connection between a first external terminal (48) and a second external terminal (50), and an open state where the switch disconnects the electrically conductive connection. A casing includes: a first casing part (52) made of metal; a second casing part (54) made of a metal which is connected to the first casing part via a material-locking connection comprising an insulated connection material part (64); a receptacle surrounded partially by the first casing part and the second casing part; a first connection lead (72) penetrating through the insulated connection material part (64), including, at one end portion, a first connection surface (68) arranged in the receptacle, and connected to the first external terminal (48); and a second connection lead (74) including, at one end portion, a second connection surface (70), and connected to the second external terminal (50) of the temperature-dependent switch.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a casing for hermetically sealing a temperature dependent switch.The present invention also relates to a sealed switching device comprising the casing and a temperature dependent switch disposed therein. [Background technology]

[0002] An exemplary temperature-dependent switch is disclosed in German Patent Publication No. 37 33 693, which also discloses a casing for receiving the temperature-dependent switch in a hermetically sealed manner.

[0003] Such temperature dependent switches are primarily used in a known manner to monitor the temperature of a device, by being in direct or indirect thermal contact with the device to be protected, so that the temperature of the device to be protected affects the temperature of a switching mechanism located inside the switch.

[0004] The switch is typically connected electrically in series with the supply circuit of the device to be protected via a connecting cable, so that the supply current of the protected device flows through the switch below the response temperature of the switching mechanism.

[0005] Such a temperature-dependent switch includes a temperature-dependent switching mechanism that is enclosed in a switch housing and that opens or closes a conductive connection between two external terminals of the switch depending on its temperature. More precisely, the temperature-dependent switching mechanism is configured to switch between a closed state and an open state in a temperature-dependent manner, such that in the closed state, the temperature-dependent switching mechanism is assumed to be below a response temperature and establishes a conductive connection between the two external terminals, and in the open state, the temperature-dependent switching mechanism is assumed to be above a response temperature and interrupts the conductive connection.

[0006] To enable the above-mentioned temperature dependent switching function, the temperature dependent switching mechanism disposed inside the switch housing typically comprises a bimetallic portion which, upon reaching a response temperature, rapidly transforms from its cold state to its hot state, thereby lifting and disengaging a movable contact, disposed on a device movable relative to the switch housing, from a fixed contact, which is typically disposed in a fixed position inside the switch housing and electrically connected to one of the two external terminals of the switch, while the movable contact interacts via either the bimetallic portion or a spring portion associated with the bimetallic portion.

[0007] In a temperature-dependent switch, such as that disclosed in German Patent Publication No. 198 27 113, the bimetallic part is provided as a bimetallic disc which is coupled to a current-carrying element and which, in the closed state of the switching mechanism, electrically connects two fixed contacts arranged on a cover part of the switch housing to one another, and, in the open state of the switching mechanism, lifts the current-carrying element away from the two fixed contacts and interrupts the conductive connection therebetween.

[0008] For certain applications, such switches must be equipped with special seals, usually in addition to the switch's conventional housing. This is necessary, for example, when such temperature-dependent switches are used in corrosive or explosive environments, or when the switches are inserted into environments where they are exposed to relatively high external pressures.

[0009] In the above mentioned applications, it may be required for safety reasons that the temperature dependent switch is hermetically gas-tight or hermetically sealed.

[0010] In the switch disclosed in the aforementioned German Patent Publication 37 33 693, this problem is solved by inserting the switch into a further metal housing. The further metal housing is provided with a separate cover, also made of metal, which is welded to the metal housing after the switch has been inserted. This cover is provided with a pressure-resistant glass feedthrough made of glass, through which the switch's connection cable is routed from the inside to the outside. After the switch has been inserted, but before the metal housing is hermetically sealed, the metal housing is flushed with an inert gas, preferably helium or nitrogen, and if necessary filled with this gas. The connection cable is usually laser-welded, and the pressure-resistant glass feedthrough is fused to the metal housing.

[0011] In this manner, the hermetically sealed temperature switch can be configured to be extremely pressure resistant and suitable for use in corrosive and potentially explosive environments.

