US656004A - Automatic resistance-reducing device. - Google Patents

Description

No. 656,004. Patented Aug.wl4, I900.

G. H. WHITTINGHAM. AUTOMATIC RESISTANCE REDUCING DEVICE.

(Application filed Dec. 4, 1897.)

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No. 656,004. Patented Aug. I4, 1900.

a. H. WHITTINGHAM.

AUTOMATIC RESISTANCE REDUCING DEVICE.

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STATES GEORGE H. WHITTINGHAM, OF BALTIMORE, MARYLAND.

AUTOMATEC RESISTANCE=REDUClNG DEVICE.

SPECIFIGATION forming part of Letters Patent N 0. 656,004, dated August 14, 1900.

Application filed December 4, 1897. Serial No. 660,743. (No model.)

To all whom it may con/00771.

Be it known that I, GEORGE E. WHITTING- HAM, a citizen of the United States, residing at Baltimore, in the State of Maryland, have invented certain new and useful Improvements in Automatic Resistance-Reducing Devices, of which the following is a specification.

This invention relates to an automatic start ing device for electric motors of that class wherein a resistance in the circuit of the motor is gradually reduced by cutting out the coils of resistance one after the other from that of the greatest resistance to that of the least resistance. Letters Patent of the United States No. 499,769, granted me June 20,1893, show a mechanism comprising a compound solenoid-magnet wherein a coarse-wire low resistance is used when starting the motor and a fine-wire high resistance while the motor is in operation. In my present invention a low-resistance heavy current is also first used and then a high-resistance small current;

yet the method of employing these currents by my present invention is radically different from that disclosed in my former patent. In the patent referred to there is a rigid connection between the movable resistance-controlling shoe and the armature of the solenoidmagnet. In my present invention the heavy current passes through the coil around the magnet only for the very brief period that is required to raise the weight whereby the power is stored which subsequentlyoperates the resistance-cutting-out device. This cutting-out device is then operated by such stored power without any further current passing through the coils of the magnet, which affords advantages that are obvious.

The invention is illustrated in the accompanying drawings, in which- Figure 1 is a diagrammatic View showing the circuits. Fig. 2 shows my invention of a weight interposed in the connection between the controlling-shoe and core of the magnet. Fig. 3 is a similar view showing a modification. Fig. 4: is a view separately of the armature or core of the solenoid used in the modification.

The letterA designates the solenoid-magnet wound with two coils, the coarse-wire lowresistance coil 1) and the fine-wire high-resistance coil 0. The armature or core (Z is movable in and out of the magnet, and on top of the magnet is an iron cap 0, which. serves as a magnet to retain the armature or core d when the latter has been drawn up. An arm or lever F is pivoted at one end f, and its free end carries a shoeg, which is moved over the insulated plates h of the rheostat placed in an arc of a circle. When the motor is at rest, the shoe g of the resistance-arm is in contact with a plate h, adjoining the first or highresistance plate h. A dash-pot governor J has its lower end pivoted at 7.1, so as to allow slight oscillatory movement to its upper end to accommodate the curved movement of the jointed connection. Z of the piston-rod m, which projects out of the upper end of the dash-pot.

The main-line wire is designated n n, and a switch 0 makes connection therefrom to the motor-circuit through wire p to the pivoted resistance-arm F, plate h, wire q,to the coarsewire coil 1) on the magnet, to wire 19 to the first plate h of the rheostat, to wire 19 to the motor Q, and then through wire 19 to the switch and to thermain line. The second or fine-wire coil 0 on the magnet is supplied with current by wire 1" branching from wire I), and then the small current passes from the coilc to wire r, to the field s, to wire p and back to the switch. This small current is always flowing through the circuit just described, r c r 319 and keeps the iron cap e and core d magnetized, and thereby the said armature or core is held in the up position, and the resistance-arm-F is also thereby held up, thus keeping the shoe 9 onthe rheostat at the point of least resistance while the motor is running.

