METHOD FOR MOUNTING A TEMPERATURE-DEPENDENT SWITCH

Description

[0001] The present invention relates to a method for mounting a temperature-dependent switch.

[0002] Temperature-dependent switches are already known in many forms. An example of a temperature-dependent switch is disclosed in DE 10 2019 110 448 A1.

[0003] Such temperature-dependent switches serve, in a manner known per se, to monitor the temperature of a device. For this purpose, the switch is brought into thermal contact with the device to be protected, for example via one of its outer surfaces, so that the temperature of the device to be protected influences the temperature of the 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 connecting leads, so that below the switch's response temperature, the supply current of the device to be protected flows through the switch.

[0005] Such temperature-dependent switches comprise a temperature-dependent switching mechanism located within the switch housing. This mechanism opens or closes an electrically conductive connection between two electrodes of the switch depending on its temperature. More precisely, the temperature-dependent switching mechanism is configured to switch between a closed position, which the mechanism assumes below a response temperature and in which it establishes the electrically conductive connection between the two electrodes, and an open position, which the mechanism assumes above the response temperature and in which it breaks the electrically conductive connection.

[0006] The term "electrode" is to be interpreted in its most general sense in this context. It refers to an electrical contact point that serves to connect the switch to the electrical device to be protected, or that is in electrically conductive contact with such an external terminal of the switch. The electrodes can be inserted into the interior of the switch housing from the outside, attached to the switch housing, or formed by parts of the switch housing itself.

[0007] To enable the aforementioned temperature-dependent switching function, the temperature-dependent switching mechanism located inside the switch housing typically includes a bimetallic element. Upon reaching the response temperature, this element abruptly deforms from its low-temperature position to its high-temperature position, thereby lifting a movable contact element—mounted on a component that moves relative to the switch housing—from a stationary contact. The stationary contact is connected to one of the two electrodes, while the movable contact element interacts either via the bimetallic element or a spring element associated with the bimetallic element.

[0008] Designs are also known in which the movable component of the temperature-dependent switching mechanism is configured as a contact bridge, which is supported by the bimetallic part and directly establishes an electrical connection between the two electrodes. A temperature-dependent switch with such a switching mechanism is known, for example, from DE 197 08 436 A1.

[0009] In the two previously mentioned design variants, the bimetallic component is preferably designed as a bimetallic disc, which, in the low-temperature position, is preferably held in the switching mechanism without any force. The spring component, which is preferably designed as a spring-loaded snap disc, is mechanically coupled to the bimetallic component. The spring component is clamped in the switch housing, bonded to it by a material connection, or inserted or placed into the switch housing.

[0010] However, it is also possible to dispense with the spring element entirely, which is particularly the case in more cost-effective versions of such temperature-dependent switches. In such a case, the function of the spring element is taken over by the bimetallic element. An example of a temperature-dependent switch of this type is disclosed in DE 20 2009 012 616 U1.

[0011] Regardless of the specific design of the temperature-dependent switching mechanism, such switches are typically electrically connected to the device being protected via electrical leads or connectors attached to the two electrodes. Generally, flexible leads, rigid tabs, or a connecting cable are bonded directly to the electrodes for this purpose. In switches known from the prior art, the leads, tabs, or cables are often soldered or welded in place.

[0012] However, soldering or welding the supply lines or connection parts has proven problematic in many respects.

[0013] The commonly used soldering methods are difficult to automate and, moreover, are not environmentally friendly, particularly due to the lead-based solder and flux used. Furthermore, they can lead to cold solder joints, which should understandably be avoided at all costs.

[0014] An improved, material-bonded connection of the supply lines or connection parts could therefore, in principle, be achieved through welding; however, this also has several disadvantages. In particular, common welding processes are environmentally damaging and also time-consuming and expensive. Furthermore, such welding processes lead to significant heating of the switch, which can cause the welding process to trigger a switching operation of the temperature-dependent switching mechanism, a generally undesirable outcome.

