Switching device

Abstract

Switching device (100) comprising at least one fixed contact (2, 3), a contact bridge (4) and an upper yoke element (50) in a switching chamber (11), wherein the contact bridge (4) has a top surface with at least one contact area and a bottom surface opposite the top surface and is movable by means of a magnetic armature (5) with an axis (7), at least one contact area of ​​the contact bridge (4) in an switched-on state of the switching device (100) is in mechanical contact with the at least one fixed contact (2, 3), the axis (7) is located on the underside of the contact bridge (4), the upper yoke element (50) is arranged on the top of the contact bridge (4) and is attached to the switching chamber (11), the upper yoke element (50) has a recess (52) on one of the undersides facing the contact bridge (4) and the contact bridge (4) projects at least partially into the recess (52) when the switching device (100) is switched on.

Description

[0001] A switching device is specified.

[0002] The switching device is designed, in particular, as an electromagnetically operated, remotely controlled switch that can be operated by an electrically conductive current. The switching device can be activated via a control circuit and can switch a load circuit. In particular, the switching device can be designed as a relay or as a contactor, especially as a power contactor. Particularly preferably, the switching device can be designed as a gas-filled power contactor.

[0003] One possible application of such switching devices, in particular power contactors, is the opening and disconnecting of battery circuits, for example in motor vehicles such as electrically or partially electrically powered vehicles.

[0004] In its function as a safety component, a contactor is typically used in combination with a fuse between a battery, such as a lithium-ion battery, and an electric motor. In the event of a malfunction, it must be able to disconnect the power source from the load. A serious case of battery malfunction is a short circuit within the battery, which, depending on the battery's state of charge, can lead to very rapid discharge with currents in the kiloampere range, and thus many times the nominal current. The contactor's main task in such a case is to carry this very high current for a short time, for example, in the millisecond range, until the upstream fuse can safely interrupt the current or the current decreases due to an increasing internal resistance of the battery.

[0005] A contactor typically has a switching bridge that is moved by a magnetic drive. When the contactor is switched on, this bridge electrically connects, for example, two fixed main contacts. However, when a high short-circuit current occurs, strong Lorentz forces arise due to the magnetization of the conductors, which push the switching bridge away from the main contacts. This phenomenon is also known as levitation. Levitation can cause an unwanted arc to form between the main contacts and the bridge, which burns at a very high temperature. This can destroy the contactor.

[0006] A magnetic field proportional to the current strength forms around a current-carrying conductor. In existing solutions, the magnetic field generated by the current flowing in the contactor bridge is concentrated in iron parts, causing them to attract each other. This attractive force is also known as reluctance force, which can be used to press the contactor bridge more firmly against the main contacts and prevent the contactor from opening.

[0007] For example, publication CN 209000835 U describes an anti-levitation device in which a switching bridge is pre-tensioned with a compression spring and held between an insulator and a retaining cage. The switching bridge is divided in the middle into two current paths. Both paths are enclosed by an iron plate and an iron clamp, with the iron plates being locked to the retaining cage and the iron clamps being attached to the switching bridge.

[0008] When an electric current flows through the switching bridge, a magnetic flux forms around each current path and is concentrated in the respective iron parts. An attractive force acts between the iron parts, tending to close the air gap. This force further presses the switching bridge against the main contacts, preventing it from opening. The air gap itself remains constant and is determined solely by the design of the components. The maximum holding force, and therefore the maximum short-circuit current, is thus limited by the following parameters: the force of the compression spring, the cross-section of the iron parts, the holding force of the magnetic drive, and the size of the air gap.

[0009] The documents EP 2 608 235 B1 and DE 10 2016 206 130 A1 also describe anti-levitation devices, but in these devices there is no division of the switching bridge into several current paths and therefore only one iron pairing is present.

[0010] Further switching devices are known from the publications JP 2014 - 157829 A, JP 2012 - 212668 A and EP 2 608 235 B1.

[0011] Document US 2020 / 0035433A1 describes a relay with a switching device having fixed contacts and a movable contact by means of a magnetic drive. The movable contact is pressed towards the fixed contacts by a spring located between a holder fixed to a base and the movable contact. The magnetic drive moves the movable contact away from the fixed contacts against the force of the spring, while when the magnetic drive is disengaged, the spring presses the movable contact against the fixed contacts. A yoke is attached to the base between the fixed contacts. When current flows through the movable contact, this yoke exerts an electromagnetic force on the contact, counteracting a levitation force.Since the magnetic drive is located below the yoke when viewed from the moving contact, the yoke has an opening in the form of a through hole or a slot through which a non-magnetic shaft of the magnetic drive protrudes.

[0012] At least one function of certain embodiments is to specify a switching device.

[0013] This problem is solved by the subject matter according to the independent patent claim. Advantageous embodiments and further developments of the subject matter are characterized in the dependent claims and are further described in the following description and drawings.

[0014] According to at least one embodiment, a switching device has at least one fixed contact and at least one movable contact. The movable contact can, in particular, include or be a contact bridge. In other words, the contact bridge can be a movable contact of the switching device or part of a movable contact of the switching device. The properties and features of the movable contact described below can therefore be corresponding properties and features of the contact bridge, and vice versa. The switching device can particularly preferably have a contact arrangement that includes the movable contact, i.e., the contact bridge.

[0015] The at least one fixed contact and the at least one movable contact are designed and configured to switch a load circuit connectable to the switching device on and off. The movable contact, in particular the contact bridge of the contact arrangement, is movable within the switching device between a non-switching state and a switching state such that, in the non-switching state of the switching device, the movable contact, in particular the contact bridge of the contact arrangement, is spaced away from the at least one fixed contact and thus galvanically isolated, and in the switching state has a mechanical contact with the at least one fixed contact and is thus galvanically connected to it.In the following, the switching state will also be referred to as the switched-on state of the switching device, while the non-switching state will be referred to as the switched-off state of the switching device.

[0016] The switching device preferably has at least two fixed contacts arranged separately within the device. Depending on the state of the movable contact, and in particular the contact bridge, these contacts can be electrically connected or disconnected by the movable contact, as described above. The contact bridge preferably has a top surface with at least one contact area and a bottom surface opposite the top surface. In the switching state of the device, the at least one contact area of ​​the contact bridge is in mechanical contact with the at least one fixed contact, and in particular, with a contact area of ​​the at least one fixed contact. If the switching device has, for example, two fixed contacts, the contact bridge can accordingly have two contact areas.

[0017] The general term "contacts" hereafter can refer in particular to all fixed contacts as well as to the contact bridge or the contact arrangement with the contact bridge. In particular, the contacts can comprise or be made of a metal, preferably copper or a copper alloy. Furthermore, at least for the contact areas, a composite material in the form of a metallic matrix material, preferably with or made of copper, and particles distributed therein, preferably with or made of a ceramic material such as aluminum oxide, is also possible.

[0018] According to a further embodiment, the switching device has a housing in which the contact arrangement and the at least one fixed contact or at least two fixed contacts are arranged. The contact arrangement can, in particular, be completely enclosed within the housing. The fact that a fixed contact is arranged within the housing can, in particular, mean that at least the contact area of ​​the fixed contact, which is in mechanical contact with the movable contact in the switching state, is located within the housing. For connecting a supply line of a circuit to be switched by the switching device, a fixed contact arranged within the housing can be electrically contactable from the outside, i.e., from outside the housing. For this purpose, a fixed contact arranged within the housing can protrude a portion from the housing and have a connection point for a supply line outside the housing.

[0019] According to a further embodiment, the contacts are arranged in a gas atmosphere within the housing. This can particularly mean that the contact arrangement is completely immersed in the gas atmosphere within the housing and that, furthermore, at least parts of the stationary contact(s), such as the contact area(s), are also arranged in the gas atmosphere within the housing. Accordingly, the switching device can preferably be a gas-filled switching device, such as a gas-filled contactor.

