JPH0814553A - Combustion control method for combustion equipment equipped with co detecting sensor upon intermittent combustion and device therefor - Google Patents

Abstract

PURPOSE:To prevent the increase in generation of CO gas by starting combustion operation with an improved mode when the combustion operation is effected again within a waiting time after stopping combustion, in a combustion equipment wherein the improved mode combustion, improving the combustion into the direction of complete combustion when a CO detecting concentration exceeds a reference value, is effected. CONSTITUTION:The combustion operation control unit 21 of a hot-water supplier effects combustion with an improved mode, improving the condition of combustion, when the concentration of CO in exhaust gas, which is detected by a CO sensor 20, exceeds a reference value while effects the combustion operation with a normal mode when the concentration of CO is lower than the reference value. In this case, a control mode memory unit 22, storing a combustion operation mode before stopping combustion upon stopping the combustion, is provided. Upon stopping combustion, a time of elapse from the time of stopping the combustion is counted by a timer 23 and when hot-water resupplying operation is commanded in the combustion operation control unit 21 and the time of elapse from the time of stopping the combustion has not achieved the predetermined waiting time while the previous combustion is effected with the improved mode, the combustion operation is started with the improved mode.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion control method and apparatus for intermittent combustion in which combustion and combustion stop of a combustion device with a CO detection sensor are repeated within a short time.

[0002]

2. Description of the Related Art FIG. 5 shows a system configuration of a general water heater as a combustion device. In the figure, a water supply pipe 3 is connected to the inlet side of the heat exchanger 2, and the water supply pipe 3 has a water inflow thermistor 10 for detecting the water inflow temperature and a flow rate sensor 9 for detecting a water inflow rate. And are provided. The hot water supply pipe 4 is connected to the outlet side of the heat exchanger 2,
A hot water supply tap 1 is provided on the outlet side of the hot water supply pipe 4.
Further, the hot water supply pipe 4 is provided with a water amount control valve 16 as a flow rate control means whose valve opening amount is controlled by a gear motor, and a hot water thermistor 11 for detecting the hot water temperature.

Below the heat exchanger 2, a burner 7 as a combustion heating means, an igniter electrode 18 for igniting the burner 7,
A flame rod electrode 19 for detecting ignition and a combustion fan 5 for supplying / exhausting air are arranged, a gas nozzle 6 is arranged opposite to a gas inlet of the burner 7, and a gas pipe 8 leading to the gas nozzle 6 is provided with a gas. Gas proportional valve 13 that controls the supply amount by the valve opening amount, and gas solenoid valve 12 that opens and closes the pipeline.
And are installed.

This type of water heater is provided with a control device 14, and a remote controller 15 is connected to the control device 14. The remote controller 15 has buttons for instructing hot water supply operation and buttons for setting hot water temperature. A display unit or the like for the hot water supply set temperature is provided. Also, on the wall surface on the exhaust top side, C in the exhaust gas
A CO sensor (carbon monoxide gas sensor) 20 as a CO detection sensor for detecting the O concentration (carbon monoxide gas concentration) is provided, and the CO detection signal of this CO sensor 20 is applied to the control device 14.

The control device 14 is provided with a circuit for controlling the hot water supply combustion operation and a circuit for performing a CO safety operation. The control circuit for the hot water supply combustion operation controls the hot water supply operation of the water heater as follows. When the hot water tap 1 is opened, the flow rate sensor 9 detects the amount of water entering, and when the amount of water entering exceeds a certain level (more than the minimum operating flow rate), a signal from the flow rate sensor 9 is received,
The control device 14 rotates the combustion fan 5. Then, when the rotation of the combustion fan 5 enters a predetermined rotation region, the gas solenoid valve 12 and the gas proportional valve 13 are opened to supply the gas to the burner 7, and the ignition operation by the igniter electrode 18 is performed. When the flame rod electrode 19 detects the ignition of the gas, the control device 14 performs the feedforward control so that the hot water outlet temperature becomes the set temperature, the opening amount of the gas proportional valve 13 is changed, and the hot water temperature coming out of the heat exchanger 2 is changed. The combustion control is performed so that the temperature becomes a set temperature, and after the hot water temperature is stabilized, the combustion control is performed by the combined control of the feedforward control and the feedback control.

