JP6982503B2 - Engine drive work machine - Google Patents

Description

The present invention relates to an engine-driven working machine that outputs electric power generated by a power generator driven by an engine.

Generally, in arc air gouging (hereinafter, simply referred to as gouging), an arc is generated between a carbon electrode mounted on a gouging torch and an iron plate to melt metal, and at the same time, a compressor for air supply (hereinafter referred to as air supply compressor). , Simply referred to as an air compressor), injects compressed air parallel to the electrodes. As a result, the molten metal can be blown off, and the iron plate can be chipped, drilled, and cut.

Patent Document 1 discloses a welding power supply device to which a semi-automatic welding module and a gouging working device for performing arc air gouging (hereinafter, simply referred to as gouging) can be replaced and connected.

Further, Patent Document 2 discloses an engine-driven welding machine configured to be capable of supplying a DC power supply and an AC power supply.

Japanese Unexamined Patent Publication No. 2016-159329 Japanese Unexamined Patent Publication No. 2009-18343

However, in the technique of Patent Document 1, it is necessary to separately provide a power supply device for gouging (DC power supply device for welding) and a power supply device for a compressor (AC power supply device), which is not convenient for workers. It was a thing.

Patent Document 2 is configured to be able to supply a DC power supply and an AC power supply, but the power consumption due to the load on the DC power supply side (for example, gouging) and the power consumption due to the load on the AC power supply side (for example, compressor) are different. If the total output power exceeds a predetermined value and becomes an overload state, the engine rotation speed may decrease and the output voltage of the AC power supply may decrease. Then, it may affect the load connected to the AC power supply side. For example, when the motor of the compressor on the AC power supply side is connected, the motor cannot be started, and an overcurrent may flow through the motor, causing burnout.

Therefore, an object of the present invention is to provide an engine drive working machine configured to avoid a decrease in AC output even when a DC power supply and an AC power supply are used at the same time.

The engine drive working machine according to the first aspect of the present invention includes an engine, a power generator driven by the engine to generate AC power, and an AC output terminal for outputting the AC power generated from the power generator. To output the first current measuring means for measuring the AC output current output from the AC output terminal, the rectifier for converting the AC power generated from the generator into DC power, and the DC power rectified by the rectifier. The DC output terminal, the second current measuring means for measuring the DC output current output from the DC output terminal, and the DC output current are reduced when the AC output current exceeds a predetermined first threshold value. As described above, it is characterized by including an output control unit that controls the rectifier.

According to this aspect, the output control unit controls the rectifier so as to reduce the DC output current output from the DC output terminal when the AC output current output from the AC output terminal exceeds a predetermined first threshold value. is doing. As a result, it is possible to prevent the engine from becoming overloaded and the number of revolutions decreasing. It is conceivable that the AC output decreases when the engine speed decreases, but according to the configuration of this embodiment, the engine speed decrease can be avoided, so that the output from the AC output terminal can be avoided. As a result, stable operation of the device connected to the AC output terminal can be ensured. For example, when a motor is connected to an AC output terminal, the motor can be stably started while supplying DC power.

Specifically, the engine drive work machine according to this embodiment is configured to be able to output both DC power and AC power. Therefore, for example, a gouging work device (gouging torch, carbon electrode and iron plate) is attached to the DC output terminal. An air compressor (including an air tank, motor, and pump) can be connected to the AC output terminal. That is, one engine-driven work machine can supply compressed air from the air compressor to the gouging torch while operating the gouging work device. In this case, the motor is automatically started when the air tank of the air compressor runs out of compressed air, but the starting current of the motor is several times the normal operating current. If the gouging work is performed with high efficiency at the time of starting the motor, a large current is required even in the gouging work device, so that a heavy load is applied to the engine. As a result, if the engine speed drops, the AC output drops and the motor cannot start, overcurrent flows through the motor, causing motor burnout, and at the same time, the gouging output drops and gouging work becomes impossible. .. According to the configuration of this aspect, there is no such thing. That is, since it is possible to avoid a decrease in the engine speed, it is possible to avoid a decrease in the output from the AC output terminal, and the motor of the air compressor can be started easily and stably. Further, in this embodiment, even if the AC output current exceeds a predetermined first threshold value, the DC output current is not stopped, so that the gouging work can be continued. That is, according to the configuration of this aspect, the motor can be started easily and stably even during the gouging work while minimizing the decrease in the efficiency of the gouging work.

