EP0174238B1 - Monostably or bistably functioning polarised electromagnet - Google Patents

Description

• une bobine apte à être alimentée en courant continu,
• un noyau magnétisable qui est mobile entre deux positions extrêmes longitudinales alternativement occupées grâce à un glissement à l'intérieur de la carcasse de cette bobine, et qui présente deux épanouissements polaires externes opposés s'étendant transversalement par rapport à l'axe de la bobine,
• une culasse fixe présentant axialement, de part et d'autre de chaque épanouissement une paire de prolongements polaires ayant des polarités magnétiques opposées qui leur sont conférées par des moyens magnétiques permanents placés entre eux et orientés de façon que leurs axes magnétiques soient parallèles au dit axe,

The invention relates to a polarized electromagnet comprising:

• a coil capable of being supplied with direct current,
• a magnetizable core which is movable between two extreme longitudinal positions alternately occupied by virtue of a sliding inside the carcass of this coil, and which has two opposite external pole shoes extending transversely with respect to the axis of the coil,
• a fixed cylinder head having axially, on either side of each blooming, a pair of polar extensions having opposite magnetic polarities which are given to them by permanent magnetic means placed between them and oriented so that their magnetic axes are parallel to said axis ,

the said bloomings coming in cooperation with these extensions so that, for each of the two extreme positions, the magnetic flux sent by these magnetic means through the core is in the opposite direction.

These electromagnets are of great interest for actuating relay or contactor switches where good sensitivity and / or current savings are desired.

An electromagnet having the structure defined above is, for example, known from patent FR-A-1 603 300 where it is applied to a polarized relay effecting the switching of low currents.

In such a polarized relay, the use of a permanent magnet of annular shape and that of a cylindrical core, at the ends of which are concentrically associated two parallel discs, provides a symmetry of the attractions and magnetic repulsions which is reflected in parallel on the sliding of the core inside the coil; this relay however has the drawback of requiring the use of two permanent magnets to magnetize the three separate parts constituting with them the fixed yoke of the relay. In addition, the lateral and completely eccentric position of the magnets which gives the whole a flat shape of small thickness, defines proportions which are difficult to use in certain applications. In this known relay, the use of two magnets and three parts was made necessary by the fact that these parts play an accessory role which is that of participating with the core in the constitution of a switch for low currents; To this end, the permanent magnets use insulating ceramics to establish galvanic isolation between the three parts.

The invention proposes to provide this known relay with improvements aimed at simplifying its structure when the core is associated directly or indirectly with a separate switch requiring, for its switching, the exercise of a higher force, while retaining the advantages which it can enjoy, relative to the generation of the perfectly concentric call forces to the coil.

According to the invention the aim is achieved thanks to the fact that two pairs of extensions, of the same first magnetic sign, placed symmetrically with respect to the axis of the coil form part of the same first piece of rectangular flow pipe surrounding a second piece of flow channeling which connects two other pairs of symmetrical extensions having signs opposite to the first and which surrounds a coil whose carcass is substantially crossed by the magnetic axes of permanent magnets arranged at the same axial level between branches cross flow channeling.

• Les figures 1 et 2 représentent en perspectives deux électro-aimants selon l'invention, ne se différenciant l'un et l'autre que par les dispositions relatives des deux pièces de canalisation de flux.
• La figure 3 montre une vue en élévation de l'électro-aimant selon la figure 1.
• La figure 4 illustre, dans une demi-vue coupée en élévation, un électro-aimant présentant la constitution générale visible à la figure 1, mais où des premières mesures particulières sont prises pour lui conférer un caractère monostable.
• La figure 5 montre dans une vue en perspective avec arrachement au quart, un électro-aimant ayant une constitution voisine de celle visible à la figure 1, mais où des secondes mesures particulières sont prises pour lui conférer un caractère monostable.
• Les figures 6, 7, 8 représentent, dans une vue en élévation coupée par un plan axial, une vue de côté, et une vue de dessus en demi-coupe, un électro-aimant dans lequel sont précisés des moyens d'assemblage de ses différents organes; et
• La figure 9 montre, dans une demi-vue en élévation, une pièce moulée servant de carcasse de bobine, de support pour ses bornes, et de moyen d'assemblage avec le circuit magnétique fixe.

