EP1805845B1 - Electric switching device comprising magnetic and/or fluidic adjusting elements - Google Patents

Abstract

The invention relates to an electric switching device (1), in particular a high-frequency switching device, comprising an elongate electrical switching element (4) comprising a contact end (6) which is arranged between two counter contact elements (7a, 7b) which are separated by a transversal distance and which can be displaced in a transversal manner in relation to the longitudinal direction thereof, against one or the other counter contact elements (7a, 7b), by two adjusting elements which are arranged on both sides adjacent to the switching element (4). In order to prevent or at least reduce the friction processes during switching, the switching element (4) is made at least partially of magnetic material, and the adjusting elements are formed by magnets (13a, 13b), and for a switching process, the efficiency of the magnet (13a, 13b) which is arranged in relation to the opposite side of the counter contact element (7a, 7b) which is to be contacted, can be limited or cancelled.

Description

The invention relates to an electrical switching device according to the preamble of claim 1 or 2.

In the DE 101 03 814 A1 a switching device is described, which serves to turn off a power line for a high-frequency attenuator via different damping elements. For this purpose, it has an elongated switching element, which is movable transversely to its longitudinal direction by an adjusting element and is thereby brought with a contact surface at one end selectively out of contact or in contact with a mating contact surface. In the contact position, the conduction of the electrical current at the contact surfaces is dependent inter alia on the contact surface and the mating contact surface. Impurities or particles can significantly affect the power line, especially if the impurities or particles are made of electrically non-conductive material.

Particularly important is a fault-free power line in attenuator lines, which is used as a reference in attenuation settings, e.g. of signal generators or network analyzers. Emissivity lines have e.g. several serially arranged four-pole switching devices with input and output side equal and constant characteristic impedance and each adjustable calibrated damping and thus also precise level.

In known electrical high-frequency switching devices, as z. B. are typically used in high-frequency attenuator lines, the lateral switching movement of a switching element by means of external mechanical force achieved by plunger, which push against the side of the switching element and move it. Due to the lateral pivoting movement, which performs the switching element and the linear thrusting movements of the plunger present on both sides of the switching element resulting in the contact region of the plunger and the switching element sliding, which lead to abrasion due to the resulting friction. In particular, when the switching device has a closed switching space, the risk of a contact failure by the abrasion generated by the friction is particularly large because the abrasion remains in the control room. But even with an open switch room there is a risk that the abrasion reaches between the contact surfaces and affects the electrical contact.

A switching device of the type specified is in the GB 1 021 047 A revealed, see Fig. 4 and the associated parts of description. In this prior art switching device, the contact end of an elongated electrical switching element is laterally moved by two arranged on both sides of the switching element magnet assemblies against an associated of two arranged on both sides mating contact elements.

From the US 4,468,532 A a switching device is described with an elongated and leaf-spring-shaped switching element, wherein the switching element is rigidly held with its end portion in a housing and the other end portion is movable by a fluid pressure in a switch space transversely against a mating contact element.

The invention is based on the object at an electrical switching device of the type specified friction operations and the resulting risk of deterioration of the electrical contact by abrasion to eliminate or at least reduce. In particular, the formation of abrasion in the vicinity of the contact surfaces should be avoided or at least avoided be reduced. In addition, a simple construction should be created.

This object is solved by the features of claim 1 or 2. Advantageous developments of the invention are described in the subclaims.

The invention is based on the finding that in a switching movement drive of the switching element with magnetic and / or fluid forces there is no need for mechanical movement contact between the switching element and the adjusting elements and therefore in this case generated with magnetic and / or fluid forces switching movements of the switching element in this respect neither a sliding friction takes place still a resulting abrasion is generated.

