Overload protection device for the protection of electrical components

Abstract

The invention relates to an overload protection arrangement (1) for protecting electrical components (2), comprising at least two electrical components (2), a carrier (3) having several connection elements (31) for connecting the electrical components (2), and at least one actuator (4), wherein the overload protection arrangement (1) is characterized in that at least one disconnecting element (6) is slidably arranged on the carrier (3), that the disconnecting element (6) is acted upon by an actuator (4) with a force (F) such that the disconnecting element (6) can be moved by the actuator (4) from a first position to a second position, and that the disconnecting element (6) interacts with two electrical components (2) in such a way that the two electrical components (2) can be moved into their second position in the event of a thermal overload by the disconnecting element (6).

Description

[0001] The invention relates to an overload protection arrangement for the protection of electrical components, comprising at least two electrical components, a carrier having several connection elements for connecting the electrical components, and at least one actuator according to the preamble of claim 1.

[0002] In the overload protection arrangement, the electrical components are each fixed to the carrier in a first position by means of a thermally softenable fixing, such that the terminals of the electrical components contact the corresponding terminals of the carrier. In the event of a thermal overload of the electrical components, the thermally softenable fixing softens, and the electrical components are moved by the force of the actuator into a second position in which the electrical contact between the electrical components and the corresponding terminals of the carrier is broken. The electrical components are thus electrically disconnected in their second position.

[0003] Electrical components are generally only permitted to operate within a specific voltage range and with a specific (maximum) current, i.e., within a rated operating range. Overloading electrical components can cause them to operate outside their rated operating range. For example, the increased power dissipation at a damaged component, caused by reduced insulation strength, can lead to impermissible heating of the component. If this impermissible heating is not stopped and further heating is prevented, the component can be completely destroyed. This can lead to damage to surrounding materials and equipment, the generation of fumes, or a fire hazard.Therefore, it is common practice to assign thermal fuses to electrical components in order to enable the shutdown of an electrical component in case of excessive heating.

[0004] The disconnection of overloaded electrical components has been implemented for years, particularly in surge protection systems. Surge protection systems have been used for decades in various designs to protect electrical circuits, systems, machines, and equipment. Depending on the application and protection level, these systems incorporate different surge protection elements and have different designs. Surge protection elements can include surge-limiting components such as varistors or transient absorber diodes (TVS diodes), as well as surge-switching components such as spark gaps or gas discharge tubes (GDTs), and combinations of these components. When using varistors as surge protection elements, it is common practice to incorporate thermally activated disconnect devices.For gas discharge tubes, solutions are known that short-circuit the component after thermal overload, thus reducing the power consumption in the overloaded gas discharge tube.

[0005] From DE 20 2011 110 007 U1, it is known to arrange a surge protection device, which may in particular be a varistor, on a carrier, wherein the two terminals of the varistor are each connected via a thermosensitive solder connection to a terminal element on the carrier and thereby to the circuit to be protected. In the event of a thermal overload of the varistor, the solder connections melt and the varistor is moved into a second position by an actuator, which may in particular be a spring element. In the second position, the terminals of the varistor are disconnected from the terminal elements on the carrier, so that, as a result, the varistor is disconnected from the circuit.

[0006] DE 10 2016 209 365 B4 discloses a disconnecting device for two electronic components, each of which is attached to a carrier by a thermally softenable fixing, in particular a solder or an adhesive, wherein each electronic component is assigned a spring as an actuator. If a thermally softenable fixing softens due to impermissible heating of a component, the spring displaces the associated electronic component parallel to the carrier, so that the component, which may be a varistor, a diode or a gas-filled surge arrester, is electrically disconnected.

