JPS6213736Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to an automatic slowing device for an engine-driven welding machine with an AC auxiliary power supply, and in particular to a detector for detecting the presence or absence of an AC auxiliary power supply current and a welding current. The present invention relates to an engine-driven welding machine with an AC auxiliary power source that can simplify the process.

[Conventional technology]

As an engine-driven welding machine with an AC auxiliary power source of this type, the present applicant has already proposed the
There are ideas such as No. 70770 (Utility Application No. 55-144458). The engine-driven welding machine with an AC auxiliary power source slows down the engine when welding is stopped and when the AC auxiliary power source is not in use, thereby reducing noise and saving fuel. However, to detect the welding current and the AC auxiliary power supply current, a current transformer having a primary winding and a secondary winding is used. The coils through which the current flows must be electrically independent from each other, making the structure complex and extremely expensive.

[Problem that the invention attempts to solve]

Therefore, in view of the above circumstances, the present invention has been developed to detect the welding current and the AC auxiliary power supply current in order to control the slow speed of the engine. The object of the present invention is to provide an automatic slowing device for an engine-driven welding machine equipped with an AC auxiliary power source, which can easily detect the presence or absence of a power supply.

[Means and actions for solving problems]

In order to achieve the above object, the present invention provides an automatic slowing device for an engine-driven welding machine with an AC auxiliary power source that detects either the welding current or the AC auxiliary power source current to slowly control the engine. The automatic speed slowing device for engine-driven welding machines with AC auxiliary power supply is characterized by having an induction detection line wrapped around both the welding current load line and the AC auxiliary power supply current load line as a speed control detector. It is something to do. When a load current flows through either the welding current output line or the AC auxiliary power supply current output line, the induction detection line detects this and controls the rotational speed of the engine.

〔Example〕

Below, an embodiment of an automatic slowing device for an engine-driven welding machine with an AC auxiliary power source according to the present invention will be described. First, an engine-driven welding machine is constructed as shown in FIG. That is, in FIG. 1, 1 is an engine, 2 is directly connected to and driven by the engine 1,
It is also a welding generator equipped with an AC auxiliary power source.
A welding output terminal 3 and an AC auxiliary power supply output outlet 4 of this welding generator 2 are installed on a connection board 6. On the other hand, the engine 1 has a lever 5 for controlling the engine speed, and a plunger 5a is pivotally connected to the lever 5. The plunger 5a performs a suction operation when the solenoid S is energized. The lever 5 is tilted to control the rotational speed of the engine 1 from high speed to low speed. The lever 5 is urged back to the high speed side by a spring 5b.

FIG. 2 shows a first embodiment of an automatic slowing device for controlling the drive of the solenoid S.