In this combustion control, the control device 14 is provided with a combustion control system of a normal mode and an improvement mode. In the normal mode, when the CO detection value obtained from the CO sensor 20 is lower than a predetermined reference value, the gas supply is performed by the opening control of the gas proportional valve 13 in accordance with the required heat quantity required to raise the incoming water temperature to the set temperature. The amount of the combustion fan 5 is controlled and the rotation of the combustion fan 5 is controlled so that the amount of air corresponding to the amount of gas is obtained. On the other hand, in the improvement mode, when the CO detection concentration detected by the CO sensor 20 exceeds the reference value, the rotation speed of the combustion fan 5 is increased by a predetermined amount in order to improve the combustion in the incomplete combustion state in the complete combustion direction. To increase the amount of combustion air and CO in exhaust gas
Combustion control is performed in the direction of decreasing the gas concentration.
As another operation of this improvement mode, there is also a control system in which the opening amount of the gas proportional valve 13 is reduced to reduce the gas supply amount to the burner 7 to reduce the CO generation concentration.

The circuit for CO safe operation of the control unit 14 is
When the detected CO concentration detected by the CO sensor 20 reaches a predetermined dangerous concentration, combustion is stopped, or the CO sensor 20 detects the CO at a predetermined sampling time.
The detection signal is sampled, and C is sampled at each sampling time.
The CO safety operation is performed in various signal processing modes such that combustion is stopped when the O detection value is accumulated and the accumulated value reaches a preset danger judgment set value.

FIG. 6 is a flowchart showing a specific example of the operation of the conventional water heater. When the operation switch of the appliance is turned on, the stop flag for judging the combustion stop is cleared to zero in step 101, The fan-up flag for judging the rotation up of the combustion fan 5 is cleared to zero. It should be noted that when the stop flag is zero, it indicates a command not to stop combustion, and when the flag is set to 1, it means a command to stop combustion. Further, when the fan-up flag is zero, it means an operation command for not performing the fan rotation-up, and when the fan-up flag is 1, it means a fan rotation-up command.

In step 102, it is judged whether or not running water is detected by the flow rate sensor 9. When no running water is detected, hot water supply combustion is stopped (hot water tap 1 is closed)
Therefore, both the stop flag and the fan-up flag are set to zero to prepare for the next hot water supply combustion. When it is judged in step 102 that the running water is on, it is judged in the next step 103 whether the stop flag is 1 or not. When the stop flag is set to 1, it means that the combustion is instructed. Therefore, the ignition is not performed and the combustion operation is stopped. On the other hand, when 1 is not set in the stop flag, that is, when the stop flag is zero, the operation proceeds to the next step 104.

In step 104, the fan-up flag is set to 1
Judge whether is standing or not. When the fan-up flag is set to 1, the improvement mode in step 105 is selected, and when the fan-up flag is not set to 1, the normal mode is selected. In the first operation when the operation switch is turned on, both the stop flag and the fan-up flag are cleared to zero in step 101,
The normal mode in step 106 is selected, and in step 107, the combustion operation in the normal mode is performed.

In step 108, the CO detection value of the CO sensor 20 is 3000 ppm or higher, which is a dangerous concentration, or 1500 ppm.
Determine whether it is less than m or within the range of 1500ppm and 3000ppm. The reference value that becomes the boundary between the normal mode and the improvement mode is
It is set to 1500ppm and the CO detection value is the standard value 1500pp.
If m or less, combustion operation is continued in the normal mode, and when the CO detection value is between 1500ppm and 3000ppm, the CO detection concentration exceeds the reference value 1500ppm. Is set to 1, and the combustion operation is performed by shifting from the normal mode to the improvement mode. When the detected CO concentration is 3000 ppm or higher, which is a dangerous concentration, the stop flag 1 is set in step 110, and the combustion is immediately stopped in step 111 to achieve CO safety.

