EP2311058B1 - Electromagnetic actuator with flux by-pass - Google Patents

Abstract

Electromagnetic actuator with flux by-pass comprising: a permanent magnet; a ferromagnetic armature; one or two keepers creating at least one gap with the armature and able to move between an open position and a closed position; mechanical return means for returning each keeper to the open position; and at least one electrical conductor capable of generating a magnetic flux in the armature. The magnet, the armature and the keepers are arranged in such a way that the magnet generates lines of flux in two magnetic circuits in parallel, each comprising at least one portion of the armature, a common branch comprising the magnet and one of the two keepers, or a fraction of the keeper separated from said portion of the armature by at least one gap, and in that the conductor or conductors are capable of generating, in at least one additional closed magnetic loop of the armature that includes at least one common branch with said parallel circuits, a flux which is added to the flux created by the magnet in one of the circuits and subtracted therefrom in the other.

Description

The present invention relates to a permanent magnet electromagnetic actuator conventionally comprising a magnetic armature, at least one movable pallet, a spring mechanism and electrical means comprising at least one conductor whose current variations make it possible to vary the flux in the magnetic circuit. to change the balance between the magnetic force and that of the spring. The document US 2004/0027775 describes a device according to the preamble of claim 1.

The object of the invention is to provide an actuator with very high sensitivity, that is to say operating with a minimum value of ampere / revolution generating however at at least one gap a flow variation sufficient to counterbalance the mechanical force and cause the movement of a pallet.

The idea underlying the invention is to work on a flow bypass scheme, the change of the flux at the gap or air gaps being obtained indirectly because of a configuration of the magnetic circuit in which occurs an imbalance of the magnetic reluctances seen by the magnet. In this hypothesis, the conductor (s) capable of generating flow by passing the current through which it travels cooperates with one or more portions of the armature which is (are) closed, and therefore does not have an air gap but at least one equilibrium reluctance. On the other hand, the flow produced has an effect aimed at unbalancing the said reluctances seen by the magnet, which compensates for the imbalance and makes it possible to break - at the level of the gaps concerned by the flow variations - the equilibrium with the mechanical return forces.

For this purpose, the actuator of the invention, more precisely comprising a permanent magnet, a ferromagnetic armature, one or two pallets (s) creating at least one gap with the armature and mobile (s) between at least one position opening and a closed position, the mechanical return means of each pallet in the open position and at least one electrical conductor capable of generating a magnetic flux in the armature, characteristically essential in that the magnet, the armature and the vanes are arranged so that the magnet generates fluxes in two magnetic circuits in parallel each comprising at least a portion of the armature, a common branch comprising magnet and one of the two pallets or a fraction of the pallet separated from said reinforcing portion by at least one air gap, the conductor or conductors being capable of generating, in at least one additional closed magnetic loop of the frame comprising at least a common branch with said circuits in parallel, a flow that adds to the flux created by the magnet in one of the circuits and is subtracted in the other.

The principle of the structure of the invention consists in generating a strong variation of flux on the pallet or pallets with a minimum of ampere-turns in a closed portion of the overall magnetic circuit, thanks to the modification of the balance of the reluctances obtained. in all of said circuit.

According to a possible configuration, the actuator may comprise a single pallet disposed substantially perpendicularly to the magnet or to a branch of the armature comprising the magnet, the closed loop of the armature cooperating with the conductor or conductors being then disposed to the opposite of the pallet with respect to the magnet.

More precisely, the pallet may consist of a rectilinear beam joining two lateral branches of the armature surrounding a central branch comprising the magnet, said branches being interconnected by a portion of the closed loop of the armature.

Alternatively the pallet may be U-shaped whose legs are placed on either side of the central branch comprising the magnet, their free ends forming two air gaps with a portion of the closed loop of the frame.

According to the invention, the closed magnetic loop may either comprise a coil wound around a portion of the closed loop of the armature separate from the parallel magnetic circuits, or surround at least two power supply conductors of an electrical circuit.

The closed loop of the frame can obviously take various forms, for example rectangular, of circular shape etc.

According to a configurational alternative, the actuator of the invention may comprise two vanes whose ends form separate air gaps with the two additional closed magnetic loops arranged at both ends of the common branch of the armature comprising the magnet, said loops surrounding at least two power supply conductors of an electrical circuit.

Various configurations are then possible, for example with a common branch V or U, the magnet forming the base, pallets themselves rectilinear or U etc.

• La figure 1 représente schématiquement une première forme possible d'actionneur pour l'invention, avec une boucle fermée ;
• La figure 2 montre le schéma électromagnétique équivalent à la structure de la figure 1 ;
• La figure 3 montre une variante de la figure 1 dans laquelle la boucle fermée entoure deux conducteurs ;
• La figure 4 illustre une possibilité de configuration en V pour une version à deux boucles fermées ; et
• La figure 5 en montre une vue de côté.

