US3889178A - Welding control circuit and method - Google Patents
Welding control circuit and method Download PDFInfo
- Publication number
- US3889178A US3889178A US381473A US38147373A US3889178A US 3889178 A US3889178 A US 3889178A US 381473 A US381473 A US 381473A US 38147373 A US38147373 A US 38147373A US 3889178 A US3889178 A US 3889178A
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- voltage
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- welder
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- G—PHYSICS
- G05—CONTROLLING; REGULATING
- G05F—SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- G05F1/00—Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
- G05F1/10—Regulating voltage or current
- G05F1/12—Regulating voltage or current wherein the variable actually regulated by the final control device is ac
- G05F1/40—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices
- G05F1/44—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only
- G05F1/445—Regulating voltage or current wherein the variable actually regulated by the final control device is ac using discharge tubes or semiconductor devices as final control devices semiconductor devices only being transistors in series with the load
Definitions
- a voltage regulator and method are utilized in an au- 4 Rained Apphcatmn Data tomatic throttle control for an internal combustion en- [63] Commuano of 71613, Sept' 1971 gine driven inductor alternator. An SCR in series with abandoned the load is biased to conduct on successive positive Us. (1.0032302 219/131 219/133; half-cycles of a rectified a.c. input voltage.
- the SCR O7 323 36 323/39 conductive bias is opposed responsively to the load 307/265 307/293 3 fig B23k 9/06 voltage so that the average load voltage is a function [51] i 21 2 22 SC 36 of the number of complete pulses of the source in [58] figg gi i 4 31 R which the SCR conducts during a given time period.
- a hold-off circuit is provided to prevent SCR conduction WR, 307/296, 293, 297, 265, 322/28 during welding [56] References Cited 20 Claims, 4 Drawing Figures UNITED STATES PATENTS 3,339,114 8/1967 Kelley et al.
- This invention relates to voltage regulators and more specifically to a voltage regulator particularly adapted for use with a small portable internal combustion engine powered inductor alternator.
- Portable generators of this type are well known in the art.
- the output winding of the alternator is generally capacitatively compensated so that the internal impedance of the alternator, as seen from the arc welding load, is substantially resistive.
- Systems of this type normally have two electrical leads which are directly connected to the welding electrode and the work piece.
- a pneumatic valve located at the electrode holder has been used to operate the throttle control of the Z-cycle internal combustion engine utilized to drive alternator.
- Two pneumatic lines to the valve are customarily physically secured to the electrical lead to the welding electrode holder where the valve may be manually operated by the welder.
- the air pressure generally utilized for operating prior art pneumatic controls of this type is derived from the pressure within the crankcase of the internal combustion engine.
- Welding current is, of course, a function of the speed of the alternator and current control is achieved by varying the setting of the governor of the engine so that the alternator is driven at a predetermined speed to produce the required current. The engine is then selectively operated either at the governed speed or at idle as manually determined by the welder.
- an inductor alternator generally retains a small amount of residual magnetism and, although the engine is idling at a speed below the excitation speed of the generator, a small voltage is generated due to this residual magnetism.
- the grounding or the striking of the electrodes by the weldor significantly reduces this small voltage and the reduction in voltage can be sensed to effect operation of the internal combustion engine throttle.
- the demand for current which accompanies the striking of the welding are may also be sensed to effect the operation of the engine throttle.
- the McCulloch Model No. 170 Arc Welder produces, from the minimum-to-maximum governor settings and from no load to a short circuit condition, an ac. armature voltage variation of about 30 to about 160 volts r.m.s. with a corresponding field voltage variation of about 20 to about 130 volts do
- a typical pop-in load with the minimum-to-maximum governor settings will produce an armature voltage variation of about 30 to about volts ac. and a field voltage variation of about 30 to 95 volts do
- One approach of the prior art has been the design of a solenoid which would operate over these varying voltages.
