JPH0442568B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a combustion control device that detects flame from a combustion means provided in a combustion chamber and controls combustion of the combustion means based on this flame detection signal. It is related to.

[Conventional technology]

Conventionally, in this type of combustion control device, an ultraviolet detection tube for detecting ultraviolet rays of a flame is used as a flame detection means for detecting a flame.

FIGS. 4 and 5 are longitudinal sectional views showing the ultraviolet detection tube. The ultraviolet detection tube shown in FIG. 4 is provided with a cathode 32 and an anode 33 in a glass tube 31 filled with a specific gas, and an external power source (not shown) is provided between the two electrodes.
Apply voltage from

With this voltage applied, when ultraviolet rays generated from a flame are irradiated, photoelectrons are emitted from the cathode 32, and these photoelectrons collide with gas molecules in the glass tube 31 and are ionized repeatedly. A discharge current flows between the anode 33 and the anode 33, and the presence of a flame is detected by this discharge current.

The ultraviolet detection tube shown in FIG. 5 has a cathode 32 and an anode 33 in a glass tube 31 filled with a specific gas.
mesh electrode plates 34 and 35 are provided on each of the cathode 32 and anode 33 so as to face each other, and a voltage is applied between the cathode 32 and anode 33, and the flame detection operation is performed as shown in FIG. It is the same as the ultraviolet detection tube.

[Problem to be solved by the invention]

Conventional combustion control devices are configured as described above, so if self-discharge is induced due to failure/deterioration of the ultraviolet detection tube, it is possible to detect that a flame exists even if the flame disappears and no ultraviolet light is detected. A signal was issued (simulated flame state), resulting in a malfunctioning mode.

In other words, since the ultraviolet detection tube cannot determine the self-discharge state, it cannot determine the state before it becomes a complete pseudo-flame, and it becomes a system that safely shuts down the combustion control device after the state becomes a complete pseudo-flame. Therefore, there was a problem that the timing of failure detection could not be predicted.

Furthermore, even if the burner equipment failed or the flame detector failed, the valve would simply be shut off. Therefore, there have been problems in that it is difficult to determine the cause of a failure and that maintenance requires a long time.

This invention was made to solve the above-mentioned problems, and its purpose is to provide a combustion control device that can easily distinguish the type of failure and easily determine the cause of the failure. shall be.

[Means to solve the problem]

The combustion control device according to the invention according to claim 1 includes a shutter disposed between the combustion means and the ultraviolet detection tube, a shutter control circuit that controls opening and closing of the shutter, and a shutter closing circuit that measures the closing time of the shutter. The apparatus includes a time measurement section and a first alarm determination section that compares the measurement time of the shutter closing time measurement section with the alarm setting time and issues an alarm output.

The invention according to claim 1 is the combustion control device according to claim 1, in which a shutter opening time measuring section for measuring the opening time of the shutter, and a comparison between the measured time of the shutter opening time measuring section and the alarm setting time are provided. It is equipped with a second alarm determination section that issues an alarm output.

[Effect]

The combustion control device according to the invention according to claim 1 includes:
By comparing the measurement time of the shutter closing time measuring section which measures the closing time of the shutter disposed between the combustion means and the ultraviolet detection tube and the alarm setting time in the first alarm judgment section and issuing an alarm output, A failure of the flame detection means can be detected separately from other failures, the cause of the failure can be easily determined, and maintenance can be improved.

Further, the invention as claimed in claim 2 is such that a second alarm judgment section compares the measurement time of the shutter open time measurement section and the alarm setting time and issues an alarm output, thereby detecting a failure of the ultraviolet detection tube or the combustion means, respectively. Since they are detected separately, maintenance is improved as in the invention described in claim 1.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings. In Fig. 1, 1 is a burner as a combustion means, 2 is an ultraviolet detection tube for detecting the flame 3, 4 is a shutter disposed between the burner and the ultraviolet detection tube 2, and 5 is the detection from the ultraviolet detection tube 2. This is a flame detection circuit that detects a flame by inputting a signal, and this flame detection circuit 5 includes a drive circuit 6 for the ultraviolet detector 2, a flame current detection circuit 7 that detects a flame current generated from the drive circuit, and the flame current. and a comparison circuit 8 that determines the presence or absence of flame.