[0015] Tests conducted by the applicant, in which connecting tabs or wires were soldered or welded to the switch housing, have shown that the resulting heat generation can also cause the stationary contact inside the switch housing, with which the temperature-dependent switching mechanism interacts, to detach from its associated electrode.

[0016] Similarly, due to heat generation, the stationary contact and the moving contact part of the temperature-dependent switching mechanism may unintentionally fuse together or at least be altered in their geometry to such an extent that the pre-assembled switches no longer switch or at least no longer switch reliably.

[0017] Furthermore, the heat generation can damage the bimetallic part and / or the spring part, undesirably altering the required switching characteristics of the derailleur.

[0018] In the worst case, all of this can lead to a total failure of the switch.

[0019] The heat generated inside the switch housing is particularly pronounced when the housing is made of metal and the leads or connections are welded or soldered directly to it. Due to the excellent thermal conductivity of metal, this results in a particularly high heat buildup inside the housing. This is all the more critical because the leads or connections are usually attached to the housing only after the switching mechanism has already been mounted inside or the housing has been closed – that is, after the switch itself is already a semi-finished component. Whether the heat generated inside the switch leads to any of the aforementioned damage can then only be monitored to a limited extent, or at least with considerable effort.

[0020] To prevent this, the leads and connecting parts are often bonded to the switch housing beforehand, i.e., before installing the temperature-dependent switching mechanism. However, this also has several disadvantages. Firstly, it makes handling the switch during installation more difficult, as the leads and connecting parts are "in the way" when installing the switching mechanism into the switch housing. Furthermore, to achieve a sealed switch housing, it is simpler to first insert the switching mechanism into the housing, close the housing, and only then attach the leads and connecting parts.

[0021] To enable the attachment of supply lines and connection components to the switch housing after the installation of the temperature-dependent switching mechanism, while still avoiding the aforementioned problem of unwanted heat generation within the switch housing, the aforementioned DE 10 2019 110 448 A1 proposes attaching the supply lines and connection components to the switch housing using ultrasonic welding. Compared to conventional welding methods, ultrasonic welding generates significantly less heat. It has been shown that this prevents most of the aforementioned problems. However, the use of ultrasonic welding is relatively expensive, as it requires highly specialized welding tools.

[0022] It is therefore an object of the present invention to provide an improved method for mounting a temperature-dependent switch that overcomes the problems mentioned above. In particular, the method should enable a secure and durable attachment of the external connections to the switch without damaging the temperature-dependent switching mechanism located inside the switch.

[0023] This problem is solved according to the invention by a method for manufacturing / assembling a temperature-dependent switch, which comprises the following steps: (i) Providing a switch housing with a first and a second electrode and a temperature-dependent switching mechanism arranged in the switch housing, the switching mechanism being configured to switch, depending on the temperature, between a closed position, which the switching mechanism assumes below a response temperature and in which the switching mechanism establishes an electrically conductive connection between the first and the second electrode, and an open position, which the switching mechanism assumes above the response temperature and in which the switching mechanism breaks the electrically conductive connection; (ii) Heating the switching mechanism to a temperature above the response temperature in order to bring the switching mechanism into the open position;and (iii) attaching a first external connection to the first electrode or to a part electrically connected to the first electrode by metallurgical joining under heat input while the switching mechanism is in the open position.

[0024] Thus, in the method according to the invention, it is also proposed to first install the switching mechanism in the switch housing and only then to attach the first external connection to the switch, which is prefabricated as a semi-finished product, by means of material-bonded joining under heat input (e.g. by soldering or welding).

[0025] However, the applicant has recognized that the aforementioned harmful effects, which can result from the heat generated for the switching mechanism located inside the switch housing, can surprisingly be reduced or even completely avoided by additionally heating the switching mechanism before the first external connection is attached, in order to bring it to a temperature above the response temperature of the switching mechanism.