In the switching device according to the invention according to claim 1, the switching element is at least partially made of magnetic material, and the adjusting elements are formed by magnets, wherein for a switching operation, the effectiveness of the magnet, which is arranged with respect to the mating contact element to be contacted on the opposite side, can be reduced or canceled in that the effectiveness of the magnet can be reduced or canceled by a fluid flow of a nozzle which is arranged on the same side and directed towards the side of the switching element facing it and is optionally switchable on and off. Thus, during a switching operation, one of the two magnets thus fulfills the switching function, ie the movement of the switching element towards the respective mating contact, and the contact holding function on the mating contact element, wherein the effectiveness of the magnet opposite the mating contact element to be contacted is reduced or eliminated. This can be achieved for example by the fact that the opposite magnet is put out of action, for example, a solenoid is switched off or fed with less power, or the switching element with a magnetic force of the opposite Magnets, such as an electromagnet or a permanent magnet, exceeding adjusting force is moved to be contacted counter-contact element out.

The latter can be achieved according to the invention by means of a nozzle arranged on the opposite side, from which a fluid stream directed towards the facing side of the switching element flows out under pressure, which exerts on the switching element an adjusting force exceeding the magnetic force and moves the adjusting element towards the countercontact element to be contacted.

The term "fluid flow" within the meaning of the invention is preferably a gas stream, in particular an air stream, although a liquid stream is not excluded.

In the switching device according to the invention according to the independent claim 2 is arranged on the sides on which the mating contact elements, each having a nozzle for a pressurized fluid, wherein the nozzles are selectively switched on. In this embodiment of the invention, the switching movement of the switching is also causes elements and its contact with the respective mating contact element by a fluid ejected from the respective nozzle under pressure fluid flow generated by its impact on the switching element an adjusting force that moves the switching element to the other side and keeps in contact with the mating contact element.

In both switching devices according to the invention according to claim 1 and 2 is a non-contact switching. During the movement of the switching element as far as the mating contact element, there is thus neither a mechanical sliding friction nor a resulting abrasion, so that the electrical contact remains unimpaired in this respect.

The invention is characterized in each case by a simple configuration, which can be realized in a small construction, because it requires no mechanical connection between the switching element and the adjusting elements. Due to the lack of a mechanical connection, the embodiments according to the invention are variable and adaptable with respect to the distances between the switching element and the adjusting elements, so that they can be integrated into existing constructions in a simple and advantageous manner.

The invention can also be realized very advantageously by arranging a respective magnet and a nozzle on the sides on which the mating contact elements are arranged. In this combined embodiment, the nozzle in each case fulfills the movement function for the switching element, while the magnets in each case fulfill the contact holding function. Therefore, when the switching element is attracted by the respective magnet, the respective nozzle can be turned off. During movement, the respective magnet can support the movement function of the nozzle.

It contributes to a substantial simplification of the switching device, when the magnets are each formed by a permanent magnet. In such a case, the effectiveness of the respective magnet can be canceled by the nozzle disposed on the same side is turned on, the outflowing fluid flow exerts such a large motive force on the switching element that the magnetic holding force of the adjacent permanent magnet is overcome and thus suppressed.

To move the switching element against the mating contacts, it only requires a short-term exposure to the pressurized fluid, which is sufficient to move the switching element against the respective mating contact. Once the contact end is magnetically detected by the relevant permanent magnet, the fluid flow exiting the nozzle can be switched off again, resulting in a pressure fluid savings.

The embodiments of the invention are also very advantageous in combination with a leaf spring-shaped switching element whose broad sides facing the respective associated permanent magnet and / or the respectively associated nozzle. In this case, the switching element may have the dimensions of a thin film, so that the switching element with low movement forces in the direction of the respective opposite mating contact element is movable and durable in contact. In this case, the switching element does not need to be moved against the respectively associated permanent magnet. Even if a sufficient distance between the switching element and the permanent magnet is present in the contact position, the contact holding function is ensured at a sufficient magnetic force of the permanent magnet.

The embodiment of the invention is particularly suitable for a switching device in which the switching elements are arranged in a preferably sealed shelter of a housing. In this case, the case with a Form outlet through which the incoming pressure fluid can flow.

The pressure in the pressurized fluid can be e.g. by a pump with at least one reciprocable piston or a reciprocable diaphragm or by a compressor.

It further contributes to a simple and small construction, if with respect to a transverse plane two switching elements are arranged opposite one another with a longitudinal distance and with their mutually facing contact ends are each movable transversely against the associated permanent magnet. In this case, a common permanent magnet is preferably arranged on each side. As a result, a four-pole switching device can be realized in a simple manner.

