EP1168402B9 - Magnetic subassembly for a mocular electrical device with a limited width - Google Patents

Abstract

The magnetic sub assembly has an inductive coil mounted in a magnetic housing and having a switching mechanism lock. There is a spiral coil (1) with a magnetic housing and two sections extending radially at the coil edge. There is a platform section (3) unlocking the locking mechanism and controlled by a spring return when there is no over current.

Description

The present invention relates to a magnetic sub-assembly for modular electrical equipment of the circuit breaker type, allowing line cut in the event of a sudden overcurrent, as well as equipment fitted therewith.

Line protection circuit breakers currently include generally, in a modular housing with plastic shells, a circuit extending between two terminals and comprising a bimetallic strip thermal trip to protect the line against overloads, a fixed contact and a movable contact and, between a terminal and a fixed contact, an electromagnetic trip device or magnetic trigger.

The latter essentially comprises a coil with a core mobile associated with a striker to ensure, in the event of an overcurrent, the separation by separation of the movable contact and the fixed contact by means a mechanical lock to which the movable contact is secured, and which may tip over under the action of the striker.

In most cases, the trigger more specifically includes an induction coil, mounted longitudinally in a cylinder head magnetic, and surrounding said movable core associated with the striker as well a fixed core, a return spring arranged between the cores coming further complete the assembly. This spring allows in particular to return the moving core to the rest position, striker in position inactive, i.e. away from the mechanical lock making opening of the contacts by tilting the movable contact.

The cylinder head consists of a sheet of magnetic material surrounding the coil to correctly channel the field lines produced when the coil is traversed by a current. On either side of said coil, in an axial direction, the cylinder head comprises conventionally flanks facing each other, one of which is provided with fixed core, and at the level of which are arranged elements general attached to the magnetic sub-assembly, i.e. one of the circuit breaker connection terminals and fixed contact.

In the conventional configurations thus described, the coil takes usually the shape of a volume solenoid therefore substantially cylindrical, with axial and transverse dimensions vary by size, even from one copy to another for the same size, a dimensional dispersion cannot be excluded in the manufacture of coils. For a given caliber, it is however necessary to maintain a copper section and a polar section data.

Solenoids in fact occupy almost the entire width of a simple modular device, i.e. they extend transversely practically from one shell to the other of the case.

In the constant search for an optimization of the integration of components in modular line protection devices, coils have always represented an element occupying a space significant relatively in internal volume, and considered difficult to reduce.

When the device housing occupies a reduced volume corresponding to what is commonly called a half-module having a width of 8.9 mm, the aforementioned usual configurations of solenoid magnetic trip units cannot be used, because the width of the half-module boxes is reduced by half.

According to a technical solution notably described in the document DE-A-457 673, instead of a solenoidal coil, use is made of a flat coil with a diameter much larger than its dimension axial, which can then be inserted into a housing obeying the aforementioned standard of the half-module.

One of the objectives of the present invention is to provide a particular configuration which can be adapted to said half-modules, and based on a flat-looking coil according to the teaching of the document previous.

The structure used has a magnetic circuit comprising a fixed portion and a movable portion,
whose relative arrangement makes it possible to significantly increase the useful force of the element causing tripping.

The magnetic sub-assembly is more precisely composed conventionally an induction coil mounted in a cylinder head magnetic with a device for triggering the lock in view to separate the movable contact from the fixed contact, and has a flat configuration with a spiral coil with at least one layer winding cooperating with a magnetic U-shaped yoke comprising a core developing along the axis of the coil and two branches extend radially towards the periphery of said coil, the free edge of at least one of the branches being separated from a pallet closing the magnetic circuit by an air gap, said pallet being movable relative to the branches, capable of actuating said lock to make it trip in the event of an overcurrent and controlled by means of reminder bringing it away from said lock in the absence of overcurrent.

The proposed configuration implies not only a particularity structural of the coil, but also a geometry of the circuit magnetic materialized by the cylinder head adapted to this structure. He is at note that it is the mobile portion of said circuit which is provided for cooperate directly with the lock, without intermediate piece, which considerably simplifies the structure on the one hand, and the assembly on the other go.

However, the primary objective of the invention lies in a possibility of optimization obtained by combining the two functions of magnetic trip due to overcurrent and trip thermal due to overload.

To this end, according to the invention, the movable pallet is a bimetallic strip distorting under the effect of heat caused by an overcurrent.

For certain sizes, the ends of the said pallet are directly electrically connected on the one hand to one of the terminals of electrical equipment and on the other hand to the spiral coil.

In this case, a material with properties suitable for both aspects of operation, because it is then used on the one hand as part of a magnetic circuit, and on the other hand as a deformable blade under the effect of an increase of temperature.