The output control unit restores the DC output current when the AC output current becomes less than the second threshold value smaller than the first threshold value after the first output current exceeds the first threshold value. The rectifier may be controlled so as to cause the rectifier.

In this way, when a difference is provided between the first threshold value for reducing the output of the rectifier and the second threshold value for restoring the output of the rectifier, the output characteristics change in the vicinity of the threshold value ( Also in the application), the engine drive work machine can be operated stably.

Further, the output control unit may control the rectifier so that the DC output current is restored after a predetermined time has elapsed after the AC output current exceeds the first threshold value.

Some devices connected to the AC output terminal have a fixed time that requires a large current. Therefore, by reducing the DC output current and then recovering it after a predetermined time has elapsed, it is possible to avoid the engine becoming overloaded and the rotation speed decreasing.

The output control unit may adjust the decrease amount of the DC output current according to the increase amount of the AC output current. Further, the output control unit may adjust the decrease amount of the DC output current so that the difference between the decrease amount of the DC output current and the increase amount of the AC output current becomes small. Further, the first threshold value is composed of a plurality of first threshold values whose values increase discretely, and the output control unit applies the DC output current as the AC output current exceeds each of the first threshold values. The rectifier may be controlled to gradually decrease.

According to these configurations, the amount of decrease in the DC output current is set according to the amount of increase in the AC output current, so that the output of the engine drive working machine can be utilized more efficiently. That is, it is possible to take out a larger output from the engine-driven work machine while allowing the engine-driven work machine to operate stably.

The second output terminal is an output terminal for connecting a gouging work device.

Since the gouging work apparatus requires a very large current and the work can be continued even if the current decreases during the work, the engine drive work machine according to this embodiment can be suitably applied.

The engine drive working machine according to the present invention can avoid a decrease in the output of the AC output terminal even when the DC power supply and the AC power supply are used at the same time.

Schematic configuration diagram of an engine drive working machine (engine welding machine) according to an embodiment The figure which shows the AC output current waveform and DC output current waveform at the time of motor start-up. The figure which shows the change of AC output and DC output at the time of motor start. The figure which shows other example of the AC output current waveform and DC output current waveform at the time of motor start-up. The figure which shows the other example of the change of AC output and DC output at the time of motor start. In the comparative example, the figure which shows the AC output current waveform and the DC output current waveform at the time of starting a motor. The figure which shows other example of the AC output current waveform and DC output current waveform at the time of motor start-up. The figure which shows the other example of the change of AC output and DC output at the time of motor start.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description of preferred embodiments is merely exemplary and is not intended to limit the invention, its applications or its uses.

The engine-driven work machine according to the present embodiment has a power generator driven by an engine, has a function of outputting AC power generated by the power generator, and outputs DC power obtained by rectifying the AC power generated by the power generator. It has a function to output from the terminal. That is, it is an engine drive working machine equipped with a DC power supply and an AC power supply. The engine drive working machine is characterized by output control according to the output current output from the output terminal.

Generally, the protection function of a generator, an engine drive work machine, or the like is intended to protect circuits, elements, or the like in the own machine. That is, in the conventional engine drive work machine (generator), for example, when an overload or an overcurrent is detected, the output is stopped or the output is output in order to prevent damage to the circuits and elements in the own machine. It is configured to squeeze. On the other hand, the engine drive working machine according to the present embodiment is characterized in that it can protect a device connected to an AC power supply terminal (particularly, a device equipped with a motor).

In the following description, as an example of the engine drive working machine according to the present disclosure, an engine configured to be able to select and supply a welding power source (hereinafter referred to as a welding power source) and a gouging power source (hereinafter referred to as a gouging power source). A type welding machine (hereinafter referred to as an engine welding machine) will be described. Although the details will be described later, a particularly remarkable effect can be expected by applying the technique according to the present invention to the engine welder. However, the scope of application of the present invention is not limited to the engine welding machine, and can be widely applied to the engine drive working machine equipped with the DC power supply and the AC power supply.

-Structure of engine welder-
FIG. 1 is a diagram showing a schematic configuration of an engine welding machine that also serves as a generator as an engine driving working machine according to the present embodiment.