[0020] According to a further embodiment, the contacts, meaning the contact arrangement in its entirety as well as at least parts of the stationary contact(s), are arranged in a switching chamber within the housing. The switching chamber can contain a gas, i.e., at least a portion of the previously described gas atmosphere. The gas preferably contains at least 20% H₂ and more preferably at least 50% H₂. In addition to hydrogen, the gas can contain an inert gas, particularly preferably N₂ and / or one or more noble gases.

[0021] According to a further embodiment, the contact bridge in the switching device is movable by means of an axle. Particularly preferably, the contact arrangement in the switching device is movable by means of the axle. In particular, the contact bridge, and especially preferably the contact arrangement, can be movable by means of a magnetic armature that includes the axle. The axle can be connected at one end directly or indirectly to the contact bridge in such a way that the contact bridge is movable by means of the axle, i.e., it is also moved when the axle is moved by it. Particularly preferably, the axle can be connected at one end to the contact arrangement in such a way that the contact arrangement is movable by means of the axle, i.e., it is also moved when the axle is moved by it. The axle can, in particular, project into the switching chamber through an opening in the switching chamber.The magnetic armature can be moved by a magnetic circuit to effect the switching operations described above. For this purpose, the magnetic circuit can include a yoke with an opening through which the axis of the magnetic armature protrudes. The axis is preferably made of or consisting of stainless steel. The yoke is preferably made of or consisting of pure iron or a low-doped iron alloy.

[0022] According to a further embodiment, the contact arrangement has a retaining element. The retaining element can, in particular, be attached to the shaft. Furthermore, the retaining element, and thus the contact arrangement, can be locked to the shaft. This can be achieved, for example, by means of a snap ring or a rivet. In addition, the retaining element, and thus the contact arrangement, can be screwed onto the shaft. For this purpose, the retaining element can, for example, have a threaded hole or a formed threaded bushing with a thread, with which the retaining element can be screwed onto a thread of the shaft. In this case, the retaining element can also be locked to the shaft, for example, also by means of a snap ring and / or a rivet and / or a lock nut.Furthermore, it is also possible that the axle is secured in the retaining element by a clamping mechanism and / or that part of the axle is formed with the material of the retaining element. In this case, the axle may preferably have one or more anchoring elements, such as one or more grooves and / or one or more projections, which may extend completely or partially around the axle.

[0023] According to a further embodiment, the switching device has an upper yoke element. The upper yoke element is particularly preferably arranged separately from the contact bridge and particularly preferably separately from the contact arrangement in the switching device. In particular, the upper yoke element can be arranged and fixed immovably in the switching device.

[0024] According to a further embodiment, the switching device has a lower yoke element in addition to the upper yoke element. In particular, the contact arrangement includes the lower yoke element. The lower yoke element is thus preferably part of the contact arrangement.

[0025] The upper yoke element, or the upper yoke element and the lower yoke element, may each contain or be made of iron. In particular, the upper yoke element, or the upper yoke element and the lower yoke element, may each contain or be made of pure iron.

[0026] Preferably, the upper yoke element, unlike the lower yoke element, is not part of the contact arrangement but is independent of it. Thus, if the contact arrangement includes the lower yoke element, it is arranged independently of the lower yoke element within the switching chamber. Particularly preferably, the upper yoke element is arranged and locked in a fixed position relative to the at least one stationary contact. The upper yoke element can be attached to the switching chamber. For example, the upper yoke element can be attached to an inner surface of the switching chamber, preferably by soldering or bonding. Alternatively, the upper yoke element can also be attached to the switching chamber by riveting or screwing. Furthermore, the upper yoke element can be held on the inner surface of the switching chamber, for example, by means of a fastening element, such as one made of plastic.For example, the upper yoke element can be fixed in the switching chamber by crimping. The upper yoke element can be loosely inserted into the switching chamber or a portion thereof and, preferably during assembly, locked in place by clamping or crimping. Because the upper yoke element is not part of the contact assembly, it is advantageously achieved, in contrast to the prior art described above, that the upper yoke element does not move along with the switching movement of the contact assembly. This allows the upper yoke element to be, for example, larger than conventional yoke elements in the prior art, since its mass is negligible with regard to the switching movement.

[0027] According to a further embodiment, the lower yoke element is slidably mounted on the retaining element. Accordingly, the position of the lower yoke element relative to the upper yoke element can change, firstly, through movement of the lower yoke element within the contact arrangement. This allows the air gap between the lower and upper yoke elements to be altered, particularly when the switching device is switched on. Secondly, in the preferred case where the upper yoke element is attached to the switching chamber, the position of the lower yoke element relative to the upper yoke element can change through movement of the contact arrangement within the switching chamber. It is particularly preferred that the lower yoke element is slidably mounted on the retaining element in a direction parallel to the axis.

[0028] According to another embodiment, the contact bridge is arranged on the retaining element. In particular, the contact bridge can be slidably mounted on the retaining element. Preferably, the contact bridge can be slidably mounted on the retaining element in a direction parallel to the axis.

[0029] The fact that an element, in particular the lower yoke element and / or the contact bridge, is slidably mounted on the retaining element can mean, in particular, that said element is movable in preferably only one direction, which can also be referred to as the direction of movement, with respect to the retaining element, and at the same time its freedom of movement is restricted by the retaining element. The restriction of the freedom of movement can be along the direction of movement, so that the slidability along the direction of movement is limited to a certain distance. Preferably, the freedom of movement in directions other than the direction of movement is, within tolerances, at least significantly restricted.

[0030] Particularly preferred, if the lower yoke element is present, is the mounting of the contact bridge, the lower yoke element, and the upper yoke element in pairs so as to be movable relative to each other. This means that the contact bridge and the lower yoke element are mounted so as to be movable relative to each other, since the contact bridge and / or the lower yoke element are movably mounted on the retaining element. Furthermore, the contact bridge and, if present, the lower yoke element are mounted so as to be movable relative to the upper yoke element. This can be achieved, for example, by making the contact bridge and, if present, the lower yoke element part of the movable contact arrangement, whereas the upper yoke element is not part of the contact arrangement.

[0031] For example, the retaining element can have at least one guide element for guiding the contact bridge and / or the lower yoke element. This guide element can, for example, be formed by a guide rail and can, in particular, provide guidance and thus enable movement along a direction parallel to the axis. The retaining element preferably has several guide elements. The guide elements can preferably also limit movement in directions other than the intended direction of movement. Furthermore, the retaining element can have at least one stop to limit the displacement of the contact bridge and / or the lower yoke element. This stop can, in particular, limit movement along the direction of movement, and thus preferably along the direction parallel to the axis. The retaining element preferably has several stops.

[0032] For example, the retaining element can have at least one clamping element comprising at least one guide element and at least one stop, and which at least partially engages the contact bridge and / or the lower yoke element. The at least one clamping element can, for example, be arranged on a base plate of the retaining element. In particular, the clamping element can have a stop that is connected to the base plate via two guide elements, such that the guide elements and the stop of the clamping element, together with the base plate, surround an opening. The contact bridge and / or the lower yoke element can project through the opening. The retaining element most preferably has at least two clamping elements.

[0033] According to a further embodiment, the contact bridge is arranged between the base plate of the retaining element and the upper yoke element. If the lower yoke element is present, the contact bridge is arranged between the lower yoke element and the upper yoke element. In particular, the upper yoke element can be arranged above the contact arrangement when viewed from the axis. The contact bridge can have a top and a bottom opposite the top, with the lower yoke element, if present, being arranged below the contact bridge and thus on the underside of the contact bridge, while the upper yoke element is arranged above the contact bridge and thus on the top side of the contact bridge.

