DE102009021773B4 - Thermal release and electrical switching device with a thermal release - Google Patents

Abstract

Thermal release (34) for an electrical installation switching device (1), in particular a circuit breaker, comprising a strip (2) of bimetallic strip or of a shape memory alloy, wherein the strip (2) with its attachment end (3) on an extension (31) of an arc guide rail (12) is fixed and the extension (31) forms a U-shape, wherein the extension (31) to the guide rail (12) adjoining the first leg (32), a U-shaped bending point (5) and one of the U -shaped bending point (5) subsequent second leg (4), characterized in that the first leg (32) of the extension (31) is clamped to the inside of the housing, and that the bending point (5) and the second leg (4 ) are slotted so that the second leg (4) is divided into a holding arm (41) and a contact arm (42), the strip (2) being fixed to the free end (6) of the support arm (41), and wherein the contact arm (42) horizontally bent to a terminal (9) and connected to a terminal rail (29) of the terminal (9).

Description

The invention relates to a thermal release for an electrical installation switching device, in particular a circuit breaker comprising a strip of bimetallic strip or of a shape memory alloy, wherein the strip is fastened with its attachment end to an extension of an arc guide rail and the extension forms a U-shape, wherein the extension has a first leg adjoining the guide rail, a U-shaped bending point and a second leg adjoining the U-shaped bending point, according to the preamble of claim 1.

The invention is further based on an electrical switching device, in particular a circuit breaker, with a running between a first and a second terminal current path, with a movable contact piece, with an arc guide rail and with a thermal release.

A generic circuit breaker is for example in the DE 10 2008 006 863 A1 shown. It has an access and an output terminal with a current path passed through it by the switching device. The current path leads via a contact point which is formed between a moveable contact lever mounted on a movable and a fixed contact piece, as well as at least one thermal, often additionally via an electromagnetic release, of which the thermal release in the event of an overcurrent and the electromagnetic release contribute to the elimination of the switching device when a short-circuit current occurs. In this case, the thermal release acts when triggered on a Verklinkungsstelle within a switching mechanism, which is coupled to the movable contact lever, to their unlatching. If the Verklinkungsstelle unlatched, the contact lever is pivoted so that the movable and the fixed contact piece are separated. The electromagnetic release opens when a short-circuit current occurs, the contact lever directly by impact; At the same time, the electromagnetic release also actuates the switch lock so that the switching device is permanently open.

The DE 695 14 050 T2 shows a thermal subunit adapted to be integrated into a circuit breaker having in a housing one or more current paths each extending between an input terminal and an output terminal and having a pair of fixed and movable contacts, an arc quenching chamber is assigned, wherein at least one of these current paths comprises one or more Ausrückorgane, which is associated with a safety mechanism that controls the entirety of these movable contacts, said current path of the combination of this thermal subunit, a clamp, a thermal bimetal disengagement comprising an arcing horn and a movable contact, with another subunit comprising at least one clamp, an arcing horn and a fixed contact, the corresponding arc extinguishing chamber being between the respective arcing image is located horns of these two subunits, said thermal subunit having an integral part which simultaneously forms the arcing horn, the electrical connection between the clamp and the bimetallic element and the support of the bimetallic element, the latter being welded to the one-piece part, wherein the one-piece part by cutting a two-material plate, the first of which is highly conductive and the second of which is adapted to the good formation of an electrical arc, and then obtained by such bending, that a first part of this part, entirely made of the first material , which forms an electrical connection between the clamp and the bimetallic element and a second part of this part, which has emerged entirely from the second material, forms an arcing horn.

The DE 44 45 170 A1 shows a thermal release for an electrical installation switching device, with a cantilevered bimetallic strip, wherein the clamping point is located at the end of an arc guide, which leads the emerging when opening the contact point switching arc in an arc extinguishing chamber. The current is supplied to the bimetallic strip via a first stranded wire welded to the bimetallic strip, and at least one further stranded wire is welded to the bimetallic strip to remove the current again. The installation of a generic thermal release in a service switching device is expensive.

