US1753076A - Switch-actuating mechanism - Google Patents

Description

ril 1, 1930.

G. H. WHITTINGH AM SWITCH ACTUATING MEIGI'IANISM' Original Filed Dec. 8, 1926 Patented Apr. 1, 1930 UNITED STATES PATENT OFFICE GEORGE E. WHITTING-HAM, OF BALTIMORE, MARYLAND, ASSIGNOR TO MONITOR CON- TROLLER COMPANY, OF BALTIMORE, MARYLAND, A CORPORATION OF MARYLAND SWITCH-ACTUATING MECHANISM Original application filed December 8, 1926, Serial No. 153,304.

Divided and this application filed February 9, 1929. Serial No. 338,717.

This application is a division of my copending application, Serial Number 153,80 filed December 8, 1926. The invention relates to switch operating mechanism adapted particularly for use on alternating current circuits in connection with switches having contactors of large size and capacity which are normally biased toward open position by gravity, or springs, and which require large magnets and a considerable amount of electrical energy to move them to their closed positions. In mechanism of this character, if the alternating current is left flowing through the coil of the magnet which moves the contactors to closedposition, for the purpose of keeping them closed, the coil heats and is apt to burn out, and also there is in volved an unnecessary waste of electrical energy. In order to avoid this and other objections to the use of a switch actuating magnet as a holding magnet, I provide a relatively long operating arm or lever, for actuating the switch contactors, and a small holding magnet having a pivoted armature which is connected by a slot and pin connection to the free end of said arm in such a way as to exert strong leverage on said arm to keep it in closed position after it has been moved to such position by the main magnet. When the parts reach their closed positions, the circuit through the main magnet is interrupted automatically as hereinafter described.

The invention, in so far as the interlocking arrangement of the operating arm and the armature of the holding magnet is concerned, is applicable to switches and circuit breakers which are closed by hand, aswell as to electro-magnetically operated switches.

In the accompanying drawing,

Fig. 1 is a side view of a switch operating mechanism adapted for remote control, and embodying electro-magnetic means for closing and interrupting the main switch magnet, the operating arm being shown in open position in full lines and in switch-closing position in dotted lines, and the circuits being shown diagrammatically;

Fig. 2 is a detail view, showing the mechanism of Fig. 1 in front elevation; and,

Fig. 3- is a side elevation of a mechanism in which a switch-operating arm is manually closable, and the armature of a holding magnet is'connected to said arm as in the previous figures.

Referringto Figs. 1 and 2 of the drawing, a represents a switch actuating arm which is secured to a rock shaft 1, upon which any desired number of switch arms or oontactors may be mounted, two of these contactors being indicated at 2. The arm a comprises two parallel metal strips 3, between which is secured an armature 4, which is arranged near the pivotal end of the arm and opposite a pole piece of the main electromagnet b. The arm a is relatively long and extends to a considerable distance beyond the magnet Z), and it has near its free end a roller 5, mounted upon a pin 6, which is fastened to the sides of the arm and extends through a guide loop 7, which latter is secured to the armature 8 of a holding magnet c. The arm a and armature 8 are each pivoted to swing toward the pivotal axis of the other, and the pole-piece 10 of the holding magnet is between the pivotal points of the arm and armature. The guide loop 7 on the armature of the holding magnet connects said armature with the arm a so that'when the latter is rocked from the position shown in full lines in Fig. 1, to the position shown in dotted lines, or vice versa, the armature 8 will also be rocked about its pivotal point. The normal position of the arm a is that shown in full lines, where it is held by its own weight and by the weight of the contactors mounted upon the shaft 1. When the magnet b is energized, this magnet, acting upon the armature 4, causes the arm a to swing from the full line position to the dotted line position, and in this movement the roller 5 moves along the guide loop 7 toward the pivoted end of. the armature 8, and the latter moves down into contact with the pole piece 10. In this position, it is to be noted that the roller on the free end of the arm a is near the pivotal point or fulcrum 9 of the armature 8, while the free end of the latter is over the pole piece 10, at some distance from said pivotal point. When the magnet c is energized, the armatureserves as a. lever to hold the arm a firmly in the tion of the magnet.

position shown in dotted lines, and a very small amount of current in the coil of the holding magnet will sufiice to hold the arm a in this switch closing position, even when the contactors mounted on the shaft 1 exert a strong pressure tending to rock the arm a about its axis and away from the holding magnet.