[0012] However, the method for manufacturing the sealed temperature switch disclosed in German Patent Publication 37 33 693 A1 has several disadvantages. First, manufacturing the hermetically sealed switch described therein requires a high level of manual labor. Furthermore, the temperature-dependent switching mechanism located inside the switch housing can be damaged when closing the metal housing or installing the glass pressure-glass feedthrough. Such glass melting results in extremely high temperatures during its manufacture. However, typical temperature-dependent switching mechanisms inserted inside the switch can typically be exposed to temperatures up to 200°C to 500°C without damaging the bimetallic parts inserted therein. Summary of the Invention [Problem to be solved by the invention]

[0013] It is therefore an object of the present invention to provide an improved casing for receiving a temperature dependent switch in a hermetically sealed manner, which casing is as simple as possible to manufacture, allows for automated handling, and preferably does not require exposure to critical (high) temperatures in order to seal the switch together with the switching mechanism. [Means for solving the problem]

[0014] According to the invention, this object is solved by a casing according to claim 1, which comprises the following components: a first casing portion made of metal; a second casing part made of metal, connected to the first casing part by a hermetically sealed material locking connection part including an electrically insulated connection material part; a receiving part for receiving the temperature dependent switch in a hermetically sealed manner and being at least partially surrounded by the first casing part and the second casing part; a first connection lead that is led through the electrically insulated connection material portion, has a first connection surface disposed in the receiving portion at one end, and is electrically connected to a first external terminal of the temperature-dependent switch; and a second connection lead that is led through the electrically insulated connection material portion, has a second connection surface at one end that is positioned within the receiving portion, and is electrically connected to a second external terminal (50) of the temperature-dependent switch.

[0015] The casing according to the present invention thus has a multi-component structure, including a first metallic casing part, a second metallic casing part, and an electrically insulated connecting material that connects the two casing parts in a material-locking and gas-tight manner. In contrast to the encapsulated temperature-dependent switch disclosed in German Patent Publication No. 37 33 693, the two casing parts are not welded to each other but are connected to each other by an electrically insulated connecting material through which two connecting leads also pass. Thus, according to the present invention, the electrically insulated connecting material not only serves to route the two connecting leads and electrically insulate them from each other, but also to create a gas-tightly sealed connection between the two metal casing parts. This has various advantages.

[0016] One advantage of the casing according to the present invention is that the casing with its two casing sections can be pre-manufactured as a semi-finished product, i.e., before the switch is inserted into the casing. This greatly simplifies final assembly, as the final step is simply to insert the switch into the pre-manufactured casing and seal it. This final step can include the production of connections by welding, melting, or soldering, which can be easily automated.

[0017] It is particularly advantageous if the hermetically sealed, electrically insulating connection material between the first and second housing parts is established in advance, i.e., before the switch is inserted. The melting process typically required for this generates very high temperatures, but this does not affect the switch itself, since the switch is inserted into the housing only after the melting process. Therefore, the switching mechanism of the switch is not damaged. This is a significant difference from, for example, German Patent Publication 37 33 693, in which a pressurized glass seal made of hot glass is created only after the switch is inserted into the metal housing.

[0018] However, in the device according to the invention, this melting process can already be carried out in advance, since the two connection leads are led from the inside to the outside through the same electrically insulated connection material, thereby connecting the two housing parts in a material-locked manner. Each of these two pre-integrated connection leads terminates at a first end in connection surfaces (called in this case the first and second connection surfaces) arranged in the receptacle, which connection surfaces are used for electrical connection to the two external terminals of the temperature-dependent switch.

[0019] The receptacle preferably includes a recess into which the temperature-dependent switch can be inserted. The two connection surfaces are located within this recess, so that when the temperature-dependent switch is inserted into the recess / receptacle, it automatically rests on the two connection surfaces with its two external terminals. This makes the electrical connection of the switch very simple, preferably automated, and cost-effective, despite the insertion of the switch into the casing.

[0020] The two connection leads, which are led through the electrically insulating connection material and integrated into the casing, preferably each have a second end that is arranged outside the receiving part, i.e. that is led outwards, so that corresponding lines can be very simply connected to the second ends of the two connection leads, respectively, so that the casing, and thus the temperature-dependent switch arranged therein, can be connected in a corresponding manner to the device to be protected.

