EP0849761A2 - Overcurrent and short circuit trip device for an electric circuit breaker - Google Patents

Abstract

The trigger has a thermal triggering device, pref. in the form of a thermobimetallic device (40), and an electromagnetic impact armature trigger with armature (33), coil (34), yoke and core. The yoke has an arm (35) parallel to the coil axis. The thermal trigger is attached to the arm and lies parallel to the coil axis and to the yoke arm so that it is heated by the current-carrying coil and yoke. The length of the arm corresp. to that of the thermobimetallic element; the former is pref. equal to in length or longer than the latter.

Description

The invention relates to an overcurrent and short-circuit release for an electrical Installation switch, especially for a circuit breaker or residual current circuit breaker, with a thermal release, preferably with a thermal bimetal and an electromagnetic impact anchor trigger for an impact anchor, one Coil, a yoke and a core.

Miniature circuit breakers for protection against thermal overload and short circuit basically built the same. They have a magnetic release for short-circuit protection and a thermal release, usually with a bimetallic strip, for the overload protection. The thermal bimetallic strip is also referred to as bimetal or bimetal.

In known versions of circuit breakers, the coil of the magnetic release and current flows through the bimetal of the thermal release and heated directly with it. In the event of an overload, the thermal release will release due to the current heat a switch mechanism, and in rated operation the current flows through the triggers and that Device heats up due to power loss. With small rated currents, for example less than 4 amps, the thermal release, i.e. the bimetallic strip, additionally with a current-carrying winding made of resistance wire provided, which generates the heating necessary for the deflection.

The thermal bimetal is normally designed as a strip bimetal; instead of one Thermobimetal could also use a shape memory alloy strip will.

In a known arrangement, a bimetallic snap disk is used which is located directly and centrally in the axial direction next to the magnetic release, see DE-PS 36 37 275. From DE-OS 42 24 046 is known a thermomechanical To couple element with the anchor, the anchor in the cooled state of the thermomechanical element is outside of the magnetic circuit while passing through the heated thermomechanical element is pushed into the magnetic circuit, but only to the extent that it does not trigger it alone. Only when the Coil pulls the armature, the switching mechanism is triggered. In other known ones Arrangements (see AT-315 90 B, US-PS 5 001 446) is made of a tether spring Shape memory alloy used, which is arranged in the coil tube of the trip coil is. The coil spring is heated by the coil and expands when it reaches one certain temperature. This moves the anchor, which then moves over you Tappet unlatches the rear derailleur.

In DE-OS 27 51 451 an arrangement is described in which the parallel to the coil electromagnetic trigger is connected to a bimetal, one end of which is stationary and a contact point is provided at the other end. The arrangement is dimensioned so that the coil of the magnetic release one has significantly higher resistance than thermobimetal. The flows normally Main current over the bimetal parallel to the coil. As soon as an overcurrent or Short-circuit current occurs, the contact point on the bimetal opens and the current flows in its entirety over the coil. In this way, on the one hand, there is a trigger amplification achieved with overcurrent and on the other hand a current limitation. As another The advantage is mentioned by simply adjusting the bimetal to change the thermal release in other areas.

It is also known to use a resistance wire with a positive temperature coefficient to be connected in parallel to the coil winding of the magnetic release. In case of occurrence a short-circuit current, the resistance of the wire changes suddenly, the Current commutates into the trip coil and increases the amount on the inductive winding acting current. By suitable dimensioning of the trigger coil and the resistance wire can be achieved within the nominal current range above the resistance wire flows a much larger proportion of current than via the Trigger coil. This makes it possible to use the same magnetic release with the same inductive winding can be used for several nominal currents.

There are a large number of variants in all of these arrangements of coil and bimetal necessary to cover the entire nominal current range usual for miniature circuit breakers from 0.2 amperes to 63 amps as well as the different tripping characteristics to cover. Depending on the nominal current and tripping characteristic, different Bimetal materials and a variety of different coil wires as well as cage springs for setting the magnetic response value. In addition, the space requirement in all of these arrangements is quite large.