According to a variant, in particular adapted to other sizes, the pallet mobile is a bimetallic strip which deforms under the effect of the heat produced by the coil, said bimetallic strip then not being connected to the electrical circuit of the apparatus.

In this case it is possible to use a palette that is separate from the bimetallic strip, fixed to its straight portion and located so that it can cooperate with the fixed magnetic circuit, said pallet being able to improve the magnetic performance of the bimetallic strip if applicable.

According to a possible configuration, the core of the magnetic yoke may consist of sheets stacked to limit the currents of Eddy, the branches being flat. To simplify manufacturing, a variant with a solid core can, however, be implemented.

The branches are actually attached to the two ends of the nucleus, hence the U-shaped configuration which in reality only relates to the fixed portion of the magnetic circuit.

So that a mechanical cooperation, in the form of the exercise of a force, may exist between the pallet and the trigger lock, at minus a portion of the pallet is positioned near an arm release of the lock, which is actuated by said portion when the pallet approaches at least one of the branches of the magnetic yoke under the effect of increased flow in the circuit magnetic.

Said lock is therefore arranged, relative to the pallet, such so that there can be contact when the latter moves, that is to say in fact so that part of the arm crosses the trajectory movement of the pallet.

Preferably, and in particular to respect the planar configuration aforementioned, the pallet actually presents a shape of blade of width substantially equal to the distance between the two branches of the cylinder head. More preferably, at least a portion of the arm of release of the lock is arranged between said branches.

The action zone is then located at the free end of the pallet, which does not imply any modification / addition across the width.

According to an advantageous structure, the pallet is movable in rotation about an axis parallel to the axis of the spiral coil, said axis being located near the end of at least one of the branches, the outside of the U-shaped magnetic yoke.

In other words, the moving part of the magnetic circuit permeable is rotated, which turns out particularly suitable since, depending on the position of the axis of rotation and the geometry of the pallet, we can consider reducing the air gap medium while maintaining an equal useful stroke for said pallet or at least its active portion: taking into account the specificities traditional magnetic circuit, the useful force will be there significantly increased.

According to one possibility, the movable pallet is bent, the axis of rotation being arranged at the elbow separating two straight portions of said pallet, one of said portions being arranged so that it closes the magnetic circuit of the U-shaped yoke and presents a gap with at least one of the branches of said cylinder head.

In this case, the elbow is particularly useful to allow keep an appropriate length for the thermal bimetallic strip, length it would have been difficult to accommodate when deployed in a modular enclosure. Moreover, as will be seen in more detail below, the section which is not directly used in the magnetic circuit can be used for adjustment of the bimetallic strip.

Preferably, the return means associated with the movable pallet consist of a torsion spring, arranged in the elbow separating the two straight-looking portions of said palette, one of which ends is fixed to the latter and the other end is integral with the electrical equipment box.

These means aim to give a stable rest position to the pallet when it is not moved under the effect of an overload or a short circuit. It should be noted that when the pallet moves by deformation of the bimetallic strip, the air gap of the magnetic circuit decreases and it can have a synergistic effect at the end of the race, improving performance of the system of the invention.

The de facto coupling of magnetic and thermal functions, and the existence of a favorable rotary configuration in particular because that it plays on the size of the air gap, contribute significantly to the efficiency of the subset of the invention.

This also applies to electrical equipment of the type circuit breakers, but sized in half-modules, and which are equipped magnetic sub-assemblies as described above.

• la figure 1 est une vue en perspective d'un sous-ensemble magnétique selon l'invention disposé dans un appareillage électrique de protection de lignes demi-module ;
• les figures 2a à 2c sont des schémas fonctionnels montrant la position relative des portions fixe et mobile du circuit magnétique en cas de surcharge et en cas de court-circuit ;
• la figure 3 représente une vue perspective du circuit électrique auquel s'applique l'invention :
• la figure 4 est une vue en perspective des dispositions relatives du circuit électrique et du circuit magnétique ; et
• la figure 5 est une vue en perspective éclatée de la totalité de l'appareillage demi-module de l'invention.

The invention will now be described in more detail, in particular with reference to the figures arranged in the appendix, for which:

• Figure 1 is a perspective view of a magnetic sub-assembly according to the invention disposed in an electrical apparatus for protecting half-module lines;
• FIGS. 2a to 2c are functional diagrams showing the relative position of the fixed and mobile portions of the magnetic circuit in the event of overload and in the event of a short circuit;
• FIG. 3 represents a perspective view of the electrical circuit to which the invention applies:
• Figure 4 is a perspective view of the relative arrangements of the electrical circuit and the magnetic circuit; and
• Figure 5 is an exploded perspective view of the entire half-module apparatus of the invention.

