GB1584239A

GB1584239A - Electromagnetic release device

Info

Publication number: GB1584239A
Application number: GB4318/78A
Authority: GB
Original assignee: SATELE
Current assignee: SATELE
Priority date: 1977-02-09
Filing date: 1978-02-02
Publication date: 1981-02-11
Also published as: DE2804493A1; FR2380630A1; OA05982A; FR2380630B1

Description

(54) IMPROVEMENTS IN OR RELATING TO AN ELECTROMAGNETIC RELEASE DEVICE (71) We, COMPAGNIE GENERALE D'APPAREILLAGE ELECTRIQUE "C.G.A.E." S.A.T.E.L.E.M., a French body corporate of 32, rue Bréguet - 75011 PARIS, France, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to an electromagnetic release device, forming a component of for example a relay, circuit breaker or like current interrupting means, designed to meet more particularly two categories of new requirements, i.e. on the one hand, miniaturization of such devices, and on the other hand, the suitability of such miniaturized devices for their most currently contemplated use, namely, their mounting on printed-circuit cards as any other electronic components.

Accidents with catastrophic consequences have recently occurred in certain data processing centres and telephone exchanges using important digital processing installations. In such cases, whole cabinets full of printed-circuit cards plugged side by side into connectors arranged in rows are enclosed in a same room. The printedcircuit cards are usually arranged vertically in order to facilitate ventilation and the spacing between the cards in a same row is practically standardized to correspond to the maximum width of the largest electronic components used. A complete installation of this kind using several cabinets full of electronic components is obviously very expensive. On the other hand, the risks of failure of the installation are not inconsiderable in view of the number of components. It has happened that a fault in just one printed-circuit card resulting in a short circuit has started a fire which has destroyed the whole installation. Designers have therefore recognized the necessity for equipping each printedcircuit card with one or several individual circuit breakers designed to immediately cut out at least part of the card on occurrence of an abnormal current at the card, e.g., in the direct-current supply. The needed next type of circuit breaker was therefore a miniature circuit breaker with the following mutually conflicting characteristics: it it had to be miniaturized in the extreme in order to be of a size compatible with the mean size of the electronic components mounted on the printed-circuit cards of present-day digital processing systems, in in particular, it must have a mini- mum base area in order not to be too difficult to be mounted on the printedcircuit card, and its height must be greater than the usually adopted spacing between the cards arranged vertically within a common cabinet, its sensitivity must be increased so as to be compatible with the usual orders of magnitude of the supply currents for such printed-circuit cards, lastly and above all, the resetting knob must be arranged on the side of the circuit-breaker housing so that when the housing is adequately mounted on the card the said knob is readily accessible and does not prevent other components being mounted in immediate proximity to the circuit breaker.

Devices meeting such requirements in association with those of miniaturization proper (reduced number of members, accurate assembly, etc.) are practically unavailable on the market. The present invention is the result of extensive research with a view to making all such requirements compatible with one another.

Otherwise stated, the shape and arrangement of the components of the device according to the invention as well as its external appearance have been conceived essentially for its contemplated application.

However, the same basic structure may be quite easily reutilized to develop an electromagnetic relay with quite as interesting performances.

According to the invention there is provided an electromagnetic release device, characterized in that it comprises: - two substantially flat flux-conductive side-walls or cheeks spaced in substantially parallel relationship to one another, - a bar magnet forming a cross-tie between the said side walls, the direction of magnetization of the said bar magnet being perpendicular to the mutually confronting surfaces of the said side walls, - an energizing or release coil wound around a flux-conductive core forming between the said side walls a cross-tie parallel with the direction of magnetization of the said bar magnet, - an actuating rod carrying a transverse, magnetic-circuit closing plate, the said rod and the said plate being guided in translation in a common direction perpendicular to the said direction of magnetization, the said plate being movable into engagement with the respective coplanar edges of the said side walls, and - a return spring bearing against the assembly of the said actuating rod and said plate, in a direction tending to move the plate away from the said coplanar edges.

It is understood that in such a structure, where the movement of the movable part (actuating rod and transverse plate) takes place perpendicularly to the direction of magnetization of the bar magnet and to the axis of the coil, both a reduced base area facilitating the mounting on the printed-circuit card is obtained and the occupied space in height with respect to the plane of the card is minimized since the actuating rod (which, in the case of a circuit breaker, also serves as an actuating knob) moves in a parallel direction to the plane of the card.

The invention will be better understood and other objects, details and advantages of the latter will appear more clearly from the following explanatory description of a particular form of embodiment of a circuit breaker according to the invention, given solely by way of example and with reference to the accompanying drawings wherein: -- Figure 1 is an exploded view of a circuit-breaker device according to the invention; - Figure 2 is a sectional view, to a larger scale, of the same device upon the line II-II of Figure 1, showing all the components of the device mounted in their respective functional co-operating positions; and - Figure 3 shows the same device mounted on a printed-circuit card of a complex electronic system.

