JP2001289089A - Revolution speed control device for engine-driven type welding generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an engine-driven type welding generator reduced in noise generation and improved in fuel consumption. SOLUTION: This revolution speed control device for an engine-driven type welding generator is provided with command elements VR, SW for forming command signals related to the revolution speed, an alternating current load detecting circuit DET1 for detecting alternating current output to form an alternating current load detection signal, a circuit DET2 for detecting welding output to form a signal indicating the size of welding load, and a control circuit for supplying an actuator AT with a control signal for regulating engine speed. The generator is operated at a first set revolution speed of medium speed or high speed during alternating current single output, operated at a second set revolution speed in a range of low speed or high speed during welding single output, and operated at a third set revolution speed corresponding to the added output of alternating current output and welding output during welding output including alternating current output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine-driven welding generator that generates an AC output together with a welding output, and more particularly, to rotating an engine according to the magnitude of a welding current of the welding generator and the presence or absence of an AC output. Related to those driven by numbers.

[0002]

2. Description of the Related Art In general, an engine-driven welding generator that generates an AC output as an auxiliary work power supply in addition to a welding output is widely used.

[0003] In this case, when the AC output as a work auxiliary power source and the welding output as a welding power source are used simultaneously, the engine speed is controlled at a high speed in accordance with the engine output speed by giving priority to the AC output. When there is no AC output, the motor is operated at a rotation speed corresponding to the welding output.

[0004] As described above, the engine has two types of generator use status, and it is necessary to operate the engine rationally so as to conform to both.

[0005]

Here, the engine-driven welding generator may be used, for example, in a situation where the construction site is a residential area and night work is required. Further, there are problems in operating the engine, such as reducing exhaust gas and minimizing fuel consumption.

Therefore, it is necessary to optimize the operation of the engine-driven welding generator while taking into account noise and fuel consumption without running the engine at high speed unnecessarily.

The present invention has been made in consideration of the above points, and has as its object to provide an engine-driven welding generator that reduces generated noise as much as possible and improves fuel economy as much as possible.

[0008]

According to the present invention, there is provided an engine provided with an actuator for adjusting an operation speed, and a generator driven by the engine to generate a welding output and an AC output. A rotational speed control device for an engine-driven welding generator, wherein the rotational speed of the engine is controlled by adjusting the actuator. And an AC load detection circuit for detecting the AC output to form an AC load detection signal, and a welding load detection circuit for detecting the welding output to detect a welding load and to generate a signal indicating the magnitude of the welding load. And, based on a command signal from the command device, taking into account each signal from the AC load detection circuit and the welding load detection circuit, And a control circuit for providing a control signal to the actuator for adjusting the rotation speed of the engine, and operating the engine at a first set rotation speed that is a medium speed or a high speed suitable for the AC output at the time of the AC output alone. ,
At the time of welding alone output, the engine is operated at the second set rotation speed which is the rotation speed according to the output in the low speed or high speed range, and at the welding output including AC output, the output obtained by adding the AC output and the welding output to the output. The present invention provides a rotation control device for an engine-driven welding generator, wherein the engine is operated at a third set rotation speed that is a corresponding rotation speed.

[0009]

FIG. 1 is a block diagram showing a basic configuration of an embodiment of the present invention. In this embodiment, a microcomputer MC is used to control the rotation speed of the engine, and the current detector DET1 is used.
Output current from the current detector DET2, welding output voltage from the voltage detector VD, welding current set value from the welding current regulator VR, and ON / OFF of the rotation control switch SW. It is provided as an input to the computer MC, and the microcomputer MC operates the governor control device GC and controls the operation of the chopper control circuit CC.

As described above, the operation of the embodiment shown in FIG. 1 is controlled by the operation of the microcomputer MC. The microcomputer MC has four input analog-to-digital conversion ports A / D, one output digital-to-analog conversion port D / A, and two input ON / OFF ports.
It has an off signal port and two output on / off signal ports.

The four A / D input ports are supplied with a detection signal of the current detector DET2, a detection signal of the voltage detector VD, a set value signal of the welding current regulator VR, and a detection signal of the potentiometer PM. The two input ON / OFF signal ports are supplied with an AC load presence / absence signal from the control circuit IC and a signal from the rotation control switch SW.
Relays L1, L
2 is provided with an activation signal.

The detection signal of the current detector DET2 is input to an A / D input port, and then converted into an on / off signal corresponding to the presence or absence of a load by a level determination inside the microcomputer MC. Is converted to a digital signal corresponding to the current value. That is, the microcomputer MC forms two signals based on the detection signal of the current detector DET2. The microcomputer MC has one D / A output port.
A current control signal is output from the A output port to the control circuit CC.

On the other hand, the generator G outputs an output generated by being driven by the engine E, and then converts the output through a rectifier REC1 to a direct current, which is applied to an inverter IV. , On the other hand, after being DC-converted by the rectifier REC2,
And supplied to a welding output terminal as a welding output.

The inverter IV includes a control circuit IC
Is the inverter IV based on the detection current of the current detector DET1.
And a signal indicating the presence or absence of an AC load is given from the control circuit IC to the microcomputer MC.
As a result, the microcomputer MC has the engine E
The governor control device GC is operated so as to operate at a medium speed.

