JP2556629Y2 - Welder fan control - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a fan control device for a welding machine, in particular, a structure in which a shunt resistor is connected between a switching element and a ground, and the drive of the fan is controlled based on the current flowing through the shunt resistor. And a fan control device for the welding machine.

[0002]

2. Description of the Related Art In a battery-driven welding machine controlled by an electronic circuit, a switching element for controlling the welding current is used. A switching element for controlling a large current is fixed to a heat sink to dissipate heat. Usually, a fan is used to further increase the cooling efficiency.

This fan uses a battery as a welding power source as a power source. The rotation and stop of the fan of the conventional welding machine are determined in conjunction with the ON / OFF of the main switch.

[0004]

[Problems to be Solved by the Invention] In the conventional configuration in which the control of the rotation and stop of the fan is linked to the main switch, the fan continues to rotate even when welding is not being performed, so that there is a large loss and an unacceptable loss. It was economical and had the drawback that if the main switch was accidentally left on, the current consumption of the fan would drain the battery.

An object of the present invention is to solve the above-mentioned drawbacks by detecting a current flowing through a shunt resistor connected between the switching element and the ground, and rotating and stopping the fan based on the detected current. It is an object of the present invention to provide a fan control device for a welding machine, which controls the welding force.

[0006]

To achieve the above object, a fan control device for a welding machine according to the present invention includes a switching element (3) for turning on and off a voltage of a power supply (1) having one electrode grounded, In a welding machine including a reactor (2), a shunt resistor (4), and a fan (5), a shunt resistor (4) is connected between a switching element (3) and ground, and the switching element (3) is connected. ) Is turned on, the current flowing through the shunt resistor (4) is detected, and when the detected current flows over a predetermined current value, the fan (5) is driven and the detected current flows over a predetermined time. A fan drive circuit (9) for turning off the drive of the fan (5) when the fan drive runs out;
(9) is the current pulse detected by the shunt resistor (4)
Generates an output when the size of is larger than a predetermined size
And the comparator that is set
A first signal for outputting a signal for driving the fan (5);
Flip-flop circuit and first flip-flop circuit
Transistor that receives the output of and rotates the fan (5)
Is set by the output of the comparator
Second flip-flop reset after time T1
Circuit and the set state of the first flip-flop circuit
And the period of the reset state of the second flip-flop circuit
The clock signal of the clock circuit is
And an AND circuit for outputting a signal and a second flip-flop circuit
When the count value is cleared each time the road is reset,
Generates output when a predetermined count value is reached
Then, the first flip-flop circuit is reset and the first flip-flop circuit is reset.
The output of the flip-flop circuit of the fan
(5) Count to turn off the transistor that rotates
The drive of the fan (5) is controlled by the presence or absence of a welding current.

[0007]

FIG. 1 shows an embodiment of the present invention.
1 is a power supply, 2 is a reactor, 3 is a switching element,
Reference numeral 4 denotes a shunt resistor, 5 denotes a fan, 6 denotes a welded portion, 7 denotes a commutation diode, 8 denotes a noise removal amplifier, and 9 denotes a fan drive circuit.

A shunt resistor 4 is connected between a switching element (a transistor will be described as an example in the following embodiments) 3 and the ground. When the transistor 3 is turned on by a PWM control signal, the shunt resistor 4 is connected to the reactor 2. The flowing welding current flows through the shunt resistor 4. That is, when the transistor 3 is turned on, a welding current flows in the circuit of the power source (battery) 1, the reactor 2, the welding portion 6, the transistor 3, the shunt resistor 4, the ground and the power source 1, and the transistor 3 is turned on from the shunt resistor 4. The welding current at the time of occurrence is detected.

When the transistor 3 is turned off, a welding current flows in the circuits of the reactor 2, the welding portion 6, the commutation diode 7, and the reactor 2 due to the energy stored in the reactor 2, and the arc is extinguished in the welding portion 6. Is prevented.

As described above, a pulse having a wave height proportional to the magnitude of the welding current is generated in the shunt resistor 4 in accordance with the switching of the transistor 3. Using this pulse, the noise removal amplification unit 8 and the fan drive circuit 9 control the fan 5 as follows. Even when the main switch (not shown in FIG. 1) is turned on, the fan 5 does not rotate unless welding is started. When a certain time has elapsed after the end of welding, the fan 5 automatically stops.

FIG. 2 shows the configuration of an embodiment of the noise removal amplifier and the fan drive circuit. In the figure, reference numerals 3 to 5, 9 correspond to those in FIG. 1, 10 is an amplifier, 11 is a buffer amplifier, 12 is a comparator, 13 and 14 are flip-flop circuits, 15 is a counter, 16 is an AND circuit, 17 Is a clock circuit, 18 is a transistor, 19 is a diode, 20 to 22 are capacitors, 23 is a variable resistor, and 24 to 29 are resistors.

