Temperature-dependent switch

Abstract

To achieve a high functional reliability and a long service life with an inexpensive and simple configuration, in a temperature-dependent switch.SOLUTION: A temperature-dependent switch (10) includes a first external terminal (14), a second external terminal (16), and a temperature-dependent switching mechanism (12). The switching mechanism (12) includes a temperature-dependent switching element (28). The switching element switches the switching mechanism (12) between a closed position and an open position. The switching mechanism (12) establishes an electrically conductive connection between the first external terminal (14) and the second external terminal (16) in the closed position, and disconnects the electrically conductive connection in the open position. The switching mechanism (12) also includes a spring element (30) that is permanently electrically and mechanically connected in series to the switching element (28). In addition, the switching mechanism (12) includes a connecting component (32) that is arranged between the spring element (30) and the switching element (28) and is attached to the spring element (30) and the switching element (28).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a temperature dependent switch. [Background technology]

[0002] In principle, a large number of temperature-dependent switches are already known. An exemplary temperature-dependent switch is disclosed in DE 198 07 288 A1.

[0003] Such a temperature-dependent switch is used in a known manner to monitor the temperature of a device: for this purpose, for example, the switch is brought into thermal contact, or rather contacted, via one of its outer surfaces with the device to be protected, so that the temperature of the device to be protected influences the temperature of a switching mechanism arranged inside the switch.

[0004] The switch is electrically connected in series in the supply circuit of the device to be protected by an external electrical connection via a connecting line, so that below the response temperature of the switch, the supply current of the device to be protected flows through the switch.

[0005] A temperature-dependent switching mechanism installed in the switch ensures the temperature-dependent switching behavior of the switch. This temperature-dependent switching mechanism is usually arranged between two electrodes, each of which is electrically connected to one of the two external terminals. Below the response temperature of the switch or below the response temperature of the switching mechanism, this temperature-dependent switching mechanism is in a closed position and establishes a conductive connection between the two external electrodes of the switch, and above the response temperature of the switch, the temperature-dependent switching mechanism changes to an open position and the conductive connection between the two external electrodes of the switch is disconnected or interrupted.

[0006] The temperature-dependent switching mechanism thus ensures that in its closed position, which is below the response temperature of the switch, it closes the supply circuit of the device to be protected, and in its open position, which is above the response temperature of the switch, it interrupts the supply circuit of the device to be protected. With this type of temperature-dependent switch it is therefore ensured that in the event of unwanted overheating the electrical device is automatically de-energized by the switch and thus switched off.

[0007] Thus, such a temperature dependent switch provides protection against over-temperature in any kind of electrical device.

[0008] The temperature dependent switching element is configured such that its geometry changes as a function of temperature and is particularly responsible for the temperature dependent switching behavior of the switching mechanism of the switch. When the switch response temperature is reached and / or exceeded, the temperature dependent switching element changes its geometry to move the switching mechanism from its closed position to its open position. Typically, the temperature dependent switching element is a bimetallic or trimetallic element and is constructed as a multi-layer active sheet metal component consisting of two, three or more interconnected parts having different thermal expansion coefficients. The connection of the individual layers of metal or metal alloy in such bimetallic or trimetallic elements is usually made in a tightly bonded or positively locked manner, achieved for example by rolling.

[0009] This type of bimetallic or trimetallic switching element consists of a first stable geometric configuration (low temperature configuration) that is stable at a low temperature below the response temperature of the switch, which corresponds to the response temperature of the switching element, and a second stable geometric configuration (high temperature configuration) that is stable at a high temperature above the response temperature of the bimetallic or trimetallic switching element. Thus, the temperature dependent switching element switches from its low temperature configuration to its high temperature configuration as a function of temperature in a hysteretic manner.

[0010] When the temperature of the device to be protected increases such that the temperature of the temperature dependent switching element becomes higher than the response temperature of the switching element, the switching element changes state from its cold configuration to its hot configuration, thereby moving the switching mechanism from its closed position to its open position and interrupting the flow of current through the switch. When the temperature of the switch, and thus of the temperature-dependent switching element, falls below the so-called response temperature of the switching element as a result of cooling of the device to be protected, the switching element changes its geometric shape again from its hot configuration to its cold configuration, so that the switching mechanism is returned to its closed position and current can again flow through the switch.