The output of the generator G, which is DC-converted by the rectifier REC2, is DC-DC converted by the chopper CH and supplied to the welding output terminal. This chopper CH
A control signal is given from the control circuit CC to form a welding output, which is supplied to a welding output terminal. The control circuit CC is supplied with a control signal formed by the microcomputer MC taking into account the detection current of the current detector DET2 and the welding output voltage of the voltage detector VD to the set value of the welding current regulator VR.

In the control circuit CC, the detection current of the current detector DET2 is compared using the control signal supplied from the D / A port of the microcomputer MC as a reference signal, and the chopper CH is controlled based on the comparison result. .

The governor control device GC adjusts the governor EG provided in the engine E. The governor EG is controlled by rotating the motor M forward or backward to change the feeding length of the cable wound around the pulley PL. Is operated to change the rotation speed of the engine E. The forward / reverse switching of the motor M is performed by switching the contacts of the relays L1 and L2, and an energizing signal for the relays L1 and L2 is given from the microcomputer MC to each of the relays L1 and L2. Then, the rotation amount of the motor M is fed back to the microcomputer MC by a potentiometer PM connected to the motor M.

FIG. 2 is a flowchart showing the operation of the embodiment shown in FIG. The operation of the embodiment of FIG. 1 will be described based on this flowchart.

When a key switch as a power switch (not shown in FIG. 1) is turned on, the process proceeds from the start to step S1, where it is determined whether the rotation control switch SW is on. If it is not on, it means that the engine is operated at high speed without suppressing the rotation. The relay L1 is energized in step S11, and the motor M is rotated forward in step S12.

The forward rotation of the motor M is performed until the potentiometer voltage PV reaches the maximum value in step S13. When the value reaches the maximum value, the process proceeds to step S14 to deactivate the relay L1, then stops the motor M in step S15, and controls the engine governor EG in step S70. At this time, the engine governor EG operates the engine E at the highest speed. Then, step S1
The operation to return to is repeated.

On the other hand, if the rotation control switch SW is ON, the process proceeds from step S1 to step S2, where it is determined whether or not there is a load, that is, whether or not there is a load regardless of an AC load or a welding load. If there is a load, the process proceeds to step S21 and subsequent steps.

In step S21, if it is one of the AC load and the welding load, the process proceeds to step S22, and if both, the process proceeds to step S41 and thereafter. Here, it is determined that the load is an independent load, and the process proceeds to step S22 to determine whether the load is an AC load. If the load is an AC load, the process proceeds to step S23 to energize the relay L1, and the process proceeds to step S24 to rotate the motor M forward. As a result of this forward rotation, step S
If it is determined at 25 that the potentiometer voltage PV has reached the set value (1), the relay L1 is deactivated at step S26. As a result, the motor M is stopped in step S27. This position is a medium speed position which is somewhat lower than the highest speed. Then, the process shifts to step S70 to operate the engine E at a medium speed.

Next, as a result of the determination in step S22,
If the load is not the AC load, the process proceeds to step S28, and it is determined whether the potentiometer voltage PV is smaller than the set value (2), that is, an arbitrarily set value.

If it is smaller, it is necessary to increase the potentiometer voltage, and the process proceeds to step S29 to energize the relay L1, and the motor M is rotated forward in step S30. When the voltage of the potentiometer PM reaches the set value (2), the process proceeds from step S31 to step S32, and the relay L1 is deactivated. This is the position corresponding to the set value (2).
The process proceeds to engine governor control in step S70.

On the other hand, when the potentiometer voltage PV is larger than the set value (2) by comparing the potentiometer voltage PV with the set value in step S28, the relay L2 is energized in step S34. Then, a reverse rotation of the motor M is performed in step S35, and the potentiometer voltage PV is set to the set value (2) in step S36.
It is continued until it is determined that has been reached. If it has reached, the relay L2 is deenergized in step S37, and step S33
, And shifts to the engine governor control in step S70.

Next, the case where the result of the determination in step S21 is that an AC load and a welding load coexist will be described.
At this time, the process moves from step S21 to step S41. In step S41, the set value (1) and the set value (2) are added. If the potentiometer voltage PV is smaller than the added value in the determination in step S42, the energizing of the relay L1 and the forward rotation of the motor M are performed in steps S43 to S46, and the potentiometer voltage P
After increasing V, the motor is stopped in step S47, and the engine governor control is performed in step S70.

On the other hand, if the potentiometer voltage PV is larger than the added value in the judgment in step 42, the energization of the relay L2 and the motor M in steps S48 to S51.
After the potentiometer voltage PV is reduced by performing the reverse rotation of the above, the motor is stopped in step S47, and the engine governor control is further performed in step S70.

Finally, if there is no AC load or welding load, the process proceeds from step S2 to step S3. Step S3
Then, it is determined whether or not the potentiometer voltage PV is smaller than the minimum value.
The process goes to 1 to energize the relay L2, and the motor M is rotated reversely in step S62. Then, when it is determined in step S63 that the potentiometer voltage PV has reached the minimum value, the process proceeds to step S64, the relay L2 is deenergized, and the motor M is stopped in step S65, and step S70 is performed.
Performs engine governor control.

