JPH0519180Y2 - - Google Patents

Description

[Detailed Description of the Invention] "Industrial Application Field" The present invention relates to an engine-driven welding machine, and particularly to an improvement of a welding machine equipped with an AC auxiliary power output.

``Prior Art'' In general, engine-driven welding machines equipped with an AC auxiliary power source, which can also be used as a power source for lighting and power tools for incidental work, are widely used at outdoor work sites where commercial power is difficult to obtain. It's reached.
Moreover, in recent years, the engine-driven melting machines have tended to have larger capacity AC auxiliary power supplies as the work content has diversified. On the other hand, since such engine-driven welding machines are frequently moved and used, they are required to be small and lightweight.
For these reasons, when welding work in a small current range these days, we use an AC auxiliary power supply with a capacity commensurate with the large surplus engine output, and when welding work is stopped, we use a large capacity AC auxiliary power supply commensurate with the full engine output. There is an increasing use of AC auxiliary power source outputs that can be tapped.

As shown in Fig. 2, an engine-driven welding machine equipped with this type of AC auxiliary power source has a main armature winding 1 for the welding power source, an auxiliary armature winding 2 for the AC auxiliary power source, and a field winding. An alternating current generator 4 consisting of a line 3 is driven by an engine (not shown). The three-phase AC output of the main armature winding 1 is the output DC setting device 1.
It can be adjusted to a desired value according to the welding conditions by changing the current supplied to the field winding 3 in step 2, and after rectifying it in rectifier 5, it is connected to arc load 8 through output terminals 6 and 7. It is starting to supply electricity. On the other hand, the AC output of the auxiliary armature winding 2 is configured to supply AC auxiliary power output to an AC load 11 such as a lighting or a power tool via output terminals 9 and 10. The correlation between the usable range of the AC auxiliary power output with respect to the above welding output is shown in the third section.
It is as shown in the figure. In other words, the welding output is
It is the product of the welding output current and the arc voltage, but since the arc voltage is approximately constant, it can be considered to be approximately proportional to the welding output current, so the welding output current changes from I ₁ to I ₂ , I ₃ , As I increases to ₄ , the required output for the engine also increases from Pe1 to Pe ₂ , Pe ₃ , Pe ₄
and increases. Therefore, the AC auxiliary power output can be used by the amount remaining after subtracting the welding output for the set value of the welding output current from the maximum engine output.

``Problems to be solved by the invention'' However, in this type of welding machine shown in Figure 2, neither the welding output nor the AC auxiliary power output is equipped with any means of limiting, and the operator However, if the total output exceeds the maximum output of the driving engine by mistake, there have been cases where the speed decreases, the engine stops, etc., and work efficiency is significantly hindered.

Therefore, in view of the above circumstances, the present invention determines and automatically regulates the usable AC auxiliary power output from the welding output that varies depending on the welding conditions.
It is an object of the present invention to provide an engine-driven welding machine that can prevent engine overload by cutting off the power supply to the AC load when the power supplied to the AC load exceeds the regulation value.

"Problems to be Solved by the Invention" In order to achieve the above object, the present invention is driven by an engine and includes a main armature winding for a welding power source and an auxiliary armature winding for an AC auxiliary power source. In an engine-driven welding machine that has a generator equipped with a welding output setting device on the output side of the main armature winding of the generator and a cutoff device on the output side of the auxiliary armature winding, An output detector is interposed on the output side of the armature winding, and the welding output setting device generates a variable regulation signal whose value changes in response to the output setting value, and the variable regulation signal and the output The engine-driven welding machine is characterized by interposing an auxiliary power output regulating device for controlling the cutoff device by comparing the value with a detection signal of a detector.

"Function" In the above-mentioned means, the present invention stipulates the allowable output value of the AC auxiliary power source in correspondence with the set value of the welding output in the auxiliary power output regulating device, and outputs the AC load from the auxiliary armature winding. When the supplied power exceeds a specified value in the auxiliary power output regulating device, the auxiliary power output regulating device operates a cutoff device,
This is designed to cut off the power supply from the auxiliary armature winding to the AC load.