[0011] Typically such temperature dependent switching elements made of bimetal or trimetal are constructed such that the above-mentioned response temperature of the switching element is lower than the response temperature of the switching element, but in principle a temperature dependent switching element can also be constructed such that its response temperature is within the same temperature range as the response temperature, or even exactly the same temperature.

[0012] In addition to the temperature-dependent switching element, an additional spring element is often used in the switching mechanism of such a temperature-dependent switch, which in the closed position generates or at least helps generate a mechanical closing pressure of the switching mechanism. The spring element is a temperature-independent spring element, preferably made of metal. This spring element releases the switching element in particular in the closed position of the switching mechanism, since the switching element has to exert less force or no force at all in order to generate a mechanical closing pressure in the closed position of the switching mechanism.

[0013] Temperature dependent switches, in which the switching mechanism has a temperature independent spring element in addition to a temperature dependent switching element, can be classified into two functionally distinct configurations with respect to the configuration, arrangement and type of interaction of the switching and spring elements.

[0014] According to a first configuration, the spring element is electrically and mechanically connected in parallel with a temperature-dependent switching element in the switch. A switch with such an arrangement of the switching mechanism is disclosed, for example, in DE-OS 197 48 589.

[0015] In this configuration of the switching mechanism, the spring element and the temperature-dependent switching element are typically disk-shaped and are connected to one another via a moving contact, the spring element being configured as a spring disk and being centrally attached to the moving contact. The temperature dependent switching element is usually configured as a bimetallic snap disk, which is arranged with a central opening on the moving contact, and in the closed position of the switching mechanism, the spring disk presses the moving contact against a stationary mating contact, which is arranged on or forms the first electrode of the switch, electrically connected to an external terminal of the switch, and at its outer edge on a second electrode of the switch, which is electrically connected to a second external terminal of the switch. Thus, in the closed position of the switching mechanism, a current flows between the two electrodes via the spring disk, which simultaneously generates a contact pressure, with which the moving contact is pressed against the stationary contact. The bimetallic snap disk can be attached without mechanical force in the closed position of the switching mechanism and is preferably not energized, which has a positive effect on the service life.

[0016] According to a second configuration, the spring element is not electrically and mechanically connected in parallel with the temperature-dependent switching element in the switching mechanism, but in series. Switches with such a switching mechanism configuration are disclosed, for example, in the initially mentioned German Patent Publication 198 07 288. A switch according to the invention is also a switch with such a switching mechanism connected in series.

[0017] In this switching mechanism configuration, the spring element is typically configured as an elongated spring tongue made of a metal and the temperature dependent switching element is configured as an elongated spring tongue made of a bimetal or trimetal. A first end of the spring element is attached to a first electrode electrically connected to a first external terminal of the switch. An opposite second end of the spring element is rigidly connected to a temperature dependent switching element. A free end of the temperature dependent switching element, the opposite end of the switching element attached to the spring element, includes a movable contact that interacts with a fixed contact disposed on a second electrode of the switch electrically connected to a second external terminal.

[0018] In this second configuration of the switching mechanism, the movable contact is pressed against the fixed contact by both the spring element and the temperature-dependent switching element in the closed position of the switching mechanism, which therefore jointly generate a closing pressure in the closed position of the switching mechanism due to their series connection and attachment to each other.

[0019] As mentioned, due to the configuration of the switching mechanism, the switching mechanism is not only mechanically but also electrically connected in series, so that in the closed position of the switching mechanism, current flows in series through the spring element and the temperature-dependent switching element. The switching element is more disadvantageous compared to the above-mentioned parallel configuration of the switching mechanism because the temperature dependent switching element is therefore permanently biased in the closed position of the switch and is therefore subject to greater stress.

