Patent Description:
A switching device can be a circuit breaker or a contactor. A circuit breaker is an electrical switch that is used to protect an electrical circuit from damage caused by the occurrence of a short circuit or by a large current that is lower than the current in the case of the short circuit but large enough to damage the electrical circuit. A contactor is an electrical switch that is used to switch a current on and off. Together with the protecting device, for example a fuse or a circuit breaker, the contactor has to cut the current in short circuit and overload cases.

The switching device comprises a moveable contact and a stationary contact. The moveable contact may be moved in a closed and open state. In the closed state, the movable contact is in electrical contact with the stationary contact of the switching device so that the switching device allows a current flow from an input terminal to an output terminal of the switching device. In an open state of the switching device, the moveable contact is separated from the stationary contact so that the flow of current between the input and output terminals of the switching device is interrupted.

When a separation of the moveable and stationary contact takes place, an arc is generated and produces breaking gases. These gases go through an extinguishing chamber of the switching device. The breaking gases usually flow out through an orifice of the switching device. The ionized hot gases transport fine particles from the housing and the contacts of the switching device out of the housing. The outflowing composite of the ionized breaking gases and the fine particles can ignite outside the housing, and the particle dust can burn explosively. The explosive combustion creates pressure that can damage tightly casing housings, bulkheads and adjacent equipment of the switching device. The combustion may affect the switching device itself and the surrounding components. Outflowing particles and combustion residues, for example, can be deposited as a layer on surrounding components, reducing isolation properties.

<CIT>, <CIT> and <CIT> relate to electric circuit breakers, where a cloth filter member is arranged near an outlet of the circuit breakers to capture debris and to perform cooling of breaking gases generated when separation of the contacts take place.

<CIT> relates to an electric circuit breaker comprising an arc chute that contains a plurality of spaced plates supported by side and back supports, wherein layers of the side supports comprise a plurality of woven cloth or glass fibers.

There is a desire to provide a switching device with effective cooling and filtering of outflowing gases so that an ignition and explosive combustion of the breaking gases outside of the switching device can be prevented as far as possible.

An embodiment of a switching device with effective cooling of outflowing gases is specified in claim <NUM>.

According to an embodiment of the switching device, the switching device comprises an arc extinguishing chamber and an orifice for the outflow of the breaking gases from the arc extinguishing chamber. The switching device further comprises a multilayer wire cloth or (knitted) fabric comprising at least a first wire layer and at least a second wire layer. The at least first and the second wire layer have a respective cloth or fabric structure. The at least first wire layer and the at least second wire layer are disposed in a stacked configuration in the orifice in a way that the cloth or fabric structure of the at least second wire layer is oriented in another direction than the cloth or fabric structure of the at least first wire layer.

According to an advantageous embodiment, one of the at least first and second wire layer of the multilayer wire cloth or fabric is layered with one weaving direction rotated by <NUM>° in comparison to the weaving direction of the adjacent one of the first and second wire layer. This ensures that a defined equal distance can be maintained between the layers of the multilayer wire cloth or fabric. If the wrap wire and the weft wire are nearly equal in diameter and distance, a rotation being greater than <NUM>° and less than <NUM>° must be selected to keep a constant thickness.

By stacking the various wire layers of the multilayer wire cloth or fabric with the at least second wire layer being arranged rotated in relation to the at least first wire layer, it can be further ensured that a direction of flow of the breaking gases flowing out through the orifice of the switching device changes from the at least first wire layer to the at least second rotated wire layer. The change of direction of the outflowing gases leads to a greater cooling effect of the outflowing breaking gases with small dimensions of the gas deionization device being embodied as the multilayer wire cloth or fabric.

The multilayer wire cloth or fabric is disposed in the orifice with a defined orientation. According to an advantageous embodiment the fabric layer of the at least first wire layer facing the extinguishing chamber has a coarse cloth/fabric structure, while the at least second wire layer facing the outside of the switching device has a fine cloth/fabric structure. Due to the fact that the fabric layers become increasingly finer towards the outside, the multilayer wire cloth or fabric provides a filter effect occurring towards the outside.

To ensure that the multilayer wire cloth or fabric can be installed in the orifice in the correct orientation, the multilayer wire cloth or fabric has a contour being different from the contour of an adjacent side of the cloth or fabric, for example a set bevel/chamfered edge, at at least one of the corners of the multilayer wire cloth or fabric. The surrounding housing is formed in the area of the orifice in such a way that an inversely shaped contour of the inner wall of the orifice fits the set bevel of the multilayer wire cloth or fabric. This ensures that the multilayer wire cloth or fabric cannot be installed in the wrong way in the orifice of the switching device.