Further developments of the invention lead to simple construction and mounting features that ensure a small, trouble-free, durable construction and safe operation and contact.

Fig. 1

eine erfindungsgemäße elektrische Schaltvorrichtung in einer Schaltstellung in prinzipieller Darstellung;

Fig. 2

die Schaltvorrichtung in einer anderen Funktionsstellung;

Fig. 3

die Schaltvorrichtung in einer anderen Schaltstellung;

Fig. 4

eine erfindungsgemäße Schaltvorrichtung in abgewandelter Ausgestaltung;

Fig. 5

eine erfindungsgemäße Schaltvorrichtung in weiter abgewandelter Ausgestaltung;

Fig. 6

eine erfindungsgemäße Schaltvorrichtung in weiter abgewandelter Ausgestaltung;

Fig. 7

eine vergrößerte Darstellung der in Fig. 6 mit X gekennzeichneten Einzelheit;

Fig. 8

eine erfindungsgemäße Schaltvorrichtung in weiter abgewandelter Ausgestaltung und

Fig. 9

eine erfindungsgemäße Schaltvorrichtung in weiter abgewandelter Ausgestaltung.

Below, advantageous embodiments of the invention will be explained in more detail with reference to several embodiments and drawings. Show it:

Fig. 1

an inventive electrical switching device in a switching position in a schematic representation;

Fig. 2

the switching device in another functional position;

Fig. 3

the switching device in another switching position;

Fig. 4

a switching device according to the invention in a modified embodiment;

Fig. 5

a switching device according to the invention in a further modified embodiment;

Fig. 6

a switching device according to the invention in a further modified embodiment;

Fig. 7

an enlarged view of in Fig. 6 detail marked with X;

Fig. 8

a switching device according to the invention in a further modified embodiment and

Fig. 9

a switching device according to the invention in a further modified embodiment.

The generally designated 1 switching device has an electrical line 2 with one or more switches 3, each with a transversely to the electrical line 2 back and forth movable switching element 4, which serves to open the line 2 or close. The switching element 4 is an elongated element which is permanently connected at its base end 5 to the line 2 and at its other end has a contact end 6, with it after a transverse movement in its contact position on one of two transversely spaced at a distance mating contact elements 7a, 7b is present. An open position can result in the hinted center position in which the contact end 6 has a lateral distance from the mating contact elements 7a, 7b.

In the embodiment, the switching device 1 is part of a so-called attenuation line with parallel switchable attenuator sections 2a, 2b, which can be selectively switched, wherein at least one attenuator section is attenuated and forms a damping line. It is a four-pole attenuation line formed by four switches 3 shown with two Eichleitungsabschnitten 2a, 2b and two preferably identically formed switching elements 4, which are arranged on both sides of a transversely to the electrical line 2 and approximately centrally between the mating contact elements 7a, 7b extending transverse plane 8 mirror images of each other, so that the contact ends 6 are directed towards each other, each disposed between two laterally spaced mating contact elements 7a, 7b and are selectively movable against one or the other mating contact element 7a, 7b. Since the on both sides of the transverse plane 8 arranged in mirror image switching devices are substantially equal, only the left of the transverse plane 8 arranged switching device will be described below.

The switching element 4 is preferably laterally elastically bendable, wherein its base end 5 is held on a holder 9 which is fixed on a base 11. As a flexible switching element, a spring tongue in the form of a flat strip is particularly well, in Fig. 1 is shown in plan view, so that its narrow side is visible and its two opposite broad sides facing the counter contact element 7a, 7b. The flat strip may also be formed by a thin film whose thickness is less than 1/10 mm and, for example, only a few microns.

