US1892017A

US1892017A - Timing device

Info

Publication number: US1892017A
Application number: US580092A
Authority: US
Inventors: Stansbury Carroll; Glendon C Brown
Original assignee: Cutler Hammer Inc
Current assignee: Cutler Hammer Inc
Priority date: 1931-12-10
Filing date: 1931-12-10
Publication date: 1932-12-27
Anticipated expiration: 1949-12-27

Description

Dec. 27, 1932. c. STANSBURY ET AL 1,892,017

TIMING DEVICE Filed Dec. 10, 1951 Patented Dec. 27, 1932 UNITED STATES PATENT "OFFICE CARROLL STANSBURY, OF WAUWATOSA, AND GLENDON O. BROWN, OF MILWAUKEE, WISCONSIN, ASSIGNORS TO CUTLER-JXAJHIMIER, INCL, OF MILWAUKEE, WISCONSIN,

A. CORPORATION OF DELAWARE TIMING nnvrcn Application filed December 10, 1931.

This invention relates to electric timing devices and is especially applicable to timers forelectric welders, though not limited thereto.

In the co-pending application of LeVan and Stansbury, Serial No. 417,969, filed January 2,1930, a system is described in which current is supplied to a translating device various uses it has, under certain operating conditions, the disadvantage that it permits the operator to interfere with the normal timing of the apparatus. The system referred to also requires a relatively large energy storage capacity which is greatly reduced by the present invention.

In the system of Fig. 2 of the aforementioned application, it will be noted that a controlling tube is conducting at all times except during a definite period after the opening of a pilotswitch until the time when the potentials of the control grid has reached asufliciently low value to again permit passage of current through said tube. If, therefore. the pilot switch is again closed before the tube has become conducting through the action of the grid, the closure of the pilot switch immediatelychanges the grid potential, to a value which thereby shortens the time during which the tube is non-conducting. Such action is especially disturbing if the pilot switch is used to control the current to a wclden-as the weld may then receive an insuflicient amount of energy to produce a sound joint.

It has also been found that during the negative half cycle of the charging period of the energy storage circuit the latter partially discharges thus requiring a relatively large capacity of the storage circuit to accomplish the desired results.

The improved system'which is illustrated in the accompanying drawing in connection with a welding machine is a modification of that illustrated in Fig. 201 the aforementioned application.

Serial No. 580,092.

The present. invention has for its object to increase the accuracy with which the grid controls the starting of passage of current through the electron tube.

Another object is to provide improved ap paratus for controlling the timing function. 7 Another object is to provide apparatus which will make it impossible for the operator to interfere with the normal functioning and to insure correct timing-irrespective of the actuation of the pilot switch which is under his control.

Another object is to provide apparatus which requires a minimum capacity for the energy storage circuit.

Another object-is to provide a system which I very sharply responds to the change of conditions in the energy storage circuit thereby insuring very accurate timing.

y In the drawing, Figure 1 is a diagrammatic view of the system embodying my invention, while 7 Fig. 2. shows the voltage relations of the system.

f Referring to Figure, 1, l is a welding trans former having a primary winding 2 and a secondary winding 3. The secondary winding 3 is connected'to the jaws 4 of the welding machine. Preferably adjacent to the welder is provided a normally closed push button switch 5. Lines L and L are the terminals of an alternating current supply. A magnet switch 6 has a winding 7 and-normally open cooperating contacts 8 and 9 which are connected in series with the winding2 across the supply lines L and L A relay 10 has a magnet winding 11, normally closed main contacts l2, normally open auxiliary contacts 13 and -normally closed auxiliary contacts 14.v

to line L. A condenser 19 has its one terminal 19" connected to the grid 18 while the other terminal 19 is connectedthrough the resistance 20 to line L, and through the

re sistances

21 and 22 to line L. An adjustable resistance 23 is connected between the grid 16 and the normally closed contacts 14, which in turn are connected to terminal 19 of the condenser. One contact of push button switch 5 is connected to the common terminal of

resistances

21 and 22, while the other contact of said push button switch is connected through the normally open contacts 13 to the condenser terminal 19".