According to the claimed embodiment of the switching device, the surrounding housing parts of the switching device forming the orifice comprise protruding ribs which are configured to support the multilayer wire cloth or fabric. This configuration ensures that the multilayer wire cloth or fabric can be loosely disposed in the orifice so that a supporting frame to hold the multilayer wire cloth or fabric in the orifice is not necessary. The loosely disposed multilayer wire cloth or fabric advantageously contributes to a cost-effective production of the switching device.

In order to further facilitate production of the multilayer wire cloth or fabric, the individual fabric layers may be connected to each other by pressing the fabric layers of the multilayer wire cloth at certain locations over a small area and welding them together at these points. The pressing and welding can be carried out in one manufacturing operation.

Additional features and advantages are set forth in the detailed description that follows and in part will be readily apparent to those skilled in the art from the description or recognized by practising the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are merely exemplary, and are intended to provide an overview or framework for understanding the nature and character of the claims.

The accompanying drawings are included to provide further understanding, and are incorporated in and constitute a part of the specification. The drawings illustrate one or more embodiments, and together with the detailed description serve to explain principles and operation of the various embodiments. As such, the disclosure will be more fully understood from the following detailed description, taken in conjunction with the accompanying figures in which:.

<FIG> shows an embodiment of a switching device <NUM> with effective cooling of outflowing breaking gases. The switching device <NUM> comprises a stationary/fixed contact <NUM> having a contact plate <NUM> and a moveable contact <NUM> having a contact plate <NUM>. In the open configuration of the switching device, the moveable contact <NUM> is electrically isolated from the stationary contact <NUM>. In the closed configuration, the moveable contact <NUM> is in electrical contact with the stationary contact <NUM> so that contact plates <NUM> and <NUM> are in contact with each other.

The switching device comprise terminals for fixing electrical wires to connect the switching device to an electrical circuit. <FIG> shows a screw <NUM> fixed by a nut <NUM> to a terminal side of port <NUM>. In a closed state of the switching device, a current flows through the switching device from one of the terminals via the connection of the stationary and the moveable contact to the other one of the terminals. In the case of a short circuit in the electrical circuit to which the switching device is connected, the high current flowing through the switching device is interrupted by separating the moveable contact <NUM> from the stationary contact <NUM>. In this case an electric arc is generated between the contact plates <NUM> and <NUM> and the amount of gas is so large that explosive combustion may occur.

In order to provide a propagation path for the arc, the switching device <NUM> comprises arc runners <NUM> leading an arc to an extinguishing chamber <NUM>. The arc extinguishing chamber <NUM> comprises a stack of cooling plates <NUM> which divide and cool the arc. By splitting the arc into smaller arcs within the arc extinguishing chamber <NUM>, the arc is cooled down while the arc voltage is increased and serves as an additional impedance which limits the circuit through the switching device.

When separation of the moveable and stationary contacts <NUM> and <NUM> takes place, breaking ionized gases are generated in the arc extinguishing chamber <NUM>. The switching device <NUM> comprises an orifice <NUM> for the outflow of the breaking gases from the arc extinguishing chamber <NUM>. The switching device <NUM> further comprises a multilayer wire cloth or fabric <NUM> being disposed in the orifice <NUM>. The multilayer wire cloth or fabric <NUM> is designed to perform cooling of the breaking gases so that an ignition and an explosive combustion of the gases outside of the switching device can be effectively prevented.

<FIG> shows a cross-sectional view of the switching device <NUM> from the bottom side. A bottom plate <NUM> covers the arc extinguishing chamber and the multilayer wire cloth or fabric <NUM>. <FIG> shows a perspective view of the switching device <NUM> with the multilayer wire cloth or fabric <NUM> being disposed in the orifice <NUM>. The orifice <NUM> is configured as an opening in an outer part <NUM>, for example a covering element, of the housing of the switching device.

