JPH0244122A - Combustion controller - Google Patents

Abstract

PURPOSE:To enable safe and secure ignition of a burner and prevent resonating sound from being generated in the beginning stage of ignition by changing the opening of a proportional valve to an opening different from an opening for slow ignition, immediately upon detection of light off of the burner by a light off detecting means, and maintaining the changed opening for a predetermined time. CONSTITUTION:When light off is detected by a frame rod 15, an output from a flame detecting circuit 38 is changed from a low level to a high level, and a signal inputted through a terminal 62 of an opening-changing circuit 60 is also changed accordingly, upon which an output from a comparator 61 is kept at a high level for a predetermined time, and a transistor 76 is turned ON for a predetermined time. Therefore, a control voltage impressed on a terminal 51 of a proportional valve-driving circuit 50 by a microcomputer 40 is lowered, and a current passed to a proportional valve 23 is decreased, so that the opening of the valve 23 is made to be smaller than an opening for slow ignition, for a predetermined time for which the circuit 60 is operated. As a result, the quantity of a fuel supplied is reduced upon detection of the light off, whereby an air-fuel ratio responsible for the generation of resonating sound is changed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a combustion control system for controlling a combustion device in which a burner is disposed in a combustion chamber.

(-Prior Art) For example, in combustion equipment such as gas water heaters in which a burner is placed in the combustion chamber, resonance noise may be generated as a result of combustion.Therefore, measures must be taken to prevent resonance noise from occurring. Control the ratio of combustion air volume and gas image, or design the shape and size of the combustion volume case, exhaust port, air supply port, etc. that form the combustion chamber!

ing.

In addition, when igniting, in order to ensure safety and ignitability, the amount of fuel supplied for slow ignition is preset for each combustion device, and the current value of the proportional valve that adjusts the amount of fuel supplied is set in advance for each combustion device. is controlled to an ignition current value that provides the fuel supply amount for this slow ignition. After ignition, the ignition current value is continuously applied to the proportional valve for a predetermined period of time (generally one to several seconds) until the flame stabilizes.

[Problem to be solved by the invention] However, since the amount of fuel supplied for slow ignition is determined with emphasis on ignitability, it does not necessarily result in an air-fuel ratio with excellent flammability. If the amount of fuel supplied for slow ignition is determined by placing importance on performance, combustion may become unstable if combustion conditions differ due to outside air temperature or exhaust extension, and in that case, abnormalities such as resonance noise may occur. Sound is more likely to be generated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a combustion control device that can prevent resonance noise from occurring during ignition while ensuring reliability and safety of ignition.

[Means for Solving the Problems] The present invention provides a solenoid valve and a proportional valve in a fuel supply path that supplies fuel to a burner, and when the burner is ignited, the solenoid valve is opened and the proportional valve is opened. A combustion control device that controls a proportional valve to a slow ignition opening degree, and controls the opening degree of the proportional valve according to a set combustion amount after the ignition operation,
ignition detection means for detecting ignition of the burner; and opening degree changing means for changing the opening degree of the proportional valve; Changing the opening degree to a different one from the slow ignition opening degree,
The technical means is to maintain the changed opening degree for a predetermined period of time.

[Operation] In the present invention, when the burner is ignited, the solenoid valve is opened, and the proportional valve is controlled to a gentle ignition opening degree.

Therefore, when the burner is ignited by the zero ignition operation in which fuel is supplied to the burner according to the slow ignition opening, and the ignition is detected by the ignition detection means, the opening of the proportional valve is different from the slow ignition opening. The opening is changed to a different opening, and the proportional valve changes from a slow ignition opening that emphasizes ignitability to a different opening. Therefore, the amount of fuel supplied to the burner is changed from the amount of fuel supplied for slow ignition, which has unstable combustibility, to a different amount of fuel, for example, to an amount of fuel that has excellent combustibility.

The combustion state of the burner changes depending on the amount of fuel supplied, and is maintained for a predetermined period of time. After that, the opening degree of the proportional valve is controlled to the opening degree according to the set combustion amount. Combustion is performed with the amount of combustion.