The engine welder 1 includes an AC power supply 2 (upper side of the drawing of FIG. 1) and a DC power supply 3 (lower side of the drawing of FIG. 1) that can be used as a gouging power supply. Specifically, the engine welder 1 includes an engine 11, a power generator 12 driven by the engine 11 to generate AC power, a rectifier 31 for a DC power supply 3, and a control board 4. The control board 4 has a first power calculation circuit 41 that calculates the power on the AC power supply 2 side, a second power calculation circuit 42 that calculates the power on the DC power supply 3, and an output control unit that controls the output of the rectifier 31. 43 and is installed.

Further, the engine welding machine 1 is provided with an operation unit 16 that receives an operation by the user. The operation unit 16 includes a mode changeover switch 16a and an output adjustment dial 16b. The mode changeover switch 16a is a switch for switching whether the DC power supply 3 is used as a gouging power supply or a welding power supply. The output adjustment dial 16b is a dial-type output adjustment unit for adjusting the output of the DC power supply 3.

The generator 12 has a three-phase winding that generates AC power for the AC power supply 2 (hereinafter referred to as an AC power supply winding 12a) and a three-phase winding that generates AC power for the DC power supply 3. , DC power supply winding 12b).

The AC power supply 2 is configured to output AC power generated from the AC power supply winding 12a from the AC output terminal 23 via the three-phase AC distribution line 22. The AC distribution line 22 of each phase is provided with a breaker 21 that cuts off the electric circuit of the AC distribution line 22 when an overcurrent or the like occurs.

In the AC power source 2, (corresponding to the first current measuring means) at least in part, the first ammeter CT1 for measuring an AC output current I _M that is output from the AC output terminal 23 of the AC mains 22 Is provided. Measurement results of the AC output current I _M is sent to the first power computing circuit 41 of the control board 4. Further, a wiring for voltage measurement is connected between two phases of the AC distribution line 22 (AC output terminal 23), and this wiring is connected to the first power calculation circuit 41. In the first power calculating circuit 41 measures an AC output voltage V _M which is outputted from the AC output terminal 23. Further, the first power calculating circuit 41 performs computation of the AC output power P _M from the measurement results of the AC output current I _M and the AC output voltage V _M, and outputs the operation result to the output control unit 43.

The DC power supply 3 is configured to rectify the AC power generated from the DC power supply winding 12b by the rectifier 31 and output the rectified DC power from the DC output terminal 33 via the single-phase DC distribution wire 32. ing. The configuration of the rectifier 31 is not particularly limited as long as it can convert three-phase alternating current into direct current, but it can be configured by, for example, a diode bridge circuit as shown in FIG.

In the DC power source 3, one to the DC distribution line 32 (corresponding to the second current measuring means) second ammeter CT2 for measuring the DC output current I _G to be output from the DC output terminal 33 is provided There is. Measurement results of the DC output current I _G is sent to the second power computing circuit 42 of the control board 4. Further, a wiring for voltage measurement is connected to the DC distribution line 32 (DC output terminal 33), and this wiring is connected to the second power calculation circuit 42. In the second power computing circuit 42 measures the DC output voltage V _G output from the DC output terminals 33. In the second power calculation circuit 42 performs calculation of the DC output power P _G from the measurement result of the DC output current I _G and the DC output voltage V _G, and outputs the operation result to the output control unit 43.

The control board 4 is equipped with a microcontroller (not shown) having a function of controlling the overall operation of the engine welding machine 1, and measurement circuits and calculation circuits such as power calculation circuits 41 and 42. In addition, in FIG. 1 and this embodiment, among the constituent elements mounted on the control board 4, the elements related to the present invention are illustrated and described.

The output control unit 43 has a function of controlling the output of the rectifier 31 based on the calculation results of the first power calculation circuit 41 and the second power calculation circuit 42 and the operation information from the operation unit 16. The specific operation of the output control unit 43 will be described in detail in the following “Operation of engine welder”.

-Operation of engine welder (1)-
Next, the operation and control of the engine welding machine 1 will be specifically described with reference to FIGS. 1 to 3. In the following description, as shown in FIG. 1, it is assumed that the gouging work device 8 is connected to the DC power supply 3 and the air compressor 7 for supplying compressed air is connected to the AC power supply 2.

Specifically, in the DC power supply 3, the gouging torch 81 is connected to the positive electrode of the DC output terminal 33, and the iron plate 83 to be gouged is connected to the negative electrode. A carbon electrode 82 is attached to the tip of the gouging torch 81. In the present embodiment, the equipment related to the gouging work including the gouging torch 81, the carbon electrode 82, and the iron plate 83 is collectively referred to as the gouging work device 8.