[0021] In a refinement, the electrically insulating connection material comprises glass. According to this refinement, the hermetically sealed, material-locked, electrically insulating connection between the first and second casing parts comprises a glass-to-metal seal.

[0022] Such a glass-to-metal seal allows, on the one hand, an electrically insulated connection between the two casing parts and, on the other hand, a gas-tightly sealed connection between these two casing parts.

[0023] Such a glass-to-metal seal allows for a hermetically sealed connection that meets the requirements of DIN EN (German National Standard) 60079-15. According to this, a hermetically sealed connection or a hermetically sealed device is understood to mean a connection / device that is configured so that it cannot be opened and that is effectively sealed by melting so that the ingress of the outside atmosphere is prevented. Preferably, such a hermetically sealed connection allows for a vacuum-tight connection between the first and second casing parts.

[0024] As used herein, the terms "airtight" or "hermetically sealed" refer to an airtight connection or seal that prevents the exchange of materials from the inside to the outside and vice versa. Generally, such an airtight closure is determined by a helium leak detector. -7 Leak rates of less than mbar·l / s. Achieving such hermetically sealed devices / connections according to DIN EN 60079-15 is generally only possible by fusing metal to metal or glass to metal.

[0025] Therefore, in a preferred refinement, the glass-to-metal connection between the first and second casing parts comprises glass fused to the first and second casing parts, the fused connection preferably being a fused connection extending along a closed contour, for example an annular contour, so that a hermetically sealed space can be created inside the casing.

[0026] In a further refinement, the casing further comprises a third casing part made of an electrically insulating material arranged between the first casing part and the first connection lead.

[0027] Preferably, this third casing part is also arranged between the first casing part and the second connection lead, the third casing part providing electrical insulation between the two connection leads and the first casing part, the first casing part also being electrically conductive due to its metallic nature.

[0028] Preferably, this third casing part is made of ceramic.

[0029] The third casing part is preferably inserted in particular into the first casing part.

[0030] In a further refinement, the casing further comprises a fourth casing part made of an electrically insulating material arranged between the second casing part and the first connection lead.

[0031] The fourth casing part is preferably also disposed between the second casing part and the second connection lead. The fourth casing part preferably serves to electrically insulate the second casing part from the two connection leads. In particular, the fourth casing part preferably also serves to electrically insulate the two connection leads from the conductive parts of the switch housing of the temperature-dependent switch inserted into the receptacle. Like the third casing part, the fourth casing part is preferably also made of ceramic.

[0032] In the fourth casing part, an electrically insulated connecting material part is provided to connect the first casing part, the second casing part, the third casing part and the fourth casing part to each other.

[0033] The four casing sections of this modification are preferably secured to one another by electrically insulating connecting material, preferably made of glass. In other words, the connecting material used to connect the first and second casing sections also simultaneously secures the third and fourth casing sections within the casing. Thus, all four casing sections can be secured to one another by the connecting material, i.e., before the switch is inserted into the casing receptacle.

[0034] In a further refinement, the third casing part contacts a first side of the first connection lead and the fourth casing part contacts a second side of the first connection lead.

[0035] According to this refinement, it is also preferred that the third casing part contacts a first side of the second connection lead and the fourth casing part contacts a second side of the second connection lead opposite the first side.

[0036] Two casing parts made of electrically insulating material, referred to herein as the third casing part and the fourth casing part, are preferably in contact on both sides with two connection leads integrated into the casing. In this way, these two casing parts electrically insulate the other metallic casing parts (referred to as the first and second casing parts), electrically insulate the two connection leads, and also function as static support parts for the casing, increasing the mechanical stability of the casing. Because ceramic is an ideal electrical insulator and a mechanically strong material, improvements in the third and fourth casing parts made of ceramic are also advantageous for this reason.

[0037] In a further refinement, the first casing part at least partially surrounds the second casing part, and in particular preferably the first casing part at least partially surrounds the second casing part, the third casing part and the fourth casing part.

[0038] The first casing part forms the outermost shell of the casing, so to speak. The first casing part is preferably substantially pot-shaped. The second casing part and the fourth casing part are preferably ring-shaped. The third casing part is preferably substantially plate-shaped and inserted into the first casing part.

