JP3307561B2 - 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-fuel ratio and 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. There is known an apparatus which performs so-called air-fuel ratio control in which a burner is burned while maintaining a constant ratio between a supply amount of fuel gas to the burner and a supply amount of combustion air.

As such air-fuel ratio control, for example,
An air amount detecting means for detecting a supply flow rate of combustion air to the burner; and when the flow rate detected by the air amount detecting means changes due to disturbance such as blockage of an intake pipe or an exhaust pipe, the rotation speed of the blower is changed. Is adjusted so that the flow rate detected by the air amount detecting means is maintained at a predetermined reference flow rate, so that the supply amount of combustion air to the burner is kept constant.

Normally, since the supply amount of fuel gas does not change due to disturbance, the supply amount of combustion gas is kept constant even when disturbance occurs, so that the supply amount of fuel gas is maintained. The ratio between the amount and the supply amount of combustion air is kept constant, and stable combustion can be performed.

[0005] Further, an air ratio λ (actually, which is a ratio of the amount of air actually supplied to the burner by the blower and the amount of air required for combustion determined according to the amount of fuel gas supplied to the burner). Air ratio detection means for detecting the supplied air amount / required air amount), and opening the proportional control valve so that the air ratio λ detected by the air ratio detection means is maintained at a predetermined reference air ratio λB. Air ratio control to adjust the degree of carbon monoxide (CO) and nitrogen oxides (N
There has been known one in which the amount of Ox) is suppressed.

As an air ratio detecting means, there is a method in which a thermocouple is provided near a burner and an air ratio λ is detected from a correlation between an electromotive force of the thermocouple and an air ratio λ. As shown in FIG. 1, the correlation between the electromotive force of the thermocouple and the air ratio λ is as shown in FIG.
It becomes the following curve.

Therefore, when the reference air ratio λB is set to a value of 1 or more, when the thermoelectromotive force V of the thermocouple exceeds the reference voltage VB corresponding to the reference air ratio λB, the proportional control valve is used. By reducing the amount of fuel gas supplied to the burner to increase the air ratio λ, and when it is lower than the reference voltage VB, the proportional control valve increases the amount of fuel gas supplied to the burner to reduce the air ratio λ. , The air ratio λ to λ
= ΛB.

[0008] By performing the air-fuel ratio control and the air ratio control in parallel, stable burner combustion is performed while suppressing generation of carbon monoxide (CO) and nitrogen oxide (NOx). be able to.

However, when the air-fuel ratio control and the air ratio control are performed in parallel, disturbance such as blockage of the intake port occurs, and the amount of combustion air supplied to the burner decreases sharply and drastically. Sometimes, the process of increasing the rotation speed of the blower by the air-fuel ratio control and the process of increasing the air ratio by reducing the opening of the proportional control valve by the air ratio control are performed simultaneously.

[0010] Generally, the rate of change of the rotation speed with respect to the change in the amount of energization of the fan motor provided in the blower is smaller than the rate of change of the opening degree with respect to the change in the amount of energization of the proportional control valve. Therefore, in this case, the decrease in the opening of the proportional control valve is performed earlier than the increase in the rotation speed of the blower, and the supply amount of the fuel gas to the burner is greatly reduced.

As a result, the amount of combustion (heating) of the burner is greatly reduced. For example, in the case of a water heater, there is an inconvenience that the temperature of the hot water drops suddenly, giving the user discomfort.

[0012]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned disadvantages, and the burner combustion amount does not suddenly decrease even if the supply amount of combustion air to the burner decreases sharply and drastically. It is an object to provide a combustion device.

[0013]

In order to achieve the above object, a first embodiment of the present invention provides a burner, a proportional control valve for adjusting a supply amount of fuel gas to the burner, and a control valve for the burner. A blower for adjusting a supply amount of the combustion air, an air amount detection means for detecting a flow rate of the combustion air supplied to the burner, and a flow rate of the combustion air detected by the air amount detection means being a predetermined value. Blower control means for adjusting the rotation speed of the blower so as to match a reference flow rate, and installed facing the burner, the actual amount of air supplied to the burner by the blower and necessary for combustion of the burner. A thermocouple that generates a thermoelectromotive force according to an air ratio that is a ratio to an air amount; and the proportional control valve so that the thermoelectromotive force of the thermocouple matches a reference voltage corresponding to a predetermined reference air ratio. The opening degree of the The first change rate second is smaller than a change rate of the rotational speed at the time of adjusting the rotation speed of the blower
And proportional valve control means for adjusting at a change rate.