Other particularities of the invention aimed at obtaining a monostable operation respectively that of an apparatus easy to assemble, as well as alternative embodiments, will be better understood on reading the description below, with reference to annexed drawings, in which:

• Figures 1 and 2 show in perspective two electromagnets according to the invention, differing from each other only by the relative arrangements of the two pieces of flow pipe.
• FIG. 3 shows an elevation view of the electromagnet according to FIG. 1.
• Figure 4 illustrates, in a half-view cut in elevation, an electromagnet having the general constitution visible in Figure 1, but where first specific measures are taken to give it a monostable character.
• FIG. 5 shows in a perspective view with a cutaway to the quarter, an electromagnet having a constitution close to that visible in FIG. 1, but where second particular measures are taken to give it a monostable character.
• Figures 6, 7, 8 show, in an elevational view cut by an axial plane, a side view, and a top view in half section, an electromagnet in which are specified means for assembling its different organs; and
• FIG. 9 shows, in a half-view in elevation, a molded part serving as a coil carcass, a support for its terminals, and a means of assembly with the fixed magnetic circuit.

Positions of elements of the electromagnet 1 represented in FIG. 1, being defined with respect to an axis of symmetry, this has been represented by XX ′ which also constitutes the longitudinal axis of the internal length 4 of a carcass 2 receiving a coil 3; in this long slide, between two opposite extreme positions, a magnetizable core 5, two ends 6 and 7 of which are partially visible in the figure; the end 6, which protrudes from the cheek 15 of the carcass receives a first magnetizable pallet 8 having two external and symmetrical transverse polar openings 9, 10, while a second magnetizable pallet 11, having two external transverse and symmetrical polar openings 12 , 13, is placed on the core between a cheek 14 of the carcass 2 and the end 7, the latter being for example used to perform the control of a switch not shown; the apparatus would not be changed if the core 5 instead of stopping at the level of the second pallet were extended by an extension to carry out a mechanical control. The core and its two pallets constitute the moving part of the electromagnet and it is clear that the distance separating the two pallets allows their longitudinal displacement between the two opposite extreme positions.

In one of the extreme positions, the pallet 11 rests on an external transverse branch 16 belonging to a first piece of flow pipe 17 in the form of a rectangular frame, while the pallet 8 rests on an internal transverse branch 18 of a second piece flow channel in the form of a frame 19 which is surrounded in parallel by the first and which in turn surrounds the carcass of the coil. It can be seen in the figure that another internal branch 20 is placed opposite the internal branch 18 of the frame 19 and that another internal branch 21 of this frame is placed opposite the external branches 20 respectively 16, so that each pallet is placed between two parallel branches. These branches constitute pairs of transverse polar extensions 20a, 20b respectively 16a, 16b and 18a, 18b respectively 21a, 21b as will appear in FIG. 3.

It goes without saying that, at least the internal branches, and respectively an external branch have axial openings, not shown so as not to weigh down the figure, in order to allow the passage of the core, respectively of the extension 7.

Two permanent magnets 22 and 23 are placed symmetrically with respect to the axis XX 'between the arms 20 and 18 so that their magnetic poles of the same sign are applied against the same arm and their axis of magnetization NS, N'S', which are both parallel to the axis, substantially pass through the carcass of the coil. This results in a reduction in size and a difference in the length of iron which the flux of the magnet must travel to circulate towards the faces 18, 20 on the one hand and 16, 21 on the other hand.

The two internal branches therefore have the same magnetic polarity of a certain sign, while the two external branches in turn have the same magnetic polarity of sign opposite to the previous one.

It is observed that the device which has just been described has two stable states, defined by the extreme positions of the core, for which, in the absence of excitation of the coil, the core can be crossed by two flows of opposite direction which are supplied by the permanent magnets and which are transmitted alternately by the flow pipe parts. In the second stable state opposite to that of FIG. 1, the pallet 8 passes between the magnets and is applied to the branch 20, while the pallet 11 is applied to the branch 21.