If the potentiometer voltage PV is smaller than the minimum value in step S3, the process returns to step S1, and
The circulation operation through steps S2 and S3 is repeated.

FIG. 3 shows another embodiment of the present invention, which is different from the embodiment of FIG. 1 and shows a circuit constituted by combining various elements without using a microcomputer.

The embodiment shown in FIG. 3 has three amplifiers EA1-EA3 and an analog switch AN as main components.
1-AN3 is an analog circuit configured using the slowdown circuit SD shown in FIG. 4 and the motor drive circuit MD shown in FIG. The embodiment shown in FIG. 3 is different from the embodiment shown in FIG. 3 in that the rotational speed at the time of the AC-only load is medium, whereas the embodiment shown in FIG. Perform the operation.

The amplifier EA1 has its + input terminal supplied with a detection signal of an AC output current detector DET1 through an analog switch AN1 and a rotation control switch SW connected thereto. Further, a minus input terminal of the amplifier EA1 is connected to a rotation setting device VR2 which is interlocked with the current regulator VR1.
Are connected. The output of the current regulator VR1 is given to the chopper control circuit CC as a reference signal,
The signal is matched with the feedback signal from the current detector DET2 and used for controlling the chopper CH.

The output of the amplifier EA1 is the + of the amplifier EA2.
The input terminal is connected to the-input terminal of EA3. The minus input terminal of the amplifier EA2 and the plus input terminal of the amplifier EA3 are supplied with a signal extracted from the output of the generator G by the engine rotation detector RD and subjected to voltage conversion by the frequency-voltage converter F / V. Then, these two amplifiers E
The outputs of A2 and EA3 are applied to a motor drive circuit MD (FIG. 5), and the motor drive circuit MD drives the motor M of the governor control circuit GC.

The slowdown circuit (FIG. 4) is supplied with both detection signals of a current detector DET1 for detecting a current of an AC output and a current detector DET2 for detecting a current of a welding output, and the amplifiers EA1, Analog switches AN1, AN2, AN3 inserted on the input side of EA2, EA3
Used to control the opening and closing of

The slowdown circuit SD shown in FIG. 4 has first to third comparators CP11 to CP13 and an AND circuit A10 as main components, and is supplied with a current detection signal of an AC output and a welding output. Thus, a control signal for turning on and off the analog switches AN1 to AN3 is formed.

The motor drive circuit MD shown in FIG. 5 includes a voltage / frequency conversion circuit V / F and fourth to sixth comparators CP.
21-CP23, AND gates A21-A25, inverters INV1-INV3, an insulating circuit INS, and a bridge energizing circuit including transistors Tr11-Tr14 are main components, and energize the motor M in accordance with inputs A, B, C, and D. .

Next, the operation of the circuits shown in FIGS. 3 to 5 will be described in the following six cases (1) to (6).

(1) When the rotation control switch SW is off In the circuit of FIG. 3, when the rotation control switch SW is off, the + input terminal of the amplifier EA1 has a resistor R1 connected to a + 12V power supply and a diode D1. , A divided voltage is applied from a series circuit of the resistor R4. And the amplifier EA1
Is connected to an input terminal of the engine rotation setting device VR2 by a resistor R.
A voltage formed as a divided voltage between R5 and R6 is applied through resistor R3.

The voltage applied to the + input terminal of the amplifier EA1 is set in advance so as to be higher than the maximum set voltage of the engine speed setting device VR2. The amplifier EA1 is
Since the output voltage is increased so that the input voltage of the-input terminal becomes equal to the input voltage of the + input terminal, the output voltage is fed back to the-input terminal through the feedback resistor R7, and thereby the voltage of the-input terminal is increased. Rises. The output voltage of the amplifier EA1 is equal to the resistances of the resistors R8 and R1.
3, and applied to the + input terminal of the amplifier EA2 and the-input terminal of the amplifier EA3 via R15.

The output of the engine rotation detecting device RD is supplied to the minus input terminal of the amplifier EA2 via the frequency-voltage converter F / V and the resistor R12. The amplifier EA3
The output of the frequency-to-voltage converter F / V is also supplied to the + input terminal of the inverter via the resistor R16.

Thus, the amplifier EA2 operates as an amplifier only when the voltage at the + input terminal is higher than the voltage at the-input terminal, and does not perform the amplification operation when the + input terminal voltage is lower than the-input terminal voltage. . And the amplifier EA2
Is fed back to the-input terminal via the feedback resistor R14.

Now, the generator G is operating at low speed and the amplifier E
It is assumed that a voltage lower than the positive input terminal voltage is applied to the negative input terminal of A2. This difference is largest when the generator G starts operating. This difference voltage is output from the output terminal of the amplifier EA2, and the diode D3 → the motor drive circuit MD →
The fuel supply to the engine E is adjusted through the path from the motor M to the engine governor EG, and the engine rotation speed increases.

This increase in the engine rotation speed is detected by the engine rotation detection device RD, converted into a voltage by the frequency-voltage converter F / V, and applied to the negative input terminal of the amplifier EA2 through the resistor R12. At this time, the amplifier E
Because there is a difference between each input voltage of both input terminals + and-of A2,
An output voltage corresponding to the voltage difference is generated, and the diode D3
Through the motor drive circuit MD, drives the motor M, and operates the engine governor EG in a direction to increase the speed of the engine E.

