US1365421A - Control apparatus - Google Patents

Description

T. C. MAcKAY.

CONTROL APPARATUS. APPLICATION FILED JUNE'Q. 1919.

1,365,421, Patented Jan. 11, 1921.

WITNESSES: INVENTOR f W Thgas CMGC/Y Qy ATTORNEY UNITED STATES PATENT OFFICE.

THOMAS C. MAcKAY, 0F PITTSBURGH, PENNSYLVAN'IA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENN- SYLVANIA.

CONTROL APPARATUS.

Application filed June 9,

and it has special relation to liquid rheostats for governing the operation of induction motors or other translating devices.

One object of my invention is to provide a liquid rheostat, the effective specific or unit-volume resistance of which may be varied by pneumatic means in the form of a perforated member that is adapted to blow bubbles of air or other'suitable fluid upwardly through the rheostat.

Viewed from another angle, the object of my invention is to effect a sweeping of gas bubbles upwardly past the electrodes of a liquid rheostat to remove impurities in the solution and to carry away such injurious gases as may form at the surface of the liquid. 1

A further object of my invention is to provide an apparatus of the character in question wherein 'the rate of formation of bubbles is rendered responsive to the current or the voltage of the'induction motor or other translating device to be governed by the rheostat, whereby the volume and number of escaping bubbles corresponds to the isolation of differently sized bodies of electrolyte, and the total resistance of the rheostat is automatically varied to maintain a substantially constant current or voltage for the translating device.

My invention may best be understood by reference to the accompanying drawings, wherein- Figure 1 is a diagrammatic view of a complete control apparatus and system constructed and organized in accordance with the present invention; and

Fig. 2 and Fig. 3 are detail views, respectively in longitudinal and in transverse section, of a liquid'rheostat similar to that shown in plan view in Fig. 1.

Referringto the drawing, the system here shown comprises an induction motor 1 having a primary stator winding 5 and a wound rotor 6 that-is connected to a liquid rheostat .2, the operation of which is gov- Specification of Letters Patent.

Patented Jan. 11, 1921.

1919. Serial No. 302,710.

erned by means of a gas-venting apparatus 3 which is supplied from a suitable tank or reservoir 4 under conditions to be hereinafter more fully set forth.

The liquid rheostat 2 may, in general, be of any well-known construction and comprises a tank or incasing member 7 which contains a body of suitable-electrolyte S for immersing a plurality of electrodes or plates 9 corresponding to the three phases of the wound rotor 6 of t-he'induction motor 1. As is customary practice, four electrodes are provided, the two intermediate electrodes being connected, through conductors l0 and 11, to two of the collector rings of the rotor 6, while the two outer plates are connected together and communicate with the remain ing collector ring of the rotor 6 through a conductor 12.

Near the bottom of the rheostat 2, my gasventing device 3 is located and comprises a supply pipe or manifold 13 with which communicates a plurality of perpendicularly related pipes or tubes 15, 16 and 17, all of which are suitably perforated, as indicatedby the small circles. The respective pipes 15, 16 and 17 are preferably located in the spaces between the adjacent pairs of electrodes 9. A suitable piping arrangement 18 serves to effect communication between the manifold 13 and the supply tank 4 of air pressure or other suitable fluid, a valve 19 being interposed between the supply reservoir and the gas-venting device 3.

The valve 19 may be of any suitable type and is shown as provided with a movable plug 20, to which a magnetizable core member 21 is secured, around which an actuating coil 22 is wound. The coil 22 is shown as connected in series relation with the conductor 12, whereby the valve plug 20 is actuated upwardly or allowed to drop in accordance with the current that traverses the corresponding phase of the wound rotor 6. However, it will be understood that, if desired, the coil 22 may be energized in accordance with any other desired electrical condition, such as the primary or secondary voltage of the induction motor 1 or other translating device.

Neglecting for the moment the operation of the valve 19, it will be noted thatthe supply of air or other fluid under pressure to the perforated tubes 15, 16 and 17 forces bubbles or globules of such vfluid. to sweep upwardly through the spaces between the electrodes 9. Such action corresponds to the isolation of differently proportioned bodies of electrolyte, and the total resistance provided by the rheostat 2 is accordingly increased.

