FR2807871A1 - Low voltage electromagnetic switching mechanism having fixed body/central hub and outer coil continuous current fed and switched from parallel/series using command from palette contact carriers. - Google Patents

Abstract

The electromagnet switch apparatus has a fixed body (10) and a central hub (11) with an outer coil (12) with two windings fed by continuous current. There is a palette (20) with moving contact carriers (21). The two windings are identical and connected in parallel in the contact carrier open position and series in the closed position using a switching mechanism in the isolating support. A mechanical command (25,26) activates the switching.

Description

The present invention relates to an electromagnet, in particular a direct current electromagnet, intended for a low-voltage power switch device, such as a contactor or a circuit breaker contact, comprising a movable armature and fixed cylinder head, which carries two identical windings connected either in series or in parallel depending on the position of the movable frame relative to the fixed cylinder head.

Many electromagnets have a movable metallic armature which is capable of carrying out closing and opening movements between a closed position and an open position. Generally, the closing movement is caused by the force of attraction resulting from the circulation of an inrush current in a coil located on the fixed cylinder head and the opening movement is caused by a return spring in the absence of current in the coil.

A direct current electromagnet generally delivers a very large motor force when it is closed, which can make it difficult to open. Also, to alleviate this problem therefore facilitate the opening of the contacts, one can for example increase the restoring force, or use a larger anti-remanent air gap. One can also seek to reduce the current consumed in the phase of maintaining the closed state.

For this, it is known to use two windings on the one hand to effect the closing movement and on the other hand to maintain the movable armature in the closed position. In certain cases, as indicated for example in document EP 627753, a first winding is activated during a first call phase corresponding to the closing movement of the movable frame, in order to obtain a sufficient attractive force, then the two windings are simultaneously activated during a second phase of calling the movable armature, in order to minimize the current consumed. However, solutions can entail additional means such as an electronic circuit to determine the switching instant between the two phases, thus penalizing production costs. In addition, it is not always easy to reliably and repetitively control this switching instant, in particular because of the evolution of mechanical friction, of the value of the inrush current in the coil.

This is why the invention aims to design in the simplest and most economical way an electromagnet supplied with direct current or rectified current, having the capacity to consume a holding current lower than the inrush current. necessary for the closing movement of the movable frame, the switching between the call and hold phases being made during the movement of the movable frame with respect to the fixed cylinder head.

This is why the invention describes an electromagnet of a switching device comprising a fixed yoke having a central core surrounded by a coil made up of an insulating support carrying two windings supplied with direct current, and a metal movable armature, in the form of pallet, integral with a movable contact carrier made of insulating material, having at least one flat pole face capable of effecting a closing and opening movement between a closed position and an open position as a function of the current flowing in the windings. It is characterized by the fact that the two windings are identical, are connected in parallel when the movable frame is in the open position and during a first initial part of the closing movement of the movable frame and are connected in series when the movable frame is in the closed position and during a first initial part of the opening movement of the movable armature, the change of the connection mode of the two windings being effected by means of a switching device installed directly on the insulating support of the coil and actuates mechanically by a control member located on the movable frame. The advantage of having two windings connected in series in the holding phase and in parallel in the inrush phase, is that this makes it possible to increase the inrush current compared to a single winding, because one never reaches the established phase of the call phase, switching occurring before.

The switching device consists of two opening contacts respectively connected to each end of the two windings and by a diode wired in series between the two windings, so that when the two contacts are in a nonconductive state 0, both windings are connected in series and when the two contacts are in a 1 conductor state, the two windings are connected in parallel. The advantage of installing this device directly on the insulating support of the coil, is to allow a reduction in the cost of the tolerances of the device, while offering the possibility of a direct connection windings on the contacts during the operation winding. Furthermore, the mobi armature control member is constituted by two lugs belonging to the movable contact carrier and passing through the movable pallet via two transverse openings, capable of switching the two contacts of the switching device during the movements of the armature mobile. The lugs therefore do not require any additional part since they are directly integrated into the movable contact carrier, generally produced by plastic molding. This simple assembly offers the desired functionality as will be detailed later.

Other advantages and characteristics of the invention will emerge from the detailed description which follows, illustrated by the appended drawings in which - FIG. 1 represents a general view of an electromagnet according to the invention, - FIG. 2 shows a section along an axis XX of an exemplary embodiment of the electromagnet switching device in the open position, - Figure 3 shows the same device as in Figure 2, but in the closed position, - Figure 4 details a mode of the electrical diagram of the switching device, - Figure 5 is a variant of Figure 4, - Figure 6 shows in top view the details of the windings and the switching device of the electromagnet.