As a result, when the speed of the engine E increases, the output voltage of the engine rotation detecting device RD increases, the output of the frequency-voltage converter F / V increases, and the input applied to the negative input terminal of the amplifier EA2. The voltage also rises.

As the engine speed increases, the voltage applied to the-input terminal of the amplifier EA2 approaches the input voltage applied to the + input terminal thereof.
Output voltage decreases. The motor drive circuit MD controls the motor M according to the magnitude of the output voltage, and operates the engine governor EG so as to stop the increase in the speed of the engine E.

When the voltages at both input terminals + and-of the amplifier EA2 become the same potential, the output voltage of the amplifier EA2 approaches 0 V. Immediately before this, the upper limit switch LS-U of the governor controller GC operates. The input to the terminal A of the circuit MD disappears, and the motor M stops. In this state, the engine E performs high-speed constant-speed operation.

(2) When the rotation control switch SW is turned on (however, when there is no load) When the rotation control switch SW which has been turned off in the above (1) is turned on, an operation for lowering the engine speed is performed. Will be

When the rotation control switch SW is switched from off to on, the power supply +12 V is applied to the resistors R1 and R1 '.
The voltage divided by the resistor R4 connected in parallel to the resistor R1 'through the diode D1 is applied to the + input terminal of the amplifier EA1. Moreover, the + input terminal of the amplifier EA1 is set lower than the-input terminal. As a result, the output voltage of the amplifier EA1 approaches 0V. Therefore, the output of the amplifier EA1 is
2. Resistors R8 and R1 so as not to affect EA3.
3. The constant of R15 is selected.

In this case, since the AC load and the welding load are both no-load, the slowdown circuit SD outputs the signal P2 to H level.
(High, hereinafter simply referred to as H) and supplied to the analog switch AN3 to make it conductive (at this time, the signal P1 is
L (low, hereinafter simply referred to as L). ).

Then, the power supply +12 V is connected to the resistors R10 and R1.
The voltage obtained by voltage division by the series circuit of 1, ie, the low-speed position signal is applied to the + input terminal of the amplifier EA2 via the resistor R13 ', and to the-input terminal of the amplifier EA3 via the resistor R15'. This voltage is selected to be the same value as the frequency-voltage conversion voltage at the time of low-speed rotation.

When the rotation control switch SW is switched from off to on, the engine E is in a high-speed rotation state, so that the frequency-to-voltage converter F / V produces a higher voltage output than during low-speed rotation. This output is applied through resistor R12 to the-input terminal of amplifier EA2 and through resistor R16 to the + input terminal of amplifier EA3.

In the amplifier EA2, since the negative input terminal has a higher voltage, the difference between the two input terminals + and-is that the negative input terminal has a positive potential with respect to the positive input terminal. Is a voltage close to 0V.

On the other hand, in the amplifier EA3, since the voltage at the + input terminal is high and the voltage at the-input terminal is low, the amplifier EA3
Output voltage is initially high, this is the diode D4
To the motor drive circuit MD. Then, the motor M is driven, and the engine governor E is driven by the pulley PL.
G operates.

As a result, the engine E is initially operated at a high speed, but will soon be operated at a low speed because of no load. Then, as the speed decreases, the +
The input voltage of the input terminal approaches the voltage of the reference -input terminal. Accompanying this, the output voltage of the amplifier EA3 also decreases, and the engine speed decreases, resulting in a constant low-speed operation.

The diodes D3 and D4 inserted in the paths connecting the output terminals of the amplifiers EA2 and EA3 and the input terminal C of the motor drive circuit MD constitute an OR gate. The signal from the output terminal of the amplifier EA3 to the input terminal D of the motor drive circuit MD is for rotating the motor M in the forward direction (rotation toward the high speed side of the engine) or in the reverse direction (rotation toward the low speed side of the engine). , The motor rotates forward, and at 1 V or more, the motor rotates reversely.

(3) When the rotation control switch SW is turned on and a welding load is detected When the rotation control switch SW is turned on, the voltage at the + input terminal of the amplifier EA1 becomes lower than the voltage at the-input terminal, The output voltage of EA1 approaches 0V.

When a welding load is detected at this time, a voltage output is supplied from the current detector DET2 to the slowdown circuit SD. Thereby, the slowdown circuit SD sets the output signal P1 to H and the output signal P2 to L. Output signal P1
However, in order to make the analog switch AN2 conductive, the set voltage of the rotation setting device VR2 passes through the resistor R9 and the analog switch AN2, and one of them passes through the resistor R13 'and the amplifier EA.
2 is supplied to the + input terminal of the amplifier EA3 through the resistor R15 '.

In the initial stage of welding load detection, since the engine E is rotating at a low speed, in the amplifier EA2, the + input terminal has a high voltage and the-input terminal has a low voltage. Therefore, the output signal of the amplifier EA2 is formed as a voltage obtained by amplifying the difference between the signals of the two input terminals + and-, and supplied to the input terminal C of the motor drive circuit MD through the diode D3.