[0020] However, this is also advantageous for certain applications, since the series-connected configuration of the switching mechanism means that the temperature-dependent switching element heats up very quickly at high operating currents, so that such a switch reacts not only to overtemperatures but also to overcurrents. Furthermore, the series-connected configuration of the spring element and the switching element is significantly more cost-effective and easier to realize than the parallel configuration, since the switching mechanism itself and the housing of the switching mechanism require significantly simpler and smaller components. The series configuration of the switching mechanism is therefore particularly suitable for the cost-effective use of temperature-dependent switches.

[0021] Moreover, in the case of a switching mechanism in the pure configuration of a spring and a switching element, the following further points should be noted: If the temperature-dependent switching element is made of a bimetal or trimetal, the switching element, like all bimetal or trimetal elements, undergoes a so-called creep phase during the transition from the closed position to the open position, in which the switching element gradually deforms as a result of the increase in temperature, but does not suddenly snap from its low-temperature configuration to its high-temperature configuration. This creep phase occurs not only when the temperature of the bimetal or trimetal element approaches its response temperature from below, but also when it approaches its response temperature from above. In both cases, this leads to significant structural changes. The creep behavior of bimetal or trimetal elements can also change, especially as a result of aging or long-term operation.

[0022] During the opening operation, creeping can reduce the force that the temperature-dependent switching element exerts on the fixed contact. During the closing operation, the contact gradually approaches the fixed contact during the closing phase, which can cause a risk of arcing. This creeping behavior of the switching element is compensated for in the switch known from DE 198 07 288 A1 by a spring element mechanically connected in series with the switching element. If the geometry of the switching element gradually changes during the creep phase, this is immediately compensated for by the spring element. The spring element therefore acts as a kind of compensation spring which compensates for this undesirable creep effect of the switching element.

[0023] Although the switch known from DE 198 07 288 A1 has proven advantageous at least for certain applications, e.g. protection against excess currents, and the phase problems of the creep phase mentioned above can be compensated for by spring elements, there is still room for improvement.

[0024] For example, it has been found that attaching a temperature dependent switching element to a spring element using the standard welding and soldering methods typically used for this often results in damage to both elements in practice. Since both the spring element and the temperature-dependent switching element are usually constructed as spring tongues made of very thin sheet metal, such soldered or welded joints have to be made very carefully and with high sensitivity, which is usually only possible by hand and can hardly be automated. Due to the fragile construction of both elements, the switching mechanism also often lacks mechanical stability, which leads to a relatively low robustness of the switching mechanism against vibrations. Summary of the Invention [Problem to be solved by the invention]

[0025] In this context, the object of the present invention is to overcome the above-mentioned drawbacks by creating a temperature-dependent switch with a switching mechanism according to the second configuration described above (series connection of a spring element and a switching element), in which high performance reliability and long life are achieved with a cheap and simple configuration. [Means for solving the problem]

[0026] According to the invention, this object is achieved by a temperature dependent switch as defined in claim 1. The temperature dependent switch according to the invention comprises a first external terminal, a second external terminal and a temperature dependent switching mechanism. The temperature dependent switching mechanism includes a temperature dependent switching element configured to change its geometric shape in response to its temperature, the switching element switching the switching mechanism between a closed position and an open position, where in the closed position the switching mechanism establishes a conductive connection between the first external terminal and the second external terminal, and in the open position the switching mechanism breaks the conductive connection. The temperature dependent switching mechanism also includes a spring element permanently electrically and mechanically connected in series with the temperature dependent switching element. The temperature dependent switching mechanism further includes a connecting piece disposed between the spring element and the temperature dependent switching element and attached to the spring element and the temperature dependent switching element.

[0027] In the switch according to the invention, the spring element and the temperature-dependent switching element are permanently electrically and mechanically connected in series in a manner similar to the switch known from DE 198 07 288 A1. However, according to the invention, an additional connecting part is further provided, which is arranged between the spring element and the temperature-dependent switching element and which is attached both to the temperature-dependent spring element and to the temperature-dependent switching element. This connecting part is preferably a dimensionally stable part, for example in the form of a metal sheet, which is attached on the one hand to the spring element and on the other hand to the temperature-dependent switching element.