According to a first embodiment of the invention is to perform a switching operation in which the switching element 4 is laterally moved to the one or the other mating contact element 7a, 7b, respectively on each side of a nozzle 12a, 12b for laterally moving the contact end 6 in the direction one or the other mating contact element 7a, 7b provided. For a switching operation, the respective nozzle 12a, 12b with a pressurized fluid, preferably compressed air, so strongly applied; that on the facing side of the switching element 4, in particular its broad side, impinging fluid flow, the switching element 4 with its contact end 6 respectively against the to be contacted counter contact element 7a, 7b is moved and rests against it. In a switching element made of elastically flexible material, such as a spring tongue in the form of a flat strip, the elastic restoring force is overcome during the movement of the switching element 4. This pressurization with the pressurized fluid is to be maintained as long as the relevant electrical contact is to be closed. After completion of the desired switching time, the respective nozzle 12a, 12b is switched off again, after which the switching element 4 may remain in its position or springs back in the embodiment due to its elastic bending stress automatically in its center position.

According to a second embodiment, a permanent magnet is arranged on each side of the switching element so that it can attract the switching element 4 by its magnetic force and hold on the respective mating contact element 7a, 7b, wherein the effectiveness of the permanent magnet, opposite to the contact element to be contacted 7a, 7b , reducible or cancelable. The permanent magnets thus have a magnetic force which is sufficient to attract the switching element 4 located in its range of motion and to hold it on the associated mating contact element 7a, 7b. Since the magnetic force of the respective opposing permanent magnet 13a, 13b is reduced or eliminated, the permanent magnet in operation is able to move the switching element 4 against the associated mating contact element 7a, 7b and to hold it.

According to the embodiment Fig. 1 and in the embodiments to be described, the switching device 1 has the nozzles 12a, 12b and the permanent magnets 13a, 13b, respectively. In this combined embodiment, the respective nozzle 12a, 12b needs to exert only a large amount of motive force on the switching element 4 with its fluid flow so that it is moved toward the associated mating contact element 7a, 7b. The associated permanent magnet then fulfills the contact holding function by he holds the switching element 4 on the mating contact element. However, the magnetic force of the permanent magnet can also support the movement of the switching element 4 to the associated contact element 7a, 7b out.

As soon as the relevant permanent magnet 13a, 13b can independently attract and / or hold the switching element 4 by its magnetic force, the associated nozzle 12a, 12b can be switched off.

The permanent magnet 13a, 13b is arranged in the embodiment with respect to the switching element 4 behind the associated mating contact element 7a or 7b, wherein the permanent magnet 13a, 13b through a disc or a block with a switching element 4 facing, e.g. level, front side is formed, on which the associated mating contact element 7a, 7b as a plate, strip or foil is applied and can be attached, e.g. by gluing or soldering.

The nozzle 12a, 12b is arranged and aligned laterally next to the switching element 4 so that its nozzle opening is directed towards the side of the switching element 4 facing it, which is preferably a broadside. In the exemplary embodiment, the nozzle 12a, 12b integrated into the mating contact element 7a, 7b and the permanent magnet 13a, 13b and formed by a through hole 12c in the permanent magnet 13a, 13b and in the mating contact element 7a, 7b. The nozzle 12a, 12b or the through hole 12c is connected at the rear to a supply line for a pressurized fluid, preferably compressed air.

The counter contact element 7a, 7b and the permanent magnet 13a, 13b are formed so large in the direction transverse to the drawing sheet dimension that on the one hand a sufficient contact point and on the other a sufficient magnetic field surface are available. In the embodiment, a common counter-contact element 7a, 7b and a common permanent magnet on each side 13a, 13b formed, which have in the longitudinal direction of the line 2 such a large dimension a that they overlap the two mutually facing contact ends 6 of the switching elements 4 sufficiently far to ensure on the one hand a sufficiently large contact point and on the other hand a sufficiently large magnetic field , Therefore, two nozzles 12a, 12b and through holes 12c are also disposed in the end portions of the common mating contact element 7a, 7b and permanent magnet 13a, 13b, respectively, so that their positions are directed to the end portion of the mating contact end 6.