The welding generator 2 is a rotating field type generator,
In order to obtain a welding output, the main armature winding has a three-phase star connection, and this main armature winding 7 is connected to a three-phase full-wave rectifier 8, and a reactor L is connected to the cathode of the three-phase full-wave rectifier 8. A welding rod 9 is connected through the welding rod 9, and a welding base material 10 is connected to the anode of the three-phase full-wave rectifier 8. On the other hand, the AC auxiliary power supply armature winding 11 is connected in series to the U-phase one of the main armature windings 7, and the AC auxiliary power supply armature winding 11 and the U-phase of the main armature winding 7 are connected in series. The AC auxiliary power output outlet 4 is connected to the AC auxiliary power supply and the V phase so that the auxiliary power supply can be taken out. The electromotive force induced in the armature winding 11 for AC auxiliary power supply is applied in the same direction as the vector sum of the electromotive force induced in each of the U phase and V phase of the main armature winding 7, and in a linear direction. Armature winding 1 for AC auxiliary power supply so that
1 is wound around the stator at an electrical angle θ of 30 degrees with respect to the U-phase of the main armature winding 7. A current transformer C/T-1 is interposed between the V phase of the main armature winding 7 and the three-phase full-wave rectifier 8 in order to extract a field current proportional to the output current component, that is, the welding current component. A rectifier 12 is connected to the current transformer CT-1 via a resistor _R1 for ratio selection, and a variable resistor _VR1 for adjusting the field current and a slip ring 13 are interposed in the rectifier 12 to adjust the field current. Winding 14 is connected. On the other hand, a three-phase full-wave rectifier 20 is provided between the input end of the three-phase full-wave rectifier 8 and the main armature winding 7, and the three-phase full-wave rectifier 20 extracts and rectifies the three-phase output. , a ratio selection resistor R ₂ , and further a field winding 14 is connected via the field current adjusting variable resistor VR ₁ and a slip ring 13 . Then, the output line 31 between any phase of the main armature winding 7, for example, the U phase and the three-phase full-wave rectifier 8, and the main armature winding 7 and the armature winding 11 for AC auxiliary power supply. A current transformer as a detector for automatic slow speed control by winding an induction detection wire 33 around both the output wire 32 and the AC auxiliary power output outlet 4.
It is called CT-2. An automatic speed reduction device 21 including a solenoid S is connected to the current transformer CT-2. In this case, the induction detection wire 33 can be drawn out from the wiring cord inside the automatic speed reduction device 21 and wound around the output wires 32 and 31 several turns.

Then, in order to perform welding, a welding rod 9 and a welding base material 10 are used.
When these are short-circuited, a short-circuit current flows through the output line 31, and the current transformer CT-2 detects this short-circuit current, and the automatic speed reduction device 21 controls the engine to the rated operation. Also, when the AC auxiliary power supply current is taken out from the AC auxiliary power output outlet 4, the above current transformer
The CT-2 detects the AC auxiliary power supply current, and the automatic speed reduction device 21 controls the engine to the rated operation in the same manner as described above. When neither the welding current nor the AC auxiliary power supply current is detected, the current transformer CT-2 controls the engine to operate at a low speed using the automatic speed reduction device 21.
On the other hand, when there is no load, the current supplied to the field winding 14 is supplied to the field winding 14 after rectifying the no-load voltage of the main armature winding 7 by a three-phase full-wave rectifier 20.
Donate to 4. During welding, the output voltage of the main armature winding 7 decreases, so the output voltage of the main armature winding 7 is rectified by the three-phase full-wave rectifier 20 and the field winding 14 is
Not enough to provide. Therefore, during welding, a part of the welding current is taken out by the current transformer CT-1 and supplied to the field winding 14 via the rectifier 12. In this case, since the three-phase full-wave rectifier 20 prevents backflow, the flow from the rectifier 12 through the three-phase full-wave rectifier 20 to the three-phase full-wave rectifier 8 never occurs. Resistor R ₁ and resistor R ₂ are current transformer CT-2
The current value does not change between when supplying current to the field winding 14 from the main armature winding 7 and when supplying current to the field winding 14 from the main armature winding 7 via the three-phase full-wave rectifier 20. , is set so that a substantially constant value is provided.

FIG. 3 shows a second embodiment, in which the field winding 14 is provided with slip rings 13, 13 and a variable resistor VR for adjusting the field current, without using the three-phase full-wave rectifier 20 in the first embodiment. ₁ , which is connected to the output end of the three-phase full-wave rectifier 8 with a ratio selection resistor _R2 interposed therebetween. In this case, unless the resistance value from the output end of the rectifier 12 to the field winding 14 side is extremely smaller than the resistance value from the output end of the rectifier 12 to the output end side of the three-phase full-wave rectifier 8, A diode (not shown) for preventing backflow is inserted between the output terminal and the output terminal of the three-phase full-wave rectifier 8.

In other words, the three-phase full-wave rectifier 8 is connected to the main armature winding 7.
The three-phase AC output is three-phase full-wave rectified and supplied to the welding rod 9 and the welding base metal 10, and the output voltage component is proportional to the field winding 14. be.