[0028] Providing such an additional connection part between the spring element and the temperature-dependent switching element offers various advantages. Firstly, it simplifies the manufacture of the switching mechanism, since the spring element and the switching element do not have to be directly attached to each other, and in fact both elements are typically made of very thin and fragile sheet metal. The additional connection part therefore also increases the stability of the mechanical connection between the spring element and the temperature-dependent switching element. This increases the overall stability of the switching mechanism. Moreover, the electrical resistance of the switching mechanism can be individually adapted to the desired switching behavior by choosing a suitable material for the connection parts.

[0029] A further advantage of the connecting piece is that it provides additional height, so that the spring element and the temperature dependent switching element do not have to bend as much in the closed position of the switching mechanism to generate sufficient closing pressure. The connecting piece therefore provides mechanical relief for the spring element and the temperature dependent switching element in the closed position of the switching mechanism.

[0030] The connecting part can also be used as a carrier material that is integrally connected to a conveyor belt during automated manufacturing of the switch. For example, the connecting part can be a metal sheet that is integrally connected to an endless conveyor belt during automated manufacturing of the switching mechanism, and to which the spring element and the temperature-dependent switching element are then automatically attached. The metal sheet can then be stamped out of the conveyor belt, which makes it easy to pre-manufacture the parts of the switching mechanism, including the spring element, the connecting element and the switching element, which can then be stored as bulk material.

[0031] Without such additional connecting parts, it would not be possible to attach the switching element directly to the spring element in the automated manner described above, since both the spring element and the switching element are usually constructed as very thin metal sheets, which are not suitable as conveying materials for conveyor belts.

[0032] Thus, a further aspect of the invention relates to a method of manufacturing a temperature dependent switch, the method comprising the steps of: (i) providing a conveyor belt having a plurality of connecting pieces each comprising a metal sheet connected together; (ii) attaching the spring element and the temperature dependent switching element to one of a plurality of connecting pieces to electrically and mechanically connect the spring element in series with the temperature dependent switching element; (iii) separating one of the connection pieces from the conveyor belt to form a switching mechanism assembly including one of the connection pieces having a spring element and a temperature dependent switching element attached thereto; (iv) connecting the switching mechanism assembly to the first external terminal and the second external terminal to form a temperature dependent switch having a temperature dependent switching mechanism, the temperature dependent switching element configured to change its geometric shape in response to its temperature, switching the switching mechanism between a closed position and an open position, where in the closed position the switching mechanism establishes a conductive connection between the first external terminal and the second external terminal, and where in the open position the switching mechanism interrupts the conductive connection; (v) repeating steps (ii)-(iv) for a greater number of connection parts.

[0033] In summary, the switch according to the invention is relatively simple to manufacture and has a switch mechanism which is mechanically more stable than the switch disclosed in DE 198 07 288 A1.

[0034] Thus, the above objective is fully achieved.

[0035] According to one embodiment, the connection piece is essentially plate-shaped.

[0036] The connecting piece preferably comprises a metal sheet which is flat against one spring element and flat against the other spring element, which allows a simple and mechanically stable connection between the spring element, the connecting piece and the switching element, while at the same time ensuring good electrical contact between these three parts.

[0037] According to yet another embodiment, a first side of the connection piece is attached to the spring element by a first firmly bonded connection and a second side of the connection piece is attached to the temperature dependent switching element by a second firmly bonded connection.

[0038] Preferably, the two mentioned sides are on opposite sides of the connection piece. It is particularly preferred that the spring element is attached to the upper side of the connection piece and the switching element to the lower side of the connection piece. Both firmly bonded connections are made in the same way. For example, the firmly bonded connections between the spring element and the connecting piece on the one hand and the connecting piece and the switching element on the other hand can be soldered or welded connections, respectively.

[0039] According to yet another embodiment, the connection piece is thicker than the spring element and the temperature dependent switching element.

[0040] In other words, the connecting part is preferably thicker than the spring element and the temperature-dependent switching element, thus providing additional mechanical reinforcement and increasing the stability of the switching mechanism. Due to its greater material thickness, it is better suited as a carrier material that is integrally connected to a conveyor belt in the case of automated production of such switching mechanisms.

[0041] The spring element and the connecting part are preferably each made of a metal, particularly preferably a metal sheet. The connecting part can be made of a metal different from that of the spring element. The temperature-dependent switching element is preferably made of a bimetal or trimetal.