On each side of the switching element 4 and the switching elements 4 is also a common pressure source 14 for acting on the nozzles 12a, 12b provided with a pressurized fluid, in particular compressed air. In the embodiment according to Fig. 1 is in each case the back of the permanent magnet 13a, 13b, a piston pump 15 in the form of a cylinder with a cylinder housing 15a and a piston 15b provided with a piston rod 15c. The permanent magnet 13a, 13b and the mating contact element 7a, 7b can thereby form the end wall of the cylinder housing facing the switching elements 4, the nozzles 12a, 12b or the through-holes 12c extending directly from the pressure chamber 15d of the cylinder. On the other side of the switching elements 4, the associated contact element 7b, the permanent magnet 13b and the pressure source 14 with respect to a vertical longitudinal plane 16 of the switching device 1 are arranged in mirror image and formed.

At the in Fig. 1 shown functional position, the switching elements 4 are in a the electrically conductive line connecting portion 2b electrically connecting position, the contact ends 6 abut the permanent magnet 13b and are held by the magnetic force in investment contract.

To switch the switching elements 4 in a position contacting the attenuator section 2a, the in Fig. 2 Piston 15b shown below moves upwardly by a piston drive, not shown, wherein the fluid located in the piston chamber flows out of the nozzles 12b as fluid flow and the switching elements 4 from the contact position with the lower permanent magnet 13b dissolves and up to the opposite mating contact element 7a or Permanent magnet 13a moves out. In this position, the switching elements 4 are held by the magnetic force of the upper permanent magnet 13a in contact with the mating contact element 7a, as it Fig. 3 shows. For example, at the same time, the upper piston 15b can be moved upward to allow movement of the switching elements 4 from the in Fig. 3 position shown in the in Fig. 1 position to be available. In this case, the fluid flow in each case the associated switching element 4 to move against the relevant permanent magnet 13a, the latter supports the movement by its magnetic force.

If the magnetic force of the permanent magnet 13a is correspondingly large enough, the thrust force of the fluid flow need only be so great that it moves the switching element 4 beyond the center position. Out of this position, the opposed permanent magnet 13a can pull the switching element toward itself and against the mating contact element 7a and hold it in contact for the required time. As soon as the effective magnetic force of the respective permanent magnet is so great that it is able to draw against the switching element 4 moved beyond the central position, the associated nozzle can be switched off since it and the fluid flow are no longer needed.

The switching element 4 may be a double switching element preferably extending in one piece beyond the holder or holders 9, which protrudes in both longitudinal directions from the holder 9, wherein the switching elements 4a facing away from each other with further movement drives 12 and counter contact elements indicated by dot-dash lines 7a, 7b of further Eichleitungsabschnitten cooperate. This is in Fig. 1 shown dashed right and left.

In the embodiment according to Fig. 4 in which the same or comparable parts are provided with the same reference numerals, instead of a piston pump, a diaphragm pump 17 is provided with a diaphragm 17a which generates a gas pressure or air pressure in the pressure chamber 15d and can be switched on and off according to the function described above.

It can also be a common pressure source 14, for example in the form of a piston pump 15 or diaphragm pump 17, may be provided for arranged on both sides of the longitudinal center plane 16 nozzle drives, for example as it Fig. 5 shows, in which a separate and common compressor 18 is provided, which is connected by supply lines 18a, 18b with the nozzles 12a, 12b. By in the supply lines 18a, 18b arranged and not shown valves, the compressed air can optionally be directed to the nozzles 12a, 12b.

In order to protect the interacting contact surfaces from contamination from the outside, it is advantageous to arrange the switching device 1 at least with respect to the contact surfaces having parts in the shelter 21 of a preferably sealed housing 22. In the embodiments in which above-described nozzles 12a, 12b are provided, an outlet opening, not shown, is provided in the wall of the shelter 21, which preferably opens automatically by a closure device (not shown) when the nozzles 12a, 12b generate an overpressure therein, and automatically closes when the pressure drops to a certain level.

The embodiment according to Fig. 6 in which the same or comparable parts are also given the same reference numerals are provided, such a housing 22 in a perspective view from above, wherein the shelter 21 through a lid 22a upper side can optionally be opened and closed.

