WO2021023325A1

WO2021023325A1 - Electrical switch for opening a current path

Info

Publication number: WO2021023325A1
Application number: PCT/DE2019/200095
Authority: WO
Inventors: Fabian Oehler; Michael Wortberg
Original assignee: Lisa Dräxlmaier GmbH
Priority date: 2019-08-05
Filing date: 2019-08-05
Publication date: 2021-02-11
Also published as: EP4010914A1

Abstract

The present invention relates to an electrical switch (100) for opening a current path (102). The switch (100) has a feed line (108) having an opening point (112) for opening the current path (102). At the opening point (112), a switching element (114) movable at least on one side is arranged in the feed line (108) in order to open and/or close the opening point (112). In a closed position, the switching element (114) has, on a movable side, a point of contact (118) with the feed line (108). The switch (100) also has a return line (110), which is electrically connected to the feed line (108) at an end of the feed line (108). A spaced arrangement of the feed line (108) and the return line (110) substantially antiparallel to each other, at least in the region of the opening point (112), is designed to at least partially compensate, by means of a Lorentz force (124) acting on the switching element (114) from the return line (110), a force which, while the current path (102) is carrying current, acts on the switching element (114) as a result of a local Lorentz force in the feed line (108) and in the switching element (114) and/or as a result of a constriction force (122) in the point of contact (118).

Description

ELECTRIC SWITCH FOR DISCONNECTING A POWER PATH

Technical area

The present invention relates to an electrical switch for disconnecting a current path, in particular in high-voltage current paths in a motor vehicle electrical system.

State of the art

The present invention is described below mainly in connection with switching elements for vehicle electrical systems. However, the invention can be used in any application in which electrical loads are switched.

If, for example, in the event of a short circuit in a drive system, a high current flow flows through a switch of a vehicle electrical system, a contact point can be opened unintentionally by a Lorentz force and / or tightness in the contact point caused by the current flow.

If the contact point is opened when there is a large flow of current, a switching arc occurs at a separation point between the two previously connected ends of the switch. The switching arc releases a large amount of energy that can damage the switch.

In order to prevent such damage, it should at best be avoided that a switch operated with a high current flow opens unintentionally. In addition, the aim should be that the time in which the switching arc burns can be reduced, for example by making a voltage drop in the switching arc greater than the electrical voltage available between the ends. The voltage drop can for example, can be increased by extending a length of the switching arc. This can be achieved, for example, via an air flow or gas flow that deflects the switching arc. This extends the switching arc and increases the voltage drop in the switching arc so much that the switching arc is extinguished.

Description of the invention

One object of the invention is to provide a reliably switching electrical switch for disconnecting a current path using means that are as simple as possible in terms of construction.

The object is achieved by the subject matter of the independent claim. Advantageous developments of the invention are given in the dependent claims, the description and the accompanying figures.

An electrical switch for disconnecting a current path is presented, the switch having an outgoing line with a disconnection point for disconnecting the current path, an at least one-sided movable switching element for opening and / or closing the disconnection point in the outgoing line being arranged at the disconnection point Switching element has a contact point for the outgoing line in a closed position on a movable side, the switch also having a return line connected to the outgoing line in an electrically conductive manner at one end of the outgoing line, with an essentially anti-parallel spaced arrangement of outgoing line and return line at least in the area of the separation point is designed for this purpose, a force acting on the switching element when the current path is carrying current due to a local Lorentz force in the forward line and the switching element and / or a tight force in the contact point by a Lorentz force acting on the switching element from the return line at least partially to compensate.

A current path can be understood to be a continuously electrically conductive path between a current source and a consumer. The power source can be, for example, a traction battery of an electric vehicle. The consumer can for example, a drive motor of the electric vehicle. The current path can be opened and interrupted or disconnected at a switch. The switch can be integrated into the current path using electrical interfaces. The interfaces can be referred to as terminals. Electrical conductors with a large cross-section can be connected to the terminals. The current path in the switch can be formed by busbars. Busbars can be massive strips of electrically conductive material. A feed line can lead from an input interface of the switch into a housing of the switch. A return line can lead from the housing of the switch to an output interface of the switch. At an end of the outgoing line opposite the input interface, the outgoing line can be connected to the return line in an electrically conductive manner. The return line can run essentially anti-parallel to the feed line back to the output interface.

When a current flows through the forward line and the return line, the current in the forward line and the return line flows in opposite or anti-parallel directions. Electromagnetic forces caused by the current flow, in particular forces acting on the switching element, such as the Lorentz force and / or Holm ^'s narrow force, are essentially canceled out due to the opposing causative current flow.

A separation point can be a point on the outgoing line provided for separating the current path. The return line can run parallel to the outgoing line in the switch housing in the area of the separation point. The return line can be arranged at a constant distance from the outgoing line. The distance between the forward line and the return line influences the compensating Lorentz force. The distance can be selected according to an expected current intensity on the current path.