Referring to Figure 1, the housing (B) of the electrical equipment is figured in transparency, devoid of its usual components to except for the magnetic sub-assembly. This includes a spiral coil (1), a portion of fixed magnetic circuit composed a core (2) and two parallel branches (3) of planar appearance, and a bent mobile pallet (4), in this case a bimetallic strip.

The width of the magnetic yoke, which can be raised by example at the level of the parallel branches (3) is such that this subset magnetic is insertable in protective devices half-modules.

The pallet (4) is movable in rotation around an axis located in the bent part (see below). In normal operation, the position relative pallet (4) / branches (3) of the fixed circuit is as shown in FIG. 2a: in this case, obviously very diagrammatically, the portion (4a) of the pallet (4) participating in the magnetic circuit is not moved, and a nominal air gap is present between one of the branches (3) and said portion (4a).

The second portion (4b) located on the other side of the elbow is well heard also motionless. A return spring (5) brings the movable pallet (4) in normal operating position outside any overload or overcurrent. An adjustment member (6) of the bimetallic strip (4) cooperates with said party (4b), in particular for the purpose of settling its sensitivity. This member (6) is preferably a simple screw which supports on the end surface of the portion (4b), acting as a stop adjustable.

The arrow (7) symbolizes the trigger arm secured to the lock (not shown in this figure). In Figure 2a, the portion (4a) mobile is at a distance from this arm (7), since the operation is normal.

However, in Figure 2b and 2c, a trigger occurs by contact between the portion (4a) of the pallet (4) and said arm (7). The case shown in Figure 2b is that of an overload: the bimetallic strip (4) heats up, and the pallet (4) moves by deformation of the portion (4a), which comes into contact with the member (7) and consequently causes the disjunction.

In Figure 2c, the increase in flux in the magnetic circuit under the effect of a short circuit causes the rotation of the paddle (4), and therefore portions (4a, 4b) around the axis (A). This had the same effect: the lock toggles and the electrical contact is open.

The only elements of the invention which appear in FIG. 3 are the coil (1) spiral and the pallet (4) which plays the role of bimetal. The electrical circuit of a circuit breaker, taken as an example of modular line protection device, develops between two terminals (8, 9) in which the external conductors of the line. These terminals (8, 9), and more generally the elements of said circuit which are not specific to the invention, are well known and do not the subject of a detailed description.

The terminal (9) is connected via a conductive braid (10) to the pallet / bimetal strip (4) at its portion (4b) which corresponds substantially at one end of the bimetallic strip (4). The other end is connected, also via a conductive braid (11), to one of the ends of the coil (1). The fixed contact (12), extended by a sheet arc conduction (14) is secured to the other end of the coil (1). The configuration described illustrates a case in which the heating of the bimetallic strip (4) is direct.

The movable contact (13), integral with a trigger lock (not shown), is electrically connected by means of a braid flexible (15) to a conductive sheet (16) connected on the one hand to the second terminal (8) and secondly to a second conduction sheet arch (17).

In case of overload, the bimetallic strip (4) deforms, but the coil (1), also traversed by a current greater than that which crosses it in normal operation, increases the flux in the magnetic circuit, and creates a synergistic effect with said deformation to ensure the disjunction of the contacts (12, 13).

In the event of a short circuit, the bimetallic strip (4) does not have time to heat the flux in the magnetic circuit (see figure 2c) rotates it around the axis (A) and produces the tilting of the movable contact (13).

The same elements as in FIG. 3 appear in FIG. 4, with the fixed part of the magnetic circuit, i.e. the core (2) and the arms (3) between which is wound the coil (1).

Plates (18, 19) with a flat appearance extend downwards and the sides the branches (3), although being distinct from the latter. They have in particular for the function of channeling the magnetic field for a additional function for guiding and blowing the electric arc created at opening of contacts, which is however not the subject of this invention. In addition, in the contact area, these sheets (18, 19) allow the opening speed of the contacts (12, 13) to be increased by providing a magnetic effect identical to that which applies to the arc electric created at the time of opening.

This magnetic effect applies to the mobile contact, which is in somehow "blown" in the same way as the arc, by repulsion magnetic. The sheets (18, 19) also go up to the axis of rotation, so that the contacts (12, 13), and in particular the contact mobile (13) are entirely in the magnetic field.

Referring to Figure 5, all of the circuit breaker components is represented, most of them being housed in one of the half-shells (20) forming the housing (B), the other half-shell (21) being here envisaged as a cover for closing said housing (13). The aforementioned sheets (18, 19) also appear at the level of said half-shells (20, 21).