An output line 34 is located on the cathode side of the three-phase full-wave rectifier 8 and further on the welding rod 9 side from the connection point A where the output voltage component is taken out as a field current.
The induction detection line 33 of the current transformer CT-2 for automatic slow speed control is interposed between the two. This current transformer
CT-2 is an output line 32 that connects the V phase of the main armature winding 7 and one end of the AC auxiliary power output outlet 4.
It is something that was mediated by A drive circuit 17 is connected to the current transformer CT-2 via a detection circuit 15 and a timer circuit 16, and this drive circuit 17 controls the energizing operation of the solenoid S.

Therefore, when welding rod 9 and welding base metal 10 are first short-circuited to perform welding, a short-circuit current flows,
Current transformer CT-2 detects this. Then, the detection circuit 15 deenergizes the solenoid S via the timer circuit 16 and the drive circuit 17, tilts the lever 5 of the engine speed control device toward the high speed side by the return urging force of the spring 5b, and causes the engine 1 to rotate at high speed. Then, a predetermined welding power is applied between the welding rod 9 and the welding base material 10. By the way, current transformer
Although the CT-2 is interposed on the DC output side of the three-phase full-wave rectifier 8, it is not only possible to control the short-circuit current when the welding rod 9 and the welding base metal 10 are short-circuited, but also the short-circuit current between the welding rod 9 and the welding base metal
It also accurately detects the welding current when an arc occurs between 0 and 0. That is, even when rectified by the three-phase full-wave rectifier 8, there is a ripple component in the welding current, and furthermore, the arc generation state, the melting state of the welding rod 9, the distance between the welding rod 9 and the welding base metal 10, etc. Since the welding current can vary instantaneously, from direct current to direct current, depending on various conditions, the current transformer CT-2 can accurately detect the welding current during welding at all times. When the welding operation is stopped, no welding current is detected in the current transformer CT-2, but the solenoid S is kept deenergized via the drive circuit 17 for the time set internally by the timer circuit 16. The high speed rotation of the engine 1 is maintained for a certain period of time from the time of stopping. If the high speed rotation of the engine 1 is maintained for only a certain period of time in this manner, if the arc is accidentally broken during welding work, it is easy to generate a re-arc. After a certain period of time has elapsed, the drive circuit 17 energizes the solenoid S to tilt the lever 5 toward the low speed side against the biasing force of the spring 5b, thereby causing the engine 1 to rotate at a low speed.

Also, when an electrical tool, lighting fixture, etc. is connected to the AC auxiliary power output outlet 4 and used, the AC auxiliary power current is detected by the current transformer CT-2,
Similarly to the above, the solenoid S is deenergized via the detection circuit 15, timer circuit 16, and drive circuit 17. Therefore, the lever 5 is tilted toward the high speed side by the return urging force of the spring 5b, and the engine 1 rotates at high speed. If you stop using the AC auxiliary power supply,
After the time set in the timer circuit 16 has elapsed, the solenoid S is energized via the drive circuit 17, thereby causing the engine 1 to rotate at a low speed.