[0007] DE 10 2019 114 424 A2 discloses, in an embodiment, an overload protection arrangement as described above, comprising two surge protection elements, each of which is moved along a carrier by a spring element when a thermally softenable fixing has broken due to heating of the surge protection element. Only one electrical contact between the surge protection element and the associated connection element of the carrier is broken, while the other contact is maintained via a second connection element. For this purpose, the second connection element is designed such that it allows the movement of the surge protection element from the first position to the second position, for example by changing its shape.This has the advantage that the surge protection element is also mechanically connected to the carrier via the second connection element in the second position, so that the surge protection element does not move uncontrollably in the environment, for example in a housing, after being disconnected on one side.

[0008] Based on this prior art, the invention aims to provide an overload protection arrangement that is particularly simple in design. In particular, the temperature-dependent isolation of several electrical components should be achieved as simply as possible.

[0009] This problem is solved in the overload protection arrangement with the features of claim 1 in that the overload protection arrangement has at least one separating element which is slidably arranged on the support. The separating element is subjected to a force by an actuator such that the separating element can be moved by the actuator from a first position to a second position. In addition, the separating element interacts with two electrical components in such a way that, in the event of a thermal overload, the two electrical components can be moved by the separating element into their second position when the thermal fixation softens, so that the electrical components are no longer held in their first position against the force of the actuator.

[0010] By using the disconnecting element, the force of one actuator can be transferred to two electrical components, so that only one actuator is required to disconnect two electrical components instead of two. The actuator can be, in particular, a spring element, preferably a compression spring, which exerts a force on the disconnecting element, at least in its first position. If a compression spring is used as the actuator, it is thus deflected against its spring force in the first position of the disconnecting element, i.e., compressed, while the compression spring is at least partially relaxed in the second position of the disconnecting element. Preferably, the disconnecting element and the actuator or spring element are arranged relative to each other such that a force—at least a small one—still acts on the disconnecting element in the second position, thus securely holding the disconnecting element in its second position.

[0011] It is stated at the outset that the overload protection arrangement comprises, in addition to a support, at least two electrical components, at least one actuator, and at least one disconnect element. In principle, the overload protection arrangement can comprise only two electrical components, one actuator, and one disconnect element. Preferably, however, the overload protection arrangement comprises n actuators, n disconnect elements, and (2 x n) electrical components, where n ≥ 2. The overload protection arrangement thus preferably comprises two actuators, two disconnect elements, and four electrical components, with each actuator interacting with one disconnect element and each disconnect element interacting with two electrical components. A disconnect element thus disconnects a pair of electrical components simultaneously if the thermal fixation softens due to impermissible heating of the two components.

[0012] The electrical components that are disconnected by the at least one disconnecting element in the event of impermissible heating are in particular overvoltage protection elements, whereby both overvoltage limiting components such as varistors or transient absorber diodes (TVS diodes) and overvoltage switching components such as spark gaps or gas discharge tubes (GDTs) as well as combinations of these components can be used as overvoltage protection elements.

[0013] A low-temperature solder is preferably used as a thermally softenable fixing agent. This solder melts or softens when the component in contact with it is subjected to thermal overload above a certain temperature. Preferably, the connections of the individual components in their first position, when the components are not overloaded, are electrically and mechanically connected to a terminal element on the carrier via such a solder connection. Alternatively, an electrically conductive adhesive can also be used to connect the connections of the individual components to the corresponding terminal element on the carrier.

[0014] According to a preferred embodiment of the invention, the two electrical components that interact with a separating element, and thus are subject to the force of an actuator, are thermally coupled. This results in the thermally softenable fixing of both electrical components softening in the event of a thermal overload of at least one of the two electrical components, allowing both electrical components to be moved into their second position. The thermal coupling of the two electrical components ensures that a thermally overloaded component is electrically disconnected, even if the other electrical component, which interacts with the thermally overloaded component and a separating element, is not yet overloaded.

[0015] Furthermore, it is also possible that the thermally softenable fixing serves only for the mechanical fixing of the components to the substrate and not simultaneously for the electrical connection of the components. In this case, a thermally softenable fixing may be provided for one component or for a pair of components.

