JPH089609A - Engine-driven arc welding machine - Google Patents

Abstract

PURPOSE:To reduce the fuel and lubricant consumption of an engine-driven arc welding machine and improve the durability and reduce the noise of the engine used for the machine by continuously changing the welding output of the machine by controlling the phase of a thyristor and rotation of the engine by switching rectifier circuits and changing the rotating speed of the engine in accordance with the magnitude of the welding output. CONSTITUTION:Before starting welding work, the magnitude of the welding output of an engine-driven arc welding machine is checked in accordance with an object to be welded and, when an estimated welding output is large, thyristors SCR1, SCR2, and SCR3 are switched off through phase adjustment and a rectifier circuit composed of rectifiers D1, D2, and D3 is set to a half-wave rectifier circuit. Then the engine of the welding machine is rotated at a high speed and the magnetic flux is increased by making the current directions through armature windings a, b, and c coincident with that through a field winding (f) so as to increase the welding output of the welding machine. When the estimated welding output is small, on the other hand, the thyristors SCR1, SCR2, and SCR3 are switched on through phase adjustment and a full-wave rectifier circuit is formed and, at the same time, the engine is rotated at a low speed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine-driven arc welder in which the engine speed is adjusted according to the output required during welding.

[0002]

2. Description of the Related Art In a conventional engine-driven arc welding machine, the generator output is always maximized and rotated at a usable rotation speed. That is, the engine speed was kept at high speed regardless of the welding load.

[0003]

In the case of the above-mentioned conventional device,
The engine speed remains high regardless of the load. This means that the engine is rotating at a high speed even though the load is light and the engine output has a margin. Therefore, in addition to increasing fuel consumption and lubricating oil consumption, the amount of noise also increases. Further, as a result of these, deterioration of engine durability was unavoidable.

To solve the above problems, the generator must be made large in order to generate a sufficient output voltage at low speed, and a large capacity reactor is required to maintain sufficient welding characteristics. Need. Therefore, in order to satisfy these conditions, the price becomes high, and it is the current situation that it has not been put into practical use.

The present invention has been made in order to solve the above problems, and provides an engine-driven arc welding machine which suppresses fuel consumption and lubricating oil consumption, and has improved engine durability and reduced noise. Is intended.

[0006]

The engine-driven arc welding machine according to the first aspect of the present invention comprises a stator having an armature winding and a field winding, and an inductor having salient poles. In an engine-driven arc welder equipped with
A rectifier and a thyristor are used to connect a bridge-type rectifier circuit to the output end of the generator so that the direction of current supplied to the field winding and the direction of current flowing to the armature winding match when the thyristor is not conducting. The armature winding is connected to the switch, the rectifier circuit is switched according to the magnitude of the welding output, the engine speed is changed, and the welding output is continuously changed by the phase control of the thyristor and the engine speed control. .

In the engine-driven arc welder according to [Claim 2] of the present invention, in [Claim 1], when the welding output is large, the thyristor is phase-controlled so as to be non-conducting and the rectifier circuit is half-wave rectified. When the engine rotation speed is high and the welding output is small, the thyristor is phase-controlled to full conduction so that the rectification circuit is a full-wave rectification circuit and the engine rotation speed is low.

[0008]

First, the magnitude of the welding output is examined according to the object to be welded prior to the work. If the welding output is high, the thyristor is turned off and the rectifier circuit is a half-wave rectifier circuit, and the engine is set to high speed. On the other hand, if the welding output is small, turn on the thyristor and make the rectifier circuit a full-wave rectifier circuit.
Set engine to low speed.