By the way, the detection circuit 15 of the present invention has a circuit configuration as shown in FIG. This detection circuit 15
After converting the welding current or AC auxiliary power supply current, that is, the load current, into voltage, the semi-fixed resistor R3 for sensitivity adjustment is clipped to reduce the voltage to a constant low voltage value, so that the polarity is opposite to that of _R3 . It has diodes D ₁ and D ₂ connected in parallel, and further includes a comparator 18 that outputs a detection signal depending on the presence or absence of the load current, that is, the detection voltage. When a load current is detected by the current transformer CT-2, it is converted into a voltage by a semi-fixed resistor _R3 for sensitivity adjustment. When the resistance value of the semi-fixed resistor _R3 for sensitivity adjustment is varied,
The slope of the characteristic curve of the detected voltage value between the terminals with respect to the value of the load current changes. Therefore, the smaller the resistance value of the sensitivity adjusting semi-fixed resistor _R3 , the smaller the detected voltage value with respect to the load current, and the lower the sensitivity. Detection voltage is 2 diodes
It is clipped by D ₁ and D ₂ and its forward voltage drop is suppressed to a constant voltage value of, for example, about 0.7 volts. These diodes D ₁ and D ₂ are -0.3 with respect to the voltage value of the negative terminal (-) of the comparator 18.
This is to prevent the comparator 18 from being damaged if a voltage with a difference of more than volts is applied to the input terminal (+). That is, current transformer CT
Even if an excessive current, especially an excessive welding current, flows through the primary side of current transformer CT-2, high voltage will not occur on the secondary side of current transformer CT-2. 18 damage can be prevented. Diode _D1 , _D2
The detected voltage clipped by the voltage dividing resistor
After the voltage is divided to a predetermined value by R ₄ and R ₅ , the comparator 18
is input to the input terminal (+) of This input voltage is a constant value regardless of the load current value, and when the load current is detected by the current transformer CT-2, the constant current source
The comparator 18 outputs an output signal exceeding the set voltage value determined by the setting resistors R ₆ and R ₇ by B ₁ .
This output signal is input to the timer circuit 16 shown in FIG. 3, which operates as described above.

Further, a current transformer is interposed on each of the output side from which the AC auxiliary power supply current is taken out and the output side of the three-phase full-wave rectifier that rectifies the DC welding output to take out, and each current transformer and the A NOR circuit is interposed between the connected detection circuit 15, and when each current transformer detects at least one of the welding current and the AC auxiliary power supply current, the automatic speed reduction device control is performed in the same manner as described above. It is also possible to do so.

[Effect of idea]

As described above, the automatic slowing device for an engine-driven welding machine with AC auxiliary power supply according to the present invention is used as a detector for detecting welding current and AC auxiliary power supply current in order to slowly control the engine. Since the induction detection line is routed around both the output line and the output line of the AC auxiliary power supply current, the wiring cord inside the automatic speed reduction device 21 is pulled out to the outside as the induction detection line, and each of the output lines is connected to the output line. Since it is sufficient to simply run the wires around the wire, the structure is extremely simple, does not require complicated or complicated wiring work, and can be produced at a low cost, making it extremely convenient in practice.

[Brief description of the drawings]

FIG. 1 is a specific configuration diagram of an engine-driven welding machine with an AC auxiliary power source according to the present invention, and FIG. 2 is a circuit diagram showing a first embodiment of an automatic slowing device for an engine-driven welding machine with an AC auxiliary power source. FIG. 3 is a circuit diagram showing the second embodiment, and FIG. 4 is a schematic diagram of the detection circuit. 1...Engine, 2...Welding generator, 3...
Welding output terminal, 4... AC auxiliary power output outlet, 5... Lever, 6... Connection board, 7... Main armature winding, 8... Three-phase full-wave rectifier, 9... Welding rod, 10 ... Welding base material, 11 ... Armature winding for AC auxiliary power supply, 12 ... Rectifier, 13 ... Slip ring, 14 ... Field winding, 15 ... Detection circuit,
CT-1, CT-2...Current transformer, L...Reactor, _R1 , _R2 ...Resistance for ratio selection, S...Solenoid.

Claims (1)

[Scope of utility model registration request] In an automatic slowing device for an engine-driven welding machine with an AC auxiliary power source that detects either the welding current or the AC auxiliary power supply current to slowly control the engine, the detector for automatic slow speed control detects either the welding current or the AC auxiliary power supply current to slowly control the engine. An automatic slowing device for an engine-driven welding machine with an AC auxiliary power source, characterized in that an induction detection line is wound around both the output line and the output line of the AC auxiliary power source current.