US2392810A - Electrical circuit controlling device - Google Patents

Description

Jan. 15, 1946. c ps 2,392,810

ELECTRICAL CIRCUIT CONTROLLING DEVICE Filed Oct. 51, 1941 A )3 \4 Q lo 2' NSULATION INSULATION BYUM ATTORNEY Patented Jan. 15, 1946 2,392,810 (7 ELECTRICAL CIRCUIT CONTROLLING DEVICE Hugo F. Cypser, New York,-N. Y., asslg'nor to Signal Engineering & Manufacturing Company, New York, N. Y., a corporation of Massachusetts Application October 31, 1941, Serial No. 417.338

2 Claims.

.The present invention relates to electrical circuit controlling devices, or relays, of the dualarmature type that are adapted for selective operation of their armatures at different current levels. A relay of this general type is particularly useful for fire alarm and similar signal systems employing a so-called master controller having a single winding normally traversed by a supervisory current of low value to hold up an auxiliary armature, with subsequent increase of the current (as upon operation of a sending station) serving to pull in a main armature controlling the alarm signal circuits.

Briefly stated, the relay of the present invention differs from the previously known relays of the dual-armature type, in that the functioning of the auxiliary armature, in response to the flow of supervisor current, definitely improves the path for the now of magnetic fiux which subsequently causes pulling in of the main armature, as contrasted to the shunting of the flux. This characteristic enables the relay to reliably operate with a closely selective action, due to the relatively small difference between the current levels that cause individual operation of the two armatures.

The above and other advantageous features of the invention will hereinafter more fully appear from the following description, considered in connection with the accompanying drawing, in which Fig. 1 is a view in front elevation of a relay embodying the present invention.

Fig. 2 is a view in side elevation of the relay shown in Fig. 1, in open circuit condition.

Figs. 3 and 4 are views in side elevation showing selective operation of the relay armatures at difierent current levels.

Fig. 5 is a plan view of the relay shown in Fig. 3, with a portion of the auxiliary armature broken away.

Referring to the drawing, the relay consists of a U-shaped magnetic core I mounted on an insulating base 2, with one leg of the core I surrounded by an energizing winding 3. The other core leg carries a main armature I pivoted at 5, and the armature 4 carries contacts 6 extending upwardly in the direction of spaced contacts I mounted on the base 2. As an example of the manner in which the relay may 'be utilized, it may 'be assumed that the relatively movable contacts 6 and I are'inoluded in the main circuit, or circuits, under control, such as the signal operating circuit of a fire alarm system.

An auxiliary armature 8 is pivoted at 9 between lugs I0 provided at the upper end of the core I,

with a portion of the armature overhan ini In air gap II in that portion of the core which connects the legs. A weight I! at the end of that portion of the armature 8 extending beyond the core serves to bias the armature 8 in a position slightly out of parallelism with that portion of the core in which the gap II is disposed. The auxiliary armature 8 occupies the position of Fig. 2 when there is no current traversing the winding 3, and it is to be noted that the air gap at A between the overhanging portion of the armature 8 and the core is very slight, and considerably less than the air gap at B between the main armature 4 and the end of the core leg carrying the wind ing 3.

As a further example of the manner in which the relay may be utilized, the auxiliary armature 8 is shown as carrying a contact I3 insulated therefrom at It, with the contact I3 being separated from a stationary contact I5 with the relay in the deenergized condition of Fig. 2. Assuming that the relay is being employed in a supervised fire alarm, or other signal system, as indicated above, the passage of a current of low amperage through the winding 3 will cause the auxiliary armature to pull in and close the contacts I3 and I5. The amperage of this pull-in current is of a value equivalent to that of the usual feeble supervisory current customarily employed in a fire alarm system, so that the continued flow of this current serves to maintain the contacts I3 and It in engagement to hold the usual fault indicating means of the system in condition to operate upon separation of these contacts. However, this supervisory current traversing the winding 3 will not; pull in the main armature 4, largely due to the fact that when supervisory current is first applied, an open gap exists in the main magnetic circuit at II. This gap II being of less width than the core I, as shown in Fig. 5, does not prevent the auxiliary armature 8 from pulling in, it being noted that when the armature 8 has once pulled in, the gap II is entirely bridged by the magnetic material of the auxiliary armature. In other words, pulling in of the auxiliary armature in response to the flow of supervisory current automatically improves the magnetic circuit 01 the main armature 4, although not to such an extent as to cause this armature to pull in due to the flow of supervisory current through the winding 3.

When the current traversing the winding 3 is materially increased over the value of supervisory current, (as by shunting out resistance from the supervisory circuit upon actuation of a sending station), the main armature 4 will pull up and hold the main contacts 6 and 1 closed. Since the previous pulling in of the auxiliary armature 8 has bridged the core gap H, to improve the main magnetic circuit, the diflerence in current values for operating the two armatures can be made less than were a solid core to be used. That is to say, the presence of the unbridged core gap l I so increases the reluctance of the main magnetic circuit that there is no possibility of the main armature pulling up on supervisory current. This magnetic circuit, however, is so improved through bridging of the gap H by the auxiliary armature 8, that the main armature 4 will pull in at a current level considerably closer to supervisory current level, than would be possible were the two armatures to be mounted on a common pivot, with difierence in weight between the armatures solely determining their diiferential operation.

Upon a decrease in the current traversing the winding 3 below the value that caused pulling in of the main armature 4, this armature 4 is bound to drop out first, due to its greater mass and to the fact that contact arms 6 are slightly flexed in their closed position. Furthermore, the auxiliary armature 8 is closely held by its attraction to the flat surface of the upper end of the core along the entire portion of the armature that extends to the left of the pivot 9. Therefore, the magnetic circuit tends to initially break more readily where the free end of the main armature 4 engages the lower end of the core leg, and when once the main armature has dropped out to create the main air gap B, a relatively feeble current through the winding 3 will continue to hold in the auxiliary armature.

I claim:

1. A circuit controlling device comprising a U-shaped magnetic core, one leg of which carries a winding, an armature pivotally mounted at the end of the other core leg and a second armature pivotally mounted at the top of said core, adjacent a gap therein, with said second named arma ture overlying said core gap, whereby pulling in of said armature at one current level through said winding serves to bridge said core gap to establish a path of lower reluctance for the flow of flux around said gap to assist in pulling in of said first-named armature at a diiierent current level through said winding.

2. A circuit controlling device comprising a U-shaped magnetic core, one leg of which carries a winding, an armature pivotally mounted at the end of the other core leg and normally separated from the first named core leg by an air gap, anda second armature pivotally mounted at the top of said core and normallyseparated from said core by an air gap less than the first named gap, with said second named armature overlying a portion of said core providing a permanent air gap therein, with pulling in of the second named armature at one current level through said winding serving to bridge said core gap to establish a path of lower reluctance for the flow of flux across said core gap to cause the pulling in of said first named armature at a different current level through said winding.

HUG'O F. CYPSER.

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