SWITCHING DEVICE HAVING A STOPPER AND METHOD FOR ACTIVATING A SWITCHING DEVICE - Patent application

Abstract

Switching device with stopper and method of operating the switching device. The switching device (10) includes first and second stationary contacts (55, 56), a contact bridge (40), first and second movable contacts (45, 46) arranged on the contact bridge (40), a contact spring (31), a contact bridge carrier (30), a housing (35), and at least one stopper (71, 72). The contact bridge carrier (30) is movable and coupled to the contact bridge (40) via the contact spring (31). The at least one stopper (71, 72) is connected to the housing (35) and configured to limit the movement of the contact bridge (40) in the event of a short circuit. The switching device (10) also includes a magnetic drive assembly having an electric coil (48), a magnetic core (50), and an armature (47), the armature (47) being movable and connected to the contact bridge carrier (30).

Description

[Technical field]

[0001] The present disclosure relates to a switching device having a stopper and a method of operating the switching device. [Background technology]

[0002] The switching device is realized as an electromechanical switching device, in particular for high power battery networks in the field of electrical mobility, for example for conducting and switching bidirectional DC currents. The switching device is also configured for safe disconnection in the event of a short circuit.

[0003] In short circuit switching of a protection switching device, strong dynamic forces react on the contact system due to the high current. The resulting strong opening impulse can lead to rebound and re-contact of the contact system. Re-closure of the contacts can lead to a different problem: due to re-closure, the device does not achieve galvanic isolation. Re-closure of the contacts can lead to recurring bouncing, because when the contacts are closed, the short circuit current can flow again. This can lead to a re-occurrence of the first problem. Due to re-closure, the extinguishing time and stresses on the switching device are increased.

[0004] US Pat. No. 5,399,633 describes a switching device for carrying and disconnecting bidirectional DC current. Summary of the Invention [Problem to be solved by the invention]

[0005] It is an object of the present invention to provide a switching device and a method of operating a switching device which reduces the likelihood of unintentional re-contacting of the switching contacts. [Means for solving the problem]

[0006] These objects are achieved by the subject matter of the independent claims. Further developments and embodiments are set out in the dependent claims.

[0007] A switching device is provided that includes a magnetic drive assembly having first and second fixed contacts, a contact bridge, first and second movable contacts disposed on the contact bridge, a contact spring, a contact bridge carrier, an electric coil, a magnetic core, and an armature, a housing, and at least one stopper. The contact bridge carrier is movable and coupled to the contact bridge via the contact spring. The armature is movable and connected to the contact bridge carrier. The at least one stopper is connected to the housing and configured to limit movement of the contact bridge in the event of a short circuit.

[0008] Advantageously, the at least one stopper obtains the function of a brake or limiter of the movement of the contact bridge in the event of a short circuit. By reducing the kinetic energy of the contact bridge during forced contact bridge opening induced by a high-energy short circuit arc, the probability of reconnection is reduced.

[0009] In one embodiment, the switching device is configured such that a short-circuit current flows through the first fixed contact, the first movable contact, the contact bridge, the second movable contact and the second fixed contact in the event of a short circuit, and movement of the contact bridge carrier causes movement of the contact bridge from its on position in a switched-on state of the switching device to at least one stopper.

[0010] In one embodiment of the switching device, the maximum clearing distance is the maximum distance of movement of the contact bridge from its on position in the switched-on state of the switching device to at least one stop in case of a short circuit. If the maximum clearing distance is too small, the risk of arc sticking increases. If the maximum clearing distance is too large, the risk of re-contact increases.

[0011] In one embodiment of the switching device, the at least one stopper and the part of the housing connected to the at least one stopper are made of the same material, for example, the at least one stopper is made from a polymer, for example, the at least one stopper and the part of the housing connected to the at least one stopper are manufactured by injection molding.

[0012] In one embodiment of the switching device, the at least one stopper is made from a first material and a portion of the housing connected to the at least one stopper is made from a second material. The at least one stopper is attached to the housing.

[0013] In one embodiment of the switching device, the contact bridge carrier and the contact bridge are configured such that the relative movement of the contact bridge with respect to the contact bridge carrier from its on position in the switched-on state of the switching device is limited to an end stop distance in the event of a short circuit. If the end stop distance is too small, arc attachment or double connection may occur.

[0014] In an embodiment of the switching device, the relative movement of the contact bridge from its on position in the switched-on state of the switching device relative to the contact bridge carrier is limited by a block length of at least one bumper and / or a contact spring connected to the contact bridge carrier. The block length is the length of the contact spring with its coils directly adjacent to one another. In other words, the contact spring can only be compressed up to its block length.

[0015] In one embodiment of the switching device, the end stop distance depends on the maximum clear distance.

[0016] In one embodiment of the switching device, the end stop distance has a value F according to the following formula:

number

[0017] In one example, the maximum clear distance is in the range of 6.3mm to 8.6mm, and therefore the end stop distance is in the range of 4.8mm to 6.8mm.