- Variable phase control means such as hyratrons and their solid state equivalents, silicon controlled rectifiers, have been proposed. Such systems have utility only where the frequency of the source is stable since the phase angle between the anode-cathode potential and the triggering or conduction initiating signal is critical. Since the frequency of the inductive alternator signal may vary by as much as a factor of four the usefulness of this type of control is quite limited.
- an object of the present invention to obviate the difficiencies of the prior art and to provide a novel method and automatic control for an internal combustion engine driven alternator.
- Still a further object of the present invention is to provide a novel voltage regulator and method operable over a 4-to-1 variation in speed of the alternator producing the input voltage.
- Yet a further object of the present invention is to provide a novel voltage regulator and method in which the output voltage is a function of the number of integral half-cycles of the voltage source.
- FIG. 1 is a functional block diagram of the system of the voltage regulator of the present invention
- FIG. 2 is a graph showing the variation in output voltage of the voltage regulator of FIG. 1 with respect to variations in input voltage and alternator speed;
- FIG. 3 is a schematic circuit diagram of a preferred embodiment of the voltage regulator of FIG. 1 as utilized in a welder.
- FIG. 4 is a schematic illustration of a welder utilizing the circuit of FIG. 3.
- a source of alternating current 10 is shown schematically in series with a silicon controlled rectifier (SCR) 112 and a load impedance 14.
- Means 16 are provided for biasing the trigger electrode of the SCR with sufficient dc. voltage so that the SCR is turned on every half-cycle or, if selfrectifying as shown in the drawing, every other half cycle of the a.c. source 10.
- the level of the bias provided the trigger electrode of the SCR 12 by the bias means 16 may be selectively adjusted by varying the voltage of a dc. reference 18.
- a sensor 20 is provided to sense the voltage across the load impedance 14 and to adjust, in response thereto, the additional bias to the trigger electrode of the SCR 12 provided by the control bias means 22 in opposition to the bias from the dc. means 16.
- the control bias means 22 is operative to prevent the SCR from turning on for a particular positive half-cycle of the source 10.
- the SCR 12 can conduct only when the anode is positive with respect to the cathode. Once conduction is initiated by the application of voltage of the requisite magnitude to the trigger electrode, the SCR 12 will conduct until the necessary anode to cathode bias is removed.
- the (Le. bias means 16 is effective to initiate conduction of the SCR 12 during each of the positive half-cycles of the source 10. Conduction of the SCR 12 is extinguished during the negative half-cycles of the source 10. While the source 10 illustrated provides an a.c. signal, the signal applied across the SCR l2 and load impedance 14 may be any series of current pulses such as an interrupted d.c. signal, a.c. signal or a full or half-wave rectified a.c. signal. The signal must provide sufficient anode to cathode bias for SCR conduction, and the level of this anode to cathode bias must from time to time drop below this critical conduction level to interrupt the conduction of the SCR.
- the present invention utilizes the SCR 12 as a switch to suppress conduction during complete positive half-cycles of the source 10.
- the voltage across the load 14 may be filtered as desired and regulation of the average load voltage achieved by varying the number of complete halfcycles of the current from source 10 which are applied thereto in a given time period.
- the average output or regulated voltage v across the load 14 has been held to within a few millivolts of a desired value during a frequency variation of the source 10 or from about 800 Hz. to about 3200 Hz. at a voltage variation of the source 10 of from about 20 volts rms to about 200 volts rms.
- FIG. 3 wherein the voltage regulator illustrated in FIG. 1 is illustrated as an automatic throttle control for an internal combustion engine driven inductor alternator, the armature winding 23 of the alternator is shown connected to a pair of welding electrode terminals 24 and 26.
- the alternator may be, for example, the McCulloch Corporation Model 170 Welder, the circuitry of which is disclosed in the Jackson Letters Pat. No. 3,204,173 and herein incorporated by reference.
- a compensating capacitor 28 typically microfarads, is connected in the electrical lead 30 so that the impedance of the alternator, as seen from the terminals 24 and 26, is substantially resistive.