The present invention is therefore in the light of the prior art, the object of further developing a generic thermal release so that its installation in a generic service switching device is simplified. Furthermore, the present invention has the object to provide a service switching device with a thermal release, simplifies its assembly and the arc guide is improved.

The problem underlying the invention is achieved with respect to the thermal release according to the invention by a generic thermal release with the With regard to the improved service switching device, the object is achieved by a generic service switching device having the features of claim 4.

According to the invention, the first leg of the extension is clamped to the inside of the housing, and the bending point and the second leg are slotted, so that the second leg is divided into a holding arm and a contact arm, wherein the strip is attached to the free end of the support arm, and wherein the contact arm is bent horizontally to a terminal and connected to a terminal rail of the terminal.

The advantage of the embodiment according to the invention is that a strand for contacting the bimetallic strip is omitted, because this is mechanically and electrically connected to the free end of the support arm, and the electrical contact with the terminal rail of the terminal via the contact arm of the extension. This opens up the possibility of easier mounting of the thermal release according to the invention.

According to a particularly advantageous embodiment of the invention, the holding arm carries a projecting flag, which serves as a pivoting surface for an adjusting. This is associated with the advantage of a space-saving arrangement of the thermal release in the housing of a service switching device. The adjustment means can act on the support arm without interfering with the bimetallic strip. The bimetallic strip is attached to the free end of the support arm, the adjustment acts on the tab on the support arm, but just past the bimetallic strip. According to a particularly advantageous embodiment of the invention, the thermal release with the guide rail, the terminal and the strip is designed as a prefabricated module and in a service switching device, in particular a circuit breaker used. Thus, the installation of an installation switching device with a thermal release according to the invention is very simplified.

An installation switching device according to the invention is characterized in that the thermal release comprises a strip of bimetallic strip or of a shape memory alloy, wherein the strip is fastened with its attachment end to an extension of an arc guide rail and the extension forms a U-shape, wherein the extension one to the guide rail subsequent first tavern, a U-shaped bend and a subsequent to the U-shaped bend second leg, wherein the first leg of the extension is clamped to the inside of the housing, and wherein the bending point and the second leg are slotted; such that the second leg is divided into a support arm and a contact arm, the strip being attached to the free end of the support arm, and wherein the contact arm is horizontally bent to a terminal and connected to a terminal rail of the terminal.

According to a particularly advantageous embodiment of the invention, the holding arm carries a projecting flag, which serves as a pivoting surface for an adjusting. In a particularly advantageous embodiment, the adjusting means is an adjusting screw, which is mounted in a housing-fixed thread. The installation of the service switching device is simplified.

According to a particularly advantageous embodiment of the invention is mounted with thermal release and open contact point, the movable contact piece next to the bending point. The bending point according to the invention is the U-bend of the U-shaped extension. The current flow of the current path through the inventive installation switching device extends from the access terminal via the terminal rail, the contact arm, the bending point, the support arm through the bimetallic strip. The U-shaped bend represents a current-carrying loop. In the inventive position of the bending point next to the movable contact piece of the U-bend of the bending point acts as a large Blasschleife. After opening the contact point commutes the base of the switching arc of the movable contact piece on the first leg of the extension. The current path then passes through the loop of the bending point and the arc. In this case, the electromagnetic blowing action is amplified by the inventive U-shaped bend on the arc, which contributes to a faster shrinkage of the arc in the arc extinguishing chamber and thus to a faster erasing the arc.

