JP3274626B2 - Combustion equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a combustion apparatus for performing stable combustion while maintaining a constant air ratio.

[0002]

2. Description of the Related Art Conventionally, in a gas water heater or a gas fan heater as a combustion device, a proportional control valve for adjusting a supply amount of fuel gas to a burner and a blower for adjusting a supply amount of combustion air to the burner are provided. For example, even if the supply amount of combustion air fluctuates due to disturbance such as blockage of an intake pipe or an exhaust pipe, the burner is controlled so that the ratio of the supply amount of fuel gas and combustion air to the burner is kept constant. The so-called air-fuel ratio control, which controls the supply amount of fuel gas or the supply amount of combustion air to the engine, prevents misfire or incomplete combustion from occurring, and performs stable combustion. .

As the air-fuel ratio control, for example, the ratio of the amount of air actually supplied to a burner by a blower to the amount of air required for combustion determined according to the amount of fuel gas supplied to the burner is determined. Is the air ratio λ (actual supply air amount /
Air ratio detection means for detecting the required air amount), and the opening of the proportional control valve is adjusted so that the air ratio λ detected by the air ratio detection means is maintained at one or more predetermined reference air ratio λB. Is known.

As an air ratio detecting means, there is a means for providing a thermocouple near a burner and detecting an air ratio λ from a correlation between a thermoelectromotive force V of the thermocouple and an air ratio λ. As shown in FIG. 1, the correlation between the thermoelectromotive force V and the air ratio λ is as follows.
It becomes a quadratic curve convex upward.

When the thermoelectromotive force V of the thermocouple exceeds the reference voltage VB corresponding to the reference air ratio λB, the amount of fuel supplied to the burner is reduced by the proportional control valve to increase the air ratio λ. When the voltage is lower than the reference voltage VB, by increasing the amount of fuel supplied to the burner by the proportional control valve to decrease the air ratio λ, stable combustion can be performed while maintaining the air ratio λ at λ = λB.

However, the present inventors have found that the thermoelectromotive force V of the thermocouple with respect to the air ratio decreases due to deformation and aging of the thermocouple. When the thermoelectromotive force V of the thermocouple with respect to the air ratio λ is reduced, even if the air ratio λ is reduced by increasing the fuel supply amount to the burner by the proportional control valve, the thermoelectromotive force of the thermocouple is reduced. V is the reference air ratio λB
It has been found that the state does not increase to the reference voltage VB corresponding to.

In this case, the proportion of fuel supplied to the burner is increased by the proportional control valve so that the thermoelectromotive force V of the thermocouple approaches the reference voltage VB corresponding to the reference air ratio λB. Is reduced, the burner continues to burn with an extremely small air ratio λ because the thermoelectromotive force V of the thermocouple does not reach the reference voltage VB. CO) and nitrogen oxides (NO
x) is disadvantageously generated in a large amount.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned problems, and when the electromotive force of a thermocouple decreases due to deformation or aging of the thermocouple, a large amount of carbon monoxide or nitrogen oxide is generated. It is an object of the present invention to provide a combustion device that does not perform any combustion.

[0009]

According to a first embodiment of the present invention, there is provided a burner, a proportional control valve for adjusting a fuel supply amount to the burner, and a burner when the burner is burning. A blower that supplies combustion air to the burner, and an air ratio that is installed facing the burner and is an air ratio that is a ratio between an actual amount of air supplied to the burner by the blower and an amount of air necessary for combustion of the burner. A thermocouple that generates a corresponding thermoelectromotive force, and a thermocouple of the thermocouple so that the thermoelectromotive force of the thermocouple matches a reference voltage corresponding to a reference air ratio set to one or more predetermined values. When the electric power exceeds the reference voltage, the proportional control valve performs first control for reducing the fuel supply amount to the burner. When the thermoelectromotive force of the thermocouple is less than the reference voltage, the proportional control valve To increase the amount of fuel supplied to the burner A proportional valve control means for performing control, the proportional valve control means, when performing the second control, a state in which the proportional control valve is opened to a predetermined limit opening degree, a predetermined state If you continue for more than an hour,
It is characterized by having stop control means for stopping combustion of the burner.

