EP2702602A1

EP2702602A1 - Overcharge safety device for protecting electrotechnical components from too high operating currents

Info

Publication number: EP2702602A1
Application number: EP12718629.4A
Authority: EP
Inventors: Matthias Kroeker; Roman Dietrich
Original assignee: Tyco Electronics AMP GmbH
Current assignee: TE Connectivity Germany GmbH
Priority date: 2011-04-27
Filing date: 2012-04-24
Publication date: 2014-03-05
Anticipated expiration: 2032-04-24
Also published as: DE102011002294A1; CN103620724A; EP2702602B1; WO2012146573A1; CN103620724B

Abstract

The invention relates to an overload safety device (1) for protecting electrical and/or electronic components from operating currents (lb) which are above a threshold operating current. In order to ensure that the overload safety device (1) prevents operating currents (lb) which are above the threshold operating current in a safe, rapid manner which is substantially independent of external factors, there is provision according to the invention for a switching device (6) of the overload safety device (1) to be able to be actuated by operating currents (lb) which are above the threshold operating current and to be constructed so as to be able to be moved from an operating state (B) into a protection state (S) and for the overload safety device (1) to be constructed with a retention device (11) which has at least one retention magnet (12, 13) which secures the operating state (B).

Description

OVERCHARGE SAFETY DEVICE FOR PROTECTING ELECTROTECHNICAL COMPONENTS FROM TOO HIGH OPERATING CURRENTS

The invention relates to an overload safety device for protecting electrotechnical components from operating currents which are above a threshold operating current, having a switching device which is arranged in an operating state at least partially in an operating current path of the overload safety device and by means of which the operating current path is interrupted in a protection state of the overload safety device.

Overload safety devices are generally known. Fuses are often used which, when reaching the predetermined operating current level, for example, when reaching the threshold operating current, melt and thereby interrupt the operating current path.

However, fuses are slow, with the result that they may not interrupt the operating current path until the operating current is already above the threshold operating current. In particular rapidly increasing operating currents may thus be detected by the fuse only so late that components which are connected in series to the fuse may already have become damaged. Such rapidly changing operating currents may occur, for example, in operating current paths of electrically operated motor vehicles or in motor vehicles with a hybrid drive.

In addition to the rate of the operating current change, other factors, such as, for example, the melting properties of the fuse or the ambient temperatures, may contribute to the operating current being able to be above the threshold operating current. Particularly when motor vehicles are operated, the ambient temperatures may differ greatly and may easily be between -40°C and 85°C. Therefore, temperature differences of up to 100°C or more may occur. At low ambient temperatures, the fuse may be greatly cooled and consequently melt only at inadmissibly high operating currents. At high ambient

temperatures, the fuse may melt even before the threshold operating current is reached so that the fuse interrupts the operating current path even at admissible operating currents. Overload safety devices in the form of fuses must therefore be constructed in such a manner that, at a maximum ambient temperature, the admissible current can still just be permanently conducted. Consequently, at a low temperature, the load of the components to be protected is inadmissibly high in the case of creeping short circuits. - -

An object of the invention is therefore to provide an overload safety device and a method for protecting electrical and/or electronic components which are more suitable than known overload safety devices and which are substantially temperature-independent.

This object is achieved for the overload safety device mentioned in the introduction in that the switching device can be actuated by operating currents above the threshold operating current and is constructed so as to be able to be moved from the operating state into the protection state and the overload safety device is constructed with a retention device which has at least one retention magnet which secures the operating state.

Owing to the direct use of the operating current for determining the operating state or the protection state, control signals and devices which produce them or use them are unnecessary. The securing of the operating state using at least one retention magnet is structurally particularly simple since no other mechanism which is susceptible to

malfunctions is required. The separation or interruption of the operating current path is carried out in a reliable manner and is not dependent on melting properties of the overload safety device used or the ambient temperature. The solution according to the invention may be further improved by means of various configurations which are advantageous per se and which can be freely combined with each other. The configurations and the advantages associated therewith are set out below.

In a first advantageous embodiment, the switching device may be able to be actuated by an operating current magnetic field which is brought about by the operating current flowing through the operating current path when the operating current is above the threshold operating current. The level of the operating current magnetic field brought about by the operating current is directly associated with the operating current without external factors, such as, for example, the ambient temperature, having an influence on the function of the overload safety device.