Not only is the specific or unit volume resistance of the electrolyte between the plates thus varied, but, in addition, the following advantages obtained by the use of my control apparatus. The rate of evaporation of the liquid and, consequently, the rate of removal of heat from the solution, is materially increased to prevent boiling and other similar undesirable effects of the assage of current through the rheostat. urthermore, small bubbles of hydrogen or other gases that ordinarily cling to the surfaces of the electrodes, and which chemically attack the electrode material, are removed by the sweeping action of the upwardly-flowing air bubbles, whereby the life of the electrodes is materially prolonged. Moreover, impurities in the solution itself are removed by flotation and bubbling, over of scum at the surface of the liquid through openings which may be provided in the sides of the containing vessel 7. In addition, if a continuous circulation of electrolyte is provided in accordance with any wellknown method, the present apparatus provides improved convection of heat, whereby a smaller and less expensive cooling apparatus, such as the familiar cooling coils, is permissible to provide a given degree of temperature reduction. Also, any explosive gases or vapors injurious to health that may form at the surface of the liquid in the rheostat are automatically carried away by means of the escaping air bubbles.

Referring to the automatic control of the rate of bubbling by means of the valve 19, it will be understood that, whenever the current in the rotor winding 6 increases, the core 21 is attracted upwardly by the coil 22 to enlarge the air passage through the valve 19 and thus force a greater volume of gas through the perforations in the several tubes 15, 16 and 17. Such increased rate of bubbling breaks up the electrolyte into smaller isolated bodies and thereby increases the resistance of the rheostat. Consequently, the current traversing the rotor winding 6 is again reduced to normal, and the valve 19 is again allowed to drop to an average position. The converse action occurs in the event of a decrease of the rotor current from the average value. In this way, the valve 19 is automatically actuated in accordance with the current traversing the rotor winding 6 to vary the resistance of the electrolyte in such manner as to maintain a substantially constant current in the rotor.

I do not wish to be restricted to the specific circuit connections, arrangement of parts or structural details herein set forth, as various modifications thereof may be made without departing from the spirit and scope of my invention. I desire, therefore, that only such limitations shall be imposed as are indicated in the appended claims.

I claim as my invention 1. In a liquid rheostat, the combination with a plurality of electrodes, of pneumatic means for varying the specific resistance of the liquid between said electrodes.

2. In a liquid rheostat, the combination with a plurality of electrodes, of means for blowing a fluid through the liquid between said electrodes to vary the resistance of the rheostat.

3. In a liquid rheostat, the combination with a plurality of electrodes, of means for blowing bubbles of gas through the liquid between said electrodes to vary the resistance of the rheostat.

4. In a liquid rheostat, the combination with a plurality of electrodes, of means comprising a perforated member for effecting the passage of gas bubbles through the liquid.

5. In a liquid rheostat, the combination with a plurality of electrodes, of a perforated hollow member located below the electrodes, and means for forcing a gas through the perforations.

6. In a liquid rheostat, the combination with a plurality of electrodes, of means for causing air bubbles to sweep upwardly past said electrodes.

7. In a liquid rheostat, the combination with a plurality of spaced electrodes, of a source of airpressure, and a plurality of perforated tubular members communicating with said source and located in positions to blow air upwardly through the spaces between the electrodes.

8. The combination with a translating device and a liquid rheostat for governing the operation thereof, of pneumatic means responsive to certain electrical conditions of said translating device for varying the specific resistance of the liquid in the rheostat.

9. The combination with a translating device and a liquid rheostat for governing the operation thereof, of means responsive to certain electrical conditions of said translating device for blowing a fluid through the liquid in the rheostat to vary the resistance thereof.

10. The combination with a translating device and a liquid rheostat for governing the operation thereof, of means responsive to certain electrical conditions of said translating device for blowing bubbles of gas through the liquid in the rheostat to vary the resistance thereof.

11. The combination with a translating device and a liquid rheostat for governing the operation thereof, of means comprising a perforated member for effecting the passage of gas bubbles through the liquid, and means responsive to certain electrical conditions of said translating device for regulating the rate of formation of such bubbles.

12. The combination with a translating device and a liquid rheostat for governing the operation thereof, of a perforated hollow member located near the bottom of the rheostat, means for forcing a gas through the perforations, and a valve responsive to certain electrical conditions of said translating device for regulating the rate of flow of such gas.

13. The combination with a translating device and a liquid rheostat for governing the operation thereof, said rheostat embodying a plurality of spaced electrodes, of a source of air-pressure, a plurality of perforated tubular members communicating with said source and located in positions to blow air upwardly through the spaces between said electrodes, and a valve responsive to certain electrical conditions of said trans lating device for varying the volume of air supplied to said perforated members.

In testimony whereof, I have hereunto subscribed my name this 31st day of May, 1919.

THOMAS C. MAOKAY.

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