The object of the invention is through the structural design, arrangement and Assignment of thermal release and magnetic release over the entire nominal current range and the different tripping characteristics with a significantly reduced Realize the number of components.

This object is achieved by the characterizing features of the Claim 1.

The yoke then has a leg which runs parallel to the coil axis; of the thermal release is attached to this bar and runs parallel to the axis the coil and the leg of the yoke of the electromagnetic release, so that the thermal release is heated by the current-carrying coil and the yoke.

The length of the leg of the yoke is approximately equal to the length of the bimetal.

Because the thermobimetal is attached directly to the yoke and parallel to the longitudinal axis the coil runs, the space requirement of the two components is reduced and in addition, both components can be practically combined into a single unit will. The thermal release can be outside or inside the yoke lie, the leg) of the yoke on which the thermobimetal is arranged is due to different configurations also to an improved and cheaper Heating of the bimetal helps. The thermal trigger or that Thermobimetal can be arranged outside or inside the coil.

The thermal release can be electrically connected in parallel with or in series with the coil be.

There is also the possibility that the thermal release is not from Current flows through and from the coil heat or the heat of the yoke is directly heated.

According to a further embodiment of the invention, the can be parallel to the coil axis extending legs of the yoke have two leg webs on their Ends connected with connectors; the bimetal can then be attached to one of the connectors together with one end of the wire of the coil be attached and also run parallel to the coil.

The shape of the connectors can be U-shaped, with the open side of the U-shape faces radially outward from the coil; Thereby the bimetal can do so be attached, as shown in claim 9. In this case, the two get lost Legs of the yoke parallel to each other and the thermobimetal is located in the area that is delimited on both sides by the levels of the leg webs.

A further embodiment can be found in claim 10; there are the Leg webs in one plane and the bimetal is at the junction of the free ends of the leg webs attached.

Further advantageous refinements and improvements of the invention are the see further subclaims.

Using the drawing, in which some embodiments of the invention are shown are, the invention and other advantageous refinements and improvements the invention are explained and described in more detail.

Fig. 1 bis 6

drei unterschiedliche Ausgestaltungen der Erfindung, in unterschiedlichen Ansichten,

Fig. 7 bis 9

je eine unterschiedliche Schaltungsanordnung von Spule und Thermobimetall, und

Fig. 10

eine schematische Einsicht in einen Leitungschutzschalter zur Darstellung der Anordnung der einzelnen Komponenten innerhalb des Schaltgerätes.

Show it:

1 to 6

three different configurations of the invention, in different views,

7 to 9

a different circuit arrangement of coil and bimetal, and

Fig. 10

a schematic view of a circuit breaker to show the arrangement of the individual components within the switching device.

Reference is now made to FIG. 10.

10 shows an inside view of a circuit breaker 10 of the housing 11, which accommodates the individual components of the circuit breaker. The circuit breaker 10 has a switch lock 12, one from the switch lock driven contact lever 13 which is rotatably supported about a pivot point 14 is and at the free end of a movable contact piece 15 is attached. This movable contact piece 15 cooperates with a fixed contact piece 16 and if an arc occurs during a switching operation between the contact pieces 15 and 16 the arc travels with a base along an arc guide rail 17 in an arc quenching plate packet 18 in which the arc quenched becomes. The other base point of the arc runs along the shape of the contact piece 16. The hot switching gases flow out through a channel 19.

Terminals 20, 21 are provided on opposite narrow sides, and below the key switch 12 are a thermal release 22 and an electromagnetic release 23. The thermal release 22 and the electromagnetic Triggers 23 respond to overcurrent or short-circuit current; of the thermal trigger, which is designed in the form of a thermal bimetal, acts on the Switch lock 12 on the movable contact lever 13; the electromagnetic trigger 23 acts via a magnetic armature 24 directly on the movable contact lever and via a mechanical gear arrangement, not shown, also on the Switch lock so that the contact lever 13 is opened permanently in the event of a short circuit. At the bottom of the housing 11 there is a recess 25 with a fixed one Nose 26 and a movable nose 27 so that the circuit breaker 10th can be snapped onto a top-hat rail (not shown).