The switch can be designed to be opened and closed several times. The switching element can be designed to open and / or close the separation point. The switch can have an actuator for driving the switching element. The switching element can be designed as a switching bridge that is movable on both sides. In this case, the switching element can extend parallel to the return line and can be moved in a direction transverse to the return line towards the forward line or away from the forward line. Both ends of the switching element can be moved, preferably in a direction perpendicular to the direction of extent of the Forwarding. Alternatively, the switching element can be firmly connected to the outgoing line on one side as a switching tongue. A second side of the switch tongue can be movable. The switching element can be connected to the feed line via a joint. The switching element can also be a movable end of the feed line.

The switching element can be moved between a closed position and an open position. In the closed position, the current path is closed at the contact point. In the open position, the current path is separated. In the closed position, the movable end of the switching element can rest laterally on the end of the outgoing line.

A length of the switching element in the direction of extent of the switching element and a distance between the switching element and the return line in a direction perpendicular to the direction of extent of the switching element can be dimensioned in such a way that the force acting on the switching element at the contact point due to the local Lorentz force and / or the narrow force through the Lorentz force caused by the current-carrying current path in the return line is at least 50% compensated for at a current intensity flowing through the current-carrying current path for which the switch is designed. Alternatively, the acting force can be fully compensated for at least 70%, at least 90% or even overcompensated.

Since the forces acting as levitation force, ie lifting on the switching element, such as the local Lorentz force and / or the Holm's narrow force, are at least to a significant extent compensated for by the Lorentz force generated with the help of the return line, there can be a risk that the switch will break at high currents unwanted opens and may be damaged by the formation of arcs.

The switching element can releasably rest against the outgoing line at the contact point on a side directed towards the return line. Due to the contact on the side facing the return line, the switching element can be pressed against the forward line by the Lorentz force acting on the switching element from the return line. Thus, the tight force or the local Lorentz force between the forward line and the switching element and the Lorentz force acting from the return line on the switching element act in opposite directions. The switching element can be movable into an intermediate space between the forward line and the return line to open the separation point. By opening into the gap, the switching element can be pressed against the outgoing line by the Lorentz force of the return line. The Lorentz force of the return line can thus compensate for the local Lorentz force and / or the tightness force.

The switch can have an actuator for bringing the switching element closer to and / or moving the switching element away from the contact point. In other words, the actuator can actively move the switching element between the open position and the closed position. A spring force stored in a spring accumulator of the actuator can be used to bring it closer or to move it away. The actuator can act against the spring force to move away or bring it closer. The switching element can itself act as a spring element that keeps the contact point closed or keeps it open. When the switching element is moved out of a rest position, the switching element can be elastically deformed.

The switching element can be designed as a switching bridge that is movable on both sides. The switching bridge can be aligned essentially parallel to the return line. The switching bridge can each have a contact point in the area of opposite ends. As a result of the essentially parallel alignment, the Lorentz force from the return line can act essentially completely on the switching element.

The switch can have an extinguishing device for extinguishing the switching arc resulting when the current-carrying separation point is cut. The extinguishing device can have a fuse element that is currentless during normal operation in a secondary path to the current path. The fuse element can be connected between a connection to a first side of the separation point and a secondary electrode of the secondary path. The secondary electrode can be arranged in the area of a second side of the separation point and be electrically insulated from the current path during normal operation. The secondary path can have a lower electrical resistance than the switching arc. The secondary electrode can be arranged in an area ionized by the switching arc. This allows the electrical current flow to commutate to the secondary electrode and flow away through the fuse element to the other side of the separation point. The fuse element can respond when the current flow is greater than a trigger value of the fuse element. The fuse element can be a fuse, for example. If the trigger value is exceeded, an arc ignites in the fuse, which is extinguished by melting sand in the fuse. Until the fuse element trips, the previous path of the switching arc is deionized again. So the switching arc cannot re-ignite.

The secondary electrode can be connected to at least one prong of an extinguishing comb arranged adjacent to the separation point. The at least two prongs of the extinguishing comb can be aligned essentially parallel to one another, be electrically separated from one another and arranged distributed over an opening width of the separating point. A extinguishing comb can have several prongs. The tines can be of different lengths. For example, the outer prongs of the extinguishing comb can be longer than the inner prongs of the extinguishing comb. The switching arc can jump over to the extinguishing comb because the path over the extinguishing comb has a lower electrical resistance than the original switching arc. The switching arc can be divided into several partial arcs in the extinguishing comb. The partial arcs can wander into the extinguishing comb. The secondary electrode can in particular be connected to a central prong of the extinguishing comb. The middle prong can be the shortest prong. The secondary electrode can provide a path for the current flow through the switching arc, which path has a lower resistance than a path past the secondary electrode or via the remaining prongs. The current flow follows the path of least resistance. When the current flow through the secondary path has been established, the cut off partial arcs are extinguished. The fuse element then completely interrupts the flow of current in the secondary path.