[0042] According to yet another embodiment, the spring element and the temperature-dependent switching element are only indirectly connected via a connecting piece, but not directly, which has a positive effect on the freedom of movement of the spring element and the temperature-dependent switching element.

[0043] According to yet another embodiment, a first end of the spring element is attached to a first electrode of the switch, the first electrode being electrically connected to the first external terminal, and a second end of the spring element is attached to the connecting piece.

[0044] This measure results in a simple construction in which the spring element is preferably configured as an elongated spring tongue which is attached at its first end in the manner of a cantilever to the first electrode and thus firmly clamped, and attached at its free second end to the connecting part.

[0045] According to yet another embodiment, a first end of the temperature-dependent switching element is attached to the connection part and a second end of the temperature-dependent switching element carries a movable contact which is pressed by a spring element and the temperature-dependent switching element against a fixed contact in a closed position of the switching mechanism, said fixed contact being arranged on a second electrode electrically connected to a second external terminal, said temperature-dependent switching element being configured to change its geometric shape depending on its temperature so as to lift the movable contact away from the fixed contact in an open position of the switching mechanism to interrupt the conductive connection.

[0046] Thus, the spring element and the temperature dependent switching element together generate a contact pressure in the closed position of the switching mechanism, which presses the movable contact against the fixed contact, and at the same time the spring element acts as a kind of compensation spring, compensating for undesired creeping movements of the temperature dependent switching element.

[0047] According to yet another embodiment, the first end of the spring element and the second end of the temperature-dependent switching element are located on the same side of the connecting piece relative to the connecting piece.

[0048] This results in the spring element, the connection part and the switching element being arranged in a sort of V- or U-shape, which makes it possible to realize a switching mechanism with a low height.

[0049] According to yet another embodiment, the first electrode and the second electrode are held at a distance from each other by an insulating material carrier, wherein the temperature dependent switching mechanism is disposed in a recess in the insulating material carrier between the first electrode and the second electrode.

[0050] On the one hand, the insulating material carrier therefore electrically insulates the two electrodes from each other and also serves as a mechanical structural part supporting both electrodes and, on the other hand, increases the stability of the switch structure. The insulating material carrier can also serve as or form part of the housing.

[0051] According to yet another embodiment, the first external terminal and the second external terminal are arranged parallel to each other in a common plane.

[0052] This greatly simplifies the electrical connections of the switch.

[0053] According to yet another embodiment, the first electrode is in the form of a cover or plate or disk and is surrounded along its entire periphery by an insulating material carrier.

[0054] The first electrode thus acts as a cover for the switch and may be preferably hot stamped with an insulating material carrier and sealed all around its periphery, thereby improving the mechanical sealing of the switch.

[0055] According to yet another embodiment, the wire connection element is at least partially encapsulated or embedded within the insulating material.

[0056] For example, the wire connection elements can be embedded in an insulating material carrier, i.e., shielded and electrically isolated from the switching mechanism, while at the same time being housed within the switch to save space.

[0057] It is understood that the features mentioned above and those to be described below can be used not only in the combinations indicated in each case, but also in other combinations or even by themselves, without departing from the scope of the invention. [Brief description of the drawings]

[0058] An example of an embodiment of the invention is illustrated in the drawings and explained in more detail in the following description. [Figure 1] 1 shows a schematic cross-sectional view of an exemplary embodiment of a switch according to the invention, with the temperature dependent switching mechanism in its closed position. [Diagram 2] 2 shows a schematic cross-sectional view of an exemplary embodiment of the switch according to the invention shown in FIG. 1, with the switching mechanism in an open position; [Diagram 3] 2 shows a schematic top view of an exemplary embodiment of the switch according to the invention shown in FIG. 1; [Figure 4] FIG. 2 is a schematic diagram showing a part of the inventive method for automatically manufacturing a switch. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] 1 and 2 each show a schematic cross-sectional view of one embodiment of a temperature dependent switch according to the present invention, generally labelled 10.

[0060] Figure 1 shows the switch 10 in a closed position, and Figure 2 shows the switch 10 in an open position.