With reference to FIG. 1, a low voltage power switch device, such as a contactor or a contactor / circuit breaker, comprises an electromagnet composed of a fixed yoke 10 having two lateral wings 13,14 parallel to a central core 11 , which can advantageously be of cylindrical shape, the ends of the central core 11 and of the two lateral wings 13, 14 forming a planar external face 10a. The central core 11 is surrounded by a coil 12 consisting of an insulating support 15, which can advantageously be cylindrical, carrying two windings S1, S2.

Each of the two windings S1, S2 consists of a winding produced from a conductive wire which is enamelled to ensure its insulation, each conductive wire having a first end called respectively a1, b1 and a second end called respectively a2, b2 . As indicated in FIG. 6, these two wires are simultaneously wound side by side and homogeneously around the insulating support 15, several superposed layers so as to form the coil 12. This embodiment makes it possible to obtain that the resistance value X , the value of self and the magnetic behavior of the two windings S1, S2 are substantially identical.

The electromagnet also comprises a movable metallic armature 20, in the form of a pallet I, integral with a movable contact carrier 21 made of insulating material, having at least planar pole face 20a. The movable armature 20 performs a closing movement F and opening O between a closed position and an open position as a direct current function I flowing in the coil 12. In the embodiment represented in FIGS. 1, 2 and 3, these movements are rectilinear. In the open position, flat faces 10a and 20a are spaced apart from one another as indicated in the figure in the closed position, also called holding phase, the flat faces 10a and are brought closer to each other as indicated in FIG. 3 The closing movement F, also called the call phase, corresponds to the passage from the open position to the closed position and the opening movement O corresponds to the passage from the closed position to the open position.

The electromagnet has a switching device 19 making it possible to connect the windings S1, S2 either in series or in parallel. According to FIG. 4, this switching device 19 consists of two opening contacts K1, K2 and a diode D, located on the insulating support 15 of the coil 12. The contacts K1, K2 are each formed by a supply of fixed current and a flexible conductive strip, respectively 27.28, which simultaneously ensures the passage of the current and the contact pressure. The contacts K1, K2 are located on either side of the central core 11 and are either in the nonconductive state 0, or in the conductive state 1. They are mechanically actuated a control member 25, 26 secured to the movable frame 20 and positioned in prominence of the surface 20a. Thus, depending on the position of the movable frame, the control member 25,26 may or may not press on the flexible conductive blade 27,28 contacts K1, K2 thus causing passage to the state 0 or 1. The contact K1 is connected electrically between the first ends a1 and a2 of the windings S1 the contact K2 is electrically connected between the second ends b1 and windings S1, S2. The diode D is wired in series between the windings S1, S2, that is to say between the ends a2 and b1, the direction of the diode D authorizing passage of the current only from b1 to a2. The current I then arrives in the device 19 the end a1 and leaves through the end b2. Similarly, it could have been envisaged that the diode D would be wired between the ends a1 b2, the current I then arriving in the device 19 by the end a2 and coming out through the end b1.

When the contacts K1, K2 are in the conducting 1 state, the direct current I arriving in the coil separates between the following two paths:, S1, b1, K2, b2 on the one hand and, K1, a2, S2, b2 on the other hand. The two windings, S2 are therefore mounted in parallel since the diode D prevents the current passage from a2 to b1. As the value X of the resistances of the two windings S1, S2 is substantially identical, the equivalent resistance of the coil 12 is equal to XI2. When the contacts K1, K2 are in the nonconductive state 0, the direct current I arriving in the coil takes the following path: a1, S1, b1, D, a2, S2, b2. The two windings S1, S2 are therefore connected in series since the diode D authorizes the passage of the current from b1 to a2. As the value X of the resistances of the two windings S1, S2 is substantially identical, the equivalent resistance of the coil 12 is then equal to 2 * X. Thus the equivalent resistance of the coil 12 varies from a ratio of 1 to 4 depending on the state of the contacts K1, K2.

According to a variant presented in FIG. 5, it is possible to add a resistor R series with the diode D, between the ends a2 and b1 so as to be able to adjust the current consumption during the holding phase as well as the drop-out voltage l electromagnet, when the movable armature is in the closed position.

In the embodiment presented, the control member of the movable armature 20 is embodied by two lugs 25, 26 integrated in the movable contact carrier 21. For example, the movable contact carrier 21 and the two lugs can be molded together so as to avoid the production of an additional part. The two pins 25 and 26, positioned on either side of the central core 11 in correspondence with the locations of the contacts K1, K2, pass through two transverse orifices 20b, 20c formed in the movable frame 20 so as to come into prominence from the flat surface 20a. They can thus press each opening contact K1 and K2 respectively. The size of the pins 25, 26 is adjusted to have the operation described in the following paragraphs. When the movable armature 20 is in the open position, the pins 25 are separated from the contacts K1, K2. These are then in state 1 and the windings S2 are connected in parallel resulting in an equivalent resistance of the coil low and equal to XI2. Therefore, for a given supply voltage, the available inrush current will be greater, which will facilitate the closing movement F.

