US2333363A - Timing control system - Google Patents

Description

Nov. 2, 1943. c. J. COLLOM 2,333,363

\ TIMING CONTROL SYSTEM Filed Sept. 26, 1940 52 Q l 12w INVENTQR (7:25:15 1 6211017.

BY I

ATTOP a Patented Nov. 2, 1943 3 UNITED STATES PATENT. OFFICE TIMING CONTROL SYSTEM Cletus J. Collom, Detroit, Mich. Application September 26, 1940, Serial No. 358,473

(on. 2so=27 9 Claims.

The present invention relates to timing control systems, and in particular provides an improved timing control system in which all control functions are performed by valves of the electronic type, as distinguished from relays of the usual electromagnetic or other type.

It will be appreciated from a complete understanding of the present invention that, in a generic sense, the improvements thereof may be embodied in timing systems designed to produce widely varying sequences and designed for a wide variety of specific purposes. Ina more restricted sense, the present timing control system has been designed particularly to control an electric welding machine of theresistance type, so as to pro vide, without the use of electromagnetic control relays, a desired welding sequence.

The principal objects of the present invention are to provide a timing control system of the above indicated character, which is simple in arrangement and which is reliable in operation; to provide such a system comprising a plurality of related electronic valves, so arranged as to provide, without the use of cooperating electromagnetic or other translating devices, the hereinafter described operating'sequence; and to generally improve and simplify the construction and arrangement of electronic timing systems.

With the above, as well as other and more detailed objects in view, which appear inthe following description and in the appended claims, a preferred but illustrative embodiment of the invention is shown in the accompanying drawing, in which'the sole figure is a diagrammatic view of a circuit arrangement embodyingthe-invention.

Referring to the drawing,-the systemcomprises generally a series of electronic valves VI V2, V3, V4, V5, V6, V1, V8 and V9, all whereof are of usual construction, characterized asbeingv effective to transmit current in one direction so long as a predetermined potential of proper polarity is applied between the principal electrodes thereof, and so long as the potentials of the grids thereof are at or above a predetermined potential with respect to the associatedcathodes. As will be understood, however, when the grid potentials fall below the just-mentioned critical value, or stated-in another way, when a so-called blocking potential is appliedto the grids, the corresponding valves immediately become non-conducting.

Valves VI, V2, V4, V6, V1 and V9-areillustrated as being of the four-elementtype, each such valve being provided with a filament, a cathode, a grid and-a plate. The just-mentioned elements associated with valve VI are designated, respectively, f, c, g and p, and it will be understood that the corresponding elements for theother four element valves are correspondingly arranged. Valve V is provided with the above elements, and, in additiomis. provided with an auxiliary or" screen grid. The remaining'two valve v3 and vs are of the three-el ment tYbdcompnsrng 9- caithbli, a grid and a plate, whichelerhnts, for'valve V3, are designated, respectively, 0'3, 03 and p3.

Th details or tfi connections between the variousvalves may best be understood from a descriptiono'f vthe operation of the system as a Whole". Before proce ding to such a detailed desc rilitioli, hOWVeI, fili following summary Of the operation is given.

The startingof the system is under the contrOl of a pilot Switch o'f starfiil'ig device 1?, which i ma be of any suitable manual or' automatic ype, but'is' shown b'in'g' amanuan operable push button. closure" or the push button P initiates a s quence of operations, which causes t e valve v3 to conduct current and, energize the winding: or an electromagnetic val e mi The valve I'll is conventionally" arranged (by means nots'ho'wn') so that upon energizatiori it applies an or" other fluid pressure between the welding electrodes l2 and [4, .so as to move them into clamping" engagement with the'work in readiness for a welding peration; closure or thejp'ilot switch Palso initiates a further sequence-or operation's, which at the expiration of a predeter mined tl'm'e aftertlie e'iiergization of the electro magnetic valve" ll), causes the valve V8" to' conduct current. Thelatteractioii' causes welding current to besli'ppli'd to the e lctrode s', thereby initiating the weldirigactidii. ass-hows; valve vs directly energizes" a usual weldihlzijc'ont'a'ctor WC, the contact member a, whereof isfdirectlyjconnecteli in the primary circuit of the welding transformer T. 1

contemporaneously with the e'ner'gization of the welding circuit, timing means are actuated which" become" efie nve, at ul'e expiration" of" a; predetermined pence; tojinterrupt the flow of welding current. Thereafter; at the expiration 1 of what-isconventioiially'lrriown as a hold-time", the previouslymentioned electromagnetic valve" I0 is I de-eh'erg'i'zed, thereby automatically'relievin'g" the pressure between the 'electrode'sf and terminating the cycle;

