Electric heating – Metal heating – By arc
Reexamination Certificate
1999-01-07
2001-10-30
Shaw, Clifford C. (Department: 1725)
Electric heating
Metal heating
By arc
C219S130330
Reexamination Certificate
active
06310320
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the art of welding machines. More specifically, it relates to welding machines having two power supplies, and two welding outputs.
BACKGROUND OF THE INVENTION
Many different types of welding machines have been used in the prior art. One such prior art welding machine includes a full wave, three-phase, phase controlled welding power supply. For example, the Miller Dimension™ series of welding machines use a three-phase input and provide a constant current (CC) or a constant voltage (CV) output.
Another prior art welding machine is the Miller Big Blue™ 400D welding machine, which is an engine driven welding generator, and can also be operated in a CC output or CV output (with an added module). The output of this welding generator can be used directly to stick weld, or to provide power to a wire feeder for MIG welding.
Some engine driven welding machines include two power supplies driven by a single engine/generator. One example of this is the MQ Power Dualweld 400™. Generally, such dual output welding machines include the ability to select between an independent and combined mode. In the independent mode output power from the power supplies is provided independently to two pairs of output studs, and the machine effectively acts as two independent welding power supplies (both connected to a single generator). The controller includes two current magnitude selectors, one associated with a first output, and the other associated with the second output.
In the combined mode the outputs of both power supplies are combined, or placed in parallel, to form a single welding output. Thus, in this mode, the maximum output is twice that of the output in the independent mode of operation.
There are several drawbacks with the prior art dual output machines. First, when operating in the combined (parallel) mode, two output controls are used in the prior art to control a single output. This is because the output control for each power supply continues to control its respective power supply, even though the outputs are being combined to a single welding output. Thus, to balance the output between the two power supplies (which reduces the likelihood of overheating), one must adjust both output selectors to be in the same position.
Another disadvantage of dual output machines is that when operating in the combined (parallel) mode a CV output cannot be provided because the power supplies are parallel, and might not share the current. The prior art overcomes this problem by not providing a CV output in dual output, phase controlled, machines (even when the machine is operating in the independent mode).
Another prior art dual welding machine includes a generator used to power one or more inverters. The inverters are operated independent of one another, and cannot have their outputs combined to provide a relatively greater magnitude output in CV mode.
Accordingly, a dual output welding machine that provides for a single control of the output when operating in the combined mode is desirable. Additionally, such a welding machine will preferably be capable of providing a CV output when operating in the independent mode.
Many engine driven/generator welding power supplies have a drooping VA curve, wherein as the current increases, the output from the weld windings decreases. Accordingly, an engine driven/generator welding power supply that compensates for a drooping VA curve, by increasing the voltage when the current increases, is desirable.
SUMMARY OF THE PRESENT INVENTION
According to a first aspect of the invention a welding machine includes two power sources (first and second), each having an output. A linking circuit selectively connects the power sources in an independent mode such that each is connected to a separate welding output, whereby the first welding output is independent of the second welding output. Also, the linking circuit can selectively connect the power sources in a combined mode such that the power sources are connected in parallel and connected to one welding output, whereby the outputs of the first power source and second power source are combined. A controller is connected to the linking circuit. The controller includes a mode selector to allow the user to select between the independent mode and the combined mode. Also, the controller includes a master output magnitude selector, which is a single selector, that controls the magnitude of the output of both power sources when the user has selected the combined mode.
A second aspect of the invention is an engine and generator driven welding machine that includes first and second phase controlled power sources, with first and second welding outputs. A linking circuit is disposed to select one of a CC output and a CV output. A controller is connected to and controls the linking circuit such that the user may select between the CC output and the CV output.
A third aspect of the invention is an engine, a generator (including a rotor) connected to and driven by the engine, and a phase controlled power source connected to receive power from the generator. A controller is connected to the power supply and the generator, and includes a load compensation circuit to control the field current in the rotor.
The controller includes a slave output magnitude selector which controls the output of the second power source when the independent mode is selected and the master output magnitude selector controls the magnitude of the output of the first power source when the independent mode is selected, in another embodiment.
The controller includes a master magnitude circuit and a slave magnitude circuit in another embodiment. The master output magnitude selector provides an input to the master magnitude circuit in either mode, and the master output magnitude selector provides an input to the slave magnitude circuit only when the combined mode is selected. The slave output magnitude selector provides an input to the slave magnitude circuit when the independent mode is selected in yet another embodiment. The magnitude selectors includes master potentiometers in another variation.
The power sources receive power from an engine and generator in one embodiment. The generator includes a rotor, and wherein the controller includes a load compensation circuit to control the field current in the rotor in another version.
The power sources are phase controlled, full wave, and/or three phase power sources in various embodiments. Also, the power sources may provide a CC output when in the combined and independent modes, and may provide a CV output when in the independent mode in another embodiment.
In yet another embodiment the linking circuit includes a switch to select between the CV output and the CC output. The CV/CC switch is controlled by the controller. Also, a mode select switch to select between independent and combined modes. The mode switch is controlled by the controller. The controller controls the switches such that if the CV output is selected the second switch cannot implement the combined mode.
A disable circuit is provided in another embodiment and it disables the output when the combined mode is selected and a CV output is selected in another embodiment.
Another aspect of the invention is a method of providing welding power and includes providing power from a first source and a second source. The power sources are selectively connected in an independent mode in which the power from the first source is provided to a first output and the power from the second source is provided to a second output, whereby the first output is independent of the second output, or they are selectively connected in a combined mode in which the power from the first source is provided to the first output and the power from the second source is provided to the first output, whereby the outputs of the first power source and second power source are combined. The magnitude of both power sources are controlled in response to a single user controlled selector, when in the combined mode.
Another aspect is a metho
Bunker Thomas
Kraus David
Corrigan George R.
Illinois Tool Works Inc.
Shaw Clifford C.
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