The switching device may thus be able to be at least partially actuated by the operating current magnetic field brought about by the excessively high operating currents. To this end, a mechanical switching force which moves the switching device in the operating state into the protection state can be produced by the operating current magnetic field. The direct association between the operating current and the magnetic field thereby brought about produces a direct and simple association between the operating current magnetic field and the switching forces which act on the interrupter element. Consequently, the overload safety device may be sized in a particularly simple manner without external factors, such as, for example, the ambient temperature having a significant influence.

So that the switching device can ensure a safe operating state and also a safe protection state, it may be constructed in a bistable manner. Therefore, the retention device may further have in addition to the at least one retention magnet a securing element by means of whose securing forces the switching device is retained in the protection state.

In order to further simplify the mechanical structure of the overload safety device, the securing element may be constructed as a resilient element, which is more powerfully pretensioned in the operating state than in the protection state. The securing force of the resilient element produced as a resilient force can contribute to the switching force or opening force together with the force of the operating current magnetic field. The spring and the contact space located therebelow are sized in such a manner that, owing to contact spacings which can be achieved by the relaxed spring, currents in the kiloampere range at voltages of up to 400 V can be switched off.

In order to be able to integrate the overload safety device in the operating current path in a simple manner, the overload safety device may comprise a portion of the operating current path which brings about the operating current magnetic field. For example, the overload safety device may have an electrical conductor whose ends may form connection elements of the overload safety device. Via the connection elements, the overload safety device may be integrated in the operating current path so that it is connected in series to the components to be protected.

The portion of the operating current path that extends through the overload safety device may comprise an at least partially wound portion which may be formed by the conductor. The wound portion may be constructed in such a manner that it produces the operating current magnetic field which at least partially brings about the switching forces when operating current flows through the conductor. The operating current magnetic field generated by the wound portion may in particular act on the switching device and pull it from an operating position in the direction towards a protection position when the operating current is above the threshold operating current. In the operating position, the switching device may be arranged in the operating state. In the protection state, the switching device may be arranged in the protection position. The protection position may be located downstream of the operating position in an opening direction. The wound portion may be constructed, for example, as a loop or as a coil, which extends in a loop or coil/winding plane. However, with appropriate dimensions of the overload safety device and when the threshold operating current is high enough, it may be sufficient for the wound portion of the conductor to form only one winding or only part of a winding. For example, it may be sufficient for the wound portion to form a half or three- quarter winding and, for example, to be U-shaped and be arranged so as to extend in the winding plane.

The switching device may be formed with a mechanical interrupter element which, in the operating state, can close, for example, a gap in the operating current path or in the electrical conductor of the overload safety device in a bridging manner so that the operating current is able to flow through the interrupter element and the overload safety device. In this operating state, in which the interrupter element is arranged in its operating position, the interrupter element may be retained in its operating position by means of retention forces which are independent of operation and which are produced by the at least one retention magnet. Therefore, the operationally independent retention forces ensure that the operating state of the overload safety device does not readily change. The retention forces may alternatively be resilient forces and the at least one retention magnet may be an electric or a permanent magnet. If the operating current reaches the threshold operating current, the operating current magnetic field reaches a strength which, at least partially and optionally together with the resilient securing force, is sufficient to move the overload safety device out of the operating state. After leaving the operating state, the overload safety device may be in an unstable dynamic state between the operating state and the protection state. In such a dynamic state, the interrupter element may have left the operating state and can change into the protection state. In the protection state, the interrupter element may be arranged in its protection position, the protection position being able to be remote from the operating position in an opening direction. The protection state may also be a stable state which is retained by operationally independent retention forces. The retention forces for ensuring the protection state may also be magnetic or resilient forces. In particular, the retention force for stabilising the protection state may be the resilient force of the securing element. In order to interrupt the operating current path, at least the magnetic retention force has to be overcome. In the operating state, the resilient securing force may be smaller than the magnetic retention force so that the interrupter element is retained in its operating position. If the operating current reaches the threshold operating current, the interrupter element can be moved in the opening direction since the operating current magnetic field brought about by the operating current, optionally in combination with the securing force for securing the protection state that is orientated in an identical manner, brings about greater forces than the magnetic retention force. The switching or opening force can therefore be formed at least partially by the resilient securing force and in particular by a combination of this resilient force with the magnetic force brought about by the operating current magnetic field.

Owing to the movement of the interrupter element in the direction towards the safety position thereof, the operating current path can be interrupted and the operating current may break down. Furthermore, the range of the retention force magnetic field rapidly decreases so that the resilient securing force is sufficient to move the dynamic state of the overload safety device into the protection state.