In the construction according to Fig. 6 the base 11 is formed by a housing bottom 22b and two opposing side walls 22c, the lid 22a which can be placed thereon and two opposite end walls 22d, which are attached to the housing bottom 22b and the side walls 22c at the end face and screwed thereto. Preferably, the end walls 22d project beyond the side walls 22c, so that they can also receive the cover 22a between them and also be screwed thereto. In order to improve the sealing of the inside flat-fitting end walls 22d, they are each sealed by a sealing ring 23 made of elastically compressible material such as rubber or plastic, which preferably sits in an annular groove 24 in the contact surface of the end walls 22d and the contact surface slightly surmounted.

In the middle region of the end walls 22d, a passage 25 for the electrical line 2, each with a sleeve-shaped cable gland 26 is arranged which protrudes outwardly, and through which the electrical line 2 extends into the shelter 21 and sealed, for. screwed, is.

In the protective space 21 are preferably in the end regions, the holder 9 for the switching elements 4. The holder 9 may each be formed by a clamping device with jaws, between which the associated switching element 4 is clamped.

The 6 and 7 show a common supply line 12d respectively for arranged on both sides of the transverse plane 16 nozzles 12b. For example, from the respective common fluid connection two branch lines 12e to the channels or holes 12c in the magnets 13a, 13b and mating contact elements 7a, 7b extend. Such fluid connections can also according to the embodiment Fig. 5 be provided.

According to the embodiment 6 and 7 the attenuator sections 2a, 2b and counter contact elements 7a, 7b are arranged in the lower region of the magnets 13a, 13b. In the upper region, that is, via the switching elements 4, a bridge part 27 can be arranged and fixed between the permanent magnets 13a, 13b, the longitudinal dimension of which, for example, corresponds to the longitudinal dimension of the permanent magnets 13a, 13b.

On the side walls of the housing 22 in the region of the switching device 1, the indicated movement drives 12 are arranged in laterally projecting drive housings 28, which are e.g. laterally projecting tubes 28a, in particular round cross-section, which are arranged in matching recesses 29 in the lower housing part and in the lid 22a.

The motion drives 12 may be e.g. to act the above motion drives. In the context of the invention it is also possible, instead of permanent magnets 13a, 13b to arrange electromagnets whose magnetic force in the on state is so strong that it is sufficient to pull the associated switching element 4 towards him and to keep in abutting contact with the associated mating contact element , The magnetic force of the opposite electromagnet is reduced for the respective switching operation or the electromagnet is turned off, so that the respective active electromagnet can attract the switching element 4. In the presence of switching elements 4 in the form of the above-described spring tongues, the respective switching element 4 is attracted in each case from its central position to be contacted to the counter contact element 7a, 7b.

This variant with electromagnet is suitable for an arrangement and function without or with the nozzles 12th

An associated electronic control device 31 may be disposed on one of the two drive housings 28, e.g. at the end facing away from the housing 22.

The embodiment according to Fig. 8 , in which also the same or identical parts are provided with the same reference numerals, and in which the cover 22a is omitted for reasons of simplicity, differs from the above-described embodiments in that the nozzles 12 in the longitudinal direction of the switching elements 4 in addition to the mating contact elements 7a, 7b and Magnets 13a, 13b are arranged on the lower housing part. Also in this longitudinal region remote from the contact end 6, the switching elements 4 can be moved with a correspondingly strong fluid flow.

According to the embodiment Fig. 8 the nozzles 12a, 12b are formed by protruding from the inner sides 32 tubes, for example, can be inserted into holes in the inner sides 32. In these embodiments, supply line portions to the nozzles 12a, 12b extend through the side walls 22c, respectively.

In the embodiments according to the Fig. 6 to 8 are the permanent magnets 13a, 13b, for example, formed in an adapted Lötklotzform.

According to the embodiment Fig. 9 , in which also the same or comparable parts are provided with the same reference numerals, permanent magnets 13a, 13b are provided, which are formed for example in a fork shape. The respective opposing magnets are preferably facing each other with opposite poles N, S.

In the context of the invention, a plurality of switching devices 1 can be arranged one behind the other in the housing 22 or in its shelter 21 in the longitudinal direction of the line 2, as it is in Fig. 1 is hinted at.