[0010] The proportional valve control means increases the opening of the proportional control valve when the thermoelectromotive force of the thermocouple is less than the reference voltage during combustion of the burner, thereby increasing the heat of the thermocouple. Until the electromotive force matches the reference voltage, control is performed to increase the amount of fuel supplied to the burner. However, when the thermoelectromotive force of the thermocouple with respect to the air ratio decreases due to the aging of the thermocouple or the like, the proportional control valve is opened to a predetermined limit opening to increase the fuel supply amount to the burner. Even when the air ratio is reduced, there may be a case where the thermoelectromotive force of the thermocouple does not increase to the reference voltage.

In this case, according to the present invention, when the second control is being performed, the stop control means of the proportional valve control means sets the opening of the proportional control valve to the limited opening. When a certain state continues for the predetermined time or more,
The thermoelectric power of the thermocouple with respect to the air ratio decreases, and it is determined that the thermoelectric power of the thermocouple does not reach the reference voltage, and the combustion of the burner is stopped. Therefore, combustion of the burner is not continued in a state where the air ratio is small, and it is possible to prevent a large amount of carbon monoxide and nitrogen oxide from being generated.

According to a second embodiment of the present invention, there is provided a burner, a proportional control valve for adjusting a fuel supply amount to the burner,
A blower for supplying air for combustion to the burner; and a blower installed facing the burner, the amount of air supplied to the burner by the blower when the burner burns and the amount of air required for combustion of the burner. A thermocouple that generates a thermoelectromotive force according to an air ratio that is a ratio, so that the thermoelectromotive force of the thermocouple matches a reference voltage corresponding to a reference air ratio set to a predetermined value of 1 or more. When the thermoelectromotive force of the thermocouple exceeds the reference voltage, the proportional control valve performs first control for reducing the fuel supply amount to the burner, and the thermoelectromotive force of the thermocouple is less than the reference voltage. And a proportional valve control unit that performs a second control for increasing a fuel supply amount to the burner by the proportional control valve, wherein the proportional valve control unit performs the second control. In addition, the thermoelectromotive force of the thermocouple increases When detecting that the decrease later is characterized in that it has a stop control means for stopping the combustion of the burner.

The correlation graph between the air ratio and the thermoelectromotive force of the thermocouple is an upwardly convex quadratic curve in which the thermoelectromotive force of the thermocouple becomes maximum when the air ratio is 1. Therefore, when the proportional valve control means increases the fuel supply amount to the burner by the proportional control valve to reduce the air ratio, the thermoelectromotive force of the thermocouple increases without reaching the reference voltage. The fact that it is detected that the thermocouple has decreased after that can be determined that the thermoelectric force of the thermocouple with respect to the air ratio has decreased due to deformation or aging of the thermocouple, and has not increased to the reference voltage.

According to the present invention, the stop control means of the proportional valve control means detects that the thermoelectromotive force of the thermocouple decreases after the increase while the second control is being performed. Then, it is determined that the thermoelectromotive force of the thermocouple with respect to the air ratio has decreased, and the combustion of the burner is stopped. Therefore, as before, the burner does not continue burning even after the thermoelectromotive force of the thermocouple increases and then decreases, that is, even after the air ratio becomes less than 1, and the carbon monoxide and nitrogen oxides do not continue. Can be prevented from occurring in large quantities.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention is shown in FIGS.
This will be described with reference to FIG. FIG. 1 is a correlation graph between the thermoelectromotive force of a thermocouple provided in the combustion device of the first embodiment and the air ratio, FIG. 2 is a system configuration diagram of a water heater that is the combustion device of the first embodiment, FIG. 3 is a control block diagram of the air ratio of the water heater shown in FIG. 2, and FIG. 4 is a flowchart showing an operation of controlling the air ratio of the water heater shown in FIG.