[0061] The switch 10 comprises a temperature dependent switching mechanism 12 which is configured to switch the switch 10 from its closed position to its open position and vice versa depending on its temperature.

[0062] In the closed position of the switch 10, shown in Figure 1, the switching mechanism 12 establishes a conductive connection between the two external terminals 14, 16 of the switch. In contrast, in the open position of the switch 10, shown in Figure 2, the switching mechanism 12 breaks the electrically conductive connection between the first external terminal 14 and the second external terminal 16.

[0063] The first external terminal 14 is conductively connected to a first electrode 18, which also forms a cover of the switch 10. The second external terminal 16 is electrically conductively and preferably integrally connected to a second electrode 20, which is arranged parallel to and spaced apart from the first electrode 18. Both electrodes 18, 20 are preferably configured as flat electrodes. The switching mechanism 12 is located inside the switch 10 in the space between the two electrodes 18, 20.

[0064] The two electrodes 18, 20 are held by an insulating material carrier 22, which is essentially pot-shaped and forms the lower housing part of the switch 10. The insulating material carrier 22 is formed around the second electrode 20 by overmolding or casting in such a way that the second electrode 20 is an integral part of the lower housing part. The lower part of the housing is closed by the first electrode 18, which acts as a cover part. The first electrode 18 is surrounded along its entire periphery by the insulating material carrier 22 and is held in restraint by a hot-stamped upper edge 24 of the insulating material carrier 22.

[0065] 3, the two external terminals 14, 16 are led out parallel to each other from an insulating material carrier 22. A wire connection element 26 arranged inside the insulating material carrier 22 extends transversely, preferably perpendicularly, to the two electrodes 18, 20.

[0066] The wire connection element 26 connects the first electrode 18 to the first external terminal 14 . In this way, the two external terminals 14, 16 can be arranged in a common plane, even though the two electrodes 18, 20 are arranged vertically offset. By arranged in a common plane, it is meant that the two external terminals 14, 16 are configured as a planar or plate-like connection, with their respective upper sides arranged in a first common plane and their respective lower sides arranged in a common second plane extending parallel to the first common plane. By arranging the two external terminals in a common plane in this way, the electrical connection of the switch 10 is made many times simpler.

[0067] The wire connection elements 26 are preferably completely contained within an insulating material to shield and electrically insulate the wire connection elements 26 from the switching mechanism 12. In the exemplary embodiment shown, the wire connection elements 26 are integrated into the insulating material carrier 22 and are therefore spatially separated from the switching mechanism 12.

[0068] The switching mechanism 12 comprises a temperature-dependent switching element 28, a spring element 30 and a connecting part 32. In this case, the temperature-dependent switching element 28 is a bimetallic element having an elongated spring tongue shape. The spring element 30 is made of metal and configured as an elongated spring tongue. The connecting part 32 is configured as a plate-shaped metal sheet, the material thickness of which is greater than the material thickness of the switching element 28 and preferably greater than the material thickness of the spring element 30.

[0069] The spring element 30, the connecting piece 32 and the switching element 28 configured as a bimetal element are electrically and mechanically connected in series. The spring element 30 and the switching element 28 are only indirectly connected via the connecting piece, but not directly. The connecting piece 32 is arranged as an intermediate layer between the spring element 30 and the switching element 28 and is attached separately to the spring element 30 and to the switching element 28.

[0070] A first end 34 of the spring element 30 is attached in a firmly adhesive manner to the first electrode 18. Starting from this first end 34, the spring element 30 projects in a cantilever manner into a cavity formed inside the switch 10. An opposite second free end 36 of the spring element 30 is attached in a firmly bonded manner (for example by soldering or welding) to a first side 38 of the connecting piece 32. A second side 40 of the connecting piece 32, opposite the first side 38, is attached in a firmly adhesive manner (for example by soldering or welding) to a first end 42 of the switching element 28.

[0071] At a second end 44 opposite the first end 42 , the switching element 28 carries a movable contact 46 which cooperates with a fixed contact 48 disposed on the second electrode 20 .