The invention will now be described in more detail, with reference to examples illustrated by the appended figures, for which:

• The figure 1 schematically represents a first possible form of actuator for the invention, with a closed loop;
• The figure 2 shows the electromagnetic pattern equivalent to the structure of the figure 1 ;
• The figure 3 shows a variant of the figure 1 wherein the closed loop surrounds two conductors;
• The figure 4 illustrates a possibility of V configuration for a closed two-loop version; and
• The figure 5 shows a side view.

With reference to the figure 1 , the frame 1 comprises a loop 2 surmounted by two lateral branches 3 and 4 in the middle of which is a permanent magnet 5. A rectilinear palette 6 joins the two branches 3 and 4. The loop 2 is provided with a coil 7 surrounding one of his branches.

Magnetic operation is explained in figure 2 . Without electrical fault, the magnet globally sees two branches of magnetic reluctance in parallel.

It then generates in each branch a magnetic flux such as: $$\begin{array}{l}\mathrm{RPAL}\mathrm{1}\left(\mathrm{phi}\mathrm{1}\right)\mathrm{x\; phi}\mathrm{1}+\mathrm{Rent}\mathrm{1}\left(\mathrm{phi}\mathrm{1}\right)\mathrm{x\; phi}\mathrm{1}+\mathrm{Rmat\_haut}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\\ +\mathrm{Rmat\_bas}\left(\mathrm{phi}\mathrm{1}+\mathrm{Phi}\mathrm{2}\right)\mathrm{x}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)+\mathrm{R}\mathrm{1}\left(\mathrm{phi}\mathrm{1}\right)\mathrm{x\; phi}\mathrm{1}=\\ \mathrm{RPAL}\mathrm{2}\left(\mathrm{phi}\mathrm{2}\right)\mathrm{x\; phi}\mathrm{2}+\mathrm{Rent}\mathrm{2}\left(\mathrm{phi}\mathrm{2}\right)\mathrm{x\; phi}\mathrm{2}+\mathrm{Rmat\_haut}<figure-callout\; id="1"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\\ \left(\mathrm{<figure-callout\; id="1"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{1}+\mathrm{<figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}\right)+\mathrm{Rmat\_bas}<figure-callout\; id="1"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}<figure-callout\; id="1"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{1}+\mathrm{<figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}\right)+\mathrm{R}\mathrm{2}\left(\mathrm{phi}\mathrm{2}\right)\mathrm{x\; phi}\mathrm{2}\end{array}$$

With phi1 + phi2 = flux generated by the magnet (magnetic leakage near) In this case, the magnet balances the value of the fluxes to balance the value of the reluctances.

Material reluctances such as Rpal, R1 and R2 are nonlinear and saturable. The Rmat_haut and Rmat_bas reluctances may represent a gap and / or a saturable magnetic material.

The Rent1 and Rent2 reluctances represent the equivalent gap between the pallet and the armature.

• Soit diminuer R2 et augmenter R1
• Soit diminuer R1 et augmenter R2

When an electrical fault appears, the coil generates a magnetic flux in the closed loop Rbas, R1 and R2. This has the effect of:

• Either decrease R2 and increase R1
• Either decrease R1 and increase R2

Indeed, in the case where the flow of the coil is in the direction of that of the figure 2 we have the following relation: $$\begin{array}{l}\mathrm{RPAL}\mathrm{1}\left(\mathrm{phi}\mathrm{1}\right)\mathrm{x\; phi}\mathrm{1}+\mathrm{Rent}\mathrm{1}\left(\mathrm{phi}\mathrm{1}\right)\mathrm{x\; phi}\mathrm{1}+\mathrm{Rmat\_haut}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\\ \left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)+\mathrm{Rmat\_bas}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\left(\mathrm{phi}\mathrm{1}+\mathrm{phi}\mathrm{2}+\mathrm{phi\_bob}\right)+\mathrm{R}\mathrm{1}(\mathrm{phi}\mathrm{1}-\\ \mathrm{phi\_bob})\mathrm{x}\left(\mathrm{phi}\mathrm{1}-\mathrm{phi\_bob}\right)=\mathrm{<figure-callout\; id="2"\; label="RPAL\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">RPAL\; </figure-callout>}\mathrm{2}\left(\mathrm{phi}\mathrm{2}\right)\mathrm{x\; <figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}+\mathrm{Rent}\mathrm{2}\left(\mathrm{phi}\mathrm{2}\right)\mathrm{x\; <figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}+\\ \mathrm{Rmat\_haut}<figure-callout\; id="1"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\left(\mathrm{<figure-callout\; id="1"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{1}+\mathrm{<figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}\right)+\mathrm{Rmat\_bas}<figure-callout\; id="1"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{1}+\mathrm{phi}\mathrm{2}\right)\mathrm{x}\left(\mathrm{<figure-callout\; id="1"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{1}+\mathrm{<figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}\right)+\\ \mathrm{R}\mathrm{2}<figure-callout\; id="2"\; label="\; phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">\; </figure-callout>\left(\mathrm{phi}\right)\left(\mathrm{2}+\mathrm{phi\_bob}\right)\mathrm{x}\left(\mathrm{<figure-callout\; id="2"\; label="phi\; "\; filenames="imgf0001.png,imgf0003.png"\; state="\{\{state\}\}">phi\; </figure-callout>}\mathrm{2}+\mathrm{phi\_bob}\right)\end{array}$$