Shown in the drawings is a miniature electric-circuit breaker or electric current interrupting device comprising essentially two half-casings 11 and 12 forming the protective insulating housing of the device, two flat metal side-plates or cheeks 13 and 14 in spaced parallel relationship to one another, a bar magnet 15, an energizing or release coil 16 wound around a cylindrical flux-conductive core 17, an actuating rod 18 carrying a transverse metal plate 19 serving to close the magnetic circuit, and a helical return spring 20. The bar magnet 15 and the core 17, which are mutually parallel and equal in length, form cross-ties between the side plates 13 and 14, as can be seen in Figure 1. It should be noted, however, that a gap may be provided between the bar magnet and the side walls 13, 14. The direction of magnetization N-S of the bar magnet 15 is perpendicular to the mutually opposite surfaces of the side walls 13 and 14. The side walls are positioned and adhesively retained in lateral cavities 13a 14a provided in the half-casing 11, so that their edges 13b, 14b project outwardly of the said half-casing. Preferably, after adhesively securing the side walls in the half-casing 11, the edges 13b, 14b are planed, as by grinding, so as to render them rigorously coplanar. Such mounting and machining features are important since the edges 13b and 14b provide bearing surfaces for the movable transverse plate 19. The plate 19 is provided with a central hole 25 the diameter of which corresponds to that of the rod 18 so as to allow for relative sliding motion between the rod 18 and the plate 19. Furthermore, the rod 18 is provided with a transverse stop collar 26 displaying two opposite bearing faces 27 and 28 so that the plate 19 can bear against the face 27 whereas the return spring 20 coaxially surrounding the rod 18 bears against the opposite face 28. The transverse plate 19 is urged towards the bearing face 27 by an auxiliary helical spring 30, but this auxiliary spring is designed so that the force which it exerts on the plate 19 is markedly smaller than that of the return spring 20 applied to the face 28 of the stop 26. As the previously mentioned spring, the spring 30 is arranged coaxially around the rod 18 on the other side of the stop 26 with respect to the spring 20.

The actuating rod 18 and the transverse plate 19 are guided in translation within the housing in perpendicular relationship to the direction of magnetization N-S, this movement being stopped in one direction when the plate 19 moves into engagement with the ground coplanar surfaces 13b 14b.

The guiding of the rod 18 is ensured in the simplest manner by means of two mutually opposite apertures 31, 32 provided in the half-casings 11 and 12, respectively. Furthermore, the end 33 of the rod portion carrying the auxiliary spring 30 projects laterally outside the housing in at least the open or break position (shown in phantom lines in Figure 2) of the device. The end 33 thus forms the reset knob of the circuit breaker.

The two half-casings 11 and 12 also accommodate a break circuit 35 including of course the above-mentioned coil 16. This circuit comprises two plug-in pins or access terminals 36, 37 projecting from the base face 38 of the housing formed by the two half-casings 11 and 12 assembled together (Figure 2). It is therefore seen that in accordance with what has been said earlier, the base face 38 and the actuating rod 18 are located as far apart as possible, and the actuating rod 18 is adapted to move in a parallel direction to the said base face. The break circuit 35 comprises a first metallic connector 39 electrically connected by means of welding to the end 40 of the coil 16, a second metallic connector 41 parallel with the first connector and integrally formed with and thus electrically connected to the access terminal 36, and a flexible metallic contact blade 42, located between the two said connectors and secured by welding to the second connector 41 by its curved portion 43.

The flexible blade 42 carries a contact stud 44 forming with the first connector 39 the breaking means proper. The freely movable endmost portion 45 of the flexible blade 42 is placed on the path of movement of the transverse plate 19 (which path is indicated by the two endmost positions of plate 19 shown in Figure 2 in full lines and interrupted lines, respectively) so as to be pushed by the said plate towards the left in Figure 2, i.e.

towards the second armature 41, when the device is in its open or break position.

On the other hand, it should be noted that when the device is not open, i.e.

when the transverse plate 19 is applied to the coplanar edges 13 and 14b of the side walls 13 and 14, the contact blade 42 is disengaged from the transverse plate 19 and applied through its contact stud 44 to the first connector 39.

The other end 46 of the coil 16 is connected (welded) to a third metallic connector 47 resting on the bottom wall of the housing and electrically connected to (in fact prolonged by) the other access terminal 37.

A metal screen tube 48, e.g., of copper or brass, is interposed between the coil 16 and its core 17. When a current flows through the coil the said screen tube performs the function of a short-circuit turn through which a current induced by the coil passes. This results in retarding core induction. By these simple means the circuit breaker is prevented from being tripped by false alarms caused by transient current peaks of short duration, therefore involving no danger for the installation.