[0009]

Embodiments will be described below with reference to the drawings. Figure 1
FIG. 1 is a configuration diagram of an embodiment of an engine-driven arc welding machine according to [Claim 1] of the present invention, which is shown as a sectional view. Figure 1
1 denotes a generator main body, and has a stator 2 and a rotor 3, and in this case, it is an example of a 4-pole 3-phase inductor type generator. As shown in the drawing, the inner peripheral surface of the stator has 12 grooves (m1 to m12) at equal intervals, and 12 armature windings (a1 to a4, b1 to b4) are provided in these grooves. , C1 to c
4) and four field windings (f1 to f4). Further, the rotor 3 is divided into four salient pole portions (31 to 34).
Consists of

FIG. 2 is a main control circuit diagram of the welding power source according to the present invention. The armature winding a in FIG. 2 is the armature winding a1. a2, a3, and a4 are connected in parallel or in series, and the same applies to the other armature windings b and c. That is, the windings in FIG. 2 correspond to the armature windings a1 to a4, b1 to b4, c1 to c4 in FIG. 1, respectively. Similarly, the field winding f is also the field winding f shown in FIG.
1, f2, f3 and f4 are connected in series.

Reference numeral B denotes a DC power supply for supplying a DC current to the field winding f. D1, D2, D3, D4
Is a rectifier, of which D1, D2, D3 are connected between each armature winding a, b, c and the output terminal 4, and D4 is another output terminal 5 and each armature winding a, Connect to the connection point (neutral point) of b and c. SCR1, SCR2, SCR3 are thyristors, and the other output terminal 5 and each armature winding a, b,
connected to c respectively.

Next, the operation will be described. From the no-load state (a state in which no load is connected between the output terminals 4 and 5). First, each thyristor SCR1, SCR2, SCR3 is made into a non-conducting state by phase adjustment in advance, and the engine is rotated at high speed. In this case, each armature winding a, b,
It becomes a half-wave rectifier circuit in which rectifiers D1, D2, D3 are connected to c. Therefore, the output voltage waveforms at the output terminals 4 and 5 are as shown in FIG.

Next, each thyristor SCR1. SCR2, S
The phase of CR3 is adjusted in advance so as to be in the fully conductive state, and the engine is rotated at a low speed (about half of the high speed rotation). In this case, the circuit is a full-wave rectifier circuit because all the rectifiers D1, D2, D3 and all the thyristors SCR1, SCR2, SCR3 are in a live (functioning) state. The voltage generated in each armature winding is about half that at high speed, but the output voltage waveforms at the output terminals 4 and 5 are as shown in FIG. 3C, and the average output voltage is as shown in FIG. ) Is almost the same as the case.

Next, each thyristor SCR1, SCR2, S
The phase of CR3 is adjusted in advance to halve the conduction angle, and the engine is rotated at medium speed (intermediate between high speed rotation and low speed rotation). In this case, the circuit is a half-wave rectifier circuit when the thyristor group is non-conductive and a full-wave rectifier circuit when conductive. The output voltage waveforms at the output terminals 4 and 5 are as shown in FIG. 3 (B), and the average output voltage is almost the same as in the case of FIGS. 3 (A) and 3 (C).

From the above, it can be understood that if the operating conditions of each thyristor are settled as described above, no matter whether the engine rotation is high speed, medium speed or low speed,
That is, the no-load voltage at the output terminal is almost unchanged. Moreover, in the case of general thyristor control, the output voltage may be zero depending on the phase angle, but in the present invention, it is the fact that the voltage is not interrupted, which is optimal as an arc welding power source.

Next, a load state (a state in which a load is connected to the output terminals 4 and 5) will be described. Similar to the above, each thyristor SC
The phases of R1, SCR2, and SCR3 are previously adjusted to be non-conducting, and the engine is rotated at high speed. In this case, paying attention to the armature winding a, the current flowing through it is the rectifier D1.
→ output terminal 4 → load → output terminal 5 → rectifier D4, but not in the opposite direction. That is, in this case, the armature winding a
Since the current direction of the field winding is the same as that of the field winding f,
It exerts a magnetizing effect to increase the output.