- the voltage from an a.c. source 23 may be full wave rectified in a conventional diode bridge 32 and applied across an SCR 34 and an inductive load impedance 36.
- the load impedance 36 serves as the actuating coil of a solenoid utilized to control the throttle of the internal combustion engine which drives the alternator.
- the full wave rectifier 32 may be replaced by a half wave rectifier or the rectification inherently provided by the SCR may be utilized if conduction during every second half-cycle of the source 23 is acceptable.
- the load impedance 36 may be either resistive or inductive as shown in FIG. 3 but cannot be capacitive unless isolated from the cathode of the SCR by a diode so that the voltage on the capacitive load is not reflected back to the cathode of the SCR to prevent the conduction thereof.
- a capacitor 38 may be connected through a diode 40 across the terminals 42 and 44 and the inductor 36 omitted.
- the capacitor 38 may, of course, be utilized as a filter to provide a regulated voltage on a pair of output terminals 46 and 48.
- the SCR 34 and load impedance 36 are paralleled by a voltage divider network comprising a resistor 50, a Zener diode 52, and a resistor 54.
- the resistor 50 Zener diode 52junction 56 is connected through a current limiting resistor 58 to a terminal 60 of the trigger electrode of the SCR 34.
- the terminal 60 i.e., the trigger electrode of the SCR 34, is also connected to the cathode of the SCR 34 through a resistor 62.
- the load 36 is paralleled by a diode 64 and capacitor 66 and the cathode of the SCR 34 is connected through a resistor 68 in parallel with a capacitor 70 to the resistor 54 Zener diode 52 junction 72.
- the capacitor 66 is necessary for inductive or resistive loads but the diode 64 may be eliminated for a resistive load. As earlier explained, the alternating current input may be full or half-wave rectified, but must be periodically returned to zero to quench the conduction of the SCR 34.
- the resistor 68 capacitor 70 parallel combination serves with the resistor 54 as a voltage divider across the load impedance 36 and as a filter with a relatively long-time constant to provide a dc. bias for the SCR 34.
- the capacitor 70 is charged by the load voltage. This voltage appears substantially across the Zener diode 52 and the resistor 62, since the voltage drop across current limiting resistor 58 is quite small. An increase in the voltage across the load impedance 36 will provide a bias to the trigger electrode of the SCR 34 to prevent the conduction thereof.
- the forward or conductive bias applied to the trigger electrode 60 of the SCR 34 may be selectively varied by the use of a switch 67 and/or a sliding contact 69 on the resistor 54.
- an additional holdoff circuit may be provided as illustrated in FIG. 3.
- the hold-off circuit includes a diode 73 and capacitor 74 connected in parallel and connected between the alternator winding 23 and compensating capacitor 28 and. is operative to apply the alternator a.c. output voltage potential to the trigger electrode of the SCR 34 through a small current limiting resistor 76.
- an internal combustion engine 80 drives an inductive alternator 82 by means of a shaft 84.
- the throttle valve 86 in the intake line 88 is controlled between an idle position where the throttle actuating arm 90 abuts a mechanical stop 92 and a fully on position where the arm 90 abuts a variably positioned mechanical stop 94.
- the position of the stop 94 determines the speed of the engine and thus the welding current provided by the alternator 82 to the welding electrode terminals 24 and 26.
- the throttle arm 90 is spring biased into the fully on position against the stop 94.
- the voltage produced by the alternator is operative through the voltage circuit 96 illustrated in FIG. 4 to provide the energization of the solenoid coil 36 thereby extending the rod 95 to hold the throttle arm 90 in the idle position against the stop 92.
- the hold-off circuit 98 of FIG. 4 is operative to sense the welding current and to override the voltage circuit 96 and to de energize the solenoid coil 36.
- the solenoid is acti vated and the engine 80 operates at idle speed only when the engine 80 is running and welding is not in progress.