[0039] The annular configuration of the second and / or fourth casing part allows for a space-saving arrangement of the casing according to the invention. "Annular" in this sense does not necessarily mean circular, but may also have a circular, angular or prismatic closed contour.

[0040] In a further refinement, the two connection surfaces lie within a common connection surface.

[0041] The casing according to the invention is therefore particularly suitable for receiving and hermetically sealing temperature-dependent switches whose external terminals are in one plane, and according to this refinement, such switches can be electrically connected very easily to the two connection leads of the casing according to the invention by arranging their two external terminals in the connection plane.

[0042] As already mentioned, the present invention relates to a casing having a temperature dependent switch disposed therein, as well as the casing itself (without a temperature dependent switch inserted therein). A casing with a switch inserted therein is referred to herein as an "encapsulated switching device."

[0043] In a preferred refinement, the temperature-dependent switch has a temperature-dependent switching mechanism and a switch housing in which the switching mechanism is arranged, and the first external terminal and the second external terminal are arranged on the switch housing.

[0044] It is preferable that the switch housing comprises a lower portion made of a conductive material and a cover portion made of an electrically insulating material that closes the lower portion, and that the first external terminal and the second external terminal are arranged on the cover portion.

[0045] In a further refinement, it is provided that the casing comprises a fourth casing part made of an electrically insulating material, the fourth casing part being arranged annularly around the switch housing and electrically insulating the first connecting lead from the lower part.

[0046] Preferably, the fourth casing portion lies against the circumference of the lower part of the switch housing to ensure that the switch housing is centrally located.

[0047] In a further refinement, the switch housing is connected to the second casing part in a material-locking manner.

[0048] This material-locking connection is also preferably implemented as a hermetically sealed connection involving a metal fusion, for example, by welding or soldering. However, since this material-locking connection is made directly on the switch housing, it can only be made after the switch has been inserted into the casing. Therefore, it is important to ensure that this generates as little heat as possible to prevent damage to the switching mechanism located inside the switch housing.

[0049] As an alternative refinement, the casing may further comprise a fifth casing part made of metal, which closes the second casing part on at least one side and is fixed to the second casing part in a material-locking manner.

[0050] Preferably, this material-locking connection also constitutes a gas-tightly sealed connection in the sense described above. Compared to a direct material-locking connection between the switch housing and the second casing part, this variant has the advantage that no material-locking connection is made directly to the switch housing itself, which further has the effect of being particularly gentle on the switching mechanism arranged inside the switch housing.

[0051] It is to be understood that the features mentioned above and those to be described below can be used not only in the combinations shown in each case, but also in other combinations and alone, without departing from the scope of the invention. [Brief explanation of the drawings]

[0052] Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. [Figure 1] 1 is a schematic cross-sectional view of an exemplary temperature dependent switch that may be mounted within a casing according to the present invention, the switch being in its cold state; [Figure 2] 2 is a schematic cross-sectional view of the switch shown in FIG. 1, the switch being in its hot state; [Figure 3] 1 is a schematic cross-sectional view of a first embodiment of a casing according to the invention, without a switch inserted therein; [Figure 4] 4 is a schematic cross-sectional view of the casing of FIG. 3 with a switch inserted therein; [Figure 5] 3 is a schematic cross-sectional view of a second embodiment of a casing according to the invention, with a switch inserted therein; DETAILED DESCRIPTION OF THE INVENTION

[0053] 1 and 2 illustrate an exemplary temperature dependent switch, generally designated 10, that may be inserted into and hermetically sealed by a casing according to the present invention.

[0054] Figure 1 shows the switch 10 in a cold state, and Figure 2 shows the switch 10 in a hot state.

[0055] It should be understood that the switch 10 shown in Figures 1 and 2 is only one example of various possible temperature-dependent switches that can be inserted into a casing according to the present invention and hermetically sealed against gas leakage by the device. As can be seen particularly from Figures 3-5, the casing of the present invention is, in principle, suitable for receiving switches of different configurations. However, the switch 10 shown in Figures 1 and 2 will be described below as an example of a possible temperature-dependent switch in order to explain the basic structure and function of such a temperature-dependent switch.