Referring to FIG. 2, a water heater according to the first embodiment is for discharging hot water at a target temperature set by a user, wherein 1 is a water heater main body, and 2 is a water heater main body 1. Burner accommodated in the combustion chamber 3 formed in the above, 4 is a heat exchanger provided in the water heater body 1 above the combustion chamber 3, 5 is a gas supply pipe for supplying fuel gas to the burner 2, and 6 is A hot water supply pipe piped through the heat exchanger 4, a blower 7 for supplying combustion air to the burner 2 in the combustion chamber 3, a controller 8 for controlling the operation of the hot water supply, a setting operation 9 for setting the tap water temperature, etc. This is an operating device for performing. In the combustion chamber 3, an ignition electrode 10 for generating a spark discharge for igniting the burner 2 and a thermocouple 11 for detecting a combustion state of the burner 2 (presence or absence of misfire or ignition) are arranged.

The blower 7 faces a suction port 13 of a combustion air introduction passage 12, and a fan 1 provided in the introduction passage 12.
4 and a fan motor 15 that rotationally drives the fan 14. By the rotation of the fan 14, combustion air required for combustion of the burner 2 is sucked from the intake port 13 of the introduction path 12, and the combustion air is The fuel is supplied to the combustion chamber 3 through the introduction path 12.

The fan motor 15 is provided with a rotation speed sensor 16 for detecting the rotation speed of the fan motor 15.

The gas supply pipe 5 is provided in order from the upstream side.
A main solenoid valve 17 for opening and closing the gas supply pipe 5;
And a proportional control valve 18 for adjusting the amount of fuel gas supplied to the burner 2.

The hot water supply pipe 6 has a flow rate sensor 19 for detecting the amount of water passing through the hot water supply pipe 6 upstream of the heat exchanger 4 and an incoming water temperature sensor 20 for detecting the temperature of water supplied to the heat exchanger 4. Is provided downstream of the heat exchanger 4, and a tapping temperature sensor 21 for detecting the temperature of water heated by the heat exchanger 4 is provided. In this case, the incoming water temperature sensor 20 and the outgoing water temperature sensor 21 are constituted by, for example, thermistors that are heat-sensitive resistance elements.

The downstream end of the hot water supply pipe 6 is connected to a hot water tap (not shown) in, for example, a kitchen.

The operating device 9 is provided with a temperature setting switch 22 for setting a hot water supply target temperature, and a display 23 for notifying the hot water supply target temperature and abnormality of the water heater.

The controller 8 is constituted by an electronic circuit such as a microcomputer, a memory, an I / O unit, etc., and is a fan motor which is detected via the sensors 16, 19, 20, 21 and the thermocouple 11, respectively. Fifteen
The ignition electrode 10, the fan motor 15, the main solenoid valve 17, the proportional control valve 18, the display The operation of the vessel 23 is controlled.

Here, referring to FIG.
An outline of the basic operation control of the water heater according to the present invention will be described.

A user operates a hot water tap (not shown) attached to a downstream end of the hot water supply pipe 6 shown in FIG.
When water flow to the hot water supply pipe is detected by the flow rate sensor 19,
The controller 8 drives the fan motor 15 to start supplying the combustion air to the burner 2. Further, the controller 8 opens the main solenoid valve 17 to start supplying fuel gas to the burner 2. Then, in this state, the controller 8
Causes a spark discharge at the ignition electrode 10 via a sparker (not shown) (high voltage generating circuit) to ignite the burner 2 and start burning the burner 2.

As shown in FIG. 3, the controller 8 includes a proportional valve control means 30, a target combustion amount calculating section 31, a motor drive circuit 32, and an electromagnetic valve drive circuit 41, and the burner 2 starts combustion. When this is done, the target combustion amount calculation unit 31 outputs the flow rate sensor 19, the incoming water temperature sensor 20, and the outgoing water temperature sensor 21.
Based on the detection data of the amount of water flowing through the hot water supply pipe 6, the incoming water temperature and the outgoing water temperature, respectively, and the target temperature of the outgoing water temperature set by the hot water temperature setting switch 22, the outgoing water temperature matches the target temperature. The target combustion amount of the burner 2 is obtained every moment.