The same applies to the other armature windings b and c. FIG. 4 is a magnetic flux change diagram under load, and is shown corresponding to a state where the stator is expanded. FIG. 4 (A) is a relationship diagram between the magnetic flux φ and the induced voltage when the armature winding a is unloaded, and FIG.
FIG. 4B is a change diagram of the magnetic flux due to the armature reaction of the armature winding a, and FIG. 4C is a change diagram of the magnetic flux under load.
As shown in FIG. 4 (C), the magnetic flux under load is the sum of the magnetic flux of (A) and the magnetic flux of (B), which is larger than the magnetic flux of only (A). Recognize.

Next, each thyristor SCR1, SCR2, S
The phase of CR3 is adjusted in advance so that it is in the full conduction state, and the engine is rotated at a low speed. In this case, the circuit is a three-phase full-wave rectifier circuit. Therefore, an alternating current flows through each armature winding. FIG. 5 (A) is a relationship diagram between the magnetic flux φ and the induced voltage of the armature winding a when there is no load, FIG. 5 (B) is a change diagram of the magnetic flux due to the armature reaction of the armature winding a, and FIG. C) is a change diagram of magnetic flux under load. As shown in FIG. 5 (C), there is a portion that is the sum of the magnetic fluxes of (A) and (B) and a portion that is the difference, and as a result, it can be seen that there is no great difference from the magnetic flux shown in (A).

From the above, it can be understood that the welding output can be adjusted by selecting the output circuit and the engine speed according to the magnitude of the load. In this case, since the magnitude of the welding output can be known before the work depending on the object to be welded, the change of the output circuit and the setting of the engine speed may be settled in advance by a human system.

[0020]

As described above, according to the present invention, by selectively changing the welding output circuit and the engine speed in accordance with the object to be welded, the magnetizing action is provided during high speed rotation of the engine during welding. Since the welding output is increased and the welding output is not increased when the engine is rotating at a low speed, not only the welding output can be adjusted, but also the effects listed below are exhibited. (1) The no-load voltage at the output terminal hardly changes when the engine speed is high, medium, or low. (2) Since the output is not interrupted, stable arc welding can be performed. (3) Compact, lightweight and inexpensive. (4) Since the engine speed can be changed and used, the durability of the engine is improved. (5) Noise is reduced due to the above. (6) Fuel consumption and lubricating oil consumption can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment of an engine-driven arc welding machine according to [Claim 1] of the present invention, and is shown as a cross-sectional view of a generator.

FIG. 2 is a view showing a used portion of a welding power supply circuit.

FIG. 3 is a change diagram of a no-load voltage when the welding machine has no load.

FIG. 4 is a magnetic flux change diagram when the welding output is large.

FIG. 5 is a magnetic flux change diagram when the welding output is small.

[Description of symbols] 1 generator main body 2 stator 3 rotor 31 to 34 salient pole portions a1 to a4, b1 to b4, c1 to c4 armature windings f1 to f4 field windings m1 to m12 grooves

Claims (2)

[Claims] 1. An engine-driven arc welding machine equipped with a stator having an armature winding and a field winding wound around it, and a rotor composed of an inductor having salient poles, wherein the output end of the generator is Connect a rectifier circuit with a bridge structure using a rectifier and a thyristor, and connect the armature winding so that the direction of the current supplied to the field winding and the direction of the current flowing to the armature winding match when the thyristor is not conducting. Then, the rectifier circuit is switched according to the magnitude of the welding output, the engine speed is changed, and the welding output is continuously changed by the phase control of the thyristor and the engine speed control. . 2. When the welding output is high, the thyristor is phase-controlled so as to be non-conducting so that the rectifier circuit is a half-wave rectifier circuit, the engine rotation speed is high, and when the welding output is low, the thyristor is fully operated. 2. The engine-driven arc welding machine according to claim 1, wherein the rectifier circuit is a full-wave rectifier circuit by controlling the phase of conduction to reduce the engine speed.