HK1184278B - Thermal overload protection apparatus - Google Patents

Description

Thermal overload protection device

Technical Field

The invention relates to a thermal overload protection device for protecting electrical components, in particular electronic components, comprising: a switching element for short-circuiting the connection points of the component or for breaking an electrically conductive connection between at least one of the connection points and a current-carrying element of the overload protection device; actuator means for switching the switching element to the appropriate short-circuit position or open position; and a tripping element (tripping element) for thermally tripping the actuator device.

Background

An overload protection device of this type is described, for example, in german patent publication DE102008022794 Al. Said document describes a thermal overload protection device comprising: a shorting device having a shorting bar (shorting bar) elastically biased for shorting electrodes of a lightning arrester (surge arrester); and a fusible element for tripping the overload protection device. As overload protection means for the switching element with the short-circuit device, in addition to this embodiment, overload protection means with the corresponding switching element of the disconnection device are also conceivable.

Overloading of an electronic component can cause the component to operate outside of the nominal operating range. In this case, the heat generation may be increased by power conversion at the damaged component, for example, due to a reduction in the dielectric strength of the component. If the component is not prevented from being heated above the allowed threshold value, this may for example result in damage to surrounding materials, the generation of exhaust gases, or the risk of fire.

These hazards also exist in devices that place components (e.g., surface mountable components) on a conductive track support. To construct this type of device, conductive track supports (printed circuit boards (PCBs)) are assembled with appropriate components and soldered, typically by an automated machine. Due to this assembly process, there is often only a very limited installation space. At the same time, a temperature is locally generated, which reaches at least approximately the tripping temperature of the tripping element.

Disclosure of Invention

It is an object of the present invention to provide a thermal overload protection device which requires little installation space, can reliably short-circuit or open in response to a thermal overload, and can be easily integrated on a conductive rail support despite the temperatures that occur during the installation of the installation operation of the component, in particular in the surface mounting of the component.

According to the invention, this object is achieved by the features set forth in the independent claims. Preferred embodiments of the invention are disclosed in the dependent claims.

In the overload protection apparatus of the present invention, the actuator means may be switched to be activated from an inactive state in which the actuator means cannot switch the switching element even by tripping the tripping element to a tripped state in which the switching element can be switched by the actuator means tripped by the tripping element. Thus, in this context, the terms "inactive" and "tripped" mean that only the actuator device activated by switching exerts the force required for short-circuiting or opening during tripping, while the non-activated (i.e. inactive) actuator device does not exert any force or does not exert a force sufficient for short-circuiting or opening, even when tripping is performed by means of a tripping element. Overload protection devices of this type can be installed without risk of tripping, even when installed by installation types associated with high temperatures, such as welding. Thus, activation may only be achieved after a non-critical temperature is reached or at any other optional time. In particular, this time may be the end of the installation of the overload protection device and/or the electrical component.

The component is preferably a component which is mountable on or via its connection point to a conductive track support comprising a conductive track. In particular, the current carrying element, which is formed as an electrically conductive connection in the electrical switching element of the disconnection element, is one of the conductive tracks or a current carrying element mounted on a conductive track support and connected to one of the conductive tracks. The electrically conductive connection is a connection for connecting the components. The short-circuit is in particular a short-circuit formed via at least one of the conductive tracks.

The trip element is preferably formed as a fusible element which is tripped by melting. The melting point of the fusible element determines the trip temperature, and thus the trip temperature can be set by material selection. The fusible element has, for example, solder or hot-melt plastic as the active material.

Hot melt plastics exhibit a softer firm transition at the melting point than solder. This has the following advantages: the trip element made of hot-melt plastic maintains its original position even when tripping occurs, and only the tripping operation is performed to change the shape of the trip element so that the short-circuiting device can short-circuit the assembly.

If the switching element is formed as a disconnection device for disconnecting at least one of the connection points from the electrically conductive connection of the current-carrying element, the fusible element is preferably a soldered joint in the electrically conductive connection (to be disconnected).