[Effects of the Invention] In the present invention, at the time of ignition, the proportional valve is controlled to a gentle ignition opening degree, and an appropriate amount of fuel is supplied to the burner, so that the burner can be ignited reliably and safely. In addition, when ignition is detected, the fuel supply amount is changed from the supply amount for slow ignition, which has unstable combustibility, to a supply amount that provides stable combustion, for example, and the burner combusts accordingly. will be held. Therefore, combustion in the burner is no longer in an unstable combustibility state, so that abnormal noise such as resonance noise is not generated due to combustion.

Therefore, for example, in a combustion device that is designed so that resonance noise does not occur during steady combustion, if the proportional valve is continuously controlled to a gentle ignition opening in the initial stage of ignition when the combustion state is not stable after ignition is detected, resonance noise may be generated. Even in such a case, according to the present invention, the fuel supply amount is changed at the same time as the ignition is detected at the initial stage of ignition, so that resonance noise will not be generated after the ignition is detected.

Embodiments] Next, a combustion control device of the present invention will be described based on embodiments shown in the drawings.

A burner group 11 including a plurality of ribbon burners is provided in a combustion amount case 10 of the gas combustion type water heater 1 shown in FIG. A blower case 12 a is provided below the combustion amount case 10 and includes a blower 12 for supplying combustion air to the burner group 11 . A heat exchanger 13 is provided on one side of the combustion case 10, and water passing through the interior is heated by combustion heat from the burner group 11.

A sparker 14 for igniting the burner group 11 and a flame rod 15 for detecting ignition of the burner group 11 are provided near the burner group 11 in the combustion amount case 10. Furthermore, an exhaust port 2 for discharging combustion exhaust gas to the outside is provided on one side of the combustion amount case 10.

The burner group 11 is equipped with a nozzle pipe 16 for supplying fuel gas, and the nozzle pipe 16 has a plurality of nozzles 16 that eject fuel gas corresponding to each ribbon burner.
A is provided.

The fuel pipe 20 that supplies fuel gas to the nozzle pipe 16 includes, in order from the upstream side, a source solenoid valve 21 and a main solenoid valve 22 that allow the fuel gas to pass through when energized. Proportional valve 2 that adjusts the gas supplier
3 is provided.

A water supply pipe 17 that leads water from a water supply source (not shown) to the heat exchanger 13 includes, in order from the upstream side, an inlet water temperature thermistor 25 that detects the inlet water temperature, and a Mercury control valve 2G that adjusts the amount of hot water supply.
, a water flow sensor 27 for detecting the amount of hot water supplied is provided, and a hot water supply pipe 17a that guides the hot water flowing out from the heat exchanger 13 to a hot water supply port (not shown) is equipped with a hot water outlet sensor 27 for detecting the temperature of hot water supply.
Mr. 28 is provided.

As shown in the figure, the control device 30 includes a microcomputer 40 (hereinafter referred to as "microcomputer 40") equipped with an interface, and a control unit 1 operated by the user. '''1-ra 31 is provided, and the burner group 11 performs combustion in a predetermined sequence, and the combustion amount and hot water supply 1 are adjusted according to the set temperature of the controller 31.For this purpose, the control device 30 includes a , the following input/output circuits are provided.

The communication circuit 31a includes the controller 31 and the microcomputer 40.
Signals are exchanged between the two.

The water flow detection circuit 32 is connected to the water flow sensor 2'iT? When the number of generated pulses becomes equal to a predetermined number f:'-, reverse water is detected and a water flow signal is sent to the microcomputer 40.

The water temperature detection circuit 33 sends an incoming water temperature signal and an outgoing water temperature signal to the microcomputer 40, respectively, based on the resistance values (,;-:) of the incoming water temperature thermistor 25 and the outgoing water temperature thermistor 28.

The water valve circuit 34 is a circuit that energizes a geared motor provided to drive the Mercury control valve 26, and the opening degree of the water flow control valve 26 is detected by a potentiometer (not shown). .