In the amplifier EA3, since the voltage at the + input terminal is low and the voltage at the-input terminal is high, no amplification operation is performed, and the output voltage approaches 0V. This is for rotating the motor M in the forward direction, and the input terminal D of the motor drive circuit MD is provided.
Given to. Therefore, the motor drive circuit MD causes the motor M to rotate forward according to the magnitude of the voltage applied to the input terminal C, so that the engine E operates at high speed.

As the speed of the engine E increases in this manner, the input voltage of the-input terminal of the amplifier EA2 increases, and the setting of the rotation setting device VR2 applied to the + input terminal via the amplifier EA1. Approaching value. For this reason, the output voltage of the amplifier EA2 decreases. And
When the degree of increase in the rotation speed of the engine E decreases and reaches the set value of the rotation setting unit VR2, the output voltage of the amplifier EA2 approaches 0 V, and the motor drive circuit MD stops driving the motor M. Therefore, the engine E operates at a constant speed. Thereby, the welding output is supplied from the welding generator G.

(4) When an AC Load is Detected During Welding When the generator G is operating at the set value set by the rotation setting device VR2, the AC load is detected by the current detector DET1. It is provided to the down circuit SD. In this case, the output signals P1 and P2 of the slowdown circuit SD do not change, and P1 is H and P2 is L. Therefore, the analog switches AN1 and AN2 are turned on, and the analog switch AN3 is turned off.

Therefore, a positive voltage corresponding to the AC load is applied to the + input terminal of the amplifier EA1 through the analog switch AN1. This causes a difference between the two input terminals + and-of the amplifier EA1, and a voltage proportional to the difference is formed as an output signal. The output signal of the amplifier EA1 passes through the resistor R8 and then passes through the resistor R13 to the amplifier EA1.
2 to the + input terminal and the amplifier EA3 via the resistor R15.
, Respectively.

The + input terminal of the amplifier EA2 is connected to the amplifier E
The output voltage of A1 is provided as an addition through resistors R8 and R13. The added amount means an added amount due to the detection of the AC load. This added amount is amplified by the amplifier EA2 and supplied to the motor drive circuit MD as an output signal through the diode D3. As a result, the motor drive circuit MD rotates the motor M in the forward direction and increases the speed of the engine E.

The amplifier EA3 does not perform an amplification operation because the voltage on the + input terminal side is low and the voltage on the − input terminal side is high, and the output voltage approaches 0V. For this reason,
A voltage signal close to 0 V is applied to the input terminal D of the motor drive circuit MD.

As the rotational speed of the engine E increases, the feedback signal of the engine speed from the frequency-to-voltage converter F / V passes through the resistor R12 to the amplifier EA2.
To the-input terminal. Then, the rotation speed of the engine E increases until the voltages at both input terminals + and-of the amplifier EA2 are balanced.

As a result, when the voltages at both input terminals + and-of the amplifier EA2 are balanced, the output voltage decreases and the motor M stops. At this time, the engine E operates at a constant speed.

(5) In the case where the AC load is eliminated from the state where the welding load and the AC load are present When the AC load is eliminated, the output of the current detector DET1 is eliminated. The output of the current detector DET1 is supplied to the slowdown circuit SD and the analog switch AN
1. The signal is supplied to the + input terminal of the amplifier EA1 through the resistor R2. Then, when the output of the current detector DET1 disappears, the voltage of the + input terminal of the amplifier EA1 decreases, the voltage of the-input terminal increases, and the amplification operation is not performed. Then, the output of the amplifier EA1 approaches 0V.

As a result, the voltage at the + input terminal of the amplifier EA2 and the voltage at the-input terminal of the amplifier EA3 tend to decrease. As a result, the amplifier EA2 stops performing the amplification operation. Then, the amplification operation is switched from the amplifier EA2 to the amplifier EA3.

The output voltage of the rotation setting device VR2 is equal to the resistance R
9, applied to the negative input terminal of the amplifier EA3 through the analog switch AN2 and the resistor R15 '. The voltage applied to the negative input terminal is reduced by the amount of the AC load being removed. Therefore, the voltage at the + input terminal of the amplifier EA3 increases and the voltage at the-input terminal decreases, and a voltage corresponding to the difference is formed at the output terminal of the amplifier EA3. This output voltage is fed back to the minus input terminal via the feedback resistor R17.

At this time, when the output voltage of the amplifier EA3 is 1 V or more, the motor drive circuit MD detects the voltage value of the input terminal D, rotates the motor M in the reverse direction, and lowers the speed of the engine E. When the speed of the engine E decreases, the amplifier E
The feedback signal of the engine speed input to the + input terminal of A3 decreases and becomes balanced with the voltage of the-input terminal. When equilibrated, the rotation of the motor M stops,
The rotation speed of the engine E becomes constant.

(6) When there is no welding load when there is no welding load When the welding load disappears, the output of the current detector DET2 becomes zero.
V, which is input to the slowdown circuit SD.
In response to this, the slowdown circuit SD outputs the signal P1 after a lapse of a preset slowdown time, for example, several seconds.
As L and the signal P2 as H. As a result, the analog switches AN1 and AN2 are turned off, and the analog switch AN3 is turned on.