According to a preferred embodiment of the invention, the actuator means are the following actuator means: the actuator means may be switched by manually changing the profile of the actuator means or the arrangement of the actuator means relative to the switching element. Thus, the switching is a manual switching by changing the outer shape of the actuator means or the arrangement of the actuator means with respect to the switching element. The activation can take place directly at the overload protection. The user is free to choose the moment of activation.

According to a preferred embodiment of the invention, the actuator means has at least one elastic element, and the actuator means is in particular an elastic element. The actuator means is switched by biasing the resilient element.

In particular, in this case, the elastic element is or has a snap-in piece (snap dome). Snap-dome is an elastic element that functions according to the clicker principle. The sonotrode is an elastic element made of a strip of spring steel. The steel is stamped so that it has a stable state and a metastable state. In the steady state, the steel bends due to the influence of forces until it suddenly springs back into the metastable state by a depression. The resilient elements of the castellations typically have a dome-shaped or dome-shaped region formed by a stamping process. These two states are preferably used in this embodiment of the invention to create the relaxed state and the biased state of the resilient element. In this case, the switching is from a relaxed state to a biased state.

Alternatively or additionally, the actuator device may have as active material a dilatant material and/or a shape memory material and/or a material that chemically changes shape.

In particular, the actuator means in the switching state are mechanically biased actuator means by a latch at the switching element. Thus, certain components of the actuator device and/or the switching element may latch or otherwise positively engage with each other when the actuator device is switched to bias the actuator device.

Alternatively or additionally, the actuator means is preferably a device that is switchable (and thus activated) by reciprocal displacement of certain parts or regions of the actuator means. If the actuator device has an elastic element which acts by the snap principle (snap dome), the displacement is a depression of the region of such an elastic element.

According to a development of the invention, the switching element and the actuator device are formed in one piece or at least comprise a common part formed in one piece. This reduces the number of parts required and provides a neat connection between the switching element and the actuator device.

According to a preferred embodiment of the invention, the component is a component which is separable from the overload protection device, in particular from the switching element. The assembly and the overload protection can thus be actuated at least in principle independently of one another. In particular, this degree of freedom simplifies the assembly and/or the installation of the overload protection device.

The invention also relates to a device comprising a conductive track support, at least one component arranged on the conductive track support, and at least one overload protection device as described above. The component is preferably a lightning arrester, in particular a semiconductor-based lightning arrester (suppressor diode), varistor, etc., or a gas-filled lightning arrester or resistor.

In particular, the component is a surface mount component (SMD component) which is mounted on the conductive tracks of the conductive track support, preferably by means of a reflow soldering method.

According to a preferred embodiment of the invention, the switching element and/or the actuator device of the overload protection device is supported on the component via a tripping element (i.e. indirectly) or via a conductive track of a conductive track support which is directly connected to a connection point of the component. In particular, alternatively or additionally, the switching element and/or the actuator device of the overload protection device is supported directly on at least one conducting track in contact with one of the connection points.

Drawings

The invention will be explained in more detail hereinafter according to preferred embodiments with reference to the accompanying drawings, in which:

fig. 1A to 1C show schematic views of a thermal overload protection apparatus for breaking an electrical connection according to a first embodiment;

fig. 2 shows a plan view of an actuator arrangement of the thermal overload protection apparatus of fig. 1A-1C;

fig. 3A to 3C are schematic diagrams illustrating a thermal overload protection apparatus for breaking an electrical connection according to a second embodiment;

fig. 4 shows an electronic assembly and a thermal overload protection device in an inactive operating state according to a third embodiment of the present invention;

FIG. 5 shows the assembly of FIG. 4 and the thermal overload protection device in an activated operating state;

fig. 6 shows the assembly of fig. 4 and 5 and the thermal overload protection device in a tripped state;

fig. 7 shows an electronic assembly and a thermal overload protection device in an inactive operating state according to a fourth embodiment of the present invention;

FIG. 8 shows the assembly of FIG. 7 and the thermal overload protection device in an activated operating state; and

fig. 9 shows the assembly of fig. 7 and 8 and the thermal overload protection device in a tripped state.