Thus, in a very conventional manner, this circuit breaker comprises a lever (22) handling connected in particular via a link (23) to a rotary lock (24) of which the movable contact (13) is integral. This lock (24), which can be tilted using return means, has an arm (7) or a protuberance which, when touched by the pallet (4) during movement, tilts it.

The half-shell (20) induces a first branch (3), the core (1) of the magnetic circuit, which we can clearly see here consists of a stack of sheets, as well as the fixed contact (12). In the lower part, the deionization plates (27, 28) allow the arc to be extinguished electric which is created when the contacts (12, 13) are opened.

An insulating middle wall (25) is then placed on these elements, allowing in particular to isolate the coil from the magnetic core (1) and of the first branch (3).

A second insulation element (26) is arranged between the coil (1) and the second branch (3), of the fixed magnetic circuit. The second half-hull (21) is then closed, and the product is thus mounted.

The description of the invention given above is an example, and does not can be considered as limiting the said invention. This one on the contrary includes all variants of shape, configuration etc ... which are within the reach of ordinary skill in the art, without departing from the scope of the invention as defined in the claims.

Claims (11)

1. Magnetic sub-assembly for a modular electrical device of the circuit-breaker type comprising a fixed contact (12) and a mobile contact (13) which is integral with a triggering lock, the said sub-assembly being composed of an induction coil (1) which is fitted in a magnetic yoke provided with a device for triggering the lock in order to separate the mobile contact (13) from the fixed contact (12) in the event of excess current, the said coil (1) co-operating with a magnetic yoke in the shape of a "U" comprising a core (2) which extends according to the axis of the coil (1) and two branches (3) which extend radially towards the periphery of the said coil (1), the free edge of at least one of the branches (3) being separated from a plate (4) which closes the magnetic circuit by means of an air gap, the said plate (4) being mobile relative to the branches (3), able to activate the said lock, in order to trigger it in the event of excess current, and controlled by return means (7) which return it to a distance from the said lock in the absence of excess current, characterised in that it has a flat configuration with a spiral coil (1) with at least one winding layer.
2. Magnetic sub-assembly for a modular electrical device according to the preceding claim, characterised in that the said core (2) of the magnetic yoke consists of stacked plates, the branches (3) having a flat form.
3. Magnetic sub-assembly for a modular electrical device according to claim 1, characterised in that the core (2) of the magnetic yoke is solid.
4. Magnetic sub-assembly for a modular electrical device according to any one of the preceding claims, characterised in that the mobile plate (4) is a bimetal strip which is deformed under the effect of excess current, the ends of the said bimetal strip (4) being connected electrically firstly to one of the coils of the electrical device and secondly to the spiral coil (1).
5. Magnetic sub-assembly for a modular electrical device according to any one of claims 1 to 3, characterised in that the mobile plate (4) is a bimetal strip which is deformed under the effect of the heat produced by the coil (1), the said bimetal strip (4) not being connected to the electric circuit of the device.
6. Magnetic sub-assembly for a modular electrical device according to any one of the preceding claims, characterised in that a portion (4a) of the mobile plate (4) is positioned in the vicinity of a triggering arm (7) of the lock, which arm is activated by the said portion (4a) when the plate (4) approaches at least one of the branches (3) of the magnetic yoke, under the effect of the increase of the flow in the magnetic circuit.
7. Magnetic sub-assembly for a modular electrical device according to the preceding claim, characterised in that at least one portion of the triggering arm (7) of the lock is disposed between the two branches (3) of the magnetic yoke.
8. Magnetic sub-assembly for a modular electrical device according to any one of the preceding claims, characterised in that the plate (4) is mobile in rotation around an axis (A) which is parallel to the axis of the spiral coil (1), the said axis (A) being situated in the vicinity of the end of one of the branches (3) outside the magnetic yoke in the shape of a "U".
9. Magnetic sub-assembly for a modular electrical device according to the preceding claim, characterised in that the mobile plate (4) is bent, the axis of rotation (A) being disposed at the level of the bend separating two straight portions (4a, 4b) of the said plate (4) one of the said portions (4a) being disposed such that it closes the closed magnetic circuit of the yoke in the shape of a "U" and has an air gap in relation to at least one of the branches (3) of the said yoke, the other portion permitting adjustment of the bimetal strip (4).
10. Magnetic sub-assembly for a modular electrical device according to the preceding claim, characterised in that the return means which are associated with the mobile plate consist of a torsion spring (5) which is disposed in the bend which separates the two portions (4a, 4b) with a straight form of the said plate (4) one of the ends of which is secured to the latter and the other end is integral with the case (B) of the electrical device.
11. Half-module electrical device of the circuit-breaker type comprising a magnetic sub-assembly according to the preceding claims.

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