JPH09149697A - Internal combustion engine driven welding machine - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: To obtain a high no-load voltage and to improve the firing property of a welding arc even when the magnitude of a field current applied from an excitation generator to a main generator changes. An internal combustion engine driven welding machine is provided. SOLUTION: An output voltage of an armature coil 3 of a main generator A is applied to a welding load W through a rectifier 18. Further, the welding load driving power generation coil 7 is provided in the excitation power generator B, and the output voltage of the power generation coil 7 is applied to the welding load W through the rectifier 24. The no-load voltage obtained at the output side of the rectifier 18 by the armature coil 3 of the main generator A when the magnitude of the field current of the main generator A is set to the maximum value, The number of turns of the welding load driving generator coil 7 is selected so that the no-load voltage obtained at the output side of the rectifier 24 by the welding load driving generator coil 7 becomes higher.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine driven welding machine for supplying electric power to a welding load or the like by using a separately excited AC generator driven by an internal combustion engine.

[0002]

2. Description of the Related Art A welding machine of this type includes a main generator driven by an internal combustion engine to output a voltage for driving a welding load, an excitation generator for exciting the main generator, and an excitation generator. And a controller for controlling the field current supplied to the main generator. The main generator is composed of a separately excited AC generator having a field coil provided on the rotor and an armature coil provided on the stator, and induces a voltage for driving a welding load on the armature coil. . The excitation generator is driven by the internal combustion engine and supplies a field current to the field coil of the main generator. Further, the controller controls the field current supplied from the exciting generator to the field coil of the main generator so as to adjust the welding load current supplied from the armature coil of the main generator to the welding load.

When performing welding using this type of welding machine,
Especially when using a small diameter welding rod, it is desirable to increase the no-load output voltage of the welding machine in order to facilitate firing, and in order to stabilize the operating point when driving the welding load, It is preferable to keep the field current of the main generator at a set constant value.

Therefore, when the load current of the main generator is less than the reference value, the maximum output current of the exciting generator is supplied to the field coil of the main generator to maximize the no-load output voltage of the main generator. When the load current of the generator is equal to or higher than the reference value, the generator for supplying a constant field current set in the field coil of the main generator from the exciting generator (Japanese Patent Application No. 4-1).
No. 06779) has been proposed.

FIG. 7 schematically shows the structure of the main part of the above proposed power generator. This power generator has a field coil 1 on the rotor side and U to W3 on the stator side. Phase winding 3u
, 3v and 3w and a main generator A having an armature coil 3 consisting of a winding 3u1 connected in series with a U-phase winding 3u
′ And the main exciter armature coil 50 on the rotor side,
A main exciter B1 'having a field coil 52 for the main exciter on the stator side and driven by a rotary shaft common to the main generator A'.
A sub-exciter B2 'which is driven by a rotary shaft common to the main generator A'and the main exciter B1' and outputs an AC voltage to the stator side sub-exciter armature coil 9; Rectifier 54 for rectifying the AC voltage induced in the armature coil for use 50 to supply the field current to the field coil 1 of the main generator, and the sub-excitation when the load current of the main generator A'is less than the reference value. Machine B2
The maximum output current of the main exciter is supplied as an exciting current to the main exciter field coil 52, and when the load current of the main generator A'is equal to or greater than the reference value, the sub exciter B2 'to the main exciter field coil 5 is supplied.
An excitation controller C'for controlling the exciting current supplied from the auxiliary exciter B2 'to the field coil 52 for the main exciter so as to supply a constant exciting current set to 2. In this power generator, the three-phase AC output voltage obtained from the windings 3u to 3w of the windings forming the armature coil 3 of the main generator A'is applied to the welding load W through the rectifier 18.
Output terminals are drawn out from both ends of the series circuit of the windings 3u1, 3u and 3v, and an AC voltage obtained from these windings is supplied to the AC load L.