The amplifier EA1 has a low input voltage to its + input terminal and does not perform an amplification operation. Further, the voltage of the + input terminal of the amplifier EA2 also decreases, and the amplifier EA2 does not perform the amplification operation. On the other hand, in the amplifier EA3, the power supply +12 V
Is divided by a series circuit of a resistor R10 and a resistor R11, and is applied via an analog switch AN3 and a resistor R15 ′. This divided voltage is a voltage that shifts to low-speed rotation, that is, slowdown.

In the initial stage of the transition to the low-speed rotation, the generator G
Is still rotating at high speed, so that the +
A high voltage is applied to the input terminal from the frequency-voltage converter F / V. For this reason, the amplifier EA3 has two input terminals +,
The voltage difference between-is large. Then, an output voltage corresponding to the voltage difference is output from the output terminal of the amplifier EA3.

The output of the amplifier EA3 is
D input terminal D. In the motor drive circuit MD, the magnitude of the input signal is determined. For example, if the input signal is 1 V or more, the motor M is rotated in the reverse direction to reduce the speed of the engine E as described above. Then, the engine speed feedback signal is applied to the + input terminal of the amplifier EA3 through the resistor R16.

In the initial stage where the engine speed is high, the voltage at the + input terminal of the amplifier EA3 is high and the voltage at the-input terminal is low. Then, as the engine speed decreases, the voltage difference disappears, and the output voltage of the amplifier EA3 also decreases. In response, the motor drive circuit MD reversely rotates the motor M to reduce the speed of the engine E.

When the speed of the engine E decreases, the amplifier E
When the voltage difference between the two input terminals + and-of A3 approaches equilibrium, and when the output of the amplifier EA3 approaches 0 V when the equilibrium is reached, the motor M stops rotating. The engine speed at this time is low. Actually, before the voltage difference between the input and output terminals + and-of the amplifier EA3 is balanced, the lower limit switch LS-L provided on the motor M operates, and the signal B is sent to the motor drive circuit MD. The motor M stops. At this time, the upper limit switch LS-U is kept off.

Next, the detailed configuration and operation of the slowdown circuit SD shown as a single block in FIG. 3 will be described with reference to FIG.

The slowdown circuit SD includes first to third comparators CP11 to CP13 and an AND gate A.
10 as main components, and current detectors DET1 and DE
Each of the current detection signals of T2 is provided as an input, and a signal P for performing on / off control of the analog switches AN1 to AN3 is provided.
1, P2 is output.

As described above, the slowdown circuit SD responds to the detection of the AC load by the current detector DET1 or the detection of the welding load by the current detector DET2.
Therefore, the operation will be described according to these detection modes.

(I) When a welding load is detected during low-speed rotation When the current detector DET2 detects a welding load current, a voltage signal corresponding to the current value is supplied to the control circuit and the slowdown circuit SD. The output of the current detector DET2 is supplied to the-input terminal of the first comparator CP11 through the diode D22 and the resistor R23. In the first comparator CP11,
The power supply voltage +12 V is divided by a series circuit of resistors R21 and R22 and compared with a reference voltage supplied to a + input terminal.

As a result of this comparison, if the output of the current detector DET2 is higher than the reference voltage, the first comparator CP11 generates an L output at the output terminal connected to the power supply + 12V via the resistor R24, R26, diode D23
And a charge / discharge circuit composed of a capacitor C21,
And AND gate A10. In response, the charge of the capacitor C21 is discharged via the resistor R26 and the diode D23, and the lower input terminal of the AND gate A10 goes low. As a result, the signal P2 output from the AND gate A10 becomes L.

The upper terminal of the resistor R26 connected to the upper terminal of the capacitor C21 is connected to the minus input terminal of the second comparator CP12 and the third comparator CP13.
To the + input terminal. In the second comparator CP12, the-input terminal is L, the + input terminal is H, and the output is H.

In this state, the signal P1 generated at the output terminal connected to the power supply + 12V via the resistor R30 of the second comparator CP12 becomes H, and the analog switches AN1 and AN2 (FIG. 3) ). Third
Has a negative input terminal of H and a positive input terminal of L
Thus, the signal at the output terminal connected to the power supply +12 V via the resistor R31 becomes L. In this state, the output of the third comparator CP13 is L, and the L signal is supplied to the upper input terminal of the AND gate A10 in the figure.

(Ii) When an AC load is detected during the welding operation at the set number of revolutions When an AC load is detected, the output signal of the current detector DET1 is input to the slowdown circuit SD. However, at this time, the current detector DET2 has already detected the welding load, and the detection output is given to the-input terminal of the first comparator CP11 through the diode D22. Therefore, the operation of the slowdown circuit SD does not change.

(Iii) When no AC load is applied during the operation with the welding load and the AC load: The operation of the slowdown circuit SD does not change because the welding load exists.

(Iv) When the state is changed from the state with the welding or AC load to the state without the load When the state is changed from the state with the welding or the AC load to the state without the load, the minus input terminal of the first comparator CP11 becomes L. .
On the other hand, the + input terminal becomes higher than the − input terminal, and the output becomes H. Thereby, a slowdown time (for example, 8 seconds) is started.

The slowdown time is set as the charging time of the charging / discharging circuit, and the power supply + 12V to the resistor R24,
This is the time during which the capacitor C21 is charged through R25 and R26. The voltage charged in the capacitor C21 is supplied to the second and third comparators CP12 and CP13.
A comparison result is output by comparing with a voltage formed by voltage division by the resistors R28 and R29.