[0034] According to a further embodiment, the upper yoke element has a recess on its underside facing the contact bridge. The recess can be designed, in particular, as a trough-like or groove-like depression. When the switching device is switched on, the contact bridge can partially project into the recess. In particular, the recess can have a width that, at least in the region of the recess, is greater than the width of the contact bridge. For example, the contact bridge can have a constriction, i.e., a region with a reduced width, wherein, when the switching device is switched on, the constriction is at least partially located in the recess of the upper yoke element. Furthermore, the recess can have a depth that, at least in the region of the recess, is equal to or substantially equal to the thickness of the contact bridge.Furthermore, the contact bridge can also have a thickness greater than the depth of the recess. During the transition from an off-state to an on-state of the switching device, the contact bridge can be drawn into the recess by the switching movement of the contact arrangement. The upper yoke element can thus at least partially encompass the contact bridge in an on-state. Preferably, the contact bridge can partially protrude from the recess in the on-state of the switching device.

[0035] Furthermore, the contact bridge can also be spaced away from the upper yoke element when switched on. In other words, the contact bridge may not have mechanical contact with the upper yoke element when switched on. Accordingly, an air gap may remain between the upper yoke element and the contact bridge even when switched on.

[0036] According to a further embodiment, the retaining element comprises an electrically insulating material. It is particularly preferred that the retaining element be made of one or more electrically insulating materials, so that the retaining element can be electrically insulating. The electrically insulating material(s) can be selected from polymers and ceramic materials, for example selected from polyoxymethylene (POM), particularly with the structure (CH2O) n, polybutylene terephthalate (PBT), glass fiber-filled PBT, and electrically insulating metal oxides such as Al₂O₃. In particular, the retaining element can electrically isolate the contact bridge, or preferably the contact bridge and the contact spring, as well as the lower yoke element, from the shaft. This allows the contact bridge to be electrically isolated from the components of the magnetic drive, especially from the other components of the magnetic armature. The retaining element can thus simultaneously provide support for the contact bridge and electrical isolation of the contact bridge.

[0037] For example, the upper yoke element can be arranged laterally next to the at least one fixed contact. Here and in the following, "lateral" refers to directions perpendicular to the axis of the magnetic armature. Particularly preferably, the switching device has two fixed contacts, and the upper yoke element is arranged between the two fixed contacts.

[0038] Furthermore, the retaining element may have a part, such as a stop as described above, which, when the switching device is switched on, projects into a gap between the at least one fixed contact and the upper yoke element. This can, for example, achieve electrical insulation of the upper yoke element from the at least one fixed contact. In the case of two fixed contacts between which the upper yoke element is arranged, the retaining element may preferably have two parts, such as two stops, each of which, when the switching device is switched on, can project into a gap between one of the fixed contacts and the upper yoke element.

[0039] According to a further embodiment, the contact arrangement also includes a spring, which can hereinafter also be referred to as the contact spring, and which is arranged on the underside of the contact bridge facing away from the upper yoke element. If the contact arrangement also includes the lower yoke element, the contact spring is thus arranged on the underside of the contact bridge facing the lower yoke element. The contact spring can particularly preferably press the contact bridge in the direction of the at least one stationary contact. During a switching operation of the switching device from an off state to an on state, the magnetic armature, and thus the axis and the contact arrangement, preferably move in a linear motion in the form of a lifting or lowering movement along the axis, which can also be described as a vertical direction.Preferably, the axis and, for example, a magnetic core of the magnetic armature have a vertical range of motion for the stroke movement that is larger than the switching gap formed by the distance between the at least one fixed contact and the contact bridge in the non-switching state. This can be achieved, for example, by ensuring that, in the off-state, a gap between the magnetic core and the yoke of the magnetic circuit, which can also be referred to as the movement gap, is larger than the switching gap. When the contact bridge abuts the at least one fixed contact, and thus when the switching gap is completely closed, the contact spring can compress, and the magnetic armature can continue to move until, for example, the magnetic core rests against the yoke.Thus, the magnetic tank with the contact arrangement can be an overtravel system in which the contact bridge is slidably mounted on the holding element. For example, the movement gap can be less than or equal to 1 mm, and particularly preferably about 0.5 mm larger than the switching gap. The contact spring can be compressed by the overtravel, increasing the contact pressure of the contact bridge on at least one fixed contact and achieving a certain degree of insensitivity to vibrations and mechanical shocks.

[0040] According to a further embodiment, the contact spring is arranged between the contact bridge and the base plate of the retaining element or, in the case of an existing lower yoke element, between the contact bridge and the lower yoke element, so that the contact spring tends to push the contact bridge and base plate or the contact bridge and the lower yoke element apart. The contact spring thus generates, in particular, a spring force that counteracts the approach of the lower yoke element to the base plate or to the contact bridge. The spring can be supported, preferably directly, on the underside of the contact bridge and on the base plate or on the lower yoke element. In the latter case, the lower yoke element can have a recess into which the spring projects and which can fix the position of the contact spring.If the switching device does not have a lower yoke element, the retaining element, in particular the base plate, may have a spring retainer that counteracts displacement of the contact spring on the retaining element. For example, the spring retainer may have or be formed from a pin that is surrounded by part of the contact spring.

[0041] When the switching device is energized, a magnetic field is induced in the upper yoke element when current flows through the contact bridge. Particularly in the case of a large current, such as a short-circuit current through the contact bridge, the magnetic field lines can concentrate on the upper surface of the upper yoke element. Since the field seeks the shortest path to minimize energy, the field is strongly compressed on the underside facing the contact bridge and through the contact bridge itself. This generates a reluctance force on the contact bridge, which counteracts the levitation force and can therefore also be described as an anti-levitation force. Thus, a holding effect can be achieved by the flow of the magnetic field from the upper yoke element through the contact bridge.

[0042] In the case where the switching device has the lower yoke element, the contact bridge is particularly preferably arranged between the upper and lower yoke elements as described above. In addition to the effect of the upper yoke element on the contact bridge described above, the yoke elements can also capture magnetic fields generated by current flowing through the contact bridge. This means that, in this case, the two yoke elements are magnetized by a magnetic field generated by the current-carrying contact bridge, creating an attractive force between them. Since the upper yoke element is arranged on the retaining element above the contact bridge, while the lower yoke element is arranged below the contact bridge, the resulting attractive force between the yoke elements can pull the lower yoke element upwards, i.e., towards the upper yoke element.This effect can amplify the holding effect described above. The contact spring allows the lower yoke element to exert a force on the contact bridge, thus pushing the contact bridge upwards and towards at least one fixed contact. The attractive force between the yoke elements is stronger the greater the electric current flowing through the contact bridge. However, since the contact spring tends to push the lower yoke element away from the contact bridge and thus also from the upper yoke element, and the lower yoke element is movably mounted on the holding element, the spring force can be greater than the attractive force between the yoke elements at sufficiently small electric currents through the contact bridge.Only when the attractive force between the yoke elements exceeds the spring force of the contact spring can the lower yoke element move towards the upper yoke element, thereby pressing the contact bridge more firmly against at least one stationary contact by means of the now more strongly compressed contact spring. This effectively counteracts the levitation effect described above, particularly in the case of a short-circuit current.

[0043] In the switched-on state of the switching device, an electric current can flow through the contact bridge as described, generating a magnetic flux that causes an attractive force between the contact bridge and the upper yoke element, and, if present, between the lower yoke element and the upper yoke element. If the contact arrangement includes the lower yoke element, the contact arrangement and the upper yoke element are designed such that, for an electric current below a certain threshold, the lower yoke element is positioned at a first distance from the upper yoke element, and for an electric current above the threshold, the lower yoke element is positioned at a second distance from the upper yoke element, the second distance being smaller than the first. The first and second distances can, for example, correspond to the respective size of the air gap, which thus decreases when the current threshold is exceeded.Accordingly, the air gap between the lower yoke element and the upper yoke element during operation of the switching device depends on an electric current flowing through the contact bridge.