The excitation controller C'comprises a rectifier circuit 55 for rectifying the AC output voltage of the sub-exciter armature coil 9 and the main exciter field coil 5 by the DC output voltage of the rectifier circuit 55.
Switch circuit 5 for turning on and off the exciting current supplied to
6, an exciting current control circuit 64 for turning on / off the switch circuit 56 so as to keep the exciting current at a set value, and a load for detecting a load current flowing in the welding load W by the current transformer CT and outputting a load current detection signal. The current detection circuit 61 and the load current detection signal are compared with the reference signal that gives the reference value, and when the magnitude of the load current detection signal is less than the magnitude of the reference signal, the excitation current control circuit 64 switches the switch circuit 56. Of the auxiliary exciter machine B2 'is passed to the field coil 52 for the main exciter machine by blocking the ON / OFF control of the main exciter machine B2' by keeping the switch circuit 56 in the conductive state, and the magnitude of the load current signal is equal to that of the reference signal. When the value is equal to or larger than the magnitude, the exciting current control circuit 64 controls the on / off of the switch circuit 56 to set the exciting current of the field coil 52 for the main exciter to a set constant value. And a control switching circuit 63 for holding.

FIG. 8 shows the static characteristics of the welding output of the power generator shown in FIG. In the state where the maximum exciting current Ifo is supplied to the main exciter B1 'by the total output current of the sub exciter B2', the field current of the main generator A'becomes the maximum, so that the main generator A ' The welding load voltage Ew vs. welding load current Iw characteristic has the maximum static characteristic as shown by the curve Wo in FIG. 8, and the maximum no-load voltage Ewo can be obtained when there is no load.

When the welding load current is the reference value Iwo or more, the magnitude of the exciting current If of the main exciter B1 'can be set to a desired value smaller than the maximum exciting current Ifo.
As shown in FIG. 8, the exciting currents If, If1, If2,
If If3 (Ifo>If1>If2> If3) is set, the static characteristics of the welding output of the main generator A'are the curves W1 and W, respectively.
2, W3. When the welding load is driven, the operating point is the intersection of the static characteristic curve and the load line Rw of the welding load, and the operating points are a1, a2, and a2 depending on the set value of the exciting current If, as shown in FIG. It becomes like a3.

In the conventional power generator shown in FIG. 7, the main generator A'has windings (3u1, 3u, and 3v) for driving the AC load L. The static characteristics of the output also change according to the magnitude of the exciting current If of the main exciter B1 '. Fig. 9 shows AC load voltage VL and AC load current IL
Is a static characteristic showing the relationship with
o is a static characteristic when the welding load current is less than the reference value Iwo and the maximum exciting current Ifo is flowing in the main exciter B1 '. The curves L1, L2 and L shown by the solid lines in FIG.
Reference numeral 3 denotes the exciting currents If of the main exciter B1 ', If1 and I, respectively.
These are static characteristics when f2 and If3 (Ifo>If1>If2> If3) are set. Static characteristic curves Lo, L1, L2 and L3
At the intersections bo, b1, b2, and b3 of the load line RL of the AC load L with exciting currents Ifo, If1, If2, and If3, respectively.
It becomes the operating point of the AC load.

Further, in the welding generator shown in Japanese Patent Laid-Open No. 63-178748, the first welding winding and the second welding winding are provided on the stator of the rotating field welding generator. Then, the first and second welding windings are respectively connected via a rectifier so that the outputs of these welding windings are added with the same polarity and supplied to the load.

In this welding generator, the peak value of the no-load voltage of the second welding winding is higher than the peak value of the no-load voltage of the first welding winding. It is said that it is possible to obtain a welding output that enables the use of the welding rod of 1) and to improve the welding characteristics.

[0012]

[Patent Document 1] Japanese Patent Application No. 4-10677
In the conventional welding power generator proposed in No. 9, the maximum output current is supplied to the main exciter B1 'by the total output current of the sub exciter B2' when no load is applied to the main generator A'for welding. By making it possible to obtain the maximum no-load voltage Ewo, it is possible to improve the firing property of the welding arc.