<FIG> illustrates a cross-sectional view of the multilayer wire cloth or fabric <NUM> in an enlarged view. The multilayer wire cloth or fabric <NUM> comprises at least a first wire layer <NUM> and at least a second wire layer <NUM>. The at least first and the second wire layers have a respective cloth/fabric structure. The at least first wire layer <NUM> and the at least second wire layer <NUM> are disposed in a stacked configuration as shown in <FIG> and <FIG>, in the orifice <NUM>. In the stacked configuration of the multilayer wire cloth or fabric, the first wire layer may be disposed directly adjacent the second wire layer. As further illustrated in <FIG> and <FIG>, the stacked configuration of the multilayer wire cloth or fabric <NUM> is embodied such that the cloth/fabric structure of the at least second wire layer <NUM> is oriented in another direction than the cloth/fabric structure of the at least first wire layer <NUM>.

According to the claimed embodiment of the multilayer wire cloth or fabric <NUM>, each of the cloth/fabric structure of the at least first wire layer <NUM> and the at least second wire layer <NUM> comprises a plurality of wrap yarns <NUM>, <NUM> and weft yarns <NUM>, <NUM>. The respective weft yarns <NUM>, <NUM> of the at least first and second wire layer <NUM>, <NUM> are configuration as parallel straight wire yarns in the respective cloth/fabric structure of the at least first and second wire layer <NUM>, <NUM>. The respective wrap yarns <NUM>, <NUM> of the at least first and second wire layer <NUM>, <NUM> are configured as undulated wire yarns in the respective cloth/fabric structure of the at least first and second wire layer <NUM>, <NUM>. The respective wrap yarns <NUM>, <NUM> pass alternating over and under the successive weft yarns <NUM>, <NUM>.

According to the claimed embodiment, at least one of the wire layers of the multilayer wire cloth or fabric <NUM> is arranged in the stacked configuration of the wire layers with its weaving direction of wrap yarns and weft yarns rotated by an angle in relation to the other wire layers. The at least one rotated wire layer may, for example, be rotated in the stacked configuration of the plurality of wire layers, for example, by <NUM>° in relation to the at least one other wire layer, for example in relation the at least one adjacent wire layer.

The arrangement of at least one of the wire layers in another direction in comparison to the remainder of the wire layers ensures that a direction of flow of the breaking gases out of the extinguishing chamber <NUM> through the orifice <NUM> changes within the multilayer wire cloth or fabric <NUM>. The deflection of the gas flow within the multilayer wire cloth or fabric <NUM> enables an effective cooling of the breaking gases when flowing through the multilayer wire cloth or fabric.

<FIG> illustrate another embodiment of a multilayer wire cloth or fabric <NUM> not covered by the claims, wherein adjacent wire layers <NUM> and <NUM> (<FIG>) or adjacent wire layers <NUM> and <NUM> (<FIG>) are arranged in the same orientation. In the embodiment shown in <FIG>, the wire layers <NUM> and <NUM> are arranged above each other such that respective hills of wrap yarns <NUM>, <NUM> of the adjacent wire layers <NUM> and <NUM>, and respective valleys of the wrap yarns <NUM>, <NUM> of the adjacent wire layers <NUM> and <NUM> are placed above each other which leads to the same thickness, a higher pore size and a lower pressure drop of the multilayer wire cloth or fabric <NUM>. Referring to <FIG>, the wire layers <NUM> and <NUM> are placed above each other such that respective valleys and hills of wrap yarns <NUM>, <NUM> of adjacent wire layers are offset to each other in comparison to the wire layers <NUM> and <NUM> of <FIG> so that the multilayer wire cloth or fabric <NUM> has a smaller thickness, a lower pore size and a higher pressure drop in comparison to the multilayer wire cloth or fabric <NUM>. In conclusion, as illustrated in <FIG>, the thickness of the multilayer wire cloth or fabric <NUM> and <NUM> depends on the arrangement of the wire layers.

The arrangement of the at least first wire layer <NUM> and the at least second wire layer <NUM> of <FIG> ensures that the multilayer wire cloth or fabric <NUM> can be manufactured with a defined thickness, a defined pore size and a defined pressure drop. Moreover, the stacked configuration of the multilayer wire cloth or fabric <NUM> with different orientation of one of the wire layers in comparison to another one of the wire layers, in particular a directly adjacent wire layer, ensures that the multilayer wire cloth or fabric <NUM> can be provided with a defined equal distance between the wire layers.