"Embodiment" An embodiment of an engine-driven welding machine according to the present invention will be described below with reference to the drawings. In FIG. 1, 21 is an alternating current generator. The alternator 21
consists of a three-phase main armature winding 22, a single-phase auxiliary armature winding 23, and a field winding 24. The field winding 24 is connected to a DC power source 25 to be excited. Main armature winding 22
are connected to welding output terminals 27 and 28 via a welding output setting device 26. Welding output setting device 26
are the diodes D ₁ ~ _{D 3} and the thyristor SCR ₁ ~
SCR ₃ , a phase control circuit 29 that controls the firing angle of the thyristors SCR ₁ to SCR ₃ , and a thyristor SCR ₁
~Output current setting device 30 that varies the firing angle of SCR ₃
It consists of. The output current setter 30 uses a variable resistor. Welding output terminals 27, 28
An arc welding load 31 is connected to. On the other hand, AC auxiliary power supply output terminals 33 and 34 are connected to the auxiliary armature winding 23 via a disconnection device 32. An AC load 35 such as lighting or a power tool is connected to the AC auxiliary power supply output terminals 33 and 34. An auxiliary power output regulating device 36 is linked to the movable element 30a of the output current setting device 30. Auxiliary power output regulation device 36
is the subtracter 37, the comparator 38, and the transistor
Q ₁ . The reference terminal of the subtracter 37 is
A DC power supply 25 is connected via voltage dividing resistors R ₁ and R ₂ for obtaining a reference voltage. A DC power supply 25 is connected to a signal input terminal of the subtracter 37 via voltage dividing resistors R ₃ and R ₄ and a potentiometer 39 . The movable element 39a of the potentiometer 39 is interlocked with the operation of the movable element 30a of the output current setting device 30. The output terminal of subtractor 37 is connected to the reference terminal of comparator 38. A current transformer 41 is connected to a signal input terminal of the comparator 38 via an A/D converter 40. The current transformer 41 is interposed on the output side of the auxiliary armature winding 23 and transmits an AC detection signal proportional to the load current supplied from the auxiliary armature winding 23 to the AC load 35 to the A/D converter 40. It is now possible to input The A/D converter 40 converts the AC detection signal of the current transformer 41 into a DC voltage signal proportional to the DC voltage signal, and supplies the signal to the comparator 38 . The A/D converter 40 and the current transformer 41 constitute the output detector. The output terminal of the comparator 38 is connected to the base of the transistor _Q1 . Transistor Q ₁
The collector of is the tripping coil 32 of the disconnection device 32.
a, and the emitter is connected to the cathode of the DC power supply 25. The other end of the tripping coil 32a is connected to the anode of the DC power supply 25. In addition, in FIG. 1, _R5 is a feedback resistor.