[0026] This preheating of the switching mechanism ensures that it is intentionally moved into its open position. This not only interrupts the electrically conductive connection between the two electrodes, but also the thermal connection between them created by the switching mechanism. The heat generated during the initial external connection through the bonding process no longer has a detrimental effect on the components of the temperature-dependent switching mechanism, as it is already open and its components are not pressed together, unlike in the closed position.

[0027] The movable contact element typically provided on the switching mechanism is accordingly lifted off the stationary contact element, against which the movable contact element rests in the closed position of the switching mechanism, even before the first external connection is made. Direct heat conduction between the stationary and movable contact elements is thus prevented. Consequently, it is also prevented that the movable contact element of the switching mechanism is fused or welded to the stationary contact element or the first electrode due to the heat generated when the first external connection is attached to the first electrode.

[0028] Furthermore, the fragile components of the switching mechanism (e.g., the bimetallic part and the spring part) are typically located further away from the joining point of the first external connection or from the first electrode when the switching mechanism is in the open position than when it is in the closed position. Thus, the fragile components of the switching mechanism are effectively protected from the heat generated during the joining process by the preheating of the switching mechanism according to the invention, during which it is brought into the open position.

[0029] Furthermore, the method according to the invention has the advantage that an undesired switching operation of the switching mechanism, which can be caused by heat generation when attaching the first external connection, is also effectively prevented, since the switching mechanism is already in its open position at this time and remains in this open position due to the additional heat input during the attachment of the first external connection.

[0030] The above-mentioned task has therefore been completely solved.

[0031] According to one embodiment, the attachment of the first external connection by material-joining under heat input involves a soldering process or a welding process.

[0032] Since the switching mechanism is already in its open position during this process, and the resulting heat input into the interior of the switch housing, as mentioned above, therefore no longer has any detrimental effects on the switching mechanism, conventional soldering and welding processes can be used at low cost according to the invention. These material-bonded joining processes can be automated, resulting in a further cost advantage.

[0033] According to a further embodiment, the switching mechanism is heated to a temperature above the response temperature by heating the switch housing and the switching mechanism arranged therein by an external heat source.

[0034] The switching mechanism located inside the switchgear is therefore indirectly heated from the outside. This external heating results in a regular switching operation of the switchgear, thus preventing any damage to the switchgear itself. Heating via an external heat source is cost-effective and can be automated with comparatively low energy consumption.

[0035] Preferably, the temperature to which the switching device is heated in process step (ii) is greater than 100 °C. Particularly preferably, the switching device is heated to a temperature greater than 150 °C in process step (ii).

[0036] This ensures that the temperature-dependent switching mechanism is unambiguously brought into its open position before the procedure step (iii) is carried out.

[0037] According to a further embodiment, it is preferred that the switching mechanism is heated to a temperature above the response temperature by automatically passing the switch housing and the switching mechanism arranged therein through a heating section.

[0038] Such a heating section can, for example, be designed as a heating tunnel through which the switch housing is automatically traversed. This ensures continuous and therefore harmless heating of the switch housing. Such a heating section can also be easily integrated into an automated production or assembly line.

[0039] The installation of the first external connection by material-bonding joining under heat input is preferably carried out automatically after passing through the heating section.

[0040] According to a further embodiment, the method according to the invention comprises the following further step: (iv) attaching a second external connection to the second electrode or to a part electrically connected to the second electrode by joining it by material bonding under heat input.

[0041] This additional step (iv) can be performed before step (ii), i.e., before the switching mechanism is brought into its open position by external heating. This is particularly possible if the heat generated during the metallurgical joining of the second external connection does not have an excessively detrimental effect on the switching mechanism located inside the switch housing. This is especially true if the second external connection is located at a point on the switch that is further away from the switching mechanism and / or is not in direct thermal contact with it.

[0042] This type of design is particularly advantageous for switches where the two electrodes are located on opposite sides of the switch housing. In this case, the fragile components of the switching mechanism are often further away from the second electrode in the closed position than in the open position, while they are further away from the first electrode in the open position than in the closed position.

