Title of Invention

MAGNETIC SUBSYSTEM FOR MODULAR ELECTRIC EQUIPMENT AND ELECTRIC CIRCUIT BREAKER

Abstract

Magnetic subsystem for modular electric equipment and electric circuit breaker type, consisting of: - An induction coil (2), - A movable magnetic core (3) - A striker (6) moving along with the movable core (3), - An elastic return device activated by the movement of the striker (6). The movable core (3) is housed in a movable support (13), driven by the movable core (3) and integral with the striker (6).

Full Text

The present invention relates to a magnetic subsystem for modular electric equipment and electric circuit breaker. Circuit-breakers for line protection generally consist of a modular box in plastic mould, a circuit between two terminals and comprising a bimetallic thermostatic release to protect the line from overloads and, an electromagnetic unit between the binding post and a fixed contact, for cutting-off the magnetic release mechanism, often grouped along with these two components to form a magnetic subsystem. The magnetic release mechanism consists mainly of a coil with a moving core, linked with a striker for breaking the circuit, in case of excess current, by opening a moving contact operating along with a fixed contact. In most cases the release mechanism consists, specifically, of an induction coil mounted length-wise in a magnetic frame and wound around a moving core, to which a striker is linked, a tension spring placed between the cores to complete the assembly. This spring serves mainly to return the moving core to its open position, placing striker in the idle position, that is to say, at the distance of a mechanical lock enabling to open the contacts by changing the moving contact. The frame consists of a sheet of magnetic material, which is generally wound around the coil for correctly channeling the electric field patterns produced, when a current is passed through the coil. During assembly of the circuit breaker, the magnetic subsystems mounted in a single unit are then placed in a portion of the plastic mould of the box. It can be inferred from the function of these magnetic subsystems, that they are the essential components of the circuit breakers, and hence utmost care should be taken regarding their design, including numerous tests to prove the validity of proposed solutions. The main function being linked to the extremely high excess currents, some of these are naturally carried out under different configurations of short-circuit, or at the least, with current strengths many times their nominal value, based on which the performance of the magnetic subsystems are measured. During these periods of functioning under extreme conditions, one of the specifically and rigorously controlled parameters is the pulling force of the contacts. The purpose of these controls and the resulting adjustments is to improve the release conditions of the mechanical lock by an improved control of an electromagnetic release mechanism and the conveyed force of the striker. Heating of the various parts of the magnetic subsystem is also a sensitive parameter, for which tests under nominal or slightly higher intensity are carried out with a view to reduce it as much as possible. Thus it is known how to make magnetic subsystems on modular electronic equipment of the circuit-breaker type, which consists of: - an induction coil a moving magnetic core - a striker moving with the moving core an elastic return device required for the movement of the striker. Magnetic subsystems having a fixed guide roller, in which the moving core linked to the striker, as well as a fixed magnetic core, are known. While taking into account the functional parameters, particularly those pertaining to safety and which ensure reliability of pulling away in case of excess current, it becomes difficult to change any of the parameters without affecting the other functional parameters. One objective of the present invention is to reduce the number of components constituting this magnetic subsystem and to simplify them to facilitate assembly, while still preserving the reliability of this magnetic subsystem. Another objective of this invention is to improve the performance of this magnetic subsystem without increasing its size, so as to facilitate its integration on modular electric equipment. As per the invention, the moving core is housed in a moving support driven by a moving core, integral with the striker. Thus we have a moving mechanical subsystem with a simplified configuration whose assembly into the frame is also simplified. According to one embodiment, the moving support and the striker are made in one piece, say in plastic material. For example the moving support is a cylindrical part, one of whose ends in a rod constituting the striker. Thus the number of magnetic subsystem components is reduced and we have a relatively simple assembly, considering that it is enough to introduce the moving core into the roller of the moving support so as to obtain the moving magnetic subsystem. Furthermore, the moving core is devoid of any chamfer, drilled hole or spot facing, thus increasing its polar surface area. Also, the stage of integrating the striker on the moving core is not necessary. For instance the elastic return device is mounted between the moving support and the magnetic frame. This elastic return device consists of, for example, a flexible strip. The positioning of this elastic return device avoids all interaction between