However, this generator has a problem that the AC load voltage rises sharply when the welding load is unloaded while both the welding load and the AC load are being driven. For example, in FIGS. 8 and 9, when the exciting current of the main exciter is If1 and the welding load and the AC load are operating at operating points a1 and b1, respectively, Operating points are from b1 to b
A sudden change to o causes the AC load voltage to rise rapidly from VL1 to VLo. Therefore, the voltage applied to the AC load may become excessive and the AC load may be burned.

Further, in the welding generator disclosed in Japanese Patent Laid-Open No. 63-178749, since the first welding winding and the second welding winding are wound on the same stator, the excitation is performed. When the magnitude of the current is set small, there is a problem that the no-load voltage of the second welding winding also becomes small and the firing property deteriorates.

An object of the present invention is to apply a substantially constant high no-load voltage to the welding load even when the magnitude of the field current supplied from the excitation generator to the field coil of the main generator changes. It is an object of the present invention to provide an internal combustion engine drive welding machine capable of achieving excellent firing characteristics.

Another object of the present invention is, when the output terminal for driving the AC load is drawn from the armature coil of the main generator, even if the welding load is in an unloaded state, an excessive voltage is applied to the AC load. It is an object of the present invention to provide an internal combustion engine driven welding machine in which no heat is added.

[0017]

SUMMARY OF THE INVENTION The present invention includes a main generator having a field coil and an armature coil, which is driven by an internal combustion engine to induce a welding load driving voltage in the armature coil; An excitation generator that is driven by an engine to supply a field current to the field coil of the main generator, and a controller that controls the field current supplied from the excitation generator to the field coil of the main generator. And a welding machine driven by an internal combustion engine.

In the present invention, the output voltage of the armature coil of the main generator is applied between the output terminals to which the welding load is connected through the first rectifier. Further, a welding load driving power generation coil is provided in the excitation power generator, and the output voltage of the welding load driving power generation coil is applied between the output terminals through the second rectifier. Then, rather than the no-load voltage obtained at the output side of the first rectifier by the armature coil of the main generator when the magnitude of the field current of the main generator is set to the maximum value,
The number of turns of the welding load driving generator coil is selected so that the no-load voltage obtained at the output side of the second rectifier by the welding load driving generator coil of the excitation generator is higher.

With the above-mentioned structure, even if the field current of the main generator changes, a welding load driving generator coil of the exciting generator is provided between the output terminals to which the welding load is connected. Since a constant high no-load voltage is always obtained,
Even if the set value of the field current of the main generator is changed according to the welding load, the welding arc can always be fired well.

Also, with the above construction, since the field current of the main generator is not supplied to the field coil of the main generator when the welding load is zero, the armature of the main generator is not supplied. Even if the welding load changes from the load state to the no-load state when the output terminal for driving the AC load is pulled out from the coil, there is no fear that an excessive voltage is applied to the AC load.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. In the figure, A is a main generator consisting of a separately excited alternating current generator, B is an exciting generator consisting of a main exciter B1 and a sub-exciter B2, and C is a main exciter by controlling the exciting current of the main exciter B1. A controller that controls the field current of the generator,
18 is a first rectifier, 24 is a second rectifier, 11 and 5
Reference numeral 4 is a three-phase reactor circuit and three-phase full-wave rectifier, L is an AC load, and W is a welding load.

The main generator A is connected in series with a rotor 2 having a field coil 1, windings 3u, 3v and 3w of U to W3 phases and a winding 3u of U phase which are Y-connected. And a stator 4 having an armature coil 3 composed of a winding 3u1.

The main exciter machine B1 comprises a rotor 51 having a main exciter machine armature coil 50 connected in three-phase Y and a stator 53 having a main exciter machine field coil 52.
As shown in, the rotor 51 is attached to the rotary shaft S common to the rotor 2 of the main generator A, and is driven by the internal combustion engine E.