[0018] In one embodiment of the switching device, the clearing distance is the distance of travel of the contact bridge from its ON position in the switched-on state of the switching device to its OFF position in the switched-off state of the switching device in the absence of a short circuit. If the clearing distance is too short there is a risk of arcing and re-contact.

[0019] In one embodiment of the switching device, the maximum clear distance is greater than the clear distance. In one embodiment, the maximum clear distance depends on the clear distance.

[0020] In one embodiment of the switching device, the maximum clearing distance has a value E according to the following formula:

number

[0021] For example, the clear distance is in the range between 5.1 mm and 6.6 mm.

[0022] In an embodiment of the switching device, the contact bridge carrier comprises a limiter, the limiter being configured to limit movement of the contact bridge inside the contact bridge carrier towards the first and second fixed contacts.

[0023] In one embodiment of the switching device, the switching device includes a return spring. One side of the return spring contacts the housing. The other side of the return spring is coupled to the contact bridge carrier. The switching device includes, for example, a part connecting the other side of the spring to the contact bridge carrier. The part or parts provide a force from the return spring on the contact bridge carrier. The return spring is configured to provide a force on the contact bridge carrier in a direction away from the first and second fixed contacts.

[0024] In one embodiment, the switching device includes a magnetic drive assembly having an electric coil, a magnetic core and an armature, the armature being movable, the armature being connected to or directly attached to the contact bridge carrier.

[0025] In one embodiment, the switching device is configured such that the movement of the contact bridge relative to the contact bridge carrier in the event of a short circuit begins before the armature starts to move.

[0026] In one embodiment of the switching device, the housing is configured to limit the movement of the armature. The contact bridge provides a force to the armature via the contact spring and the contact bridge carrier. In case of a short circuit, a current sensor of the switching device detects that the load current exceeds a predefined limit, indicating a short circuit. The load current exceeding the predefined limit can be referred to as a short circuit current or an overload current. The current sensor triggers that the electric coil is rapidly de-energized, resulting in the movement of the armature. The movement of the armature and the above-mentioned force are in the same direction. The movement of the armature is limited by the housing. The kinetic energy of the armature is reduced by the armature hitting the housing.

[0027] In one embodiment of the switching device, the contact bridge comprises: - In case of a short circuit, - during the transition of the switching device from the switched-off state to the switched-on state, and - When the switching device transitions from the switched-on state to the switched-off state, It is configured to perform linear motion.

[0028] In one embodiment, the switching device includes a first terminal contact to which the first fixed contact is attached and a second terminal contact to which the second fixed contact is attached, both of the first and second terminal contacts being bent into a U-form or U-shape.

[0029] A method is provided for operating a switching device, the switching device including first and second fixed contacts, a contact bridge, first and second movable contacts disposed on the contact bridge, a contact spring, a contact bridge carrier that is movable and coupled to the contact bridge via the contact spring, a housing, at least one stopper connected to the housing, and a magnetic drive assembly having an electric coil, a magnetic core and an armature, the armature being movable and connected to the contact bridge carrier. The method includes limiting movement of the contact bridge by the at least one stopper in the event of a short circuit.

[0030] Advantageously, the switching device implements a mechanical system that minimizes contact rebound in the short-circuit switching device.The DC switching device obtains improved short-circuit switching behavior due to at least one mechanical stop.

[0031] The method for operating a switching device may for example be implemented by a switching device according to one of the embodiments defined above, and thus configurations disclosed with respect to the method can be used with respect to the switching device and vice versa.

[0032] In one example, the switching device is implemented as a DC switching device with improved short circuit switching behavior due to mechanical end stops. The mechanical system uses mechanical end stops at predetermined distances to minimize contact rebound in the short circuit switching device and reduce energy, thus preventing the contact system from re-contacting. To minimize rebound, the kinetic energy in the contact system is reduced. A solution to minimize this energy is, for example, optimizing at least one of the following parameters: distance before reaching the end stop, clear distance, maximum clear distance, over-travel and travel of the magnetic actuator. The ideal adjustment of these values ​​results in a fast and uniform arc run and no re-contact in the event of high short circuit current.

[0033] In one example, a DC switching device is implemented to switch load and overload currents, in particular short circuit currents, and prevents re-contact of the switching device, which may occur due to high dynamics after short circuit disconnection.

[0034] In one example, the structure of the switching device is similar to that of a conventional contactor. The switching device includes an electromagnetic drive and a contact / quench system. Unlike a contactor, the contact / quench system, in combination with a special tripping mechanism, can also handle very high short circuit currents.

[0035] In one embodiment, the contact device is rigidly coupled to the armature of the electromagnetic drive. Due to the resulting arc after electrodynamic lift-off in the short circuit case and the resulting pressure build-up in the switching chamber, the armature movement in the "off" direction is significantly faster than when the load current is switched off. The larger acceleration of the armature can make the armature with the rigidly coupled contact device bounce strongly towards "on" after reaching the end position where the fixed and movable contacts re-contact, thereby allowing the short circuit current to flow again.