Further, the air compressor 7 connected to the AC power supply 2 includes a motor 71, an air tank 72, and a pump 73, and supplies compressed air (see the arrow at the lower right of FIG. 1) ejected from the gouging torch 81 during the gouging operation. Is for. Specifically, the motor 71 is connected to the AC output terminal 23 and drives the pump 73. The pump 73 generates compressed air and stores it in the air tank 72. The compressed air in the air tank 72 is supplied to the gouging torch 81 via the air hose 74, and is ejected from the gouging torch 81 when the gouging work is started.

It is assumed that the gouging operation is performed with sufficient compressed air stored in the air tank 72 at the time point T0 (the left end in FIG. 2), which is the starting point of the explanation. Here, during the gouging work, the air compressor 7 (motor 71) is not always in operation, and is in intermittent operation. That is, the motor 71 starts when the remaining amount of compressed air in the air tank 72 (hereinafter, simply referred to as the remaining amount of air) becomes a predetermined value or less to generate compressed air, and operates when the compressed air is sufficiently generated. Perform intermittent operation to stop. The motor 71 requires a very large starting current for a predetermined period from the time of starting, and can be operated with a smaller current than that at the time of starting in the subsequent steady operation.

In the following description, a period requiring a large current at the time of starting the motor may be referred to as a motor start period Ts, and other periods may be referred to as a steady operation period. The motor start-up period Ts is a period that depends on the capacity of the air pump 73, the capacity of the motor 71, and the like, and is not particularly limited, but is, for example, about 1 to several seconds. The steady operation period depends on the current flowing through the gouging work device 8, the capacity of the air pump 73, the injection amount of compressed air, and the like, and is not particularly limited, but is, for example, several tens of seconds to several tens of seconds. It's about a minute.

First, at time T0 of FIG. 2, the motor 71 is stopped, the AC output current I _M is not flowing, the current only from the engine welder 1 to gouging working device 8 is supplied. Specifically, the DC output terminal 33, while flowing the DC output current I _G1 corresponding to the thickness and the set value of the output adjustment dial 16b of the carbon electrodes 82, no current flows to the AC output terminal 23.

FIG. 3A shows the output state of the engine welding machine 1 at the time T0 of FIG. DC output P _G1, for example, when the voltage V _G1 is applied to gouging working device 8,
P _G1 = V _G1 x I _G1 ... (1)
Will be.

Then, at time T10 in FIG. 2, the air remaining in the air tank 72 is below a predetermined value, the motor 71 starts rotating, the AC output current I _M starts to increase. Then, at time T11, when the AC output current _{I M} exceeds a predetermined first threshold value _{I M1,} the output control unit 43, a DC output current being supplied to the gouging working device 8 from _{I G1 I} G2 _{(I G1} > The output of the rectifier 31 is controlled so as to decrease to _IG2).

3 (b) and 3 (c) show changes in the output state of the engine welder 1 before and after the time T11 in FIG. FIG. 3B shows a state immediately before the output control unit 43 controls the rectifier 31, and FIG. 3C shows a state immediately after the output control unit 43 controls the rectifier 31. In FIG. 3B, for example, assuming that the voltage _VM1 is applied to the motor 71, the AC output _PM1 is
_PM1 = _VM1 × _IM1 ... (2)
Will be.

Here, for example, the first threshold value _IM1 is set by the sum of the DC output _PG1 and the AC output _PM1 with a predetermined margin with respect _{to the electric power PD1} capable of continuous output of the engine welding machine 1. It is set based on the _{set power PD2.} Specifically, for example, the first threshold value _IM1 is set to an AC output current value that satisfies the following equation (3).

P _D2 = P _G1 + P _M1 ... (3)
Thereafter, it exceeds the first threshold value _{I M1} AC output current is predetermined, when the output control unit 43 controls the rectifier 31, the DC output current _{I G} is changed from _{I G1} to _{I G2,} as shown in FIG. 3 (c) DC output _{P G} is decreased from _{P G1} to _{P G2} to. DC output _{P G2} is, for example, when the voltage _V G2 against gouging working device 8 _(V G2 _{<V G1)} is applied,
P _G2 = V _G2 x I _G2 ... (4)
Will be. Incidentally, the amount of decrease in the DC output current _{I G} of the engine welder 1 or _(I G1 _{-I G2)} How to set, _{i.e., P G5 (P G5 = P} G1 -P G2) shown in FIG. 3 (c) Will be explained later on how to set.