The operation is asfollows: WVhen the current is first turned on by the switch 0, it flows to the two coils of the magnet by both circuits, the small current by the wirer and the heavy current by the arm F. The heavy current causes the armature or core at to move instantly upward, thereby storing the power hereinbefore referred to by, in the construction shown in Fig. 1, extending or stretching the spiral spring I, the tension of which spring constitutes the stored-up power. The dash-pot or governor J offers resistance to the quick movement of thegovernor-plunger 'm, and consequently the resistance-arm F at first is held back and makes but slow movement. Its first movement carries the shoe 1 from plate 7!. to the first plate h of the resistance-coil or rheostat, and thereby breaks the circuit of the heavy current from wire q to wire 1), and thus cuts out the coarse-wire coil 1), which also acts as a part of the starting resistance. The further movement of the shoe gradually cuts out the remaining resistance. It will be seen that the tension of the spring I will draw on the resistance-arm F, and thereby the shoe carried by the said arm will move over the plates from h to 7t and gradually cut out the resistance, and will then hold the arm F to the point of lowest resistance while the motor is running.

Fig. 2 shows a combination in which a weight I, a cord t and a pulley i connect the resistance-arm F and its shoe 1 with the armature (Z of the magnet and serve for storing power that will subsequently move the resistance-arm and shoe.

Figs. 3 and at show the same apparatus as in. Fig. 1, but also shows a modification in the arrangement of the two circuits which include the magnet. One feature of the modification consists in employing a special switch-arm to break the heavy-current circuit flowing'to the magnet, said switch-arm being moved by the armature or core. In this modification the armature or core d has a longitudinal slot 6, and a switch-arm it extends through the slot and has one end pivoted at u. The free end of the switch-arm contacts with a terminal *0 when the motor is not running and at the moment of starting. \Vhen the current is turned on to start the motor, the armature or core d is drawn instantly, and as it nears the limit of its traverse the switch-arm u will thereby be moved from the terminal e, and thus breaks the heavy-current circuit through the magnet. The operation of the other parts is the same as already described for Fig. 1.

The wirecircuits are as follows: The mainline wires are designated 02. a, and a doublepole switch 0' is employed. Three terminals w w 10 are in position to be put in circuit by the two arms of the double-pole switch when the current is turned onto the motorcircuit. A wire 19 connects from terminal to to the pivoted resistance-arm F. The heavycurrent circuit through the solenoid-magnet is by a branch wire 1" from the wire 23 to the special switch-arm u, then to the terminal 11, and by wire '0 to the coarse-wire coil 1) on the magnet, then to wire t and to terminal we at switch. The second or small'ourrent circuit is from switch-terminal 102 to wire 00, to the fine-wire coil 0 on the magnet, to wire 1T6, to wire r and to switch-terminal in. A branch wire 1 connects at the pivot 11 of the spiral arm and leads to the fields, then to wire 1) and to the switch-terminal w.

I do not herein claim the combination, with a rheostat arm or bar, of a spring or other resilient device for moving the same to cutout resistance, an electrical device for placing the spring under tension, and means for moving the rheostat arm or bar to cut in resistance.

Having thus described my invention, what I claim is 1. In an automatic resistance-reducing device, the combination of a resistance having contact-plates; a controlling-shoe movable over said contactplates; a magnet; a heavy current circuit including the magnet and resistance but operative through both only at the initial movement of the said controllingshoe; a small-current circuit direct from the main line and including only the magnet and field; and a spring or equivalent device to store power interposed in the connection betweenthe movable controlling-shoe and the armature or core of the magnet, whereby when starting, the heavy current passes through the magnet only for the brief period required to draw its armature or core and said current is thereby automatically broken, and the resistance is then gradually cut out by the action of the stored power.

2. The combination of a motor; starting resistance for said motor; a solenoid included in the resistance-circuit; a contact-shoe engaging the resistance plates; a spring or equivalent device to store power connecting the armature or core of the solenoid with the contact-shoe; and a governing device retarding the movement of the contact-shoe, whereby the momentary use of the starting-current will store sufficient power to accomplish the subsequent removal of the starting resistance from the motor.

3. In an automatic resist-ance-reducing device, the combination of a resistance having contact-plates; an arm pivoted at one end and at its free end carrying a controlling-shoe which moves over said plates; a solenoid included in the resistance circuit; a weight connecting the pivoted arm and the core of the solenoid; and a governing device connected with said pivoted arm.

In testimony whereof I affix my signature in the presence of two witnesses.

GEORGE H. NHITTINGIIAM. lVitnesses:

CHARLES E. MANN, J12, CI-IAPIN A. FERGUSON.

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