According to a particularly advantageous embodiment of the invention, the first leg of the extension is mounted fixed to the housing. This can for example be done by the first leg of the extension is clamped between housing-fixed ribs on the inside of the housing shells. The advantage is that with the housing-fixed mounting of the first leg and the attachment end of the bimetallic strip is fixed to the housing fixed. The bimetallic strip is clamped on one side at the attachment end. If the first leg of the extension and the clamping point according to the invention are fixed to the housing, a long-term stable adjustment of the thermal release is given. By the adjusting screw namely the opening of the U-shape of the extension is changed and thereby the distance between the Verklinkungsstelle and the free end of the bimetallic strip. Once set, this distance should not change under nominal conditions, therefore, the opening of the U-shape of the extension should not change. The housing-fixed storage of the first leg of the extension allows this.

According to a particularly advantageous embodiment of the invention, the thermal release with the guide rail, the terminal and the strip is designed as a prefabricated module and inserted into the service switching device. An installation switching device is so easy to install.

Further advantageous embodiments and improvements of the invention and further advantages can be taken from the subclaims.

figure description

Figures and description serve to better understand the subject. Articles or parts of objects which are substantially the same or similar may be given the same reference numerals. The figures are merely a schematic representation of an embodiment of the invention.

Showing:

1 a view of a thermal release according to the invention, and

2 a schematic view of a service switching device with a thermal release according to the invention.

In the figures, identical or equivalent components or elements are provided with the same reference numerals.

2 shows schematically an insight into an open housing of an electrical installation device 1 , here a circuit breaker. Between an access clamp 9 and an outgoing terminal 10 A current path initially runs over a terminal rail 29 , a first conductor piece welded thereto 14 to the end of the bearing in the form of a U-bend 5 a holding leg 4 , At the free end 6 of the holding thigh 4 is a strip 2 made of bimetal with its fastening end 3 welded. The opposite, free end 7 of the bimetallic strip 2 is with a wire 20 connected. This leads the current flow to one in a storage location 21 pivotally mounted contact lever 17 , which at its free end a movable contact piece 18 wearing. This forms together with a solid contact piece 19 a contact point. From the solid contact piece 19 the current path continues to run via a magnetic release 16 to the outgoing terminal 10 , In the 2 is the contact lever 17 shown in solid line in its off position, with dashed line in its closed position. In the off position, when the contact point is open, is the movable contact piece 18 next to the U-shaped bearing end 5 ,

If the current in the main current path remains above the rated current for a longer time, then one speaks of an overcurrent, bends the bimetallic strip 2 with its free, the fastening end opposite end due to the current heat caused in him by the overcurrent so far out that he has an action line 22 on a switch lock 8th acts there and ensures that a Verklinkungsstelle is unlatched. The realization of the interaction of the bimetallic strip with the switch lock 8th is feasible in different ways, one possibility is in the already mentioned DE 10 2008 006 863 A1 shown. After unlocking the Verklinkungsstelle the rear derailleur acts on a line of action 24 on the contact lever 17 and pivots it in a clockwise direction, so that the movable contact piece 18 from the fixed contact piece 19 disconnected and the contact point opened and through the switch lock 8th is kept open, see the solid drawn position of the contact lever 17 ,

A restart can be done via a gear knob 27 done by an action line 26 with the switch lock 8th cooperates and when actuated a Wiederverklinken the Verklinkungsstelle allowed when the bimetallic strip 2 has bent back to its original position after the overcurrent has subsided. The adjustment of the bimetallic strip 2 via an adjusting screw 13 , This is stored in a screw thread fixed to the housing, not shown here. The screw thread can for example be molded with its threaded sleeve on the inside of the housing shell. The adjusting screw pivots the holding leg 4 at the end of its storage 5 , Thus, it changes the opening of the U-shape between the holding leg 4 and the first leg 32 , As the bimetallic strip 2 at the bottom of the retaining leg 4 is welded, is by pivoting the retaining leg 4 the distance of the free operating end 7 of the bimetallic strip 2 from the switch lock 8th adjustable.