The system operates in the following manner:

\Vhen it is desired to make a weld, the material to be welded is introduced between the jaws 4 and the latter are pressed together.

A currentnormally flows from line L through winding 11 of switch 10 through the tube 15 to line L during positive half cycles of the alternating current.

Prior to the welding operation, the grid 18 of tube 15 is of such otential as not to impede current flow during the positive half cycle of the alternating current for the following reasons: Due to the dro of voltage through the resistance 20 a positive potential with respect to the cathode 16 is impressed upon a condenser plate 19" whose instantaneous value is equal to the instantaneous drop through said resistance. This results in a. negative charge of the condenser plate 19' of a. corresponding value. superposed upon this negative potential, due to the charge on the condenser is, however, the alternating positive potential aforementioned due to the voltage drop through the resistance 20 so that the resulting potential of the grid 18 is not sufiiciently negative to prevent discharge of the tube at the same moment of the positive half cycle. As a result, the contacts 12 are open and no current can flow through coil 7 of relay 6 so that the primary winding 2 of the welding transformer does not receive any current from the line. If the operator then wishes to apply current to the weld he pushes push button switch 5 thereby opening a circuit from the junction point of

resistances

21 and 22 through push button switch 5, contacts 13 to condenser terminal 19" thus inserting resistance 21 in series with

resistances

22 and 20. The potential of the condenser terminal 19 is thus suddenly reduced. due to the change in voltage drop through the resistance 20, causing a corresponding drop of the potential of condenser terminal 19" to a negative value which is sutlicient to prevent restarting of discharge through the tube on the succeeding positive half cycles. The coil 11 thereby becoming de-energized causes closure of normally closed contacts 12 thereby energizing switch 6 and completing the current supply to the welding transformer 1 so that now the welding jaws receive current. Decnergization of switch 10 also opens contact 13 so that the aforedcscribed circuit around resistance 21 remains open even though the operator releases the button 5. The condenser 19 gradually discharges over acircuit from plate 19 through contacts 14. which are now closed due to the de-energization of switch 10, resistance 23 to condenser plate 19". After a certaiii lapse of time. the potential of condenser plate 19 and grid 18 connected therewith has a ain been reduced to a value which permits t 1e tube 15 to conduct current during the positive half cycle, whereupon the switch 10 is energized thereby interrupting the current through contacts 12 and this in turn interrupts the current supply to switch 6 which interrupts the current of the welding transformer. It will be apparent that irrespective of the operation of the push button switch 5 the time during which the tube 15 remains non-conducting after initial operation of said push button switch remains constant and therefore a constant amount of energy is supplied to the welder.

It has been found that by providing for opening of the condenser discharge circuit at the switch 14. the condenser plate 19" can be charged to the full potential of line L less the drop in resitance 22 arid thus the maximmn possible negative potential is attained by the plate 19" and the grid 18. If this discharge circuit were closed at all times the current flowing in resistance 23 would produce an additional drop in resistance 22 thereby reducing the potential available to charge the condenser. Furthermore, the partial discharge of the condenser through resistance 23 during the intermediate periods is ohviated. By opening this discharge circuit the condenser plate 19" is thus charged to the highest potential available. This permits a reduction of the size of the condenser which is necessary to obtain a given timing period. The assurance of raising the charge on the condenser always to the maximum value reduces the variation in timing due to imperfect rectification of the cathode-grid path. and this is of special importance for short period timing adjustment.

