EP0444283B1 - Automatic cutout with an electromagnetic trip - Google Patents

Abstract

In the automatic cutout having an electromagnetic trip (3) designed as an impact armature system, an energising winding (3a) is surrounded by a frame-shaped magnet yoke (5) formed by a ferromagnetic sheet-metal strip. Said yoke has an integrally arranged, horn-shaped fixed contact point (5d), which merges into an arc guide rail (5f) and interacts with a moving contact lever (8), which is arranged on the side of the trip (3) and in front of the end of an arc splitter stack (4a). In order structurally to simplify the magnet yoke (5), and to construct it in a material-saving manner, it is folded from one piece to form a frame-shaped closed iron return path surrounding the energising winding (3a). To this end, the magnet yoke (5) has a U-limbed region (5a, 5b, 5c), which is located above and on both end surfaces of the energising winding (3a) and is constructed at one limb end, together with the contact horn (5e), with a fixed contact point (5d), which is arranged without a transition and projects in the form of an ear. Connected thereto is a bent-back arc guide rail (5f) which, with the end of the free limb (5a), forms a rectangular frame corner without mutual contact, so that the shape of the magnet yoke (5), which is folded in one piece is completed. <IMAGE>

Description

The invention relates to a line circuit breaker with an electromagnetic trigger element designed as an impact armature system, the excitation winding of which is enclosed by a frame-shaped magnetic yoke formed from a ferromagnetic sheet-metal strip, which in turn has a horn-like fixed contact point arranged in one piece and merging into an arc running track, and with an arcing chamber located below the trigger element with quenching plates arranged parallel to the impact anchor system and with a movable contact device oriented perpendicular to it, to the side of the triggering element and in front of the end face of the quenching plate package.

Such a switching device is known from DE 30 31 549 A1. Here, a frame-shaped closed magnetic yoke completely surrounds the excitation winding of the release element. The fixed contact piece running out into an arc guide plate is connected to the magnetic yoke in that these parts are punched and folded in one piece from a refined sheet steel strip. In order to maintain the closed frame of the magnetic yoke, the legs overlap on the side of the fixed contact piece and are additionally riveted. A disadvantage of this magnetic release is the considerable additional expenditure in terms of quantity of relatively expensive material as well as an additional mechanical work process.

Furthermore, from DE-OS 1 966 598 an electrical miniature auto switch is known, in which a return plate surrounding the release magnet also serves as a carrier for the fixed contact piece and with a Arc deflector is provided. The latter is located very far from the magnetic yoke and is also bent at an angle to the axial direction of the release. Such an arcing chamber is not suitable for switches with the high switching capacity customary today.

The invention has for its object to simplify the construction of the magnetic yoke of the tripping device in a line circuit breaker of the type mentioned and to save material and at the same time to give it in the adjacent quenching chamber and contact area of the switch an optimal design for the arc to run off the contact point quickly can and a commutation of the arc on the fixed contact side can be excluded.

This object is achieved by a circuit breaker with the characterizing features of claim 1. Further developments and advantageous refinements of the invention are specified in the subclaims.

The invention is advantageous in that an inexpensive arc quenching device can be produced with little material, which also ensures a high running speed of the switching arc in the prechamber area. The arc is driven safely and quickly, particularly in the critical area in front of the quenching plates by the fixed contact piece and the arc guide rail, both of which are predominantly made of ferromagnetic material. Due to the special arrangement, the magnetic flux of the short-circuit current surrounding the arc guide rails is increased in the area of the prechamber space, and the very effective blowing that arises here ensures rapid arc discharge from the contact point. Furthermore, the proposed measures significantly reduce the tendency to re-ignition of the switch.

Fig. 1

zeigt schematisch einen Leitungsschutzschalter mit im Bereich des Auslöseorgans und der Löschkammer geöffneter oberer Gehäuseschale, während in

Fig. 2

ein Schnitt durch die Löschkammer gemäß der Linie II-II der Fig. 1 wiedergegeben ist. In

Fig. 3

ist das Auslöseorgan mit einem Magnetjoch in abgewandelter Form dargestellt, wobei

Fig. 4

die zugehörige Seitenansicht zeigt.

Fig. 5 und Fig. 6

zeigen weitere alternativ mögliche Ausführungsformen des Magnetjochs im Rahmen des Erfindungsgedankens.

The invention is explained in more detail below with reference to the drawing.

Fig. 1

schematically shows a circuit breaker with the upper housing shell open in the area of the triggering element and the arcing chamber, while in

Fig. 2

a section through the arcing chamber is shown along the line II-II of FIG. 1. In

Fig. 3

the trigger element is shown with a magnetic yoke in a modified form, wherein

Fig. 4

the associated side view shows.