Then, the target combustion amount calculation unit 31 instructs the motor drive circuit 32 of a target rotation speed such that combustion air corresponding to the target combustion amount is supplied to the burner 2.
The motor drive circuit 32 adjusts the power supplied to the fan motor 15 so that the target rotation speed matches the actual rotation speed of the fan motor 15 detected by the rotation speed sensor 16.

The proportional valve control means 30 uses a basic energization amount calculating section 33 provided therein to control the rotation speed sensor 1.
6 to the burner 2 by calculating the amount of power to the proportional control valve 18 in accordance with the detection value of 6, and supplying power to the proportional control valve 18 via the amount of power determination unit 34 to vary the opening of the proportional control valve 18. Adjust the supply of fuel gas. Thereby, the hot water supply pipe 6
The supply amount of the combustion air to the burner 2 and the supply amount of the fuel gas are adjusted such that the hot water temperature of the burner matches the set temperature.

The proportional valve control means 30 includes the fan 14
Is the ratio of the supply amount of combustion air actually supplied to the burner 2 to the supply amount of air required for combustion at the target combustion amount (the actual supply air amount / necessary air amount). Is maintained at a predetermined reference air ratio λB to perform combustion. A reference voltage calculator 35 provided in the proportional valve controller 30;
The comparing unit 36 and the correction value calculating unit 37 are for controlling such an air ratio.

Hereinafter, control of the air ratio by the proportional valve control means 30 will be described. There is a correlation between the thermoelectromotive force V of the thermocouple 11 and the air ratio λ, and the correlation graph shows an upwardly convex shape in which the thermoelectromotive force V is maximum at the air ratio λ = 1 as shown in FIG. It becomes a quadratic curve. And, as the air ratio λ is larger,
Carbon monoxide (CO) and nitrogen oxides (N
Since the amount of Ox) decreases, in the first embodiment, the reference air ratio λB is set to 1.3, which is larger than 1, and the burner 2 burns with the air ratio λ of 1.3. Control is performed.

Note that the actual control is performed using the thermoelectromotive force V of the thermocouple corresponding to the air ratio λ without directly treating the air ratio λ. That is, in the graph of FIG.
Is controlled such that the burner 2 burns in a state where the thermoelectromotive force V of the thermocouple 11 is the reference voltage VB ± 0.2 mV.

The thermoelectromotive force V of the thermocouple 11 and the air ratio λ
Since the maximum value and the slope of the correlation graph change in accordance with the combustion amount of the burner 2, the reference voltage calculation unit 35 determines the rotation speed of the fan motor 15 (corresponding to the combustion amount of the burner 2).
, The reference voltage VB of the thermocouple corresponding to the reference air ratio λB is determined.

FIG. 4 is a flow chart showing the control operation of the air ratio λ by the proportional valve control means 30, based on the basic energizing amount to the proportional control valve 18 calculated by the basic energizing amount calculating section 33. The proportional control valve 18 is calculated by the following equation.
In this case, the air ratio λ is controlled by adjusting the amount of electricity supplied to the power supply.

Referring to FIG. 4, proportional valve control means 30 substitutes (resets) 0 for flag F in STEP 1 and sets correction value α to 1 (no correction) in STEP 2. ), The comparison unit 36 in STEP3
As a result, the thermoelectromotive force of the thermocouple 11 becomes the reference voltage VB -0.2
It is determined whether it is less than mV. The flag F is for controlling the activation of the 20-second timer in STEP5 as described later.

In step 3, the proportional valve control means 30 determines that the thermoelectromotive force of the thermocouple 11
If it is determined that the value is not less than −0.2 mV,
In STEP 20, 0 is substituted (reset) for the flag F in STEP 20, and in STEP 21, the thermocouple 1 is set by the comparing unit 36.
Then, it is determined whether or not the thermal electromotive force exceeds the reference voltage VB + 0.2 mV.

If the comparing section 36 determines in step 21 that the thermoelectromotive force of the thermocouple 11 does not exceed the reference voltage VB + 0.2 mV, the flow branches to step 3. That is, when the thermoelectromotive force of the thermocouple 11 is within the range of the reference voltage VB ± 0.2 mV, STEP3, STEP20, STE
P21 is repeatedly executed to increase or decrease the correction value α, that is, to increase or decrease the amount of electricity supplied to the proportional control valve 30,
Is not adjusted.