The sub-exciter B2 has a multi-pole magnet rotor 8 and
It consists of a magnet type AC generator provided with an armature coil 9 for a sub-exciter and a stator 10 having a generator coil 7 for driving a welding load, and the magnet rotor 8 has an internal combustion engine as shown in FIG. It is driven by E and rotates synchronously with the rotor 2 of the main generator A and the rotor 51 of the main exciter B1.

The output of the armature coil 50 for the main exciter is supplied to the field coil 1 of the main generator through a three-phase full-wave rectifier 54 composed of diodes D1 to D6. Rectifier 5
4 is attached to the rotating shaft S.

Windings 3u-3 of the armature coil 3 of the main generator
The three-phase AC output obtained from w is the reactor 11u to 1u.
The output voltage of the first rectifier 18 is input to the first rectifier 18 which is a three-phase bridge connection of the diodes 12 to 17 through 1w, and the output voltage of the first rectifier 18 is connected to the welding load W consisting of the welding electrode and the base metal 19a. , 19b. Further, among the windings constituting the armature coil 3, the windings 3u1, 3u and 3v are used as the AC load driving generator coils, and the AC load driving output drawn from both ends of the series circuit of these windings. A single-phase AC load L is connected between the terminals.

The single-phase AC output obtained from the welding load driving generator coil 7 of the sub-exciter B2 is input to the second rectifier 24 consisting of the single-phase bridge connection of the diodes 20 to 23, and the second rectifier's The output voltage is output terminal 19a,
19b, which is applied to the welding load driving generator coil 7
The output of the three-phase winding 3u ~ 3w of the armature coil of the main generator
Is supplied to the welding load W by being superimposed on the output of

The controller C is provided with a rectifying circuit 55 composed of the diodes D7 to D10, and the armature coil 9 for the auxiliary exciter machine.
Is output to the rectifier circuit 55. Rectifier circuit 55
The positive-side output terminal of is connected to one end of the main exciter field coil 52, and the other end of the field coil is connected to the collector of an NPN transistor Tr1 whose emitter is grounded.
A resistor R1 and a diode D11 are connected between the collector base and the collector emitter of the transistor Tr1, respectively, and a diode D12 is connected across the field coil 52 for the main exciter machine. The transistor Tr1, the resistor R1, and the diodes D11 and D12 form a switch circuit 56 for turning on / off the exciting current supplied from the sub exciter B2 to the field coil 52 of the main exciter B1 through the rectifier circuit 55.

A smoothing capacitor C1 is connected between the output terminals of the rectifier circuit 55, and a resistor R is provided across the capacitor C1.
Zener diode ZD is connected through 2.
A constant voltage power supply circuit 57 is constituted by the capacitor C1, the resistor R2 and the Zener diode ZD, and a DC constant voltage is obtained across the Zener diode ZD.

The output voltage of the constant voltage power supply circuit 57 is applied to a known triangular wave signal generating circuit 58 which generates a triangular wave signal Vs having a constant frequency, and the triangular wave signal Vs (FIG. 3A) is input to the non-inverting input terminal of the comparator CP1. It has been entered. Comparator C
The setting signal Vr obtained by dividing the output voltage of the constant voltage power supply circuit 57 by the resistor R3 and the variable resistor RV1 is input to the inverting input terminal of P1. The set signal Vr gives a set value of the exciting current supplied to the field coil 52 of the main exciter B1 (set value of the field current of the main generator A). As shown in FIG. 3B, during the period in which the magnitude of the triangular wave signal Vs is equal to or higher than the level of the setting signal Vr, the first level state (high level state in this example) is set, and the triangular wave signal Vs The rectangular wave signal Vq which is in the second level state (zero level state in this example) during the period when the magnitude is less than the magnitude of the setting signal Vr.
Is obtained. The time width of the portion of the rectangular wave signal Vq in the first level state changes according to the magnitude of the setting signal Vr. For example, when Vr is Vr1 and Vr2 (<Vr1), the waveforms of the rectangular wave signal Vq are as shown in the left and right halves of FIG. 3B, respectively. When the magnitude of the setting signal Vr is reduced, The time width of the portion of the rectangular wave signal Vq in the first level state becomes wider. In this example, the comparator C
A rectangular wave signal generation circuit 59 is constituted by P1, the resistor R3 and the variable resistor VR1.