[0072] In the closed position of the switching mechanism 12, the spring element 30 and the switching element 28 urge the movable contact 46 against the fixed contact 48, thereby closing the switch 10 and establishing a conductive connection between the two external terminals 14, 16. When the temperature of the switching element 28 increases, either as a result of increased current flow through the switch 10 or as a result of an increase in the outside air temperature, a creep phase of the switching element 28 begins, in which the spring force of the switching element 28 acting against the force of the spring element 30 decreases, so that the connecting piece 32 moves downward relative to the position shown in FIG. 1. However, the mechanical series connection of the spring element 30, the mechanical connecting piece 32 and the switching element 28 continues to press the movable contact 46 against the fixed contact 48. If the temperature of the switching element 28 then increases further up to or exceeds the response temperature of the switching element 28, the switching element 28 snaps over to the high temperature configuration shown in FIG. 2. Now, the switching mechanism 12 is brought to its open position and the conductive connection between the two external terminals 14, 16 is interrupted.

[0073] Furthermore, at least one recess 49 is provided in the insulating material carrier 22, through which the second electrode 20 is accessible from the outside. On the one hand, this improves the thermal connection of the switch 10 and, on the other hand, allows an automated functional test of the switch 10.

[0074] 4 shows a schematic top view of a portion of an assembled belt to illustrate a method of automated manufacturing of temperature dependent switch 10. In particular, a conveyor belt 50 is shown, which in the illustrated case includes a number of holes 52 that serve to drive conveyor belt 50 in the direction of arrow 54. However, depending on the type of conveyor belt drive, these holes 52 may be eliminated or may be replaced with other types of engagement elements that can be engaged by the conveyor belt drive.

[0075] The conveyor belt 50 is made of sheet metal and is integrally connected to a number of prefabricated connecting pieces 32, only one of which is shown in FIG. 4. The connecting piece 32 is thus part of the conveyor belt 50 and serves as a carrier material for mounting other components of the switching mechanism 12 of the switch 10 during the manufacturing of the switching mechanism 12.

[0076] In a first step, a spring element 30 and a temperature-dependent switching element are mounted on each of a number of connecting pieces 32, such that the spring element 30 is electrically and mechanically connected in series with the temperature-dependent switching element 28. As already mentioned, the spring element 30 is attached to a first side 38 of the connecting piece 32 by a first firmly adhesive connection. The temperature-dependent switching element 28 is attached to an opposite second side 40 of the connecting piece 32 by a second firmly adhesive connection. Preferably, the movable contact 48 is already previously attached to the switching element 28.

[0077] As soon as the switching mechanism assembly, comprising the switching elements 28, the spring elements 30 and the connecting pieces 32, is fully assembled, the switching mechanism assembly can be separated from the conveyor belt 50 by separating the connecting pieces 32 along the dashed separation line 56. In this way, the switching mechanism assembly can be produced in an automated manner, for example as a semi-finished product that can be stored as bulk material.

[0078] The switching mechanism assembly thus manufactured can be connected to the first and second external terminals 14, 16 to form the temperature dependent switching mechanism 12 and can be inserted as a whole or individually into an insulating material carrier 22 as shown in Figures 1 and 2.

[0079] It will be appreciated that if the switch is manufactured automatically, the above steps are repeated for each additional connection piece 32 connected to the conveyor belt 50 to manufacture additional switches 10.

Claims

1. A temperature dependent switch (10) having a first external terminal (14), a second external terminal (16), and a temperature dependent switching mechanism (12), the temperature dependent switching mechanism (12) comprises a temperature dependent switching element (28) configured to change its geometric shape in response to its temperature, the switching element (28) switching the switching mechanism (12) between a closed position and an open position, in which the switching mechanism (12) establishes a conductive connection between the first external terminal (14) and the second external terminal (16) and in which the switching element (28) breaks the conductive connection; The temperature dependent switching mechanism (12) includes a spring element (30) permanently electrically and mechanically connected in series with a temperature dependent switching element (28); The temperature dependent switch (10) is further characterized in that the temperature dependent switching mechanism (12) further comprises a connecting piece (32) disposed between the spring element (30) and the temperature dependent switching element (28) and attached to the spring element (30) and the temperature dependent switching element (28).