[0036] In one example, re-contact / re-bounce can be prevented by, for example, adjusting at least one of the idle stroke of the contact system, the maximum clear distance in case of overload, and the maximum free travel of the movable contact parts.

[0037] In the event of a short circuit, the movable contact parts can in principle be opened by two mechanisms: the first is electrodynamic lift-off due to high Holm forces, which in the case of a short circuit current exceed the contact pressure caused by the compressed contact pressure spring. In the case of switching devices, the Holm forces act directly on the contacts. The current direction in the contacts results in an antiparallel current direction, which in turn results in a lift-off force (microscopic). The contacts open even though the electromagnetic actuator is still closed. The limit can be set by a stop in the contact bridge carrier or by the blocking length of the contact spring. The maximum contact opening distance caused by electrodynamic lift-off is referred to below as the end stop distance or maximum free travel of the movable contact bridge.

[0038] The second is the opening movement initiated by the armature and the rigidly connected contact arrangement. Rapid de-energization of the electric coil of the electromagnetic actuator occurs after an overload current is detected. As a result, the armature with the rigidly connected contact arrangement is moved towards the OFF position by the contact spring and the impression spring, opening the contacts at the beginning of the idle stroke.

[0039] In the case of normal load, the contact opening occurs only via the de-energization of the driving electric coil. In the case of overload, a combination of the two mechanisms occurs, whereby, due to the low inertial mass, the electrodynamic lift-off occurs more quickly in terms of time. Both mechanisms are independent of each other. The theoretically achievable contact opening distance is thus the sum of the maximum free flight distance and the empty stroke. A large contact opening distance helps the arc to leave the contact quickly, but the probability of re-contact increases due to the highly preloaded contact spring. It is therefore advantageous to limit the maximum clearing distance to a reasonable value, so as not to inhibit the arc travel, but the contact spring is already relaxed again. In this case, the moving contact bridge reaches its stop before the armature reaches its end stop. This task is constructively solved by a stopper in the switching chamber for the moving contact bridge.

[0040] In one example, the parameters end stop distance (also called maximum free travel), clear distance (also called idle stroke or free stroke), and maximum clear distance can be selected in such a way that the following functions are ideally resolved: uniform arc travel at high speeds, no recontact at high short circuit currents, and minimum pull power of the electromagnetic drive. In this example, outside these ranges, arc travel may be prevented or mechanical recontact may occur when too large a short circuit current is interrupted.

[0041] In one example, the switching device is implemented as an electromechanical switching device for conducting and switching bidirectional DC current, particularly for high power battery networks in the field of electro-mobility.

[0042] The switching device is, for example, part of an electric and / or hybrid vehicle. The switching device is, for example, realized as a contactor and / or a circuit breaker. The switching device is, for example, implemented as an in-air switch or as a hermetically sealed switching device.

[0043] The following description of the figures of the embodiment may further illustrate and explain aspects of the switching device. Parts and devices having the same structure and the same effect respectively appear with the same reference symbols. Insofar as the parts or devices correspond to each other with respect to their functions in the different figures, the description will not be repeated for each of the following figures. [Brief description of the drawings]

[0044] [Figure 1] 1 illustrates an example of a switching device in different states or phases. [Diagram 2] 1 illustrates an example of a switching device in different states or phases. [Diagram 3] 1 illustrates an example of a switching device in different states or phases. [Figure 4] 1 illustrates an example of a switching device in different states or phases. [Figure 5A] 1 shows a detail of an example of a contact area of ​​a switching device. [Figure 5B] 1 shows further details of an example of a switching device. [Figure 5C] 1 shows further details of an example of a switching device. [Figure 6A] 1 illustrates characteristics of different examples of switching devices. [Figure 6B] 1 illustrates characteristics of different examples of switching devices. [Figure 6C] 1 illustrates characteristics of different examples of switching devices. [Figure 7] 4 shows example values ​​of parameters of a switching device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] FIG. 1 shows an example of a switching device 10. The switching device 10 includes a first movable contact 45, a second movable contact 46, a first fixed contact 55, a second fixed contact 56, and a contact bridge 40. The contact bridge 40 is realized as a cuboid. The contact bridge 40 is made of, for example, copper. The contact bridge 40 may be called a switching bridge or a switching contact bridge. The first and second movable contacts 45, 46 are fixed to the contact bridge 40. The first and second movable contacts 45, 46 are made of a metal, for example, a silver oxide material. The thickness of the first and second movable contacts 45, 46 is, for example, in the range of 0.5 mm to 1.5 mm (0.5 mm is equal to 500 μm, and 1.5 mm is equal to 1500 μm).