According to an embodiment of the switching device <NUM>, in an orthogonal projection to the stacked configuration of the multilayer wire cloth or fabric <NUM>, the wrap yarns <NUM> in the at least first wire layer <NUM> are offset in relation to the wrap yarns <NUM> in the at least second wire layer <NUM> by a defined angle, for example up to <NUM>°. This means that, in the orthogonal projection to the stacked configuration of the multilayer wire cloth or fabric <NUM>, the wrap yarns <NUM> of the at least first wire layer <NUM> are perpendicular to the wrap yarns <NUM> of the at least second wire layer <NUM>. Furthermore, in the orthogonal projection to the stacked configuration of the multilayer wire cloth or fabric <NUM>, the weft yarns <NUM> in the at least first wire layer <NUM> are offset in relation to the weft yarns <NUM> in the at least second wire layer <NUM> by a defined angle, for example up to <NUM>°. In this case, the weft yarns <NUM> of the at least first wire layer <NUM> are arranged perpendicular to the weft yarns <NUM> of the at least second wire layer <NUM>.

<FIG> shows a perspective view of the multilayer wire cloth or fabric <NUM> comprising the at least first wire layer <NUM> and the at least second wire layer <NUM> in a stacked configuration. The cloth/fabric structure of the at least second wire layer <NUM> is arranged rotated in relation to the cloth/fabric structure of the at least first wire layer <NUM>.

Each of the at least first and second wire layers <NUM>, <NUM> comprises a plurality of mesh openings <NUM>, <NUM>. The mesh openings are located at the wide and narrow sides of the cloth or fabric <NUM>. The mesh openings <NUM> of the at least second wire layer <NUM> are smaller than the mesh openings <NUM> of the at least first wire layer <NUM>. According to an advantageous embodiment, the multilayer wire cloth or fabric <NUM> is disposed in the orifice <NUM> such that the at least first wire layer <NUM> is arranged closer to the arc extinguishing chamber <NUM> than the at least second wire layer <NUM>. This ensures that a filter effect occurs in the multilayer wire cloth or fabric <NUM> towards the outside of the switching device.

In order to manufacture the multilayer wire cloth or fabric <NUM>, the at least first wire layer <NUM> and the at least second wire layer <NUM> are pressed together at a plurality of areas <NUM>, <NUM>, <NUM> and <NUM> before welding. The at least first wire layer <NUM> and the at least second wire layer <NUM> are connected to each other by a respective welding connection <NUM> provided at the plurality of areas <NUM>, <NUM>, <NUM> and <NUM>. The plurality of areas <NUM>, <NUM>, <NUM> and <NUM> of the multilayer wire cloth or fabric <NUM> are spaced apart from each other, as shown in <FIG>. The pressed and welded areas <NUM>, <NUM>, <NUM> and <NUM> of the multilayer wire cloth or fabric <NUM> may be located near the corners of the multilayer wire cloth or fabric <NUM>. The manufacturing method allows to press the various wire layers in a small area which at the same time serve as points to perform the welding between the wire layers. The pressing and welding may be advantageously performed in one operation step.

Claim 1:
A switching device with effective cooling of outflowing gases, comprising:
- an arc extinguishing chamber (<NUM>),
- an orifice (<NUM>) for the outflow of the gases from the arc extinguishing chamber (<NUM>),
- a multilayer wire cloth or fabric (<NUM>) comprising at least a first wire layer (<NUM>) and at least a second wire layer (<NUM>), the at least first wire layer (<NUM>) and the at least second wire layer (<NUM>) having a respective cloth or fabric structure comprising respective wrap yarns (<NUM>, <NUM>) and weft yarns (<NUM>, <NUM>), characterised in that
- the at least first wire layer (<NUM>) and the at least second wire layer (<NUM>) are disposed in a stacked configuration in the orifice (<NUM>) in a way that a weaving direction of the wrap yarns (<NUM>) of the at least first wire layer (<NUM>) is rotated by an angle in relation to the weaving direction of the wrap yarns (<NUM>) of the at least second wire layer (<NUM>) and the weaving direction of the weft yarns (<NUM>) of the at least first wire layer (<NUM>) is rotated by an angle in relation to the weaving direction of the weft yarns (<NUM>) of the at least second wire layer (<NUM>) so that the cloth or fabric structure of the at least second wire layer (<NUM>) is oriented in another direction than the cloth or fabric structure of the at least first wire layer (<NUM>),
- and in that the multilayer wire cloth or fabric (<NUM>) is loosely disposed in the orifice (<NUM>) between ribs (<NUM>, <NUM>) of inner and outer parts of a housing (<NUM>, <NUM>) of the switching device.