In the present arrangement; also; timing means are rendered effective as an incident to" the timingaction, to preveirit'ule initiation of a second welding cycle for' a predetermined" period" after the release" of theelectrodesalttheconclusion of the j just mentioned first cycle.

ccnsideringnow' the: details orthesystem; the syste'm may be; conditioned for" operation by closing" the usual disconnect switches SI and" S2, which action connects thesuppiy conductors LI and L2 to a suitable sourceof alternating c'urrent. This action immediately energizes thefprimar'y windings of transfc'jrr'x'z'er's' T3, T4, T8, Tl I and HT, whichwinding's ara'll directlycoririe'cte'd between the" line" conductors" LI and 132,

as will be obvious. The transformer HT serves to supply heating current to the filaments or cathodes of all of the valves VI through V9, which relation is indicated by the reference character X applied to all such filaments or cathodes and to the terminals of the secondary winding of the transformer HT. So long as the line con" ductors LI and L2 are energized, accordingly, the filaments or cathodes of the several valves remain heated in readiness for operation.

The energization of transformers T3, T1 and TII renders these transformers effective to apply alternating potentials between the principal electrodes of the associated valves V2, V6 and V9, which actions are, however, without immediate effect, since, as described below, the corresponding said valves are in a blocked or non-conducting condition. The energization of transformer T4 applies an alternating potential between the principal electrodes of the valve V4, which is now in a conducting condition, and thereupon passes current to energize the associated transformers T5 and T6, the primary windings whereof are directly connected in the plate circuit of valve V4. The secondary winding of transformer T5 is connected to the grids of valves V2 and V3, and upon being energized, transformer T5 applies blocking potentials to the grids of valves V2 and V3, which valves are consequently rendered nonconducting'for the time being. The energization of transformer T6 applies a corresponding blocking potential to the grid of valve V6, which also thereupon becomes non-conducting for the time being. Transformer T6 also charges a weldingdelay condenser C2, which is included in the grid circuit of the valve V6.

The energization of transformer T8, which resulted, as aforesaid, from the initial closure of the disconnect switches SI and S2, applies alternating potential between the principal electrodes of the valve V1, which thereupon conducts cur rent and energies the transformers T9 and TIS. It will be noticed that the, primary windings of transformers T9 and T I9 are directly connected in the plate circuit of the valve V1 and upon being energized, transformers T9 and TH! apply blocking potentials, respectively, to the grids of valves V8 and V9. Transformer TI 0 also charges the weld-time condenser C3.

Assuming now that it is desired to effect a welding operation, the pilot switch P may be closed. This action directly energizes the primary winding of the control transformer TI, the secondary winding whereof thereupon applies alternating potential across the principal electrodes of the valve VI. Under the conditions stated, as aforesaid, the valve V2, which is associated with the grid circuit of valve VI, is non-conducting, and the grid of valve VI'is, therefore, at a potential which enables valve VI to conduct cur rent. The energization of transformer TI, therefore, causes valve VI to pass current and energize the control transformer T2.

The secondary winding of transformer T2 is included in the grid circuit of valve V4, and upon being energized, serves to charge up the holdtime condenser CI, and to also apply a blocking potential to the grid of valve V4. The action of the hold-time condenser CI, and its related now-blocked discharge valve V5 are described below.

Upon the application of the just-mentioned blocking potential to the grid of valve V4, this valve is immediately rendered non-conducting, which action immediately de-energizes the previously mentioned control transformers T5 and T6.

