US2937322A - Magnet systems of electromagnetic regulators, relays or the like - Google Patents

Description

May 17, 1960 L. R. NIXON 2,937,322 MAGNET SYSTEMS 0F ELECTROMAGNETIC REGULATORS, RELAYS OR THE LIKE Filed July 13. 1953 lira].

iwd m Pawn Q T MAGNET SYSTEMS OF ELECTROMAGNETIC REGULATORS, RELAYS OR THE LIKE Leslie Reginald Nixon, London, England, assignor to J. Stone & Company (Deptford) Limited, Deptford, London, England Application July 13, 1953, Serial No. 367,620 Claims priority, application Great Britain July 14, 1952 2' Claims. (Cl. 317-158) This invention concerns improvements relating to the magnet systems of electromagnetic regulators, relays or the like, for example voltage regulators of the carbonpile type.

According to the present invention, the magnet system of an electromagnetic regulator, relay or the like comprises grain-oriented magnetic material. More particularly the magnet core of such a regulator, relay or the like consists of grain-oriented iron or steel in strip form.

Grain-oriented iron or steel strip, which is produced by a combination of rolling and annealing, has the crystal lattice structures of the grains oriented substantially in the same direction. Provided that the fiux path of a magnet core made from this material is everywhere, or substantially everywhere, parallel to the direction of easiest magnetisation of the strip, i.e. to the direction of rolling, a very low hysteresis value and high saturation density are obtained. In an electromagnetic regulator, it is particularly important that the hysteresis should be as low as possible if accurate regulation is to be achieved. Further, a somewhat higher fiux density can, if desired, be worked to.

One manner of applying the invention to the magnet core of an automatic voltage regulator of the carbonpile type will now be described by way of example and with reference to the accompanying drawing, in which:

Figure 1 is a front elevation of the magnet core in an initial stage of its. production,

'Figure 2 a similar view of the core illustrating further stages in production,

Figure 3 a side elevation corresponding to Figure 2, and

Figure 4 a perspective view of one form of regulator incorporating a similar completed core.

Known grain-oriented strip of silicon iron (for example about 0.012 in. thick) is wound upon itself over a temporary former to produce a body 1 of substantially rectangular O-shape (Figure 1) which is flat on the inside of the long sides. The starting and finishing points are, for example, at 2 and 3. The turns are then clamped or otherwise secured from unravelling and the first former is replaced by a soft-iron former with the two lower corners relieved. Soft-iron corner clamp pieces 4 of the shape indicated by chain lines in Figure 2 are then applied to the outsides of the said corners. Each corner piece consists of a small rounded plate extending across the width of the core on the outside and is secured by countersunk mild-steel screws 5 engaging in holes tapped obliquely in the wound strip material. The relieved corners of the former permit the ends of the screws to project inside the core. The end and side faces of the corner pieces are next machined off to the shape indicated by full lines in Figure 2, that is so that the said faces are nearly flush with the sides of the core. Other faces of the corner pieces may also be machined at this stage, if desired. Next the whole core is annealed to obtain the best magnetic properties. The materials of the corner pieces 4 and screws 5 should accordingly be capable of 2,937,322 Patented May 17, 1960 ICC 2 withstanding the annealing temperatures employed. The annealed core is impregnated with varnish which assists in holding the turns of strip material together.

The core is then cut through at one end, for example with an elastic wheel, to leave the substantial U-form shown in Figure 2, the ends of the screws being thus also removed. The gap faces produced may be ground to size. If required, the gap produced may be slightly flared outwardly.

Purely by way of example, Figure 4 shows a similar finished core suitably incorporated in one form of electromagnetic regulator. Windings 6 are applied to the side limbs of the core 1 which are then secured by rods 7 and clamping bars 8 to a supporting frame or bracket 9. An armature 10 of soft iron, or a laminated armature itself made of grain-oriented strips, is hingedly or pivotally mounted on the frame 9. As shown, an armature 10 which enters the gap 11 in the inverted U-core from below is supported by a clapper 12 which is hingedly mounted by means of crossed hinge springs 13 in per se known manner. An arm 14 of the clapper may be arranged to act upon a carbon pile or piles against the resistance of a spring. In the machining operations, surplus material may be removed from the core to facilitate the arrangement of the windings 6 over the limbs of the core and to afford registering faces for assembly with the frame 9.

In a core such as has been described, the flux path is everywhere in the direction of rolling of the strip, so that advantage can be taken of the lowest hysteresis value and highest saturation density. The former allows of improved accuracy being achieved and the latter of increased work being obtained from a magnet system of given size.

An alternative construction would be possible employing a U core which would be, say, just half the rectangular 0 form described above. Instead of carrying the laminations round from the cut ends of the U, soft iron pole pieces could be attached to these ends. For instance, the pole pieces could be supported from each other in a non-magnetic frame to which the U magnet (after threading on the coils) would be clamped in such a way that the soft iron pieces would form extensions to the limbs of the U.

The invention may also be applied to the magnet systems of relays, particularly in cases where it is important to have a very low differential value of ampere turns between closing and opening. In addition to moving-iron magnet systems, the invention may be applied to dynamometer magnets having moving as well as fixed coils, as for instance on certain regulators. In such a case the moving element might be a coil in the gap or alternatively a moving armature on which the coil is wound.

The invention may be used in magnet systems excited directly with alternating current, a laminated armature being employed as well as a laminated magnet core. In this case, the low hysteresis losses would be an additional advantage. Excessive losses due to the clamping screws could be avoided by using only one screw per side or by using screws of insulating material. Alternatively the screws and clamping pieces could be arranged to form a shading ring. Such anapplication of the invention would enable the use of a rectifier to be avoided where alternating current has to be controlled.

I claim:

1. A magnet system of an electromagnetic regulator or relay comprising a core in the form of a closed annular winding composed of longitudinally grain-oriented layers of wound magnetic strip material and provided with a cut forming core limbs whose ends are separated by a substantial open gap, machined corner pieces of solid magnetic material attached to the said ends of th.

arranged to be-attracted. by the said core into the: said gap. upon excitation: of the said winding.

2. A magnet system according; to claim 1,v and com?- prising securing means; attaching the said corner pieces to the said core; which securing, means pass transversely through the layers; of strip material, of: which the; core is imam-32a References Cited in the file of this patent composed and. hold. the; said. layers. together adjacent to. 10 2,595,755

the gap.

UNITED STATES PATENTS Foster Sept. 26, 1944 Camilli Aug. 14, 1945 White et a1. Jan. 22, 1946 Olson r Jane 15 I952 Granfield Feb. 19, 1952 Bedford May 6,, 1952'

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