EP0849761B1 - 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, according to the preamble of claims 1 and 3.

Miniature circuit breakers for protection against thermal overload and short circuit basically built the same. You have a magnetic trigger for the Short-circuit protection and a thermal release, usually with one Thermobimetal strips, for overload protection. The bimetallic strip is in hereinafter also referred to as bimetal or thermobimetal.

In known versions of circuit breakers, the coil of the Magnetic release and the bimetal of the thermal release flows through and heated directly with it. In the event of an overload, the thermal release trips due to the heat generated by the current 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 amperes, 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 become.

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 the magnetic circuit while it is 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 that The coil mechanism 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, 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 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 that within the nominal current range the resistance wire flows a much larger proportion of current than via the Trip coil. This makes it possible to use the same magnetic release with the same to use inductive winding 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 amps to 63 amps as well as the different tripping characteristics cover. Depending on the nominal current and tripping characteristics, different Bimetal materials and a variety of different coil wires as well as cage springs to adjust the magnetic response value. In addition, the space requirement in all of these arrangements is quite large.

A trigger of the type mentioned at the beginning has become known from FR 1 544 977, in which a coil with an armature and a thermal bimetal is provided. The yoke is u-shaped and runs with one leg inside the coil; on this thigh the bimetal is attached, which also reaches through the coil. The Thermobimetal is u-shaped, one of the legs with the leg of the yoke and the other leg is connected to a wire end of the winding so that obviously the thermal bimetal is traversed by the current, which is also understandable if you look at the length of the bimetal in relation to the axial extension of the Considered coil.

A trigger has become known from EP 0 037 490 A1 in which the thermal Trigger in the form of a strip of shape memory material arranged parallel to the coil is (see Fig. 3). The thermal release is not traversed by the current here. A similar embodiment can also be seen in FIGS. 11, 13 and 15, wherein nothing can be found about the arrangement of a yoke.

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 trigger characteristics with a significantly reduced Realize the number of components.

This object is achieved by the characterizing features of the Claim 1 or Claim 3.

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 become. The thermal release can be outside or inside the yoke lie. Due to the design of the yoke with the two leg webs and The arrangement of the thermal bimetal in the area in between will result in improved heating of the bimetallic metal produced, in which both leg webs for heating of the bimetal.

Further advantageous refinements and improvements of the invention are the others See 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 4

zwei unterschiedliche Ausgestaltungen der Erfindung, in unterschiedlichen Ansichten,

Fig. 5 bis 7

einige Ausführungsformen von Schaltungsanordnungen von Spule und Thermobimetall, und

Fig. 8

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

Show it:

1 to 4

two different configurations of the invention, in different views,

5 to 7

some embodiments of coil and thermobimetal circuitry, and

Fig. 8

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. 8.

Fig. 8 shows a view of a circuit breaker 10 and that inside 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 mounted about a pivot point 14 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 is 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; the thermal trigger, which is designed in the form of a thermobimetal, 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 10 on a top-hat rail (not shown) can be snapped on.

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; 8 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. 8 it is shown that the thermal Trigger 22 between the switch 12 and the electromagnetic trigger 23 is, of course, there is the possibility of relating to the thermal release to be placed in front of or behind the electromagnetic release on the plane of the drawing.

1 to 4 are different configurations of electromagnetic according to the invention 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 parallel webs 36 and 37, which run parallel to the central axis of the coil 34. Are at their ends the webs 36 and 37 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, whereby 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 connecting piece 38 and from there to the coil 34.

The bimetallic strip, which is in close proximity to 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 Thigh bars 55 and 56 and at the fixed, clamped end between the thigh bars 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 set. The 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.

1 to 4, the thermal bimetal is in each case indirectly from the coil heat is heated; the current does not flow through the bimetal.

5 to 8 show different electrical interconnections of Coil and bimetal shown.

5, the magnetic release has a yoke 90 on which a bobbin 91 is fixed, around which the coil 92 is wound. The yoke 90 has two legs 93 and 94 of different lengths and on the longer one Leg 93 is attached to a terminal lug 95, on which a bimetal 96th is appropriate. The free end of the bimetal 96, which is in the range of Web 97 of the yoke 90 is with a stranded conductor 98 with an end 99 of the Coil connected. The other end 100 of the coil is connected to the web 97. On the connecting lug 95 connects a connecting conductor 101, the other end of which a terminal 102 is connected.