The prongs of the extinguishing comb can be designed as plates aligned essentially parallel to one another. A front edge of the plates can be arranged at a distance from the current path in the region of the separation point. The leading edge can essentially be aligned parallel to the current path. Plate-shaped prongs allow the partial arcs to wander over a surface of the plates and move away from one another. This makes it more difficult for extinguished partial arcs to re-ignite.

The switch can have at least one blow magnet. The blow magnet can be arranged adjacent to the separation point. The blow magnet can be designed to deflect the switching arc out of the separation point. A blow magnet can be a Be permanent magnet or an electromagnet. The blow magnet can be divided into several partial magnets. Partial magnets can mutually reinforce and / or homogenize their magnetic fields. The blow magnet can be aligned such that its magnetic field is essentially homogeneous in the area of the separation point. The magnetic field deflects the charge carriers moved by the current flow through the switching arc and the ionized particles in the area of the switching arc to the side. The deflection increases the length of the switching arc and thus increases the voltage drop in the switching arc. The blow magnet can deflect the switching arc in the direction of the secondary electrode. When using a blow magnet, a field strength of the magnetic field in the area of the switching element can be taken into account when determining the distance between the forward line and the return line.

The switch can have a movable, electrically insulating element that can be pushed into the opened separation point and an actuator for moving the element. The element can be a shaped piece which has cutouts for the components of the separation point.

The element can thus essentially enclose the components. By enclosing the distance to be bridged by the switching arc is significantly increased. This prevents a new switching arc from being ignited again. In addition, the components of the separation point are fixed in the cutouts, so that the open state of the separation point is safely retained even in the event of vibrations.

Brief description of the figures

An advantageous exemplary embodiment of the invention is explained below with reference to the accompanying figures. Show it:

1 shows an illustration of a switch according to an exemplary embodiment;

Figs. 2a to 2c representations of a switch with an insertable element according to an embodiment;

3 shows an illustration of a switch with an extinguishing device according to an embodiment; Figs. 4a and 4b representations of extinguishing a switching arc on a switch according to an embodiment;

5 shows an illustration of a switch with a cutting wedge and a quenching device; and

Figs. 6a and 6b representations of extinguishing a switching arc on a switch with a cutting wedge.

The figures are merely schematic representations and serve only to explain the invention. Identical or identically acting elements are provided with the same reference symbols throughout.

Detailed description

For easier understanding, the reference numerals for FIGS. 1-6 are retained as reference in the following description.

1 shows an illustration of a switch 100 according to an exemplary embodiment. The switch 100 is designed to repeatedly disconnect and close a current path 102. The switch is designed for switching high-voltage motor vehicles with correspondingly high electrical current flows and accordingly has large cable cross-sections made of electrically conductive material, adapted material thicknesses of electrically insulating material and the required air and creepage distances. Vehicle high-voltage voltage can be up to one kilovolt. For example, the voltage in the high-voltage vehicle electrical system can be 400 to 600V or 800 to 1000V. High currents can flow, especially in the event of a short circuit. For example, the maximum short-circuit current can be up to 15kA. Depending on the internal resistance of the battery, the short-circuit current can be up to 30kA.

The switch 100 has a first terminal 104 as an input interface and a second terminal 106 as an output interface. The terminals 104, 106 are on the same Side of the switch 100 arranged, since the switch 100 has a forward line 108 from the first terminal 104 into the switch 100 and a return line 110 arranged parallel thereto from the switch 100 back to the second terminal 106. The forward line 108 and the return line 110 thus run through the switch 100 at a constant distance within a narrow tolerance range. The forward line 108 and the return line 110 are connected to one another in an electrically conductive manner on a side facing away from the terminals 104, 106.

The terminals 104, 106 are designed here as extensions of the outgoing line 108 and the return line 110, respectively. The outgoing line 108, the return line 110 and the connection between the two are designed as massive busbars made of electrically conductive solid material, such as copper. The terminals 104, 106 each have an opening for a connecting means for connecting the switch 100 to the current path.

A separation point 112 of the switch 100 is arranged in the outgoing line 108. Here the separation point 112 is formed by a switching element 114 that is movable on both sides. The switching element 114 is mechanically coupled to an actuator 116. The switching element 114 is designed as a solid switching bridge and has contact surfaces 118 at two opposite end regions, with which the switching element rests against the free ends of the outgoing line 108. The switching bridge has essentially the same line cross section as the outgoing line 108.

The switching element 114 is arranged here in an intermediate space 120 between the forward line 108 and the return line 110. To separate the separation point 112, the switching element 114 is moved further away from the feed line 108 into the space 120. The contact surfaces 118 are designed as contact plates in order to achieve increased surface pressure for a requirement-based electrical contact or low transition resistance between the switching element 114 and the outgoing line 108 when the switch 100 is closed.

When the switch 100 is closed, the current path 102 is closed and current can flow through the switch 100. The current flow results in a local Lorentz force and / or tight force 122 at the contact points 118, which the switching element 114 wants to lift off the forward line 108. By the current flowing in the opposite direction the parallel return line 110 also generates a Lorentz force 124 which is directed opposite to the Lorentz force and / or narrow force 122. The Lorentz force 124 and the Lorentz force and / or narrow force 122 essentially cancel each other out. The Lorentz force 124 is essentially dependent on the current strength in the return line 110 and the distance between the forward line 108 and the return line 110.