The de-energization of transformer T5 removes the previously existing blocking potentials from the grids of valves V2 and V3, whereupon these valves assume a conducting condition. Upon being rendered conducting, valve V2 passes current, as influenced by the transformer T3, and serves to not only charge up the off-time condenser C4, but to also apply a blocking potential to the grid of the valve VI. The latter action renders the valve VI non-conducting, thereby de-energizing the transformer T2. This action is without effect upon the conductivity of the valve V4, however, since the hold-time condenser CI remains fully charged and will remain so until a discharge circuit is provided therefor through the valve V5, as hereinafter described.

The removal of the blocking potential from the grid of the valve V3 renders the latter conducting. Consequently, valve V3 conducts current and energizes the winding of the electromagnetic valve it, which thereupon, as previously described, actuates the electrodes I2 and I4, so as to bring them into clamping engagement with the work.

The de-energization of transformer T6, which also resulted, as aforesaid, from the blocking of valve V4, enables the energy initially stored in the welding-delay condenser C2 to start discharging through the associated resistor R2. At the expiration of a predetermined period, accordingly, determined by the adjustment of the condenser C2, the grid of valve V6 assumes a conducting potential, thereby enabling the initially energized transformer T1 to cause a flow of current in the plate circuit of the valve V6. The time element provided by the condenser C2 is preferably sufiicient, as will be appreciated, to insure that the electromagnetic valve ID will have caused the electrodes to move into clamping engagement with the work before the flow of welding current is initiated.

The conductivity of the valve V55 enables the 1 transformer TI to apply a blocking potential to the grid of the valve VI, which, as will be recalled, was in a conducting condition at the beginning of the operations now being described. As a consequence of the just-mentioned action. valve V'I immediately becomes non-conducting, which action de-energizes the transformers T3 and'TID.

The secondary winding of transformer T9 is directly connected in series with the now deenergized transformer TI2 and with the grid of the valve V8, and upon the de-energization of transformer T9, valve V8 is rendered conducting. Consequently, a circuit is now completed, including the principal electrodes of valve V8, for the winding of the Welding contactor WC, which thereupon closes its indicated contact members to complete the circuit for the welding transformer T. This action, as will be appreciated, initiates the flow of welding current between the welding electrodes.

The secondary winding of transformer TIIl is directly connected to the grid of the valve V9, and upon the de-energization of transformer Till, the energy previously stored thereby in the weld-time condenser C3 starts to discharge through the associated resistor R3! At the expiration of ,a period determined by the charac teristics of condenser C3, the grid of valve V9 assumes a potential at which valve V9 is conducting, enabling the initially energized transformer Tl l to pass current between the principal electrodes of valve V9.

The flow of current through the valve V9 energizes transformers TI: and TH, the secondary windings whereof are included in parallel relation in the grid circuits of valves V8 and V5.

The energization of transformer T12 again applies a blocking potential to the grid of the valve V8, thereby interrupting the flow of current to the welding ccntactor WC. Consequently, the welding contactor WC resumes the illustrated open position, interrupting the flow of current through welding transformer T, and terminating the flow of welding current.

As aforesaid, the valve V is provided with an auxiliary or screen grid, which functions to retain valve V5 in a non-conducting condition, except when transformer Tlfl is energized. The energization of transformer T03, however, which results from the timing out of condenser C3, as aforesaid, immediately applies a potential to the other grid of valve V5, which overcomes the bias of the screen grid, andrenders valve V5 conducting.

As aforesaid, the plate circuit of valve V5 is connected in parallel with the hold-time condenser Cl. Upon being rendered conducting, acoordingly, valve V5 completes a discharge circuit for condenser Cl, through the resistor RF, and

at the expiration of a, predetermined period, sufficient to allow the work to cool sufficiently to cause the weld to set, the grid of valve V4 assumes a conducting potential. At this time, valve V4 again becomes conducting, re-energizing trans formers T5 and T5. The re-energization of transformer T6 again applies a. conducting potential to the grid of valve V6 in preparation for the next operation, as described below.