If a short-circuit current flows through the current path, ie a current that increases to a multiple of the rated current in a very short time, the magnetic release will respond 16 at. This then beats over a line of action 25 directly and quickly the contact lever 17 on, at the same time it acts over one line of action 23 also on the switch lock 8th for its unlatching and for the permanent keeping open of the contact point.

In a quick impact of the contact point is formed between the moving apart contact pieces a switching arc. This commutates after a short time on a Festkontaktleitschiene 30 and over a first leg 32 on an arc guide rail 12 and gets into an arc quenching chamber 15 led to extinction. As long as the arc has not yet extinguished, this carries the short-circuit current The short-circuit current flows in this time until the extinction of the arc on the first conductor piece 14 , the U-shaped end of the bearing 5 , the arc and the fixed contact rail. The U-shaped bearing end is a current-carrying loop. In the inventive position of the bearing end next to the movable contact piece 18 in the open position of the contact point, the U-bend of the bearing end acts like a large blown loop. In this case, the electromagnetic blowing action is amplified by the inventive U-shaped bend on the arc, which contributes to a faster shrinkage of the arc in the arc extinguishing chamber and thus to a faster erasing the arc.

The arc guide rail 12 carries on its left, the contact point facing side, the aforementioned extension 31 , This has approximately a U-shape, with a first leg 32 , which is directly connected to the arc guide rail 12 connected, and a second leg 4 holding the holding thigh 4 forms and therefore as a holding leg 4 referred to as. The holding thigh 4 created by bending the extension 31 at the already mentioned end of storage 5 , also called bending point. The arc guide rail 12 with the extension 31 can be made of one piece. Advantageously, this is a stamped and bent part made of steel. Steel is preferred because of its magnetic properties, strength and low cost. The guardrail 12 and the first leg 32 are mounted and held fixed to the housing, which can be made possible in various ways, for example by clamping between webs on the inside of the housing. The holding thigh 4 must remain movable, as explained above in connection with the adjustment of the bimetallic strip. The tight seat of the first thigh 32 is important in terms of the constancy of the thermal tripping properties, as a result of the location of the bimetallic strip 2 relative to the switch lock 8th also remains fixed after adjusting once.

1 shows in a detached detail view the extension 31 and its connection to the access terminal 9 , One recognizes the one-piece design of arc guide rail 12 , first thigh 32 and second thigh 4 as a stamped bent part made of steel. At the upper bend, the end of the warehouse 5 The steel strip is slotted. This results in two parallel partial strips 41 . 42 , One of these partial strips is as a holding arm 41 bent down. The adjacent partial strip 42 is also called a contact arm 42 is designated and after a short course vertically bent down again, horizontally in the direction of the access terminal 9 pointing out. He thus forms the first conductor piece 14 at a junction 33 with the busbar of the access terminal 9 , the terminal rail 29 , is welded. The access terminal 9 For example, it may be a known double-stroke cylinder clamp. The terminal rail 29 is a bus bar against which an inserted connection conductor is pressed with tightened or screwed terminal and thereby an electrical and mechanical connection between the connection conductor and the terminal rail is made. The assembly comprising the arc guide rail 12 , the extension 31 , the bimetallic strip 2 (not shown in 1 ) and the over the terminal rail 29 welded on access terminal 9 can be manufactured as a prefabricated unit and used during installation in the service switching device in a simple manner. There are in the assembly according to the invention no flexible strands used, but consistently solid busbars or conductor strips that are welded or soldered together, they could of course also be screwed or non-positively connected in any other known manner, positively and / or materially. The use of solid components and the elimination of flexible strands allows easy handling of the assembly during assembly.

The free end 6 of the support arm 41 is stepped in the form of an L designed so that the mounting surface 61 at the end of the attachment 3 the Thermobimetallstreifens is welded, a distance from the support arm 41 having. The bimetallic strip 2 can therefore be free of the support arm 41 bend around his chuck. Above the clamping point is on the support arm a laterally projecting flag 43 appropriate. This forms the abutment for the adjusting screw 13 , The adjusting screw 13 does not press directly on the support arm 41 but on the surface of the flag 43 , The adjusting screw 13 thus runs in a plane next to the bimetallic strip 2 without affecting it. In this way, a very space-saving arrangement of the assembly of the thermal release 34 in the housing of the service switching device 1 allows.