According to the present invention, the second rate of change when the opening degree of the proportional control valve is adjusted by the proportional valve control means is equal to the second change rate when the rotation speed of the blower is adjusted by the blower control means. It is set smaller than the first rate of change. Therefore, when the flow rate of the combustion air to the burner is rapidly reduced due to the disturbance, and the air ratio is also rapidly reduced accordingly, the rotation speed of the blower is increased by the blower control means to keep the air-fuel ratio constant. The maintaining process is performed prior to the process of reducing the opening of the proportional control valve by the proportional valve control means and keeping the air ratio constant.

Therefore, in a state where the supply amount of the combustion air to the burner is rapidly reduced, the opening of the proportional control valve is not immediately reduced by the proportional valve control means. As a result, the process of recovering (increase) the rotation speed of the blower is started, the supply amount of combustion air to the burner increases, and as the air ratio increases, the opening of the proportional control valve decreases. Is done.

Therefore, the amount of decrease in the supply amount of fuel gas to the burner required to make the air ratio detected by the thermocouple equal to the reference air ratio becomes small, and the combustion amount of the burner sharply increases. Can be prevented from decreasing.

A change rate for setting the second change rate to be smaller as the amount of adjustment of the rotation speed of the blower by the blower control means required to make the blower amount of the blower coincide with the reference flow rate is larger. A setting means is provided.

When the supply amount of the combustion air to the burner is greatly reduced, the amount of adjustment of the rotation speed of the blower by the blower control means is increased, and it is necessary to make the blower amount of the blower coincide with the reference flow rate. The time gets longer.
At this time, according to the present invention, the larger the adjustment amount of the rotation speed of the blower is, the smaller the second change rate is set.
Therefore, the speed at which the opening of the proportional valve is reduced by the proportional valve control unit is reduced, and the rotation speed of the blower is adjusted by the blower control unit in advance. Therefore, the amount of decrease in the amount of fuel gas supplied to the burner by the proportional valve control means can be reduced, and a decrease in the burner combustion amount can be prevented.

When the amount of rotation of the blower by the blower control means, which is necessary to make the blower volume of the blower coincide with the reference flow rate, is equal to or greater than a predetermined upper limit, the proportional valve control is performed. An adjustment stopping means for stopping the adjustment of the opening of the proportional control valve by the means is provided.

When the adjustment amount of the rotation speed of the blower by the blower control means exceeds a predetermined upper limit, the supply amount of combustion air to the burner is greatly reduced, and the air ratio is extremely reduced. In state. At this time, when the proportional valve control means reduces the opening of the proportional control valve and tries to make the air ratio match the reference air ratio, the amount of fuel gas supplied to the burner is significantly reduced, Burner combustion is greatly reduced.

In such a case, according to the present invention, the adjustment stop means stops the adjustment of the proportional control valve by the proportional valve control means. Therefore, it is possible to prevent the combustion amount of the burner from being significantly reduced due to the decrease in the supply amount of the fuel gas to the burner.

Further, the air amount detecting means is an air flow sensor.

According to the present invention, by using the air flow sensor, the supply amount of the combustion air to the burner can be easily detected.

Further, the air amount detecting means includes a rotating speed detecting means for detecting a rotating speed of the blower, and a current detecting means for detecting an amount of electricity to the blower. From the amount of electricity to
A flow rate of the combustion air supplied to the burner is detected.

When the supply amount of combustion air to the burner decreases due to a blockage of the intake port or the like, the amount of electricity to the blower required to rotate the blower at a predetermined rotation speed decreases. That is, since the amount of electricity supplied to the blower with respect to the rotation speed of the blower increases and decreases in accordance with the increase and decrease in the amount of combustion air supplied to the burner, the amount of combustion air supplied to the burner is Can be detected.