In order to introduce the retention or securing forces and/or the switching force at least partially brought about by the operating current magnetic field, the switching device may have a coupling device by means of which an opening movement which extends in the opening direction can be forcibly introduced into the interrupter element. To this end, the coupling device may in particular be at least partially connected to the mechanical interrupter element of the switching device arranged in the operating current path in the operating state so as to transmit movement. The forced opening movement ensures that the operating current path is reliably interrupted even when contact elements of the interrupter element become bonded to counter-contact elements of the overload safety device. The coupling device may be constructed with an anchoring element by means of which the interrupter element is force-guided at least in the opening direction. The anchoring element can receive the opening forces and direct them to the interrupter element.

The retention force which secures the operating state can be introduced directly into the anchoring element. For example, the at least one retention magnet can attract the anchoring element in the operating state and thus secure the position thereof in the operating position. In order to ensure the securing of the operating position and to enable the transfer thereof into the protection state, the anchoring element may be arranged closer to the retention magnet in the operating state than in the protection state. In particular in the operating state, the retention magnet may abut the anchoring element so that the retention forces thereof have the maximum effect. In the protection state, the spacing between the at least one retention magnet and the anchoring element may be greater and the effect of the retention magnet on the anchor significantly smaller so that the retention magnet has only a small or even negligible effect on the protection state.

The coupling device may have an actuation element which transmits the opening movement to the anchoring element or introduces it therein. The operating current magnetic field may produce an opening force which acts on the actuation element, is directed in the opening direction and brings about the opening movement. The opening forces which are brought about by the operating current magnetic field may act on the actuation element so that the interrupter element which is connected to the anchoring element so as to transmit movement is subjected to the operating current magnetic field to a lesser extent and therefore can be constructed and operated independently of the interaction with the operating current magnetic field.

The actuation element may have a carrier member, the anchoring element being coupled by the carrier member to the actuation element with force-guiding in the opening direction so as to transmit movement. The carrier member may be constructed as a _η projection or a collar of the actuation element and be arranged upstream of the anchoring element in the opening direction, it being able to at least partially overlap the anchoring element. In the opening direction, therefore, the anchoring element may at least partially cover the actuation element.

In order to be able to pull the anchoring element in the most uniform manner possible in the direction towards the protection position, the actuation element may have at least two carrier members, which each overlap one of at least two ends of the anchoring element that are directed away from each other. The carrier members may be projections which are directed towards each other or carrier lips of the actuation element.

The actuation element may, for example, be constructed in a U-shaped or claw-like manner, an open end of the actuation element being able to be directed away from the wound portion of the conductor. A closed end of the U-shaped or claw-like actuation element may be constructed as a magnetic field absorption plate which is arranged close to the wound portion and which is effectively drawn by the operating current magnetic field in the opening direction.

The open end of the U-shaped or claw-like actuation element may be surrounded or delimited by the carrier member transversely relative to the opening direction, the opening delimited by the carrier member being able to be smaller than the anchoring element transversely relative to the opening direction. The anchoring element is thereby prevented from sliding out of the actuation element counter to the opening direction. The actuation element can first direct the opening force to the anchoring element.

The anchoring element can thus be moved with force-guiding by the actuation element in the opening direction. In order to achieve the stable protection state, however, it may be advantageous for the anchoring element to be retained movably in the opening direction relative to the actuation element. The resilient securing force is thus able to move the anchoring element in the opening direction as soon as the retention force is overcome. The anchoring element can thereby be moved away in the opening direction from the at least one retention magnet which produces the magnetic retention force and into its protection position after the anchoring element has been at least partially moved by the actuation element into the dynamic state.

Since the anchoring element can be moved in the opening direction relative to the actuation element, the spacing between the operating position and the protection position of the anchoring element may be greater than the spacing between the operating position and the protection position of the actuation element. Even small movements of the operating element can thus bring about comparatively large movements of the anchoring element and consequently also the interrupter element. The actuation element may therefore be arranged close in the opening direction to the wound portion or to a magnetic field conductor which conducts the operating current magnetic field so that the operating current magnetic field can effectively interact with the actuation element. The anchoring element can be moved owing to its relatively large movement clearance space in the opening direction sufficiently far out of its operating position for the operating current path to be reliably interrupted and the anchoring element to be able to be moved far enough away from the retention magnet.

Both the retention and securing forces which retain the interrupter element in the operating state and in the protection state may act on the anchoring element. Owing to this simple configuration, it is ensured that the retention or securing forces act on only a single element of the overload safety device, that is to say, on the anchoring element, and can therefore be sized in a simple manner.