[0046] The switching device 10 includes a first terminal contact 51 and a second terminal contact 52. The first fixed contact 55 is fixed to the first terminal contact 51. The second fixed contact 56 is fixed to the second terminal contact 52. The first and second fixed contacts 55, 56 are made of metal, for example, silver oxide material. The thickness of the first and second fixed contacts 55, 56 is, for example, in the range of 0.5 mm to 1.5 mm. The first and second terminal contacts 51, 52 have a bent form. The first and second terminal contacts 51, 52 have a U-shape. The first and second terminal contacts 51, 52 are, for example, copper-free.

[0047] The switching device 10 comprises a contact bridge carrier 30. The contact bridge carrier 30 consists, for example, of a plastic. The contact bridge carrier 30 consists, for example, of a polymer, such as a thermoplastic or thermosetting material. The material of the contact bridge carrier 30 has, for example, high dimensional and temperature stability as well as an electrical resistance to electric currents at its surface. The contact bridge 40 is inserted into the contact bridge carrier 30. In FIG. 1 the contact bridge 40 is partially "behind" the contact bridge carrier 30. The switching device 10 comprises a contact spring 31, which can be referred to as a contact pressure spring. The contact spring 31 connects the contact bridge 40 to the contact bridge carrier 30. The contact spring 31 is, for example, realized as a compression spring or a tension / compression spring.

[0048] Furthermore, the contact bridge carrier 30 comprises a barrier 32 arranged in the space between the first terminal contact 51 and the second terminal contact 52. The barrier 32 is arranged in an isolated manner between the first terminal contact 51 and the second terminal contact 52. The barrier 32 is free from contact with the first and second terminal contacts 51, 52. The barrier 32 has the form of a plate. The barrier 32 and the contact bridge carrier 30 are, for example, manufactured from the same material. The contact bridge carrier 30 and the barrier 32 are advantageously manufactured as one piece.

[0049] Furthermore, the switching device 10 includes a magnetic drive assembly. The magnetic drive assembly may also be referred to as an electromechanical switching drive or magnetic actuator. The magnetic drive assembly includes an electric coil 48, a magnetic core 50, and an armature 47. The electric coil 48 is fixed in the magnetic core 50. The housing 35 is made, for example, of a thermoplastic or thermosetting material. The armature 47 is fastened to the contact bridge carrier 30. The armature 47 is coupled to the contact bridge 40 via the contact bridge carrier 30 and a contact spring 31. The contact spring 31 is made, for example, of steel, such as inox steel. The contact spring 31 presses the contact bridge 40 in the direction of the first and second terminal contacts 51, 52. The contact spring 31 fixes the contact bridge 40 in its target position. The contact spring 31 preloads the contact bridge with a defined force. The contact spring 31 ensures an adequate contact force when the switching device 10 is in the switched-on state. The contact spring 31 exerts a force on the contact bridge 40 in a direction towards the first and second fixed contacts 55,56.

[0050] The switching device 10 includes at least stoppers, for example a first and a second stopper 71, 72. The first and second stoppers 71, 72 protrude from the housing 35. The first and second stoppers 71, 72 are, for example, integrally connected to the housing 35. In this case, the stoppers 71, 72 are, for example, made of the same material as the housing 35. The first stopper 71 includes an opening 73 and the second stopper 72 includes an opening 74. The first and second stoppers 71, 72 may have the form of a hollow cylinder (also called a cylindrical shell) or an elongated hollow cylinder.

[0051] Further, the switching device 10 includes a first arc runner 25 connected to the first terminal contact 51. Further, the switching device 10 includes a second arc runner 26 connected to the contact bridge 40 near the first movable contact 45. In addition, the switching device 10 includes a third arc runner 27 connected to the second terminal contact 52. Further, the switching device 10 includes a fourth arc runner 28 connected to the contact bridge 40 near the second movable contact 46.

[0052] The first arcing chamber 21 of the switching device 10 is connected to a first arc runner 25. The second arcing chamber 22 of the switching device 10 is connected to a third arc runner 27. The first and second arcing chambers 21, 22 include a number of splitter plates (not shown). Furthermore, the switching device 10 is surrounded by a permanent magnet system (not shown) having a permanent magnet and first and second magnetic pole plates. The contact bridge 40, the first and second terminal contacts 51, 52, and the first and second arcing chambers 21, 22 are arranged between the first and second magnetic pole plates.

[0053] 1 to 4 show the operation of an example of a switching device 10. The switching device 10 is configured as a bidirectional DC switching device. The switching device 10 is configured to be set to a switched-on state or a switched-off state.

[0054] In Fig. 1, an example of a switching device 10 is shown in a switched-off state. In other words, the switching device 10 is operationally in a switched-off state (normally switched-off, no fault case). In the switched-off state of the switching device 10, the contact bridge 40 is in an OFF position. In the switched-on state of the switching device 10, the contact bridge 40 is in an ON position.