The operation of the device just described is quite simple and can be obviously inferred from the foregoing description. The rod 18 being depressed towards the right in Figure 2, the plate 19 is applied to the edges 13b and 14b of the side walls 13 and 14. The magnetic field of the bar magnet 15 therefore closes through the transverse plate 19 remaining applied with a certain force to the edges 13 and 14b. This application force is of course greater than the force exerted by the spring 20 on the stop 26. If, however, a current flows through the coil 16, the flux in the core 17 increases against the flux of the bar magnet 15. This aggregately results in a decrease in the force of attraction of the plate 19 against the side walls 13 and 14. When the current in the coil 16 reaches a definite threshold accurately predetermined by appropriately selecting the characteristics of the coil, the bar magnet 15 and the spring 20, the force of application of the transverse plate 19 becomes smaller than the force exerted by the spring 20, thus releasing the actuating rod 18 and displacing it towards the left in Figure 2. During this movement the rod 18 drives along the transverse plate 19 which in its turn repels the flexible contact blade 42 thus opening the break circuit 35 and interrupting the flow of current between the terminals 36 and 37 of the device. The end 33 of the rod 18 then noticeably protrudes from the housing of the device, thus showing that the device is in its open position. So, an operator entrusted with the supervision of the electronic system, a small section of which is shown in Figure 3, is able to immediately locate any fault that may occur, by checking the condition of the circuit breakers mounted on the various printed-circuit cards. After eliminating the fault and, if necessary, changing the faulty card, the new card may be cut in by simply pressing on the end 33 of the rod 18, thus reapplying the transverse plate 19 to the coplanar edges 13b and 14b of the side walls 13 and 14. The plate 19 then remains in that position until such time as a further abnormal current is detected. In this connection, an important advantage of the resetting system just described should be noted. It has indeed been found that the releasing threshold of a circuit breaker may vary according to the manner in which the operator resets the device subsequent to breaking, more particularly in accordance with the force with which he presses on the resetting knob. It will be observed that in the arrangement described it is not the operator's actuating force that reapplies the transverse plate 19 onto the edges 13b 14b (this force serving only to move the rod 18 against the action of the spring 20) but rather the combined return forces of the spring 30 and the flexible contact blade 42. Otherwise stated, the resetting pressure on the transverse plate 9 9 is always identical with itself and corresponds to a value selected by the manufacturer. It will also be observed that the auxiliary spring 30 is not indispensable.

for the return travel of the flexible contact blade 42 is often sufficient to move the transverse plate to a location very close to the edges 13 and 14b, where there is a sufficient magnetic field to cause the plate 19 to be magnetically attracted towards the cheeks 13, 14, thus completing its resetting travel.

It will be appreciated that the same basic system may be used with a relay instead of a circuit breaker, in which case the flexible blade 42 becomes useless and can be dispensed with. It is then sufficient to add a system of movable contacts whose actuation may be, for example, mechanically connected to the motion of the rod 18. Instead of a system of contacts there can also be provided any suitable mechanical system, in particular the operating member of a valve.

WHAT WE CLAIM IS: 1. An electromagnetic release device, characterized in that it comprises: two substantially plane, flux-conductive side-walls or cheeks spaced in substantially parallel relationship to one another, --a bar magnet forming a cross-tie between the said side walls, the direction of magnetization of the said bar magnet being perpendicular to the mutually opposite surfaces of the said side walls, ~~ an energizing or release coil wound around a flux-conductive core forming a cross-tie between the said side walls in parallel relationship to the direction of magnetization of the said bar magnet, ~~ an actuating rod carrying a trans- verse, magnetic-circuit closing plate, the said actuating rod and the said transverse plate being guided in translation along a same direction of displacement perpendicular to the said direction of magnetization, the said transverse plate being adapted, during the said displacement, to move into engagement with two coplanar edges pertaining to the said side walls, respectively, and a return spring bearing against the assembly constituted by the said actuating rod and the said transverse plate and acting thereon in a direction tending to move the said plate away from the said coplanar edges.

2. A device according to claim 1, characterized in that the said actuating rod is provided with a transverse stop collar displaying two mutually opposite bearing faces, that the said transverse plate is provided with a central hole in which the said rod slides, so that the said transverse plate can move into engagement and bear against one of the faces of the said transverse stop, and that the said return spring bears against the opposite face of the said transverse stop.

3. A device according to claim 2, characterized in that the said return spring is helical and arranged coaxially about the said rod.

4. A device according to one of claims 2 to 3, characterized in that it comprises an auxiliary spring bearing against the said transverse plate in a direction tending to apply the latter to the corresponding face of the said transverse stop, the said auxiliary spring exerting on the said transverse plate a substantially smaller force than that of the said return spring on the said transverse stop.