[0044] Below the current threshold, the air gap, and thus the first distance, can be more than 1 mm, for example up to 3 mm or even up to 5 mm, and thus considerably larger compared to the prior art described above, where the air gap remains essentially constant. After exceeding the current threshold, the air gap, and thus the second distance, can be less than 1 mm and particularly preferably equal to 0 or at least approximately 0. In other words, after exceeding the current threshold, with a suitable geometric design of the contact arrangement and the upper yoke element, it is preferably possible for the lower yoke element to be drawn so close to the upper yoke element that the lower yoke element abuts the upper yoke element or at least an air gap of less than 1 mm is present.

[0045] The current threshold can be adjusted by appropriately selecting the spring constant of the contact spring, the geometric design and size of the yoke elements, and the first gap. In particular, the current threshold can be set so that electrical currents corresponding to normal operation of the switching device remain below the threshold. This ensures that, during normal operation and also for small short-circuit currents, the attractive force between the yoke elements is low due to the large air gap and the first gap, preventing an increased contact force from being generated between the contact bridge and the at least one fixed contact. The contact bridge is held against the at least one fixed contact solely by the contact spring.Only when the current threshold is exceeded by a higher short-circuit current does the lower yoke element move towards the upper yoke element, allowing stronger levitation forces to be compensated for by the attractive force of the yoke elements. The air gap is thus variable, as described, depending on the electric current flowing through the contact bridge, which also makes the holding force variable. It can be ensured that the additional holding force generated by the lower yoke element is only activated in the event of a short circuit, by the lower yoke element closing the magnetic circuit with the upper yoke element.

[0046] Because the upper yoke element of the switching device described here is preferably fixed directly to the switching chamber, it is no longer dependent on the holding force of the magnetic drive of the switching device and thus on the holding force of the coil, as is the case in the prior art described above. The upper yoke element of the switching device described here can therefore withstand large forces, in particular forces exceeding 500 N. In the prior art solutions, however, the forces exerted by yoke elements are typically limited to about 100 N, since they can only be as large as the holding force of the magnetic drive coil. Consequently, significantly higher short-circuit currents are possible with the switching device described here.While it has been shown that solutions known in the prior art are typically only suitable for short-circuit currents of up to 8 kA for a duration of 5 ms, tests with the switching device described here have shown that short-circuit currents of up to 16 kA are possible.

[0047] In comparison to the complex designs of the prior art, the anti-levitation effect described here is essentially achievable with only one additional component, namely the upper yoke element. As described above, the anti-levitation effect can be further enhanced with the additional lower yoke element, and thus with both the upper and lower yoke elements combined. Furthermore, it can be selectively activated. Regardless of the presence of the lower yoke element, the positioning of the upper yoke element on the switching chamber ensures that the upper yoke element does not move during switching. This reduces the dynamic mass, resulting in faster switching.

[0048] Further advantages, advantageous embodiments and further developments result from the exemplary embodiments described below in conjunction with the figures. Fig. Figure 1 shows a schematic representation of an example of a switching device, Fig. Figures 2A to 2F show schematic representations of sections and parts of a switching device according to an exemplary embodiment. Fig. Figure 3 shows a schematic representation of the effect of the upper yoke element on the contact bridge, Fig. 4A and Fig. Figure 4B shows schematic representations of parts of a switching device according to further embodiments, Fig. Figures 5A to 5D show schematic representations of sections and parts of a switching device according to an exemplary embodiment and Fig. Figures 6A to 6D show schematic representations of sections of a switching device according to further embodiments.

[0049] In the exemplary embodiments and figures, identical, similar, or similarly functioning elements may be designated with the same reference numerals. The depicted elements and their relative sizes are not to be considered to scale; rather, individual elements, such as layers, components, building elements, and areas, may be exaggerated for clarity and / or better understanding.

[0050] In Fig. Figure 1 shows an example of a switching device 100, which can be used, for example, to switch high electrical currents and / or high electrical voltages and which can be a relay or contactor, in particular a power contactor. Fig. Figure 1 shows a three-dimensional sectional view with a vertical cutting plane. The geometries shown are only examples and not to be understood as limiting; alternative configurations are also possible.

[0051] The switching device 100 has contacts 1, hereinafter also referred to as switching contacts, within a housing (not shown). The housing primarily serves as contact protection for the components arranged inside and is made of or comprised of a plastic, for example, PBT or glass fiber-reinforced PBT. In the example shown, the switching device 100 has two fixed contacts 2 and one movable contact in the form of a contact bridge 4 mounted on an insulator 3. The contact bridge 4 is designed as a contact plate. The fixed contacts 2, together with the contact bridge 4, form the switching contacts. Alternatively, other numbers of contacts 1, i.e., other numbers of fixed and / or movable contacts, are possible.The fixed contacts 2 and / or the contact bridge 4 can be made of or with Cu, a Cu alloy, one or more high-melting-point metals such as Wo, Ni and / or Cr, or a mixture of the aforementioned materials, for example copper with at least one other metal, for example Wo, Ni and / or Cr.

[0052] In Fig. Figure 1 shows the switching device 100 in a switched-off state, in which the contact bridge 4 is spaced apart from the stationary contacts 2, so that contacts 2 and 4 are galvanically isolated from each other. The illustrated design of the switching contacts, and in particular their geometry, are purely exemplary and not to be understood as limiting. Alternatively, the switching contacts can also be designed differently.

[0053] The switching device 100 has a movable magnetic armature 5, which essentially performs the switching movement. The magnetic armature 5 has a magnetic core 6, for example, made of or with a ferromagnetic material. Furthermore, the magnetic armature 5 has an axle 7, which is guided through the magnetic core 6 and is fixedly connected to the magnetic core 6 at one end. At the other end of the axle, opposite the magnetic core 6, the magnetic armature 5 has the contact bridge 4. The axle 7 can preferably be made of or with stainless steel.

[0054] For electrical isolation of the contact bridge 4 from the axis 7, the insulator 3, which can also be referred to as the bridge insulator, is arranged between them. To compensate for possible height differences and to ensure sufficient mechanical contact between the stationary contacts 2 and the contact bridge 4, a contact spring 34 is arranged below the contact bridge 4. This spring is supported by the insulator 3 and exerts a force on the contact bridge 4 in the direction of the stationary contacts 2.

[0055] The magnetic core 6 is surrounded by a coil 8. A current flow in the coil 8, which can be switched on externally by a control circuit, causes the magnetic core 6, and thus the entire magnetic armature 5, to move in the axial direction until the contact bridge 4 makes contact with the stationary contacts 2. In the illustration shown, the magnetic armature moves upwards for this purpose. The magnetic armature 5 thus moves from a first position, a rest position corresponding to the disconnected (i.e., non-conducting and therefore off) state, to a second position corresponding to the active (i.e., conducting and therefore switched-on) state. In the active state, the contacts 1 are galvanically connected to each other.

[0056] To guide the shaft 7 and thus the magnetic armature 5, the switching device 100 has a yoke 9, which may be made of pure iron or a low-doped iron alloy and forms part of the magnetic circuit. The yoke 9 has an opening in which the shaft 7 is guided. If the current flow in the coil 8 is interrupted, the magnetic armature 5 is moved back to its initial position by one or more springs 10. In the illustration shown, the magnetic armature 5 thus moves downwards again. The switching device 100 is then back in its rest state, in which the contacts 1 are open.

[0057] The direction of movement of the magnetic armature 5, and thus of the contact bridge 4, is hereinafter also referred to as the vertical direction 91. The arrangement direction of the fixed contacts 2, which is perpendicular to the vertical direction 91, is hereinafter referred to as the longitudinal direction 92. The direction perpendicular to both the vertical direction 91 and the longitudinal direction 92 is hereinafter referred to as the transverse direction 93. The directions 91, 92, and 93, which also apply independently of the described switching movement, are indicated in some figures for ease of orientation. Directions that are parallel to a plane spanned by the longitudinal direction 92 and the transverse direction 93, and thus perpendicular to the vertical direction 91, are also referred to as the lateral directions 90.