[0012]

FIG. 4 shows an operating state of opening and closing (on / off) of the hot water tap 1 of the conventional water heater, a combustion operation state of the water heater, and CO detected by the CO sensor 20. The relationship between the detected values (CO values) is shown in a time chart. In the conventional device, as is clear from the operation of step 112 in FIG. 6, when the combustion operation of the hot water supply is stopped (when running water off is determined in step 102), both the stop flag and the fan-up flag are set to zero. Therefore, regardless of whether the combustion operation mode before the combustion stop was the normal mode or the improvement mode, the combustion operation is always started in the normal mode at the next combustion. The Rukoto.

Therefore, for example, as shown in FIG.
When the hot water tap 1 is used for intermittent combustion which is repeatedly opened and closed within a short period of time, this intermittent combustion is usually used for washing dishes in the kitchen or washing hair in the washroom. When using such intermittent combustion, for example, when the ventilation fan is turned when the water heater is installed indoors, or when the water heater is installed outdoors and backwind is blown to the exhaust side, etc. In some cases, the blown air amount (air amount) supplied from the combustion fan 5 to the burner 7 may be insufficient, and the CO detection value may reach the reference value.

In this case, as a result of switching from the normal mode to the improvement mode and carrying out the combustion operation, hot water supply and combustion are performed without any particular problem, but next, the hot water supply tap 1 is closed and the hot water supply tap is restarted within a short time. When 1 is opened and hot water is re-applied, is the ventilation fan still turned?
Alternatively, it is assumed that headwind continues to be blown, and if the combustion operation is started in the improvement mode,
Since the amount of air blown by the combustion fan 5 does not become insufficient, the CO concentration in the exhaust gas does not increase. However, as described above, the hot water supply combustion is always started in the normal mode when the hot water is re-exposed. Since the combustion is started in the incomplete combustion state from the beginning, the CO concentration in the exhaust gas may increase and may exceed the dangerous concentration. In this case, CO
There is a problem that the safety circuit operates and the combustion is immediately stopped, so that the water heater cannot be used continuously.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to stop combustion even in the intermittent combustion such as hot water supply although the combustion operation is performed in the improved mode. After that, when the combustion operation is restarted within a short time, the problem due to the increase of the CO concentration due to the combustion operation being performed from the beginning can be solved, and the intermittent combustion operation can be performed in a good combustion state. (EN) A combustion control method and device for intermittent combustion of a combustion device with a CO detection sensor that can be used.

[0016]

In order to achieve the above object, the present invention is constructed as follows. That is, in the method of the present invention, a CO detection sensor for detecting the CO concentration in the exhaust gas is provided on the exhaust side of the combustion device, and when the CO detected concentration exceeds a preset reference value, combustion is performed in the complete combustion direction. In a combustion control method in which combustion is performed in an improvement mode for improving, and combustion is performed in a normal mode when the detected CO concentration is lower than the reference value, the combustion control before the combustion stop is performed in the improvement mode after the combustion is stopped. Whether or not it is determined, while measuring the elapsed time from the time of combustion stop,
When the combustion control before the combustion is stopped is performed in the improvement mode and the re-combustion operation is performed before the given standby time has elapsed, the combustion operation is started in the improvement mode, and the combustion is performed after the standby time has elapsed. When the operation is performed, the combustion operation is started in the normal mode.

Further, the apparatus of the present invention is provided with a CO detection sensor for detecting the CO concentration in the exhaust gas on the exhaust side of the combustion equipment, and when the CO detected concentration exceeds a preset reference value, the complete combustion direction is set. In a combustion control device that performs combustion in an improvement mode for improving combustion and performs combustion in a normal mode when the detected CO concentration falls below the reference value, a control mode storage that stores the mode of combustion control before the combustion is stopped when the combustion is stopped. Section, time measuring means for measuring the elapsed time from the combustion stop, and whether the elapsed time from the combustion stop when a re-combustion operation is commanded after the combustion stop has passed a predetermined waiting time. If the combustion control mode before the standby time elapses and the combustion control mode before the combustion stop is the improvement mode, the combustion operation is started in the improvement mode. It is configured as characterized by having a combustion operation control unit to start the combustion operation in de.