The sub-power circuit 35 generates a high voltage from 1 to 14 and generates a sub-power 14.

The fan circuit 3G drives one unit of the blower 12 according to the control signal from the microcontroller 40, and also detects the rotational speed of the motor using a pole element and sends the rotational speed 4i4 to the microcomputer 40. 7 solenoid valve drive circuit 37 operates the original solenoid valve 21.7 in response to a control signal from the microcomputer 40. The proportional valve drive circuit 50, which is a relay circuit that opens and closes the 1 electric 1 common valve 22, energizes the proportional valve 23 in response to the control from the microcomputer 40. The proportional valve drive circuit 50 operates proportionally so that when the opening degree changing circuit 60 described below operates, the opening degree is different from the opening degree determined by the control type 1+ from the microcomputer 40. valve 23
Change the opening degree.

The opening degree changing circuit 60 has an opening degree of 9 of the proportional valve 23 and a microcomputer 4.
l to change the opening degree to a different degree from the opening degree by the control voltage of 0;
= There is a circuit. This opening degree changing circuit 60 is activated only when the flame detection signal from the flame detection circuit 38 is received manually.
, : A certain amount of time later. In addition, this example ゛τ′ is
The opening degree changing circuit 60 sends a signal that decreases the opening degree of the proportional valve 23 to the proportional valve drive circuit 50.

The flame detection circuit 38 is a circuit that generates a flame detection signal using the flame rod 15 installed close to the burner nil, and when a flame is detected, a high level signal is output. In addition to starting combustion and hot water supply in sequence, after a predetermined period of time has elapsed since the B-T group 11 was fired, the controller 31, each Mister 25, 28 and The combustion amount and hot water supply 1 are determined based on the signal from the water flow sensor 27, and the blower 12, proportional valve 23, and water flow control valve 26 are controlled based on the signal. In order to achieve safe and reliable ignition, the blower 12 is controlled to a slow ignition speed, and the proportional valve 23 is controlled to give a slow ignition current.

Next, the proportional valve drive circuit 50 and the opening degree changing circuit 00 are connected to the third
The situation will be explained based on the figure 7. The terminal 51 of the proportional valve drive circuit 50 is connected to the opening determined by the microcomputer 40. , the second sub-control voltage is applied from the microcomputer 40, and the terminal 5] is the positive input terminal of the operational amplifier 52: r
-52a. The output terminal 521) of the operational amplifier 52 is connected to the base of the transistor 54 through a resistor 53, the emitter of the transistor 54 is grounded through a resistor 55, and the proportional valve 23 is connected to the collector of the transistor 54. The proportional valve 23 is powered by the power supply ■
It is connected to Do.

The negative input terminal 52c of the operational amplifier 52 is connected to the capacitor 56.
It is connected to the output terminal 52b of the operational amplifier 52 through the resistor 57, and is connected to the transistor 54 and the resistor 5 through the resistor 57.
It is connected to a connection point 58 with 5.

The operational amplifier 52 has a positive input terminal 52a and a negative input terminal 52.
In order to carry out differential amplification according to the voltage difference with c, the proportional valve drive circuit 50 energizes the proportional valve 23 with a current value according to the voltage applied to the terminal 51.

The opening degree changing circuit 60 includes a timer circuit using a comparator 61,
It consists of a switching circuit using a transistor 76,
With the following configuration, the comparator y161 outputs a high-level signal for a certain period of time (for example, 1.5 seconds) after the signal input to the terminal 62 changes from low level to high level, and at this time, the 76 lowers the control voltage to the proportional valve drive circuit 50 to reduce the current flowing to the proportional valve 23 and change its opening degree.

The positive input terminal 61a of the comparator 361 receives the divided voltage of the power supply VCC divided by the resistors 63 and 64. A resistor 65 that determines a time constant and a capacitor 66 are connected to the negative input terminal 61b of the comparator 61, and the resistor 65 is connected to the power supply v.
Cc, and the capacitor 66 is grounded.