Therefore, in particular, in a combustion apparatus provided with a rotation speed control means for performing feedback control of the rotation speed of the blower so that the rotation speed of the blower reaches a predetermined target rotation speed, the power supply to the blower is controlled. The air amount detecting means can be configured simply by adding the current detecting means for detecting the amount, and the installation cost of the air amount detecting means can be reduced.

[0027]

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 of the thermoelectromotive force of a thermocouple provided in the combustion device of the first embodiment and the air ratio, and FIG. 2 is a configuration diagram of a water heater as the combustion device of the first embodiment. 3 is a control block diagram of the water heater shown in FIG. 2,
FIG. 4 is a flowchart showing the operation of controlling the air-fuel ratio of the water heater shown in FIG. 2, and FIG. 5 is a flowchart showing the operation of controlling the air ratio of the water heater shown in FIG.

Referring to FIG. 2, the water heater according to the first embodiment taps out hot water at a target temperature set by a user. 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 faces 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 introduction path 12 is provided with an air flow sensor 16 which is an air amount detecting means for detecting a flow rate of the combustion air supplied to the burner 2.

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 flowing 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, for example, a hot water tap (not shown) in a kitchen or the like.

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 burner which is detected via each of the sensors 16, 19, 20, 21 and the thermocouple 11. The ignition electrode 10, the fan motor 15, the main solenoid valve 1
7. Control the operation of the proportional control valve 18 and the display 23.

The control operation of the water heater by the controller 8 will now be described with reference to FIGS.

The user operates a hot water tap (not shown) attached to the downstream end of the hot water supply pipe 6 shown in FIG.
When the flow sensor 19 detects the passage of water through the hot water supply pipe 6, the controller 8 drives the fan motor 15 to start supplying 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 to occur in the ignition electrode 10 via a sparker (high voltage generation circuit) (not shown) to ignite the burner 2 and start burning the burner 2.

As shown in FIG. 3, the controller 8 includes a proportional valve control unit 30, a target combustion amount calculation unit 31, a ventilation control unit 32, a change rate setting unit 33, and an adjustment stop unit 34. When the combustion of the burner 2 is started, the target combustion amount calculating unit 31 detects the flow rate of the hot water supply pipe 6, the incoming water temperature and the outgoing water temperature detected by the flow rate sensor 19, the incoming water temperature sensor 20 and the outgoing water temperature sensor 21, respectively. Based on the data and the target hot water temperature set by the hot water temperature setting switch 22, the target combustion amount of the burner 2 for making the hot water temperature coincide with the target temperature is obtained every moment.

A target air amount calculating section 35 provided in the blower control means 32 calculates a supply amount of combustion air in accordance with the target combustion amount, and uses the supplied amount as a target air amount to calculate an energization amount calculating section. Instruct 36. The energization amount calculation unit 36 determines that the target air amount indicated by the target air amount calculation unit 35 matches the flow rate of the combustion air actually supplied to the burner 2 detected by the air flow sensor 16. The amount of power supply to the fan motor 15 is adjusted.

FIG. 4 is a flow chart showing the operation of controlling the amount of combustion air supplied to the burner 2 by the blower control means 32. Referring to FIG. 4, blower control means 32 substitutes (resets) 0 into flags F1 and F2 in STEP1 and STEP2, respectively. The flags F1 and F2 are
This is for prohibiting the restart of timers T1 and T2 which will be described later.

The ventilation control means 32 substitutes 1 for the correction value β in STEP3. The value of the correction value β is thereafter determined by the energization amount calculation unit 36 and the target air amount indicated by the target air amount calculation unit 35 and the combustion amount actually supplied to the burner 2 detected by the air flow sensor 16. The value is varied according to the difference from the air flow rate, and the amount of power to the fan motor 15 is determined by the following equation.

Power supply amount = reference power supply amount × correction value β The reference power supply amount is determined by the power supply amount calculator 36 in accordance with the target air amount calculated by the target air amount calculator 35.