From time T11 to time T12, the current consumed by the motor 71 increases. That is, the AC output current I _M of the engine welder 1 is increased. Then, at time T12, the AC output current _{I M} of the engine welder 1 is the peak current _{I M2.} At this time, the DC output current _{I G} are the same as in the _{I G2,} i.e., the DC output _{P G} remains _{P G2.}

FIG. 3D shows the output state of the engine welder 1 at the time T12 of FIG. In FIG. 3D, for example, assuming that the voltage _VM2 ( _VM2 < _VM1 ) is applied to _{the motor 71, the AC output PM2} is
_PM2 = _VM2 x _IM2 ... (5)
Will be.

Here, the above-mentioned decrease amount of DC output _PG5 is larger than the increase amount of AC output on the motor 71 side, that is, has a predetermined margin with respect to the increase amount of AC output on the motor 71 side. Is set to. For example, when the relationship as described in the above equation (3) is established, the reduction amount _PG5 of the DC output may be set so as to satisfy the following equation (6).

P _G5 ≧ P _M2- P _M1 ... (6)
More preferably, for example, since there are some recommended values as the output of the air compressor 7 used for the gouging operation, even when the air compressor 7 having the maximum output among the recommended values is connected, the above It is preferable to set the _{reduction amount PG5} so that the condition of the formula (6) is satisfied. By doing so, it is possible to support the air compressor 7 having a wide range of specifications.

After the time T12, the current consumed by the motor 71 decreases. That is, the AC output current I _M of the engine welder 1 is reduced. Then, at time T14, when the AC output current _{I M} becomes smaller than a predetermined second threshold _{I M3 (I M3 <I M1} ), the output control unit 43, the DC output current is supplied to the gouging working device 8 I the _G to return to _{I G1} from _{I G2} (back) as to control the output of the rectifier 31.

FIG. 3 (e) output control unit 43 indicates a state after the return control of the DC output current I _G against rectifier 31. In FIG. 3 (e), for example, assuming that the voltage _VM3 ( _VM2 < _VM3 ≤ _{VM4 ) is applied to the motor 71, the AC output PM3} will be the AC output PM3.
_PM3 = V _M3 x I _M3 ... (7)
Will be. _{Incidentally, V M4} is an AC output voltage _{V M} in the motor 71 operating in the steady operation period.

After the time T14, the current consumed by the motor 71 further decreases, and in the steady operation state, the current consumed by the motor 71 (AC output current _IM ) becomes an almost constant value _IM4 . FIG. 3 (f) shows a state in which the current consumption of the motor 71 is _IM4. Then, the motor 71 is temporarily stopped when the amount of compressed air in the air tank 72 reaches a predetermined amount (see time T16 in FIG. 2). After that, the operation and control of the time T10 to the time T16 are repeated. Specifically, when the air remaining in the air tank 72 is below a predetermined value, the motor 71 starts rotating, the AC output current I _M starts to increase, the operation from time T10 (process) is resumed, the air tank 72 When the compressed air inside reaches a predetermined amount, the motor 71 is temporarily stopped.

-Comparative example-
FIG. 6 shows an AC output current waveform and a DC output current waveform at the time of starting the motor according to the comparative example. In the comparative example, the gouging device and the air compressor are connected to the engine drive working machine configured to be able to supply the DC power supply and the AC power supply as in FIG. On the other hand, in the comparative example, the control by the output control unit 43 as in the above embodiment is not performed.

As shown in FIG. 6, at time T10, when the motor of the air compressor starts to rotate and the output current from the AC output terminal of the engine drive working machine increases, the engine becomes overloaded. Then, although not shown, the output voltage of the AC output terminal drops and the motor of the air compressor cannot be started. As a result, as shown after the time T12 in FIG. 6, the starting current _IM7 may continue to flow in the motor, which may cause the air compressor to fail. Further, as the engine speed decreases, the output to the gouging device also decreases, so that the efficiency of the gouging work may decrease. On the other hand, by adopting the configuration of this aspect, it is possible to avoid the situation as shown in FIG.