The re-energization of transformer T5 again applies blocking potential to the grids of valves V2 and V3. The latter action interrupts the flow of current in the plate circuit of valve V3, thereby de-energizing the electromagnetic valve f0 and relieving the pressure acting against the electrodes. The blocking of valv V2 interrupts the flow of current in the plate circuit thereof, thereby enabling the energy initially stored in the oiltime condenser C4 to start discharging through the associated resistor R4. At the expiration of a predetermined interval determined by the characteristics of condenser C4, the grid of valve VI assumes a conducting potential, in readiness for the next operation. It will be noticed that valve VI cannot be rendered conducting so as to initiate a succeeding cycle of operation until condenser Cl has timed out and this condenser, therefore, serves to determine the length of the period between the end of one complete welding cycle and the beginning of the next succeeding cycle.

The blocking of valve V5, which results, as aforesaid, from the re-energization of transformer T6, at the expiration of the hold-time period, again renders valve V'I conducting, which action, in turn, re-energizes transformers T9 and Till. The re-energization of transformer T9 is without immediate effect, since under the conditions stated, the grid of valve V8 is maintained at a blocking potential by the transformer TIZ.

The re-energization of transformer TI 0 applies a blocking potential to th grid of valv V9, which thereupon becomes non-conducting, deenergizing the transformers TH and I13, The de-energization of transformer Tl2 leaves the grid of valve V8 at a blocking potential under the influence of transformer T8. The de-energization of transformer Tl; renders the associated grid of valve V5 ineffective to overcome the biasing effect of the screen grid sg, associated with this valve, enabling the latter grid to maintain the valve V5 non-conducting.

It will be appreciated that the variou re-setting operations, which occur at the conclusion of the hold-time interval, determined by the timing out of condenser Cl, restore the system to the condition, described above, as existing immediately prior to the closure of the starting switch P.

If the starting switch P is in the closed position at the time condenser C4 times out, terminating the off-time interval and renderin valve VI conducting again, the consequent energized condition of transformer TI initiates a new welding' cycle, which duplicates in all respects the previously described cycle. If, on the otherhand, the switch P is in the open position at the time condenser C4 times out, such timing out does not initiate a new welding cycle for the reason that the transformer Ti is de-energized. A new welding cycle may, however, b initiated at any time after the timing out of condenser C4, by closing the switch P, a aforesaid. It will be recalled from the previous description that valve V'l remains conducting for only a very short interval at the beginning of such welding cycle. Consequently, the switch P is required to be held closed only during such momentary interval and thereafter may be opened without altering in any way the duration of the welding cycle, or altering in any way the duration of the off-time interval, which is provided by the condenser Cl.

It will be appreciated that by suitable adjustment of the various timing condensers and their associated timing circuits that the duration of the successive stages, described above, may be controlled between relatively wide limits, each such stage being adjustable over a range of from a few cycles of the alternating current source to a number of seconds.

From the foregoing, it will be appreciated that the present invention provides an extremely simple and efficient timing control system, and that various modifications in the form, number and arrangement of parts may be made Without departing from the spirit and scope of the invention.

What is claimed is:

1. In a, timing control system, the combination of an electric valve means having principal electrodes and a control electrode actuable to con-- trol the flow of current between said principal electrodes, an auxiliary valve associated with said control electrode, means normally rendering said auxiliary valve effective to apply a blocking potential to said control electrode, and timing means operable to first render said auxiliary valve ineflective to apply said blocking potential and for thereafter applying a blocking potential to said control electrode independently of said auxiliary valve.

2. In a timing control system, the combination of an electric valve having principal electrodes and a. control electrode actuable to control current flow between said principal electrodes, a circuitv for said control electrode including first and second energizable means either whereof is effective when energized to apply a blocking potential to said control electrode, and timing means for maintaining both said energizable means de-energized for a predetermined period and for thereafter energizing one thereof.

3. In a timing control system, the combination or an electric valve having principal electrodes and a control electrode actuable to control current flow between said principal electrodes, a circuit for said control electrode including first and second energizable means either whereof is effective when energized to apply a blocking potential to said control electrode, means normally rendering one of said energizable means energized and the other de-energized, and timing means operable to first de-energize said one energizable means and thereafter energize the other energizable means whereby to cause said valve to conduct current for a predetermined interval.