The second comparator CP12 has a negative input terminal connected to a capacitor C2 which rises simultaneously with no-load detection.
1 and a + R input terminal is connected to a resistor R2.
8. A voltage divided by R29 is applied. And-
When the voltage of the input terminal exceeds the voltage of the + input terminal, the output changes from the previous H output to the L output.

On the other hand, to the third comparator CP13, the + input terminal is supplied with the rising voltage of the capacitor C21, and the − input terminal is supplied with the voltage divided by the resistors R28 and R29. Then, when the voltage of the + input terminal exceeds the voltage of the − input terminal, the current L output shifts to the H output, and the H signal is given to the AND gate A10.

As a result, the first gate is provided to the AND gate A10.
The AND condition is satisfied by the H signal supplied from the comparator CP11 of the above and the H signal supplied from the third comparator CP13, and an H output is generated to be supplied to the analog switch AN3 (FIG. 3) as a signal P2.

Next, the detailed structure and operation of the motor drive circuit MD shown in FIG. 5 will be described. The motor drive circuit MD includes signals A, B and amplifiers EA2, E from the upper limit switch LS-U and the lower limit switch LS-L of the governor control circuit GC shown in FIG.
The respective outputs C and D of A3 are supplied to control the current supplied to the motor M by a pulse frequency modulation method.
The main component is a voltage-frequency converter V
/ F, the fourth to sixth comparators CP21, CP22, C
P23, AND gate A21-A24, inverter IN
V1-INV3, an insulating circuit (photocoupler) INS, and a bridge circuit of transistors Tr11-Tr14.

In this circuit, the sixth comparator CP23 determines the forward or reverse rotation direction of the motor M. That is,
A reference voltage formed by voltage division by the resistors R47 and R48 is supplied to the reference input terminal R, and the amplifier EA3 is connected to the input terminal I.
When the output signal D shown in FIG.
When the signal D is higher than the reference voltage, an H signal is applied to the AND gate A24 and the inverter INV3 to invert the motor M, and when the signal D is lower than the reference voltage, an L signal is applied to rotate the motor M forward.

The voltage-frequency converter V / F, the fifth comparator CP22, and the sixth comparator CP23 perform speed control, stop control, and hunting prevention of the motor M. In the above description, only the rotation direction of the motor M has been described, but actually the rotation speed is also controlled to speed up the control operation.

First, the voltage-frequency converter V / F obtains a voltage input and forms a pulse output. When the input voltage is low, for example, a low frequency pulse of about 1 kHz is output,
When the input voltage increases, a high-frequency pulse of, for example, about 10 kHz is output. Then, the set rotation speed and the engine E
When the difference between the rotation speed of the engine E is large and the input voltage is high, a high frequency pulse is output to rotate the motor M at high speed.
At low speed. Thus, the rotation speed of the motor M is controlled in proportion to the difference between the set rotation speed and the engine rotation speed.

Next, the fourth comparator CP21 and the fifth comparator CP22 will be described. These are the resistors R4
1, the magnitude of the two reference voltages divided by the series circuit of R42 and R43 is compared with the signal C from the amplifier EA2, and the motor M is stopped.

In the fifth comparator CP22, the reference voltage supplied from the interconnection point between the resistors R42 and R43 and the resistor R
45 is compared with the signal C provided through
Becomes lower than the reference voltage, the fifth comparator CP22 outputs L
The output is given to AND gate A21. As a result, the AND gate A22 does not satisfy the AND condition, and as a result, the AND gates A23 and A24 also fail the AND condition, so that no output is given to the insulating circuit INS. As a result, the bridge circuit of the transistors Tr11-Tr14 stops supplying power to the motor M, and the motor M stops.

On the other hand, when the signal C becomes higher than the reference voltage, the stop of the motor M is released because the fifth comparator CP22 generates an H output.

The fourth comparator CP21 sets the level of the signal C when restarting the motor M after stopping it to be higher than that when the motor M is stopped, so that the engine E does not cause a hunting phenomenon. . That is, when the signal C provided via the resistor R44 becomes higher than the reference voltage provided from the interconnection point between the resistors R41 and R42, the output of the fourth comparator CP21 changes from L to H, and this signal is It is provided to one input terminal of AND gate A21. At this time, the H output from the fifth comparator CP22 is supplied to the other input terminal of the AND gate A21, and the H output is supplied to the AND gate A22.

As a result, the voltage of the AND gate A22 becomes negative.
An output that takes into account the output of the frequency converter V / F is formed and supplied to AND gates A23 and A24. The outputs of the AND gates A23 and A24 are supplied to the bridge circuit of the transistors Tr11 to Tr14 via the insulating circuit INS, and the energization control to the motor M is performed.

The second embodiment described with reference to FIGS. 3 to 5 is directed to an engine with a governor, but can also be applied to an engine without a governor.

FIGS. 6 (a) to 6 (c) show output current-output voltage characteristics in which a no-load voltage fluctuates due to rotation fluctuation as a welding generator by rotation control according to the present invention. As shown in FIG. 6A, the welding generator supplies an output with a control range between an output curve MAX at a high speed rotation and an output curve MIN at a low speed rotation due to rotation fluctuation.