The at least one retention magnet and also the resilient element may be supported on the retention device, the retention device being able to be provided in a fixed manner in the overload safety device. Furthermore, the retention device may have a guiding member by means of which the opening force may be guided from the anchor to the interrupter element. The guiding member may comprise, for example, a guiding sleeve which guides a retention shaft or a retention rod. One end of the retention shaft may be fixed to the anchor. Another end of the retention shaft may direct the opening force directed in the opening direction into the interrupter element. For example, the end of the retention shaft or rod directed away from the anchoring element may be arranged in the opening direction upstream of a contact element carrier of the interrupter element and overlap it. If the anchor is moved through the operating current magnetic field in the opening direction, the end of the retention shaft or rod directed away from the anchoring element may abut a side of the contact element carrier directed counter to the opening direction and directly introduce the opening force at that location. Since the contact elements or the counter-contact elements of the interrupter element or the overload safety device may differ from a predetermined ideal geometry, a direct force- guiding of the interrupter element counter to the opening direction may lead to the contact elements not contacting the counter-contact elements in an optimum manner. Consequently, the connection of the retention shaft or rod counter to the opening direction may be constructed in a resilient manner. For example, the retention shaft or rod may be connected to the interrupter element and in particular to the contact element carrier by means of an overtravel spring. Owing to the overtravel spring, the contacts are pressed against the counter-contacts, even if the geometry of the contacts might have changed, for example, owing to erosion. If the contacts are not in abutment against the counter-contacts, for example, in the protection state, the end of the retention shaft or rod directed away from the anchoring element may act as a stop for the interrupter element, against which the overtravel spring presses the contact element carrier. The contact element carrier may thus be pre- positioned at least in the protection state in such a manner that the contacts are arranged correctly with respect to the counter-contacts when the gap of the conductor is closed.

In order to be able to direct the operating current magnetic field into the coupling device and in particular into the actuating element in the most efficient manner possible, the switching device may be constructed with the magnetic field conductor which conducts the magnetic field brought about by the operating current at least partially counter to the opening direction.

The magnetic field conductor may have a core element around which the wound portion of the operating current path or the electrical conductor is at least partially wound. The core element may conduct the magnetic field counter to the opening direction more effectively than, for example, air. For example, the core element may be T-shaped and may be arranged substantially along a central axis of the wound portion that may extend parallel with the opening direction. Portions of the core element which extend away from a portion of the core element extending in the opening direction may form a magnetic field discharge plate transversely relative to the opening direction. The magnetic field discharge plate and the magnetic field absorption plate of the actuation element may be arranged so as to be spaced so far apart from each other in the operating state and in the opening direction that operating current magnetic field forces acting on the actuation element in combination with the resilient securing forces are greater when the threshold operating current is reached than the magnetic retention force which acts on the anchoring element in the operating state, that is to say, by adjusting the spacing of the magnetic field discharge plate 28 and the actuation element 19, the threshold current can be preset. Furthermore, the spacing between the plates may be so large that the actuation element, at the latest when the core element is reached, has removed the anchoring element so far from the retention magnets that the magnetic retention forces thereof acting on the anchoring element are smaller than the resilient forces of the resilient element alone. In order to further improve the efficiency of the introduction of the operating current magnetic field into the actuation element, the magnetic field conductor may have at least one magnetic field short-circuit element which extends parallel with the core and transversely relative to the opening direction. The at least one magnetic field short-circuit element may receive the magnetic field of the actuation element and direct it back to the core element, whereby a magnetic circuit is substantially closed and is interrupted in the operating state only by the spacing between the core element and the actuation element. The magnetic field short-circuit element may extend in particular so far counter to the opening direction that it is arranged in the opening direction at least partially beside the actuation element. Not only does it thereby direct the magnetic field effectively back to the core element but rather it may further also protect the actuation element against undesirable rotation about the opening direction, whereby the position of the interrupter element can also be protected against undesirable rotations. The magnetic field short-circuit element may also abut the actuation element. The magnetic field conductor may be constructed symmetrically and with two magnetic field short-circuit elements. The magnetic field brought about by the operating current in the wound portion may thereby be conducted more effectively and furthermore the movement of the actuation element may be guided more precisely in the opening direction. - -

The invention is explained below by way of example with reference to embodiments and the drawings. The various features of the embodiments may be combined independently of each other, as already set out in the individual advantageous configurations. In the drawings:

Figure 1 is a schematic illustration of an embodiment of the overload safety device according to the invention in an operating state;

Figure 2 is a schematic illustration of the overload safety device of the embodiment of Figure 1 in a protection state.