In STEP 4, the actual air amount detected by the air flow sensor 16 is equal to the target air amount × 9.
If it is 5% or more, the process proceeds to STEP20. And
In STEP 20, the actual air amount is the target air amount × 105%
In the following cases, the process returns to STEP4. That is, when the detected value of the actual air amount by the air flow sensor 16 is within the range of the target air amount ± 5%, STEP4, ST4
EP20 is repeatedly executed, and the correction value β is not changed.

On the other hand, if the detected value of the actual supply amount of combustion air by the air flow sensor 16 is less than the target air amount × 95% in STEP 4, the process proceeds to ST4.
The process proceeds to EP5 (at this time, the flag F1 = 0), and the operation of correcting the amount of energization to the fan motor 15 by the energization amount calculator 36 is started. The energization amount calculation unit 36 substitutes (sets) 1 for F1 in STEP6, substitutes (resets) 0 for F2 in STEP7, and starts the fixed timer T1 in STEP8.

When the fixed timer T1 times out in STEP9, the process proceeds to STEP10, where 0 is substituted (reset) for the flag F1.
6, 0.1 is added to the correction value β. This allows
The fan motor 15 determined by the energization amount calculation unit 36
And the rotation speed of the fan motor 15 increases.

If the fixed timer T1 has not timed out in STEP 9, the process branches to STEP 4. At this time, since the flag F1 is 1 (set state), the STE
In P5, the process branches to STEP9, and the restart of the fixed timer T1 in STEP8 is prohibited.

By the processing in STEP4 to STEP11, the detected value of the actual supply amount of the combustion air by the air flow sensor 16 in STEP4 is calculated by the target air amount × 95.
%, The amount of power to the fan motor 15 is increased each time the fixed timer T1 times out in STEP 9, and the rotation speed of the fan motor 15 is increased.

If the detected value of the actual supply amount of combustion air by the air flow sensor 16 exceeds the target air amount.times.105% in STEP 20, the flow proceeds to STEP 2.
1 (at this time, the flag F2 = 0), and the energization amount calculation unit 3
Step 6 substitutes 1 for the flag F2 in STEP22 (set).
Then, in step 23, 0 is substituted for the flag F1 (reset).
Then, in STEP 24, a fixed timer T2 having a set time of 1 second is started.

When the fixed timer T2 has timed out in STEP25, the process proceeds to STEP26 and the flag F2 is set to 0.
Is substituted (reset), and in STEP 27, 0.1 is subtracted from the correction value β by the energization amount calculation unit 36. As a result, the fan motor 1
5 and the rotation speed of the fan motor 15 decreases.

If the fixed time T2 has not elapsed in STEP25, the flow branches to STEP4. At this time, since the flag F2 is 1 (set state), ST
At EP21, the process branches to STEP25, and the restart of the fixed timer T2 at STEP24 is prohibited.

This STEP 4, STEP 20 to STEP
In the process of step 27, the detected value of the actual air amount by the air flow sensor 16 in STEP20 is calculated by multiplying the target air amount ×
Until it becomes 105% or less, the fixed timer T
Every time 2 times out, the amount of power to the fan motor 15 is reduced, and the rotation speed of the fan motor 15 is reduced.

By the operation of the power supply amount calculating section 36, even if disturbance such as adhesion of dust to the intake port 13 occurs, the supply amount of combustion air to the burner 2 is maintained at the target air amount. Dripping. Since the supply amount of the fuel gas supplied to the burner 2 does not change due to disturbance, the ratio (air-fuel ratio) between the supply amount of the combustion air and the supply amount of the fuel gas can be kept constant. .

As shown in FIG. 3, the proportional valve control means 30 provided in the controller 8
7, a comparing unit 38, a correction value calculating unit 39, a basic energizing amount calculating unit 40, and an energizing amount determining unit 41. The basic energization amount calculation unit 40 determines the supply amount of the fuel gas necessary to obtain the target combustion amount calculated by the target combustion amount calculation unit 31, and sets the opening according to the supply amount of the fuel gas. Then, the basic energization amount to the proportional control valve 18 is calculated.