Between the base and emitter of the transistor Tr1 of the switch circuit 56, the collector-emitter circuit of the NPN transistor Tr2 whose emitter is grounded is connected in parallel.
A resistor R4 is connected between the base and emitter of the transistor Tr2. The base of the transistor Tr2 is coupled to the output terminal of the comparator CP1 through the resistor R5,
The rectangular wave signal Vq obtained at the output terminal of No. 1 is applied to the base of the transistor Tr2 through the resistor R5. The transistor Tr2 is turned on when the rectangular wave signal Vq is at the first level (high level in this embodiment) to turn off the transistor Tr1 of the switch circuit 56, and the rectangular wave signal Vq is at the second level ( In the present embodiment, the transistor Tr1 of the switch circuit 56 is turned on when the transistor Tr1 of the switch circuit 56 is in the cutoff state. In this example, the transistor Tr2 and the resistors R4 and R5 form a cutoff control switch 60. Excitation using the triangular wave signal generation circuit 58, the rectangular wave signal generation circuit 59, and the cut-off control switch 60 to turn the switch circuit 56 on and off so as to keep the exciting current flowing in the field coil 52 of the main exciter B1 at a set value. A current control circuit is configured.

Next, the operation of the welding machine shown in FIG. 1 will be described. The transistor Tr2 of the cutoff control switch 60 is conductive while the rectangular wave signal Vq is at a high level, and is in the cutoff state while the rectangular wave signal Vq is at a zero level, so that the collector potential Vc2 of the transistor Tr2 is not changed. Figure 3 (C)
It becomes as shown in. Since the transistor Tr1 of the switch circuit 56 is in the cut-off state while the transistor Tr2 is conductive and the transistor Tr1 is in the conductive state during the cut-off of the transistor Tr2, the collector potential V of the transistor Tr1 is V.
c1 changes as shown in FIG. An exciting current is supplied from the auxiliary exciter B2 to the field coil 52 of the main exciter B1 during the period Ti during which the rectangular wave voltage Vc1 in FIG. 3D is zero. When the magnitude of the setting signal Vr is large, the energizing time Ti of the exciting current is long, and when the magnitude of the setting signal Vr is small, the energizing time Ti of the exciting current is short. Therefore, the average value If of the exciting current increases or decreases substantially in proportion to the magnitude of the setting signal Vr, and the exciting current is held at the constant value set by the setting signal Vr. The set value of the exciting current If can be adjusted by the variable resistor VR1.

The exciting current If of the main exciter B1 is amplified by the main exciter, and the field coil 1 of the main generator A is excited by the main exciter by the current output from the armature coil 50 for the main exciter. An exciting current is supplied which is increased substantially in proportion to the current If.

FIG. 4 shows that when the exciting current If of the main exciter machine B1 is kept constant at a set value, and therefore the field current of the main generator A is also kept constant, the output terminals 19a, 19 are turned on.
3 shows the voltage-current static characteristic of the output obtained between points b. The static characteristics of the output obtained only by the main generator A when the exciting current If of the main exciter B1 is If1 (maximum set value), If2 and If3, respectively, are the curves W1 'and W2 indicated by broken lines in the figure. 'And W3', and the no-load voltages are Eo1, Eo2, and Eo3, respectively. On the other hand, the static characteristic of the output obtained between the output terminals 19a and 19b by the welding load driving generator coil 7 provided in the sub-exciter B2 is
The curve We is shown in FIG. 4 regardless of the magnitude of the exciting current If of the main exciter, and the no-load voltage is Eoe.

