JP2004239576A - Igniter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To propose an ignitor structure, especially for a power source synchronous type ignitor used to ignite fuel for a gas or a petroleum combustor or a heater, and to provide such power source cycle synchronous type ignitor, which is compact in size and capable of obtaining high power. <P>SOLUTION: The ignitor performing oscillation in response to a commercial source cycle of a frequency f is provided with a triggering circuit, a voltage doubler circuit, and a switching circuit on the primary side of a transformer and a discharge electrode on the secondary side. The triggering circuit is provided with a condenser C3 and resistance R1. The condenser C3 and the resistance R1 are set at C3×R1<(1/4f). <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an igniter for igniting a fuel such as a gas or oil combustion device or a heating device, and more particularly to a power supply synchronous type igniter structure.
[0002]
[Prior art]
Conventionally, an igniter for fuel ignition uses a commercial power supply, has an oscillation circuit that oscillates in synchronization with the frequency of 50 Hz or 60 Hz, and boosts the voltage by a transformer, so that a voltage of about several kilovolts is applied to the secondary side of the transformer. A power supply synchronous igniter that generates a high voltage is known. There is also known a cycle-down type igniter that produces a frequency lower than that of the commercial power supply and discharges at, for example, 12.5 Hz. There is a cycle down type in which a voltage doubler circuit is added to increase the ignition energy. In general, the power-synchronous type has a large number of discharges (ignitions), so it takes into account the ignitability of flame-retardant fuel. Conversely, the periodic down type requires only a small number of ignitions, so it takes into account the suppression of ignition noise. Designed.
[0003]
That is, the power supply synchronous type is an igniter that discharges at the same frequency as that of the commercial power supply. For example, if the frequency of the power supply is 50 Hz, the igniter discharges once at 50 Hz = 1/20 mS, that is, once at 20 mS. It operates by using the oscillation of the power supply without having.
[0004]
The periodic down type discharges at a frequency lower than the frequency of the commercial power supply. For example, if the discharge is performed at 12.5 Hz when the frequency of the power supply is 50 Hz, the discharge is performed once every four cycles of the power supply. The discharge cycle at that time is 80 mS, and discharge is performed once every 80 mS. That is, an igniter having a timer circuit or an oscillating circuit having a frequency lower than the frequency of the commercial power supply. Some periodic down types use a voltage doubler rectifier circuit to increase discharge energy. .
[0005]
[Problems to be solved by the invention]
As described above, when it is desired to increase the discharge energy without increasing the size of the igniter body, it is used to increase the input voltage to the transformer using a voltage doubler rectifier circuit. However, in the case of a power supply synchronous type igniter having a large number of ignitions, it is difficult to determine the trigger timing of the switching element that oscillates, and if ignition energy is not obtained due to a shift in ignition timing, a high voltage does not occur. I have. The present invention has been made in view of the above problems, and has as its object to provide a power supply cycle synchronization type igniter which is small and can obtain high output.
[0006]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention provides an igniter that oscillates in accordance with the frequency of a commercial power supply having a frequency f, including a trigger circuit, a voltage doubler circuit, and a switching circuit on a primary side of a transformer, and a secondary side of the transformer. Comprises a discharge electrode, the trigger circuit includes a capacitor C3 and a resistor R1, and the capacitor C3 and the resistor R1 are set to satisfy C3 × R1 <(１ ／ f).
[0007]
【Example】
FIG. 1 is a circuit diagram of an igniter according to an embodiment of the present invention. In FIG. 1, one end of a commercial power supply 10 is connected to one end of a transformer 50 from a trigger circuit 20 via a voltage doubler rectifier circuit 30, and the other end of the commercial power supply 10 is connected to a transformer 50 via a switching circuit 40 from a voltage doubler rectifier circuit. Discharge electrodes 60 are provided between the two ends of the secondary side of the transformer 50, which are connected to the other ends, respectively.
[0008]
The trigger circuit 20 is connected to a capacitor C3 connected to one end of the commercial power supply 10, diodes D4 and D3 connected to the capacitor C3, a resistor R4 connected to the cathode of the diode D4, and an anode of the diode D3. Resistor R1, a resistor R2 connected between the other ends of the resistors R4 and R1, and a transistor Q1 having a base connected to the other end of the resistor R1. The emitter of the transistor Q1 is connected to the other end of the resistor R4. The collector is connected to a switching circuit 40 described later. The emitter is connected to the other end of the commercial power supply 10.