As described above, according to this embodiment, the output control unit 43, when the AC output current I _M that is output from the AC output terminal 23 exceeds the first threshold value I _M1, is outputted from the DC output terminals 33 a DC output current _{I G} for controlling the output of the rectifier 31 to reduce from _{I G1 I G2 (I G1>} I G2). As a result, it is possible to prevent the engine 11 from being overloaded and the rotation speed from decreasing, so that the output from the AC output terminal 23 can be secured. That is, it is possible to avoid a decrease in the output voltage of the AC output terminal 23. As a result, the motor 71 of the air compressor 7 connected to the AC output terminal 23 can be easily and stably started even during the gouging work by the gouging device 8 connected to the DC output terminal 33.

Further, according to the present embodiment, the motor 71 can be started easily and stably regardless of the size of the engine 11. Specifically, for example, when the size of the engine 11 is small with respect to the power consumption of the motor 71, the rotation speed of the engine 11 tends to decrease. Such a case, or to increase the reduction amount P _G5 DC output at the time of activation of the motor 71, to reduce the reference value of the AC output current I _M (upper limit value) output from the AC output terminal 33 at its output suppression By doing so, the effect of preventing overload of the motor 71 can be enhanced. As described above, according to the present embodiment, there is a feature that the setting can be made according to the size (output capacity) of the engine 11 and the size of the motor 71 (particularly, the temporary increase in power consumption by the motor 71).

-Control operation of engine welder (2)-
In the configuration of FIG. 1, the output control unit 43, the difference between the amount of decrease in the DC output current I _G to be output from the DC output terminal 33, and the increase of the AC output current I _M that is output from the AC output terminal 23 as smaller, it may adjust the amount of decrease in the DC output current I _G. Hereinafter, description will be made with reference to FIGS. 4 and 5. In the following description, the differences from the "engine welding machine control operation (1)" will be mainly described, and the description of common parts may be omitted.

In this aspect (control operation (2)), as shown in FIGS. 4 and 5, the control of the output control unit 43 from the time T11 to the time T14 is different.

Specifically, the output control unit 43 obtains the amount of increase of the AC output current I _M that is output from the AC output terminal 23 from the first power calculating section 41. Further, the output control unit 43, since the acquired information of the DC output current I _G from the second power calculating unit 42 in real time, in accordance with the increase of the AC output current I _M, the DC output current I _G is reduced The rectifier 31 is controlled so as to do so. Then, as the difference between the amount of increase in the AC output current I _M and the reduction of the DC output current I _G is reduced, i.e., the amount of increase in the AC output current I _M and the reduction of the DC output current I _G is Control to be equal. In addition, "to be equal" means to be substantially equal. That is, even if the current control amount is slightly deviated based on the measurement accuracy of the ammeter, or the controlled current amount or control time is slightly deviated, it is included in "to be equal" in the present disclosure, and the same effect is obtained. can get.

4 and the time from the time T11 in FIG. 5 T14, shows a state of the control, the amount of increase in the AC output current I _M and the reduction of the DC output current I _G is equal. That is,
(Increase of the AC output current I _M) + (the amount of decrease in the DC output current I _G) = is controlled to be constant.

As described above, according to this embodiment, the output control unit 43, since the increase in the AC output current I _M and the reduction of the DC output current I _G is controlled to be equal, the output of the engine welder 1 It can be used more efficiently. That is, the current supplied to the gouging work apparatus 8 can be maximized while ensuring the output voltage of the AC power supply of the engine welding machine 1 and ensuring the starting stability of the motor 71 of the air compressor 7.

Although the preferred embodiment of the present invention and its modification have been described above, the technique according to the present disclosure is not limited to this, and can be applied to an embodiment in which modifications, replacements, etc. are appropriately performed. It is also possible to combine the components described in the above embodiment to form a new embodiment.

<Other embodiments>
For example, in the above embodiment, the control operation of the engine welder 1, (1) AC output current first threshold to each of the rising process and the falling process of _{I M I M1} and the second threshold _I M3 _(I M3 _{<I M1} how to make the provided control one each), and has been described (2) a method of controlling so as to reduce the difference between the reduced amount with an increased amount of the AC output current I _M of the DC output current I _G, the However, it is not limited to this. For example, discretely providing a plurality of first threshold I _M1 so that the value increases, each greater than the first threshold value I _M1, so as to reduce the DC output current I _G in response to a first threshold value I _M1 beyond The rectifier 31 may be controlled. The same applies to the second threshold I _M3, for example, discretely a plurality of second threshold I _M3 so that the value is lowered, each below the second threshold I _M3, the second threshold I _M3 falls below it may control the rectifier 31 so as to return the dc output current I _G in response.