[0043] Therefore, if the second external connection is attached to the second electrode or a component connected to the second electrode while the switching mechanism is in the closed position, and the first external connection is attached to the first electrode or a component connected to the first electrode after the switching mechanism has been moved to its open position, then the fragile components of the switching mechanism are as far away as possible from the respective joining point during both joining processes. The heat generated during the two joining processes thus has as little impact as possible on the fragile components of the switching mechanism.

[0044] Depending on the design of the switch or the design of the switching mechanism contained therein, it may also be advantageous for both joining processes, i.e. the attachment of both external connections, to take place only after process step (ii), i.e. at a time when the switching mechanism is already in its open position.

[0045] According to a further embodiment, the switch housing has a lower part and a cover part closing the lower part and electrically insulated from the lower part, wherein the cover part is at least partly made of electrically conductive material, and wherein the first electrode is arranged on the cover part.

[0046] In this embodiment, the cover part of the switch housing is preferably made of metal. Accordingly, the heat generated during the joining process in process step (iii) is particularly high, so that the method according to the invention is particularly advantageous.

[0047] The lower part can also be made of electrically conductive material, such as metal. The contact points for the switch's external terminals can be either the outer surface of the cover facing away from the inside of the switch housing or the outer surface of the lower part facing away from the inside of the switch housing. Thus, the cover and lower part can themselves form the switch's terminal electrodes.

[0048] The first electrode can have a contact part that extends from the inside of the switch housing through the cover part to the outside. This contact part can therefore be a type of through-hole or through-hole contact that forms the first electrode on the inside and has a contact surface for the first external connection on the outside. In such a case, the heat conduction that occurs during joining in process step (iii) between the joining point and the first electrode is particularly high, so that in this case it is especially advantageous if the switching mechanism has already been brought into its open position according to the invention.

[0049] According to a further embodiment, the process with steps (i)-(iii) is repeated for a plurality of temperature-dependent switches, wherein the switch housings of the plurality of temperature-dependent switches are attached to a common conveyor belt during the execution of steps (i)-(iii).

[0050] This enables automated assembly of the switch.

[0051] Preferably, the conveyor belt has a plurality of receptacles to which one of the switch housings of the plurality of temperature-dependent switches is attached, wherein each of the plurality of receptacles has a connecting piece which is electrically conductively connected to the second electrode of the respective switch housing and to which the second external connection is attached by material joining under heat input.

[0052] This connector allows for a very simple method of attaching the second external connection. The receptacles provided on the conveyor belt, which are preferably ring-shaped, therefore serve not only to transport the switches, but also to simplify the assembly process for attaching the second external connection to the individual switches.

[0053] According to a further embodiment, the temperature-dependent switching mechanism includes a bimetallic component.

[0054] Within the scope of the present invention, a bimetallic part is understood to be a multilayered, active, sheet-like component consisting of two, three, or four inseparably bonded components with different coefficients of thermal expansion. The bonding of the individual layers of metals or metal alloys is either material-bonded or form-fit and is achieved, for example, by rolling.

[0055] Such bimetallic components exhibit a first geometric conformation in their low-temperature state and a second in their high-temperature state, switching between these conformations depending on the temperature, similar to hysteresis. When the temperature changes above the response temperature or below its return temperature, these bimetallic components snap into the other conformation.

[0056] According to a further embodiment, the temperature-dependent switching mechanism includes a spring part that interacts with the bimetallic part.

[0057] The bimetallic component is preferably a temperature-dependent bimetallic snap disc. The spring component is preferably a temperature-independent spring snap disc.

[0058] Further features and advantages of the present invention will become apparent from the accompanying drawings and their subsequent description.

[0059] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.