5. A device according to claim 4, characterized in that the said auxiliary spring is helical and arranged coaxially about the said rod.

6. A device according to one of the foregoing claims, characterized in that, the protective housing of the said device being constituted by two half-casings, both aforesaid side walls are secured, e.g., adhesively, within one of the half-casings with at least their respective aforesaid coplanar edges projecting outwardly of the said half-casing, the surfaces of the said edges being preferably planed to ensure a reliable contact with the said transverse plate.

7. A device according to one of the foregoing claims, intended more particularly to perform the function of a safety circuit-breaker, and comprising a break circuit including the aforesaid coil, characterized in that both access terminals or plug-in pins of the said circuit project from a base face of the housing of the said device, and that, in at least the open or break position of the said breaking circuit, at least one end of the said actuating rod also projects outwardly of the said housing at a location spaced a great distance from the said base face and in

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. releasing threshold of a circuit breaker may vary according to the manner in which the operator resets the device subsequent to breaking, more particularly in accordance with the force with which he presses on the resetting knob. It will be observed that in the arrangement described it is not the operator's actuating force that reapplies the transverse plate 19 onto the edges 13b 14b (this force serving only to move the rod 18 against the action of the spring 20) but rather the combined return forces of the spring 30 and the flexible contact blade 42. Otherwise stated, the resetting pressure on the transverse plate 9 9 is always identical with itself and corresponds to a value selected by the manufacturer. It will also be observed that the auxiliary spring 30 is not indispensable. for the return travel of the flexible contact blade 42 is often sufficient to move the transverse plate to a location very close to the edges 13 and 14b, where there is a sufficient magnetic field to cause the plate 19 to be magnetically attracted towards the cheeks 13, 14, thus completing its resetting travel. It will be appreciated that the same basic system may be used with a relay instead of a circuit breaker, in which case the flexible blade 42 becomes useless and can be dispensed with. It is then sufficient to add a system of movable contacts whose actuation may be, for example, mechanically connected to the motion of the rod 18. Instead of a system of contacts there can also be provided any suitable mechanical system, in particular the operating member of a valve. WHAT WE CLAIM IS:

1. An electromagnetic release device, characterized in that it comprises: two substantially plane, flux-conductive side-walls or cheeks spaced in substantially parallel relationship to one another, --a bar magnet forming a cross-tie between the said side walls, the direction of magnetization of the said bar magnet being perpendicular to the mutually opposite surfaces of the said side walls, ~~ an energizing or release coil wound around a flux-conductive core forming a cross-tie between the said side walls in parallel relationship to the direction of magnetization of the said bar magnet, ~~ an actuating rod carrying a trans- verse, magnetic-circuit closing plate, the said actuating rod and the said transverse plate being guided in translation along a same direction of displacement perpendicular to the said direction of magnetization, the said transverse plate being adapted, during the said displacement, to move into engagement with two coplanar edges pertaining to the said side walls, respectively, and a return spring bearing against the assembly constituted by the said actuating rod and the said transverse plate and acting thereon in a direction tending to move the said plate away from the said coplanar edges.

parallel relationship to the said base face.

8. A device according to claim 7, characterized in that the said breaking circuit comprises: a a first connector electrically connec- ted with one end of the said coil, a a second connector parallel with the first connector and electrically connected to one access terminal of the said circuit, and --a flexible contact blade located between the said first and second connectors and secured to the said second armature, a portion of which is placed on the path of movement of the said transverse plate so as to be repelled by the latter towards the said second connector.

9. A device according to claim 8, characterized in that, when the said transverse plate is applied to the said coplanar edges, the said contact blade is applied against the said first connector and thus engaged from the said transverse plate.

10. A device according to claim 8 or 9, characterized in that the other end of the coil is connected, as by welding, to a third connector which is itself electrically connected to, or integrally formed with, the other access terminal of the said circuit.

11. A device according to one of the foregoing claims, characterized in that a metal screen tube, e.g., of copper or brass, is interposed between the coil and its fluxconductive core.

12. A method of manufacturing an electromagnetic release device according to claim 6, of the type consisting in particular in introducing between two half-casings defining the protective housing of the said device, a magnet and a coil interposed between two substantially flat, fluxconductive side-walls or cheeks spaced in substantially parallel relationship to one another, characterized in that the said two side walls are secured, preferably adhesively, in one of the half-casings so that two edges of the said side walls, respectively, project from the said halfcasing, and that the said edges are planed, as by grinding, so as to make them coplanar.

13. An electromagnetic release device substantially as described herein with reference to and as shown in the accompanying drawings.

14. A method of manufacturing a device as claimed in claim 1 substantially as described herein with reference to and as shown in the accompanying drawings.