- the circuit of FIG. 3 thus distinguishes between an open circuit and a closed circuit with welding in progress.
- the speed of the alternator and thus the amplitude and frequency of the voltage from the alternator may vary from some maximum immediately after extinguishing the welding arc to some minimum after the alternator speed has been reduced.
- the solenoid must thus be operable under extreme frequency and voltage variations to position and to hold the throttle at the idle position.
- the regulator of the present invention is effective to maintain the desired solenoid voltage under these varying conditions.
- the engine throttle is open for engine starting, closes automatically to idle speed after the engine is started, and automatically opens when the welding arc is struck.
- the utilization of the novel voltage regulator disclosed permits the energization of the throttle solenoid from the alternator with widely varying voltage, current and frequency parameters. The power dissipation problems associated with dissipative regulation systems and the frequency dependency of phase control system are thus avoided. Moreover, solenoid sensitivity can be maintained without severe problem of power dissipation therein.
- the voltage regulator of the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof.
- the presently disclosed embodiment is, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are, therefor, intended to be embraced therein.
- the degree of regulation may be enhanced by thecascading of SCRs to provide the desired degree of sensitivity and current carrying capacity generally limited in large cur rent carrying devices.
- a voltage regulator comprising:
- said load impedance includes an inductor and a diode in parallel.
- said load impedance includes a capacitor and a diode in series.
- said source of current pulses comprises a source of alternating current in series with a full wave rectifier.
- said means for biasing comprises a voltage divider network connected in parallel across said switch means and said load impedance, said network including a Zener diode.
- the voltage regulator of claim 1 including means for selectively modifying the bias provided by said means for biasing to thereby modify the level of the regulated voltage.
- switch means is an SCR and wherein the trigger electrode of said SCR is connected to the cathode thereof through a circuit element having a predetermined value of resistance.
- said means for biasing comprises a voltage divider network connected in parallel across said SCR and said load impedance, said network including a Zener diode;
- said source of current pulses comprises a source of alternating current in series with a full wave rectifier.
- a method of voltage regulation comprising the steps of:
- a welder comprising:
- an SCR and an inductor in series across said electri cal conductors; means for sensing the voltage across said inductor; means for conductively biasing said SCR during like half-cycles of current from said source; and, means responsive to said inductor voltage sensing means for opposing said conductive bias.
- the welder of claim 12 wherein the frequency of 15.
- the welder of.claim 12 including means respon-,
- said conductionpreventing means includes:
- delay means for prolonging the prevention of the conduction of said SCR for a predetermined time period subsequent to the loss of current through said electrical conductors.
- the welder of claim 12 including a diode connected across said inductor and wherein the conduction bias and the conduction-opposing bias are applied to the trigger electrode of said SCR.
- the welder of claim 12 including full wave rectifier means for connecting said SCR and said inductor across said electrical conductors.
- said conduction biasing means includes a voltage divider network connected in parallel across said SCR and said load impedance, said network including a Zener diode.
- the welder of claim 12 including means for selectively modifying the bias provided by said SCR conduction biasing means.