[0060] An embodiment of the invention is illustrated in the accompanying drawings and is explained in more detail in the following description. The drawings show: Fig. 1 a schematic sectional view of an exemplary temperature-dependent switch that can be mounted using the method according to the invention, wherein the switch is in its low-temperature position; Fig. 2 a schematic sectional view of the in Fig. 1 the switch shown, wherein the switch is in its high-temperature position; Fig. 3 a transport or assembly belt with several temperature-dependent switches for a schematic illustration of the method according to the invention in an exemplary embodiment; Fig. 4 a schematic top view of the in Fig. 3 The conveyor belt shown does not include the temperature-dependent switches; and Fig. 5 is a simplified flowchart to illustrate the process steps of the method according to the invention.

[0061] Fig. 1 and 2 Figure 1 shows an exemplary temperature-dependent switch that can be mounted using the method according to the invention. The switch as a whole is designated by the reference numeral 10.

[0062] Fig. 1 indicates the low temperature setting of switch 10. Fig. 2 indicates the high temperature setting of switch 10.

[0063] It goes without saying that the in Fig. 1 and 2 The switch 10 shown is only one example of various possible temperature-dependent switches that can be assembled using the method according to the invention. However, the manufacturing and assembly method according to the invention can also be used in principle for various other temperature-dependent switches that have a different design than the one shown. Fig. 1 and 2 Switch 10 shown. The one in Fig. 1 and 2 The switch 10 shown is below described as an example of a possible temperature-dependent switch in order to explain the basic structure and function of such a temperature-dependent switch.

[0064] The switch 10 has a switch housing 12, inside of which a temperature-dependent switching mechanism 14 is arranged. The switch housing 12 comprises a pot-shaped lower part 16 and a cover part 18, which is held to the lower part 16 by a bent or crimped upper edge 20 of the lower part 16.

[0065] Both the lower part 16 and the lid part 18 are in the Fig. 1 and 2 The example shown for switch 10 is made of an electrically conductive material, preferably metal. An insulating film 22 is arranged between the lower part 16 and the cover part 18. The insulating film 22 provides electrical insulation between the lower part 16 and the cover part 18. The insulating film 22 also provides a mechanical seal, preventing liquids or contaminants from entering the interior of the switch housing 12.

[0066] Since the lower part 16 and the cover part 18 in this example are each made of electrically conductive material, thermal contact can be established with an electrical device to be protected via their outer surfaces. The outer surfaces also serve as the external electrical connection for the switch 10. For example, a first external electrical connection can be made to the switch 10 on the outer surface 24 of the cover part 18, and a second external electrical connection can be made on the outer surface 26 of the lower part 16.

[0067] On the outside of the lid part 18, there is the one in Fig. 1 and 2 In the example shown of switch 10, a further insulating layer 28 is arranged.

[0068] The switching mechanism 14 is clamped between the lower part 16 and the cover part 18. The switching mechanism 14 comprises a bimetallic part 30, a spring part 32, and a movable contact part 34.

[0069] The bimetallic part 30 comprises a temperature-dependent bimetallic snap disc with a central opening provided therein, by which the bimetallic snap disc is placed over the movable contact part 34.

[0070] The spring element 32 comprises a temperature-independent spring snap disc, which, with a central opening provided therein, is also fitted over the movable contact element 34, but from an opposite underside. The two snap discs 30, 32 are thus fitted over the movable contact element 34 from opposite sides.

[0071] The spring-loaded snap disc 32 carries in the in Fig. 1 In the low-temperature position of the switch 10 shown, the movable contact part 34 is pressed from below by its inner edge 36 against a circumferential, annular collar 38 of the movable contact part 34. In this process, the spring-loaded snap disc 32 rests with its outer circumferential edge 42 on the inner base 44 of the lower part 16.

[0072] In this position of the switch 10, the bimetallic snap disc 30 preferably rests freely with its inner edge region 40 on the collar 38 of the movable contact part 34 from the opposite upper side. The outer, circumferential edge 46 of the bimetallic snap disc 30 hangs freely into the interior of the housing 12. Thus, in this type of switch 10, the bimetallic snap disc 30 is mounted in the switch housing 12 with virtually no force, without being firmly clamped within it.