The reference voltage calculation unit 37, the comparison unit 38, the correction value calculation unit 39, and the energization amount determination unit 41 determine the amount of combustion air actually supplied to the burner 2 and the amount of combustion at the target combustion amount. In order to burn the burner 2, the air ratio λ (actual supply air amount / required air amount), which is a ratio with the supply amount of combustion air necessary for the combustion, is maintained at a predetermined reference air ratio λB.

As shown in the graph of FIG. 1, when the burner 2 is burned, the relationship between the thermoelectromotive force V of the thermocouple 11 and the air ratio λ is λ = 1, and the thermoelectromotive force of the thermocouple 11 is λ = 1. Is the maximum and a quadratic curve convex upward. Therefore, the reference air ratio λ
When B is set to a value of 1 or more, when the thermoelectromotive force V of the thermocouple 11 is lower than the reference voltage VB corresponding to the reference air ratio λB, the opening of the proportional control valve 18 is increased to increase the burner. And supply of fuel gas to the thermocouple 11
When the thermoelectromotive force V exceeds the reference voltage VB, the opening ratio of the proportional control valve 18 is reduced to reduce the amount of fuel gas supplied to the burner 2, thereby reducing the air ratio λ to the reference air ratio λB.
And the burner 2 can be burned.

Incidentally, as the air ratio increases, carbon monoxide (CO) and nitrogen oxide (NOx) generated during combustion of the burner 2 are increased.
Therefore, in the first embodiment, the reference air ratio λB is set to 1.3, which is larger than 1.

Hereinafter, the operation of the air ratio control by the proportional valve control means 30 will be described with reference to the flowchart shown in FIG.

The proportional valve control means 30 comprises the steps 50, 5
At step 1, 0 is assigned to flags F3 and F4 (reset), and ST
In EP52, 1 is substituted for the correction value α. Note that the flags F3,
F4 is for prohibiting the restart of variable timers T3 and T4 to be described later. The value of the correction value α is subsequently determined by the correction value calculation unit 39 in accordance with the difference between the reference voltage VB determined by the reference voltage calculation means 37 according to the target combustion amount and the thermoelectromotive force V of the thermocouple 11. The amount of power supply to the proportional control valve 18 is determined by the following expression using the following formula.

The amount of energization = the basic amount of energization × the correction value α The basic amount of energization is calculated by the basic amount of
At 0, it is calculated according to the target combustion amount determined by the target combustion amount calculation unit 31.

In STEP 53, the comparison unit 38 compares the reference voltage VB with the thermoelectromotive force V of the thermocouple 11, and
The thermoelectromotive force V of the thermocouple 11 is equal to the reference voltage VB -0.2 mV.
If so, the flow branches to STEP 70, and STEP 7
At 0, the thermoelectromotive force V of the thermocouple is equal to the reference voltage VB + 0.2 mV.
If it is below, the flow branches to STEP53. That is,
The thermoelectromotive force V of the thermocouple 11 is equal to the reference voltage VB ± 0.2 mV
Are in the range, STEP53 and STEP70 are repeatedly executed, and the correction value α is not changed.

On the other hand, in STEP 53, the thermocouple 1
When the thermal electromotive force V is less than the reference voltage VB -0.2 mV, the process proceeds to STEP54. STEP 54 is a process performed by the adjustment stopping means 34, and the correction value β of the amount of power to the fan motor 15 calculated by the amount of power calculation unit 36.
(Corresponding to the adjustment amount of the rotation speed of the fan motor 15) exceeds a predetermined upper limit, that is, the flow rate of the combustion air actually supplied to the burner 2 detected by the air flow sensor 16 is: When it is greatly reduced,
The change processing of the correction value α by the proportional valve control means 30 after 55 is prohibited.

When the supply of combustion air to the burner 2 is greatly reduced by the processing of the adjustment stopping means 34 and the air ratio λ is also significantly reduced, the proportional valve control means 30 In order to make the thermoelectromotive force V of the thermocouple 11 corresponding to λ equal to the reference voltage VB corresponding to the reference air ratio λB, the supply amount of the fuel gas to the burner 2 is reduced, and the combustion amount of the burner 2 sharply increases. Can be prevented from decreasing. For this reason, it is possible to prevent the temperature of the hot water discharged from the hot water supply pipe 6 from dropping abruptly, thereby preventing the user from feeling uncomfortable.