Claims (14)

1. Electrical switching device (1), in particular highfrequency switching device, with an elongated electrical switching element (4) which is disposed with a contact end (6) between two mating contact elements (7a, 7b), which are at a transverse spacing from one another, and can be moved by two displacement elements, disposed on both sides next to the switching element (4), transversely to its longitudinal direction against either the one or the other mating contact element (7a, 7b),
   wherein the switching element (4) consists at least partly of magnetic material and the displacement elements are formed by magnets (13a, 13b),
   and wherein, for a switching operation, the effectiveness of the respective magnet (13a, 13b) which is disposed on the opposite side relative to the mating contact element (7a, 7b) which is to be contacted can be reduced or terminated,
   characterised in
   that the effectiveness of the magnet (13a, 13b) can be reduced or terminated by a fluid stream of a nozzle (12a, 12b) which is disposed on the same side and is directed at the side of the switching element (4) which faces it and can be optionally switched on and switched off.
2. Electrical switching device (1), in particular highfrequency switching device, with an elongated electrical switching element (4) which is disposed with a contact end (6) between two mating contact elements (7a, 7b), which are at a transverse spacing from one another, and can be moved by two displacement elements, disposed on both sides next to the switching element (4), transversely to its longitudinal direction against either the one or the other mating contact element (7a, 7b),
   wherein the switching element (4) consists at least partly of magnetic material, and a magnet (13a, 13b) for holding the contact element (4) in the contact position with the respective mating contact element (7a, 7b) through magnetic force is disposed on each side,
   characterised in
   that at least one nozzle (12a, 12b) for a pressure fluid is in each case disposed on the sides of the switching element (4) on which the mating contact elements (7a, 7b) are disposed, which nozzle is directed at the side of the switching element (4) which faces it.
3. Switching device according to Claim 1 or 2,
   characterised in
   that the magnets (13a, 13b) are permanent magnets or electromagnets, the magnetic force of which can be optionally reduced and switched off.
4. Switching device according to any one of the preceding Claims,
   characterised in
   that the switching element (4) is resiliently flexible in the transverse direction.
5. Switching device according to Claim 4,
   characterised in
   that the switching element (4) is formed by a spring tongue whose broad sides face the mating contact elements (7a, 7b).
6. Switching device according to any one of the preceding Claims,
   characterised in
   that the magnets (13a, 13b) are disposed behind the mating contact elements (7a, 7b), in particular lying against the rear sides thereof.
7. Switching device according to Claim 6,
   characterised in
   that the mating contact elements (7a, 7b) are in each case firmly connected to the associated magnets (13a, 13b), e.g. soldered thereto.
8. Switching device according to any one of the preceding Claims,
   characterised in
   that two switching elements (4) are disposed opposite one another relative to a transverse plane (8) and can be moved with their mutually facing contact ends (6) transversely against mating contact elements (7a, 7b) disposed on both sides, and a respective magnet (13a, 13b) and/or a nozzle (12a, 12b) are/is associated with the two switching elements (4) laterally opposite.
9. Switching device according to any one of the preceding Claims,
   characterised in
   that a respective pressure source (14) or a common pressure source (14) is associated with the nozzles (12a, 12b), this being connected to the nozzles (12a, 12b) through supply lines (12c, 12d, 12e; 18a, 18b).
10. Switching device according to Claim 9,
    characterised in
    that the pressure source or the pressure sources (14) is or are in each case formed by a piston pump or diaphragm pump or a compressor.
11. Switching device according to any one of the preceding Claims,
    characterized in
    that the nozzles (12a, 12b) are borne by the mating contact elements (7a, 7b) and/or by the magnets (13a, 13b), in particular being formed by holes (12c) disposed therein.
12. Switching device according to any one of the preceding Claims,
    characterised in
    that the nozzles (12a, 12b) are disposed next to the mating contact elements (7a, 7b) and/or the magnets (13a, 13b).
13. Switching device according to any one of the preceding Claims,
    characterized in
    that one or a plurality of switching devices (1) disposed in series in the longitudinal direction is or are disposed in a protective chamber (21) of a housing (22).
14. Switching device according to any one of the preceding Claims,
    characterised in
    that the fluid stream is a gas stream, in particular an air stream.

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