The circuits in Fig. 1 are the same as those described and claimed in my original appli cation above referred to. The circuit for the main magnet Z) extends from the supply wire 11 through conductor 12 to the coil 13 of said magnet, thence by conductor let to the stationary contact 15 of an electro-magnetic switch 8, thence through contactor 16 of said switch, armature l7 and the core 18 of a magnet d, and thence to supply wire 19 which is grounded at 20 on said core. From the supply Wire 11, a conductor 21 leads through a manually controlled switch 22 to the coil 23 of magnet 13, and from said coil a conductor 2& leads to one terminal of coil 25 of magnet d, the other terminal of which coil is connected to supply wire 19 at the ground 20.

The operation of the mechanism shown in Fig. 1 is as follows Normally, the parts are in the position shown in full lines. sure of the hand switch 22, the coils of the magnets c and (Z, which are in series, are energized. As the armature 8 is held at a considerable distance from the pole piece 10 of the holding magnet by the arm a, the position of the armature is not affected by the attrac- T he armature 17 of the relay magnet d, however, is attracted and closes the switch 8, thus completing the circuit through the coil of the main magnet b. When this occurs, the main magnet attracts the armature on the arm a and the latter rocks the shaft 1, closing the switch contactors 2 thereon, and it also moves the armature 8 into contact with the pole piece 10 of the holding magnet 0. As the armature 8 swings toward the pole piece 10, the reluctance of the mag,- netic circuit of the holding magnet is de creased and the reactance of the coil 23 is increased, cutting down the current which flows through said coil and the coil 25 of the relay magnet. hen the armature 8 is practical-ly in contact with the pole piece 10, the reactance of the coil 23 is so greatthat only a small quantity of current can flow through the circuit'in which it is included, which circuit also includes the coil of the'relay. magnet. This reduction in the current Volume fiow= ing through the latter coil weakens the magnet (Z and its armature 17 immediately falls away from the magnet and opens the switch 8, thus breaking the circuit through the main magnet 79. The holding magnet alone then holds the arm a in the switch closing position, with very little current flowing in the coil of said magnet, owing to the leverage exertedby the armature 8.u-pon the free end of thearm a.

Upon clo- To release the arm a and to permit it to move to normal position, the operator opens the hand switch 22, which breaks the circuit through the coil of the holding magnet and the arm a rocks with the shaft 1 to the switch opening position and at the same time swings the armature 8'away from the pole piece 10 of the holding magnet.

In Fig. 3 is shown a switch arm a, which is movable to closed position by a handle 26, this arm carrying a contact blade 27, for engaging a brush contact 28, and a carbon contact 29. This switch arm is normally held in open position by a spring 30. The free end of the arm is connected to the armature 8 of a holding magnet c in the same manner that the arm a and the armature 8 are connected in the previously described figures, and the pole 10 of the holding magnet is arranged intermediate the pivotal points 31 and 32 of thearm a and armature 8, respectively. The supply wire 33 leads to switch arm a, andwhen said arm is in closed position, the current flows through the switch to overload coil 34* and wire 35 to a motor or other load. A conductor 36 leads from conductor 35 through the coil of the holding magnetto overload switch 34 and thence to lead wire 37.

\Vhen the switch arm a is moved manually to closed posit-ion, the circuit through the coil of the holding magnet is completed and the armature 8 is swung into contact with the pole piece 10, which holds the armature, and the arm a is thereby held in the switch closing position, a negligible amount of current being required in the coil of the holding magnet for this purpose. When the circuitof the holding magnet is interrupted, as by the opening of the overload switch 34, said magnet will release the armature 8 and the spring 30 will then rock the arma and the armature 8 to the position shown in Fig. 2.

What I claim is:

1. A switch-operating mechanism comprising arelatively long operating lever, a holding magnet and an armature for the nagnet pivoted adjacent the free end of the lever and having a sliding connection with a part on the free end of the 1 lever whereby the rocking movements of the lever are imparted to the armature, said lever and armature each adapted to swing toward the pivotal axis of the other when said lever is moved to switch closing position, said part adapted to lie close to the fulcrum point of the armature when the lever is in switch-closing position. I

2. A switch-operating mechanism com-prising a relatively long operating lever, a hold ing magnet, and an armature for the magnet pivoted adjacent the 'free end of the lever and having a sliding connection with a part on send free end, said lever and armature each adapted to swing towardthe pivotal axis of the other whenzsaid lever; is'moved; to switch closing position, and said magnet having a pole-piece intermediate said axes adapted to be engaged by said armature When the lever is in said position.

5 3. A switch-operating mechanism comprising a relatively long switch-operating lever, a main magnet for moving said lever to switch-closing position, a holding magnet near the free end of said lever and an arma- 7 time pivoted adjacent the holding magnet and movable by the lever, said armature adapted to hold the lever in switch-closing position While the holding magnet is energized.

In testimony whereof I affix my signature.

GEORGE H. VHITTINGHAM.

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