[0056] Switch 10 includes a switch housing 12 within which is disposed a temperature dependent switching mechanism 14. Switch housing 12 includes a pot-shaped lower portion 16 and a cover portion 18, which is retained to lower portion 16 by a folded or flanged upper edge 20 of lower portion 16. In the example of switch 10 shown in Figures 1 and 2, lower portion 16 is made of an electrically conductive material, preferably metal. Cover portion 18 is made of an electrically insulating material, such as plastic or ceramic.

[0057] A ring 22 is disposed between the lower portion 16 and the cover portion 18 and rests against a shoulder 24 on the lower portion 16. The ring 22 is preferably made of an electrically insulating material, such as, for example, plastic or ceramic.

[0058] The switching mechanism 14 comprises a temperature-independent spring disk 26, the outer periphery of which is located between the shoulder 24 of the lower part 16 and the ring 22. In addition to the spring disk 26, the switching mechanism 14 comprises a temperature-dependent bimetallic part 28 configured as a bimetallic disk, which is centrally engaged with the spring disk 26 by a pin-shaped rivet 30, by means of which the spring disk 26 and the bimetallic disk 28 are mechanically connected to a current-transmitting member in the form of a contact plate 32.

[0059] The rivet 30 includes a first shoulder 34 against which the bimetal disc 28 seats with its inner edge. The inner edge of the bimetal disc 28 preferably rests with radial and axial play on this first shoulder 34 of the rivet 30. The rivet further includes a second shoulder 36 on which the spring disc 26 rests, more preferably with radial and axial play.

[0060] On its upper side facing the cover part 18, the current carrying member 32 has two interconnected contact surfaces 38a, 38b which interact with fixed contact parts 40, 42 which are the inner heads of rivets 44, 46 which engage through the cover part 18 and whose outer heads form the external terminals 48, 50 of the switch 10.

[0061] 1, the spring disc 26 and the bimetal disc 28 press the current carrying member 32 with its two contact surfaces 38a, 38b against the fixed contacts 40, 42. In this switched state of the switch 10, the switching mechanism 14 thus establishes a conductive connection between the first external terminal 48 and the second external terminal 50.

[0062] Starting from the closed state of switch 10 shown in FIG. 1, if the temperature of switch 10 increases, thereby increasing the temperature of bimetallic disc 28, bimetallic disc 28 will snap from its convex position shown in FIG. 1 to its concave position shown in FIG. 2, whereby bimetallic disc 28 will position its outer periphery in the region of shoulder 24 of bottom side 26 or lower portion 16 of the spring disc, thereby pulling current carrying member 32 downward with its center against the force of spring disc 26. This causes contact surfaces 38a, 38b of current carrying member 32 to lift from two fixed contacts 40, 42, opening switch 10. In the open state of switch 10 shown in FIG. 2, the conductive connection between two external terminals 48, 50 of switch 10 is thus interrupted.

[0063] Thus, the temperature dependent switching mechanism 14 of the switch 10 is configured to establish and break a conductive connection between the two external terminals 48, 50 in a temperature dependent manner. Below the response temperature of the bimetallic disc 28, the switching mechanism 14 is in its cold state shown in Figure 1, in which it establishes a conductive connection between the two external terminals 48, 50. As soon as the response temperature of the bimetallic disc 28 is exceeded, the bimetallic disc 28 places the switching mechanism 14 in the hot state shown in Figure 2, in which it breaks the conductive connection between the two external terminals 48, 50. Subsequent further cooling of the bimetallic disc 28 below its response temperature places the switching mechanism 14 again in the cold state shown in Figure 1, in which the switch 10 is again closed.

[0064] 3 shows a first embodiment of a casing according to the invention in a schematic cross-sectional view, without a switch inserted therein. The casing is generally designated 100.