Description of the main elements

10: overload protection device

12: switching element

14: conductive connection

16: current-carrying element

18: connection point

20: assembly

22: actuator device

24: trip element

26: fusible element

28: elastic element

30: strip-shaped region

32: strip-shaped region

34: strip-shaped region

36: end region

38: end region

40: latch lock

42: structure engaged from rear

44: conduction rail support

46: connection point

48: conduction rail

50: current-carrying element

F: arrow head

Detailed Description

Fig. 1A to 1C show schematic views of a part of a thermal overload protection apparatus 10. This portion includes a switching element 12 for breaking an electrically conductive connection 14 between a current carrying element 16 and a connection point 18 of an electrical component 20 shown in the specific example embodiment of fig. 4-9. This section also includes an actuator mechanism 22 and a trip element 24, the trip element 24 thermally tripping the actuator mechanism 22. In the example shown in fig. 1A-1C, such a trip element 24 is formed as a fusible element 26. This fusible element 26 is a weld joint (solderedconnection) within the conductive connection 14, wherein the weld joint enables current to flow through the connection 16 in the connected state.

Fig. 1A shows the electrically conductive connection 16 with the switching element 12 and the actuator device 22 in an inactive state, in which the switching element 12 cannot be switched or cannot be switched by the actuator device 22, even by tripping of the tripping element 24, without switching the switching element 12, since in this state the actuator device is without force (F = 0N). In this case, the actuator means 22 are formed as elastic elements 28 which function by the clicker principle. Some parts of such a resilient element 28 also serve at the same time as the switching element 12. Thus, the switching element 12 and the actuator means 22 are formed as an integral elastic element 28.

Fig. 2 shows a plan view of such a resilient element 28. The elastic element 28 has three strip-shaped regions 30, 32, 34, which three strip-shaped regions 30, 32, 34 extend parallel to one another and are fixedly interconnected at their respective ends via end regions 36, 38 of the elastic element 28. At least one of the strip-shaped regions 32 is longer than the other two strip-shaped regions 30, 34 (for example, by stamping). The other two strip-shaped regions 30, 34 are for example completely flat, while the longer strip-shaped region (for example the central region) 32 bulges in the preferred direction as a result of the stamping. By pressing the longer strip-shaped regions 32 so that they are recessed in opposite directions, the elastic element 28 can be switched from one state to another state in which the elastic element 28 is recessed in another direction at least in some regions. One state is a force-free state of F =0N, while in the other state the elastic element 28 is biased. Thus, although the illustrated elastic element 28 is not a snap dome, it still has the same principle of operation, i.e. it is considered to be a snap dome principle.

One end region 36 of the elastic element 28 is at the same time also an end region 36 of the switching element 12, so that, in the connected state, the end region 36 is connected to the connection point 18 by means of the fusible element 26 formed in the form of a weld joint. The other end region 38 of the spring element 28 is at the same time also the other end region 38 of the switching element 12, so that the end region 38 is permanently connected to the current-carrying element 16.

Fig. 1B shows the conductive connection 16 of the switching element 12 and the actuator arrangement 22 after switching to a tripped state in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the trip element 24. Fig. 1C shows the open connection 16 after the switching element 12 and the actuator arrangement 22 have switched to a tripped state, in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the tripping element 24, and then by the tripping element 24.

The biased central band region 32 of the elastic element 28 pulls one end region 36 away from the fusible element 26, causing the conductive connection 14 to break.

The portion of the thermal overload protection apparatus shown in fig. 3A-3C corresponds substantially to the overload protection apparatus 10 shown in fig. 1A-1C, and therefore only the differences will be discussed herein.

Fig. 3A shows the electrically conductive connection 16 with the switching element 12 and the actuator device 22 in an inactive state, in which the switching element 12 cannot be switched or cannot be switched by the actuator device 22, even by tripping of the tripping element 24, without the switching element 12 being switched, because in this state the actuator device does not exert any opening force on the switching element 12 (F = 0N). In this case, the trip element 24 is also formed as a fusible element 26.

Fig. 3B shows the conductive connection 16 after the switching element 12 and the actuator arrangement 22 have switched to a tripped state in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the trip element 24. The actuator means 22 is pivoted/bent relative to the switching element 12 under the action of a manually applied force (arrow F) such that the actuator means 22 is mechanically biased by a latch 40 located at the switching element 12 and thus switched to another state. In this embodiment, the actuator device 22 is formed as a "normal" spring element 28 and has a structure 42 for engagement from behind to form a latch 40, which engages from behind one end region of the switching element 12.

