JPS62119326A - Igniting device - Google Patents

Abstract

PURPOSE:To prevent the malfunction of a microcomputer by constituting an igniting device of a kerosene fan heater or the like such that the device is ignited by the ignition of a thyristor, and, when a microcomputer detects zero crossing, the ignition signal to the thyristor is output through a non-contact switch. CONSTITUTION:A microcomputer 22a within a control circuit 22 detects whether or not a power supply waveform is a zero volt or not together with the closing operation switches 20 and 20a. When the zero volt of a power supply waveform is detected, an output is emitted to a point (d) and a thyristor 36 is turned ON. After the completion of recharging, outputting to the point (d) is repeated and thyristors are successively turned ON. By this construction, even when a noise is generated due to spark, since the power supply waveform is zero volt at the time when the noise is generated. The noise is difficult to enter into an AC power source circuit and thus occurrence of malfunction of the microcomputer 22a is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an ignition device for a combustion appliance such as a kerosene fan heater.

2. Description of the Related Art In general, combustion appliances such as oil fan heaters are ignited by an ignition device using a thyristor. Figure 4 shows a conventional general ignition system circuit diagram,
The AC power source 1 passes through the contact 3 of the relay 2 and forms a closed circuit with the point a, the diode 4, the limiting resistor 5, the pulse capacitor 6, the primary side 8.0 point of the step-up transformer 7, the diode 9, and the point d. ing. A thyristor 10 and a diode 11 with different polarities are connected in parallel between b and c, and a series circuit of a resistor 12 and a trigger element 13 is connected between point d and point 80 of the thyristor 10. It is. Note that a −
Resistors 14 and 15 are connected between points c and between points e and c. The diode 9, the resistors 12; 14; 15, and the trigger element 13 form a trigger circuit 10a of the thyristor 10. Also, the ground 16 of the secondary side 16 of the step-up transformer 7
Since high voltage is generated between the high voltage side 16a and the high voltage side 16b, the structure should be such that sufficient insulation can be ensured.

The operation of this circuit will be explained with reference to the characteristic diagram of FIG. 5. When a signal is applied to the coil side 17 of the relay 2 and the contact 3 is closed, an alternating current voltage is applied between points a and d. The waveform tal in FIG. 5 is the waveform between points a and d. First, during time 11 when point a is positive, capacitor 6 is charged, so the characteristic becomes +bl. Next, at t2 when point d is positive, charging is not performed (the bl characteristics become parallel, but from point d, resistor 12 - trigger element 13 -
Thyristor 10 Day 80 points - Cando point C - Resistance 14
- a voltage is applied between the trigger elements 13 in the order of four points,
Its characteristic is 101. Let the time at which the trigger voltage is reached be t3 in FIG. At this point, the thyristor 101 is turned on, so that the charge stored in the capacitor 6 is instantly discharged. Therefore, a voltage proportional to the turns ratio is generated on the secondary side of the transformer 7, and its waveform is fd +
The voltage becomes d+ and ignition occurs as v2.

Problems to be Solved by the Invention From the above configuration, (7) As is clear, in the conventional circuit, the phase during which the capacitor 6 is charged and the phase in which the trigger circuit 18 operates are reversed. Further, the triggering time is also t3, and the thyristor 10 becomes conductive after reaching the trigger voltage of the trigger element 1a. Therefore, the operation of the relay 12 and the trigger point are completely out of synchronization. Therefore, since the signal coming to the coil 17 of relay 2 is not synchronized with the operation of igniter 4, if contact 3 opens while the igniter is operating, the noise will continue to be input to the power, and contact 3 will open and close again. Noise may enter the power supply side due to rush current caused by the capacitor and the primary coil of the transformer 7.

Although not explicitly shown here, there is a microcomputer (hereinafter referred to as microcomputer) for combustion control on the power supply side.
If abnormal noise or pulses occur, this may cause erroneous ω1 operation or runaway.

The present invention has been made in view of these points, and is aimed at preventing malfunction of a microcomputer due to abnormal noise entering the power supply side.

The method to solve the problem is original F'! In order to solve the above problem, the ignition circuit is configured to fire a thyristor and discharge the charge stored in the capacitor to generate a spark via a step-up transformer, and the control circuit is configured to The groove is arranged so that when the provided microcomputer detects a zero cross, it outputs an ignition signal to the thyristor via the non-contact switch means.

Operation The IJI according to the present invention generates a spark when the voltage waveform of the AC power supply circuit is zero volts due to the above configuration. The noise generated at zero volts usually has very little effect on the AC power supply circuit, so the impact on the load connected to the AC power supply circuit via the DC constant voltage circuit, that is, the microcomputer, is less than that of conventional noise. It will be reduced to 11 points.

In addition, since the switch means for generating the spark is not mechanical, the switching means can be opened and closed.
No more 46 sounds mixed in.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 3.