[0058] For example, when contacts 1 are opened, at least one arc can occur, which can damage the contact surfaces of contacts 1. This can lead to the risk that contacts 1 will "stick" together due to arc welding and can no longer be separated. The switching device 100 would then remain in the switched-on state, even though the current in coil 8 is switched off and the load circuit should therefore be disconnected. To prevent the formation of such arcs, or at least to aid the extinguishing of any arcs that do occur, contacts 1 can be located in a gas atmosphere, so that the switching device 100 can be designed as a gas-filled relay or gas-filled contactor.In particular, the contacts 1 are arranged within a switching chamber 11, for example formed by a switching chamber wall 12 and a switching chamber base 13, in a gas-tight region 14 formed by a hermetically sealed part, wherein the switching chamber 11 can be part of the gas-tight region 14. The gas-tight region 14 completely surrounds the magnetic armature 5 and the contacts 1, except for parts of the fixed contacts 2 intended for external connection. The gas-tight region 14, and thus also the interior 15 of the switching chamber 11, is filled with a gas. The gas-tight region 14 is essentially formed by parts of the switching chamber 11, the yoke 9, and additional walls.The gas that can be filled into the gas-tight area 14 through a gas filling nozzle during the manufacture of the switching device 100 can particularly preferably contain hydrogen, for example with 20% or more H2 in an inert gas or even with 100% H2, since hydrogen-containing gas can promote the extinguishing of electric arcs. Furthermore, so-called blow-out magnets, i.e., permanent magnets 16, can be present inside or outside the switching chamber 11. These magnets cause an extension of the arc gap and thus improve the extinguishing of the electric arcs.

[0059] The switching chamber wall 12 and the switching chamber base 13 can, for example, be made with or from a metal oxide such as Al2O3. Furthermore, plastics with sufficiently high temperature resistance are also suitable, for example, PEEK, PE, and / or glass fiber-filled PBT. Alternatively or additionally, the switching chamber 11 can also be made at least partially of POM, in particular with the structure (CH2O) n , exhibit. Such a plastic can be characterized by a comparatively low carbon content and a very low tendency to form graphite. Due to the equal proportions of carbon and oxygen, especially in (CH2O) n During heat-induced decomposition, and especially arc-induced decomposition, predominantly gaseous CO and H2 are produced. The additional hydrogen can intensify arc quenching.

[0060] The features of the switching device 100 described above are purely exemplary and not to be understood as limiting. For example, the switching device 100 can alternatively be designed as a gas-filled contactor without gas filling, instead of the described version. In particular, the above description of the example serves to illustrate the Fig. 1. To illustrate the function of switching devices.

[0061] The following are exemplary embodiments of a switching device 100, which, in comparison to the switching device of the Fig. 1 a contact arrangement 200 as well as an upper yoke element 50 or a lower yoke element 40 and an upper yoke element 50, which form an anti-levitation mechanism.

[0062] In the Fig. Figures 2A to 2F show various sections and parts of the switching device 100 according to an exemplary embodiment. Fig. Figure 2A shows a three-dimensional sectional view of part of the switching device 100 with the contact arrangement 200, while the Fig. Figures 2B to 2F show different views of parts of the switching device 100 and, in particular, the contact arrangement 200. The following description of the switching device 100 applies equally to all Fig. 2A to 2F. Unless otherwise stated, the following correspond to those in the Fig. The elements shown in 2A to 2F in connection with the Fig. 1. Elements explained.

[0063] In Fig. 2A is compared to the view of the Fig. Figure 1 additionally shows the housing 19 of the switching device 100. The contact arrangement 200 is arranged in the switching chamber 11, has the contact bridge 4 and a retaining element 30, and is attached to the axis 7. This allows the contact arrangement 200 to be moved by the magnetic drive described above to carry out the switching movements of the switching device 100.

[0064] Furthermore, the switching device 100 has an upper yoke element 50. The upper yoke element 50 can be made of or consist of iron. In particular, the upper yoke element 50 can be made of or consist of pure iron. The contact bridge 4 is arranged below the upper yoke element 50 by means of the retaining element 30.

[0065] The upper yoke element 50 is not part of the contact arrangement 200, but is arranged independently of the contact arrangement 200 and thus independently of the lower yoke element 40 in the switching chamber 11. In particular, the upper yoke element 50 is arranged and fastened between the fixed contacts 2 relative to them. As shown in Fig. As can be seen in Figure 2A, the upper yoke element 50, as well as the fixed contacts 2, are preferably attached to the switching chamber 11, in particular to the switching chamber wall 12, which may, for example, be made of a ceramic material to ensure sufficient stability. For example, the upper yoke element 50 and the fixed contacts 2 may each be attached to the switching chamber by soldering. The upper yoke element 50 may have a soldering flange for this purpose. In particular, the upper yoke element 50 may be attached to an inner side of the switching chamber 11 by soldering. Alternatively, the upper yoke element 50 may also be attached to the switching chamber 11 by bonding, riveting, screwing, or crimping.

[0066] The retaining element 30 is attached to the axle 7. In the illustrated embodiment, the retaining element 30 comprises an electrically insulating plastic, in particular a plastic described above in the general section, wherein a portion of the axle 7 is formed with the material of the retaining element 30, as shown in Fig. 2A is recognizable. The axis 7 has an anchoring element in the form of grooves for locking the retaining element 30 and thus the contact arrangement 200. These grooves run completely around the axis 7 and the material of the retaining element 30 can engage in them. Alternatively, another fastening method is also possible, for example by means of rivets or screws.

[0067] The retaining element 30 has a base plate 31 which is attached to the axis 7. The retaining element 30 has, as shown in the following, a base plate 31. Fig. 2B and Fig. As indicated in Figure 2C, clamping elements 32 are provided for the movable mounting of the contact bridge 4. The retaining element 30 can particularly preferably be formed in one piece and be made of a material as described above in the general section. The contact bridge 4 is slidably mounted on the retaining element 30 by means of the clamping elements 32. In particular, the contact bridge 4 is slidably mounted on the retaining element along a direction of movement parallel to the axis 7. For guiding the contact bridge 4, the retaining element 30 has guide elements 36 and stops 37, which form the clamping elements 32. The guide elements 36 are designed as guide rails and allow movement of the contact bridge 4 along the desired direction of displacement, while the movement of the contact bridge 4 in other directions is restricted by the guide elements 36.To limit the displacement of the contact bridge 4, particularly along the direction of movement along the axis 7, the retaining element 30 has stops 37 arranged on one side of the guide elements 36 opposite the base plate 31. Specifically, two guide elements and one stop 37 each form a clamping element 32, which in each case forms an opening 38 with the base plate 31. As in . Fig. As shown in Figure 2B, each of the clamping elements 32 encompasses the contact bridge 4. In other words, the contact bridge 4 can protrude through the openings 38 and can therefore be guided within the openings 38 of the clamping elements 32.

[0068] The retaining element 30 can further be designed such that the stops 37, in an energized state of the switching device 100, project into a space between a fixed contact 2 and the upper yoke element 50, as shown in Fig. 2A is recognizable. This allows, for example, at least partial electrical insulation of the upper yoke element 50 from the fixed contacts 2.

[0069] The contact arrangement 200 further comprises a contact spring 34, which is arranged on the underside of the contact bridge 4 facing the base plate 31. In other words, the contact spring 34 is arranged between the contact bridge 4 and the base plate 31. The retaining element 30, and in particular the base plate 31 of the retaining element 30, has a spring retainer 39, which counteracts any displacement of the contact spring 34 on the retaining element 30. As shown, the spring retainer 39 can, for example, have or be formed from a pin that is surrounded by a portion of the contact spring 34.