[0055] In the switched-off state, the first and second fixed contacts 55, 56 are not in contact with the first and second movable contacts 45, 46. Thus, the flow of load current from the first terminal contact 51 to the second terminal contact 52 through the contact bridge 40 is prevented. The switching device 10 is set from the switched-on state to the switched-off state by the movement of the contact bridge 40 which separates it from the first and second terminal contacts 51, 52. This movement is brought about by the movement of the armature 47 of the magnetic drive assembly to which the contact bridge 40 is coupled. If a load current flows before switching, a first arc is generated between the first fixed contact 55 and the first movable contact 45 and a second arc is generated between the second movable contact 46 and the second fixed contact 56.

[0056] The clearing distance B is the distance of the movement of the contact bridge 40 from the ON position of the contact bridge 40 to the OFF position of the contact bridge 40. In other words, the clearing distance B is the distance between the surface of the first fixed contact 55 and the surface of the first movable contact 45. The switching device 10 is, for example, symmetrical about the central axis. Thus, the clearing distance B is equal to or approximately equal to the further clearing distance B' between the surface of the second fixed contact 56 and the surface of the second movable contact 46. Due to manufacturing tolerances and the influence of previous arcs, the clearing distance B and the further clearing distance B' may not be identical. In the switched-off state of the switching device 10, there is an air gap 49 between the armature 48 and the magnetic core 50.

[0057] At the transition from the switched-on state to the switched-off state, the armature 47 pulls the contact bridge carrier 30 and the contact bridge 40 away from the first and second terminal contacts 51, 52. A travel distance C of the armature 47 can also be referred to as the travel distance of the magnetic drive assembly and is shown in FIG. 1. The travel distance C is the distance the armature 47 is moved from the switched-on state of the switching device 10 to the switched-off state. The clearing distance B and the travel distance C can be measured, for example, by a device for length or distance measurement when the switching device 10 is not operated and is open. Typically, the switching device 10 is a normally-off device. The device for length or distance measurement is, for example, a laser distance measuring device or a laser triangulation device or a caliper. In general, the stroke or travel of the armature 47 is easily measured by such a device for length or distance measurement. Parameters that cannot be measured directly can be calculated.

[0058] Figure 2 shows an example of the switching device 10 shown in Figure 1 in a switched-on state, where contact between the pole faces of the armature 47 and the magnetic core of the magnetic drive assembly, together with the contact spring 31, causes the closing of the contact bridge 40 and the contact of the two movable contacts 45, 46 with the two fixed contacts 55, 56 with a contact force configured for the permanent conduction of a rated current. Thus, the load current can flow from the first terminal contact 51, through the first fixed contact 55, the first movable contact 45, the contact bridge 40, the second movable contact 46 and the second fixed contact 56 to the second terminal contact 52.

[0059] The over-travel A is shown in FIG. 2. The over-travel A is the distance by which the armature 47 is moved beyond the point where both of the movable contacts 45, 46 contact both of the fixed contacts. The contact spring 31 is thus compressed by the contact bridge carrier 30. The contact spring 31 becomes shorter by the over-travel A compared to the released contact spring 31. The over-travel A can be measured or calculated. The contact spring 31 is slightly compressed compared to the switched-off state to exert a contact force suitable for the flow of persistent current. Advantageously, the over-travel A ensures that the switching device 10 is in the switched-on state even in the case of a reduction in the thickness of the movable contacts 45, 46 or the fixed contacts 55, 56 as an effect of vibrations applied to the switching device 10 or of previous arcs.

[0060] FIG. 3 shows an example of the switching device 10 shown in FIG. 1 and FIG. 2 in the case of a short circuit. The term "short circuit case" can be replaced by the term "short circuit event", for example. In FIG. 3, the first phase of the short circuit is illustrated. In the first phase of the short circuit (e.g. with a high short circuit current), a dynamic tearing open of the movable contacts 45, 46 occurs. In this case shown in FIG. 3, the contact bridge 40 moves downwards, while the armature 47 is still in the position of the switched-on state of the switching device 10. The contact spring 31 is highly compressed. The compression of the contact spring 31 in the first phase is higher than the compression of the contact spring 31 in the switched-on state of the switching device 10.

[0061] In the first phase of the short circuit, the contact bridge 40 moves relative to the housing 35 or the two fixed contacts 55, 56, and the contact bridge carrier 30 does not move. The contact bridge 40 thus moves relative to the contact bridge carrier 30. The movement of the contact bridge 40 from the on position is limited in the case of a short circuit to an end stop distance F. The relative movement of the contact bridge 40 with respect to the contact bridge carrier 30 can attain at most the end stop distance F.

[0062] In one example, the movement is stopped by the contact spring 31. The contact spring 31 has a minimum length, called the block length. The block length is the length of the contact spring 31 at full blocking. The block length is the length of the contact spring 31 at maximum compression, so that each winding contacts the adjacent winding. When the contact spring 31 is compressed to its block length, the relative movement of the contact bridge 40 towards the contact bridge carrier 30 is stopped. The movement of the contact spring 31 can be stopped by the block length of the contact spring 31 or by at least bumpers 75, 76 in the contact bridge carrier 30 (as shown in FIG. 5). The end stop distance F can be measured, for example, by a device for length or distance measurement when the switching device 10 is opened without being operated and the contact bridge 40 is moved relative to the contact bridge carrier 30 by an external force. The end stop distance F is the distance between the two end positions of the inner contact bridge 40 of the contact bridge carrier 30 (eg the end stop distance F is this distance minus the over-travel distance A).