[0009]
The voltage doubler rectifier circuit 30 is connected to a resistor R6 connected to one end of the commercial power supply 10, a capacitor C1 connected to the other end, and connected between the other end of the capacitor C1 and the other end of the resistor R6. A diode D2 connected in series with the resistor R6, a cathode connected to one end of the primary side of the transformer 50, and a capacitor C2 connected to the other end of the primary side of the transformer 50. D2 is provided so as to connect the cathode to the anode of the diode D1.
[0010]
The switching circuit 40 includes a switching element Q2 provided to connect an anode to one end of the transformer 50 and a cathode to the other end of the capacitor C2, and a gate of the switching element Q2 passes through a resistor R3 to connect the trigger circuit 20 to the trigger circuit 20. It is connected to the. Here, the switching element Q2 is constituted by a thyristor, and a resistor R5 is arranged between the cathode and the gate.
[0011]
Next, the operation of FIG. 1 will be described. The voltage doubler rectifier circuit 30 is a circuit that charges the capacitor C2 with a voltage doubler. When the other end of the commercial power supply 10 is positive, a base current flows through the transistor Q1 from the emitter of the transistor Q1 to the base, the resistor R1, the diode D3, the capacitor C3, and the one end of the commercial power supply 10, and the transistor Q1 turns on. As a result, the electric charge of the capacitor C1 flows through a path from the emitter to the collector of the transistor Q1, the resistor R3, the gate to the cathode of the switching element Q2, and the capacitor C1. This current causes a gate current to flow through the switching element Q2, turning on the switching element Q2. As a result, the electric charge of the capacitor C2 rapidly flows to the primary side of the transformer 50, and generates a high voltage on the secondary side thereof, so that discharge (ignition) occurs at the discharge electrode 60.
[0012]
Next, the role of the capacitor C3 will be described. FIG. 2 shows the voltage of the capacitor C2 of the present invention and the voltage waveform obtained from the commercial power supply 10. In FIG. 2, the waveform when the one end of the commercial power supply 10 is positive is defined as a plus. Here, when the capacitor C3 is not provided, in the waveform of FIG. 2, the transistor Q1 is turned on during the phase angle of 180 to 360 degrees, and the switching element Q2 is also triggered. However, since the charging of the capacitor C2 from the capacitor C1 has already started from 270 degrees, the switching element Q2 remains ON, the capacitor C2 is short-circuited by the switching element Q2, the capacitor C2 is not charged, and the high-voltage discharge stops. That is, it is necessary to limit the on state of the transistor Q1 to a range of 180 to 270 degrees, and this is performed by the capacitor C3. If the time constant determined by the capacitor C3 × the resistor R1 is sufficiently smaller than one-fourth of the 10 cycles of the commercial power supply, the current stops flowing through the resistor R1 when the charged voltage of the capacitor C3 becomes equal to the voltage of the power supply, The transistor Q1 turns off, and the gate current of the switching element Q2 disappears. At this time, since the anode current of the switching element Q2 has disappeared, the switching element Q2 is turned off, the capacitor C2 resumes charging after 270 degrees, repeats the oscillating operation thereafter, and performs high-voltage discharge by power supply synchronization. In consideration of the above conditions, the constant of the resistor R1 and the capacitor C3 can be realized by satisfying C3 × R1 <(＜ f), where f is the frequency of the commercial power supply. The diode D4 and the resistor R4 form a circuit for discharging the electric charge charged in the capacitor C3.
[0013]
【The invention's effect】
As described above, in the igniter of the power supply cycle synchronization type, it is possible to add a voltage doubler rectifier circuit by setting the optimum constants of the capacitor C3 and the resistor R1, and to provide a small-sized igniter with high output. did.
[Brief description of the drawings]
FIG. 1 is a circuit diagram of an igniter according to a first embodiment of the present invention. FIG. 2 is a diagram showing a waveform of charging a capacitor C2 of the present invention.
In the drawings, the same reference numerals indicate the same or corresponding parts.
DESCRIPTION OF SYMBOLS 10 Commercial power supply 20 Trigger circuit 30 Voltage doubler rectifier circuit 40 Switching circuit 50 Transformer 60 Discharge electrode

Claims (1)

An igniter that oscillates according to a cycle of a commercial power supply having a frequency f includes a trigger circuit, a voltage doubler circuit, and a switching circuit on a primary side of a transformer, a discharge electrode on a secondary side of the transformer, and a capacitor in the trigger circuit. An igniter comprising C3 and a resistor R1, wherein the capacitor C3 and the resistor R1 are set to C3 × R1 <(（f).

Images