The operation of FIG. 2 will be described with reference to the time chart of FIG. As described above, a pulse proportional to the magnitude of the welding current is generated in the shunt resistor 4 in accordance with the switching of the transistor 3. After the noise component of this pulse is removed by the filter of the resistor 24 and the capacitor 20, the pulse of the welding current is appropriately amplified by the amplifier 10.

The welding current pulse input to the fan drive circuit 9 is supplied to a comparator 12 via a buffer amplifier 11.
, And is compared with a reference voltage of a rotation start current of the fan 5 set by the variable resistor 23.

When the welding current flowing through the shunt resistor 4 is equal to or greater than the rotation start current of the fan 5, the output of the comparator 12 sets the flip-flop circuits 13 and 14, respectively. The output Q of the flip-flop circuit 13 becomes H level by the setting of the flip-flop circuit 13, the transistor 18 is controlled to be turned on, and the fan 5 starts rotating. That is, even if a main switch (not shown) is turned on, the fan 5 is stopped, welding is started, and when the welding current is equal to or more than a predetermined value, the fan starts rotating.

When the flip-flop circuit 14 is set, the capacitor 21 is simultaneously charged via the resistor 27. When the charged voltage reaches the level K shown in FIG. 3, the flip-flop circuit 14 is reset. You.
That is, when the flip-flop circuit 14 is set by the output of the comparator 12, it is reset after T1.
Therefore, while a welding current equal to or greater than the rotation start current of the fan 5 set by the variable resistor 23 flows through the shunt resistor 4,
The flip-flop circuit 14 repeats set and reset. Therefore, the counter 15 counts the clock from the clock circuit 17 via the AND circuit 16 while the output Q bar of the flip-flop circuit 14 is at the H level, but the counter 15 is reset at the H level of the output Q of the flip-flop circuit 14. Thus, the counter 15 does not output a count-up signal.

However, if the welding is not restarted during the time T2 (T1 << T2) from the time when the welding is completed, the counter 15 is set to output a count-up signal. When the H level of the count-up signal is output from 15, the flip-flop circuit 13 is reset via a differentiating circuit of the capacitor 22 and the resistor 28. As a result, the transistor 18 is turned off, and the fan 5 stops. Since the fan 5 continues to rotate during T2 after the welding is completed, the transistor 3 for controlling the welding current can be sufficiently cooled.

On the other hand, if the welding is resumed within the time T2 after the welding is completed, the flip-flop circuit 14 is set by the output from the comparator 12, so that the counter 15 does not output the above-mentioned count-up signal. The counter 15 is reset. Therefore, the fan 5 keeps rotating.

[0018]

As described above, according to the present invention, the rotation of the fan is controlled based on the welding current flowing through the shunt resistor connected between the switching element and the ground. Even if the welding is started, the fan does not rotate unless welding is started, and even if the main switch is forgotten to be turned off after welding is completed, the fan automatically stops after a certain period of time. Can be.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the present invention.

FIG. 2 is a configuration of an embodiment of a noise removal amplification unit and a fan drive circuit.

FIG. 3 is a time chart of the fan drive circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Power supply 2 Reactor 3 Switching element (transistor) 4 Shunt resistor 5 Fan 6 Weld part 7 Commutation diode 8 Noise removal amplification part 9 Fan drive circuit

Claims (1)

(57) [Scope of request for utility model registration] A welding device comprising a switching element (3) for turning on and off a voltage of a power supply (1) having one electrode grounded, a reactor (2), a shunt resistor (4), and a fan (5). A shunt resistor (4) is connected between the switching element (3) and the earth, and the shunt resistor (4) is turned on when the switching element (3) is turned on.
The fan (5) is driven when the detected current flows over a predetermined current value.
A fan drive circuit (9) is provided for turning off the fan (5) when the detection current stops flowing for a predetermined time or more, and the fan drive circuit (9) is detected by a shunt resistor (4).
The magnitude of the current pulse to be
The comparator that generates the output and the output of the comparator
A signal to drive the fan (5)
A first flip-flop circuit for output and a first flip-flop circuit.
The fan (5) is rotated by receiving the output of the flip-flop circuit
When set by transistor and comparator output
Both are reset after T1 of the short time.
Of the flip-flop circuit and the first flip-flop circuit.
Reset state and resetting of the second flip-flop circuit.
Clock circuit with the gate common to the
And an AND circuit for outputting a second clock signal.
The count value is cleared every time the flip-flop circuit is reset.
And when it reaches the predetermined count value
Generate output and reset to first flip-flop circuit
To make the output of the first flip-flop circuit disappear
Turn off the transistor that rotates the fan (5)
A fan control device for a welding machine, comprising: a counter; and controlling the drive of a fan (5) according to the presence or absence of a welding current.