On the other hand, in STEP 21, the comparison unit 3
6, the thermoelectromotive force of the thermocouple 11 becomes equal to the reference voltage VB + 0.2.
If it is determined that the voltage exceeds mV, STEP 22
Proceed to. In STEP 22, the correction value calculation unit 37
0.1 is subtracted from the correction value α. As a result, the amount of power to the proportional solenoid valve 18 calculated by the amount-of-current determining unit 34 is reduced.

Then, the flow returns to STEP 3 after waiting for 3 seconds to elapse in STEP 23. In step 3, it is determined that the thermoelectromotive force of the thermocouple 11 is not less than the reference voltage VB -0.2 mV, and in step 21, the thermoelectromotive force of the thermocouple 11 is
When it is determined that B + 0.2 mV is exceeded, 0.1 is subtracted again from the correction value α by the correction value calculation unit 37 in STEP 22, and the subtraction is supplied to the proportional control valve 18 via the energization amount determination unit 34. The amount of supplied electricity is reduced. That is, STE
At P21, the thermoelectromotive force of the thermocouple 11 becomes equal to the reference voltage VB + 0.2.
Until the voltage becomes equal to or less than mV, the first control is executed in STEP 22 in which the amount of electricity supplied to the proportional control valve 18 is reduced to reduce the opening of the proportional control valve 18 and the amount of fuel gas supplied to the burner 2. .

On the other hand, in STEP 3, the comparing unit 36
When it is determined that the thermoelectromotive force of the thermocouple 11 is less than the reference voltage VB -0.2 mV, the process proceeds to STEP 4 and proceeds to ST4.
If the correction value α is less than 1.5 which is the upper limit value of the correction value α in EP4, the flow branches to STEP30. And STE
In P30, the correction value calculation unit 37 adds 0.1 to the correction value α to increase the amount of current supplied to the proportional control valve 18 via the amount of current determination unit 34, and waits for 3 seconds in STEP31. Wait and return to STEP3. That is, until the thermoelectromotive force of the thermocouple 11 becomes equal to or higher than the reference voltage VB-0.2 mV in STEP 3, the amount of electricity supplied to the proportional control valve 18 is increased in STEP 30 to increase the opening of the proportional control valve 18, The second control for increasing the supply amount of the fuel gas to the fuel cell 2 is executed.

When the proportional control means 30 performs the second control, the correction value α is changed to the correction value α in STEP4.
When the upper limit of 1.5 is reached, the process proceeds to STEP5. STEP5 to STEP9 are operation flows of the stop control means 40 provided in the proportional valve control means 30.

While the proportional valve control means 30 is executing the second control, if the correction value α reaches the upper limit value of 1.5 in STEP 4, the flag F is set to 0 (reset state). Since there is, the process proceeds from STEP5 to STEP6. Then, the stop control means 40 sets the flag F to 1 in STEP6.
Is substituted (set), and a 20-second timer is started in STEP7.

Until the 20-second timer expires in STEP 8, the process branches from STEP 8 to STEP 3. At this time, since the flag F is 1 (set), STEP
The YES branch of 5 advances to STEP 8, and the 20-second timer is not restarted. Therefore, as long as the thermoelectromotive force of the thermocouple 11 is less than the reference voltage VB-0.2 mV in STEP 3, S
The loop of STEP3, STEP4, STEP5, STEP8 is repeatedly executed.

When the thermoelectromotive force of the thermocouple 11 becomes equal to or higher than the reference voltage VB-0.2 mV in STEP 3, the stop control means 40 stops its operation and proceeds from STEP 3 to STEP 3.
The process branches to 20 to substitute (reset) 0 for the flag F.
Further, when the 20-second timer expires in STEP 8, the thermoelectromotive force of the thermocouple 11 does not increase to the reference voltage VB even if it waits longer, as shown in FIG. Can be determined to be in a state where the thermoelectromotive force V has decreased. Therefore, the stop control means 40 proceeds to STEP 9 and cuts off the power supply to the main electromagnetic valve 17 via the electromagnetic valve drive circuit 41, closes the main electromagnetic valve 17, and stops the combustion of the burner 2.