the magnetic electric field patterns generated in the air gap. The performance of the magnetic subsystem is thus improved and its assembly in the frame is simplified by its configuration. Following this example, the magnetic subsystem contains a device for guiding the striker by translatory movement. The guiding device contains, for example, an opening in the frame, passing through the striker. Guiding the translatory movement of the striker indirectly results in guiding the translatory movement of the moving support and thereby, the moving mechanical subsystem. No further guiding mechanism is necessary, thus contributing to reduction in the number of parts constituting the magnetic subsystem as per this invention. According to another embodiment, the guiding device contains an opening, maintained in a fixed core and passing through the striker. The magnetic core, for example, is fixed to be integral with the frame. According to an embodiment, the frame is made of magnetic material, constituting an additional fixed magnetic element. As per an embodiment for the magnetic subsystem according to this invention, a part of the frame, facing the polar face of the moving magnetic core, constitutes the fixed additional magnetic element. The magnetic subsystem as per this invention thus offers the advantage of being adaptable to various constraints, both from the structural and the functional aspects. According to one embodiment, the induction coil is a coil with out-of joint turns. The number of turns may be reduced advantageously in as much as the polar surface of the magnetic core is increased. The absence of contact between adjacent turns also obviates the necessity of coating them with electric insulating enamel, thus contributing to reduction of the manufacturing cost of such an induction coil, without however affecting the performance of the magnetic subsystem. According to an embodiment, the induction coil's ends widen tangentially the coil turns. Such a configuration enables to avoid bending operations on these ends and thereby reduces the manufacturing cost of such an induction coil. The present invention finds its application particularly in the domain of electric circuit breakers, incorporating a magnetic subsystem as described above. Accordingly, the present invention relates to a magnetic subsystem for modular electric equipment of the circuit breaker type, comprising an induction coil; a moving magnetic core; a striker moving along with the moving core; an elastic return device required for the displacement of the striker characterised in that the moving core is housed in a moving support, driven by the moving core and integral with the striker. The present invention also relates to an electric circuit-breaker comprising: a fixed contact, to which the first end of the induction coil is connected, a binding post connecting to the subsystem, to which the first end of the induction coil is connected, a magnetic subsystem conforming to one of the claims 1 to 14. Other features and advantages will also emerge from the detailed description given below, without being limited to this, with references to the accompanying drawings as follows:- - Figure 1 is an exploded view of an embodiment for a magnetic subsystem conforming to this invention. - Figure 2 is a sectional view of an embodiment for a magnetic subsystem conforming to this invention. - Figure 3 is an exploded view of another embodiment for a magnetic subsystem conforming to this invention. - Figure 4 is a detail of figure 3. - Figure 5 represents the magnetic subsystem of figure 3, once assembled. - Figure 6 is another embodiment for a magnetic subsystem conforming to this invention. Figure 7 is a sectional view of another embodiment of a magnetic subsystem conforming to this invention. - Figure 8 represents a circuit breaker incorporating a magnetic subsystem • conforming to this invention. The magnetic subsystem, represented for example in figure 1, consists of a magnetic frame (1), made from a magnetic material as well as an induction coil (2) to be mounted length-wise in the frame (1). The frame (1) enables to at least partially channelise the magnetic electric field patterns generated by an electric current passing through the induction coil (2). According to another embodiment, the frame (1) may be non magnetic. The magnetic subsystem also consists of a moving magnetic core (3) made of magnetic material, for example steel. The core (3) has a practically cylindrical form with two polar faces (4) and (5). A striker (6) moving along with the moving core (3) is also provided and it enables to break an electric contact while it moves from an idle position to an active one. An elastic return device is provided in such a manner as required by the displacement of the striker (6). Thus, while the flow of electric current in the induction coil (2) is interrupted, the elastic return device (7a, 7b) brings the striker (6) automatically back to its idle position and the electric contact can be closed once again. A fixed contact (8), to which is connected a first end (2a) of the induction coil (2), is integral with the frame (1). A contact pad (9) is advantageously attached to the fixed contact (8). A binding post (10) for connecting to the magnetic subsystem, to which a second end (2b) of the coil (2) is connected, is also provided. The magnetic subsystem represented in figure (2) has an air gap (11) between the polar face (5) of the moving core (3) and an internal