In one embodiment, two blow magnets 126 are arranged in the space 120. The blow magnets 126 are arranged to the right and left of the switching element 114.

The blow magnets 126 are aligned in such a way that their magnetic fields reinforce one another in the area of the switching element 114. The north pole of one blow magnet 126 points to the south pole of the other blow magnet 126. In addition, this results in a homogeneous magnetic field between the blow magnets 126.

Figs. 2a to 2c show representations of a switch 100 with an insertable element 200 according to an exemplary embodiment. The switch essentially corresponds to the switch in FIG. 1. The illustration in FIG. 2a essentially corresponds to the illustration in FIG. 1. In contrast to this, the switch 100 is shown with the separation point 112 open.

The switching element 114 has been pulled into the intermediate space 128 by the actuator 116. The contact points 118 are non-contact. The element 200 has been pushed into the opened separation point 112 from the side by a further actuator (not shown). The element 200 is made of an electrically insulating material, for example a ceramic material. In the illustrated embodiment, no blow magnet is used so as not to influence the compensating Lorentz force.

In Fig. 2b, the element 200 is shown with cutouts 202 for the ends of the feed line 108 and the switching element 114. The contact plates of the contact points 118 are also shown in the recesses 202. In FIG. 2a the ends and the switching member 114 are arranged in the recesses 202. A relative position of the switching element 114 to the outgoing line 108 is secured by the cutouts and an inadvertent closing of the separation point 112 by the element 200 arranged in the separation point 112 is excluded. The element 200 ensures that the switch 100 remains open even if the switch 100 is exposed to strong vibrations and / or the actuator 116 fails. The further actuator 204 is shown in FIG. 2c. Here the further actuator 204 is just about to push the element 200 into the opened separation point 112.

In other words, FIGS. 1 to 2 show a switch with compensation for the levitation force. It is about the interaction between high-voltage contactor and high-voltage fuse in high-voltage switch boxes of electric and hybrid vehicles (BEV & PHEV).

In the case of large short-circuit currents, the contactor should remain closed and a fuse, in particular connected in series with the contactor, should take over the interruption of the current. If, however, due to the electromagnetic forces prevailing in the contactor, in particular the Lorentz force and Holm's narrow force, the switching contacts open unintentionally before the fuse trips, the contactor can explode. Furthermore, the electric arcs that then arise in the contactor limit the short-circuit current due to their voltage drop, which delays the triggering of the fuse. The fuse trips when its melting integral (I ² t value) is reached.

The geometry of the current conduction presented here leads to a compensation of the Lorentz and narrow forces. As a result, only the contact force generated and desired by a spring now acts. In addition, the resulting arc can be extinguished by inserting an electrical insulator made of ceramic, for example.

Blow magnets can be used to extinguish the arc. These generate a magnetic field which is oriented transversely to the direction of movement of the electrons in the arcs, whereby the electrons are deflected onto a circular path. This increases the arc path, which is proportional to the arc voltage. Blow magnets can generate an additional Lorentz force that acts on the switching bridge, which reduces the levitation limit at which the switching contacts are lifted.

The approach presented here results in an increase in system security, since the contactor remains in a closed state, does not explode, but welds to the maximum. A series-connected fuse with a larger fuse rating can be used, as the robustness of the contactor is increased. In this way, the charging currents, which will very likely continue to rise in the future, can be managed. The switch presented here has significantly increased levitation limits compared to known contactors, without any significant enlargement of the component. For example, more than eight kiloamps can be reached as the levitation limit.

In the switch presented here, the busbars are arranged in such a way that the Lorentz force on the switching bridge, caused by the additional lower busbar, presses it down. For this purpose, the lower busbar is precisely spaced so that the electromagnetic forces compensate each other. The compensating Lorentz force can through

F _L = B (l, d) x L ^* I with the current I, the vector length of the switching bridge L and the magnetic flux density B (l, d) at the point of the switching bridge, which depends on the current and the distance d to the lower Busbar is to be described.

With a suitable choice of parameters d and L, the external Lorentz force can be set in such a way that it compensates for the local Lorentz force and narrow force at the two contact points.

Magnets can be used to extinguish the switching arc that occurs when the contacts are opened under power. Due to their magnetic field direction, which is transverse to the direction of movement of the charge carriers, these force the electrons onto a circular path. This increases the arc length until the arc finally breaks off. However, the magnetic field of the magnets also penetrates the switching bridge and thus strengthens the repulsive Lorentz force.

In order to avoid this, the switch in FIG. 2 does not have any blow magnets. The arc is extinguished by inserting a body made of an electrical insulator (e.g. ceramic). This penetrates the contact point and then greatly extends the arc until it breaks off.