[0016] In the context of the present invention, the carrier is in particular designed as a printed circuit board (PCB) in which the connection elements for the electrical components are connected to conductor tracks of the PCB. The electrical components, in particular surge protection elements, can then be connected to the current or signal path to be protected via the conductor tracks of the PCB.

[0017] To prevent the two electrical components that interact with a separating element, or are moved by the separating element from their first position to their second position, from becoming electrically connected via the separating element, the separating element preferably consists of, or incorporates, an insulating material. It is generally sufficient if only the areas of the separating element in contact with the electrical components are made of insulating material. Alternatively, the separating element can also consist of two electrically conductive areas, each in contact with an electrical component, with the two electrically conductive areas being insulated from each other by a plastic section. Preferably, however, the separating element consists entirely of an insulating material, making it easy to manufacture, for example, by injection molding.

[0018] According to an advantageous embodiment of the invention, the separating element has a receptacle, at least for the end of the actuator facing the separating element. The receptacle, which can be designed, for example, as a dome, serves to hold the actuator in the desired position after it has been mounted on the circuit board. Furthermore, the receptacle ensures that the actuator, in particular a corresponding spring element, maintains reliable contact with the separating element even when the separating element is moved from its first position to its second position by the force of the actuator.

[0019] According to a further advantageous embodiment, the separating element has a support section for at least one section of the actuator, such that the actuator rests at least partially on the support section. This ensures that the actuator does not touch the surface of the carrier facing the actuator, even when the separating element is moved from its first position to its second position by the force of the actuator. This design of the separating element particularly ensures that an actuator does not come into contact with live sections on the carrier, such as conductor tracks on a printed circuit board. This makes it possible to use a simple metallic spring element for the actuator without requiring an insulating covering.

[0020] Advantageously, the at least one separating element is designed and arranged such that it guides the two electrical components along the surface of the carrier from their first position to their second position. Preferably, the separating element itself also moves substantially parallel to the surface of the carrier, which, due to the design of the separating element, results in a corresponding movement of the electrical components parallel to the surface of the carrier. For this purpose, at least one guide element can be formed on the separating element, which interacts with a corresponding guide element on the carrier.

[0021] The separating element is advantageously designed and arranged such that the two electrical components are not only moved from their first position to their second position along a predetermined path along the surface of the carrier, but the separating element also ensures that the two separated electrical components remain in their second position. This can be achieved, for example, by pressing the two separated electrical components against a stop or another component in their second position, so that the electrical components cannot move uncontrollably in their surroundings, for example, within a housing.

[0022] To achieve the previously described guided movement of two electrical components, the separating element, according to a preferred embodiment, has two contact surfaces for the two electrical components on the side facing them. The dimensions of these contact surfaces are adapted to the corresponding end face or side surface of an electrical component, ensuring secure contact between the electrical components and the contact surfaces of the separating element. The two contact surfaces are preferably arranged at an angle α > 180° to each other, preventing the two electrical components from moving towards each other when they are moved from their first to their second position.Furthermore, recesses or ridges can be formed on the mounting surfaces, which can additionally prevent movement of the electrical components perpendicular to the direction of movement of the separating element.

[0023] Alternatively or additionally, a separating element can be provided on the side of the separating element facing the two electrical components. This separating element keeps the two electrical components apart when they are moved from their first position to their second position. The separating element is specifically arranged between the two contact surfaces and can be web-shaped or pin-shaped. The two previously described configurations of the separating element, which can be implemented individually or together, ensure that the two electrical components do not come into unintentional contact, particularly when moving them from their first to their second position.

[0024] In a preferred design, the separating element has an essentially U-shaped basic form. The back of the U-shaped element faces the two electrical components, so that the contact surfaces for the two components are formed on the back of the U. On the side of the back of the U facing away from the electrical components, the two legs of the U extend away from them. The legs of the U can be designed as guide arms that guide the separating element when it is moved from its first position to its second position. If the separating element has a divider, this is arranged on the side of the back of the U opposite the legs of the U and extends between the two electrical components.