[0063] FIG. 4 shows an example of the switching device 10 shown in FIGS. 1-3 in the case of a short circuit. In FIG. 4, the second phase of the short circuit is illustrated. The switching device 10 comprises at least one stopper, for example realized as a first and a second stopper 71, 72. The first and second stoppers 71, 72 are connected to the housing 35. In the event of a short circuit, the current sensor detects that the load current exceeds a predetermined limit and provides a signal to the control circuit which triggers a movement of the armature 47 towards the position of the armature 47 in the switching-off state of the switching device 10. Thus, the contact bridge carrier 30 is caused to move.

[0064] The first and second stoppers 71, 72 limit the movement of the contact bridge 40 relative to the housing 35 in the second phase of the short circuit. The maximum clear distance E is the maximum distance of movement of the contact bridge 40 from the on position of the contact bridge 40 in the switched-on state of the switching device 10 to the at least one stopper 71, 72 in the case of a short circuit. The maximum clear distance E is, for example, the distance of the first fixed contact 55 to the first stopper 71 (parallel to the direction of movement of the contact bridge 40) minus the thickness of the contact bridge 40. This distance and the thickness of the contact bridge 40 can be measured by a device for length or distance measurement on an open, power-free switching device 10. The maximum clear distance E is greater than the end stop distance F. The difference distance D can be calculated as follows:

number

[0065] FIG. 5A shows a detail of an example of a contact area of ​​the switching device 10, which is a further development of the example shown in FIGS. 1 to 4. In FIG. 5, the first phase of the short circuit is shown similarly to FIG. 3. The movement of the contact bridge 40 is stopped by a mechanical part of the switching device 10, which is arranged between the contact bridge 40 and the contact bridge carrier 30. The mechanical part is, for example, a first bumper 75, which is connected to the contact bridge carrier 30. The first bumper 75 stops the movement of the contact bridge 40. The contact bridge carrier 30 may include the first bumper 75. The contact bridge carrier 30 and the first bumper 75 are, for example, made from the same material. The first bumper 75 is formed, for example, as a pin, cylinder or bar. As shown in FIG. 5, the switching device 10 includes a second bumper 76. The second bumper has the same function and structure as the first bumper 75. The two bumpers 75, 76 and a part of the contact bridge 40 are shown in dashed lines. 3, because they are “behind” the front plate of the contact bridge carrier 30 .

[0066] In an alternative, not shown, embodiment, the first bumper 75 is realised by a transverse rib in the contact bridge carrier 30. The transverse rib is, for example, part of the plastic of the contact bridge carrier 30. Advantageously, no additional parts are required. The switching device 10 is devoid of a second bumper 76.

[0067] FIG. 5B shows further details of an example of a switching device 10, which is a further development of the above example. In FIG. 5B, two cross sections in different planes are shown. The cross section to the left of the dotted line is a cross section through the contact bridge 40, whereas the cross section to the right of the dotted line is a cross section through a plane behind the contact bridge 40. As shown to the right of the dotted line, the switching device 10 includes a return spring 77. One side of the return spring 77 contacts the housing 35. The other side of the return spring 77 is coupled to the contact bridge carrier 30. A metal bridge 78 of the switching device 10 couples the other side 78 of the return spring 77 to the contact bridge carrier 30. In the switched-on state of the switching device 10 (as shown in FIG. 5B), the coil current flows through the coil 48, and thus the armature 47 is pulled towards the magnetic core 50. More precisely, when the switching device 10 is switched from the switched-off state to the switched-on state, the coil current has a first value for a first duration and then a second value. The second value is smaller than the first value. The second value is for example 20% or 10% or 5% lower than the first value. Advantageously, in the first duration, a high force is achieved by a high value of the coil current to move the armature 47 quickly. A lower value of the coil current is appropriate to hold the armature 47 in the switched-on position.

[0068] 5C shows further details of an example of switching device 10 that is a further development of the above example. In FIG. 5C, the same cross section is shown as in FIG. 5B. In the switching-off state of switching device 10 (as shown in FIG. 5C), no coil current flows through coil 48, and thus an air gap 49 is between armature 47 and magnetic core 50.

[0069] The contact bridge carrier 30 includes a limiter 82. The contact bridge carrier 30 and the limiter 80 are made from the same material. The limiter 82 is configured to limit the movement of the contact bridge 40 inside the contact bridge carrier 30 towards the first and second fixed contacts 55, 56. Thus, the contact bridge 40 can move inside the contact bridge carrier 30 between the limiter 82 and the first bumper 75.