Step 55 is a process performed by the change rate setting means 33. The correction value β (the fan motor 15
Variable timer T according to the value of the
3 is longer than 1 second which is the set value of the fixed timer T1 shown in the flowchart of FIG.
Is determined to be longer as the value of is larger.

At this point, since the flag F3 is 0, the process proceeds from STEP 56 to STEP 57, where
In step 57, 1 is substituted (set) in the flag F3,
At step 8, 0 is assigned to flag F4 (reset), and
At 59, the variable timer T3 is started.

When the variable timer T3 has timed out in STEP60, the process proceeds to STEP61 and the flag F3 is set to 0.
Is substituted, and in step 62, the correction value calculation unit 39 adds 0.1 to the correction value α. As a result, the amount of energization to the proportional control valve 18 determined by the energization amount determining unit 41 increases, and the opening of the proportional control valve 18 increases.

If the variable timer T3 has not timed out in STEP60, the flow branches to STEP53. At this time, since the flag F3 is 1 (set state),
At STEP 56, the process branches to STEP 60, and the restart of the timer T3 at STEP 59 is prohibited.

By the processing of STEP53 to STEP62, STEP60 is performed until the thermoelectromotive force V of the thermocouple 11 becomes equal to or higher than the reference voltage VB−0.2 mV in STEP53.
Each time the timer T3 times out, the proportional control valve 18
Is increased, and the opening of the proportional control valve 18 increases.

If the thermoelectromotive force V of the thermocouple 11 exceeds the reference voltage VB + 0.2 mV in STEP 70, the process proceeds to STEP 71. STEP 71 is a process performed by the adjustment stopping means 34. The correction value β (corresponding to the adjustment amount of the rotation speed of the fan motor 15) of the energization amount to the fan motor 15 calculated by the energization amount calculation unit 36 is a predetermined upper limit value. (In this case, the negative side), that is, when the supply amount of the combustion air actually supplied to the burner 2 detected by the air flow sensor 16 is greatly increased, Correction value α by valve control means
Prohibits the change processing of.

When the supply of combustion air to the burner 2 is greatly increased by the processing of the adjustment stopping means 34 and the air ratio λ is also greatly increased, the proportional control means 3
In order to make the air ratio λ equal to the reference air ratio λB, the supply amount of the fuel gas to the burner 2 is increased, so that the combustion amount of the burner 2 can be prevented from increasing rapidly. For this reason, it is possible to prevent the temperature of the hot water discharged from the hot water supply pipe 6 from rapidly rising and giving the user discomfort.

Step 72 is a process performed by the change rate setting means 33. The correction value β (the fan motor 15
The set value of the variable timer T4 is changed to the fixed timer T4 shown in the flowchart of FIG.
2 is set to be longer than 1 second, which is the set value of 2, and to be longer as the value (absolute value) of the correction value β is larger.

Since the flag F4 is 0 at this point, the process proceeds from STEP 73 to STEP 74, and
At 74, 1 is substituted (set) for the flag F4, and STEP7
At step 5, 0 is assigned to flag F3 (reset), and
At 76, the variable timer T4 is started.

If the variable timer T4 has timed out in STEP 77, the flow advances to STEP 78 to set the flag F4 to 0.
Is substituted, and the correction value calculation unit 39 subtracts 0.1 from the correction value α in STEP 79. As a result, the amount of energization to the proportional control valve 18 determined by the energization amount determination unit 41 decreases, and the opening of the proportional control valve 18 decreases.

If the variable timer T4 has not timed out in STEP 77, the flow branches to STEP 53. At this time, since the flag F4 is 1 (set state), S
At STEP 73, the process branches to STEP 77, and the restart of the variable timer T4 at STEP 76 is prohibited.

In steps 53 and 70 to STE
By the process of P79, the amount of power to the proportional control valve 18 decreases every time the variable timer T4 times out in STEP77 until the thermoelectromotive force V of the thermocouple 11 becomes equal to or less than the reference voltage VB + 0.2mV in STEP70. Is done.

