US1867225A - Timing device - Google Patents

Description

July 12, 1932. J, 13, LE VAN ET AL 1,867,225

TIMING DEVICE Filed Jan. 2, 1930 Patented July 12, 1932 UNITED STATES PATENT OFFICE JAMES D. LE VAN, OF MILWAUKEE, AND CARROLL STANSBURY, F WAUWA'IOSA, WIS- CONSIN, ASSIGNORS TO CUTLER-HAMMER, 1NC., OF MILWAUKEE, WISCONSIN, A

CORPORATION OF DELAWARE TIMING Application filed January 2,

The invention relates to the control of currents by means of electron tubes.

An object of the invention is to provide for the control of such tubes so as to pass therethrough a controlled current intermittently for an adjustable period of time.

Another object is to provide apparatus for commutating the current supplied to a translating device during an adjustable period.

Another object is to provide apparatus for accurately timing an interval during which current is supplied to a translating device.

Other objects will appear from the description and appended claims.

The accompanying drawing illustrates a mode of carrying out the invention.

Figure 1 is a diagram of the circuit ar rangement illustrating the operation of the invention, while Fig. 2 is a diagram showing the application of the invention to an electric welder. v

Hot cathode electron tubes of the grid type are conducting when the negative potential of the grid with respect to the cathode does-not exceed a given value and the flow of current between the cathode and anode may be stopped or may be prevented from starting by the application to the grid of a higher negative potential. Current between the cathode and anode can only flow when the cathode is negative with respect to the anode, so that such tubes when employed in alternating current circuits act as rectifiers and pass only alternate half waves of the alternating current.

. With high vacuum tubes the current from the cathode to the anode may be stopped by making the grid sufficiently negative with respect to the cathode, whether the voltage impressed upon the electrodes is direct or alter nating current. That is to say, during the working half cycle when the cathode is nega-- tive the grid potential must not exceed a certain negative value or must be positive with respect to the cathode to permit a flow of current.

On the other hand, with gaseous tubes the flow of current between the cathode and anode cannot be stopped by a negative grid potential during the half cycle after it has DEVICE 1930. Serial No. 417,969. once been started. To keep the tube from starting during any half cycle asufficiently high negative potential must be impressed upon the grid during that half cycle.

The present invention is applicable to either a direct or alternatingcurrent power supply.

According to the present invention the grid is normally positive with respect to the oathode when the latter is negative so that current flows to the anode and means are provided whereby the positive potential of the grid is reduced or is changed to a negative potential for an adjustable period to keep the tube in the non-conducting condition during the desired period.

Fig. 1 will now be explained on the assumption that the power supply is direct current and the tube is a high vacuum tube, but as stated above the system is also operative with alternating current.

L 2 are the direct currentpower supply lines. 2 is a translating device, thecurrent through which is to be regulated by means of the electron tube 3, having a cathode 4, an anode 5 and a grid 6. The cathode 4 may be heated by current from any suitable source in any well known manner. Connected to the grid is a condenser 7 which is shunted by an adjustable resistance 8. The condenser inturn is connected through a resistance 9 to the cathode 4 and line L and under normal conditions through the normally closed switch 10 by wire 13 to the line L.

The apparatus functions in the following manner: 7

When the switch 10 is closed a current flows between the cathode 4 and the grid 6, the current flowing from line L through wires 11 and 13, switch 10 and resistance 8 to grid 6 and hence over cathode 4 and wire 12 to line L while another current branches ofi rent flow to the grid from line L will be stopped and the grid will become negative with respect to the cathode 4 due to the negative charge accumulated on the side of the condenser which is connected to said grid. This stops the flow of current between the main electrodes and through the translating device. The condenser will immediately begin to discharge through the resistance 8, thus reducin the negative potential on the grid 6 until, a ter a definite time interval, which is adjustable by adjusting the resistance 8, the grid potential has been reduced to zero, thus rendering the tube again conducting.

The switch 10 may now be closed again, whereupon the condenser 7 will be again charged and the described cycle repeated. It will thus be seen that by the opening of the switch 10 the current passing between the anode and cathode and thus through the translating device 2 may be interrupted for a definite and adjustable time interval.

Fig. 2 illustrates the application of the invention to an electric welding machine. In an electric welder it is desirable to apply a given current to the weld for a definite time, the time depending upon the character and thickness of the material which is to be welded, and other considerations, and the apparatus illustrated by Fig. 2 is designed to accurately regulate the time during which current is applied to the weld. In the drawing I and L are the alternating current power supply lines, furnishing power to a welding transformer 20 having a primary winding 21 and a secondary winding 22. The ends of the secondary winding are connected to the welding terminals 23 of a suitable type of welding machine. A magnet switch 24 having a magnet winding 25, an armature 26 and normally open contacts 27 controls the current supply to the winding 21.

The normally open magnet switch 24 is in turn controlled by a magnet switch 28 having a magnet winding 29, an armature 30 and normally closed contacts 31. The magnet winding 29 is in turn controlled by the electron tube 32 having a cathode 33, an anode 34 and a grid 35. In series with the grid is an adjustable resistance 36 which is paralleled by a condenser 37. The other side of the resistance 36 is connected to an adjustableresistance 38 which in turn is connected to the cathode 33. Resistance 36 is also connected through a resistance 39 to a normally closed switch 40, which is mechanically connected with the movable element of the jaws 23, so that when the jaws 23 open the switch 40 is closed and vice versa.