The structure and function of an overload safety device according to the invention are first described with reference to the embodiment of Figure 1.

Figure 1 is a schematic, perspective front view of the overload safety device 1. The overload safety device 1 comprises two connection elements 2, 3 by means of which the overload safety device 1 can be integrated in an operating current path of an operating current circuit, for example, of a motor vehicle. An electrical conductor 4 of the overload safety device 1 can connect the connection elements 2, 3 to each other. The electrical conductor 4 can be integrated in the operating current path and the overload safety device 1 can be connected in series to electrical and/or electronic components of the operating current path. The electrical conductor 4 may therefore be a portion 5 of the operating current path arranged in the overload safety device 1, when the overload safety device 1 is incorporated therein. The overload safety device 1 may have a switching device 6 which electrically constantly closes the portion of the operating current path 5 in an operating state B of the overload safety device 1.

According to the illustrated embodiment, the switching device 6 may have a mechanical interrupter element 7 which may be constructed as a contact bridge. The mechanical interrupter element 7 may bridge a gap L in the portion of the operating current path 5 in the operating state B. Contact elements 8, 9 may be arranged at ends of a contact element carrier 10 of the switching device 6, the contact element carrier 10 electrically connecting the contact elements 8, 9 to each other. The overload safety device 1 may have counter-contact elements 8', 9' for the contact elements 8, 9, the contact elements 8, 9 being able to be electrically connected to the counter-contact elements 8', 9' in the operating state B. In order to close the gap L, the mechanical interrupter element 7 may be arranged in its operating position Pb so that the contact elements 8, 9 can be connected to the counter- contact elements 8', 9' and may abut each other in pairs.

In order to retain the interrupter element 7 in the operating position Pb, the overload safety device 1 may be provided with a retention element 11. The retention device 11 may bring about retention forces which are operationally independent in order to retain the interrupter element 7 in the operating state B in its operating position Pb. These

operationally independent retention forces may be magnetic or resilient forces. According to the illustrated embodiment of Figure 1, the retention device 11 may comprise at least one and in particular two retention magnets 12, 13 which secure the operating position Pb of the interrupter element 7. The retention device 11 and the electrical conductor 4 may be arranged in a fixed manner in the overload safety device 1.

The retention magnets 12, 13 may interact with an anchoring element 14 and in particular retain the anchoring element 14 in a magnetic manner. The anchoring element 14 may be connected to the interrupter element 7 so as to transmit movement so that the magnetic retention of the anchoring element 14 by the retention magnets 12, 13 can ensure that the interrupter element 7 is fixed in the operating position Pb. In the illustrated view of the overload safety device 1, the retention magnets 12, 13 are covered by the anchoring element 14.

When viewed from the gap L, there is arranged behind the anchoring element 14 a wound portion 15 of the electrical conductor 4. A winding plane P of the portion 15 may be arranged parallel with the anchoring element 14 or the gap L. If an operating current lb flows from the connection element 2 to the connection element 3, or vice-versa, the wound portion 15 may produce a magnetic field by means of which forces are introduced into the interrupter element 7. These operating current magnetic field forces or opening forces may seek to move the interrupter element 7 from its operating position Pb in an opening direction R. If the forces produced by the magnetic field at least partially exceed the retention forces of the retention magnets 12, 13, the anchoring element 14 can be moved away from the retention magnets 12, 13 and the gap L in the opening direction R towards the wound portion 15. The anchoring element 14 may consequently be connected to the interrupter element 7 in such a manner that such an opening movement of the anchoring element 14 is forcibly transmitted to the interrupter element 7 and the interrupter element 7 follows this opening movement.

However, as soon as the portion of the operating current path 5 which extends through the overload safety device 1 is interrupted, the operating current magnetic field which is brought about by the wound portion 15 can break down. If the anchoring element 14 is then still so close to the retention magnets 12, 13 that the magnetic forces thereof retract the anchoring element 14, the portion of the operating current path 5 can be immediately closed again. This may lead to an undesirable operating mode, in which the overload safety device 1 opens and closes the operating current path in rapid succession.