[0073] The temperature-dependent switching mechanism 14 is located in the Fig. 1 In the low-temperature position of the switch 10 shown, an electrically conductive connection is established between the two electrodes 50, 52 of the switch 10 by pressing the movable contact part 34 against a stationary contact part 48 arranged on the cover part 18. The contact pressure with which the movable contact part 34 is pressed against the stationary contact part 48 in the low-temperature position of the switch 10 is effected in the switch 10 by the spring-loaded snap disc 32.

[0074] Parts of the switch housing 12 serve as electrodes 50, 52, between which the temperature-dependent switching mechanism 14 establishes the electrically conductive connection in the low-temperature position of the switch 10. More precisely, in the switch 10 shown here, the stationary contact part 48 functions as the first electrode 50 and the lower part 16 of the switch housing 12 or the inner base 44 of the lower part 16 as the second electrode 52.

[0075] Starting from the in Fig. 1 In the low-temperature position of switch 10 shown, if the temperature of the device to be protected, and thus the temperature of switch 10 and the bimetallic snap disc 30 arranged therein, falls to the response temperature of the switching mechanism 14, which corresponds to the response temperature of the bimetallic snap disc 30, or exceeds this response temperature, the bimetallic snap disc 30 snaps from its position in Fig. 1 The convex low-temperature configuration shown transforms into its concave high-temperature configuration, which is shown in Fig. 2 As shown. During this snapping action, the bimetallic snap disc 30 rests with its outer edge 46 against the underside 54 of the cover part 18. With its center or inner edge region 40, the bimetallic snap disc 30 pushes the movable contact part 34 downwards and lifts the movable contact part 34 from the stationary contact part 48. Simultaneously, the spring snap disc 32 bends downwards at its center, so that the spring snap disc 32 is released from its position in Fig. 1 shown, first geometric configuration in their in Fig. 2 The second geometric configuration shown snaps into place. The electrically conductive connection previously established via the switching mechanism 14 between the two electrodes 50, 52 of the switch 10 is thus interrupted.

[0076] The temperature-dependent switching mechanism 14 is thus configured to establish and break the electrically conductive connection between the two electrodes 50, 52 depending on the temperature. Below the response temperature of the bimetallic snap disc 30, the switching mechanism 14 is in its in Fig. 1 The low-temperature position shown, in which it establishes the electrically conductive connection between the two electrodes 50, 52. As soon as the response temperature of the bimetallic snap disc 30 is exceeded, the bimetallic snap disc 30 moves the switching mechanism 14 into the position shown. Fig. 2 The high-temperature position shown, in which the electrically conductive connection between the two electrodes 50, 52 is interrupted.

[0077] Fig. 5 Figure 101 schematically shows, in the form of a simplified flowchart, the steps for the manufacture / assembly of such a temperature-dependent switch 10 according to the invention. In the first step S101, the switch housing 12 with the switching mechanism 14 arranged therein is provided. This first step S101 comprises inserting the switching mechanism 14 into the switch housing 12 and closing the switch housing 12 to protect the switch. Fig. 1 and 2 to produce the assembly state of switch 10 as shown.

[0078] Subsequently, in step S102, the switching mechanism 14 is intentionally heated to a temperature above the response temperature of the bimetallic snap disc 30 in order to engage the switching mechanism 14 in its Fig. 2 to bring the switch mechanism 14 into the open position shown. In this open position, the first external connection is then bonded to the first electrode 50 of the switch 10 in step S103.

[0079] Fig. 3 Figure 1 schematically illustrates the sequence of this assembly process using the example of an automated assembly process in which a large number of such temperature-dependent switches 10 are mounted one after the other on a moving conveyor belt 56. The first process step S101, the provision of the switch housing 12 with the switching mechanism 14 arranged therein, is shown in Figure 10. Fig. 3 not explicitly shown, as this can be implemented in the conventional way, either automatically or manually. Fig. 3 In particular, it visualizes the assembly process during process steps S102 and S103.