The output voltage vs. current static characteristic of the output obtained by superimposing the output of the welding load driving magneto coil 7 of the sub exciter B2 on the output of the armature coil 3 of the main generator A is shown by the curve We in FIG. Each of the curves W1 ', W2' and W3 'is represented by a curve obtained by adding the output currents of the two with respect to the same output voltage, and the exciting current If of the main exciter B1 is represented by If1, If2 and If3. The voltage-current static characteristics at this time are shown by the solid curves W1, W2 and W in FIG. 4, respectively.
3 and the solid part of the curve We. The operating points when the welding load W is being driven are the intersections a1, a2 and a3 of the curves W1, W2 and W3 and the load line Rw of the welding load W.

In the present invention, the magnitude of the no-load voltage Eoe obtained at the output side of the second rectifier 24 by the output of the welding load driving generator coil 7 provided in the sub exciter B2 is the main exciter B1. Excitation current If is set to maximum value If1
Of the welding load drive generator coil 7 such that the output of the armature coil 3 of the main generator A becomes higher than the no-load voltage Eo1 obtained at the output side of the first rectifier 18 when set to 1. Select the number of turns. By selecting the number of turns of the welding load driving generator coil 7 as described above, even if the set value of the magnitude of the exciting current If of the main exciter machine B1 is changed, a sufficiently high value can be obtained between the output terminals 19a and 19b. Since the load voltage can be obtained, the welding arc can always be fired well.

Of the windings forming the armature coil 3 of the main generator A, the voltage-current static characteristic of the single-phase AC output obtained from the AC load driving coil composed of the windings 3v, 3u and 3u1 is as follows. As shown in FIG. 5, the exciting current If of the main exciter machine B1
Curves L1 for the set values If1, If2 and If3 of
, L2 and L3. The operating points when the AC load L is driven are the intersections b1, b2 and b3 of the curves L1, L2 and L3 and the load line RL of the AC load L, and the load voltages at this time are VL1 and V, respectively.
It becomes L2 and VL3. Even if the welding load W is unloaded while both the welding load W and the AC load L are being driven, the exciting current If of the main exciter machine B1 is kept constant unless the set value is changed. Therefore, the magnitude of the load voltage VL of the AC load L is only affected by the decrease in the voltage drop across the windings 3u and 3v, and the voltage applied to the AC load L does not rise significantly.

In the above example, the exciting generator B is constituted by the main exciter B1 consisting of the separately excited alternating current generator and the sub exciter B2 consisting of the magnet type generator, and the main exciter B2 is driven by the output of the sub exciter B2. The controller C controls the exciting current supplied to the field coil 52 of the exciter B1 and the main generator A to which the exciting current is supplied by the output of the main exciter B1 is a non-brush type separately excited type. Although an AC generator is used, if the required field current can be directly supplied to the main generator A through the controller with the output of the excitation generator composed of a magnet type AC generator,
As shown in FIG. 6, a separately excited AC generator having a brush and a slip ring may be used as the main generator A, and the exciting generator B may be configured by only a magnet type AC generator.

In FIG. 6, the field coil 1 of the main generator A
Both terminals are connected to slip rings 5a and 5b, and brushes 6a and 6b are in contact with these slip rings. The controller C has the same configuration as the controller used in the embodiment shown in FIG. Both ends of the armature coil 9 of the excitation generator B composed of a magnet type AC generator are connected to the AC input terminals of the rectifier circuit (rectifier circuit 55 in FIG. 1) provided in the controller C, and The positive output terminal and the collector of the transistor Tr1 (see FIG. 1) of the switch circuit 56 are connected to the brushes 6a and 6b of the main generator A, respectively. Other parts are the same as in the embodiment of FIG. In this embodiment, the field current flowing through the field coil 1 of the main generator A is held at the set value by the controller C.