In order to prevent such an operating mode, the retention device 11 may have a securing element E, for example, an opening force storage device, whose securing force is at least partially released as soon as the interrupter element 7 is moved out of its operating position Pb in the opening direction R. For example, the securing element E may have a resilient element 16 which in the operating state B presses in the opening direction R against the anchoring element 14 but whose resilient force in the operating state B is not sufficient alone to release the anchoring element 14 from the retention magnets 12, 13.

As soon as the operating current magnetic field of the wound portion 15 releases the anchoring element 14 from the retention magnets 12, 13, the magnetic retention force of the retention magnets 12, 13 on the anchoring element 14 rapidly decreases and the resilient force of the resilient element 16 may be greater in such a dynamic state of the overload safety device 1 than the retention force of the retention magnets 12, 13. Consequently, the resilient element 16 can move the anchoring element 14 and consequently the interrupter element 7 in the opening direction R towards the wound portion 15 of the electrical conductor 4 as soon as the gap L is no longer bridged by the switching device 6. The interrupter element 7 also follows such an opening movement of the anchoring element 14 brought about by the resilient element 16. This opening movement prevents the undesired operating mode.

The anchoring element 14 may be part of a coupling device 18 of the overload safety device 1. The coupling device 18 may in addition to the anchoring element 14 also have an actuation element 19. The actuation element 19 may be substantially U-shaped, the open side of the actuation element 19 being able to be directed away from the wound portion 15 and counter to the opening direction R towards the gap L. The actuation element 19 may have at least one carrier member M which may be constructed in such a manner that it at least partially overlaps the anchoring element 14 at the side thereof facing the gap L. To this end, the actuation element 19 may, for example, be constructed in a claw-like or clamp-like manner, free ends 22, 23 of members 20, 21 of the substantially U-shaped actuation element 19 being able to be directed towards each other as carrier members M. In particular those ends 22, 23 which are directed towards each other may overlap opposing portions or ends W of the anchoring element 14 and at least in the operating state B be in abutment with a side 24 of the anchoring element 14 directed towards the gap L and counter to the opening direction R. The carrier members M or the ends 22, 23 may be constructed as a continuous collar or mutually opposing carrier lips which protrude inside the actuation element 19 and delimit the opening O of the actuation element 19 in such a manner that the opening O transversely relative to the opening direction R is smaller than the anchoring element 14. In the opening direction R downstream of the opening O, the actuation element 19 may become wider, optionally even abruptly, whereby an undercut which forms the carrier member M may be formed. A lower closed portion of the substantially U-shaped actuation element 19 may be constructed as a magnetic field absorption plate 25. The magnetic field absorption plate 25 may extend so as to be orientated transversely relative to the opening direction R and be arranged between the anchoring element 14 and the wound portion 15. Owing to the fact that the magnetic field absorption plate 25 is arranged closer to the wound portion 15 than the anchoring element 14, the operating current magnetic field of the wound portion 15 may bring about greater forces on the magnetic field absorption plate 25 than on the anchoring element 14. A spacing A between the core element 26 and the magnetic field absorption plate 25 may be of such a size in the opening direction R that the operating current magnetic field produced by the operating current lb of the wound portion 15 is sufficiently strong to disengage the anchoring element 14 from the retention magnets 12, 13 so far that the resilient force of the resilient element 16 in the dynamic state is sufficient to move the anchoring element 14 in the opening direction R further from the retention magnets 12, 13.

Without the actuation element 19, the spacing between the wound portion 15 and the anchoring element 14 could be reduced in order to increase the forces of the operating current magnetic field directly on the anchoring element 14. If the spacing between the anchoring element 14 and the wound portion 15 is too small, however, the opening movement brought about by the resilient element 16 may be too small to move the anchoring element 14 far enough away from the retention magnets 12, 13.

A clearance H directed in the opening direction R between the magnetic field absorption plate 25 and the mutually facing end portions 22, 23 or the carrier member M of the actuation element 19 may be sized in such a manner that the anchoring plate 14 is arranged far enough away from the retention magnets 12, 13 at least when it is pressed by the resilient element 16 against the magnetic field absorption plate 25.