[0025] According to a further advantageous embodiment of the previously described separating element, the dimensions of the separating element, in particular the distance between the two guide arms or U-shaped legs, are selected such that the actuator is arranged between the two guide arms, at least in the first position of the separating element. This design of the separating element and arrangement of the actuator between the two guide arms enables a very compact arrangement of the actuator and the separating element on the support. Furthermore, it also makes it possible for the separating element with its two guide arms to be guided by the actuator or by a bracket that receives the actuator, thereby reducing the number of components required.

[0026] As previously explained, the overload protection arrangement according to the invention preferably comprises not just two electrical components, but at least four electrical components arranged in pairs, such that each pair of components is assigned to a disconnect element. Furthermore, regardless of the number of electrical components, the overload protection arrangement preferably comprises a housing in which the carrier with the electrical components, the disconnect elements, and the actuators is at least partially arranged.

[0027] In a particularly preferred embodiment of an overload protection arrangement with two actuators, two disconnect elements, and four electrical components, the arrangement also includes an indicator element whose position indicates whether at least one disconnect element or a pair of electrical components is in the first or second position. The housing has a viewing window through which it is possible to see whether the indicator element is in its first or second position.

[0028] The aforementioned display element is preferably designed as a slider, wherein the display element is arranged on the side of the electrical components facing away from the separating elements in such a way that the display element or the slider is moved from a first position to a second position when at least one of the two separating elements is moved into its second position due to a thermal overload of the two associated electrical components.

[0029] In this preferred embodiment, the display element is moved by the force of the actuators, which also exert force on the separating elements. Preferably, the force transmission occurs from an actuator via the associated separating element and the electrical components interacting with the separating element. However, the force transmission can also occur directly from an actuator via the associated separating element to the display element. The separating element is then designed such that it is in contact with both associated electrical components as well as (directly) with the display element.

[0030] In detail, there are several ways to design and further develop the overload protection arrangement according to the invention. Reference is made to the dependent claims and the following description of preferred embodiments in conjunction with the drawing. The drawing shows Fig. 1 An embodiment of an overload protection arrangement with two disconnect elements in the first position, Fig. 2 the overload protection arrangement according to Fig. 1, with the first separating element in the second position, Fig. 3 the overload protection arrangement according to Fig. 1, with the second separating element in the second position, Fig. 4 the overload protection arrangement according to Fig. 1, with both separating elements in the second position, Fig. 5 an enlarged section of the overload protection arrangement according to Fig. 1 with two electrical components and a separating element in their first position, Fig. 6 a perspective view and a top view of a first embodiment of a separating element, and Fig. 7 a perspective view and a top view of a second embodiment of a separating element.

[0031] The Fig. Figures 1 to 4 show a preferred embodiment of an overload protection arrangement 1 with a total of four electrical components 2, which are arranged on a carrier 3 designed as a printed circuit board. Fig. Figure 5 shows an enlarged section of the overload protection arrangement 1 according to Fig. 1 with two electrical components 2. In the illustrated embodiment, the electrical components 2 are each gas discharge tubes, although the invention is not limited to this. The two terminals 21 of the components 2 are each electrically and mechanically connected to corresponding connection elements 31 on the carrier 3 via a solder connection as a thermally softenable fixing. In the illustration according to the Fig. In figures 1 to 4, the connection elements 31 are located below the connections 21 of the components 2, so that the connection elements 31 are not visible in the figures.

[0032] Fig. Figure 1 shows the state of the overload protection arrangement 1 in which all electrical components 2 are in their normal state, i.e., not excessively heated, so that the components 2 are in their first position, in which the terminals 21 are electrically and mechanically connected to the individual terminal elements 31 on the carrier 3 via the individual solder connections. The individual components 2 are thus electrically connected to the carrier 3 or its conductor tracks.