[0040]

As described above, according to the present invention, the welding load driving power generation coil is provided in the excitation power generator, and the output of the welding load driving power generation coil is output from the armature coil of the main power generator. Since it is superposed on and supplied to the welding load,
When attempting to fire the welding load, it is possible to apply an almost constant high no-load voltage obtained from the welding load driving magneto coil to the welding load, regardless of the setting value of the field current of the main generator. it can. Therefore, regardless of the diameter of the welding rod used, it is possible to always perform good firing.

Further, according to the present invention, when the welding load is suddenly brought to a no-load state while the welding load and the AC load are both driven, the field current of the main generator increases and the AC load increases. Since it is possible to prevent the voltage from rapidly increasing, it is possible to eliminate the risk of the AC load being burned by an excessive voltage.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration example of a welding machine according to the present invention.

FIG. 2 is a configuration diagram schematically showing a mechanical configuration of a main part of the welding machine of FIG.

3 is a waveform diagram showing voltage waveforms at various parts of the controller used in the example shown in FIG.

FIG. 4 is a diagram showing an example of welding load voltage-welding load current characteristics and exciting current-welding load current characteristics obtained by the welding machine of the present invention.

FIG. 5 is a diagram showing an example of AC load voltage-AC load current characteristics and exciting current-AC load current characteristics obtained by the welding machine of the present invention.

FIG. 6 is a circuit diagram showing another configuration example of the welding machine of the present invention by using a partial block diagram.

FIG. 7 is a circuit diagram showing the configuration of a conventional power generator for an internal combustion engine drive welding machine by using a partial block diagram.

8 is a diagram showing welding load voltage-welding load current characteristics and exciting current-welding load current characteristics obtained by the conventional example of FIG.

9 is a diagram showing an AC load voltage-AC load current characteristic and an exciting current-AC load current characteristic obtained by the conventional example of FIG.

[Explanation of symbols]

 A main generator B generator for excitation B1 main exciter B2 auxiliary exciter C controller 1 field coil 2 rotor 3 armature coil 4 stator 7 welding load drive generator coil 8 magnet rotor 9 for auxiliary exciter Armature coil 10 Stator for auxiliary excitation 18 First rectifier 19a, 19b Output terminal 24 Second rectifier 50 Main exciter armature coil 51 Main exciter rotor 52 Main exciter field coil 53 Main exciter Machine stator 54 Three-phase full-wave rectifier 55 Rectifier circuit 56 Switch circuit 57 Constant voltage power supply circuit 58 Triangular wave signal generation circuit 59 Rectangular wave signal generation circuit 60 Cut-off control switch

Claims (2)

[Claims] 1. A separately-excited main generator that has a field coil and an armature coil and is driven by an internal combustion engine to induce a voltage for driving a welding load in the armature coil, and is driven by the internal combustion engine. An excitation generator that supplies a field current to the field coil of the main generator, and a controller that controls the field current supplied from the excitation generator to the field coil of the main generator. In an internal combustion engine-driven welding machine provided with the welding machine, the output voltage of the armature coil of the main generator is applied between the output terminals to which a welding load is connected through the first rectifier, and the welding load driving power generation is performed in the exciting generator. A coil is provided, and the output voltage of the welding load driving power generation coil is the second
The rectifier applied by the armature coil of the main generator when the magnitude of the field current applied to the field coil of the main generator is set to the maximum value. Driving the welding load so that the no-load voltage obtained at the output side of the second rectifier by the welding load driving generator coil of the excitation generator is higher than the no-load voltage obtained at the output side of A welding machine driven by an internal combustion engine, characterized in that the number of windings of the power generating coil for use is selected. 2. The internal combustion engine drive welding machine according to claim 1, wherein an output terminal for applying a voltage to an AC load is further drawn from an armature coil of the main generator.