[0070] The contact spring 34 is designed as a compression spring. As described above, the contact spring 34, in conjunction with an overstroke, can increase the contact pressure of the contact bridge 4 against the stationary contacts 2. Because the contact spring 34 is arranged between the contact bridge 4 and the base plate 31, it tends to push the contact bridge 4 and the base plate 31 apart, thereby pushing the contact bridge 4 towards the stationary contacts 2.

[0071] The upper yoke element 50 has a recess 52 on its underside facing the contact bridge 4. The recess 52 can be, as shown in the Fig. 2A, Fig. 2E and Fig. 2F is recognizable, in particular as a channel-like or groove-like recess. The contact bridge 4 can, in a switched-on state of the switching device 100, project at least partially into the recess 52. Furthermore, the contact bridge 4 can, as for example in Fig. As can be seen in a 2D view of the underside of the contact bridge 4 and the underside of the upper yoke element 50, the contact bridge 4 has a constriction 45, i.e., a rib-shaped area with a reduced width compared to the contact areas of the contact bridge 4. In an energized state of the switching device 100, the constriction 45 is at least partially located in the recess 52 of the upper yoke element 50. In particular, the recess 52 has a width that is greater than the width of the contact bridge 4, at least in the area of ​​the constriction 45. Furthermore, the recess 52 can have a depth that is less than, equal to, or substantially equal to the thickness of the contact bridge 4. During the transition from an off state to an on state of the switching device 100, the contact bridge 4 can retract into the recess 52 by the switching movement of the contact arrangement 200.The upper yoke element 50 can thus, in a switched-on state of the switching device 100, at least partially encompass the contact bridge 4 in the lateral direction 90, and in particular in the transverse direction 93. Fig. The position of the contact spring 34 is still indicated in 2D.

[0072] The contact bridge 4 can be particularly preferred, as especially in Fig. As can be seen, the upper yoke element 50 has a thickness greater than the depth of the recess 52. Therefore, in an energized state, the upper yoke element 50 can only partially engage the contact bridge 4. Consequently, in the energized state of the switching device 100, the contact bridge can partially protrude from the recess 52.

[0073] Furthermore, the contact bridge 4 can particularly preferably be spaced apart from the upper yoke element 50 in the switched-on state. As also in Fig. As can be seen from 2E, this means that the contact bridge has no mechanical contact with the upper yoke element 50 when switched on. Accordingly, an air gap can remain between the upper yoke element 50 and the contact bridge 4 even when switched on. Providing such a gap allows, for example, manufacturing tolerances to be accommodated. Furthermore, it prevents any undesirable consequences from potential erosion, i.e., the removal and uncontrolled deposition of material from the contacts 1, which can occur, for example, during the formation of switching arcs.

[0074] The upper yoke element 50, together with the contact bridge 4, forms an anti-levitation mechanism, the functioning of which, in conjunction with the Fig. Figure 3 illustrates this with a section of the switching device 100 in a sectional view with a section plane along the vertical direction 91 and transverse direction 92. The switching device 100 is shown here in an energized state, in which an electric current I flows through the contact bridge 4. Particularly in the case of a short-circuit current, as described above in the general section, a levitation force Flev can occur, which pushes the contact bridge 4 away from the stationary contacts. Without the effect described below, only the spring force of the contact spring counteracts the levitation force.

[0075] As in Fig. As indicated in Figure 3, in the switching device described here, a magnetic field with a magnetic flux MF is induced in the upper yoke element 50 when the switching device is switched on and a current flows through the contact bridge 4. Particularly in the case of a large current, such as a short-circuit current through the contact bridge 4, the magnetic field lines can concentrate on the upper surface of the upper yoke element 50. A greater thickness of the upper yoke element 50 above the contact bridge 4 can be advantageous in this respect. In particular, the upper yoke element 50 can preferably have a greater thickness than the contact bridge 4 in the vertical direction 91 above the contact bridge 4.

[0076] Since the field seeks the shortest path to minimize energy, the field is strongly compressed on the underside facing the contact bridge 4 and through the contact bridge 4, generating a reluctance force Frel on the contact bridge 4 that counteracts the levitation force and can accordingly also be called an anti-levitation force. Thus, a holding effect can be achieved by a flow of the magnetic field from the upper yoke element 50 through the contact bridge 4.

[0077] Modifications and further developments of the switching device are explained in conjunction with the following figures.

[0078] As in Fig. As indicated in 4A, the contact bridge 4 can also be formed without a constriction and thus, for example, have a simple cuboid shape. Furthermore, it is also possible, as shown in Fig. 4B indicates that one or more or all edges of the upper yoke element 50 and / or the contact bridge 4 are rounded or chamfered.

[0079] In conjunction with the figures described below, a further embodiment of the switching device 100 is explained. Fig. Figures 5A to 5D show various sections and parts of the switching device 100 according to the further embodiment. Fig. Figure 5A shows a sectional view of the switching device 100 with the contact arrangement 200, while the Fig. Figures 5B to 5D show different views of parts of the switching device 100 and, in particular, the contact arrangement 200. The following description of the switching device 100 applies equally to all Fig. 5A to 5D.

[0080] In Fig. 5A is compared to the view of the Fig. 1 additionally the housing 19 of the switching device 100 is shown, while in comparison to the Fig. 1. The return spring 10 for returning the magnetic drive 5 to the switched-off state is not shown for clarity. Fig. 5B shows coil connections 18 for controlling coil 8. Unless otherwise stated, these correspond to the connections shown in the Fig. The elements shown in 5A to 5D, in conjunction with the Fig. 1 and with the Fig. 2A to 3 explained elements.

[0081] The contact assembly 200 is arranged in the switching chamber 11, comprises the contact bridge 4, a retaining element 30 and a lower yoke element 40, and is attached to the axis 7. This allows the contact assembly 200 to be moved by the magnetic drive described above to perform the switching movements of the switching device 100.

[0082] Furthermore, the switching device 100, as in the exemplary embodiment of the Fig. 2A to 2F each have an upper yoke element 50. The lower yoke element 40 and the upper yoke element 50 can each be made of or consist of iron. In particular, the yoke elements 40 and 50 can each be made of or consist of pure iron. The contact bridge 4 is arranged between the lower yoke element 40 and the upper yoke element 50.

[0083] The upper yoke element 50 is, as in conjunction with the Fig. Described in sections 2A to 2F, it is not part of the contact arrangement 200, but is arranged and fastened independently of the contact arrangement 200 and thus independently of the lower yoke element 40 in the switching chamber 11, as described in connection with the Fig. 2A to 2F is explained.

[0084] The retaining element 30 is attached to the shaft 7. In the illustrated embodiment, the retaining element 30 comprises an electrically insulating plastic, in particular a plastic described above in the general section, wherein a portion of the shaft 7 is formed with the material of the retaining element 30. The shaft 7 has, for locking the retaining element 30 and thus the contact arrangement 200, as shown in Fig. As can be seen in Figure 5A, an anchoring element in the form of a groove is present, which runs completely around the axis 7 and into which the material of the retaining element 30 can engage. Alternatively, another fastening method is also possible, for example by means of rivets or screws.

[0085] The retaining element 30 has a base plate 31 which is attached to the axis 7. On the base plate 31, the retaining element 30 has clamping elements 32 for the movable mounting of the contact bridge 4 and the lower yoke element 40. The retaining element 30 can particularly preferably be formed in one piece and be made of a material as described above in the general section.