Referring now to Fig. 2, E, is the voltage impressed upon the main electrode of the tube during the positive half cycle, E is the grid voltage necessary to prevent the tube from conducting, E is the voltage of the condenser after it has been charged to its maximum.

negative value by the depression of the push button 5, while E is the grid voltage which is equal to the condenser voltage plus the alternating component of the voltage drop through the resistance 20 due to the current passing through the

resistances

20, 21 and 22. It will be noted that this superposed alternating voltage is in phase with the plate voltage E, and produces at the beginning of the positivc half 0 c'le a greater rate of change than the rate 0 change of the condenser volta e alone. This causes a relatively rapid c ange of the grid voltage at the beginning of that half cycle when the latter becomes more positive than the voltage E, thereby producin a very ositive controlling effect on the tu e. Furt ermore, the grid voltage during each positive cycle reaches a value, which approaches the critical voltage more closely than the condenser discharge voltage, so that the former is reached and the tube is rendered conductive when the rate of change of the condenser voltage is still relatively high. This results in a more accurate-timing than would be possible without the biasing voltage.

The time during which the welder is supplied with current may be adjusted by adjusting the discharge resistance 23 or the condenser 19.

. \Vhat we claim as new and desire to secure by Letters Patent is:

1. In combination, a power supply, a trans-.

lating device supplied thereby, an electron tube controlling the continuity of circuit thereof and having a control electrode, means to impress upon said electrode a otential rendering said tube conductive to e ect completion of the circuit of said translating device, energy storing and discharging means associated with said electrode and having a transient effect thereon to cause said tube to interrupt said circuit of said translating device and means associated with said trans- -lating device to complete a circuit to effect discharge of said storing means upon interruption of said last mentioned circuit.

2. In combination, a power supply, a translating device supplied thereby, an electron tube controlling the continuity of circuit thereof and having a control electrode, means to impress upon said electrode a potential rendering said tube conductive to effect completion of the circuit of said translating device, energy storing and discharging means associated with said electrode and having a transient effect thereon to cause said tube to interrupt said circuit of said translating device, means to commutate the connection of said energy storing means and means associated with said translating device to complete a circuit to effect discharge of said storing means upon interruption of said last mentioned circuit.

3. In combination, a power supply, a translating device supplied thereby, an electron tube controlling the continuity of said circuit thereof and having a control electrode, means to impress upon said electrode a potential rendering said tube conductive to effect completion of the circuit of said translating device, energy storing and discharging means associated with said electrode and having a transient effect thereon to cause said tube to thereof and having a control electrode, means to impress upon'said electrode a otential rendering said tube conductive to e ect completion of the circuit of said translating device, energy storing and discharging means asociated 'with said electrode and having a transient effect thereon to cause said tube to interrupt said circuit of said translating device, manual means and additional means associated with said translating device and in series with said manual means to commutate the connection of said energy storing means and means associated with said translating device to complete a circuit to effect discharge of said storing means upon interruption of said last mentioned circuit.

5. In combination, a power supply, a translating device supplied thereby, an electron tube controlling the continuity circuit thereof and having a control electrode, means to impress upon said electrode a potential derived from said supply for rendering said tube conductive to effect completion of the circuit of said translatingdevice, and energystoring and discharging means associated with said electrode and having a transient effect thereon to cause said tube to interrupt the circuit of said translating device for a given period, said first mentioned means including means to superpose a potential varying with the potential of said supply upon the control electrode during said given period.

6. In combination, an alternating current supply, a translating device-supplied thereby, an electron tube controlling the continuity of circuit thereof and having a control electrode, means to impress upon said electrode a potential derived from said supply for rendering said tube conductive to effect completion of the circuit of said translating device, and energy storing and discharging means associated with said electrode and having a transient effect thereon to cause said tube to interrupt the circuit of said translating device for a given period of time, said first mentioned means including means to super-pose an alternating potential which is in phase with the potential of said alternating circuit upon the control electrode during said given period.

7. In combination, a power supply, a translating device supplied thereby, an electron tube controlling the continuity of circuit thereof and having a control electrode, means to impress upon said electrode a potential rcndering said tube conductive to effect completion of the circuit of said translating device,

ener storing and discharging means associa with said electrode and havin a transient efiect thereon to causesaid tu e to interrupt said circuit of said translating device for a given period and means associated with said translating device to complete a circuit to efiect discharge of said storing means upon interruption of said last mentioned circuit, said first mentioned means including means to superpow a potential varying with the p0 .tential of said supply upon the control electrode durin said given period.