3 shows an illustration of a switch 100 with an extinguishing device 300 according to an exemplary embodiment. The switch 100 essentially corresponds to the switch in FIGS. 1 and 2. In addition, the switch 100, as the quenching device 300, has a secondary path 302 to the current path 102 that is currentless in normal operation. By doing A securing element 304 is arranged in the secondary path 302. The fuse element 304 is a fuse here. A first end of the fuse element 304 is electrically conductively connected to the current path 102 on a first side of the separation point 112. A second end of the fuse element 304 is electrically conductively connected to a secondary electrode 306. The secondary electrode 306 is arranged to be electrically insulated from the current path 102 during normal operation. Here the secondary electrode 306 is arranged laterally next to the separation point 112.

In one exemplary embodiment, the secondary electrode 306 is connected to a central prong 308 of an extinguishing comb 310. The extinguishing comb 310 here has five prongs 308 which are arranged distributed over an opening width of the separation point 112. The prongs 308 are electrically isolated from one another. The outer tines 308 of the extinguishing comb 310 are longer than the inner tines 308 of the extinguishing comb 310. The middle tine 308 is the shortest tine 308 and is thus furthest away from the separating point 112.

In one embodiment, the secondary electrode 306 is connected to the return line 110 via the fuse element 304 and thus shortens the secondary path 302. Here, a single blow magnet 126 is arranged laterally next to the separation point 112. As a result, field lines of the magnetic field run in an arc through the separation point 112. The blow magnet 126 is, however, significantly longer than the switching element 114, so that the magnetic field in the region of the separation point 112 is essentially homogeneous.

In one embodiment, the prongs 308 of the extinguishing comb 310 are designed as plates. The plates are aligned essentially parallel to one another. Each of the plates is at a substantially constant distance from the current path 102.

In other words, the switch 100 shown here has an outgoing line 108 with a separating point 112 for separating a current path 102, a switching element 114, which is movable at least on one side, for opening and / or closing the separating point 112 in the outgoing line 108 is arranged at the separating point 112, with the switching element 114 in a closed position on a movable side has a contact point 118 to the outgoing line 108, the switch 100 having a quenching device 300 for extinguishing a switching arc resulting when the current-carrying isolating point 112 is disconnected, the quenching device 300 having a fuse element 304 which is currentless in normal operation a secondary path 302 to the current path 102, the fuse element 304 being connected between a connection to a first side of the separation point 112 and a secondary electrode 306 of the secondary path 302, the secondary electrode 306 being arranged in the area of a second side of the separation point 112 and in regular operation is electrically isolated from the current path 102, the switch 100 further having an extinguishing comb with at least two prongs 308 arranged adjacent to the separation point 112, the prongs 308 possibly being aligned substantially parallel to one another, electrically separated from one another and over an opening width of the separation point 112 are arranged distributed, the secondary electrode 306 being connected to at least one of the prongs 308.

Figs. 4a and 4b show representations of extinguishing a switching arc 400 on a switch 100 according to an embodiment. The switch 100 corresponds essentially to the switch in FIG. 3. In FIG. 4a, the switch 100 has just been opened using the actuator, not shown. In the contact point 118, the switching arc 400 has ignited between the feed line 108 and the switching element 114. The blowing magnet 126 has blown the switching arc 400 into the extinguishing comb 310. As a result, the switching arc 400 has been divided into five partial arcs 402. The partial arcs 402 run from the feed line 108 to the nearest prong 308, from there from prong 308 to prong 308, skipping the shortest, middle prong 308, and from the last prong 308 to the switching element 114. In each partial arc 402, voltage falls and weakens the switching arc 400.

In FIG. 4b, the switching arc 400 has jumped to the middle prong 308 and thus to the secondary electrode 306, since the electrical potential of the return line 110 is directly applied to the secondary electrode 306. The partial arcs 402 to the further prongs 308 have gone out. As a result of the flashover on the secondary electrode 306, the current flow in the secondary path 302 exceeds a response threshold of the fuse element 304 and it trips. The current flow is interrupted by the triggered fuse element 304, the switching arc 400 extinguishes and the separation point 112 is separated.

In other words, FIGS. 3 and 4 show a switch with an arc switch in an extinguishing comb. The contactor presented here can switch off larger short-circuit currents. The arc switch is used to extinguish the arc. The arc switch is integrated in a so-called extinguishing comb or arc comb. The principle of such an extinguishing comb is based on the effect of lengthening the arc path and the initial voltage drop of an arc of approx. 10 to 20 V. The arc is driven into the extinguishing comb by an air flow or magnets. The secondary electrode of the arc switch is located in the rear part of the extinguishing comb. This can also be designed as a connection to a lamella of the comb. Due to the lower resistance of the secondary path compared to the disturbed primary path over the entire extinguishing comb, a large part of the current then flows over this path. In the fuse element of the arc switch, the current melts a narrow point, creating an arc in this element. This is also deleted by the security element, which can be filled with sand, for example. The path is thus interrupted and galvanically isolated.