[0070] The return spring 77 holds the contact bridge carrier 30, and thus the contact bridge 40, at a distance to the first and second terminal contacts 51, 52 in the switched-off state of the switching device 10. The return spring 77 exerts a force on the contact bridge carrier 30 in a direction away from the first and second fixed contacts 55, 56.

[0071] 6A-6C show different example characteristics of the switching device 10, for example, realized in the above example. In Fig. 6A-6C, the short circuit current IL and the voltage VL are shown as a function of time t. The short circuit current IL flows from the first terminal contact 51 to the second terminal contact 52 through the contact bridge 40, with or without an arc. A voltage VL is tapped between the first terminal contact 51 and the second terminal contact 52. A shunt resistor is inserted in the circuit, for example, between the second terminal contact 52 and a reference potential. The shunt resistor has a value of, for example, 60 μΩ. The voltage across the shunt resistor has a value of 150 mV at a load current IL of 2500 A. In Fig. 6A-6C the results of the measurements are shown. Each figure shows a short circuit.

[0072] In FIG. 6A, the short circuit current IL rises due to the short circuit, resulting in the above-mentioned movement of the contact bridge 40. Thus, an arc is generated between the movable contacts 45, 46 and the fixed contacts 55, 56. The arc is quickly extinguished. In one example, the short circuit current IL reaches a value of 20 kA without the actuation of the switching device 10. Since the actuation of the switching device 10 is fast, the short circuit current IL reaches, for example, 17500 A and thus remains below the nominal value of 20 kA for the short circuit current. The voltage VL rises after the start of the movement of the contact bridge and remains at about 800 V. FIG. 6A shows an example of a switching device 10 with optimized parameter values, as described below in FIG. 7A.

[0073] In Fig. 6B, the switching device 10 shows a longer extinguishing time compared to the switching device 10 of Fig. 6A. The maximum clearing distance E has a value that is too small. The long extinguishing time increases the risk that the arc will result in a large amount of material of the movable and fixed contacts 45, 46, 55, 56 being melted. The melted material may block the movement of the arc into the arc chambers 21, 22. As shown in Fig. 6B, the arc is finally extinguished and a voltage VL of about 800V is dropped between the first terminal contact 51 and the second terminal contact 52.

[0074] In Fig. 6C, the switching device 10 shows a short extinguishing time, similar to the situation shown in Fig. 6A. However, the contact bridge 40 returns to the first and second fixed contacts 55, 56, and the short circuit current IL rises again. After a long extinguishing time, the short circuit current IL falls again and the voltage VL obtains a value of 800 V. In Fig. 6C, the maximum clearing distance E has a too high value (e.g., E = 9 mm).

[0075] Figure 7A shows an example of values ​​of parameters of the switching device 10, which is a further development of the above example. The value of the end stop distance F is shown as a function of the value of the maximum clear distance E. The values ​​of the end stop distance F, the clear distance B and the maximum clear distance E are given in mm (5,1 mm means 5100 μm). Figure 7A shows the results of a one-dimensional multi-physics simulation. The region of the end stop distance F marked in black results in an actuated switching device 10.

[0076] For a given value E for the maximum clear distance, the switching device 10 will operate correctly for a value F of the end stop distance, provided that:

number

number

[0077] Thus, the end stop distance has a value F according to the following formula:

number

[0078] These values ​​of the maximum clear distance E and the end stop distance F result in a switching device 10 that operates correctly even in the case of a short circuit. For example, with a value E=7.2 mm for the maximum clear distance, the value F of the end stop distance is Fmin=5.3 mm≦F≦6.1 mm=Fmax. In this example, the clear distance obtains, for example, a value B=5.6 mm. The value of the maximum clear distance E depends on the value of the clear distance B. The value of the end stop distance F also has a small dependence on the value of the clear distance B. The clear distance B obtains a value in the range of 5.1 mm to 6.6 mm. In other words, the value of the clear distance B depends on the value of the maximum clear distance E. The value of the maximum clear distance E depends on the value of the end stop distance F.

[0079] The maximum clear distance E has a value in the range of 6.3 mm to 8.6 mm. Thus, the maximum clear distance E and the end stop distance F are the most important parameters for the switching device 10 to operate correctly even in the case of a short circuit. In one example, the values ​​obtained from the formula are rounded.

[0080] In one example, the end stop distance F, the maximum clear distance E and other distances are measured with a device suitable for measuring the dimensions of an object. The distances are measured by a device for length or distance measurement, for example by a laser or a caliper. The caliper allows the measurement result to be read on a ruled scale, a dial or a digital display.

[0081] The region of the end stop distance E marked in white results in a switching device 10 that is not operating correctly. For example, parameter values ​​in the lower left region of the table result in a reconnection in the case of a short circuit with a short circuit current of 20 kA. The arc does not move into the arc chambers 21, 22. Parameter values ​​in the upper right region of the table result in difficulties in the case of short short circuit currents. Reconnection may also occur with these parameter values.