By the operation of the stop control means 40, FIG.
As shown in B, when the thermoelectromotive force of the thermocouple 11 with respect to the air ratio decreases, the correction value α becomes the upper limit of 1.5.
After 20 seconds have elapsed, the combustion of the burner 2 is stopped. Therefore, combustion of the burner 2 is continued in a state where the air ratio is small, and it is possible to prevent a large amount of carbon monoxide (CO) and nitrogen oxide (NOx) from being generated.

Next, a second embodiment of the present invention will be described. The device configuration of the second embodiment is the same as that of the first embodiment shown in FIGS. 2 and 3, except that the conditions for determining that the thermoelectromotive force of the thermocouple 11 has decreased with respect to the air ratio are different. Hereinafter, the control method of the air ratio according to the second embodiment will be described with reference to the flowchart shown in FIG.

Referring to FIG. 5, STEP 1 to STEP 1
3 and the first control processing in STEP20 to STEP23 are the same as those in the first embodiment.
The processing after STEP 51 when it is determined that the electromotive force of the thermocouple 11 is less than the reference voltage VB-0.2 mV,
That is, the processing method of the second control is different.

In step 51, the stop control means 40 provided in the proportional valve control means 30 holds the thermoelectromotive force of the thermocouple 11 at that time in a variable VR. Then, in STEP 52, 0.1 is added to the correction value α by the correction value calculation unit 37, the supply current to the proportional control valve 18 is increased via the energization amount determination unit 34, and the opening of the proportional control valve 18 is reduced. It is increased to increase the supply amount of the fuel gas to the burner 2.

Then, after waiting for three seconds to elapse in STEP 53, the flow goes through STEP 54 (at this time, F =
0) Proceed to STEP 55, and in STEP 55, the stop control means 40 determines that the thermoelectromotive force of the thermocouple 11 at that time is larger than the thermoelectromotive force of the thermocouple 11 at 3 seconds before held at VR, that is, , One thermocouple for decreasing air ratio λ
When the air ratio λ in the graph of FIG. 1 is in a range exceeding 1, the thermoelectromotive force V of 1 is increased, and the process branches to STEP3.
That is, in Step 3, the thermoelectromotive force of the thermocouple 11 becomes equal to the reference voltage V.
B-As long as it is less than 0.2 mV, STEP3 to STEP
55 is repeatedly executed.

Then, in STEP 55, when the thermoelectromotive force of the thermocouple 11 at that point in time becomes equal to or less than the thermoelectromotive force of the thermocouple 11 held 3 seconds before the VR, that is, in the graph of FIG. The thermoelectromotive force V of the thermocouple 11 with respect to the decrease of the air ratio λ
Does not increase, and the state is in a region where the air ratio λ is 1 or less, the flag F is set in STEP56. As a result, as long as the thermoelectromotive force of the thermocouple 11 is less than the reference voltage VB-0.2 mV in STEP 3,
EP3 to STEP54 and STEP57 are repeatedly executed.

In STEP 57, the thermoelectromotive force of the thermocouple 11 at that time is set to 3 seconds before the thermocouple 11 held at VR.
, Ie, in the graph of FIG. 1,
When the electromotive force of the thermocouple 11 decreases in response to the decrease in the air ratio λ, and the state is in a region where the air ratio λ is less than 1, the process proceeds to STEP 58.

As described above, when it is detected in STEPs 55 and 56 that the thermoelectromotive force of the thermocouple 11 changes from an increase to a decrease when the air ratio λ is decreased, a graph B shown in FIG. Thus, it can be determined that the thermoelectromotive force of the thermocouple 11 has exceeded the maximum value (thermoelectromotive force when λ = 1). In this case, even if the air ratio is decreased by further increasing the correction value α, the thermoelectromotive force of the thermocouple 11 does not increase and does not reach the reference voltage VB. Therefore, the stop control means 40 cuts off the power supply to the main solenoid valve 17 via the solenoid valve drive circuit 41 in STEP 58, closes the main solenoid valve 17, and stops the combustion of the burner 2.