The coil flux tends to decrease R1 (phi) x phi and to increase R2 (phi) x phi. Seen by the magnet, the previous balance is changed. It therefore generates more magnetic flux on one side than the other to compensate for this imbalance (in the example, we will have phi1 which will increase and phi2 which will decrease). He is thus creates a variation of magnetic flux and therefore of magnetic force on the polar surfaces.

The above demonstration is performed for one direction of the current. It can also be for the other.

The advantage of this solution lies in the fact that with little amperes, the structure of the invention generates a large variation of flux on the pallet by modifying the balance of the reluctances.

Different types of structure can apply this principle, including those of the following figures. So, in figure 3 , the closed loop 2 'is of circular shape, while the pallet 6' is U-shaped, integrating the lateral branches 3 'and 4'. In this configuration, the supply conductors are directly surrounded by the actuator of the invention which groups together both the current unbalance detection torus, in this case the loop 2 ', and the "relay" portion constituted by the upper part of the structure 1 'of the invention.

The configurations 10, 10 'of the following figures have two closed loops, but they operate according to the same principle. In figure 4 the common branch 11 comprises a central magnet 12 and two end loops 13, 13 '. Two pallets 14, 14 'have polar surfaces 15, 15' and 16, 16 'facing opposite sides 17, 17' and 18, 18 'of the closed loops 13, 13'. Two supply conductors pass through said loops 13, 13 '. It is the same conductors in the two loops 13, 13 ', because the structure is in V, the representation is a view from above. A side view is shown in figure 5 .

The operation is based on the same principle, the flows 21, 21 '(in dotted lines) created in the two loops 13, 13' adding to the flow 22 '(solid line) of one of the circuits in parallel and evading flow 22 from the other.

Claims (9)

1. Electromagnetic flux bypass actuator with a permanent magnet (5), a ferromagnetic armature (1), one or two keeper(s) (6) creating at least one air gap with the armature (1) and mobile between an open position and a closed position, a mechanical means of returning each keeper (6) to the open position and at least one electrical conductor capable of generating a magnetic flux in the armature (1), the magnet (5), the armature (1) and the keepers (6) being arranged so that the magnet (5) generates flux in two parallel magnetic circuits each of which contain at least one section (3, 4) of the armature (1), a common branch containing the magnet (5) and one of the two keepers (6) or a part of the keeper (6) separated from the said section (3, 4) of the armature by at least one air gap, characterized in that the conductor(s) are capable of generating, in at least one additional magnetic closed loop (2) on the armature (1) and having at least one common branch with the said parallel circuits, a flux which adds to the flux created by the magnet (5) in one of the circuits and is subtracted from the other.
2. Electromagnetic actuator according to the preceding claim, characterized in that it contains a single keeper (6) positioned more or less perpendicular to the magnet (5) or to one branch (3, 4) of the armature (1) containing the magnet (5), the closed-loop (2) on the armature (1) working with the conductor(s) being positioned opposite to the keeper (6) in relation to the magnet (5).
3. Electromagnetic actuator according to the preceding claim, characterized in that the keeper (6) consists of a straight beam joining two lateral branches (3, 4) of the armature (1) surrounding a central branch containing the magnet (5), the said branches (3, 4) being linked together by a section of the closed loop (2) on the armature (1).
4. Electromagnetic actuator according to the preceding claim, characterized in that the keeper (6') is in the form of a U of which the legs (3', 4') are placed on either side of the central branch containing the magnet (5), their free ends forming two air gaps with a section of the closed loop (2') on the armature (1).
5. Electromagnetic actuator according to one of claims 2 to 4, characterized in that the closed loop (2) on the armature (1) contains a coil (7) wrapped around one part of the said closed loop (2) separate from the parallel magnetic circuits.
6. Electromagnetic actuator according to one of claims 2 to 4, characterized in that the additional magnetic loop (2) wraps around at least two supply conductors of an electrical circuit.
7. Electromagnetic actuator according to claim 1, characterized in that it contains two keepers (14, 14') of which the ends form separate gaps with the two additional magnetic closed loops (13, 13') positioned at both ends of the common branch (11) of the armature (1) containing the magnet (12), the said loops (13, 13') wrapping around at least two supply conductors of an electrical circuit.
8. Electromagnetic actuator according to the preceding claim, characterized in that the common branch (11) is in a V or a U, the magnet (12) forming the base.
9. Electromagnetic actuator according to one of claims 7 and 8, characterized in that the keepers (14, 14') are straight or in a U.

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