[0080] At the in Fig. 3 In the schematically shown assembly process, the individual switches 10 with their respective switch housings 12 are each individually attached to the conveyor belt 56 to prevent slippage or even loss of the switches 10. Preferably, the switches 10 are bonded to the conveyor belt 56. The conveyor belt 56 has a plurality of receptacles 58 for this purpose, as shown in particular in Fig. 4 This can be seen in the figure showing the conveyor belt 56 without the switches 10 inserted therein in a top view from above.

[0081] The receptacles 58 are annular receptacles into which the switches 10 are inserted from above. The receptacles 58 are preferably adapted to the diameters of the lower parts 16 of the switch housings 12. As in Fig. 1 and 2As shown, the lower part 16 of each switch 10 has a recessed circumferential shoulder 60 on the underside, into which the annular receptacle 58 is fitted precisely and is preferably soldered or welded to it.

[0082] Each of the recordings 58 also has a connecting piece 62 which, as subsequently explained in detail, essentially serves to attach the second external connection of the respective switch 10.

[0083] During the assembly process, the conveyor belt 56 is moved in the direction of arrow 64, so that the switches 10 attached to the conveyor belt 56 go through the individual assembly steps explained below in succession.

[0084] First, the second external connection 66, which is in the form of a cable lug, a terminal, a connecting cable, or a connecting wire, is electrically connected to the second electrode 52 of the switch 10. For this purpose, the second external connection 66 is welded or soldered to the connecting piece 62, which in turn is attached to the lower part 16 or the second electrode 52. This is in Fig. 3 schematically indicated with the help of a first welding gun 68.

[0085] The second external connection 66 is attached in the low-temperature position of the switch 10. This has the advantage of ensuring the greatest possible distance between the movable contact part 34 of the switching mechanism 14 and the weld point where the second external connection 66 is attached. The risk of the movable contact part 34 melting to the stationary contact part 48 due to the heat generated is thus reduced to a minimum.

[0086] Subsequently, the switches 10 are brought into the high-temperature position by external heating, in which the respective switching mechanism 14 is in its Fig. 2 The open position shown is located. This is achieved in the present case by guiding the switches 10 through a heating tunnel or heating section 70. One or more external heat sources 72 are provided at this heating section 70, which are in Fig. 3 are schematically represented by heating wires. However, it is understood that the heat sources 72 can be any type of heat source, for example hot air heat sources, infrared heat sources, inductive heat sources, etc.

[0087] Preferably, the switches within the heating section 70 are continuously heated by the heat sources 72 to a temperature above the switching mechanism's response temperature. Typically, heating to a temperature greater than 100 °C is sufficient, for example, heating to a temperature in the range of 150–270 °C.

[0088] After passing through the heating section 70, the switching mechanisms 14 of all switches 10 are accordingly in their open or high-temperature position. While the switching mechanisms 14 of the switches 10 are in this open position, as shown in the right edge of the image. Fig. 3 As shown, the first external connection 74, which is also implemented in the form of a cable lug, a connecting wire, a regular cable or a connecting tab, is welded or soldered to the top of the stationary contact part 48, which functions as the first electrode 50. This process is described in Fig. 3 schematically illustrated using a second welding gun 76.

[0089] As particularly through a combination of Fig. 2 As can be seen, the movable contact part 34 of the switching mechanism 14 has a maximum distance from the stationary contact part 48 in the open position. Furthermore, there is no direct mechanical or thermal contact between the two contact parts 34 and 48. Accordingly, the risk of the two contact parts 34 and 48 melting together due to the heat generated when the first external connection 74 is attached is reduced to a minimum. The fragile components 30, 32, and 34 of the switching mechanism 14 are thus optimally protected against damage that could otherwise occur due to the extremely high heat generated inside the switch housing 12.

[0090] The method according to the invention thus enables automated assembly / production of temperature-dependent switches, which allows for stable and sustainable attachment of the external connections 74, 66 and at the same time provides the best possible protection for the temperature-dependent switching mechanism 14 provided in the switch.