[0065] The casing 100 serves to receive the switch 10 and acts as a kind of enclosure that further surrounds the switch housing 12 of the switch 10. The casing 100 containing the inserted switch 10 is referred to herein as an "enclosed switching device." The casing 100 includes a substantially pot-shaped first casing portion 52. A second casing portion 54, a third casing portion 56, and a fourth casing portion 58 are disposed within the first casing portion 52. The first casing portion 52 and the second casing portion 54 are preferably made of metal. The third casing portion 56 and the fourth casing portion 58 are made of an electrically insulating material, preferably ceramic.

[0066] The third casing part 56 and the fourth casing part 58 are used for electrical insulation.

[0067] The two casing parts 54, 58 are essentially ring-shaped. Therefore, they form a circumferentially closed contour. Each of the two casing parts 54, 56 is configured as a type of profile ring. The second casing part 54 is preferably supported by and directly disposed on the fourth casing part 58. The third casing part 56 rests on the inner base 60 of the first casing part 52. The outer diameter of the third casing part 56 corresponds approximately to the inner diameter of the first casing part 52, so that the third casing part 56 is preferably inserted into the first casing part 52 with a precise fit. The upper side of the third casing part 56 has an outer profile with at least two recesses 62a, 62b.

[0068] The two metal casing parts 52, 54 are connected to one another in a gas-tight, electrically insulating manner by a connecting material 64. The connecting material 64 preferably comprises glass, which provides a hermetically sealed, material-locked, electrically insulated connection between the two casing parts 52, 54. The hermetically sealed, material-locked connection is configured as a fusion connection made of glass, which is a hermetically sealing glass-to-metal seal that meets the gas-tight requirements specified in DIN EN 60079-15.

[0069] The hermetically sealed connection between the two casing parts 52, 54 is preferably produced by laser welding. The hermetically sealed connection extends along a closed annular contour, thus hermetically sealing the space between the two casing parts 52, 54 along the entire circumference. At the same time, the third casing part 56 and the fourth casing part 58 are also connected to the two metal casing parts 52, 54 by this glass connection. The four casing parts 52, 54, 56, 58 of the casing 100 therefore form an inseparably connected unit.

[0070] Inside the casing 100, the casing parts 52, 54, 56, 58 together form a recess forming a cavity suitable as a receptacle 66 for the temperature-dependent switch 10 to be inserted therein. The receptacle 66 is provided with two connection surfaces 68, 70, which serve to electrically connect the switch 10. When the switch 10 is inserted, the two connection surfaces 68, 70 are in contact with the two external terminals 48, 50. The first connection surface 68 is in contact with the first external terminal 48 of the switch 10. The second connection surface 70 is in contact with the second external terminal 50 of the switch 10. Thus, when inserted, the switch 10 is inserted "upside down" into the receptacle 66 (see FIG. 4). To improve electrical contact and secure the switch 10 in place, the two connection surfaces 68, 70 are preferably connected to the respective external terminals 48, 50 in a material-locking manner (e.g., by soldering or welding).

[0071] The two connection surfaces 68, 70 arranged in the receiving part 66 are electrically connected to respective external terminals 76, 78 of the casing 100 via respective connection leads 72, 74. The two connection leads 72, 74 extend through an electrically insulated connection material (glass) 64 that connects the two metal casing parts 52, 54 to each other in a material-locking manner. In other words, the two connection leads 72, 74 are routed to the outside by this connection material 64.

[0072] Each of the two connection leads 72, 74 is disposed between the two electrically insulated casing parts 56, 58 adjacent to the respective connection surfaces 68, 70. The third casing part 56 contacts the bottom surface of each of the connection leads 72, 74. The fourth casing part 58 contacts the two connection leads 72, 74 from the opposite top side 82.

[0073] However, it is understood that the two casing sections 56, 58 made of an electrically insulating material are not necessarily required for the structure of the casing 100. In particular, these two casing sections 56, 58 can be dispensed with if the two connection leads 72, 74 are covered with an electrically insulating material. However, providing the two casing sections 56, 58 has the advantage of increasing the mechanical stability of the casing 100. In particular, the fact that the two connection leads 72, 74 pass through the recesses 62a, 62b provided in the third casing section 56, in which the fourth casing section 58 is also disposed, contributes positively to the stabilization of the casing 100. Since the fourth casing section 58 is preferably an annular component, it is desirable that the two recesses 62a, 62b are connected to each other. In this way, the two recesses 62a, 62b are preferably annular in shape. However, it is understood that the two connection leads 72, 74 are not annular in shape and do not contact each other.