The apparatus operates in the following manner:

With an alternating current impressed upon the lines L -L and the jaws 23 of the welder open the switch 40 is closed so that a circuit is established from the line the line L.

rent therefore flows from the line L through 29 of relay 28, the anode 34 the winding The to the cathode 33 back to line L energization of the magnet winding 29 at tracts the armature 30, thus opening the contacts 31 so that no current can flow through the coil 25 of the magnet switch 24 and hence the armature 26 remains unattracted and contacts 27 remain open and no current flows through the primary winding 21 of the welder 20. If now the jaws 23 are closed on the material to be welded, the switch 40 is opened and the opening of such switch disconnects the resistance 39 and hence the grid 35 from The grid thereupon becomes negative due to the negative charge on the side of the condenser which is directly connected to the grid and thus makes the tube 32 non-conducting, resulting in deenergization of the switch 28 and closure of the contacts 31 which in turn causes energization of the coil 25 of ma net switch 24 and closure of contacts 27 so that now the transformer primary winding 21 is connected across the lines IP-L and current is induced in the secondary winding 22 and supplied to the Welging jaws 23 to bring about the desired we The condenser 37 gradually discharges through the resistance 36, the time of discharge being ad'ustable through adjustment of the value 0 resistance 36. Ultimately when the potential of grid 35 has reached zero value, the tube again becomes conductive during the half cycle when the line L is positive, resulting in opening of switch contacts 31 and deenergization of the magnet switch 24 and opening of contacts 27 which interrupts the current in the transformer and terminates the flow of welding current through the jaws 23. The apparatus remams in this position until-the jaws are again separated and the switch 40 closed and subsequently opened when the cycle is repeated.

to interrupt the circuit of said translating device for a given period of time.

2. In combination, a power supply, a translating device, an electron tube controlling the continuity of circuit thereof and having a control electrode, an impedance and a parallel resistance connected in series with said control electrode, a second impedance in series with said first impedance and connected to an electrode of said tube, a switch for connecting said last mentioned impedance across the power supply and to interrupt such connection for varying the potential impressed upon the control electrode and the first impedance, and to control the conductivity of the tube in accordance with a transient voltage resulting from such variation.

3. In combination, a translating device, an electron tube controlling the continuity of circuit thereof and having a control electrode, an impedance and a parallel resistance connected in series with said control electrode, means to impress a potential upon said resist ance and said control electrode to render the tube conductive to effect completion of the circuit of said translating device, said means being 0 erative thereafter to alter said potential and to affect the potential of said grid by a transient voltage resulting from such alteration to interrupt the continuity of circuit of said translating device for a given time interval.

4. In combination, a power supply, a translating device and an electron tube having a control electrode, said translating device and said tube being connected in circuit with said power supply, two adjustable resistances connected in series between one side of the power supply and the control electrode, a condenser in parallel with one of said resistances and a switch connected between the other resistance and the other side of the power supply and adapted to vary the potential impressed upon said resistances, to thereby produce a transient potential on the control electrode for affecting the conductivity of the tube.

5. In an electric welding system adapted to supply current to the material to be welded for an adjustable time, incombination a power supply, a pair of relatively movable welding jaws receiving energy from said supply, an electromagnetic switch for controlling the supply of current to said jaws, an electromagnetic relay for controlling said switch, the windings of said switch and said relay being adapted to receive power from said supply, an electron tube in circuit with the winding of said relay, a resistance and a parallel condenser connected with a control electrode of said tube, a second resistance connected in series between the condenser and one side of said power supply and a switch mechanically connected to said jaws and movable with the latter, adapted to normally connect the electromagnetic relay-for controlling said switch, the windings of said switch and said relay being adapted to receive power from 'said supply, an electron tube in circuit with the winding of said relay, a resistance and a parallel condenser connected with a control electrode of said tube, a second resistance connected in series between the condenser and one side of said power supply and a switch mechanically connected to said aws and movable with the latter, adapted to normally connect the condenser end of said second resistance to the other side of the power supply and to disconnect it therefrom when the jaws are moved towards each other.

7 In an electric welding system adapted to supply to the material to be welded current 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 having a control electrode, means to impress upon said electrode a potential for varying the conductivity of said tube to' effect commutation of circuit to said jaws and energy storing and discharging means associated with said electrode and having a transient eflect thereon to cause saidtube to effect completion of the circuit to said jaws for a given period of time.

8. In 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 having a control electrode, means to impress upon said electrode a potential rendering said tube conducting to effect interruption of circuit to said jaws, and energy storing and discharging means associated with said electrode and having a transient effect thereon to cause said tube to efiect completion of the circuit to said aws for a given period of time.

9. In 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 having a control electrode, an impedance and a parallel resistance connected in series with said control electrode, a second impedance in series with said first impedance and connected to an electrode of said tube, a switch for connecting said last mentioned impedance across the power supply and to interrupt said connection for varying the potential impressed upon the control electrode and the first impedanceand to control the conductivity of the tube in accordance with a transient voltage resulting from such variation.

10. In 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 ener from said supply, an electron tube controlling the continuity of circuit thereof and having a control electrode, an impedance and a parallel resistance connected in series with said control electrode, means to impress a potential upon said resistance and said control electrode to render the tube conducting to effect completion of said circuit, said means being operative thereafter to alter said potential and to affect the potential of said grid by a transient voltage resulting from such alteration to complete the circuit to said jaws for a given time interval.

11. In 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 jaws receiving energy from said supply and an electron tube having a control electrode, said jaws and said tube being connected in circuit with said power supply, two adjustable resistances connected in series between one side of the power supply and the control electrode, a condenser in parallel with one of said resistances and a switch connected between the other resistance and the other side of the power supply and adapted to vary the potential impressed upon said resistances to thereby produce a transient potential on the control electrode for affecting the conductivity of the tube.

In witness whereof, we have hereunto subscribed our names.

JAMES D. LE VAN. CARROLL STANSBURY.

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