So that the operating current magnetic field can effectively be introduced into the actuation element 19, the switching device 6 may comprise a magnetic field conductor 26. The magnetic field conductor 26 may be fixedly arranged in the overload safety device 1 and be constructed in such a manner that it receives the operating current magnetic field produced by the wound portion 15 and the operating current lb and conducts it towards the actuation element 19. The magnetic field conductor 26 may be constructed with a core element 27, the wound portion 15 being able to at least partially extend around the core element 27. The wound portion 15 may be constructed, for example, as a 3/4 winding in whose centre the core element 27 which extends in the opening direction R may be arranged. The core element 27 may be substantially T-shaped, an end of the core element 27 facing the actuation element 19 being able to be constructed substantially as a magnetic field discharge plate 28, which directs the operating current magnetic field effectively in the direction towards the actuation element 19. The core element 27 may protrude beyond the wound portion 15 of the electrical conductor 4 counter to the opening direction R so that the actuation element 19 only strikes the core element 27 during opening movements in the opening direction R and consequently contact of the actuation element 25 with the electrical conductor 4 and in particular with the wound portion 15 thereof is prevented.

The magnetic field conductor 26 may have at least one magnetic field short— circuit element 29 which extends parallel with the core element 26 and counter to the opening direction R. The magnetic field short-circuit element 29 may receive the operating current magnetic field introduced into the actuation element 19 and conduct it back to the core element 27 so that a substantially closed magnetic circuit is produced, by means of which the efficiency of the switching device 6 is increased.

The magnetic field conductor 26 may be constructed in a symmetrical and in particular W- shaped manner, the magnetic field conductor 26 being able to have two magnetic field short-circuit elements 29, 30 which may flank the core element 27 counter to the opening direction R.

In addition to increasing the efficiency of the switching device 6, the magnetic field short-circuit elements 29, 30 may act as guides for the opening movement of the actuation element 19. Rotations of the actuation element 19 and consequently also the interrupter element 7 about the opening direction R can thereby effectively be prevented.

In order to transmit movement, the anchoring element 14 may be connected to the interrupter element 7 in a substantially rigid manner. For example, the anchoring element 14 and the interrupter element 7 or the contact element carrier 10 thereof may be connected to each other by means of a retention rod or shaft 31. The anchoring element 14 may be fixed to the retention rod 31 and consequently transmit the opening movement directly to the retention rod 31. An end 32 of the retention rod 31 directed away from the anchoring element 14 can thus be connected to the interrupter element 7 and in particular to the contact element carrier 10 thereof in such a manner that the retention rod 31 forcibly transmits the opening movement in the opening direction R to the interrupter element 7. For example, the retention rod 31 may extend through an opening 33 in the contact element carrier 10 which extends in the opening direction R, the diameter of the end 32 being able to be greater than the diameter of the opening 33.

In order to retain the interrupter element 7 in the operating position Pb, the retention rod 31 can also be connected counter to the opening direction R to the interrupter element 7 so as to transmit movement. However, in the case of a completely rigid connection between the retention rod 31 and the interrupter element 7, problems may arise if the geometry of the contact elements 8, 9 or the counter-contact elements 8', 9' differs from a desired geometry. For example, both the contact elements 8, 9 and the counter-contact elements 8', 9' may become so deformed during operation owing to erosion that the contact elements 8, 9 and the counter-contact elements 8', 9' are no longer correctly contacted in the case of a rigid connection of the interrupter element 7 with respect to the retention rod 31.

In order to prevent such problems, the retention rod 31 may be connected to the interrupter element 7 counter to the opening direction R so as to resiliently transmit movement.

For example, there may be fixed to the retention rod 31 a resilient element 34 which can be connected to the contact element carrier 10 so as to transmit resilient force.

According to the embodiment of Figure 1, the retention rod 31 may be connected to the contact element carrier 10 by means of the resilient element 34 which is constructed in this instance as an overtravel spring. The resilient element 34 may be constructed in a symmetrical manner, ends 35, 36 of the optionally leaf- spring-like resilient element 34 being able to be secured to portions of the contact element carrier 10 which face the contact elements 8, 9 in an opening direction R. A central portion 37 of the resilient element 34 may be fixed to the retention rod 31.

In order to be able to guide movements parallel with the opening direction R of the retention rod 31 and consequently also the interrupter element 7, the retention device 11 may comprise a guiding member 38. The guiding member 38 may be formed with a guiding sleeve 39, the guiding sleeve 39 being able to extend in the opening direction R and being able to guide movements of the retention rod 31 parallel with the opening direction R. For example, the retention shaft or rod 31 may be guided through the guiding sleeve 39, the guiding sleeve 39 being able to be arranged in a fixed manner in the overload safety device 1.

Figure 2 is a schematic, perspective front view of the embodiment of Figure 1, the overload safety device 1 being illustrated in a protection state S.