[0086] The contact bridge 4 and the lower yoke element 40 are each slidably mounted on the retaining element 30. Accordingly, the position of the lower yoke element 40 relative to the upper yoke element 50 can vary depending on the state of the switching device 100. Firstly, the relative position of the lower yoke element 40 to the upper yoke element 50 can change due to a displacement of the lower yoke element 40 on the retaining element 30 and thus within the contact arrangement 200. As described in more detail below, this can alter the air gap between the lower yoke element 40 and the upper yoke element 50, particularly when the switching device 100 is switched on. Secondly, the position of the lower yoke element 40 relative to the upper yoke element 50 can change due to a movement of the contact arrangement 200 within the switching chamber 11.Particularly preferably, the lower yoke element 40 is mounted on the retaining element 30 such that it is displaceable along a direction of movement parallel to the axis 7, and thus along the vertical direction 91. Furthermore, the contact bridge 4 is also displaceably mounted on the retaining element along a direction of movement parallel to the axis 7. This allows the contact bridge 7 and the lower yoke element 40, as well as the contact bridge 7 and the upper yoke element 50, to be displaceable relative to each other.

[0087] The lower yoke element 40 can at least be used in the Fig. The switching device 100 rests on the base plate 31 in the off state indicated by 5A to 5C. For secure positioning, the lower yoke element 40 can, for example, have edge grooves on the side facing the base plate 31, into which projections of the base plate 30 can engage.

[0088] To guide the contact bridge 4 and the lower yoke element 40, the retaining element 30 has guide elements 36 and stops 37. The guide elements 36 are designed as guide rails and allow movement of the contact bridge 4 and the lower yoke element 40 along the desired direction of displacement, while the movement of the contact bridge 4 and the lower yoke element 40 in other directions is restricted by the guide elements 36. To limit the displacement of the contact bridge 4 and the lower yoke element 40, particularly along the direction of movement along the axis 7, the retaining element 30 has stops 37 arranged on one side of the guide elements 36 opposite the base plate 31. In particular, two guide elements and one stop 37 each form a clamping element 32, which forms an opening 38 with the base plate 31. As shown in Fig. As shown in Figure 5C, each of the clamping elements 32 encompasses the contact bridge 4. In other words, the contact bridge 4 can project through the openings 38 and can thus be guided within the openings 38 of the clamping elements 32. In the illustrated embodiment, the lower yoke element 40 is guided between the clamping elements 32. Alternatively or additionally, the lower yoke element 40 can also be designed such that it projects through the openings 38 and is guided within the openings 38, and is thus encompassed by the clamping elements 32.

[0089] The retaining element 30 can further be designed such that the stops 37, in an energized state of the switching device 100, project into a space between a fixed contact 2 and the upper yoke element 50, as shown in Fig. 5B is recognizable. This allows, for example, at least partial electrical insulation of the upper yoke element 50 from the fixed contacts 2.

[0090] The contact arrangement 200 further comprises a contact spring 34, which is arranged on the underside of the contact bridge 4 facing the lower yoke element 40. In other words, the contact spring 34 is, compared to the embodiment of the Fig. The contact spring 34 is arranged between the contact bridge 4 and the lower yoke element 40. Contact spring 34 is designed as a compression spring. As described above, the contact spring 34, in conjunction with an overstroke, can increase the contact pressure of the contact bridge 4 against the stationary contacts 2. Because the contact spring 34 is arranged between the contact bridge 4 and the lower yoke element 40, it tends to push the contact bridge 4 and the lower yoke element 40 apart. The contact spring 34 thus generates a spring force that counteracts the approach of the lower yoke element 40 to the contact bridge 4. As shown, the contact spring 34 can be supported, in particular, directly on the underside of the contact bridge 4 and / or directly on the lower yoke element 40. The lower yoke element 40 has a recess 41 into which the contact spring 34 projects and by which its position can be fixed.

[0091] The upper yoke element 50 has a recess 52 on its underside facing the contact bridge 4. The recess 52 can, as shown, be designed in particular as a trough-like or groove-like recess. In an energized state of the switching device 100, the contact bridge 4 can project at least partially into the recess 52. Furthermore, the contact bridge 4 can, as shown in Fig. 5D in a view of the underside of the contact bridge 4 and the underside of the upper yoke element 50, as can already be seen in connection with the embodiment of the Fig. As explained in sections 2A to 2F, the contact bridge 4 has a constriction 45, i.e., a rib-shaped area with a reduced width compared to the contact areas of the contact bridge 4, wherein the constriction 45 is at least partially located in the recess 52 of the upper yoke element 50 when the switching device 100 is switched on. In particular, the geometric design of the contact bridge 4 and the upper yoke element 50 can be described as in conjunction with the Fig. 2A to 4B should be described.

[0092] Alternatively or additionally to the illustrated embodiment, the lower yoke element 40, which in the illustrated embodiment is plate-shaped, can, for example, have a recess corresponding to the recess 52, while the upper yoke element 50 can have a flat underside. Furthermore, it is also possible that both yoke elements 40, 50 each have a recess through which each of the yoke elements 40, 50, in a corresponding position relative to the contact bridge 4, can partially engage the contact bridge 4 from below or from above.

[0093] The contact arrangement 200, and in particular the lower yoke element 40 and the upper yoke element 50, form, in addition to the one in conjunction with the Fig. The effect described in point 3 involves another anti-levitation mechanism, the functioning of which is linked to the Fig. 6A to 6D based on sections of the switching device 100 in sectional views with section planes along the vertical direction 91 and the longitudinal direction 93 ( Fig. 6A, Fig. 6C) along the vertical direction 91 and transverse direction 92 ( Fig. 6B, Fig. 6D). The switching device 100 is shown here in an switched-on state, in which an electric current I flows through the contact bridge 4, as in the Fig. 6A and Fig. 6C is indicated.

[0094] In the switched-off state of the switching device 100, the moving parts of the switching device 100 are in the lower rest position, as previously described. Fig. Figure 5A shows the electrical contact between the fixed contacts 2 and the contact bridge 4. In this state, the electrical contact between the fixed contacts 2 and the contact bridge 4 is broken. The contact spring 34 pre-tensions the contact bridge 4 and the lower yoke element 40 and holds them in position within the cage of the retaining element 30 formed by the base plate 31 and the clamping elements 32. When the switching device 100 is switched on, a control current flows through the coil 8 of the magnetic drive, causing the magnetic core 6 to move upwards. This, in turn, causes the contact assembly 200, including the contact bridge 4, the retaining element 30, the contact spring 34, and the lower yoke element 40, to move upwards via the shaft 7, pressing the contact bridge 4 against the fixed contacts 2. The magnetic core 6, the shaft 7, the retaining element 30, the contact spring 34, and the lower yoke element 40 then continue to move upwards until the magnetic core abuts the yoke of the magnetic drive.This further compresses the contact spring 34 and ensures sufficient contact force between the contacts 1 to permanently carry the nominal current. This condition is the normal state of the switching device 100 when switched on and is described in the [document / section]. Fig. 6A and Fig. 6B shown.

[0095] The electric current I flowing through the contact bridge 4 induces a magnetic flux MF in the yoke elements 40, 50. This magnetization causes a reluctance force Frel, i.e., an attractive force, between the yoke elements 40, 50, which opposes the spring force Fs of the contact spring 34. The acting reluctance force Frel, i.e., the attractive force, is stronger the greater the electric current I flowing through the contact bridge 4. However, since the contact spring 34 tends to push the lower yoke element 40 away from the contact bridge 4 and thus also from the upper yoke element 50, the spring force Fs can be greater than the reluctance force Frel between the yoke elements 40, 50 at sufficiently small electric currents I. In this case, which represents normal operation, the moving parts remain in the position described in the Fig. 6A and Fig. Position shown in 6B.

[0096] An air gap L is present between the yoke elements 40, 50, which corresponds to a first distance L1 between the yoke elements 40, 50. The first distance L1 can particularly preferably be more than 1 mm and especially several millimeters, for example 3 mm or even 5 mm.