9 is a combustion control means for controlling the burner 1 based on the output signal of the flame detection circuit 5; 10 is a shutter 4;
a shutter drive circuit for opening and closing; 11 a shutter closing time measuring section for measuring the closing time of the shutter 4;
2 is a first alarm determination section that compares the measured time of the shutter closing time measuring section 11 with the alarm setting time and issues an alarm output 13; 14 is a shutter opening time measuring section that measures the opening time of the shutter 4; and 15 is a shutter opening time measuring section. This is a second alarm determination section that compares the measurement time of the open time measurement section 14 and the alarm setting time and issues an alarm output 16.

FIG. 2 is a circuit diagram showing the configuration of the embodiment in more detail, with the same parts as in FIG. 1 being denoted by the same reference numerals. In FIG. 2, 17 is a drive coil for the shutter 4, and this drive coil 17 is connected to the AC power supply 1.
8. A light emitting diode 19b connected in series with the opening/closing contact 19a of the photocoupler 19 and controlling opening/closing of the opening/closing contact 19a is connected to the output end of the shutter drive circuit 10.

A circuit 20 that constitutes the shutter closing time measuring section 11 and the shutter opening time measuring section 14 is connected to the drive coil 17. This circuit 20 includes a diode D1, a resistor R1, a capacitor C1, and a capacitor C1 connected in series with the drive coil 17.
A series circuit of a resistor R2 connected in parallel to the light emitting diode D2 of the photocoupler 21, and a photocoupler 2 that receives the light from the light emitting diode D2 and becomes conductive.
1 phototransistor Tr1, a resistor R3 connected in series with this phototransistor Tr1,
The inverter IV1 is connected to the collector of the phototransistor Tr1.

The first alarm determination unit 12 includes an inverter IV2 that converts the output of the inverter IV1, a resistor R4,
A comparator 22 has the connection point P1 of the capacitor C2 connected to the non-inverting input terminal and the connection point P2 of the resistors R5 and R6 to the inverting input terminal, and the output terminal of this comparator 22 and one end of the resistor R7 are connected to the base. Transistor Tr2 in series with coil 23a of latch relay 23
and an opening/closing contact 23b of a latch relay 23 that issues an alarm output 13.

The second alarm determination unit 15 also includes a comparator 24 in which a connection point P3 between a resistor R8 and a capacitor C3 is connected to a non-inverting input terminal, and a connection point P4 between resistors R9 and R10 is connected to an inverting input terminal; A transistor Tr is connected to the base of the output terminal of the circuit 24 and one end of the resistor R11, and is connected in series with the coil 25a of the latch relay 25.
3, and an opening/closing contact 25b of a latch relay 25 that issues an alarm output 16.

Next, the operation will be explained based on the flowchart shown in FIG. During steady combustion (step ST-1), when the shutter 4 is opened, a flame detection signal is output from the flame detection circuit 5 based on the detection signal from the ultraviolet detection tube 2, and this flame detection signal is used to control the combustion control means 9.
It controls the burner 1 and operates the shutter drive circuit 10 via the shutter.

When the shutter drive circuit 10 operates, the drive coil 1 of the shutter 4 is connected via the photocoupler 19.
7 to close the shutter. Therefore, the detection signal from the ultraviolet detection tube 2 disappears, and the input to the combustion control means 9 and the shutter drive circuit 10 disappears, and the shutter drive circuit 10 is inoperative, and the drive coil 17 is no longer energized, and the shutter is activated. 4, and thereafter this series of shutter opening and closing operations is repeated at regular intervals. In this case, the opening/closing cycle of the shutter 4 is approximately several seconds.

Next, in steps ST-2 and ST-3, the shutter 4
When it is determined in step ST-2 that the shutter 4 is open or closed, the shutter open time is measured by the shutter open time measuring section 14, that is, the circuit 20 (step ST-5), and this measured time and the set time are are compared in step ST-5.

For example, if an abnormality occurs in the burner 1 and the flame 3 goes out during combustion, the flame 3 cannot be detected even if the shutter 4 is open, and the shutter 4 remains open out of the opening/closing cycle, and the second An alarm output 16 notifying burner abnormality is issued from the alarm determination section 15 (step ST-6).

On the other hand, when it is determined in step ST-3 that the shutter 4 is closed, the shutter closing time is measured by the shutter closing time measuring section 12, that is, the circuit 20 (step ST-7), and this measured time and the set time are divided into steps.
Compare with ST-8.