[0033] In addition to the four electrical components 2, two actuators 4, designed as spring elements and each arranged in a holder 5, and two separating elements 6 are arranged on the carrier 3. While the holders 5 of the actuators 4 are fixedly arranged on the carrier 3, the two separating elements 6 are each slidably arranged on the carrier 3. Each separating element 6 is subjected to a force F by an actuator 4. Furthermore, each of the two separating elements 6 interacts with two electrical components 2 in such a way that, in the event of thermal overload, the associated separating element 6 moves two electrical components 2 into their second position when the thermal fixation softens, so that the electrical components 2 are no longer held in their first position against the force F of the actuator 4 acting on the separating elements 6.The force F of an actuator 4 is thus transferred to two electrical components 2 by means of the separating elements 6 arranged between each of the two electrical components 2 and an actuator 4.

[0034] The Fig. 2 and Fig. Figures 3 each show the state of the overload protection arrangement 1 in which two electrical components 2 are in their normal state, i.e., not excessively heated, so that these components 2 are in their first position, while the solder joint of the other two electrical components 2 has broken, so that these components 2 have been moved into their second position by the separating element 6. Similarly, one separating element 6 is in its first position, while the other separating element 6 has been moved into the second position by the force F of the actuator 4.

[0035] Fig. Figure 4 shows the state of the overload protection arrangement 1 in which all electrical components 2 have overheated to an impermissible degree, such that all solder connections have broken and all four electrical components 2 are in their second position, in which the components 2 are electrically disconnected, since the terminals 21 of the components 2 are no longer connected to the terminal elements 31 on the carrier 3. Because the electrical components 2 have been moved into their second position in pairs by the disconnecting elements 6, the two disconnecting elements 6 are also in their second position.

[0036] Fig. Figure 6 shows a first embodiment of a single separating element 6 in perspective view ( Fig. 6a) or in top view ( Fig. 6b). In the illustrated embodiment, the separating element 6, which consists of an insulating material, has a receptacle 61 for the end of the actuator 4 facing the separating element 6. This ensures that the actuator 4 is held in its position on the separating element 6 after its installation in the holder 5, even when the separating element 6 is in its second position. Thus, even in the second position of the separating element 6, at least a small force can still be applied to the separating element 6, thereby holding the separating element 6 in its second position.

[0037] Furthermore, the separating element 6 has a support section 62 for a section of the actuator 4, so that the actuator 4 does not touch the surface of the carrier 3, even when the separating element 6 is moved from its first position to its second position by the force F of the actuator 4. This ensures that the actuator 4, designed as a metallic spring element, does not touch any stress-carrying sections on the carrier 4.

[0038] To ensure the safe guidance of two electrical components 2 from their first position to their second position by means of a separating element 6, the separating element 6 has two contact surfaces 63 for the two electrical components 2 on its side facing the two electrical components 2. From the top view according to Fig. As can be seen in Figure 6b, the two contact surfaces 63 are arranged at an angle α to each other of slightly more than 180°. The two contact surfaces 63 are thus inclined slightly backwards from the center of the separating element 6, viewed in the direction of movement of the separating element 6 from its first position to its second position. Furthermore, a rib-shaped separating element 64 is formed on the separating element 6 between the two contact surfaces 63, extending between the two electrical components 2 adjacent to the separating element 6. This ensures that the two electrical components 2 do not come into unintended contact when they are moved from their first position to their second position.

[0039] The in Fig. The separating element 6 shown in Figure 6 has an essentially U-shaped basic form. The back 65 of the separating element 6 faces the two electrical components 2, so that the two contact surfaces 63 for the two components 2 are formed on the back 65. On the opposite side of the back 65, facing away from the electrical components 2, the two legs of the U extend away from the electrical components 2. The separating element 64 is arranged on the side of the back 65 opposite the legs of the U and extends between the two electrical components 2.

[0040] The U-shaped legs are designed as guide arms 66, 67, which serve to guide the separating element 6 when moving it from its first position to its second position. For this purpose, the guide arms 66, 67 of a separating element 6 slide with their inner surfaces along the outer surfaces of the holder 5 of the actuator 4, as shown in the Fig. 1 to 4 can be seen. The bracket 5 and the actuator 4 are thus arranged between the guide arms 66, 67 of a separating element 6, which enables a very space-saving arrangement of the two actuators 4 with their respective bracket 5 and the two separating elements 6 on the carrier 3.