[0018]

In the present invention having the above-described structure, when the CO detection concentration detected by the CO detection sensor exceeds the reference value during the combustion operation of the combustion equipment, the combustion operation is performed in the improvement mode, but after the combustion is stopped, the standby state is established. When the combustion operation is performed again within the time, incomplete combustion is avoided by starting the combustion operation in the improved mode, and at the start of intermittent combustion, the incomplete combustion prevents the CO gas from increasing in the exhaust gas. To prevent.

[0019]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same names as those in the conventional example are designated by the same reference numerals, and the duplicate description thereof will be omitted. The combustion apparatus with a CO detection sensor of the present embodiment is intended for the water heater shown in FIG. 5 as in the conventional example, and the CO sensor 20 for detecting the CO concentration in the exhaust gas is provided on the exhaust top side of the water heater. Further, the control device 14 is provided with a circuit for controlling combustion operation and a circuit for performing CO safety operation. A feature of the present embodiment is that the control device 14 is provided with means for controlling combustion characteristics favorably during intermittent use of the water heater. As shown in FIG. 1, this means includes a combustion operation control unit 21, a control mode storage unit 22,
The timer 23 is provided as a time measuring means.

When the combustion operation of the water heater is stopped, the control mode storage unit 22 determines whether the combustion operation was performed in the control mode of the combustion operation before the stop, that is, in the normal mode.
Alternatively, the control mode as to whether the combustion operation was performed in the improvement mode is stored. The timer 23 measures the elapsed time from the time when the hot water supply combustion operation is stopped, and adds a time-up signal to the combustion operation control unit 21 when a predetermined waiting time (for example, 5 minutes) has elapsed.

When the combustion operation of the hot water supply is instructed by the remote controller 15, the combustion operation control unit 21 calculates the required heat quantity for making the incoming water temperature the set temperature and obtains this required heat quantity, as in the conventional example. After controlling the opening amount of the gas proportional valve 13 and controlling the rotation of the combustion fan 5, the feedforward control is performed when the burner 7 is ignited, and after the hot water temperature stabilizes, the combustion operation is performed by using both feedforward and feedback. To control.

Further, when the hot water heater is used for intermittent combustion, the combustion operation control unit 21 operates the timer 23 to measure the elapsed time from the stop of combustion, while the remote controller 15 is used. From the above, when the combustion operation of the re-hot water is commanded, it is determined from the time measured by the timer 23 whether or not a predetermined waiting time (for example, 5 minutes) has elapsed since the combustion was stopped, and the control mode is stored. The control mode stored in the unit 22 is read out. And the elapsed time from the stop of hot water supply combustion has not passed the standby time, and
Only when the previous combustion operation was performed in the improvement mode, the re-hot water combustion operation is started in the improvement mode, and in other cases, the re-hot water combustion operation is started in the normal mode.

FIG. 2 is a flow chart showing the operation of the hot water supply intermittent operation characteristic of this embodiment. The same operation parts as those in the flow chart of FIG. 6 showing the operation of the conventional example are designated by the same step numbers, The duplicate description will be omitted. A characteristic of the operation of the present embodiment is that the step operation of SP1 of timer clear is added between steps 102 and 103, and when the flow-on signal is not judged by the flow rate detection signal of the flow rate sensor 9 in step 102, that is, The operation unique to steps SP2 to SP5 is added when the hot water tap 1 is closed.

That is, the operation switch is turned on, the combustion operation is performed, and the CO detection value of the CO sensor 20 becomes the reference value.
Exceeds 1500ppm and does not reach the dangerous concentration of 3000ppm 1500 ~
When it is within 3000 ppm, the combustion operation is performed in the improved mode as in the conventional example, the fan-up flag is set to 1 in step 109, and this is stored in the storage mode control unit 22. Then, when it is determined in step 102 that the combustion stop with running water off is determined, the stop flag is set to zero in step SP2, the timer 23 is started in step SP3, and the elapsed time from the combustion stop is measured.