By the operation of the proportional valve control means 30 described above, the burner 2 can be burned while maintaining the thermoelectromotive force V of the thermocouple 11 at the reference voltage VB corresponding to the reference air ratio λB.

Here, since the set values of the fixed timers T1 and T2 shown in the flowchart of FIG. 4 are fixed at 1 second, when the correction value β of the energization amount to the fan motor 15 is increased or decreased, The rate of change (first rate of change) of the amount of current (corresponding to the rotation speed of the fan motor 15) is constant.

Therefore, in STEP 55, the change rate setting means 33 sets the set value of the variable timer T3 to a time longer than the set value (1 second) of the fixed timer T1 so that the proportional control means 30 When increasing the correction value α of the amount of power supplied to the control valve 18 (corresponding to the opening of the proportional control valve 18), the rate of change (second rate of change) of the amount of power supplied is made smaller than the first rate of change. be able to.

That is, the operation of controlling the rotation speed of the fan motor 15 by the blower control means 32 can precede the operation of controlling the opening of the proportional control valve 18 by the proportional valve control means 30.

In STEP 55, the set value of the variable timer T3 is set to a longer time as the correction value β of the energization amount to the fan motor 15 calculated by the energization amount calculation unit 36 is set longer. As the amount of current supplied to the burner 2 increases and the amount of combustion air supplied to the burner 2 recovers, the opening of the proportional control valve 18 can be adjusted. Therefore, the correction amount of the opening degree of the proportional control valve 18 can be reduced, and the combustion amount of the burner 2 can be prevented from being significantly reduced.

In step 72, similarly to step 55, by setting the set value of the variable timer T4 to a time longer than the set value (1 second) of the fixed timer T2, the rotation speed of the fan motor 15 by the blower control means 32 is set. Can be performed before the control operation of the opening degree of the proportional control valve 18 by the proportional valve control means 30.

Further, in STEP 72, the set value of the variable timer T4 is set to a longer time as the correction value β of the energization amount to the fan motor 15 calculated by the energization amount calculation section 36 is set longer. As the amount of current supplied to the burner 2 decreases and the amount of combustion air supplied to the burner 2 decreases, the opening of the proportional control valve 18 can be adjusted. Therefore, the correction amount of the opening degree of the proportional control valve 18 can be reduced, and the combustion amount of the burner 2 can be prevented from greatly increasing.

Next, a second embodiment of the present invention will be described.
This will be described with reference to FIGS. FIG. 6 is a control block diagram of a water heater as a combustion device of the second embodiment, and FIG. 7 is a control block diagram of a controller 8 provided in the water heater shown in FIG.

The water heater according to the second embodiment shown in FIG. 6 includes the water heater according to the first embodiment shown in FIG. 2, a method for detecting the supply amount of combustion air to the burner 2, and The control method of the rotation speed of the fan motor 15 is different.

Referring to FIG. 6, the water heater of the second embodiment does not have airflow sensor 16 provided in introduction path 12 of the water heater of the first embodiment, and has a fan motor. Rotational speed detecting means 24 for detecting the rotational speed of 15
And a current detecting means 25 for detecting the amount of current supplied to the fan motor 15.

When the amount of combustion air supplied to the burner 2 is reduced due to a blockage of the intake port 13 or the like, the amount of electricity supplied to the fan motor 15 required to rotate the fan 14 at a predetermined rotation speed is reduced. . That is, the rotation speed of the fan 14 (=
Fan motor 1 (rotational speed of fan motor 15)
The amount of electricity supplied to the burner 5 increases or decreases according to the increase or decrease of the combustion air to the burner 2.

As shown in FIG. 7, the air amount detecting means 70 provided in the controller 8 according to the second embodiment uses the relationship between the rotation speed of the fan 14 and the amount of electricity supplied to the fan motor 15. The amount of combustion air actually supplied to the burner 2 is detected.

Referring to FIG. 7, the controller 8 of the second embodiment is different from the controller 8 only in the configuration of the blower control means 32 in the first embodiment.
Is different from the embodiment. The ventilation control means 32 of the second embodiment includes a target air amount calculation unit 35, a target rotation speed calculation unit 7,
1, an electric current amount calculating unit 36, a current detecting unit 25, and an air amount detecting unit 70.