By the operation of the stop control means 40, the combustion of the burner 2 is continued even after the air ratio becomes less than 1, and
A large amount of carbon monoxide (CO) and nitrogen oxide (NOx) can be prevented from being generated.

In the first and second embodiments, when the stop control means 40 determines that the thermoelectromotive force of the thermocouple 11 with respect to the air ratio has decreased, the display 23 informs of the abnormality. It may be performed.

In the first and second embodiments, a water heater has been described as an example of a combustion device. However, the present invention can be applied to other combustion devices, for example, a gas fan heater.

[Brief description of the drawings]

FIG. 1 is a graph showing the correlation between the air ratio and the thermoelectromotive force of a thermocouple.

FIG. 2 is a system configuration diagram of a water heater that is a combustion device according to the embodiment of the present invention.

FIG. 3 is a block diagram of a controller provided in the water heater of FIG. 2;

FIG. 4 is an operation flowchart of the controller of FIG. 3;

FIG. 5 is an operation flowchart of the controller of FIG. 3;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Water heater main body, 2 ... Burner, 3 ... Combustion chamber, 4 ... Heat exchanger, 5 ... Gas supply pipe, 6 ... Hot water supply pipe, 7 ... Blower, 8 ... Controller, 9 ... Operating device, 10 ... Ignition electrode, 11 thermocouple, 12 introduction path, 13 intake port, 14 fan, 15
... Fan motor, 16 ... Rotation speed sensor, 17 ... Main solenoid valve, 18 ... Proportional control valve, 19 ... Flow rate sensor, 20 ... Inlet water temperature sensor, 21 ... Outlet water temperature sensor, 22 ... Temperature setting switch, 23 ... Display Reference numeral 30: proportional valve control means, 31: target combustion amount calculation unit, 32: motor drive circuit, 33: basic energization amount calculation unit, 34: energization amount determination unit, 35: reference voltage calculation unit, 36: comparison unit, 37 ... Correction value calculation unit, 40: stop control means, 41: solenoid valve drive circuit

Claims (2)

(57) [Claims] 1. A burner, a proportional control valve for adjusting a fuel supply amount to the burner, a blower for supplying combustion air to the burner, and a blower installed facing the burner, the blower being used for burning the burner. A thermocouple that generates a thermoelectromotive force according to an air ratio that is a ratio of an actual air amount supplied to the burner to an air amount required for combustion of the burner, and a thermoelectromotive force of the thermocouple is: When the thermoelectromotive force of the thermocouple exceeds the reference voltage so as to match a reference voltage corresponding to a reference air ratio set to one or more predetermined values, a fuel supply amount to the burner by the proportional control valve. Proportional control means for performing a second control for increasing the fuel supply amount to the burner by the proportional control valve when the thermoelectromotive force of the thermocouple is less than the reference voltage. The proportional valve control The means includes stop control means for stopping combustion of the burner when the state in which the proportional control valve is opened to a predetermined limit opening degree continues for a predetermined time or more when performing the second control. A combustion device characterized by the following. 2. A burner, a proportional control valve for adjusting an amount of fuel supplied to the burner, a blower for supplying combustion air to the burner, and a blower installed facing the burner, the blower being used for burning the burner. A thermocouple that generates a thermoelectromotive force according to an air ratio that is a ratio of an actual air amount supplied to the burner to an air amount required for combustion of the burner, and a thermoelectromotive force of the thermocouple is: When the thermoelectromotive force of the thermocouple exceeds the reference voltage so as to match a reference voltage corresponding to a reference air ratio set to one or more predetermined values, a fuel supply amount to the burner by the proportional control valve. A proportional valve control means for performing a second control for increasing a fuel supply amount to the burner by the proportional control valve when the thermoelectromotive force of the thermocouple is less than the reference voltage. The proportional valve control The means includes stop control means for stopping the combustion of the burner when detecting that the thermoelectromotive force of the thermocouple increases and then decreases while performing the second control. Combustion equipment.