Abstract
Description
Claims (20)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US381473A US3889178A (en) | 1971-09-03 | 1973-07-23 | Welding control circuit and method |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US17761371A | 1971-09-03 | 1971-09-03 | |
US381473A US3889178A (en) | 1971-09-03 | 1973-07-23 | Welding control circuit and method |
Publications (1)
Publication Number | Publication Date |
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US3889178A true US3889178A (en) | 1975-06-10 |
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US381473A Expired - Lifetime US3889178A (en) | 1971-09-03 | 1973-07-23 | Welding control circuit and method |
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US (1) | US3889178A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5968385A (en) * | 1997-05-19 | 1999-10-19 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
AU725788B2 (en) * | 1997-05-19 | 2000-10-19 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US20060157459A1 (en) * | 2005-01-20 | 2006-07-20 | Fosbinder Daniel C | System and method of controlling auxiliary/weld power outputs of a welding-type apparatus |
Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3339114A (en) * | 1965-02-19 | 1967-08-29 | Ite Circuit Breaker Ltd | Static overload relay means for use in circuit breakers and having inverse time current characteristics |
US3506852A (en) * | 1967-03-10 | 1970-04-14 | Barber Colman Co | Method and apparatus to provide zero angle firing of a static latching switch in a noise-free electric controller |
-
1973
- 1973-07-23 US US381473A patent/US3889178A/en not_active Expired - Lifetime
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3339114A (en) * | 1965-02-19 | 1967-08-29 | Ite Circuit Breaker Ltd | Static overload relay means for use in circuit breakers and having inverse time current characteristics |
US3506852A (en) * | 1967-03-10 | 1970-04-14 | Barber Colman Co | Method and apparatus to provide zero angle firing of a static latching switch in a noise-free electric controller |
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030075927A1 (en) * | 1997-05-19 | 2003-04-24 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US5968385A (en) * | 1997-05-19 | 1999-10-19 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US6111217A (en) * | 1997-05-19 | 2000-08-29 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
AU725788B2 (en) * | 1997-05-19 | 2000-10-19 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US6310321B1 (en) * | 1997-05-19 | 2001-10-30 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US6469401B2 (en) | 1997-05-19 | 2002-10-22 | Illinois Tool Works Inc. | Engine driven welding power supply with inverter auxiliary power |
AU714274B2 (en) * | 1997-05-19 | 1999-12-23 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US6674179B2 (en) | 1997-05-19 | 2004-01-06 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US20050236383A1 (en) * | 1997-05-19 | 2005-10-27 | Illinois Tool Works Inc. | Engine driven converter with feedback control |
US6894401B2 (en) | 1997-05-19 | 2005-05-17 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US20040060912A1 (en) * | 1997-05-19 | 2004-04-01 | Illinois Tool Works Inc. | Engine driven inverter welding power supply |
US7112945B2 (en) | 1997-05-19 | 2006-09-26 | Illinois Tool Works Inc. | Engine driven converter with feedback control |
US20060157459A1 (en) * | 2005-01-20 | 2006-07-20 | Fosbinder Daniel C | System and method of controlling auxiliary/weld power outputs of a welding-type apparatus |
US7858904B2 (en) | 2005-01-20 | 2010-12-28 | Illinois Tool Works Inc. | System and method of controlling auxiliary/weld power outputs of a welding-type apparatus |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: MCCULLOCH CORPORATION A MD CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:BLACK & DECKER INC., A DE CORP.;REEL/FRAME:004134/0336 Effective date: 19830505 |
|
AS | Assignment |
Owner name: CITICORP INDUSTRIAL CREDIT, INC., 450 MAMARONECK A Free format text: MORTGAGE;ASSIGNORS:MC CULLOCH CORPORATION;MC CULLOCH OVERSEAS N.V.;REEL/FRAME:004158/0190 Effective date: 19830331 Owner name: CITICORP INDUSTRIAL CREDIT, INC., NEW YORK Free format text: MORTGAGE;ASSIGNORS:MC CULLOCH CORPORATION;MC CULLOCH OVERSEAS N.V.;REEL/FRAME:004158/0190 Effective date: 19830331 |
|
AS | Assignment |
Owner name: FIRST UNION NATIONAL BANK OF NORTH CAROLINA ONE F Free format text: SECURITY INTEREST;ASSIGNOR:MCCULLOCH CORPORATION;REEL/FRAME:005337/0736 Effective date: 19900530 Owner name: MCCULLOCH CORPORATION, A CORP. OF MD. Free format text: RELEASED BY SECURED PARTY;ASSIGNOR:CITICORP NORTH AMERICA, INC., FORMERLY KNOWN AS CITICORP INDUSTRIAL CREDIT, INC.;REEL/FRAME:005365/0004 Effective date: 19900530 |