In Fig. 1, 18 is an AC power supply, and its both ends a-b
Between the points, terminals ■ and ■ of the ignition circuit 19 and a zero-point operation switch 20 are connected. Further, a power transformer 21 is connected between points a and b, and a DC constant voltage circuit 23 of a control circuit 22 mainly composed of a microcomputer 22a is connected to this. The above control circuit controls the AC load group 24 such as oil field pumps and blower motors, and this AC load d
The Ij group 24 is connected between points a and c.

On the other hand, a light emitting diode 26 of a photocoupler 25 is connected to the DC constant voltage circuit 23, and a control circuit 2
A transistor 29 is connected via a resistor 30 between a resistor 27 and a resistor 28 between the output point d of No. 2 and the ground.

The ignition circuit 19 has a groove structure in which the diode 31, the resistor 32e, the capacitor 33, and the primary winding 35 of the step-up transformer 34 are connected in series to the terminal (2). A thyristor 36 and a diode 37 with reversed polarity are connected between e and 0, and a DC power supply circuit 38 is connected between 1 and 2. The above DC power supply circuit includes 38 diodes 39 and a resistor 40. At point f, a capacitor 41 is connected in series, and a resistor 42 is connected in parallel to the capacitor 41. Further, the phototransistor 26aH collector of the photocoupler 25 is connected to point f (■), and the rainbow is connected to the gate 8 point (■) of the thyristor 36. Note that the operation switch 20 is interlocked with a combustion start switch 20a of the control circuit 22.

In the above configuration, the operation of this circuit will be explained next. First, when AClooV is applied to the AC power supply 18, the DC constant voltage circuit 23 and the control circuit 22 start operating and are waiting for the start of operation. When the operation switches 20 and 20a are closed, the control circuit 22 operates the AC load group 24 to start silent burning.

On the other hand, the ignition device 19 starts charging the capacitor 33 when AC power is applied, and as it is, the thyristor 33 starts charging.
Waiting for 6 to turn on. The control circuit 22 is programmed so that the microcomputer 22a therein observes the power waveform from the power transformer 21, and when the terminal (2) side is positive, that is, at time t1. in FIG. t3...When the above is detected and +2, ta is entered (power supply voltage waveform ta,
The aim is to output an output to point d and turn on the thyristor 36 at the point when l exceeds zero volts.

That is, the processing procedure incorporated in the microcomputer 22aKm in the control circuit 22 is structured as shown in FIG. . . . That is, it is detected whether it is the charging completion time or not, and when the charging completion time is reached, it is detected in routine 22c whether the power supply waveform is zero volts or not. When this routine 22c detects zero volts of the power source Il type, the routine 22d outputs an output to point d, and the cycle of returning to the routine 22b again is repeated and the thyristor 36
are turned on one after another. On the other hand, the ignition circuit 19 turns on the capacitor 3 by turning on the thyristor 36.
3 is instantly discharged, and the step-up transformer 3
40 High voltage end f46a of secondary winding 46 and ground terminal 46
High pressure is generated between the (Waveform d) At this time, even if noise is generated due to the spark, the power waveform is zero volts when this noise occurs, so it does not enter the AC power circuit.
There will be no possibility of a malfunctioning. Further, since the start and stop of spark (ignition) are all performed by turning on the thyristor 36 to point d, which occurs at zero volts, there is no noise generated by opening and closing of mechanical switches.

By the way, if the microcomputer 22a of the control circuit 22 has a procedure for instantaneously outputting an output to point d and turning on the phototransistor 26a when the operation switches 20 and 20a are turned OFF, the process can be done by turning OFF the operation switches 20 and 20a. The thyristor 36 becomes conductive and the charge remaining in the capacitor 33 can be discharged, thereby improving reliability.

Effects of the Invention As described above, according to the ignition device of the present invention, since all control is performed at zero cross, noise generation factors are greatly reduced, and noise transmitted from the power supply line is extremely reduced. Furthermore, since the control is not performed by mechanical switching means such as relays, there are no contact elements, further reducing noise generation factors and increasing the service life. Therefore, the microcomputer on the control circuit side will not malfunction due to noise.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of an ignition device in an embodiment of the present invention;
Figure 2 is an explanatory diagram of the characteristics of the same circuit. Figure 3 is for explanation of operation.
0-chart, Figure 4 is a circuit diagram showing a conventional ignition system,
FIG. S is an explanatory diagram of the characteristics of the same circuit. 18... AC power supply, 19... Ignition circuit, 22
... Control circuit, 22a ... Microcomputer, 23 ... DC constant voltage circuit, 25 ...
... Non-contact switch means (photocoupler), 33...
・Capacitor, Nu... Step-up transformer, 36...
...thyristor. Name of agent: Patent attorney Toshio Nakao and 1 other person 2nd
Figure 5

Claims (1)

[Claims] The ignition circuit includes an ignition circuit connected to an AC power supply, and a control circuit connected to the AC power supply via a DC constant voltage circuit to operate the ignition circuit. The control circuit is configured to generate a spark via a step-up transformer by discharging the thyristor, and the control circuit sends an ignition signal to the thyristor via a non-contact switch when a microcomputer provided in the control circuit detects a zero cross. An ignition device configured to output