The target air amount calculating section 35 is a target value of the combustion air to be supplied to the burner 2 in accordance with the target combustion amount calculated by the target combustion amount calculating section 31 as in the first embodiment. Calculate the target air amount. The target rotation speed calculating unit 71 compares the target air amount with the amount of combustion air actually supplied to the burner 2 detected by the air amount detecting means 70, and sets a fan motor necessary for matching the two. 1
5 is calculated.

The energization amount calculation unit 36 adjusts the energization amount 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 detection means 24. As a result, similarly to the first embodiment, the amount of power to the fan motor 15 is adjusted so that the target air amount calculated by the target air amount calculation unit 35 is supplied to the burner 2.

The construction and operation of the proportional valve control means 30 are the same as in the first embodiment.

In the first and second embodiments, a water heater has been described as an example of a combustion device, but the present invention can be applied to other combustion equipment, 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 configuration diagram of a water heater that is a combustion device according to the first embodiment of the present invention.

FIG. 3 is a control 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;

FIG. 6 is a configuration diagram of a water heater that is a combustion device according to a second embodiment of the present invention.

FIG. 7 is a control block diagram of a controller provided in the water heater of FIG. 6;

[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 ... Air flow sensor, 17 ... Main solenoid valve, 18 ... Proportional control valve, 19 ... Flow sensor, 20 ...
Inlet water temperature sensor, 21 ... tap water temperature sensor, 22 ... temperature setting switch, 23 ... display, 24 ... rotational speed sensor, 25 ...
Current detection means, 30 proportional valve control means, 31 target combustion amount calculation unit, 32 blower control means, 33 change rate setting means, 34 adjustment stop means, 35 target air amount calculation unit, 3
6 ... energization amount calculation unit, 37 ... reference voltage calculation means, 38 ... comparison unit, 39 ... correction value calculation unit, 40 ... basic energization amount calculation unit,
41: energization amount determination unit, 70: air amount detection means, 71: target rotation speed calculation unit

Claims (5)

(57) [Claims] 1. A burner, a proportional control valve for adjusting a supply amount of fuel gas to the burner, a blower for adjusting a supply amount of combustion air to the burner, and a combustion air supplied to the burner Air flow rate detection means for detecting the flow rate of the air flow rate of the combustion air detected by the air flow rate detection means, the air flow control means for adjusting the rotation speed of the blower, so as to match a predetermined reference flow rate, A thermocouple that is installed facing the burner and generates a thermoelectromotive force according to an air ratio that is a ratio of an actual air amount supplied to the burner by the blower and an air amount required for combustion of the burner. The opening of the proportional control valve is adjusted by adjusting the rotation speed of the blower by the blower control means so that the thermoelectromotive force of the thermocouple matches a reference voltage corresponding to a predetermined reference air ratio. The first change, which is the rate of change of the rotation speed Combustion apparatus being characterized in that a proportional valve control means for adjusting the second rate of change is smaller than the rate. 2. A rate of change for setting the second rate of change to be smaller as the amount of adjustment of the rotation speed of the fan by the air blow control means required to make the air flow rate of the air blower equal to the reference flow rate is larger. The combustion device according to claim 1, further comprising a setting unit. 3. When the amount of adjustment of the rotation speed of the blower by the blower control means, which is necessary to make the blower amount of the blower coincide with the reference flow rate, is equal to or greater than a predetermined upper limit value.
The combustion device according to claim 1 or 2, further comprising an adjustment stopping unit that stops adjusting the opening of the proportional control valve by the proportional valve control unit. 4. The combustion apparatus according to claim 1, wherein said air amount detecting means is an air flow sensor. 5. The air amount detection means comprises: a rotation speed detection means for detecting a rotation speed of the blower; and a current detection means for detecting an amount of current supplied to the blower. The combustion apparatus according to any one of claims 1 to 3, wherein a flow rate of combustion air supplied to the burner is detected from a relationship with a current supply amount to the burner.