US2443398A - Electronic sequence timer - Google Patents

Description

June 15, 1948. J, J, N 2,443,398

ELECTRONIC SEQUENCE TIMER Filed Nov. 6, 1944 mmvron JOSEPH J. NEFF ATTORNEY Patented June 15, 1948 ELECTRONIC SEQUENCE TIMER Joseph J. Neil, South Euclid, Ohio, assignor, by

ignments, to Jack 8: Heintz Precision Industries, Inc., Cleveland, Ohio, a corporation of Delaware Application November 8, 1944, Serial No. 562,207

This invention relates to an electronic system for measuring a succession of timed intervals for performing a sequence of operations and the like.

The object 01 the invention, in general, isto provide an electronic timing system of greater simplicity and or greater ruggedness and reliability than conventional systems for this purpose.

A further object is to provide a timing system based upon condenser charging and discharging cycles wherein a single timing circuit may be utilized for timinga succession of intervals of either uniform or non-uniform duration, without duplication of the system for each interval to bemeasured. v A further object is to provide an electronic timing system embodying charge accumulating means, a plurality of discharge circuits for discharging the accumulating means at different rates, and switching means operable in step-bystep action in response to charging and dischargin cycles to efiect a repetition of said cycles with said different discharge circuits successively, and to successively energize a corresponding plurality of external circuits successively.

The invention will now be described with reference to the accompanying drawings in which:

Figure 1 is a wiring diagram 01' a preferred embodiment of such a system designed for, con trolling a sequence of tour successive timed intervals or operations and;

Figure 2 is a simplified wiring diagram show- 3 ing the basic elements of the timing circuit'as applied to a single timing interval.

Corresponding circuit elements in Figures 1 and 2 are designated by the same reference numerals, the description of a single timing cycle being readable upon both Figures 1 and 2.

In Figure 1 the numeral i designates an A. C. power supply for a transformer 2 having a line switch 3, a. pilot light 4 indicating when the systemisenergized. The secondary 5 provides a plate voltage for a thyratron type tube 8 connected in circuit with the motivating electromagnet 1 of a stepping switch, and timing condensers 8 and 8. The stepping switch is protial oi secondary will ignite the thyratron 4 con- to energize the electromagnet 1, moving contactors Hi and il ahead one step and drawing the switch arm 20 into engagement with contact 22 to establish a charging circuit for the condensers 8 and 8, substantially the entire voltage drop of the secondary ll occurring across the coil 01' electromagnet 1 when the thyratron is conductive. This voltage drop charges the condenser 8 through the resistor 28 and charges the condenser 8 through the resistors 28 and 24 in series so that as these condensers charge the voltage rise across condenser 8 will lag the voltage rise in condenser 8, the voltage across condenser 9 at any given instant being less than that across condenser 8. The resistor 25, connected to grid 28, is a current limiting resistor required by the tube 8.

The condensers I and 8 will continue to charge until the grid 28 attains a sufilcient negative potential to extinguish the tube 8,. which potential is relatively low in conventional thyratrons). Extinguishing oi the tube 8 opens the circuit from the secondary 5 and de-energizes the electromagnet I. De-energization of the electromagnet 1 causes the switch arm 20 to leave stationary contact 22 and move into engagement with contact 2| to establish a discharge circuit through one of the variable resistors 21 to 80. In Figure 1 the contactor I8 is shown resting upon the contact H connecting the resistor 21 in V series with a fixed resistor 8| to discharge the timing condensers. At the moment or completing the discharge circuit the potential of condenser 8 is higher than the potential or condenser I so that the latter will continue to charge from the former, resistor 24 constituting a discharge path from condenser 8 in parallel with discharge resistors '21 and 8!. The potential of condenser 9 will then rise as the potential of condenser 8 falls, until the two potentials are substantially the same, and thereafter both condensers will discharge in parallel through resistors 2i 'and 8|. During this latter stage of ,the discharge it will be seen that the condenser I must discharge through the additional resistor 24 with the result that the fall of potential across condenser 9 will lag behind the fall of potential across condenser 8.

It the secondary 8 produces, for example, a potential of 250 volts, the voltage across condenser 8 may reach a peak value oi volts and the potential across condenser 8 at the time the tube is extinguished will be relatively small, inasmuch as a small negative potential on the grid 26 is effective to extinguish the tube. After the tube is extin uished, and the potential of condenser 8 begins to fall, the potential of condenser 8 will rise for above the value required to extinguish the tube. The condensers 8 and 8 will then ultimately discharge to potentials low enough to impose an igniting potential on the grid 26. The condenser 32 serves as a filtering condenser around the electromagnet l to prevent vibration or chattering in the latter.