During the closing movement F of the movable armature 20, preferably at the end of the closing movement F, the pins 25, 26 will press on flexible conductive blade 27, 28 of the contacts K1, K2, which will cause the switching of these in state 0 and the passage of the windings S1, S2 to a serial connection. In this configuration, the equivalent resistance of the coil increases passes to a value equal to 2 * X so that, for a given voltage, the current consumption will decrease.

As long as the movable armature 20 remains in the closed position, lugs 25, 26 press on the contacts K1, K2 which remain in state 1, and the windings S1, S2 remain connected in series, which limits the current consumption throughout the holding phase and which therefore the return force necessary to cause the opening movement O, materialized by a return spring, for example.

During the opening movement O of the movable armature 20, preferably at the start of the opening movement O, the pins 25, 26 will move away from the flexible conducting blade 27, 28 from the contacts K1, K2, which will cause the return of these to state 1 as well as the return of the windings S1, S2 to a parallel connection.

An electromagnet is thus obtained which has the capacity to consume a low current during the holding phase, while retaining the capacity to provide sufficient inrush current necessary to initiate the closing movement of the movable armature.

It is not necessary to require that the contacts and K2 switch at exactly the same time since a rapid analysis diagram shown in FIG. 4 easily shows that if, during a transient phase, K1 and K2 are in different states, then the equivalent resistance of the coil will be equal to X, that is to say the resistance of either S1 or S2, halfway between the values XI2 and 2 * X previously described.

Furthermore, the direct current I flowing in the coil can come from a rectifier member placed upstream, such as a diode bridge, on the one hand to ensure conversion from alternative to direct, in order to adapt to power supply. electromagnet alternately, and on the other hand to avoid polarization the electromagnet continuously.

The invention is not limited to the embodiment described above by way of example and one can imagine variants and improvements in detail and even envisage the use of equivalent means, without departing from the scope of the invention.

Claims (8)

1. Electromagnet of a switching device comprising a fixed yoke (10) having a central core (11) surrounded by a coil (12) consisting of an insulating support (15) carrying two windings (S1, S2) supplied with direct current , and metallic movable frame (20), in the form of a pallet, integral with a movable contact carrier (21) made of insulating material, having at least one planar pole face (20a) and capable of effecting a closing movement (F) and opening between a closed position and an open position depending on the current flowing in the windings (S1, S2), characterized in that the two windings (S1, S2) are identical, are connected in parallel when the armature mobile (20) is in the open position and are connected in series when the mobile armature (20) is in the closed position, the change of the connection mode of the two windings (S1, S2) being effected by means of a switching device (19) located on the supp ort insulator (15) of the coil (12) and mechanically actuated by a control member (25,26) located on the movable frame (20). 2. Electromagnet according to claim 1, characterized in that the passage of connection in series to the parallel connection of the two windings, S2) takes place during the opening movement (O) of the movable armature (20) and the passage from the parallel connection to the series connection two windings (S1, S2) takes place during the closing movement of the movable frame (20). 3. Electromagnet according to claim 2, characterized in that the switching device (19) consists of two opening contacts (K1, K2) respectively connected between the first ends (a1, a2) and between the second ends (b1 , b2) of the two windings (S1, S2) and by a diode (D) wired in series between the two windings (S1, S2), so that when the two contacts (K1, K2) are in a nonconductive state 0 , the two windings (S1, S2) are connected in series and when the two contacts (K1, K2) are in a 1 conductor state, the two windings (S1, S2) are connected in parallel. 4. Electromagnet according to claim 3, characterized in that the switching device (19) also comprises a resistor (R) wired in series with the diode (D) between the two windings (S1, S2). 5. Electromagnet according to claim 3, characterized in that the control member of the movable armature (20) consists of two lugs (25,26) belonging to the movable contact carrier (21) and passing through the armature mobile (20) via two transverse orifices (20b, 20c), so as to switch the two opening contacts (K1, K2) during the closing (F) and opening (O) movements of the mobile frame (20 ). 6. Electromagnet according to claim 2, characterized in that the central core (11) of the fixed yoke (10) is of cylindrical shape. 7. Electromagnet according to one of the preceding claims, characterized in that each of the two windings consists of a coil, S2) produced from an enamelled conductive wire, these two wires being simultaneously wound side by side, so homogeneous and on several layers superimposed around the insulating support (15) so that the resistance, self and magnetic behavior values of the two windings (S1, S2) are substantially identical. 8. Power switch device characterized in that it is equipped with an electromagnet according to any one of the preceding claims.