5 and 6

show further alternative possible embodiments of the magnetic yoke within the scope of the inventive concept.

The narrow circuit breaker shown has a housing (1) formed from two housing shells (1a, 1b) and held together by a plurality of rivet bolts (1c), which accommodates a switching mechanism (2) which is only indicated in the upper part. An electromagnetic release element (3) is arranged in the central area of the housing, while the base area located underneath is predominantly designed as an extinguishing chamber (4). This is largely filled with quenching plates (4a) arranged parallel to the bottom surface of the switch and connected to one another in a packet-like manner at a distance, and delimited on their narrow sides by arc guiding rails (5f) or (6) flanking the quenching plates on both sides. The upper arc runner (5f) is part of a magnetic yoke (5) which surrounds an excitation winding (3a) in a frame shape as an iron yoke. Iron cores of an impact anchor system are in turn within the field winding (3b) arranged, which in the event of a short-circuit current gives off the unlatching stroke of the electromagnetic release member on the plunger (3c).

The magnetic yoke (5) is made in one piece from a sheet metal strip and has a U-leg area with a free leg (5a), a connecting yoke (5b) and a contact-side leg (5c) above and on both end faces of the excitation winding (3a) whose leg end is seamlessly formed an ear-shaped protruding fixed contact point (5d) with a contact horn (5e) bent backwards, which ultimately merges into the upper arc running rail (5f). The magnetic yoke with its sections (5a, 5b, 5c, 5f) forms an almost iron-closed rectangular frame around the field winding (3a). As can easily be seen from the figures, the end of the contact-side leg (5c) in the transition to the fixed contact point (5d) and the contact horn (5c), which runs obliquely in front of the front contour of the upper quenching plates, are constricted almost flush with the corner in the transition to the arc guide rail (5f), while at the opposite corner of the frame the end of the free leg (5a) strives at right angles to the free end of the arc runner (5f), but without touching it. A partition wall (not shown) in the housing between the excitation winding and the arc runner (5f) ensures that, in the event of a short-circuit current under the influence of the magnetic forces, no conductive connection between the leg (5a) and the arc runner (5f) can occur. This is essential insofar as a reversal of the current direction occurs when touching this corner of the frame and thus magnetic blowing would be impeded.

Furthermore, the excitation coil (3a) is connected on the one hand to an output terminal (7) and on the other hand to the contact-side leg (5c), preferably by a welding process, so that it lies in series with the fixed contact point (5d), which is in particular due to a soldered-on contact plate (5d ′) is marked. A movable contact lever (8), which is only shown schematically, works on this and is connected in series with an input terminal (10) via a flexible line (8a), a thermal release (9) and a connecting line (10a). The thermal release (9) in the form of a bimetal is connected in a manner not shown to one end of the arc guide rail (6) and is adjustable there.

In the preferred embodiment, the two arc guide rails (5f, 6) are provided with a longitudinally running, transversely profiled bead (5f ', 6') (Fig. 1, Fig. 2) which protrude approximately in the direction of the quenching plates (4) the center of each arc runner, d. H. are impressed approximately in the pivoting plane of the movable contact lever (8). The bead on the upper arc rail (5f) begins directly below the contact plate (5d ') and preferably ends flush with it. This ensures that during a switch-off process, the switching arc running under the effect of the magnetic blowing field from the contact point (5d ', 8') runs along with its base points on the bead and is well guided in the stack of fire-extinguishing sheets, additional measures limiting the side of the Switch arc.

The same applies to the opposite base point of the switching arc, that of the opening contact lever (8) under the effect of the magnetic Blows field jumps to the lower ferromagnetic arc rail (6) and can run there along the bead (6 ') in the quenching plate package. The arc is driven safely and effectively in the critical area of the pre-chamber space and in front of the quenching plates (4a), because of the one-piece magnetic yoke in the contact area (5d, 5e), which consists mainly of ferromagnetic material, and in the transition to the upper arc runner (5f) of these parts surrounding magnetic flux is amplified. A rapid arc discharge from the contact horns along the two arc guide rails into the quenching plate package is thus ensured without backfiring at the contact point.

In a modified embodiment (Fig. 3, Fig. 4) the trigger member (3) in the area below the excitation winding (3a) is provided with a separating cut or longitudinal slot (5g) in the magnetic yoke, so that in addition to the opposite legs (5a, 5b , 5c) of the yoke, which is kept narrower and only in the switch center plane, there is a longitudinal web (5h) on one side, which is angled directly at the end of the contact-side leg (5c) in the direction of the free leg (5a), leaving out the contact point area and directly at the end. This creates a completely closed iron frame around the field winding. In addition to the longitudinal web (5h), the actual arc running rail (5f) is guided approximately parallel at a distance and, in addition to the smooth-surface design shown, can also be provided with a cross-profiled bead according to FIGS. 1 and 2.