[0074] 4 shows a schematic of how switch 10 can be inserted into receptacle 66 of casing 100. Switch 10 is inserted into receptacle 66 "upside down," meaning that bottom portion 16 of switch 10 points upward and cover portion 18 of switch 10 points downward, toward the bottom of receptacle 66.

[0075] When inserted into the receptacle 66, the switch 10 rests with its first external terminal 48 against the first connection surface 68 and its second external terminal 50 against the second connection surface 70. As already mentioned, the two external terminals 48, 50 are preferably fixed to their respective connection surfaces 68, 70 in a materially locked manner.

[0076] To hermetically seal the switch 10 with the casing 100, the switch 10 is fused to the second casing part 54 after its lower part 16, preferably made of metal, is inserted into the receptacle 66. According to the embodiment shown in FIG. 4, this is done by a fusion joint 84 made by welding or soldering, which connects the lower part 16 of the switch 10 to the second casing part 54 in a material-locking manner along a closed circumferential contour. This material-locking connection between the second casing part 54 and the lower metal part 16 of the switch 10 also forms a hermetically sealed connection. Therefore, all points where atmospheric exchange can occur between the interior of the switch and the external atmosphere surrounding the casing 100 are hermetically sealed.

[0077] The second casing part 54 is fused directly to the switch 10, and the two metal casing parts 52, 54 are hermetically sealed to prevent gas leakage with the aid of the connecting material 64. Thus, atmospheric air cannot escape from the interior of the switch 10, nor can atmospheric air penetrate into the interior of the switch 10 from the outside. Since the two connecting leads 72, 74 are led to the outside by the connecting material 64, the switch 10 can be electrically connected to the device to be protected in a simple manner, even after it has been inserted into the casing 100. For this purpose, only the corresponding connecting lines 86, 88 need to be connected to the two external terminals 76, 78 of the casing 100.

[0078] For further sealing and mechanical stabilization, the switch 10 fixed in the casing 100 may be further covered with a resin cover 90 .

[0079] Figure 5 shows a second embodiment of the casing 100. The basic structure of the casing 100 does not differ from the first embodiment shown in Figure 4. However, here the second casing part 54 is no longer directly connected to the bottom part 16 of the switch 10 in the inserted state.

[0080] In the second embodiment shown in Fig. 5, the casing 100 further comprises a fifth casing part 92, which serves as a kind of cover for closing the second casing part 54. The fifth casing part 92 is also made of metal. The fifth casing part 92 closes the second casing part 54 at its upper side and is connected to the second casing part 54 by a material bond. For this purpose, a welded joint 94, which is preferably configured as a circumferential welded joint, is provided. Thus, in this embodiment, the interior of the casing 100, which serves as the receiving part 66 of the switch 10, is also hermetically sealed.

[0081] Again, the plastic cap 90 provides additional sealing.

[0082] Both embodiments of the casing 100 shown here ensure a hermetic sealing or encapsulation of the switch 10, whereby the switching mechanism 14, located inside the switch housing 12, is encapsulated in a gas-tight manner toward the outside. The interfaces between the individual casing sections 52, 54 and 54, 92, and the interface between the second casing section 54 and the switch lower section 16, respectively, are typically realized by sealed fusion connections, which are configured as metal-to-metal or glass-to-metal fusion connections. Despite the hermetic encapsulation within the casing 100, the switch 10 can still be electrically connected in a simple manner.

[0083] Due to the modular construction of the casing 100, it is suitable for hermetically sealing temperature-dependent switches of various constructions. However, the casing 100 according to the invention is preferably used to seal switches whose external terminals 48, 50 lie in a common connection plane E.