At this time, in the small current range, the no-load voltage becomes small.
The output of the auxiliary winding having the characteristic shown in (b) is superimposed on the output of the welding winding to increase the voltage, so that an arc is stably generated even when the rotation speed of the welding generator decreases.

FIG. 6C shows a combined output characteristic of the welding winding and the auxiliary winding in which such measures are taken. That is, as shown in FIG. 6 (c), the output voltage of the auxiliary winding is superimposed in a small current range and the voltage is increased for the purpose of arc stabilization, and the output is increased. I follow it.

(Modification) In the above-described embodiment, the rotation speed control of the motor M is not explicitly described and the rotation speed is controlled, but it may be appropriately selected according to the function of the engine governor.

In the case of controlling the speed, the rotation speed of the motor M is controlled by the pulse frequency modulation method. However, the rotation speed can be similarly controlled by the pulse width modulation method.

Although the engine speed is detected from the potentiometer PM in the governor control device GC and from the output of the generator G, the engine speed itself may be detected. An alternative signal may be used.

[0107]

As described above, the present invention supplies an output corresponding to a welding load arbitrarily set by a rotation setting device when operating a welding generator for supplying an AC output in addition to a welding output, as described above. Since the engine is operated at the optimum rotation speed to supply the output obtained by adding both outputs according to the presence or absence of the AC load, the engine can be operated at the optimum rotation speed corresponding to the welding output and the AC output, Low fuel consumption and low noise are achieved under most working conditions except when the maximum output is required.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a first example of the present invention.

FIG. 2 is a flowchart showing the operation of the embodiment of FIG. 1;

FIG. 3 is a block diagram showing the overall configuration of a second embodiment of the present invention.

FIG. 4 is a circuit diagram showing a detailed configuration of a slowdown circuit used in the embodiment of FIG. 3;

FIG. 5 is a circuit diagram showing a detailed configuration of a motor drive circuit used in the embodiment of FIG. 3;

6 (a) shows basic output characteristics of a welding generator used in the present invention, and FIG. 6 (b) shows an auxiliary winding used to correct the output characteristics of FIG. 6 (a). The characteristics are shown in FIG.
FIG. 7 is a characteristic diagram showing output characteristics obtained by combining the respective characteristics of FIGS. 6A and 6B.

[Explanation of symbols]

 E engine G generator EG engine governor GC governor control device PL pulley M motor L1, L2 relay PM potentiometer MC microprocessor VD voltage detector IV inverter (quadrature converter) IC inverter control circuit CT current transformer DET current detector VR welding Current regulator SW Rotation control switch CH Chopper CC Chopper control circuit VR1 Current regulator VR2 Rotation setting device AN Analog switch EA Amplifier SD Slow down circuit MD Motor drive circuit RD Engine rotation detector F / V Frequency-voltage converter CP comparator V / F Voltage-frequency converter A AND gate INV Inverter (signal inverter) INS Isolation circuit

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Toru Hiroi 2-8-8 Yoshinodai, Kawagoe-shi, Saitama 65 Denyo Corporation Technical Department (72) Inventor Osamu Suzuki 2--8 Yoshinodai, Kawagoe-shi, Saitama 65 Den-Yo Corporation Engineering Department (72) Inventor Yasumasa Mizuno 2--8, Yoshinodai, Kawagoe-shi, Saitama 65 Den-Yo Corporation Engineering Department F-term (reference) 3G093 AA17 AB05 BA19 BA32 CA04 CA10 CA11 DA01 DB19 DB20 DB26 EA03 EB08 EC02 FA11 4E082 CA04 DA01 DA02 EA20 EF30

Claims (4)

[Claims] An engine provided with an actuator for adjusting an operation speed, and a generator driven by the engine to generate a welding output and an AC output, and the actuator is adjusted by adjusting the actuator. In an engine drive welding generator generator rotation speed control device adapted to control the rotation speed, a command device for forming a command signal relating to the rotation speed of the engine in accordance with an operation; and an AC load detection signal by detecting the AC output. An AC load detection circuit that forms a signal, a welding load detection circuit that detects the welding output and forms a signal indicating the magnitude of the welding load and the welding load, and a command signal from the command device. A control signal for adjusting the number of revolutions of the engine in consideration of each signal from the AC load detection circuit and the welding load detection circuit, A control circuit to be provided to the actuator; operating the engine at a first set rotational speed that is medium or high speed suitable for AC output when AC alone is output; and output in a low to high speed range when welding alone is output. The engine is operated at a second set speed which is a speed according to the above, and at the time of welding output including an AC output, a third set speed which is a speed according to an output obtained by adding the AC output and the welding output A rotation control device for an engine-driven welding generator, wherein the engine is operated. 2. The rotation control device for an engine-driven welding generator according to claim 1, wherein the command device forms a command signal corresponding to the first to third set rotation speeds. Rotation control device for welding generator. 3. The rotation control device for an engine-driven welding generator according to claim 2, wherein the command unit generates a constant speed command signal for operating the engine at a constant speed regardless of the magnitude of the load. A rotation control device for an engine-driven welding generator as described above. 4. The rotation control device for an engine driven welding generator according to claim 3, wherein the constant speed command signal is a command signal for operating the engine at high speed.