When a direct (or rectified) current of suitable direction is sent into the coil by its two terminals 24, 24 ', the control flow developed by the latter will oppose the permanent flow passing through the core; if this control flow is of sufficient intensity, the core will move axially to take an extreme opposite position.

It is clear that identical operation will be obtained if two other magnets, such as the magnets 22, 23 are placed, in an analogous manner, between the branches 16 and 21 so that their fluxes are additive; however in this case the lengths of iron to be crossed are the same. We also see that the operation remains the same if we rotate, for example, the flow pipe part 19 'by a quarter turn relative to the part 17 and around the axis XX', see figure 2.

We also understand that the permanent flow can still be channeled if one of the partitions 25 or 26 or 27 or 28 must be removed for specific reasons or reduced in section provided that one of them remains to connect, in each frame, the lateral branches which form transverse extensions necessary for the establishment of a flow through the openings of the pallets, and then of the core.

In the embodiment illustrated in FIG. 4, where the parts having the same functions bear the same references, an extension 30 of the core carries a third pallet 31 external to the frame 17 which is distant from the branch 20 for a rest position R where the core is moved to the left and which is pressed there for the opposite extreme working position T shown in this figure, while the pallet 8 does not reach the branch 18. It is clear that for this latter position a low reluctance magnetic circuit (comprising the branch 18, the pallet 8, the extension 30, the pallet 31 and the branch 20) will be placed in parallel with a circuit comprising the branch 18, the core 5, the pallet 11 and the external partitions 27, 28 of the flow channeling part 17 and will thus bypass the flow developed by the permanent magnets, so that the forces of attraction exerted on the pallets for this position will no longer have the same intensity if phenomena saturation es appear for example in branch 18. As a result, upon the disappearance in the coil, of the excitation current which was necessary to bring the paddles in this position T, attractions of opposite directions can be exerted without effect of remanence between the pallets and the branches 20, respectively 21 to bring the movable armature constituted by the set of parts 5, 8, 11 to the rest position R.

The operation of this electromagnet therefore has a monostable characteristic which can advantageously be used for controlling devices of the relay or contactor type.

In a variant of monostable electromagnet visible in FIG. 5, a low parallel reluctance could also be provided by a third pallet 33, placed on an extension 34 of the core 5 ′ situated between the branches 16 ′, 21 ′ so as to place themselves in the plane of the branch 21 'through a slightly larger opening 35 of the latter while the pallet 11' is itself placed outside the branch 16 '. This variant however causes the appearance of transverse forces of attraction on the pallet 33.

In the other position, the magnetic circuit is closed by contacting the vanes 8 ', 33 against the branches 18' and 16 'respectively.

Finally, one can also add to the core, an assistance spring such as 36 to provide an axial force F capable of improving the monostable nature of the device.

An exemplary embodiment of the electromagnet, according to the invention which is visible in Figures 6, 7, 8, and whose implementation can be extended to any of the embodiments presented, has been more particularly adapted to that of FIG. 1.

This example particularly uses a synthetic molded part 70 playing the role of the coil carcass and providing association means capable of firmly applying the pole faces of the permanent magnets against the branches of the flux-conducting parts.

The carcass 40 of the coil 3 has a bore 42, the ends of which are adjusted to guide the core 43, and two transverse cheeks 44, 45. One of these cheeks 45 may have a projection of low height 46 to ensure its centering in an opening 47 of the internal flow guide part 48, while the cheek 44 of generally rectangular shape has at each of its four vertices an elastic longitudinal column, two of which 49, 50 are visible in FIG. 6.

These columns which embrace at their base 51, 52 the internal branch 53, and can center this in relation to the latter thanks to notches such as 54, see also FIG. 7, have at their respective ends a hook such as 55 or 56 which extends beyond the external flow guide branch 57.

The permanent magnets 58, 59 which are placed between these parallel branches are kept in firm contact with them, thanks to a longitudinal force developed by the columns between the hooks and the outer surface 60 of the cheek 44; these same columns, which limit a centrifugal radial movement of the magnets, may include portions of lengths such as 61 for operating lateral guidance of the magnets, see also FIG. 8.