Claims

1. A casing (100) for a temperature-dependent switch (10), the temperature-dependent switch (10) being configured to switch between a closed state and an open state in a temperature-dependent manner, wherein in the closed state the temperature-dependent switch (10) establishes a conductive connection between a first external terminal (48) and a second external terminal (50), and in the open state the temperature-dependent switch (10) breaks the conductive connection, the casing (100) comprising: a first casing portion (52) made of metal; a second casing part (54) made of metal, connected to the first casing part (52) by a hermetically sealed connection part including an electrically insulated connection material part (64); a receiving portion (66) for receiving the temperature dependent switch (10) in a hermetically sealed manner and being at least partially surrounded by the first casing portion (52) and the second casing portion (54); a first connection lead (72) that is led through the electrically insulated connection material portion (64), has a first connection surface (68) disposed within the receiving portion (66) at one end, and is electrically connected to the first external terminal (48) of the temperature-dependent switch (10); and a second connection lead (74) that is led through the electrically insulated connection material portion (64), has a second connection surface (70) at one end that is arranged in the receiving portion (66), and is electrically connected to a second external terminal (50) of the temperature-dependent switch.

2. 2. The casing of claim 1, wherein the electrically insulating connecting material comprises glass.

3. 2. The casing of claim 1, further comprising a third casing portion (56) disposed between the first casing portion (52) and the first connecting lead (72), the third casing portion (56) being made of an electrically insulating material.

4. 2. The casing of claim 1, further comprising a fourth casing portion (58) disposed between the second casing portion (54) and the first connecting lead (72), the fourth casing portion (58) being made of an electrically insulating material.

5. 2. The casing of claim 1, further comprising a third casing portion (56) made of an electrically insulating material and disposed between the first casing portion (52) and the first connection lead (72), and a fourth casing portion (58) made of an electrically insulating material and disposed between the second casing portion (54) and the first connection lead (72), wherein an electrically insulating connecting material portion (64) interconnects the first casing portion (52), the second casing portion (54), the third casing portion (56), and the fourth casing portion (58).

6. 2. The casing of claim 1, further comprising a third casing portion (56) made of an electrically insulating material and disposed between the first casing portion (52) and the first connection lead (72), and a fourth casing portion (58) made of an electrically insulating material and disposed between the second casing portion (54) and the first connection lead (72), wherein the third casing portion (56) contacts a first side (80) of the first connection lead (72) and the fourth casing portion (58) contacts a second side (82) of the first connection lead (72) opposite the first side (80).

7. 2. The casing of claim 1, wherein said first casing portion (52) at least partially surrounds said second casing portion (54).

8. 2. A casing according to claim 1, wherein the first connecting surface (68) and the second connecting surface (70) are located on a common connecting plane (E).

9. 2. A casing as set forth in claim 1, wherein said first casing portion (52) is generally pot-shaped and said second casing portion (54) is ring-shaped.

10. 10. A sealed switching device comprising: a casing (100) according to any one of claims 1 to 9; and a temperature-dependent switch (10) configured to switch between a closed state and an open state in a temperature-dependent manner, wherein in the closed state the temperature-dependent switch (10) establishes a conductive connection between a first external terminal (48) and a second external terminal (50), and in the open state the temperature-dependent switch (10) interrupts the conductive connection, the temperature-dependent switch (10) being disposed in a receptacle (66) within the casing (100).

11. 11. The sealed switching device of claim 10, wherein the temperature-dependent switch (10) includes a temperature-dependent switching mechanism (14) and a switch housing (12) in which the temperature-dependent switching mechanism (14) is disposed, and the first external terminal (48) and the second external terminal (50) are disposed on the switch housing (12).

12. 12. The sealed switching device of claim 11, wherein the switch housing (12) comprises a lower portion (16) made of a conductive material and a cover portion (18) made of an electrically insulating material that closes the lower portion (16), and the first external terminal (48) and the second external terminal (50) are disposed on the cover portion (18).

13. 13. The sealed switching device of claim 12, wherein the casing further comprises a fourth casing portion made of an electrically insulating material, the fourth casing portion being annularly disposed around the switch housing and electrically insulating the first connecting lead from the lower portion.

14. 12. The sealed switching device of claim 11, wherein the switch housing (12) is connected to the second casing part (54) by welding or soldering.

15. 11. The sealed switching device of claim 10, wherein the casing (100) further comprises a fifth casing portion (92) made of metal, the fifth casing portion (92) closing the second casing portion (54) on at least one side and being fixed to the second casing portion (54) by welding or soldering.

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