8. In com ination, a power supply, a translating device supplied thereb an electron tube controlling the continulty of circuit thereof and having a control electrode, means to impress upon said electrode. a tpotential rendering said tube conductive to e ect completion of the circuit of said translating device, energy storin and discharging means associated with said electrode and having a transient effect thereon to cause said tube to interrupt circuit of said translating device for a given period, means to commutate the connection of said ener storing means, means associated with sai translating device to complete a circuit to efl'ect discharge of said storing means upon interruption of the last mentioned circuit, said first mentioned means including means to superpose a potential varyin with the potential of sai supply upon t e control electrode during said given period.

9. In combination, an alternating current supply, a translating device supplied thereby, an electron tube controlling t e continuity of circuit thereof and having a control electrode, means to impress upon said electrode a ipotential rendering said tube conductive to ect completion of the circuit of said translating device, ener storing and discharging means associat with said electrode and having a transient efi'ect thereon to cause said tube tointerrupt circuit of said translating device for a given period, means to commutate the connection of said energy storing means, means associated with said translating device to complete a circuit to efiect discharge of said storin means upon interruption of the last mentioned circuit, said first mentioned means including means to superpose an alternating tential which is in phase with the potential of said alternatin supply upon the control electrode during sai given eriod. Y

10. 11 an electric welding system adapted to supply current to the material to be welded for an adjustable time, in combination, a power supply, a pair of welding jaws receiving energy from said supply, an electron tube controlling the continuity of circuit thereof and havin a control electrode, means to impress upon said electrode a potential for varying the conductivity of said tube to effect commutation of the circuit to said jaws, energy storing and discha means amociated with said electrodeand av' a transient efl'ect thereon to cause said tu to effect completion of the circuit to said jaws for a given riod of time and means associated with said first mentioned means to complete a circuit to effect dischar of said storing means upon completion 0 the circuit to said jaws.

11. In an electric welding system ada ted to supply current to the material to be we ded for an adjustable time, in combination, a

power supply, a pair of welding jaws receiving ener from said supply, an e ectron tube controlling the continuity of circuit thereof and having a control electrode, means to impress uponsaid electrode a otential rendering sai tube conductive to e ect interruption of circuit to said jaws, energy stori and dischargin means associated with sai electrode and to cause said tube to eflect completion of circuit to said jaws for a given period of time and means associated with said first mentioned means to complete a circuit to effect discharge of said storing means upon completion of the circuit to said jaws.

12. In an electric welding system ada ted to supply current to the material to be we ded for an adjustable time, in combination an alternating current supply, apair of welding jaws receivi ener t erefrom, an electron tube control ng t e continuity of circuit thereof and having a control electrode, means to impress upon said electrode a potential derived from said su ply for rendering said tube conductive to etibct interruption of the circuit to said jaws, energy storing and discharging means associated with said electrode and havin a transient efl'ect thereon to cause said tu to effect completion of the circuit to said jaws for a given time, said first mentioned means includin means to superpose an alternating tential which is in phase with the potentia of said alternating circuit upon the control electrode during said given period. t

13. In an electric welding system ada ted to supply current to the material to be we ded for an adjustable time, in combinatio an alternating current supply, a pair of wel ing jaws receiving ener from said supply, an electron tube contro ling the continuity of circuit thereof and having a control electrode, means to impress upon said electrode a potential rendering said tube conductive to effect interruption of circuit to said jaws, energy storingand discharging means associate with said electrode and havin a transient efi'ect thereon to cause said tu to effect completion of thecircuit to said jaws for a given period of time, means to commutate the connection of said energy storing means,

means associated with said energy storing aving a transient efiect thereon' and dischar ing means to complete a circuit to effect discharge of said storing means upon an initiation of current supply to said jaws, said first mentioned means including means to superpose an alternating potential which is in phase with the potential of said alternating supply upon the control electrode during said given period. 7

In witness whereof, we have hereunto subscribed our names.

CARROLL STANSBURY. GLEN DON 0. BROWN.