For example, if the ultraviolet detector 2 becomes abnormal and generates self-discharge, the detection signal continues even if the shutter 4 is closed, resulting in the same state as if the flame 3 were being detected. For this reason, the shutter 4 deviates from the opening/closing cycle and remains closed, causing the second
An alarm output 13 notifying an abnormality of the ultraviolet detection tube is issued from the alarm judgment unit 12 (step ST-
9).

Next, the measurement operation for opening and closing of the shutter 4 will be explained in detail. First, when the switching contact 19a is turned on, the drive coil 17 is excited to open the shutter, and at the same time, voltage is supplied to the circuit 20. Diode D1, resistor R1, capacitor C1
The voltage smoothed by is applied to the light emitting diode D2, and the phototransistor Tr1 is turned on.

Then, the output of the inverter IV1 becomes Hi (high) and starts charging the capacitor C3 via the resistor R8. Connection point P4 where the voltage at connection point P3 is determined by resistors R9 and R10 after a certain period of time has passed
When the bridge voltage exceeds , the output of the comparator 24 becomes Hi, the transistor Tr3 becomes conductive, and the relay 25 is activated to measure the shutter open time. On the other hand, the output of inverter IV2 is Lo
(low), and the charge in the capacitor C2 is discharged.

During the above shutter open time, if the shutter is closed before the potential at the connection point P3 exceeds the connection point P4, the phototransistor Tr1 is turned off and the output of the inverter IV1 becomes Lo. Therefore, the charge in the capacitor C3 is discharged and returns to its initial state.

On the other hand, the output of the inverter IV2 is Hi, and the capacitor C2 starts charging via the resistor R4. When a certain period of time has elapsed and the voltage at the connection point P1 exceeds the bridge voltage at the connection point P2 determined by the resistors R5 and R6, the comparator 2
The output of the transistor Tr2 is inverted to Hi, and the transistor Tr2 becomes conductive, activating the relay 23 and measuring the shutter closing time.

If the shutter is opened again before the voltage at the connection point P1 exceeds the voltage at the connection point P2, the operation returns to the above-described shutter open time measurement operation. Repeat the above operation and constantly measure the shutter open and close times.

〔Effect of the invention〕

As described above, according to the present invention, a shutter is provided between the combustion means and the ultraviolet detection tube, and abnormalities in the burner as the combustion means or the ultraviolet detection tube are distinguished and detected based on the opening or closing time of the shutter. Since the system is configured to notify, it is easy to determine the cause of the failure, and maintenance can be carried out in a short period of time.

Further, according to the present invention, since the shutter drive for opening and closing the shutter is controlled based on the output signal of the flame detection circuit, a failure of the flame detection circuit may cause the output signal to be An abnormality detection alarm is also issued when the output signal stops being output or when the output signal is continuously output due to self-discharge of the ultraviolet detection tube, making it extremely safe. It is.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing a combustion control device according to an embodiment of the present invention, FIG. 2 is a circuit diagram showing the combustion control device in detail, FIG. 3 is a flowchart explaining the operation, and FIGS. FIG. 5 is a longitudinal sectional view of the ultraviolet detection tube. 1 is a combustion means (burner), 2 is an ultraviolet detector,
4 is a shutter, 5 is a flame detection circuit, 9 is a combustion control means, 10 is a shutter drive circuit, 11 is a shutter closing time measuring section, 12 is a first alarm judgment section, 14 is a shutter opening time measuring section, and 15 is a shutter opening time measuring section. 2 alarm judgment section.

Claims (1)

[Claims] 1. An ultraviolet detection tube that detects a flame generated from a burner installed in a combustion chamber, a flame detection circuit that detects a flame by inputting a detection signal from the ultraviolet detection tube, and a flame detection circuit that detects a flame based on the output signal of the flame detection circuit. A combustion control device having a combustion control means for controlling a burner using a shutter, a shutter for opening and closing between the burner and the ultraviolet detection tube, and a shutter drive circuit for driving the shutter to open and close based on an output signal of the flame detection circuit. , a shutter closing time measurement unit that measures the shutter closing time; a first alarm determination unit that compares the measured time of the shutter closing time measurement unit with an alarm setting time and issues an alarm output; and the shutter opening time. a shutter opening time measuring section that measures the
A combustion control device comprising a second alarm determination section that compares the time measured by the shutter open time measurement section with the alarm setting time and issues an alarm output.