Next, in step SP4, it is determined whether or not a waiting time (for example, 5 minutes) given in advance has elapsed. If it is confirmed in step 102 that running water is on, that is, re-hot water is confirmed before the waiting time has elapsed, the timer is cleared in step SP1 and it is determined in step 103 whether 1 is set in the stop flag. In this case, since the stop flag is set to zero in step SP2,
In the next step 104, it is determined whether the fan-up flag is 1. In this case, if the combustion was performed in the improvement mode in the previous combustion, the fan-up flag 1 is stored in the control mode storage unit 22, so step 105
At step 107, the improvement mode is always selected, and in this improvement mode, the re-hot water is burned.

As described above, in the present embodiment, when the combustion operation is performed in the improvement mode as the control mode before the combustion is stopped, the improvement mode is always selected when the combustion operation of the re-hot water is performed within the waiting time. Then, the combustion operation of the re-outflow hot water is started in the improvement mode.

The fact that the previous combustion operation mode was performed in the improvement mode means that, for example, in an indoor water heater, it is assumed that the combustion operation is performed with the ventilation fan turned. It is assumed that the ventilating fan is continuously turned when the hot water is re-extracted within a short time during the standby time. Therefore, even if the ventilation fan is turned on, sufficient air is supplied by rotating the fan up, so incomplete combustion is avoided and combustion of the re-outflow hot water is performed under good combustion conditions. Becomes

FIG. 3 shows the relationship between the operating state of the hot water tap 1 and the combustion operating state of the water heater and the CO detection value (CO value) detected by the CO sensor 20 in this embodiment. As is apparent, when the detected CO value reaches the reference value and the combustion operation is performed in the improvement mode, the combustion operation is performed in the improvement mode when the hot water is again tapped within the next standby time, so that the CO in the exhaust gas is reduced. The concentration becomes a value smaller than the reference value, and the re-outflow operation is performed in the complete combustion state.
This effect is clear by comparing with the conventional example of FIG. In the conventional example, the CO concentration reaches a dangerous set value by starting in the normal mode at the time of re-releasing hot water, the CO safety circuit operates, combustion is stopped, and there is a problem that the water heater cannot be used. In this embodiment, this problem can be reliably prevented.

Further, in this embodiment, when the hot water is again discharged within the waiting time, that is, when it is judged in the step 102 that running water is turned on, the timer 23 is cleared in the next step SP1. Therefore, the timer 23
This prevents the combustion operation state in the improvement mode from suddenly switching to the combustion operation in the normal mode during combustion. That is, if the timer is not cleared at step SP1, even if the re-hot water is commanded within the waiting time and the combustion operation is started in the improvement mode, if the operation of the timer 23 from step SP3 is continued, it is improved. During the combustion operation in the mode, the measurement time of timer 23 reaches the standby time,
At this time, the fan-up flag is cleared to zero in step SP5, which causes a problem that the control mode is suddenly switched from the improvement mode to the normal mode.
In this embodiment, since the timer clear operation is inserted in step SP1, such a problem can be surely prevented.

In this embodiment, the fan-up flag is cleared to zero in step SP5 when the elapsed time from the last stop of hot water supply combustion exceeds the standby time. Therefore, in the next combustion operation, the normal mode is set. At this point, combustion operation will be started. When the standby time has been exceeded since the last time the hot water was stopped, for example, it is determined that the ventilation fan has been turned off and the ventilation fan has also been stopped.
Also, in the outdoor water heater, it is determined that the backwind has already stopped even when the backwind is blowing on the exhaust side after the waiting time, and the next combustion operation is performed in the normal mode. It will be.

In the combustion operation of the improvement mode, the combustion state in which the rotation of the combustion fan 5 is increased becomes a state in which the thermal efficiency is slightly lowered, and the gas proportional valve 13 is throttled in order to improve the combustion performance in the complete combustion direction. In the improved mode control method for reducing the gas supply amount to the burner 7, the combustion capacity decreases as the gas supply amount decreases, and the hot water flow rate is reduced accordingly. When both supply amount reduction methods are used, thermal efficiency and combustion capacity will decrease, and operation in these improved modes is an emergency combustion measure that avoids temporary deterioration of combustion conditions such as turning the ventilation fan. And when the elapsed time exceeds the standby time,
By eliminating this temporary measure, the combustion operation is started in the original normal mode.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in the above embodiment, the CO detection sensor is composed of the CO sensor 20,
Although the CO concentration in the exhaust gas is directly detected, for example, the CO detection sensor is configured by another sensor such as an O ₂ sensor or a CO ₂ sensor to indirectly detect the CO concentration in the exhaust gas. You may do it.