Fig. 3C shows the open connection 16 after the switching element 12 and the actuator arrangement 22 have switched to a tripped state, in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the tripping element 24, and then by the tripping element 24 (fig. 3B). The biased resilient element 28 of the actuator arrangement 22 pulls one end region 36 away from the fusible element 26, thereby breaking the conductive connection 14.

Fig. 4 to 6 and 7 to 9 show the overload protection device 10 in a configuration in which the electrical component 20 is mounted on a conductive track support (in particular a Printed Circuit Board (PCB)) 44. In this case, the component 20 is formed as a surface-mountable electronic component which, via its connection points 18, 46 and by means of a reflow soldering method, electrically contacts the conductive tracks 48 of the conductive track support 44.

Fig. 4 to 6 show the following structures: in the described configuration, in the event of a thermal overload, the overload protection device 10 short-circuits the connection points 18, 46 via the switching element 12 formed in the form of a short-circuit bar. The conductive switching element 12 is disposed relative to the assembly 20. The switching element 12 is fastened to the support 44. The end region 36 of the switching element 12 forms an electrical switch together with the current-carrying element 50, the current-carrying element 50 being fastened to the support 44 and being formed as a short-circuit metal.

In this case, fig. 4 shows the overload protection device 10 in an inactive state of the switching element 12 and of the actuator device 22, in which the switching element 12 cannot be switched or cannot be switched by the actuator device 22, even if the tripping element 24 trips, the switching element 12 cannot be switched, because in this state the actuator device does not exert any force on the switching element 12. In this case, the trip element 24 is also formed as a fusible element 26.

Fig. 5 shows the overload protection apparatus 10 after the switching element 12 and the actuator apparatus 22 have switched to the tripped state, in which the actuator apparatus 22, which can be tripped by the tripping element 24, can cause the switching element 12 to switch. The actuator arrangement 22 is mechanically biased against the switching element 12 under a manually applied force, so that the actuator arrangement 22 is mechanically biased and thus switched to the tripped state by a latch (not shown) at the switching element 12. In this embodiment, the actuator means 22 is formed as a resilient element 28.

Fig. 6 shows the assembly 20 being shorted by the switching element 12 formed as a shorting bar after being tripped by the trip element 24. The biased resilient element 28 of the actuator device 22 pulls one end region away from the fusible element 26, thereby forming a short circuit (not shown) via the hook-shaped current carrying element 50 and a suitable conductive track.

Has the following advantages: in the installed state, the overload protection device 10 is force-free. The overload protection can be mounted on the support 44 solely by assembly, in particular by an assembly robot. The welding process does not require fixturing or hold-down. After the mounting/welding process, the device may be activated by interlocking (or creating a depression) of the switching element 12 with the resilient element 28.

In the operating state, the switch formed by the resilient element 28 and the contact point with the fusible element 26 on the support 44 is open. An inadmissible heating of the component 20 above the activation temperature may result in the device 10 being activated in the tripped state. If the activation temperature (melting point of the solder) is exceeded, the tension of the spring element 28 closes the switch formed in this way and thus switches the assembly 20 to the safe state.

Fig. 7 to 9 show the following structures: in the described configuration, the overload protection device 10 breaks the electrically conductive connection 14 between one of the connection points 18 and the current carrying element 16 of the overload protection device 10 in the event of a thermal overload. Such a structure substantially corresponds to the structure described in fig. 3A to 3C.

The conductive switching element 12 is disposed relative to the assembly 20. The switching element 12 is fastened to the support 44. One end region 36 of the switching element 12 forms an electrical switch together with a contact point on the support 44.

Fig. 7 shows the overload protection device 10 in an inactive state of the switching element 12 and the actuator device 22, in which the switching element 12 cannot be switched or cannot be switched by the actuator device 22, even if the tripping element 24 trips, the switching element 12 cannot be switched, since in this state the actuator device does not exert any force on the switching element 12. In this case, the trip element 24 is also formed as a fusible element 26.