The anode of a diode 68 is connected to the negative input terminal 61b of the comparator 61 through a resistor 67. moreover,
The anode of a diode 69 is connected to the cathode of the diode 68, and the cathode of the diode 69 is connected to the terminal 62.

At the connection point 70 between the diode 68 and the diode 69,
A resistor 71 connected to a power supply vcC is connected. Further, the base of a PNP type transistor 72 is connected to the connection point 70. The emitter of the transistor 72 is connected to the power supply VCC, and the phase of the input signal is inverted and outputted from the collector.

The collector of the transistor 72 is connected to the base of an NPN type transistor 73, and the collector of the transistor 73 is connected to the output terminal 61c of the comparator 61.

The output terminal 61c of the comparator 61 is connected to the anode of a diode 74, and the cathode of the diode 74 is connected to the base of a transistor 76 through a resistor 75. The emitter of the transistor 76 is grounded, and the collector is connected to the °C terminal 'f-51 through a resistor 77.

In the opening degree changing circuit 60, a signal from the flame detection circuit 38 is input to a terminal 62, and when this signal is at a low level, the electric charge in the capacitor 66 is transferred to a resistor 67 and a diode 68.
, the potential of the positive input terminal 61a is the same as that of the negative input terminal ? because it is discharged by the diode 69. The potential is higher than that of 6 l b. Therefore, comparator 61 outputs a high level.

However, at this time, the potential at the connection point 70 is set to a low level by the diode 69, so the transistor 72 outputs a high level, and this signal causes the transistor 73 to output a low level, so the comparator 361 outputs a high level. However, the potential of the output terminal 61c of the comparator 61 is set to low level. Therefore, no current flows into the base of the transistor 76, and the potential of the terminal 51 maintains the control voltage from the microcomputer 40.

When the signal to the terminal 62 changes from low level to high level, the potential at the connection point 70 becomes high level, so the outputs of transistors 72 and 73 are inverted, and the output of transistor 73 becomes high level. Therefore, comparator 6
The output terminal 61c of 1 becomes high level, and the diode 7
4 and resistor 75 into transistor 76, transistor 76 is turned on, thereby lowering the potential at terminal 51. Here, microcontroller 4
By lowering the zero control voltage, the current value to the proportional valve 23 is reduced.

On the other hand, the capacitor 66 stops discharging, current flows into the capacitor 66 from the resistor 65, and the capacitor 66
6 is charged, its potential gradually rises, and after a certain period of time, the output of the comparator 61 is inverted and becomes a low level.

As a result, current no longer flows into the 1-Rangistaff 6, and the proportional valve drive circuit 50 is connected to the terminal 51 from the microcomputer 40.
A current value of -1 is applied to the proportional valve 23 in accordance with the control voltage applied to the proportional valve 23.

Next, the operation of the gas combustion type water heater 1 of this embodiment having the above configuration will be explained based on the solid line A in FIG. 4.

When the user operates the power switch 31 and opens the hot water tap (not shown), water passes through the water supply pipe 17 and flows into the heat exchanger 13. .

At this time, the water flow sensor 27 generates a pulse corresponding to the inflow of water 17, and the incoming water temperature is detected by the incoming water temperature thermistor 25.The water flow detection circuit 32 detects a pulse when the input pulse reaches a predetermined number of 1. Generates a water signal and sends it to the microcomputer/10.

When the water flow signal is input to the microcomputer 40, the air blower 8!11
．． 2 is driven to a predetermined rotation speed for slow ignition, time t1
When the operation of the blower 12 is detected based on its rotation speed, the microcomputer 40 activates the ignition! In ~, the sparker 14 is activated to control the original solenoid valve 211 and the main solenoid valve 22 to open states, and to control the proportional valve 23 to a gentle ignition opening degree.

With this wide open point, burner group 1] is ignited safely and reliably.

This is a predetermined opening degree, and is obtained by the proportional valve drive circuit 50 energizing the proportional valve 23 with the slow ignition current value 1a in accordance with the control voltage from the microcomputer 40.