A further modification of the subject matter of the invention, in particular at high currents, is the use of a composite material as the starting material for the Magnetic yoke (5). Here, the sheet metal strip made of an iron alloy is provided with a plating (5 ') made of a highly conductive material, preferably copper, which can have a maximum of half the strip thickness (Fig. 5). The plated outside of the sheet metal strip with a total thickness of about 1 mm is turned away from the excitation winding (3a) and is thus in a highly conductive connection with the contact point (5d) or (5d '). In order to also connect the excitation winding directly to the plated material in a way that is favorable for production, a connecting lug (5i) is preferably bent inwards on the contact-side leg of the magnetic yoke, on which one end of the winding has contact contact with the plated material side. This results in a low resistance between the field winding and the contact point, which is advantageous at higher nominal currents.

A similar advantageous effect results in the embodiment according to FIG. 6, in which a bridge part (5k) made of a highly conductive material is arranged between the field winding and the contact point. The bridge part follows the outer contour of the magnetic yoke in the ear-shaped projecting contact area (5d) and lies there tightly on the outside, one end being connected to the excitation winding (3a), while the other end can be designed directly as a contact point. This can be achieved, for example, by applying silver (5k ') on the copper base material of the bridge part, so that an additional contact plate is not required. The function of the separate iron-closed magnetic yoke in the sense described at the beginning is also fully retained in this version.

Claims (10)

1. Circuit breaker with an electromagnetic trip organ (3), which is constructed as solenoid system (3b) and the excitation winding (3a) of which is surrounded by a frame-shaped magnet yoke (5), which is formed of one ferromagnetic metal strip and in its turn displays a hornlike fixed contact point (5d), which is arranged in one piece and passes over into an arcing rail (5f), and with a quenching chamber (4), which is disposed underneath the trip organ, with metal quenching plates (4a), arranged parallelly to the solenoid system as well as with a movable contact equipment (8), which is arranged perpendicularly thereto and arranged laterally of the trip organ and in front of the end face of the metal quench plate packet, characterised thereby, that the magnet yoke (5), starting out from a U-limbed region (5a, 5b, 5c) situated above and towards both end faces of the excitation winding (3a), is formed at one limb end with the fixed contact point (5d), which projects in ear shape and is arranged without transition, together with a contact horn (5e) and is folded, by means of the bent-back arcing rail (5f) adjoining thereat,in one piece into a magnetic return circuit, which is closed in frame shape and surrounds the excitation winding (3a).
2. Switch according to claim 1, characterised thereby, that the free limb end (5a), which is remote from the fixed contact point (5d), of the magnet yoke (5) and the free end of the arcing rail (5f) are shaped to be abutting at right angles without mutual contact as frame corner.
3. Switch according to claim 1 and 2, characterised thereby, that the free end of the arcing rail (5f) is prolonged to be standing freely beyond the free limb (5a) of the magnet yoke (5) and at a spacing from its limb end.
4. Switch according to claim 1 to 3, characterised thereby, that the arcing rail (5f) and the contact horn (5e) are provided with a transversely profiled corrugation (5f′) in longitudinal direction.
5. Switch according to claim 4, characterised thereby, that the corrugation (5′) is arranged approximately in the pivot plane of the movable contact equipment (8) and stamped in to be projecting in the direction of the metal quenching plates (4a).
6. Switch according to claim 4 or 5, characterised thereby, that the corrugation (5′) is formed directly underneath a contact platelet (5d′) of the fixed contact point at the same height and beginning with its surface at the contact side.
7. Switch according to one of the claims 1 to 6, characterised thereby, that an about parallelly extending longitudinal web (5b) is formed in axial direction of the excitation winding (3a) by means of a separating slit (5g) at the arcing rail (5f) and bent from the limb (5c) at the contact side of the U-shaped magnet yoke (5) directly as closed iron frame around the excitation winding (3a) whilst omitting the fixed contact point (5d) and the arcing horn (5e).
8. Switch according to one of the claims 1 to 7, characterised thereby, that the magnet yoke (5) is made of a ferromagnetic sheet metal strip with a plating (5′) of a material of good conductivity at one side, wherein the ferromagnetic material side faces the excitation winding (3a).
9. Switch according to one of the claims 1 to 8, characterised thereby, that a connecting tag (5i) bent in the direction of the arcing rail (5f) is formed at the limb (5c) at the contact side of the magnet yoke (5) for the direct electrically conducting connection of the plating (5′) with the wire of the excitation winding (3a).
10. Switch according to one one of the claims 1 to 9, characterised thereby, that the fixed contact point (5d) and the end of the excitation winding (3a) facing it are conductively connected by means of a bridge part (5k) resting on the ferromagnetic material of the magnet yoke (5).

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