US2301928A - Control system for industrial vibrating machinery - Google Patents

Description

Nov. 17, 1942. H. E. BROWN I CONTROL SYSTEM FOR INDUSTRIAL VIBRATING MACHINERY Filed Sept. 21, 1940 INVENTOR. HUGH E. BROWN BY Patented Nov. 17, 1942 CONTROL SYSTEM FOR INDUSTRIAL VIBRATIN G MACHINERY Hugh E. Brown, Cleveland Heights, Ohio, assignor to The W. S. Tyler Company Application September 21, 1940, Serial No. 357,749

4 Claims.

This invention relates, as indicated, to a control system for industrial vibrating machinery.

A primary object of the invention is to provide a control system which will convert alternating current of a 60 cycle frequency into current of a lower frequency, as for example 15 cycles, which is desirable for use in vibrating screens and the like.

Another object of the invention is to provide a control system of the character described which is characterized by the absence of batteries and of parts which are subject to breakage or are likely to cause difficulty in their operation.

A further object of the invention is to provide a system which is extremely stable in use, and which will not produce appreciable variations in frequency, even where there are substantial flucuations in the voltage of the alternating current source.

A still further object of the invention is to provide a system, the frequency output of which is not appreciably affected by substantial variations in temperature and humidity.

To the accomplishment of the foregoing and related ends, said invention, then, consists of the means hereinafter fully pointed out in the claims; the annexed drawing and the following description setting forth in detail certain means for carrying out the invention, such disclosed means illustrating, however, but one of various ways in which the principle of the invention may be used.

In said annexed drawing:

Fig. 1 is a schematic diagram of an electrical circuit embodying the novel features of the invention, and

Fig. 2 is an oscillogram of the voltage waves supplied to the load in the circuit illustrated in Fig. 1.

Referring more particularly to the drawing, the circuit includes a source of alternating current of ordinary public utility voltage, as represented by the power lines I and 2. A load L is placed in one of these lines, the line 2 in this instance. Such load may be the magnet of a vibrating screen, or other load of an inductive character.

The circuit further includes three electronic tubes 3, 4 and 5. The tube 3 is a gaseous triode, such as a Thyratron or C-fi-J, having therein an indirectly heated cathode 6, a grid 1 and an anode or plate 8. The tube 4 is an audio-frequency oscillator, commonly known as a type #30 tube, and having therein a cathode 9, grid I and anode H. The tube 5 is a standard rechaving therein a cathode l2 and a pair of anodes l3 and I4.

Reference numeral l5 designates a power transformer, the primary coil l6 of which is connected to the supply lines I and 2, and which is provided with three secondary coils designated respectively by reference numerals l1, l8 and I9. This transformer supplies power to the various branches of the circuit.

The circuit further includes as essential parts an audio transformer 20, preferably one having a 5 to 1 ratio, a resistor 2| of 30,000 ohms, a resistor 22 of 5000 ohms, a resistor 23 of 4000 ohms, a condenser 24 of 4 micro-farad capacity, a condenser 25 of 4 micro-farad capacity, a condenser 26 of 2 micro-farad capacity, a condenser 21 of .5 micro-farad capacity, and a choke coil 28 of 30 henrys.

The circuit surrounding the tube 5 is what is known as a B eliminator, and is the standard circuit present in any A, C. operated radio of the present time.

The circuit involving the tube 4 is what is known as an audio-frequency oscillator, which jumps into oscillation and generates a pulsating effect which is controlled by the value of the condenser 26 and the adjustment of the rheostat or resistor 2|.

The foregoing circuit will produce 1800 impulses per minute, the nature and frequency of the impulses being indicated by the solid portions of the curve in Fig. 2 of the drawing.

The impulse from the audio oscillator is delivered to the grid 1 of tube 3, so that this tube will be placed in a condition to pass current 1800 times a minute, with the result that the vibrator L, which is connected through the plate and cathode circuit of the tube 3 will then respond to 1800 impulses per minute.

Of particular interest from the standpoint of novelty is the small oscillator involving the tube 4. The use of this oscillator obviates the use of batteries and involves no parts which are likely to break down or cause any difficulty in operation.

The circuit is very stable, and with voltage fluctuations of from 240 to 212 volts, the device did not jump out of its frequency. This stability under voltage fluctuations of a relatively wide range has not been found in any other circuits of which I am aware.

The circuit, moreover, is characterized by a frequency output which is not appreciably affected by substantial variations in temperature and tifier tube commonly known as a type #80 tube, humidity.

Other modes of applying the principle of my invention may be employed instead of the one explained, change being made as regards the means and stepsherein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I therefore particularly point out and distinct ly claim as my invention:

1. A control system for a reciprocating load comprising a load circuit, a source of alternating current potential, means for periodically energizing said load circuit from said alternating current source at a frequency below that of said source including an electric valve having control and plate electrodes and a hot cathode, circuit means connecting said load circuit in series with the plate-cathode circuit of said valve across said source, an audio-frequency oscillator including a thermionic valve having a control electrode and having an output circuit including a plate electrode inductively coupled to the control element of said electric valve, means for capacitatively coupling the control electrode and plate electrode of said thermionic valve; a rectifier connected to said alternating current source, means for energizing said oscillator from said rectifier, and variable control means connected between the rectifier and oscillator to vary the frequency of the oscillator.

2. A control system for a reciprocating load comprising a load circuit, a source of alternating current potential, means for periodically energizing said load circuit from said alternating current source at a frequency below that of said current source including a' thermionic valve having a control electrode and having output electrodes connected in series with said load circuit across said source, an audio frequency oscillator including a thermionic valve having cathode and plate electrodes and having a control element connected to the control element of said thermionic valve, a full wave thermionic rectifier energized from said source and connected to energize said oscillator, said connection including a transformer having a winding connected between the plate electrode of said thermionic oscillator and the plate circuit of said rectifier, and a second winding connected between the control electrode of said oscillator and the cathode thereof, and means for varying the period of oscillation of said oscillator.

3. A control system for a reciprocating load comprising a load circuit, a source of alternating current potential, means for periodically energizing said load circuit from said alternating current source at a frequency below that of said source including a thermionic valve having a control electrode and having output electrodes connected in series with said load circuit across said source, an audio frequency oscillator including a second thermionic valve having a cathode, a control electrode and a plate electrode, means for energizing the cathodes of said valves from said alternating current source, means connecting the control elements of said thermionic valves with their respective cathodes, said connection including a resistance and capacity in series, a thermionic rectifier energized from said source and connected to deliver rectified current to said oscillator, said connection including a filter network, and means for varying the period of oscillation of said oscillator.

4. A control system for a reciprocating load comprising a load circuit, a source of alternating current potential, means for periodically energizing said load circuit from said alternating current source at a frequency below that of said source including a thermionic valve having plate and control electrodes and having a hot cathode, means connecting the plate-cathode circuit thereof in series with the load circuit across said source, an audio frequency oscillator including a second thermionic tube having plate and control electrodes and a cathode, means connecting said control and cathode electrodes in parallel, respectively, with the control and cathode electrodes of said first-mentioned thermionic valve, said parallel connections being shunted by a series-connected resistance and capacity, a full wave thermionic rectifier connected to energize said oscillator, said connection including a filter network, a transformer, and means interposed between the filter network and said transformer for varying the period of oscillation of said oscil lator, and transformer means for energizing the cathodes of the respective thermionic valve, oscillator and rectifier from said alternating current source.

HUGH E. BROWN.

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