face (12) of the frame (1), with (5) and (12) facing each other. A part of the frame (1) facing the polar face (5) of the moving magnetic core (3) then constitutes a fixed magnetic core. In this embodiment, the air gap (11) partially separates the magnetic core from the magnetic coil (2). The moving core (3) is also simplified in form, which is for example, cylindrical. The binding post (10) extends advantageously over the magnetic part (10a) covering the length of the coil (2) and helps channelise partly the magnetic electric field patterns generated by the induction coil (2). Thus the frame (1) and also the magnetic part, (10a) together delimit a housing in which the magnetic coil (2) is inserted. According to the embodiment represented in figure 7, the magnetic subsystem comprises a fixed magnetic core (3a) integral with the frame (1) and through which the striker (6) passes. The air gap (11) is localised between the polar faces opposite each other, the moving core (3) and the fixed core (3a). The air gap (11) occupies then the inside volume delimited by the magnetic coil (2). The fixed core (3a) is fitted on the frame (1) by any known means, mainly by forced mounting or welding. The moving core (3) is housed in a moving support (13) driven by the above said moving core (3), integral with the striker (6). Thus a moving magnetic subsystem is obtained, moved by the flow of excess current in the induction coil (2). The dimensions of the moving core (3) and the air gap (11) are chosen based on the force necessary for enabling the striker (6) to pull away a moving contact (8a) resting on the contact pad (9) and break the electric circuit in the induction coil (2). Once the electric circuit is broken in the induction coil (2), the elastic return device helps the moving mechanical subsystem, that is, the moving core (3) and the moving support (13), with the striker (6) return to its idle position. It is advantageous to make the moving support (13) and the striker (6) as an integrated unit, for example with plastic material or any other insulating material. The moving support (13) is a cylindrical unit, whose one end terminates in the striker rod (6). The manufacture of such moving support (13) by injection is very simple and its dimensions are chosen in such a manner as to be integral with the moving core (3) by means of a simple fitting operation. Other known technical processes of the gluing type may also be used to make the moving core (3) integral with the moving support (13). The elastic return device is mounted between the moving support (13) and the magnetic frame (1). This elastic return device is for example characterised by a flexible strip (7a) having openings for passage of the positioning plugs (1a), adequate numbers of these are available on the frame (1). In the embodiment shown in figure 2 or 7, it is evident that the striker (6) passes through the opening (1b) maintained in the frame (1). This opening (1b) constitutes a means of producing a translatory movement of the striker (6) and indirectly, a translatory movement of the moving mechanical subsystem, this being connected to the frame (1) through the elastic return device. In the embodiment shown in figure 7, the fixed core (3a) engaged in the opening (1b), serves as a guiding unit for the striker (6). The induction coil (2) advantageously has out-of-joint turns. Considering that the polar face (5) is relatively important and that it should not have any recess, chamfer or bore which may alter the magnetic electric field patterns, the reduction in the number of turns around the moving core (3) helps maintain, rather improve, the performance of the magnetic subsystem. Besides, the separation or the absence of contact between adjacent turns obviates the need for any enamel type of insulation coating on the turns. The ends (2a) and (2b) of the induction coil (2) spread tangentially the turns of the coil (2). The bending operation of these ends (2a, 2b) is eliminated. Thus the cost price of such an induction coil (2) is reduced for more than one reason. The elastic return device may also be made with an elastic strip (7b) integral with the moving support (13), as shown in the example on figures 3 to 5. The elastic strip (7b) extends on the outside of the moving support roller (13) in the form of an outer rim. This then rests on a side face (1a) of the frame (1). During movement of the moving support (13), the elastic strip (7b) is distorted and then resumes its initial form once the electric current circuit is broken in the induction coil (2), bringing it back to its idle position on the striker (6). According to another embodiment of this invention, the magnetic subsystem, as shown in the example on figure (6), the elastic return device consists of an elastic washer (7c) positioned in the air gap (11). The elastic washer (7c) rests on the inner face (12) of the frame (1) and on one of the ends of the moving support (13). During the movement of the moving support (13), the elastic washer (7c) is compressed. Once the electric circuit in the induction coil (2) is broken, this elastic washer (7c) made of plastic or metallic material or foam, resumes its initial position and brings the moving support (13) back to its open position corresponding to the idle position of the striker (6). In another embodiment, the frame (1) is non magnetic and no fixed magnetic core is linked to this frame (1). The movement of the moving core (3) is obtained by means of a given