JPS58108328A - Detector for ignition and flame - Google Patents

Abstract

PURPOSE:To enable detection of even a flame whose rectifying action is weak, by a method wherein a time constant of a smoothin circuit is made larger than a cycle of voltage of an alternate current power source and a cycle generating a high voltage pulse of a pulse generating circuit is made larger than the time constant of the smoothing circuit. CONSTITUTION:When an ignition switch 11 is closed and charge of a condenser 7 becomes larger than a fixed value, a SAIDAC6 is electrified, the charge of the condenser 7 is discharged, its pulse voltage is boosted by a pulse transformer 5 and discharge is done between an electrode 3 and a burner 1. When a flame 5 is formed by igniting through this high voltage discharge, negative voltage of a condenser 15 is taken out by a smoothing circuit 18 and is detected by a flame detecting circuit 23. A time constant of the above smoothing circuit 18 is made into approximately 3-5 times of a cycle of a power source 12 and a time constant of a pulse generation cycle of a pulse generation circuit 4 is made into approximately 3-5 times of the time constant of the smoothing circuit 18. With this, even a flame whose rectifying action is weak can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a one-rod type ignition/flame detection device that uses both an ignition electrode and a flame detection electrode.

A conventional device of this kind will be explained with reference to FIG. 1. 1 is a conductive burner, 2 is a flame, and 3 is a single pole, which serves both as a discharge electrode and a flame detection electrode. 4 is a well-known pulse generation circuit;
An electrode 3 is connected to the secondary side of the pulse transformer 5. This pulse generating circuit is combined with a flame detection transformer 13 so that the pulse transformer 5&C generates a high voltage in phase opposite to the flame current, which will be described later. 6 is a SIDAC, 7 is a capacitor, 8 is a diode, and 9 is a resistor. 11 is a white switch, and 12 is a commercial AC power source. 13 is a flame detection transformer, 14 is a resistor, ]5 is a capacitor,
These 13, 14, and 15 tf'i constitute an AC power source applied to the flame 2. 16 is a honeyon lamp, ]8 is a low-pass filter circuit, and resistors 19, 20. capacitor 21
．． It consists of a 22 two-stage smoothing circuit. 23 is a well-known flame detection circuit that detects the negative voltage obtained by the flame rectification effect and determines the presence or absence of a flame. Sae is a comparison circuit, fin is an output terminal, and the ignition switch is turned off as soon as the level is reached. 26, 27, 28, and 29 are resistances.

30 is a DC power supply.

The operation of such a configuration will be explained. Large flame detection transformer 13
The secondary voltage is applied to the electrode 3 via a resistor 14, a capacitor 15, and a pulse transformer 5.

When the ignition switch 11 is turned on, the capacitor 7 is charged through the diode 8 and the resistor 9 in the positive half cycle, and when the charge exceeds a predetermined value, the sipe is activated.

The capacitor 7 is discharged, and the pulse voltage is stepped up by the pulse transformer 5, causing discharge between the electrode 3 and the burner 1. The discharge current at this time flows through a closed circuit of the secondary coil of the pulse transformer 50, the electrode 3, the Pana 1, and the discharged neon lamp 16. Neon lamp 16 is discharged, bypassing the high voltage. This pulse generating circuit 4
The generation frequency of pulses from the AC power source is 120 cycles (50
) is set to the same extent as h).

When ignition occurs due to this high voltage discharge and flame 2 is formed,
The alternating current applied by the flame detection transformer 13 is rectified by the flame 2f, and the direct current (hereinafter referred to as flame current) flows in the direction of the chamber frame 3 - flame 2 - burner 1. The direct current of this flame current charges the capacitor 15 so that the side facing the resistor 19 becomes negative. This DC negative voltage is taken out by the smoothing circuit 18 and detected by the flame detection circuit 23. The ignition switch 11 is immediately turned off when a flame is detected by the flame detection circuit. The time constant of the smoothing circuit [8] is set to about 10 times the period of the AC power source 12.

A specific example of the potential fluctuation of the output of the smoothing circuit 18 (indicated by A in FIG. 1) in the above series of operations will be explained with reference to FIG. 2. The horizontal axis in FIG. 2 indicates time.

When the ignition switch 11 is not turned on, there is no flame and no flame current is generated. Therefore, the current is smoothed by the smoothing circuit 18 and (0)■ is obtained. The divided potentials of resistors 26 and 270 are set to be larger than the divided potentials of resistors A and 4. Therefore, the negative input of the comparison circuit 24 is larger than the positive input, and the level HL appears at the output terminal 25.

When the ignition switch 11 is turned on at time t1, the voltage of the high voltage discharge is added, so the potential at the input terminal A increases by E.