[0097] By appropriately selecting the spring constant of the contact spring 34, the geometric design and size of the yoke elements 40, 50, and the first distance L1, a current threshold for the electric current I can be set, up to which the current in the Fig. 6A and Fig. The state shown in Figure 6B is maintained, and the air gap L remains open as shown. The current threshold is preferably above the nominal current and can particularly preferably also be above smaller short-circuit currents. For example, the current threshold can be several kiloamperes, about 5 kA. In the low short-circuit current range below the current threshold, the levitation force Flev, which pushes the contact bridge 4 away from the stationary contacts 2, is small, so that the contact spring 34 alone can provide the force to hold the contact bridge 4 against the stationary contacts 2.

[0098] If the electric current I through the contact bridge 4 finally exceeds the current threshold, i.e., a state exists in which an increased short-circuit current flows through the contacts 1, the reluctance force Frel also increases proportionally with the electric current I and exceeds the spring force Fs. The lower yoke element 40 thus moves upwards, i.e., towards the upper yoke element 50. This reduces the size of the air gap L, which in turn further increases the magnetic flux MF. The reluctance force Frel therefore grows exponentially above the spring force Fs. The contact spring 34 is compressed further, preferably until the lower yoke element 40 rests on the underside of the contact bridge 4 or the underside of the upper yoke element 50. The air gap L corresponds, as in the Fig. 6C and Fig.As shown in Figure 6D, there is a smaller second distance L2 between the yoke elements 40, 50, which in this case can be minimal and even equal to 0 or nearly equal to 0. The contact force is now at its maximum and, in particular, so large that the reluctance force Frel continues to exceed the levitation force Flev, and the contact bridge 4 can continue to be pressed against the stationary contacts 2. Only above a maximum short-circuit current, which can be in the range of 16 kA or more, for example, are the yoke elements 40, 50 saturated by the magnetic flux MF, and the levitation force Flev can exceed the reluctance force Frel, causing the contact bridge 4 to lift off the stationary contacts 2.

[0099] The air gap L is thus variable, as described, depending on the electric current I flowing through the contact bridge 4, which also makes the holding force variable. It can be achieved that the additional holding force provided by the yoke elements 40, 50 is only engaged in the event of a short circuit above the current threshold, enabling the switching device 100 to withstand higher short-circuit currents compared to known solutions.

[0100] The features and embodiments described in connection with the figures can be combined with one another according to further embodiments, even if not all combinations are explicitly described. Furthermore, the embodiments described in connection with the figures can alternatively or additionally include further features as described in the general section.

[0101] The invention is not limited to the description provided by means of the exemplary embodiments. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes every combination of features in the claims, even if that feature or combination itself is not explicitly stated in the claims or exemplary embodiments. Reference symbol list 1 contact 2 fixed contacts 3 Insulator 4 Contact bridge 5 magnetic anchors 6 magnetic core 7-axis 8 coil 9 yoke 10 springs 11 Switching chamber 12 Switch chamber wall 13 Switch chamber floor 14 gas-tight area 15 Interior 16 permanent magnet 18 coil connections 19" enclosure 30 retaining element 31 Base plate 32 Clamping element 34 Contact spring 36 Guide element 37 attacks 38 Opening 39 spring holders 40 lower yoke element 41 In-depth study 45 Constriction 50 upper yoke element 51 Solder flange 52 In-depth study 60 air gap 90 lateral direction 91 vertical direction 92 longitudinal direction 93 transverse direction 100 switching device 200 contact arrangement I electric current Flev levitation power Fs spring force Frel reluctance force L1, L2 distance MF magnetic flux

Claims

[1] Switching device (100) comprising at least one fixed contact (2, 3), a contact bridge (4) and an upper yoke element (50) in a switching chamber (11), wherein the contact bridge (4) has a top surface with at least one contact area and a bottom surface opposite the top surface and is movable by means of a magnetic armature (5) with an axis (7), at least one contact area of ​​the contact bridge (4) in an switched-on state of the switching device (100) is in mechanical contact with the at least one fixed contact (2, 3), the axis (7) is located on the underside of the contact bridge (4), the upper yoke element (50) is arranged on the top of the contact bridge (4) and is attached to the switching chamber (11), the upper yoke element (50) has a recess (52) on one of the undersides facing the contact bridge (4) and the contact bridge (4) projects at least partially into the recess (52) when the switching device (100) is switched on. [2] Switching device (100) according to the previous claim, wherein the upper yoke element (50) is arranged laterally next to the at least one fixed contact (2, 3). [3] Switching device (100) according to one of the preceding claims, wherein the switching device (100) has two fixed contacts (2, 3) and the upper yoke element (50) is arranged between the two fixed contacts (2, 3). [4] Switching device (100) according to the previous claim, wherein the contact bridge (4) has a constriction (45) which, in an switched-on state of the switching device (100), is at least partially arranged in the recess (52) of the upper yoke element (50). [5] Switching device (100) according to one of the preceding claims, wherein the contact bridge (4) partially protrudes from the recess (52) when switched on. [6] Switching device (100) according to one of the preceding claims, wherein the contact bridge (4) has a thickness greater than the depth of the recess (52). [7] Switching device (100) according to one of the preceding claims, wherein the contact bridge (4) is spaced apart from the upper yoke element (50) when switched on. [8] Switching device (100) according to one of the preceding claims, wherein the upper yoke element (50) above the contact bridge (4) has a greater thickness than the contact bridge (4). [9] Switching device according to one of the preceding claims, wherein the upper yoke element (50) is attached to the switching chamber (11) by soldering, riveting, screwing, gluing or crimping. [10] Switching device (100) according to one of the preceding claims, wherein the switching device (100) has a contact arrangement (200) which is movable by means of the axis (7), wherein the contact arrangement (200) comprises a retaining element (30) and the contact bridge (4), wherein the retaining element (30) is attached to the axle (7) and wherein the contact bridge (4) is slidably mounted on the retaining element (30). [11] Switching device (100) according to the previous claim, wherein the retaining element (30) has at least one guide element (36) for guiding the contact bridge (4). [12] Switching device (100) according to one of the two preceding claims, wherein the retaining element (30) has at least one stop (37) to limit the displacement of the contact bridge (4). [13] Switching device (100) according to claims 11 and 12, wherein the retaining element (30) has at least one clamping element (32) which has at least one guide element (36) and at least one stop (37) and which at least partially surrounds the contact bridge (4). [14] Switching device (100) according to claim 12 or 13, wherein the at least one stop (37) projects into a space between the at least one fixed contact (2, 3) and the upper yoke element (50) when the switching device (100) is switched on. [15] Switching device (100) according to one of claims 10 to 14, wherein the contact arrangement (200) has a contact spring (34) which is arranged on an underside of the contact bridge (4) facing away from the upper yoke element (50) and presses the contact bridge (4) in the direction of the at least one stationary contact (2, 3). [16] Switching device (100) according to claim 15, wherein the contact spring (34) is supported directly on the underside of the contact bridge (4) and / or directly on the retaining element (30). [17] Switching device (100) according to claim 15 or 16, wherein the retaining element (30) has a spring retainer (39) which counteracts a displacement of the contact spring (34) on the retaining element (30) and the spring retainer (39) has a pin which is surrounded by a part of the contact spring (34). [18] Switching device (100) according to one of claims 10 to 14, wherein the contact arrangement (200) further comprises a lower yoke element (40) which is slidably mounted on the retaining element (30), and wherein an air gap (L) between the lower yoke element (40) and the upper yoke element (50) during the operation of the switching device (100) depends on an electric current (I) flowing through the contact bridge (4). [19] Switching device (100) according to claim 18, wherein the contact bridge (4) is arranged between the lower yoke element (40) and the upper yoke element (50). [20] Switching device (100) according to one of the two preceding claims, wherein a contact spring (34) is arranged between the contact bridge (4) and the lower yoke element (40), which pushes the contact bridge (4) and the lower yoke element (40) apart.

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