A switch toggle 28 is provided for switching on again after a switch-off action. with which the switch can also be switched off manually.

The assignment of the individual components switch lock, thermal and magnetic Triggers, terminals, contact levers, arc quenching plate package and the like. are different depending on the arrangement of a circuit breaker; 10 shows schematically a commercial embodiment, that of the circuit breaker S2 from ABB Stotz-Kontakt GmbH, Heidelberg, is essentially the same.

The invention is concerned with the assignment of electromagnetic release 23 and thermal trigger 22 to each other. In Fig. 10 it is shown that the thermal Trigger 22 between the switch 12 and the electromagnetic trigger 23 lies, of course, there is the possibility of relating to the thermal release the drawing plane in front of or behind the electromagnetic trigger.

1 to 9 are different configurations of electromagnetic according to the invention Triggers shown with thermal triggers.

1 and 2 show different views of a first embodiment of a electromagnetic and thermal release.

The trigger, as the combination is to be called in the following, according to FIG. 1 and 2 has the reference number 30. It has a yoke plate 31 on which a coil former 32 is attached, the inside of a core (not shown) and one Impact anchor 33 and around which a coil 34 is wound. On the yoke plate 31 adjoins a yoke leg 35 running perpendicular to it, which is parallel to The central axis of the coil runs and two webs 36 aligned parallel to one another and 37 which are parallel to the central axis of the coil 34. At their ends the webs 36 and 37 are each by means of a U-shaped connecting piece 38 and 39 connected to each other so that there is a U-shape, which is radial with its open side points away from the coil 34. At the connector 38, see Fig. 2, that is fixed end 41 of a bimetal 40 welded and additionally one end 42 of the coil 34. It can be seen that the fastening point on the outside or coil side of the U-shaped connecting piece 38.

The thermal bimetal 40 runs parallel or from the U-shaped connecting piece 38 approximately parallel to the coil axis up to the connecting piece 39 and projects beyond it or its front edge 43 visible at the front in FIG. 1, the free, movable End of the bimetal 44 within the U-shape of the U-shaped connector 39 is located. On the outer surface of the web 36 near the U-shaped connector 39 and near the bendable end 44 of the bimetal 40 a conductor 45 is connected so that a current flow through the conductor 45, the webs 36 and 37 to the connector 38 and from there to the coil 34.

The bimetal, which is in the immediate vicinity of the coil 34 approximately parallel to it The longitudinal axis is not flowed through by the current, but by the coil 34 and also indirectly heated by the webs 36, 37.

The bimetallic metal 40 is thus on the yoke limb projecting above the coil 34 attached to the side of the connecting piece 38 pointing towards the coil 34; the Fastening point is therefore between the yoke leg 35 and the coil 34. Das Thermobimetal 40 runs from the free end of the yoke leg 35 to the yoke plate 31 and protrudes above it, the bendable end 44 being outside the connecting piece 39, based on the coil 34 and within the U-shape of the connector 39 is located.

In a second embodiment according to FIGS. 3 and 4, a coil 50 is provided, which is assigned a yoke 51, which has a U-shape with different lengths Legs 52 and 53 represents. The bobbin 54 with the core, not shown is arranged perpendicular to the web 51 and runs parallel to the legs 52 and 53 between these.