The current flows from line 101 through thermal bimetal 96 to that 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.

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

6 is between a terminal 105 is connected to the terminal 102 and the end 99 of the coil 92; the other end 100 of the coil 92 is connected to the yoke 90; at the Terminal lug 95, the bimetal 96 is connected. The current flows from the Terminal 102 via line 105, coil 92, yoke 90 with leg 93 for Tab 95 and through the bimetal 96, so that in the embodiment according to FIG. 6 the two elements coil, yoke and thermobimetal are connected in series are.

The yoke shapes can also be used with these circuit arrangements Legs according to FIGS. 1 to 4 are used.

7 shows the indirect heating of the bimetal by 1 to 4. The current flows from the connection 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 from there via the yoke leg 93. This will make it Thermobimetal 96 does not flow through the current, but from 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 less than 4 amperes, also one indirect heating of the bimetallic 96 by wrapping with a To generate heating wire. In this case the heating wire would be connected in parallel to the coil, to overcome the resistance of the entire switch.

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 thermobimetal 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 4 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 (8)

1. Overcurrent and short-circuit release for a service switch, in particular for a circuit breaker, having a thermal release in the form of a bimetallic strip and having an electromagnetic impact armature release with impact armature, coil, yoke and core, with the yoke having a limb which runs parallel to the coil axis, on which the thermal release is mounted and runs parallel to the axis of the coil and to the limb of the yoke of the electromagnetic release so that it is heated by the coil through which the current flows and by the yoke through which the current flows, characterized in that that limb (35) of the yoke which runs parallel to the coil axis has two parallel limb webs (36, 37) which are connected at their ends to U-shaped connecting pieces (38, 39), in that the bimetallic strip is attached, together with one end of the wire of the coil, to one of the connecting pieces (38) and runs parallel to the coil axis and in the area between the limb webs.
2. Release according to Claim 1, characterized in that the connecting pieces (38, 39) are U-shaped, in that the U-shape is open to the outside radially away from the coil (34), in that the fixed end of the bimetallic strip (40) is attached to the free end of the limb (35) between the connecting piece (38) and the coil (34), and in that the free end of the bimetallic strip (40) runs within the U-shape of the connecting piece (39) and, with respect to the coil (34), outside the connecting piece (39).
3. Overcurrent and short-circuit release for a service switch, in particular for a circuit breaker, having a thermal release in the form of a bimetallic strip and having an electromagnetic impact armature release with impact armature, coil, yoke and core, with the yoke having a limb which runs parallel to the coil axis, on which the thermal release is mounted and runs parallel to the axis of the coil and to the limb of the yoke of the electromagnetic release so that it is heated by the coil through which the current flows and by the yoke through which the current flows, characterized in that the yoke is U-shaped and its web covers the coil at right angles to the coil axis, with one of the limbs overhanging the coil (50) with the coil former in the axial direction, in that this limb has two limb webs (55, 56) which lie in a plane and are connected to one another at their free end by means of a connecting web (57), and in that the bimetallic strip (59) is attached together with one end of the winding wire of the coil (50) to that surface of the connecting web (57) which faces the coil.
4. Release according to Claim 3, characterized in that the bimetallic strip runs between the two limb webs (55, 56) on the one hand and with the fixed end between the limb webs (55, 56) and the coil (50) and with the free end outside the limb webs (55, 56) on the other hand, and overhangs the web (51) of the U-shaped yoke.
5. Release according to one of the preceding claims, characterized in that the length of the limb corresponds to the length of the bimetallic strip, and is preferably of equal size or is larger.
6. Release according to one of Claims 1 to 5, characterized in that the thermal release is connected in parallel with the coil and possibly in parallel with the yoke.
7. Release according to one of Claims 1 to 5, characterized in that the thermal release is connected in series with the coil.
8. Release according to one of Claims 1 to 4, characterized in that the current does not flow through the thermal release, which is heated by the heat from the coil.

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