Next, the operation of the engine-driven welding machine having the above configuration will be explained. First, the alternator 21 is driven at a predetermined speed by an engine (not shown),
Furthermore, when the field winding 24 is excited by the DC power supply 25, an electromotive force is induced in the main armature winding 22 and the auxiliary armature winding 23. The three-phase electromotive force of the main armature winding 22 is
Diodes D ₁ to D ₃ and thyristors SCR ₁ to _{SCR 3}
At the same time, the phase control circuit 29 controls the firing angles of the thyristors SCR ₁ to _{SCR 3} based on the set value by the output current setting device 30 to output a desired value of welding current to the welding output terminal 27. , 28 to the arc welding load 31. Auxiliary armature winding 23
The single-phase AC power induced can be supplied to the AC load 35 via the AC auxiliary power supply output terminals 33 and 34. A reference voltage having a value corresponding to the rated output of the engine obtained by dividing the voltage of the DC power supply 25 by the voltage dividing resistors R ₁ and R ₂ is applied to the reference terminal of the subtracter 37 . On the other hand, a DC voltage corresponding to the position of the movable element 39a is applied from the potentiometer 39 to the signal input terminal of the subtracter 37. In other words, since the movable element 39a of the potentiometer 39 is linked with the movable element 30a of the output current setting device 30, the DC voltage of the value corresponding to the welding current value set by the output current setting device 30 is calculated by the subtractor. 37 signal input terminals. Therefore, subtractor 3
7 subtracts the DC voltage corresponding to the set value of the welding current from the reference voltage value corresponding to the maximum output of the engine, and supplies the subtracted value to the reference terminal of the comparator 38. The subtracted value output from the subtractor 37 corresponds to the surplus output of the engine other than inducing a welding current of the set value in the main armature winding 22. The subtracted value is input to the reference terminal of the comparator 38, and the comparator 38 compares the subtracted value A with the auxiliary armature winding 2.
3 to the value B of the output signal of the A/D converter 40 which is proportional to the value of the AC auxiliary power output supplied to the AC load 35, and when A<B, that is, when the engine becomes overloaded. In this case, the comparator 38 turns on the transistor Q ₁ and energizes the tripping coil 32a, thereby operating the cutoff device 32 and cutting off the supply of AC power from the auxiliary armature winding 23 to the AC load 35. . Here, when the value of the welding current is changed by the output current setting device 30, the movable element 39a of the potentiometer 39 also moves in conjunction with this, so that the signal input terminal of the subtractor 37
In order to obtain a welding current of a value set in the main armature winding 22 at all times, a variable DC voltage corresponding to the surplus output other than that induced is applied, and is subtracted from a constant reference voltage proportional to the maximum output of the engine. will be done. Therefore, the comparator 38 always compares the surplus output of the engine with the engine output required to obtain the AC power supplied to the AC load 35 from the auxiliary armature winding 23. It controls transistor _Q1 .

As shown by the broken line in FIG. 1, a detector 42 for detecting the presence or absence of welding current is provided between the main armature winding 22 and the welding output terminals 27 and 28, and a voltage dividing resistor R ₃ and An on-off switch SW ₁ is inserted between the DC power source 25 and when the welding work is in a paused state, the on-off switch SW ₁ is activated by the detector 42.
is opened, and the signal input to the signal input terminal of the subtracter 37 is made zero, thereby causing Peo as shown in FIG.
It may be possible to switch to a state corresponding to , and to use up to the maximum output P ₄ that can be extracted as an AC auxiliary power source.

"Effect of the invention" As described above, according to the engine-driven welding machine according to the invention, the usable AC auxiliary power output is determined and automatically regulated from the welding output that varies according to the welding conditions, and the AC When the power supplied to the load exceeds the regulation value, the power supply to the AC load can be cut off to prevent problems caused by overloading the engine, and the engine output can be used effectively without wasting it. can.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram of an engine-driven welding machine according to the present invention, FIG. 2 is an electric circuit diagram of a conventional engine-driven welding machine, and FIG. 3 is an electric circuit diagram of a conventional engine-driven welding machine.
FIG. 6 is a diagram showing the correlation between the usable range of the AC auxiliary power supply output and the welding power supply output. 21... Alternator, 22... Main armature winding,
23...Auxiliary armature winding, 24...Field winding, 2
5...DC power supply, 26...Welding output setting device, 3
0... Output current setting device, 31... Arc welding load, 32... Breaking device, 35... AC load, 36
...Auxiliary power output regulating device, 37...Subtractor, 3
8... Comparator, 39... Potentiometer, 4
1...Current transformer.

Claims (1)

[Scope of utility model registration request] It has a generator driven by an engine and equipped with a main armature winding for a welding power source and an auxiliary armature winding for an AC auxiliary power source, and on the output side of the main armature winding of the generator. In an engine-driven welding machine equipped with a welding output setting device and a cutoff device on the output side of the auxiliary armature winding, an output detector is interposed on the output side of the auxiliary armature winding, and the welding output setting device as described above for,
Auxiliary power output for generating a variable regulation signal whose value changes in response to the output setting value, comparing the value of the variable regulation signal with the detection signal of the output detector, and controlling the above-mentioned cutoff device. An engine-driven welding machine characterized by having a regulating device interposed therein.