LIST OF REFERENCE NUMBERS

1

Electrical switching device

2

Strip of bimetallic strip

3

attachment end

4

Holding leg, second leg

5

End of storage, bending point

6

free end

7

actuating end

8th

switch lock

9

first connection terminal

10

second connection terminal

12

arc guide

13

adjusting

14

first conductor piece

15

Arc chute

16

magnetic trigger

17

contact lever

18

movable contact piece

19

solid contact piece

20

braid

21

depository

22

line of action

23

line of action

24

line of action

25

line of action

26

line of action

27

shift knob

29

clamping rail

30

fixed contact guide rail

31

extension

32

first leg

33

junction

34

thermal trigger

41

holding arm

42

contact

43

Banner, flag

61

mounting surface

Claims (9)

Thermal release ( 34 ) for an electrical service switching device ( 1 ), in particular a circuit breaker comprising a strip ( 2 Thermobimetal or a shape memory alloy, the strip ( 2 ) with its attachment end ( 3 ) on an extension ( 31 ) an arc guide rail ( 12 ) and the extension ( 31 ) forms a U-shape, wherein the extension ( 31 ) one to the guide rail ( 12 ) subsequent first leg ( 32 ), a U-shaped bend ( 5 ) and one to the U-shaped bend ( 5 ) subsequent second leg ( 4 ), characterized in that the first leg ( 32 ) of the extension ( 31 ) is clamped on the inside of the housing, and that the bending point ( 5 ) and the second leg ( 4 ) are slotted so that the second leg ( 4 ) in a holding arm ( 41 ) and a contact arm ( 42 ), the strip ( 2 ) at the free end ( 6 ) of the holding arm ( 41 ), and wherein the contact arm ( 42 ) horizontally to a connection terminal ( 9 ) and with a terminal rail ( 29 ) of the terminal ( 9 ) connected is. Thermal release ( 34 ) according to claim 1, characterized in that the holding arm ( 41 ) a projecting flag ( 43 ), which serves as the articulation surface for an adjustment means ( 13 ) serves. Thermal release ( 34 ) according to claim 1, characterized in that the thermal release ( 34 ) with the guide rail ( 12 ), the terminal ( 9 ) and the strip ( 2 ) designed as a prefabricated module and in an installation switching device ( 1 ), in particular a circuit breaker, can be used. Electrical switching device ( 1 ), in particular circuit breaker, with a between a first and a second terminal ( 9 . 10 ) running current path, with a movable contact piece ( 18 ), with an arc guide rail ( 12 ) and with a thermal release ( 34 ) according to claim 1. Electrical switching device ( 1 ) according to claim 4, characterized in that the holding arm ( 41 ) a projecting flag ( 43 ), which serves as the articulation surface for an adjustment means ( 13 ) serves. Electrical switching device ( 1 ) according to claim 5, characterized in that the adjusting means is an adjusting screw which is mounted in a housing-fixed thread. Electrical switching device ( 1 ) according to claim 4, characterized in that when mounted thermal release ( 34 ) and opened contact point, the movable contact piece ( 5 ) next to the bending point ( 5 ) lies. Electrical switching device ( 1 ) according to claim 4, characterized in that the first leg ( 32 ) of the extension ( 31 ) is clamped between housing-fixed ribs on the inside of the housing shells. Electrical switching device ( 1 ) according to claim 4, characterized in that the thermal release ( 34 ) with the guide rail ( 12 ), the terminal ( 9 ) and the strip ( 2 ) as a prefabricated module and into the service switching device ( 1 ) is used.

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