In one embodiment, the switch has the special busbar geometry shown in FIG. 1 in order to compensate for the levitation effect. Since blow magnets are required for the function of the extinguishing comb, the electromagnetic forces cannot be completely eliminated, but they can be greatly reduced. This increases the levitation limit significantly.

The approach presented here increases system security, as the contactor can separate larger currents through the extinguishing comb. This eliminates the unsafe condition that can arise from the interaction of the contactor and the fuse connected in series. The reason for this is that the tripping time of the fuse is determined by the characteristic I ² t value. The lower the current, the longer the fuse needs to reach its melting integral. Since the heating of the constriction is also less adiabatic with lower currents, the tripping time is also extended. If the switching limit of the contactor can now be increased, the tripping time of the fuse is significantly reduced.

In Fig. 3 the contactor is shown with the arc switch integrated in an extinguishing comb. A magnet is arranged on the side of the switching chamber. This magnet can also be interrupted, as in FIG. 1, so that the arrangement contains two magnets. The blow magnet generates a magnetic field in the switching chamber, which is aligned transversely to the direction of flow of the electrons in the arc, whereby they are deflected and in Be driven towards the extinguishing comb. If the blow magnets are arranged to the right and left of the switching chamber, a very homogeneous magnetic field is created inside the switching chamber. The blow magnets could also be designed as electromagnets.

The deflection of the electrons on a circular path can be clearly seen in FIG. The action of the comb divides the arc into several parts. Each part results in an initial arc voltage of 10 to 20 V depending on the material of the comb, so that the arc voltage is increased in stages. This is sufficient for normal overcurrents to extinguish the arc. The arc breaks shortly after entering the extinguishing comb and the current is interrupted. The arc switch remains inactive in this case.

In the event of very high short-circuit currents to be separated, the "cloud" of ionized gas in the arc comb reaches the secondary electrode of the arc switch, which is connected to the other potential via an overcurrent protection device, so that there is a potential difference between the arc base on the contactor and the secondary electrode. The arc commutates to this secondary electrode, so that the portion of the primary arc to the switching bridge is extinguished. If the melting integral of the overcurrent protection device / fuse element is reached, an arc ignites in it, which interrupts the current path.

In one embodiment, the contactor with the arc switch in the extinguishing comb is combined with the principle of compensation of the levitation force shown in FIG. 1. The additional magnetic field of the permanent magnets / blow magnets influences the Lorentz force independently of the current. The busbars are arranged so that the Lorentz force caused by the conductor loop has a closing effect on the switching bridge. The switching bridge moves in the magnetic field of the lower busbar B (l, d) and in the magnetic field of the blow magnets BL. The following applies to the resulting Lorentz force:

F _L = B (l, d) x L ^* I + B _L x L ^* I with the current I and the length of the switching bridge L (vectorial). L is defined in such a way that it is positive when the current flows in the L direction. B _x x L describes the cross product of the respective magnetic field component with the length of the contact bridge (vectorial). By suitably selecting the parameters d and L, the external Lorentz force can be set in such a way that it largely compensates for the local Lorentz force and narrow force at the two contact points. Due to the effect of the blow magnets, the compensating force is reduced or increased depending on the direction of the current. Since the magnetic field of the blowing magnets does not depend on the current I, a balance of the repulsive and pressing electromagnetic forces acting on the switching bridge can only be achieved for a certain current value with this arrangement.

FIG. 5 shows an illustration of a switch 100 with a cutting wedge 500 and a quenching device 300. The switch 100 essentially corresponds to the switch in FIG. 3. In contrast to this, the switch 100 can and is only used once for safe separation of the current path 102 destroyed in a controlled manner. As a result, the switch 100 has no switching element at the separation point 112. Instead of the switching element, a solid electrical conductor 502 runs through the cutting point 112. The cutting wedge 500 is aligned with the cutting point 112. To drive the cutting wedge 500, the switch 100 also has the actuator 116. In contrast to FIG. 1, the actuator 116 is here an electrically ignitable detonator. Because the ignition capsule is used as actuator 116, switch 100 can be referred to as a pyrofuse and used as a controllable overcurrent protection device.

As in FIG. 3, the extinguishing device 300 has the secondary path 302 that is currentless in normal operation. The fuse element 304 and the secondary electrode 306 are likewise arranged in the secondary path 302. The secondary path 302 is connected to the current path 102 on the first side of the separation point 112. The secondary electrode 306 is arranged in the region of the opposite second side of the separation point 112, but is arranged at a distance from the current path 102.

An abutment 504 for the cutting wedge 500 is arranged between the current path 102 and the secondary path 302. The abutment 504 is arranged behind the cutting point 112 as viewed from the cutting wedge 500 and is designed to catch the cutting wedge 500 after the cutting point 112 has been cut. When caught, the cutting wedge 500 can penetrate into the abutment 504 and get stuck.

The conductor 502 has a taper 506 at the separation point 112. The taper is a predetermined breaking point of the conductor 502 and has a reduced line cross-section on. However, the line cross-section is still sufficient to transfer the electrical load as required.