[0041] As from Fig. 6a and Fig. As can be seen in Figure 6b, one guide arm 66 is longer than the other guide arm 67. The different lengths of the guide arms 66 and 67 can be used as a positioning aid for the separating element 6, so that the separating element 6 is mounted on the carrier 3 in a predetermined orientation. Furthermore, the greater length of one guide arm 66 can be used to actuate a microswitch (not shown in the figures) arranged on the carrier 3, so that the microswitch can provide an electrical indication of whether a separating element 6 is in its first or second position. Thus, a remote indication of whether a pair of electrical components 2 has been disconnected or not is possible via such a microswitch.

[0042] Fig. Figure 7 shows a second embodiment of a single separating element 6 in perspective view ( Fig. 7a) or in top view ( Fig. 7b). In contrast to the embodiment according to Fig. In this separating element 6, no separating element is arranged between the two mounting surfaces 63. Instead, the [element] in Fig. The separating element 6 shown in Figure 7 has a significantly extended support section 62 for a section of the actuator 4, compared to the support section 62 of the separating element 6 according to Figure 7. Fig. 6. Furthermore, the two guide arms 66, 67 of the separating element 6 exhibit according to Fig. 7 the same length.

[0043] The in the Fig. The overload protection arrangement 1 shown in Figures 1 to 4 also has a housing 7 in which the carrier 3 with the electrical components 2, the actuators 4 and the isolating elements 6, as well as a display element 8, are at least partially arranged. A viewing window 71 is formed in the housing 7, through which it is possible to see from outside the housing 7 whether the display element 8 is in its first position ( Fig. 1) or in its second position ( Fig. 2 to 4). The display element 8 is designed as a slider with a display section 81 that is pushed in front of the viewing window 71 when at least one of the two pairs of components 2 or one of the two separating elements 6 is moved from the first to the second position. The display element 8 thus indicates whether all electrical components 2 are electrically connected ( Fig. 1) or at least one pair of components 2 has separated due to impermissible heating ( Fig. 2 to 4).

[0044] The display element 8 is arranged on the side of the electrical components 2 facing away from the separating elements 6 such that the display element 8 is moved from a first position to a second position when at least one of the two separating elements 6 is moved into its second position due to a thermal overload of the two associated electrical components 2. Furthermore, the display element 8 is arranged relative to the electrical components 2 in the housing 7 such that the components 2, in their second position, are pressed against the display element 8 by the associated separating element 6, thus holding the components 2 in their second position.

[0045] The display element 8 also has a flexible retaining element 82 which interacts with the separating elements 6 such that the display element 8 is held in its first position when both separating elements 6 are in their first position. For this purpose, the separating elements 6 have retaining sections 68 against which the retaining element 82 rests, as shown in the figure. Fig. 1 is evident. Because the retaining element 82 is flexible, the indicator element 8 can slide past the second separating element 6 when a separating element 6 is moved from its first position to its second position, even if the second separating element 6 remains in its first position ( Fig. 2 and Fig. 3) For this purpose, the corresponding holding sections 68 on the separating elements 6 have rounded corners, so that the holding element 82 can slide past the holding sections 68 more easily. Reference sign 1 Overload protection arrangement 2 electrical component 21 connections 3 carriers 31 Connection element 4 Actuator 5 bracket 6 separating element 61 recording 62nd edition section 63 Plant area 64 separating element 65 U-back 66 U-leg (guide arm) 67 U-leg (guide arm) 68 holding sections, holding element 82 7 cases 71 viewing windows 8 Display element 81 Display section 82 retaining element α Angle between the mounting surfaces 61 QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 20 2011 110 007 U1

[0005] DE 10 2016 209 365 B4

[0006] DE 10 2019 114 424 A2

[0007]

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