US2433254A

US2433254A - Electrical timing system

Info

Publication number: US2433254A
Application number: US639683A
Authority: US
Inventors: Aiken William Ross
Original assignee: Individual
Current assignee: Individual
Priority date: 1946-01-07
Filing date: 1946-01-07
Publication date: 1947-12-23
Anticipated expiration: 1964-12-23

Description

Dec. 23, 1947. w. R. AIKEN 2,433,254

ELECTRICAL TIMING SYSTEM Filed Jan. 7, 1946 r 24 r 34 1 (Z2 32 27 E 1 20/"? 'F M 3; pze 1H I N V EN TOR. M1 1 MM Foss Awe/v Arroe/vixs Patented Dec. 23, 1947 UNITED STATES PATENT OFFIEE 2,433,254 ELECTRICAL TIMING SYSTEM William Ross Aiken, Berkeley, Calif.

Application January 7, 1946, Serial No. 639,683

The present invention relates to timing devices adapted to delay commencement of an initiated operation and to determine the duration thereof, such devices being employed in signalling apparatus, welding equipment, heating arrangements, and the like.

More particularly, the present invention relates to electrical timing circuits employing tubes of the kind which become conductive only when a critical minimum voltage is applied thereto, in combination with means for building up the required voltage over a predeterminable period of time.

It is the principal object of the present invention to provide a timing system adapted to delay operation of a device controlled thereby and capable of maintaining the controlled device in operating condition for a predetermined interval of time.

It is another object of the present invention to provide an electric timing system which is,

tion to so arrange an electric timing system of the type referred to that weak currents incident to the operation thereof are at no times con,-

ducted through relay contacts so that failure due to corrosion of contacts is impossible.

Other objects of the present invention will appear from a description of the accompanying drawing, wherein the single. figure shows a time delay system embodying my invention.

' The system of my invention utilizes a plurality of tubes each of which possesses two electrodes and is of the type filled with an inert gas such as neon; it is unable to conduct any appreciable current until a sufficient voltage is placed across its electrodes to ionize the gas, whereupon it will conduct current until the applied voltage decreases below a critical value required to keep the gas ionized.

According to my invention systems utilizing tubes of the type described may be arranged so as to be capable of controlling not only commencement, but also duration of an initiated 2 Claims. (Cl. -320) operation over accurately predetermined periods of time. Additionally, such systems may be made to predetermine the duration of intervals between a series of sequential operations at will. An arrangement of this type is illustrated by way of example in the figure, wherein 20 is a battery, 2| a master control switch, 22 a timing resistor, and 25 a condenser, all connected in series. Condenser 25 in turn is connected across a gasdischarge tube 23 of the type previously described, and a relay 24. Means are provided in the form of a normally open'relay-operated contact 28 shunted across condenser 25 to prevent inopportune recharging of said condenser 25 upon closing'of said contact ,28. Relay 24 is connectible across battery 20 through a reducing resistor 21, a normally open relay-operated contact 26, and a normally closed relay-operated contact 30.

Battery 20 is arranged'to charge a second condenser 35 through a second timing resistor 32. Condenser 35 is connected across a second gas discharge tube 33 and a second relay 34, which latter may be of a much simpler form than relay 24. Charging of condenser 35 upon closing of master control switch 2| is initially prevented by a normally closed relay-operated contact 38 shunted across condenser 35.

When master control switch 2| is closed, condenser 25 is charged from battery 20 through timing resistor 22 until the voltage stored up in condenser 25 is sufilcient to ionize tube 23 whereupon the discharge current of condenser 25 through tube 23 will operate relay 24 to close initially open contact 26, thus connecting relay 24 across battery 20 and establishing a desired working status for whatever apparatus may be controlled by relay 24, relay-operated control switches for such apparatus being indicated at '40 and 4! in the figure. According to my inven tion, actuation of relay 24 is arranged to also close initially open contact 28 which shunts condenser 25 so that the same is discharged and cannot be recharged as long as contact 28 remains closed. In addition, actuation of relay 24 is arranged to open initially closed contact 38 so that condenser 35 may now charge from battery 20 through timing resistor 32. As soon-as condenser 35-is charged to a voltage sufflcient to ionize tube 33, relay 34 disposed in the circuit of tube 33 is excited, in which condition it is arranged to open normally closed contact 30, thus interrupting the circuit supplying relay 24 with current from battery 20. As a result thereof, relay 24 returns to inoperative position, terminat acaacu ing whatever operation may be controlled by said relay. In addition, deenergization of relay 24 opens

contacts

25 and 28 and closes contact 28 establishing conditions under which condenser 25 may recharge while condenser 35 is discharged and is prevented from recharging. As a result thereof, relay 34 is deenergized and permits return of relay-operated contact to its normal closed position. Hence initial conditions are established throughout the system, permitting condenser 25 to recharge and introducing a new cycle of operation.

The time delay between initiation 01' an operation by closing of master control switch 2| and actual commencement of an operation as controlled by actuation of relay 24 may be predetermined by selecting proper values for timing resistor 22 and condenser 25, either or both of which may be made variable. The duration of operation of a device controlled by the system of my invention may be predetermined by selecting the proper values for timing resistor 22 and condenser 35 which may likewise be made variable to permit adjustment to suit particular requirements. The time interval between successive operations of a controlled mechanism is again determined by the values of resistor 22 and condenser 25. In view of the simple task to be performed by relay 34 in the system of my invention as against the diversified control operations of relay 24, it will be understood that a relay of the simplest and most inexpensive construction may be used as relay 24 so that the cost of a second relay in addition to the more complex main control relay 24 will be very small.

In a practical embodiment of my invention according to the figure I employed components having the following values:

Voltage of battery 20: 125 volts.

Capacity of condenser 28: 4 microfarads.

Capacity of condenser 38: 4 mierofarads.

Critical voltages of tubes 23 and 35: ionizing voltage, 105 volts; deionizing voltage, 85 volts.

Value of resistor 22: 15 megohms.

Value of resistor 32: 10 megohms.

Value of resistor 21: 15,000 ohms.

Relay 24: 5,500 ohms.

Relay :4: 5,500 ohms.

I claim:

1. An electric timing system including a first and second capacitor, normally disabled means for charging said second capacitor, a first gas discharge tube and a first relay in series and connected across said first capacitor, a second discharge tube and a second relay in series and connected across said second capacitor, a circuit including in series said first relay, a normally open contact, a normally closed contact, and a source of voltage, said first relay being adapted, upon excitation, to close said normally open contact and to render effective said normally disabled means for charging said second capacitor, and said second relay being adapted, upon excitation, to open said normally closed contact.

2. An electrical timing system having a source of voltage, first and second circuits, each including a condenser. and a gas discharge tube and a relay connected across said condenser; normally effective means for charging the condenser of said first circuit from said source of voltage, and normally inefiective means for charging the condenser of said second circuit from said source of voltage; and a third circuit including said source of voltage, the relay of said first circuit, 2. normally open contact and a normally closed contact, said first relay being adapted upon excitation thereof through discharge current from said first condenser to close said normally open contact and to render effective said normally disabled means for charging said second condenser, while disabling said normally effective means for charging said first condenser, and said second relay being adapted upon excitation thereof to open said normally closed contact.

WILLIAM ROSS AIKEN.

REFERENCES CITED UNITED STATES PATENTS Name Date Kelly May 16, 1933 Number 1,909,471