[0082] The value of the over travel distance A is independent of, for example, the end stop distance F and the maximum clear distance E. The travel distance C can be calculated, for example, using C=B+A. The values ​​of the clear distance B, the travel distance C and the difference distance D result, for example, from the selection of the values ​​of the end stop distance F and the maximum clear distance E.

[0083] The embodiments shown in Figures 1-7 as described above illustrate examples of the improved switching devices 10 and methods. As such, they do not constitute an exhaustive list of all embodiments according to the improved switching devices and methods. Actual switching devices and methods may differ from the illustrated embodiments, for example, in terms of components, structure, and shape. [Prior art documents] [Patent documents]

[0084] [Patent Document 1] International Publication No. 2020 / 035489A1 [Explanation of symbols]

[0085] 10 Switching Devices 21,22 Arc chamber 25~28 Arc Runner 30 Contact Bridge Carrier 31 Contact spring 35 Housing 40 Contact Bridge 45,46 Movable contact 47 Armature 48 Electric Coil 49 void 50 Magnetic Core 51 First terminal contact 52 Second Terminal Contact 55,56 fixed contact 71 First Stopper 72 Second Stopper 73,74 aperture 75,76 Bumper 77 Return spring 78 Metal Bridge 79,80,81 Armature connection 82 Limiter A. Excessive mileage B Clear Distance C. Mileage D Difference Distance E Maximum clear distance F Endstop Distance IL Short circuit current VL Voltage

Claims

1. first and second fixed contacts; - contact bridges, - first and second movable contacts arranged on said contact bridge; - contact springs, a contact bridge carrier, which is movable and which is coupled to the contact bridge via the contact spring; a magnetic drive assembly having an electric coil, a magnetic core and an armature, said armature being movable and connected to said contact bridge carrier; - a housing; at least one stop connected to the housing and configured to limit the movement of the contact bridge in the event of a short circuit; a switching device.

2. 2. The switching device according to claim 1, configured such that in the event of a short circuit, a current flows through the first fixed contact, the first movable contact, the contact bridge, the second movable contact and the second fixed contact, and movement of the contact bridge carrier causes movement of the contact bridge from its on position to the at least one stop in a switched-on state of the switching device.

3. 3. The switching device according to claim 2, wherein a maximum clearing distance is the maximum distance of movement of the contact bridge from the on position of the contact bridge in the switched-on state of the switching device to the at least one stop in the event of a short circuit.

4. 10. The switching device of claim 1, wherein the at least one stopper and the portion of the housing connected to the at least one stopper are made of the same material.

5. 5. The switching device according to claim 1, wherein the contact bridge carrier and the contact bridge are configured such that in the switched-on state of the switching device, a relative movement of the contact bridge with respect to the contact bridge carrier from an on position of the contact bridge is limited to an end stop distance in the event of a short circuit.

6. The relative movement of the contact bridge with respect to the contact bridge carrier from the ON position of the contact bridge in the switched-on state of the switching device is at least one bumper connected to the contact bridge carrier, and / or - the block length of the contact spring 6. The switching device of claim 5, wherein the switching device is limited by:

7. The switching device of claim 5 , wherein the end stop distance is dependent on a maximum clear distance.

8. The end stop distance has a value F according to the following formula: [Equation 1] where Fmin and Fmax are the minimum and maximum values ​​of the end stop distance, and E is the value of the maximum clear distance.

8. The switching device of claim 7.

9. 5. A switching device as claimed in claim 1, wherein the clearing distance is the distance travelled by the contact bridge from its on position in a switched-on state of the switching device to its off position in a switched-off state of the switching device in the absence of a short circuit.

10. The switching device of claim 9 , wherein a maximum clear distance is greater than the clear distance.

11. The maximum clear distance has a value E according to the following formula: [Equation 2] where B is the value of the clear distance.

10. The switching device of claim 9.

12. the contact bridge carrier includes a limiter; the limiter is configured to limit movement of the contact bridge inside the contact bridge carrier towards the first and second fixed contacts. A switching device according to any one of claims 1 to 4.

13. the switching device includes a return spring; one side of the return spring is in contact with the housing and another side of the return spring is coupled to the contact bridge carrier; the return spring is configured to provide a force on the contact bridge carrier in a direction away from the first and second fixed contacts. A switching device according to any one of claims 1 to 4.

14. A switching device according to any one of claims 1 to 4, wherein the housing is configured to limit movement of the armature in the event of a short circuit.

15. 1. A method of operating a switching device, comprising: the switching device includes first and second fixed contacts, a contact bridge, first and second movable contacts arranged on the contact bridge, a contact spring, a movable contact bridge carrier coupled to the contact bridge via the contact spring, a housing, at least one stopper connected to the housing, and a magnetic drive assembly having an electric coil, a magnetic core and an armature, the armature being movable and connected to the contact bridge carrier; the method comprising limiting the movement of the contact bridge by the at least one stop in the event of a short circuit. method.

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