If the flame is ignited at time 12, a large current will flow due to the rectification effect of the flame, and the potential at the input terminal A will rapidly drop by <E2 as shown by the broken line. ( ) Vl, the potential of the buying input of the comparator circuit 24 becomes smaller than the potential of the positive input, a ratio level is obtained at the output terminal station at time t3, and the ignition switch 11 is turned off.
do.

When the ignition switch 11 is turned off at time t3, the high voltage discharge disappears, so the potential at point A changes from (0)■ to E, (
V) becomes a low potential.

For reference, the broken line indicates the potential when the ignition switch 11 continues to be turned on until t4.

If the inflammation is extinguished at time ts, it returns to (0)■.

In this way, since the flame detection point is (-) Vl, E
2 > Et. Also, E, to E2
minus ()Vg must be less than (-)Vt. This E, Ifi is determined by the rectifying effect of the flame, and Vl is smaller for a burner with a smaller rectifying effect of the flame. Therefore, in a burner with a small rectification effect, (3
If V1 was considered fixed, flame detection was difficult.

The seventh object of the present invention is to provide a flame detection device that can stably detect a flame even if the rectifying effect of the flame 5 is weak.

The present invention makes it possible to detect even a flame with a weak rectifying effect by making the pulse period of the pulse generating circuit larger than the time constant of the smoothing circuit.

To explain the present invention in detail, the time constant of the smoothing circuit 18 is set to 3 to 2 ohms when the period of the AC illumination 12 is (50 seconds).
The time constant of the pulse generation period of the pulse generating circuit 4 is set to about 5 times (for example, about 80 m5), and the smoothing circuit 18
It is configured so that the time constant is about 3 to 5 times [(@Ege, about 300 m S darkness). The other configurations are the same as before.

The operation of this configuration will be explained with reference to FIG. FIG. 3 shows the potential change at the input terminal A point of the flame detection circuit 23.

When the ignition switch 11 is turned on at time t1, the potential at point A changes from 0 to E at intervals of the pulse generation cycle of the pulse generation circuit 4.
Go up one line.

If they ignite at the same time at time t2, the rectifying effect of the flame will lower the electric potential by E2, resulting in a potential of (, d4) of (0~E□)-E.Then, this lowered potential ((0-Ex) E
2) becomes (-)■, the output terminal 5 becomes Hi level at time t3 and the ignition switch 11 is turned OFF.
It will be FF.

When ignition switch 1] is turned off at time t3, the potential becomes (
-) Continue E2.

This shows the case where the ignition switch 11 is turned off at the point of broken line Fi *4. Therefore, the bottom (-
) ■2 is the same as (→E2.

As mentioned above, in order to detect flame 2, VC and El are 0 (
V) ~& (v)T Alf) "t', El
> El ti E2 > 0 (V) ~E, (V
)r ant, j-) teE2>0(V) tttd, and even a flame with a weak rectifying effect (& is small) can be detected.

As described above, in the present invention, the time constant of the smoothing circuit is set larger than the period of the voltage of the AC power source, and the period of generation of high voltage pulses of the pulse generating circuit is set larger than the time constant of the smoothing circuit. It is possible to detect flame even with a burner with a weak effect.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a conventional ignition/flame detection device, Fig. 2 is a diagram illustrating the potential fluctuation of the output of the smoothing circuit in Fig. 1, and Fig. 3
The figure is a diagram illustrating potential fluctuations in the output of the smoothing circuit of the ignition/flame detection device of the present invention. 1...Burner 2...Fire Flame 3...Electricity
Pole 4...Pulse generating circuit 5...Pulse transformer 11...Ignition switch 12...AC power supply
13...Flame extraction transformer 16...Neon tube 18...Smoothing circuit...Flame detection circuit

Claims (1)

[Claims] 1. Electrode, secondary side of the pulse transformer of the pulse generation circuit that generates high voltage pulses for ignition, capacitor, resistor, secondary side of the flame detection transformer. A voltage bypass circuit and a smoothing circuit are respectively provided in parallel with the series circuit on the secondary side of the capacitor, the resistor, and the flame detection transformer, and the output signal of the smoothing circuit is inputted to determine the presence or absence of a flame. In the ignition/flame detection device, the ignition/flame detection device is provided with a flame detection circuit that stops the generation of high voltage pulses by the pulse generation circuit when a flame is present, and inputs AC power to the pulse generation circuit and the flame detection transformer. The time constant of the smoothing circuit is set larger than the period of the voltage of the AC power source, and the period of generation of high voltage pulses of the pulse generating circuit is set larger than the time constant of the smoothing circuit. Flame detection device.