The longer leg 53, which is longer than the coil body 54, has two leg webs 55 and 56, which are connected at their free ends by means of a connecting web 57 are connected. The leg webs 55, 56 lie in one plane. From Fig. 4 it can be seen that the fixed end 58 of a bimetallic metal 59 on the connecting web 57 is welded to the side facing the coil 50; on The thermobimetal 59 is also at the same point an end 60 of the coil wire the coil 50 welded. The thermal bimetal 59 is located between the Leg webs 55 and 56 and at the fixed, clamped end between the leg webs 55, 56 and the coil 50. It projects beyond the web 51 with the free end 61 of the yoke. The other end 62 of the coil wire is here on an L-shaped tab 63 attached to the other components, such as a connector or the like. Can be specified. That through the coil 50 and through the leg webs 56 and 55 flowing current heats the bimetallic metal 59, so that here too an indirect one Heating takes place. The leg 52 is, as can be seen in Fig. 4, with a Provide pin 64 which runs parallel to the coil axis.

In a third embodiment according to FIGS. 5 and 6, the coil 70 is around a coil former 71 wrapped around the inner surface of the web 72 of a U-shaped yoke 73 is attached together with a core, not shown. The U-shaped Yoke has two legs of different lengths) 74 and 75, one on the leg 75, which is the shorter leg), a pin 76 corresponding to the pin 64 is integrally formed (see Fig. 6). On the outer surface of the longer leg 75 is a Thermobimetall 77 attached, such that the fixed end 78 of the Thermobimetal 77 on the outside of the leg 75 at the free end of this Leg 75 is welded. An end 79 of the coil is also in the same place 70 attached. The thermobimetal 77 lies on the outside of the leg 75 and dominates with its free, bendable end 80 the web 72 of the yoke 73. Das other end 81 of the coil wire is connected to a terminal lug 82. The Thermobimetal 77 is accordingly also indirectly heated by the coil 70 here.

1 to 6, the thermal bimetal is in each case indirectly from the coil heat is heated; the current does not flow through the bimetal.

According to FIGS. 7 to 9, other electrical interconnections can of course also be used be provided by coil and bimetal.

In the embodiment according to FIG. 7, the magnetic release has a yoke 90 on which a bobbin 91 is fixed, around which the bobbin 92 is wound. The yoke 90 has two legs 93 and 94 of different lengths and on the longer leg 93 is a terminal lug 95 attached to which a bimetal 96 is attached is. The free end of the bimetal 96, which is in the area of the web 97 of the yoke 90 is connected to a stranded conductor 98 at one end 99 of the coil. The other end 100 of the coil is connected to the web 97. On the connection flag 95 connects a connecting conductor 101, the other end of which is connected to a connecting terminal 102 is connected.

The current flows from line 101 once through thermal bimetal 96 to the stranded conductor 98 and on the other hand via the leg 93, the end 100, through the coil 92 and over the other coil wire end 99 to a branch point 103 which is followed by a continuing conductor 104.

7, the current flows both through the coil and through the bimetal, so that here both are electrically connected in parallel.

8 is between the terminal 102 and the end 99 of the coil 92, a conductor 105 is connected; the other end 100 of the coil 92 is with connected to yoke 90; The thermobimetal 96 is connected to the connecting lug 95. The current flows from terminal 102 via line 105, coil 92, the yoke 90 with the leg 93 to the tab 95 and through the bimetal 96, see above that in the embodiment of Fig. 8, the two elements coil, yoke and bimetal are connected in series with each other.

9 shows the indirect heating of the bimetal by the coil according to FIGS. 1 to 6. The current flows from the terminal 102 the connecting line 105 to the end 99 of the coil 92; the other end 100 is to the tab 95 guided and flows on from there via the yoke leg 93. This will make it Thermobimetal 96 does not have current flowing through it, but rather the heat of the coil 92 and also indirectly heated by the heat of the yoke leg 93.

Of course it is possible, with small currents smaller than 4 amperes, also one indirect heating of the bimetallic 96 by wrapping with a To produce heating wire. In this case the heating wire would be connected in parallel to the coil, to overcome the resistance of the entire switch.