A complementary holding of the magnets intended to prevent their displacement towards the central axis, as well as to provide an angular guidance of the position of the pallets 67, 68 can be ensured by an annex guide piece 62, see FIG. 6, which is placed on one or other of the branches 57 or 53 and has columns or walls parallel to the axis such as those shown at 63 in Figure 3. In the embodiment shown, where the part 62 is made integral of the branch 57 these posts which pass through the openings 64, 64 'of the external branch 57, see FIG. 7, are part of the same plate 65 pierced with an opening to allow the passage of an extension 66 of the core provided for transmit movements.

If this extension is coupled to a contact carrier whose movements are angularly guided and if the branches 53, 57 carry, facing the polar surfaces, magnets, flat depressions preventing their movement towards the axis, we can dispense with '' use annex 62.

In FIGS. 6 to 8, the proportions of the travel of the pallets relative to the other dimensions have not been respected, in order to ventilate the design and to make the structural details more visible.

• la pièce 70 est d'abord munie de son noyau et de ses palettes, celles-ci étant par exemple rivées ou emmanchées à force sur le noyau;
• la carcasse de bobine est ensuite remplie de fil, puis ses extrémité sont raccordées aux bornes prévues à cet effet; pendant cette opération, le maintien de la pièce 70 sur la machine à bobiner est avantageusement opéré grâce aux crochets 55, 57;
• la pièce 70 est ensuite introduite latéralement dans la pièce de guidage de flux interne 71 et du côté G ou manque l'une des parois longitudinales; cette introduction est facilitée par exemple grâce à des entailles 72, 73 pratiquées sur les branches internes, dans le prolongement des ouvertures de passage 72', 73' qui sont traversées par le noyau 43;
• l'ensemble de la pièce 70 et de la pièce 71 est ensuite engagé, en travers, voir direction A figure 6, vers la branche externe 57 de la pièce de guidage de flux 71 et munie de ses aimants; cet engagement peut être facilité par une entaille latérale 75 de la branche 57 assurant au prolongement 66 un passage plus aisé, voir figure 7;
• après mise en alignement coaxial des deux pièces 74 et 71 cette dernière est poussée axialement pour que s'effectue l'accouplement des crochets 55, 57 avec les bords de la branche externe 57;
• la pièce 62 est, le cas échéant, mise en place.

The assembly of this electromagnet is carried out as follows:

• the part 70 is firstly provided with its core and its pallets, the latter being for example riveted or fitted by force on the core;
• the coil carcass is then filled with wire, then its ends are connected to the terminals provided for this purpose; during this operation, the workpiece 70 is held on the winding machine is advantageously operated by the hooks 55, 57;
• the part 70 is then introduced laterally into the internal flow guide part 71 and on the G side or one of the longitudinal walls is missing; this introduction is facilitated for example by means of notches 72, 73 made on the internal branches, in the extension of the passage openings 72 ', 73' which are crossed by the core 43;
• the assembly of the part 70 and of the part 71 is then engaged, crosswise, see direction A in FIG. 6, towards the external branch 57 of the flow guide part 71 and provided with its magnets; this engagement can be facilitated by a lateral notch 75 of the branch 57 ensuring the extension 66 an easier passage, see FIG. 7;
• after the coaxial alignment of the two parts 74 and 71, the latter is pushed axially so that the hooks 55, 57 are coupled with the edges of the external branch 57;
• the part 62 is, if necessary, put in place.

The means for connecting the ends 78 of the wire of the coil 3, see FIG. 9, can advantageously be attached to two of the columns such as 79 belonging to the molded part 70 ′, in the form of solder lugs, screw terminals, or rigid or flexible metal pads 80 capable of operating an electrical connection by pressure and / or sliding; Figure 9 shows the latter solution; if necessary, terminals can be placed at the ends of the hooks which do not come into contact with the external branch.

The lateral retention of the part 71 inside the part 74, which can be ensured by the cooperation of the columns and hooks with notches 54 and 81 belonging respectively to these two parts, can be supplemented by the contact of bosses of part 70 such as 82, 83, 84, 85 with the longitudinal partitions 86, 87 of part 74, see FIG. 8.