In the protection state S of the overload safety device 1 illustrated in Figure 2, the gap L is no longer bridged by the interrupter element 7. Instead, the interrupter element 7 is illustrated in a state arranged in the protection position Ps thereof, the protection position Ps being arranged in the opening direction R downstream of the operating position Pb of the interrupter element 7.

The actuation element 19 in the illustrated protection state S of the overload safety device 1, may be in abutment, for example, with the magnetic field absorption plate 25 thereof, against the core element 27 and in particular the magnetic field discharge plate 28 thereof. Even when no operating current lb is flowing through the electrical conductor 4 in the protection state S and therefore the wound portion 15 cannot produce an operating current magnetic field, the actuation element 19 may nonetheless securely abut the core element 27. The actuation element 19 may be pressed by the anchoring element 14 in the opening direction R against the core element 27 since the anchoring element 14 is pressed by the resilient element 16 in the opening direction R. The interrupter element 7 may also be securely retained by the resilient element 16 in the protection position Ps by means of the anchoring element 14 and the retention rod 31. The overload safety device 1 and in particular the switching device 6 thereof may thus be constructed in a bistable manner, one stable state being able to be the operating state B and another stable state the protection state S. The dynamic state may be an unstable transitional state. The retention magnets 12, 13 may secure the stable operating state B during normal operation. If an inadmissible operating current lb which is above the threshold operating current actuates the switching device 6, the overload safety device 1 may leave the stable operating state B and move via the unstable dynamic state into the stable protection state S which can be secured by the resilient element 16 in a stable manner.

Claims

1. Overload safety device (1) for protecting electrotechnical components from operating currents (lb) which are above a threshold operating current, having a switching device (6) which is arranged in an operating state (B) at least partially in an operating current path (5) of the overload safety device (1) and by means of which the operating current path (5) is interrupted in a protection state (S) of the overload safety device (1), characterised in that the switching device (6) can be actuated by operating currents (lb) above the threshold operating current and is constructed so as to be able to be moved from the operating state (B) into the protection state (S) and the overload safety device (1) is constructed with a retention device (11) which has at least one retention magnet (12, 13) which secures the operating state (B).

2. Overload safety device (1) according to claim 1, characterised in that the overload safety device (1) is constructed in a bistable manner.

3. Overload safety device (1) according to claim 1 or 2, characterised in that the retention device (11) has a securing element (E) by means of which the switching device (6) is retained in the protection state (S).

4. Overload safety device (1) according to claim 3, characterised in that the securing element (E) is constructed as a resilient element (16), which is more powerfully pretensioned in the operating state (B) than in the protection state (S).

5. Overload safety device (1) according to any one of claims 1 to 4, characterised in that the switching device (6) has a coupling device (18) which is connected to a mechanical interrupter element (7) of the switching device (6) arranged in the operating current path (5) in the operating state (B) so as to transmit movement.

6. Overload safety device (1) according to claim 5, characterised in that the coupling device (18) is constructed with an anchoring element (14) by means of which the interrupter element (7) can be moved with force-guiding at least in an opening direction (R).

7. Overload safety device (1) according to claim 6, characterised in that the anchoring element (14) is arranged closer to the retention magnet (12, 13) in the operating state (B) than in the protection state (S).

8. Overload safety device (1) according to claim 6 or 7, characterised in that the coupling device (18) has an actuation element (19) having a carrier member (M), the anchoring element (14) being coupled to the actuation element (19) by the carrier member (M) with force-guiding in the opening direction (R).

9. Overload safety device (1) according to claim 8, characterised in that the carrier member (M) is arranged upstream of the anchoring element (14) in the opening direction (R) and overlaps it.

10. Overload safety device (1) according to claim 8 or claim 9, characterised in that the actuation element (19) has two carrier members (M) which overlap ends (W) of the anchoring element (14) that are directed away from each other.

11. Overload safety device (1) according to any one of claims 8 to 10, characterised in that the anchoring element (14) is retained movably in the opening direction (R) relative to the actuation element (19).

12. Overload safety device (1) according to any one of claims 8 to 11, characterised in that the spacing between an operating position (Pb) and a protection position (Ps) of the anchoring element (14) is greater than the spacing between an operating position (Pb) and a protection position (Ps) of the actuation element (19).

13. Overload safety device (1) according to any one of claims 1 to 12, characterised in that the overload safety device (1) comprises an at least partially wound portion (15) of the operating current path (5).

14. Overload safety device (1) according to claim 13, characterised in that the actuation element (19) is orientated parallel with a loop plane (P) formed by the wound portion (15) of the operating current path (5).