The switch 100 has no return line, since in the case of the solid continuous conductor 502 no compensation for the Lorentz force or the narrow force is required or such forces do not occur or only occur negligibly with the specified switch geometry.

In other words, the switch 100 shown here has an electrical conductor 502 that can be destroyed at the separation point 112 for separating a current path 102 at a separation point 112. A cutting wedge 500 that can be driven by an actuator 116 is aligned with the severing point 112. The switch 100 has an extinguishing device 300 for extinguishing a switching arc resulting when the current-carrying separation point 112 is cut. The quenching device 300 has a fuse element 304 that is currentless during normal operation in a secondary path 302 to the current path 102. The fuse element 304 is connected between a connection to a first side of the separation point 112 and a secondary electrode 306 of the secondary path 302. The secondary electrode 306 is arranged in the region of a second side of the separating point 112 and is electrically isolated from the current path 102 during regular operation.

Figs. 6a and 6b show illustrations of the extinguishing of a switching arc 400 on a switch 100. The switch 100 corresponds essentially to the switch in FIG. 5. In FIG. 6a, the detonator has been ignited by an electrical signal from a control device and has the cutting wedge 500 on the separation point 112 driven through the conductor 502. Due to the sudden separation of the current path, the switching arc 400 is drawn up in the separation point 112. Here the switching arc 400 is still burning through a remaining gap 600 between the cutting wedge 500 and the abutment 504, since the cutting wedge 500 has not yet reached the abutment 504 on its trajectory.

In FIG. 6 b, the cutting wedge 500 has reached the abutment 504 and has penetrated into the abutment 504. The cutting wedge 500 is stuck in the abutment 504. As a result, the gap has closed and the switching arc 400 has commutated to the secondary electrode 306. An electrical current flow now flows through the secondary path 302 of the extinguishing device 300. The current flow is greater than a trigger value of the Fuse element 304 and the fuse element responds. Here, the fuse element 304 is a fuse. When the trigger value is exceeded, another arc ignites in the fuse and destroys the electrical conductor leading through the fuse. The arc melts a sand filling of the fuse at least partially. The molten sand extinguishes the arc, thereby breaking the secondary path 302.

In other words, FIGS. 5 and 6 show a pyrofuse with an arc switch.

A fuse can be connected in parallel to a pyrofuse. Due to the different contact resistances of the pyrofuse and the fuse, the pyrofuse takes over a large part of the traction or charging current. This reduces the aging of the fuse. Since the fuse carries currents during operation, its nominal value must not fall below a certain value, otherwise aging will increase again.

The pyrofuse presented here includes an "arc switch". The pyrofuse's explosive charge is ignited by a trigger signal in the event of an overcurrent. Subsequently, a separating wedge, an extinguishing agent and / or a gas is used to break through a busbar with a predetermined breaking point. This creates an arc. As the distance between the two parts of the busbar increases, the arc lengthens, which increases the arc voltage. An extinguishing agent can help cool the arc, which also increases the arc voltage. If the voltage reaches the value of the external supply voltage, the break-off condition for the arc is given and it breaks off. For larger currents, an ever greater arc length is required in order to build up the required arc voltage.

The secondary electrode of the arc switch with a fuse element is placed below the busbar. It is arranged in such a way that part of the conductor rail approaches the secondary electrode when it is disconnected. Due to the arc plasma and the ionized gases, the secondary arc ignites at a certain point in time. Due to the smaller distance between a part of the busbar and the secondary electrode compared to the second part of the busbar, a large part of the current now flows via the secondary path. The primary arc can be extinguished by the pyrofuse. The current melts a constriction in the fuse element, creating an arc arises. This is also deleted by the security element, which can be filled with sand, for example. The path is interrupted and galvanically isolated.

The fuse is never loaded with current during normal operation of the vehicle. This completely eliminates electricity-related aging mechanisms. The nominal value of the fuse can be reduced significantly, which in turn also significantly reduces the disconnection time. The pyrofuse can be made smaller because the pyrofuse is used to ensure a quick release. Most of the switching energy is absorbed in the fuse element.

The pyrofuse in FIG. 5 has a detonator located in the upper part, which can be ignited by a control, for example via a current pulse. In the variant shown here with a wedge instead of extinguishing agent or gas, there is a separating wedge under the capsule, which can interrupt a busbar at a predetermined point. During the shutdown process shown in FIG. 6 after the detonator has been ignited and the busbar is separated by the wedge, an arc is ignited which the wedge drives in front of it. In the other embodiments, the arc is extended in the direction of the secondary electrode by the extinguishing agent or the pressure of the gas.

The ionized gas of the arc and the decreasing distance between the first part of the busbar and the secondary electrode cause the secondary arc to ignite. The busbar can also touch the secondary electrode. Since the current can now flow via the secondary path with less resistance, a large part now flows via this path. The primary arc is also extinguished because of the action of the wedge.