The re-ignition of the tube 6 will again energize the electromagnet I to repeat the previously described cycle, moving the switch arm 20 from the contact 2! to the contact 22 and moving the contactors l and i5 ahead one step; The two series of stationary contacts II to ll and IE to is are preferably disposed in circular arrangements so that contactors l0 and I! may rotate always in one direction, moving from the last position to the first so as to repeat the sequence indefinitely as long as the switch 3 is closed. The possible number of timing intervals is thus limited only by the number of contacts which may be arranged in a circle for engagement by the revolving contactors. I

A primary advantage of the present system is that the condensers 8 and 9 may be used for timing a plurality of successive intervals of different durations by merely adjusting the resistance values of the respective discharge resistors 2! to 30. In this way a rather wide range of time values may be obtained for successive intervals without duplication of the timing condensers or control tube.

A terminal strip 33 carries a plurality of terminals 34 to 31 connected to one side of the line and terminals 38 to 4| connected to the respective contacts It to is for a. sequential energization (by the contactor 15 to connect the line potential to successive circuits. Neon lamps 42 to l! are connected with the contacts It to it in the manner shown to indicate which circuit is energized, and these lamps are preferably associated on a control panel with the respective manual controls for the variable resistors 21 to 80.

The present system is of especial utility in timing intervals for life tests of various mechanisms which may be inter-related in their operations, or which may be entirely unrelated, certain as I desired time interval, this interval will be faith fully reproduced for an indefinite number of succeeding cycles. This enables the variable resistors 2'! to 80 to be accurately calibrated so that mechanisms operating for short intervals and others operating for longer intervals. Thus, while one mechanism is being operated the remainder are at rest, the sequence repeating automaticall as long as the switch I is closed.

The values of voltage or other circuit constants 1 mentioned in the foregoing description are cited merely by way of example and do not constitute V a limitation on the structure or mode of operation,

it being understood that any values of voltage, resistance or capacitance may be used in combination which will produce the described cycle of operation.

Whereas with a single timing condenser a charge of only approximately three volts could be accumulated before a conventional thyratron tube would be extinguished, resulting in a very short charging and discharging cycle, the action of the second condenser 8 is such as to enable the charge on the first condenser toreacha relatively high potential for timing purposes, thereby making available a relatively long discharging cycle. Moreover, the second condenser, by its delayed cycles of charging and dischargin still further extends the timing interval obtainable with a given capacitance and supply voltage. It is preferred to accomplish the charging cycle at a'relatively fast-rate, obtaining most of the measvariable discharge resistor is set to produce a the desiredtime intervals may be adjusted by dial indexing means on the control panel.

Figure 2 shows the elements of the system of Figure 1 necessary to produce a single timing interval, and is pertinent to the foregoing description of the timing cycle. In Figure 2 the only functions of the electromagnet I would be to operate the switch arm 20 and a contactor to make and break a single circuit to the device to be timed. Also, in Figure 2 the transformer 2 has been omitted, the system being connected directly on the line I.

I claim:

1. An electronic timing system comprising a stepping switch arranged in a thyratron circuit to advance one step each time the circuit is energized, a first condenser arranged for charging by a potential in said circuit, a second condenser in series with. a resistance in a circuit parallel with said firstcondenser, a switch operable by said stepping switch to complete said charging circuit, a control grid responsive to .the potentialof said second condenser to ignite and extinguish said thyratron, said switch being operable by de-energization of said stepping switch to connect said tion, a'thyratron intermittently'energizing said stepping switch, a first condenser arranged for charging by said thyratron circuit, a second condenser under the control of said first condenser for controlling the ignition and extinguishing of said thyratron in accordance with condenser potential, and a plurality of variable discharge circuits arranged for selection successively and in rotation by said stepping switch for the individual timing of the energization of the respective first named circuits,

8. An electronic timing system for controlling a plurality of external circuits in succession comprising means to accumulate an electrical charge,

a charging circuit, a plurality of discharge circuits for discharging said charge accumulating means at different rates, and switching means operable in step-by-step action in response to charging and discharging cycles to effect a repetition of said cycles with said diflerent discharge circuits successively and to energize said external circuits successively.

' JOSEPH J. m.

REFERENCES CITED The following references are of record in the

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