Further, in the above embodiment, the hot water supply device was described as an example of the combustion device. Etc. are applied to various other combustion devices that use gas or oil as fuel.

[0034]

As described above, according to the present invention, at the time of intermittent combustion of the combustion equipment, when the combustion before the combustion stop is performed in the improvement mode,
When the re-combustion operation is performed again within the given standby time, it is configured to start the combustion operation in the improvement mode without starting the combustion operation in the normal mode. Since the combustion operation is started in a state close to combustion, it is possible to avoid the combustion deterioration state in which the CO gas increases during re-combustion, and it is possible to perform the intermittent combustion operation with good combustion performance.

In the conventional example, even if the combustion operation is performed in the improvement mode before the combustion is stopped, the combustion operation is performed in the normal mode at the time of re-combustion, so that the CO concentration increases due to incomplete combustion, and the CO safety circuit However, in the present invention, if the previous combustion operation was performed in the improvement mode, the re-combustion operation is performed within a short time within the standby time. When it is performed, the combustion operation is always started in the improvement mode, and the combustion is performed in the complete combustion state. Therefore, the CO concentration in the exhaust gas does not abnormally increase and the CO safety circuit does not stop and the combustion operation stops. Therefore, it becomes possible to surely prevent the above-mentioned conventional problems.

[Brief description of drawings]

FIG. 1 is a block diagram of a main configuration showing an embodiment of the present invention.

FIG. 2 is a flow chart showing the operation of the embodiment.

FIG. 3 is a time chart of the operating state of the embodiment.

FIG. 4 is a time chart of an operation state of a conventional example.

FIG. 5 is a system diagram of a general water heater as a combustion device.

FIG. 6 is a flowchart showing an operation of the conventional water heater.

[Explanation of symbols]

 1 Hot Water Heater 5 Combustion Fan 14 Control Device 20 CO Sensor 21 Combustion Operation Control Unit 22 Control Mode Storage Unit 23 Timer

Claims (2)

[Claims] 1. A CO detection sensor for detecting the CO concentration in exhaust gas is provided on the exhaust side of a combustion device, and when the CO detected concentration exceeds a preset reference value, combustion is improved in the complete combustion direction. In the combustion control method of performing combustion in the improvement mode and performing combustion in the normal mode when the detected CO concentration falls below the reference value, whether or not the combustion control before the combustion stop was performed in the improvement mode after the combustion was stopped. On the other hand, while measuring the elapsed time from the stop of combustion,
When the combustion control before the combustion is stopped is performed in the improvement mode and the re-combustion operation is performed before the given standby time has elapsed, the combustion operation is started in the improvement mode, and the combustion is performed after the standby time has elapsed. A combustion control method for intermittent combustion of a combustion device with a CO detection sensor, which starts combustion operation in a normal mode when the operation is performed. 2. An improvement mode in which a CO detection sensor for detecting the CO concentration in the exhaust gas is provided on the exhaust side of the combustion equipment, and when the CO detected concentration exceeds a preset reference value, combustion is improved in the complete combustion direction. In a combustion control device for performing combustion in a normal mode when the detected CO concentration falls below the reference value, a control mode storage unit that stores a combustion control mode before the combustion is stopped when the combustion is stopped; A time measuring means for measuring the elapsed time from time, and when the re-combustion operation is commanded after the combustion stop, it is determined whether or not the elapsed time from the combustion stop has passed a predetermined waiting time, If the combustion control mode before the waiting time has elapsed and before the combustion is stopped is the improvement mode, the combustion operation is started in the improvement mode, otherwise the combustion operation is started in the normal mode. Combustion control device for intermittent combustion of a combustion device with a CO detection sensor having a combustion operation control unit.