When the melting integral of the overcurrent protection device is reached, another arc ignites in the component. Due to the structural design of the fuse element, a long arc is quickly drawn up, in which the essential energy conversion, which is essential for separating the short-circuit current, takes place. With an instantaneous output of up to approx. 1.5 MW, the sand filling melts locally. The melted sand extinguishes the arc, which interrupts the flow of current. Adequate design of the time sequence during the separation process ensures that the wedge has already moved so far during the interruption of the current flow in the fuse element that the arc cannot “jump” back onto the primary path. The arc goes out. The current flow is then complete interrupted and the path is galvanically separated. The principle of redirecting the arc to a secondary path with energy guidance is called the arc switch.

Since the devices and methods described in detail above are exemplary embodiments, they can usually be modified to a large extent by a person skilled in the art without departing from the scope of the invention. In particular, the mechanical arrangements and the proportions of the individual elements to one another are selected merely as examples.

REFERENCE LIST

100 Switch 102 Current path 104 Terminal 106 Terminal 108 Outgoing line 110 Return line 112 Separation point 114 Switching element 116 Actuator 118 Contact surface 120 Gap 122 Close force 124 Lorentz force 126 Blow magnet

200 element 202 recess 204 actuator

300 extinguishing device 302 secondary path 304 fuse element 306 secondary electrode 308 prong 310 extinguishing comb

400 switching arc 402 partial arc

500 cutting wedge 502 ladder 504 abutment 506 taper 600 gap

Claims

EXPECTATIONS

1. Electrical switch (100) for separating a current path (102), the switch (100) having an outgoing line (108) with a separating point (112) for separating the current path (102), wherein a separating point (112) has a Switching element (114) which is movable at least on one side for opening and / or closing the separation point (112) is arranged in the outgoing line (108), the switching element (114) in a closed position on a movable side having a contact point (118) to the outgoing line (108) ), wherein the switch (100) further has a return line (110) connected at one end of the outgoing line (108) in an electrically conductive manner to the outgoing line (108), an arrangement of outgoing line (108) and return line (110) that is essentially antiparallel spaced apart ) is designed at least in the area of the separation point (112) to provide a current-carrying current path (102) due to a local Lorentz force in the feed line (108) and the switching element (114) and / or a tight force (122) in the Ko To compensate at least partially the force acting on the switching element (114) by a Lorentz force (124) acting on the switching element (114) from the return line (110).

2. Switch (100) according to claim 1, wherein a length (L) of the switching element (114) in the direction of extension of the switching element (114) and a distance (d) between the switching element (114) and the return line (110) in a direction perpendicular to the direction of extent of the switching element (114) are dimensioned such that the force acting on the switching element (114) at the contact point (118) due to the local Lorentz force and / or the narrow force (122) is caused by the current-carrying current path (102) in the return line (110) caused Lorentz force (124) at a current intensity (I) flowing through the current-carrying current path (102), for which the switch (100) is designed, can be compensated to at least 50%.

3. Switch (100) according to one of the preceding claims, wherein the switching element (114) at the contact point (118) on a side directed towards the return line (110) releasably rests against the outgoing line (108).

4. Switch (100) according to one of the preceding claims, in which the switching element (114) for opening the separation point (112) can be moved into an intermediate space (120) between the outgoing line (108) and the return line (110).

5. Switch (100) according to one of the preceding claims, further comprising an actuator (116) for bringing the switching element (114) towards and moving the switching element (114) away from the contact point (118).

6. Switch (100) according to one of the preceding claims, in which the switching element (114) is designed as a switching bridge movable on both sides, the switching bridge being aligned essentially parallel to the return line (110).

7. Switch (100) according to one of the preceding claims, with an extinguishing device (300) for extinguishing a switching arc (400) resulting when the current-carrying separation point (112) is disconnected, the extinguishing device (300) having a fuse element (304) that is currentless in normal operation a secondary path (302) to the current path (102), wherein the fuse element (304) is connected between a connection to a first side of the separation point (112) and a secondary electrode (306) of the secondary path (302), the secondary electrode (306 ) is arranged in the region of a second side of the separation point (112) and is electrically isolated from the current path (102) during normal operation.

8. Switch (100) according to claim 7, further comprising an extinguishing comb with at least two prongs arranged adjacent to the separation point (112), the prongs (308) being aligned essentially parallel to one another, electrically separated from one another and over an opening width of the separation point (112) are arranged distributed, the secondary electrode (306) being connected to at least one of the prongs (308).

9. Switch (100) according to claim 8, wherein the prongs (308) of the extinguishing comb (310) are designed as plates aligned essentially parallel to one another, with a front edge of the plates spaced apart from the current path (102) in the region of the separation point (112 ) is arranged and is aligned substantially parallel to the current path (102).

10. Switch (100) according to one of the preceding claims, further comprising at least one blow magnet (126) which is arranged adjacent to the separation point (112) and is designed to deflect the switching arc (400) from the separation point (112).

11. Switch (100) according to one of the preceding claims, further comprising a movable, electrically insulating element (200) which can be pushed into the opened separation point (112) and an actuator (204) for moving the element (200).