[0091] As already mentioned, the assembly method according to the invention is not only suitable for a temperature-dependent switch 10, as it is in Fig. 1 and 2 shown schematically, but also for various other temperature-dependent switches with similar / comparable switching characteristics.

Claims

1. A method for assembling a temperature-dependent switch (10), including the steps: (i) providing a switch housing (12) having a first and a second electrode (50, 52) and a temperature-dependent switching mechanism (14) arranged in the switch housing (12), wherein the switching mechanism (14) is configured to switch in a temperature-dependent manner between a closed state, which the switching mechanism (14) assumes below a response temperature and in which the switching mechanism (14) establishes an electrically conductive connection between the first and the second electrode (50, 52), and an open state, which the switching mechanism (14) assumes above the response temperature and in which the switching mechanism (14) disconnects the electrically conductive connection; characterized by the following steps: (ii) heating the switching mechanism (14) to a temperature above the response temperature to bring the switching mechanism (14) in the open state; and (iii) attaching, by material-locking joining, a first external terminal (74) to the first electrode (50) or to a part electrically connected with the first electrode (50), while the switching mechanism (14) is in the open state.

2. The method according to claim 1, wherein the attaching of the first external terminal (74) by the material-bonded connection comprises a soldering process or a welding process.

3. The method according to claim 1 or 2, wherein the switching mechanism (14) is heated to the temperature above the response temperature by heating the switch housing (12) and the switching mechanism (14) arranged therein by an external heat source.

4. The method according to any one of claims 1-3, wherein the temperature to which the switching mechanism (14) is heated is higher than 100 °C.

5. The method according to any one of claims 1-4, wherein the switching mechanism (14) is heated to the temperature above the response temperature passing the switch housing (12) and the switching mechanism (14) arranged therein in an automated manner through a heating section (70).

6. The method according to claim 5, wherein the attaching of the first external terminal (74) by material-locking joining with the application of heat is performed in an automated manner after passing through the heating section (70).

7. The method according to any one of claims 1-6, wherein the method further comprises the step of: (iv) attaching, by material-locking joining with the application of heat, a second external terminal (66) to the second electrode (52) or to a part electrically connected to the second electrode (52).

8. The method according to claim 7, wherein step (iv) is carried out before step (ii).

9. The method according to any one of claims 1-8, wherein the switch housing (12) comprises a lower part (16) and a cover part (18) closing the lower part (16) and electrically insulated from the lower part (16), wherein the cover part (18) is at least partly made of electrically conductive material, and wherein the first electrode (50) is arranged on the cover part (18).

10. The method according to claim 9, wherein the first electrode (50) comprises a contact part (48) which extends from the inside of the switch housing (12) through the cover part (18) to the outside.

11. The method according to any one of claims 1-10, wherein steps (i)-(iii) are repeated for a plurality of temperature-dependent switches (10), and wherein the switch housings (12) of the plurality of temperature-dependent switches (10) are fixed to a common conveyor belt (56) while steps (i)-(iii) are carried out.

12. The method according to claim 11, wherein the conveyor belt (56) comprises a plurality of receptacles (58), to each of which one of the switch housings (12) of the plurality of temperature-dependent switches (10) is fixed, and wherein each of the plurality of receptacles (58) comprises a connecting piece (62) which is electrically connected to the second electrode (52) of the respective switch housing (12) and to which the second external terminal (66) is attached by material-locking joining with the application of heat.

13. The method according to any one of claims 1-12, wherein the temperature-dependent switching mechanism (14) comprises a bimetal part (30).

14. The method according to claim 13, wherein the temperature-dependent switching mechanism (14) comprises a spring part (32) interacting with the bimetal part (30).

15. The method according to claim 14, wherein the bimetal part (30) is a temperature-dependent bimetallic snap-action disc and the spring part (32) is a temperature-independent snap-action spring disc.