Claims (12)

1. A polarized electromagnet (1) comprising:

a coil (3) adapted to be supplied with DC current; a magnetizable core (5) which is movable between two longitudinal end positions (R, T) occupied alternately by sliding inside the carcase (2) of this coil (3) and which has two opposite widened pole portions (9, 10; 12, 13) extending transversely with respect to the axis (XX') of the coil (3);

a fixed yoke having axially on each side of each widenend pole portion (9, 10; 12, 13) a pair of pole extensions (20a, 20b; 16a, 16b; 18a, 18b; 21a, 21 b) having opposite magnetic polarities which are conferred thereon by permanent magnetic means (22, 23) placed therebetweeen and orientated so that their magnetic axes (NS, N'S') are parallel to said axis (XX'), said widened pole portions (9, 10; 12, 13) cooperating with said extensions (20a, 20b; 16a, 16b; 18a, 18b; 21 a, 21b) so that, for each of the two end positions (R, T), the magnetic flux sent by these magnetic means (22, 23) through the core (5) is of reverse direction, characterized in that two pairs of extensions (20a, 20b) (16a, 16b) of the same first first magnetic sign, placed symmetrically with respect to said axis (XX') of the coil (3) form part of a same first rectangular flux channelling piece (17) surrounding a second flux channelling piece (19) which connects together two other pairs of symmetrical extensions(18a, 18b; 21a, 21b) having signs opposite to the first one and which surround a coil (3) whose carcase (2) is substantially traversed by the magnetic axes (NS, N'S') of permanent magnets (22, 23) disposed at the same level between transverse flux channelling branches (18, 20).

2. The polarized electromagnet as claimed in claim 1, characterized in that said first flux channelling piece (17) and said second flux channelling piece (19) are in the form of two rectangular frames which are placed one in the other and have passing concentrically therethrough the core (5) and respectively an external extension (7) thereof.

3. The electromagnet as claimed in claim 1 or 2, characterized in that an extension (30) respectively (34) of the core (5) comprises a third transverse plate (31) respectively (33) which establishes with an external branch (20) respectively (16') of the external flux channelling piece (17) and for one of the positions of the core, a small reluctance so as to divert a fraction of the flux supplied by the permanent magnets (22, 23).

4. The electromagnet as claimed in claim 3, characterized in that said third plate (31) rests on the outside of the external branch (20) with which it cooperates for each of the two end positions (R, T) of the core.

5. The electromagnet as claimed in claim 3, characterized in that said third plate (33) is placed in the plane of the internal branch (21') with which it cooperates throught the presence of a calibrated opening (35) therein, and for one of the end positions (R, T) of the core.

6. The electromagnet as claimed in one of claims 2 to 5, characterized in that said two frames (17, 19) are placed in the same plane.

7. The electromagnet as claimed in one of claims 2to 5, characterized in that said two frames(17,19') are respectively placed in two planes which are perpendicular.

8. The electromagnet as claimed in one of claims 2 to 7, characterized in that one of said rectangular frames (19) respectively (71) is without one of its longitudinal dividing walls.

9. The electromagnet as claimed in one of claims 1 to 8, characterized in that a molded piece (70) comprising a flat portion (44, 60) perpendicular to said axis (XX') and columns (49, 50) parallel thereto having hooks (55, 57) applies two transverse branches (53, 57) of said flux channelling pieces (71, 74) against the pole faces of the magnets (58, 59) and establishes a coaxial alignment of these two pieces.

10. The electromagnet as claimed in one of claims 1 to 8, characterized in that a molded piece (62) which has lateral retaining means (63) for the magnets and which at the same time effects an angular orientation of the plates and of the core is fixed to one of said flux channelling pieces.

11. The electromagnet as claimed in one of claims 9 or 10, characterized in that said molded piece (70) also carries the carcase (40, 42, 44, 45) of the coil (3).

12. The electromagnet as claimed in one of claims 9 and 11, characterized in that two of the columns (79) of the molded piece (70') serve for maintaining in position connecting members (80) connected to the ends (78) fothe wire of the coil (3).

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