location zone with magnetic electric field patterns of maximum density, towards which it is moved. Such a movement is sufficient to activate the striker (6). Figure (8) represents a partially sectioned view for clarity, of a circuit breaker (15) according to this invention. The circuit breaker (15), incorporating a magnetic subsystem as per this invention, comprises a modular box (16) provided with fasteners (17), for example a support of the rail type of mounting (not shown in the figure). The circuit breaker (15) has an activating unit of the changing lever type (18), helping move the moving contact (8a) between an open and a closed position (refer figure 8) of the electric connection with fixed contact (8). In case of excess current, the striker (6) acts on a mechanical lock (19) known in the trade, which displaces the moving contact (8a) for opening the electric connection with the fixed contact (8). This opening operation breaks the electric circuit between the binding posts (10) of the circuit-breaker and automatically brings the lever (18) to the position corresponding to the separation of fixed contact (8) and moving contact (8a), with the help of the mechanical lock (19). The mechanical lock (19) may be put to action by breaking the circuit, either by means of the striker (6) or a bimetal thermostatic release incorporated in the circuit breaker (15) (not shown in the figures). WE CLAIM: 1. Magnetic subsystem for modular electric equipment of the circuit-breaker type, comprising :- - an induction coil (2); - a moving magnetic core (3); - a striker (6) moving along with the moving core (3); - an elastic return device required for the displacement of the striker (6) characterised in that the moving core (3) is housed in a moving support (13), driven by the moving core (3) and integral with the striker (6). 2. Magnetic subsystem as claimed in claim 1, wherein the moving support (13) and the striker (6) are both made in one integral piece. 3. Magnetic subsystem as claimed in claim 2, wherein the moving support (13) is a cylindrical piece one of whose ends is a rod, which forms part of the striker (6). 4. Magnetic subsystem as claimed in claim 2 or 3, wherein the moving support (13) is made of plastic material. 5. Magnetic subsystem as claimed in claims 1 to 4, wherein it has a guiding device for translatory movement of the striker (6). 6. Magnetic subsystem as claimed in claim 5, wherein the guiding device comprises an opening (1b), which is maintained in a frame (1) and through which a striker (6) passes. 7. Magnetic subsystem as claimed in claim 5, wherein the guiding device comprises an opening (1b), which is maintained in a fixed core (3a) and through which the striker (6) passes. Magnetic subsystem as claimed in claims 6 and 7, wherein the fixed core 3(a) is integral with the frame (1). Magnetic subsystem as claimed in claim 8 or 6, wherein the frame (1) is made of magnetic material constituting an additional fixed magnetic part with respect to the fixed core (3a). Magnetic subsystem as claimed in claim 9, wherein the part of the frame (1), opposite the polar face (5) of the moving magnetic core (3) constitutes an additional fixed magnetic part with respect to the fixed core (3a). Magnetic subsystem as claimed in any one of the claims 1 to 10, wherein by the elastic return device (7a, 7b, 7c) is mounted between the moving support (13) and the magnetic frame (1). . Magnetic subsystem as claimed in claim 11, wherein it comprises an elastic return device, along with a flexible strip (7a). . Magnetic subsystem as claimed in any one of the claims 1 to 12, wherein the induction coil (2) is a coil with out-of-joint turns. Magnetic subsystem as claimed in any one of the claims 1 to 13, wherein the ends (2a, 2b) of the induction coil (2) spread tangentially the turn of the coil. Electric circuit-breaker comprising: - a fixed contact (8, to which the first end (2a) of the induction coil (2) is connected, - a binding post (10) connecting to the subsystem, to which the first end (2b) of the induction coil (2) is connected, - a magnetic subsystem ponforming to one of the claims 1 to 14. . A magnetic subsystem for modular electric equipments, substantially as herein described, particularly with reference to the accompanying drawings. An electrical circuit breaker incorporating a modular subsystem as claimed in any of the claims 1 to 14. Magnetic subsystem for modular electric equipment and electric circuit breaker type, consisting of: - An induction coil (2), - A movable magnetic core (3) - A striker (6) moving along with the movable core (3), - An elastic return device activated by the movement of the striker (6). The movable core (3) is housed in a movable support (13), driven by the movable core (3) and integral with the striker (6).

Documents:

430-KOL-2004-CORRESPONDENCE.pdf

430-KOL-2004-FORM 27.pdf

430-kol-2004-granted-abstract.pdf

430-kol-2004-granted-assignment.pdf

430-kol-2004-granted-claims.pdf

430-kol-2004-granted-correspondence.pdf

430-kol-2004-granted-description (complete).pdf

430-kol-2004-granted-drawings.pdf

430-kol-2004-granted-examination report.pdf

430-kol-2004-granted-form 1.pdf

430-kol-2004-granted-form 18.pdf

430-kol-2004-granted-form 2.pdf

430-kol-2004-granted-form 3.pdf

430-kol-2004-granted-form 5.pdf

430-kol-2004-granted-pa.pdf

430-kol-2004-granted-reply to examination report.pdf

430-kol-2004-granted-specification.pdf

430-kol-2004-granted-translated copy of priority document.pdf