Fig. 8 shows the conductive connection 16 of the switching element 12 and the actuator arrangement 22 after switching to a tripped state in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the tripping element 24. The actuator arrangement 22 bends under the manually applied force relative to the switching element 12, so that the actuator arrangement 22 is mechanically biased and thus switched to another state by a latch 40 located at the switching element 12. The actuator device 22 has a structure 42 for latching from behind to form a latch 40, which engages from behind an end region (not shown) of the switching element 12.

Fig. 9 shows the open connection 16 of the switching element 12 and the actuator arrangement 22 after switching to a tripped state, in which the switching element 12 can be switched by the actuator arrangement 22 tripped by the tripping element 24, and subsequently by the tripping element 24. The biased resilient element 28 of the actuator means 22 pulls one end region away from the fusible element 26, thereby breaking the conductive connection 14.

Has the following advantages: in the installed state, the overload protection device 10 is force-free. The overload protection can be mounted on the support 44 solely by assembly, in particular by an assembly robot. The welding process does not require fixturing or pressing. After the mounting/welding process, the device may be activated by interlocking (or creating a depression) of the switching element 12 with the resilient element 28.

In the operating state, the switch formed by the elastic element 28 and the contact point with the fusible element 26 on the support 44 is closed. The unacceptable heating of the assembly 20 above the activation temperature causes the device 10 to be activated in the tripped state. If the activation temperature (melting point of the solder) is exceeded, the tension of the spring element 28 opens the switch formed in this way and thus switches the assembly 20 to the safe state.

Claims (11)

1. A thermal overload protection device (10), characterized in that the thermal overload protection device (10) is adapted to protect an electrical component (20), the thermal overload protection device comprising: a switching element (12) for short-circuiting the connection points (18, 46) of the component (20) or for breaking an electrically conductive connection (14) between at least one of the connection points (18) and a current-carrying element (16) of the overload protection device (10); actuator means (22) for switching the switching element (12) to a suitable short-circuit position or open position; and a trip element (24) to trip the actuator arrangement (22) in a thermally sensitive manner;

wherein the actuator device (22) is switchable to be activated from an inactive state, in which the actuator device (22) is unable to switch the switching element (12), even by tripping the tripping element (24), to a tripped state, in which the actuator device (22) is able to switch the switching element (12);

wherein in the tripped state the actuator arrangement (22) is an actuator arrangement (22) mechanically biased by a latch (40) located at the switching element (12).

2. Overload protection device according to claim 1, characterised in that the trip element (24) is formed as a fusible element (26), which fusible element (26) is tripped by melting.

3. Overload protection device according to claim 1 or 2, characterised in that the actuator means (22) are actuator means (22) as follows: the actuator means (22) can be switched by manually changing the profile of the actuator means (22) or the arrangement of the actuator means (22) relative to the switching element (12).

4. Overload protection device according to claim 1 or 2, characterised in that the actuator means (22) have at least one resilient element (28).

5. Overload protection device according to claim 4, characterised in that the elastic element (28) is a snap dome.

6. Overload protection device according to claim 1 or 2, characterised in that the actuator means (22) is provided with a swelling material and/or a shape memory material and/or a material that changes shape chemically.

7. Overload protection device according to claim 1 or 2, characterised in that the switching element (12) and the actuator means (22) are formed in one piece or comprise at least one common part formed in one piece.

8. Overload protection device according to claim 1 or 2, characterized in that the component (20) is a component (20) which is separable from the overload protection device (10).

9. A component protection device, characterized in that the component protection device comprises a conductive track support (44), at least one component (20) arranged on the conductive track support (44), and an overload protection device (10) according to claim 1 or 2.

10. Component protection device according to claim 9, characterized in that the switching element (12) and/or the actuator device (22) of the overload protection device (10) are supported on the component (20) via the tripping element (24) or via a conducting track (48) of the conducting track support (44), the conducting track support (44) being directly joined to a connection point (18, 46) in the component (20).

11. Component protection device according to claim 9, characterized in that the switching element (12) and/or the actuator means (22) of the overload protection device (10) are directly supported on at least one of the conducting tracks (48) in contact with one of the connection points (18, 46).