7 and 8, provided with a first threshold value _{I M11, I M12} two such values is increased at an equal pitch, the two second threshold _{I M31, I M32} as a value at an equal pitch is lowered An example of the case where it is provided is shown. In FIGS. 7 and 8, the control of the output control unit 43 from the time T11 to the time T14 is different from the description so far. Note that FIG. 8A corresponds to FIG. 3B, and shows a state immediately before the output control unit 43 controls the rectifier 31 at time T11. Further, FIG. 8B shows a state immediately after the output control unit 43 controls the rectifier 31. In FIG. 8 (b), as compared with the case of FIG. 3 (c), reduction of the DC output P _G is halved. Then, upon reaching the first threshold I _M12 and the AC output current I _M is further increased as shown in FIG. 8 (c), so as to further reduce the DC output P _G as shown in FIG. 8 (d) I have to. That is, the same amount of DC output current _IG is reduced _{each time the first threshold value IM11} and _{IM12 are exceeded.} The same applies to the return of the DC output _{P G,} as shown in FIG. 8 (d) ~ FIG 8 (f), each of the second threshold _{I M31,} the DC output current of the same amount for each below _{I M32 I G} I am trying to restore. FIG. 8 (f) corresponds to FIG. 3 (e) (time T14), and the subsequent operations are the same as the above-mentioned “engine welder control operation (1)”. Thus, or decrease the DC output current I _G stepwise at an equal pitch, by or for returning, it is possible to more efficiently use the output of the engine welder 1.

Further, the second threshold value _IM3 may not be set. Specifically, the AC output current I _M is after a predetermined time exceeds a first threshold value I _M1, may be to return the DC output current I _G. For example, in case that the motor starting period Ts described above is known in advance, the AC output current I _M is a predetermined time according to the motor starting period Ts after exceeding the first threshold value I _M1 (e.g., a predetermined in Ts after the lapse of time to impart a margin period), it may be returned to the DC output current I _G.

INDUSTRIAL APPLICABILITY The present invention is extremely useful because it is possible to protect the device connected to the AC output terminal because it is possible to avoid a decrease in the output voltage of the AC output terminal.

1 Engine welder (engine drive work machine)
11 Engine 12 Generator 23 AC output terminal 31 Rectifier 33 DC output terminal 43 Output control unit CT1 1st ammeter (1st current measuring means)
CT2 2nd ammeter (2nd current measuring means)

Claims (7)

With the engine
A generator driven by the engine and having an AC power winding for generating AC power for an AC power source and a DC power source winding for generating AC power for a DC power source .
An AC output terminal for outputting AC power generated from the AC power winding
A first current measuring means for measuring an AC output current output from the AC output terminal,
A rectifier that converts AC power generated from the DC power supply winding into DC power,
A DC output terminal for outputting DC power rectified by the rectifier,
A second current measuring means for measuring the DC output current output from the DC output terminal, and
When the engine operates, AC power is generated from the AC power supply winding and the DC power supply winding, respectively, and the AC output current exceeds a predetermined first threshold value, the DC output current is reduced. An engine-driven working machine including an output control unit that controls the rectifier. In claim 1,
The output control unit restores the DC output current when the AC output current exceeds the first threshold value and then becomes less than the second threshold value smaller than the first threshold value. An engine drive working machine characterized by controlling the rectifier as described above. In claim 1,
The output control unit is an engine drive working machine characterized in that the rectifier is controlled so as to restore the DC output current after a lapse of a predetermined time after the AC output current exceeds the first threshold value. In claim 1,
The output control unit is an engine drive working machine characterized in that the decrease amount of the DC output current is adjusted according to the increase amount of the AC output current. In claim 4,
The output control unit is an engine drive working machine characterized in that the decrease amount of the DC output current is adjusted so that the difference between the decrease amount of the DC output current and the increase amount of the AC output current becomes small. In claim 1,
The DC output terminal is an engine drive work machine characterized by being an output terminal for connecting a gouging work device. In claim 1,
The first threshold is composed of a plurality of first thresholds whose values increase discretely.
The engine drive working machine is characterized in that the output control unit controls the rectifier so that the DC output current is gradually reduced as the AC output current exceeds each of the first threshold values.

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