There is of course also the possibility in the arrangements of FIGS. 1 to 6 Introduce bimetal into the inside of the coil, i.e. between the coil body and the coil wire, taking care to ensure that between the coil wire and the bobbin has enough space. The arrangement is purely schematic in the Fig. 11 shown. The coil 110 is oval in shape; it surrounds a coil former 111 with circular cross-section and the thermobimetal 112; the bobbin 111 is in known manner attached to the bottom of a yoke and the bimetallic 112 protrudes then axially out of the space that is covered by the coil body or the coil is.

With all solutions, the yoke is traversed by the current and thus becomes the bimetal from the coil and the yoke leg, in the area of which the bimetal is located, heated. Accordingly, the yoke leg must have a certain longitudinal section cover the bimetallic strip, the length being such that the bimetallic strip is sufficiently heated by the yoke. In the embodiments according to FIGS. 1 to 6 is the fixed end of the bimetal at the free end of the yoke leg fastened and protrudes from the yoke web running perpendicular to the coil axis.

Claims (12)

Overcurrent and short-circuit release for an installation switch, in particular a circuit breaker, with a thermal release, which is preferably designed as a bimetallic strip, and with an electromagnetic impact anchor trigger with impact anchor, coil, yoke and core, characterized in that the yoke has a leg that is parallel runs to the coil axis that the thermal release is attached to the leg and parallel to the axis of the coil and to the leg of the yoke of the electromagnetic release, so that it is heated by the current-carrying coil and the current-carrying yoke. Trigger according to claim 1, characterized in that the length of the Leg corresponds to the length of the bimetal, preferably the same size or is bigger. Trigger according to claim 1 or 2, characterized in that the thermal Trigger is located outside the coil. Trigger according to claim 1 or 2, characterized in that the thermal Trigger is arranged inside the coil (Fig. 11). Trigger according to one of the preceding claims, characterized in that that the thermal release is connected in parallel to the coil and possibly in parallel to the yoke is. Trigger according to one of claims 1 to 3, characterized in that the thermal release is connected in series with the coil. Trigger according to one of claims 1 to 4, characterized in that the thermal release is not flowed through by the current and heated by the coil heat is. Trigger according to one of the preceding claims, characterized in that that the parallel to the coil axis leg (35) of the yoke two parallel Legs (36, 37) having at their ends with U-shaped connecting pieces (38, 39) are connected, and that the thermobimetal together with a End of the wire of the coil is attached to one of the connecting pieces (38) and runs parallel to the coil axis. Trigger according to claim 8, characterized in that the connecting pieces (38, 39) are U-shaped so that the U-shape radially outwards from the coil (34) it is open that the fixed end of the bimetal (40) between the connector (38) and the coil (34) at the free end of the leg (35) is attached and that the free end of the bimetallic metal (40) within the U-shape of the connector (39) and related to the coil (34) outside the connector (39) runs. Trigger according to one of claims 1 to 7, characterized in that the yoke is U-shaped, one of the legs being the coil (50) with the coil body Exceeds in the axial direction that this leg two lie in one plane Has leg webs (55, 56) at their free end by means of a connecting web (57) are interconnected, and that the thermobimetal (59) with the one end of the winding wire of the coil (50) on the surface facing the coil the connecting web (57) is attached. Trigger according to claim 10, characterized in that the thermobimetal between the two leg webs (55, 56) on the one hand and with the fixed end between the leg webs (55, 56) and the coil (50) and with the free end on the other hand runs outside the leg webs (55, 56) and the web (51) of the U-shaped Joches towers. Trigger according to one of the preceding claims, characterized in that that the yoke is U-shaped, with a leg that the coil (70) with the Coil body (71) protrudes that at the free end of the leg (75) on its outer surface the bimetal together with one end of the winding wire Coil (70) is attached and that the bimetallic strip parallel to the leg (75), touching this on the outer surface, runs and the web of the U-shape of the yoke towered over.

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