Then, the fuel gas in the fuel pipe 20 passes through the main solenoid valve 21 and the main solenoid valve 22, is adjusted to the supply amount for slow ignition by the proportional valve 23, and is ejected from the nozzle 16a of the nozzle tK16 to the burner group 11. Ru. The ejected fuel gas is mixed with combustion air supplied by the feeder 12, and ignited safely and reliably by the sparker 4.

At time opening t2, when ignition in burner group 1 is detected by the flame detection circuit 15, the output of the flame detection circuit 38 changes from low level to high level, changing the opening degree. The signal input to terminal 62 of circuit 60 also changes accordingly.

Then, the output of the comparator 61 becomes high level for a certain period of time, and the transistor 76 is turned on for a certain period of time in accordance with the fidgeting. Therefore, the control voltage from the microcomputer 40 applied to the terminal 51 of the proportional valve drive circuit 50 decreases, and the proportional valve 2
The current value to 3 is shown by the solid line A in Figure 4.
The opening degree of the proportional valve 23 decreases by I;=me, the opening degree of the proportional valve 23 is 7. The opening degree becomes smaller than the slow ignition opening degree for a certain period of time Δt during which the opening degree changing circuit 60 operates.As a result, after ignition is detected, the amount of fuel supplied to the burner group 11 decreases and the air-fuel ratio changes.

When the ignition operation ends at time ml t 3, the blower 1.2 and the proportional valve 23 are controlled so that the temperature set by the user in the controller 31 is reached, and the controller 3], each 25.28 and water flow sensor 27
The rotational speed and the t-flow are changed according to the signals from the microcomputer 40. At this time, the output of the opening degree 9: further circuit 60 is fixed at low 17 bells, so the proportional valve drive circuit 50 changes the output from the microcomputer 40. The proportional valve 23 outputs a current value corresponding to the control voltage.
Therefore, what relationship does the size, shape, exhaust i, etc. of the combustion amount case 10 have with the combustion plate of burner group 1, and does it resonate during steady combustion? In a gas combustion type water heater 1 that is configured so that 1 does not occur, the 4th
As indicated by the broken line B in the figure, even if a resonance sound is generated when a slow ignition current is applied to the proportional valve 23, according to the present invention, the fuel supply amount is changed at the same time as ignition is detected.
4. Since the air-fuel ratio of the resonance sound generation condition can be changed every time, a common sound will not be generated after ignition is detected.4
As described in -1- above, according to the present invention, the burner can be ignited accurately and reliably, and resonance noise is not generated at the initial stage of ignition.

In the above embodiments, the opening degree of the proportional valve is reduced, but depending on the combustion equipment, the opening degree may be increased.

Furthermore, the combustion appliance is not limited to a water heater, but may be a heater, a bathtub, or a cooking appliance.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a control device for a gas combustion water heater showing an embodiment of the present invention, FIG. 2 is a schematic diagram showing the configuration of a gas combustion water heater showing an embodiment of the invention, and FIG. FIG. 4 is a circuit diagram showing a proportional valve drive circuit and an opening degree changing circuit in the control device of this embodiment, and a time chart for explaining the operation of this embodiment. In the figure, 15...flame rod (ignition detection means), 2
1... Original solenoid valve (solenoid valve), 22... Main solenoid valve (solenoid valve), 23... Proportional valve, 60... Opening degree changing circuit (
means for changing the opening degree).

Claims (1)

[Claims] 1) A solenoid valve and a proportional valve are provided in a fuel supply path that supplies fuel to a burner, and when the burner is ignited, the solenoid valve is opened and the proportional valve is slowly ignited. The combustion control device controls the opening degree of the proportional valve according to a set combustion amount after the ignition operation, the combustion control device comprising: an ignition detection means for detecting ignition of the burner; an opening degree changing means for changing the opening degree, and at the same time when the ignition detection means detects ignition of the burner, changes the opening degree of the proportional valve to an opening degree different from the slow ignition opening degree,
A combustion control device characterized by maintaining a changed opening degree for a predetermined period of time.