4. In a timing control system, first and second electric valves each having principal electrodes and a control electrode, said first valve being normally conducting and having its principal electrodes coupled to the control electrode of said second valve in such relation that when said first valve is conducting it maintains said second valve in a non-conducting condition, a starting device actuable between circuit-closing and circuit-interrupting conditions, means responsive to actuation of said starting device from one said condition to the other for impressing a potential on the control electrode of said first valve which renders it non-conducting, means effective after said first valve is rendered non-conducting for passing current between the principal electrodes of said second valve, and means operated as a consequence of said actuation of said starting device for removing said potential at the expiration of a controlled period.

5. In a timing control system, first and second electric valves each having principal electrodes anda. control electrode, said first valve being normally conducting and having its principal electrodes coupled to the control electrode of said second valve in such relation that when said first valve is conducting it maintains said second valve in a non-conducting condition, a starting device actuable between circuit-closing and circuit-interrupting conditions, means responsive to actuation of said starting device from one said condition to the other for impressing a potential on the control electrode of said first valve which renders it non-conducting, means efiective after said first valve is rendered non-conducting for passing current between the principal electrodes 4 of said second valve, and timing rneansoperably responsive to said starting device for removing said potential from said control electrode of said first valve after the expiration of a predetermined time interval.

6. In a timing control system, first and second electric valves each having principal electrodes and a control electrode, said first valve being normally conducting and having its principal electrodes coupled to the control electrode of said second valve in such relation that when said first valve is conducting it maintains said second valve in a non-conducting condition, a starting device actuable between circuit-closing and circuit-interrupting conditions, means responsive to actuation of said starting device from one said condition to the other for impressing a potential on the control electrode of said first valve which renders it non-conducting, means effective after said first valve is rendered non-conducting for passing current between the principal electrodes of said second valve, timing means operably re.-

sponsive-to said starting device and effective after the expiration of a predetermined period of conduction of said second valve to impress a potential on the control electrode thereof which prevents further such conduction, and translating means disposed to be operated by the said current flowing through said second valve.

'7. In a timing control system, first and second electric valves each having principal electrodes and a control electrode, said first valve being normally conducting and having its principal electrodes coupled to the control electrode of said second valve in such relation that when said first valve is conducting it maintains said second valve in a non-conducting condition, a starting device actuable between circuit-closing and circuit-interrupting conditions, means responsive to actuation of said starting device from one of said conditions to the other for impressing a potential on the control electrode of said first valve which renders it non-conducting, means effective after said first valve is rendered non-conducting for passing current between the principal electrodes of said second valve, and timing means operably responsive to said starting device for removing said potential from said control electrode of said first value after the expiration of a predetermined time interval, said removal of said potential again rendering said first valve conductive and enabling it to prevent further conduction through said second valve.

8. In a timing control system, first and second electric valves, said first valve having principal electrodes and a control electrode, said first valve being normally conducting and having its principal electrodes coupled to said second valve in such relation that when said first valve is conducting it prevents flow of current through said second valve, a starting device actuable between circuitclosing and circuit-interrupting conditions, means responsive to actuation of said starting device from one said condition to the other for impressing a potential on'the control electrode of said first valve which renders it non-conductive, means eiiective after said first valve is rendered nom conductive for passing current through said second valve, and means operated as a consequence of said actuation of said starting device for removing said potential at the expiration of a controlled period.

9. In a timing control system, first and second electric valves, said first valve having principal electrodes and a control electrode, said first valve being normally conducting and having its principal electrodes coupled to said second valve in such relation that when said first valve is conducting it prevents flow of current through said second valve, a starting device actuable between circuit-closing and circuit-interrupting conditions, means responsive to actuation of said starting device from one of said conditions to the other for impressing a potential on the control electrode of said first valve which renders it nonconductive, means effective after said first valve is rendered non-conductive for passing current through said second valve, and timing means controlled in accordance with the condition of said first valve for removing the said potential irom said control electrode of said first valve after the expiration of a predetermined time interval.

CLETUS J. COLLOM.

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