2. 2. The temperature dependent switch of claim 1, wherein the connecting piece (32) is essentially plate-like.

3. 2. The temperature dependent switch of claim 1, wherein a first side (38) of the connecting piece (32) is attached to the spring element (30) by a first firmly adhesive connection and a second side (38) of the connecting piece (32) is attached to the temperature dependent switching element (28) by a second firmly adhesive connection.

4. 2. The temperature dependent switch of claim 1, wherein the connecting piece (32) is thicker than the spring element (30) and the temperature dependent switching element (28).

5. 2. The temperature dependent switch of claim 1, wherein said spring element (30) and said connecting piece (32) are each made of metal.

6. The temperature dependent switch of claim 1 , wherein the temperature dependent switching element (28) comprises a bimetal or a trimetal.

7. 2. The temperature dependent switch of claim 1, wherein the spring element (30) and the temperature dependent switching element (28) are not directly connected to each other but only indirectly via a connecting piece (32).

8. 2. The temperature dependent switch of claim 1, wherein a first end (34) of the spring element (30) is attached to a first electrode (18) electrically connected to the first external terminal (14), and a second end (36) of the spring element (30) is attached to the connecting part (32).

9. A first end (42) of the temperature dependent switching element (28) is attached to the connecting piece (32) and a second end (44) of the temperature dependent switching element (28) carries a movable contact (46) which, in the closed position of the switching mechanism (12), 2. The temperature dependent switch of claim 1, wherein the movable contact is pressed against the fixed contact by a spring element and a temperature dependent switching element, the fixed contact being disposed on a second electrode that is electrically connected to a second external terminal, the temperature dependent switching element being configured to change its geometric shape in response to its temperature to lift the movable contact away from the fixed contact in an open position of the switching mechanism to interrupt the conductive connection.

10. 10. The temperature dependent switch of claim 8 or 9, wherein the first end (34) of the spring element (30) and the second end (44) of the temperature dependent switching element (28) are on the same side of the connecting element (32) relative to the connecting element (32).

11. 10. The temperature dependent switch of claim 8 or 9, wherein the first electrode (18) and the second electrode (20) are held at a distance from each other by an insulating material carrier (22), and the temperature dependent switching mechanism (12) is disposed in a recess in the insulating material carrier (22) between the first electrode and the second electrode (18, 20).

12. 10. The temperature dependent switch according to claim 8 or 9, wherein the first external terminal (14) and the second external terminal (16) are arranged parallel to each other in a common plane, and the first external terminal (14) is electrically connected to the first electrode (18) via a wire connection element (26), the wire connection element (26) being aligned transversely to the first and second electrodes (18, 20).

13. 9. The temperature-dependent switch according to claim 8, wherein the first electrode (18) is made in the form of a cover or plate or disk and is surrounded along its entire periphery by an insulating material carrier (22).

14. 13. The temperature dependent switch of claim 12, wherein the wire connection element (26) is at least partially encased by or embedded in an insulating material.

15. A method for manufacturing the temperature dependent switch (10) of claim 1, comprising the steps of: (i) providing a conveyor belt (50) having a plurality of connecting pieces (32) made of sheet metal connected together; (ii) attaching the spring element (30) and the temperature dependent switching element (28) to one of a plurality of connecting pieces (32) to electrically and mechanically connect the spring element (30) in series with the temperature dependent switching element (28); (iii) separating one of the connection pieces (32) from the conveyor belt (50) to form a switching mechanism assembly including the one of the connection pieces (32) having the spring element (30) and the temperature dependent switching element (28) attached thereto; (iv) connecting the switching mechanism assembly to the first external terminal (14) and the second external terminal (16) to form a temperature dependent switch (10) having a temperature dependent switching mechanism (12), the temperature dependent switching element (28) configured to change its geometric shape in response to its temperature to switch the switching mechanism (12) between a closed position and an open position, where in the closed position the switching mechanism (12) establishes a conductive connection between the first external terminal (14) and the second external terminal (16) and where in the open position the switching mechanism (12) breaks the conductive connection; (v) repeating steps (ii)-(iv) for a greater number of connection pieces (32).

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