JPH08200660A - Combustion device - Google Patents

Abstract

PURPOSE: To increase an accuracy of an air volume control in a combustion equipment using a mass flow rate sensor. CONSTITUTION: An amount of air supplied from a combustion fan 5 for a combustion equipment to a burner is detected by a mass flow rate sensor. A target valve calculation part 27 calculates a target value Vp of an output of the mass flow rate sensor in reference to a supplied air temperature, a rotating amount of the combustion fan 5 and a predetermined calculation data. An operating amount correcting part 31 compares a detected output value VP' of an actual air volume of the mass flow rate sensor with the target value VP, and obtains a corrected amount of operating volume in such a manner that VP' may be coincided with VP. An air volume control part 26 corrects the operating volume so as to increase or decrease it with a corrected amount and then controls a rotation of the combustion fan 5 under the corrected operating amount.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burner combustion type combustion device such as a water heater and a bath kettle.

[0002]

2. Description of the Related Art FIG. 6 shows a schematic structure of a general water heater as a combustion device. In the figure, the instrument body 2 is housed in the instrument case 1. A burner 4 is installed below the combustion chamber 3 of the instrument body 2, and a combustion fan 5 for supply and exhaust is installed below the burner 4. A nozzle 6 is arranged opposite to the gas inlet of the burner 4, and fuel gas is supplied to the nozzle 6 via a gas supply passage 7. An electromagnetic valve 8 for opening and closing the passage and a proportional valve 10 for controlling the gas supply amount to the burner 4 by the opening amount are incorporated in the gas supply passage 7.

A passage 24 is formed by piping between the air chamber 9 below the burner 4 and the combustion chamber 3 above the burner. In this passage 24, a passage from the combustion fan 5 to the burner is formed. An air volume detection sensor 23 for detecting the air volume supplied to the air conditioner 4 is provided.

A hot water supply heat exchanger 11 is installed above the combustion chamber 3, and a water supply pipe 12 is provided at the inlet side of the hot water supply heat exchanger 11.
Is connected, and the hot water supply pipe 13 is provided on the outlet side of the hot water heat exchanger 11.
Is connected. The water supply pipe 12 is provided with a water inlet temperature sensor 14 for detecting the water supply temperature and a flow rate sensor 15 for detecting the water inlet flow rate, and a hot water outlet temperature sensor 16 for detecting the hot water supply temperature is provided on the hot water supply pipe 13 side. .

The combustion operation of this kind of equipment is carried out by a control device 17, which normally has a remote controller (not shown) for setting the hot water supply temperature and displaying the set temperature. ) Is connected.

In the figure, 18 is an igniter electrode for igniting fuel gas, 20 is a frame rod electrode for detecting the flame of the burner 4, and 21 is a fan rotation detection sensor such as a Hall IC for detecting the rotation of the combustion fan 5. Reference numeral 22 is a louver that functions as an intake port provided on the wall surface of the instrument case 1, and 19 is punching metal (provided as necessary) that equalizes the wind pressure toward the burner 4.

In this type of equipment, when a tap (not shown) provided at the tip of the hot water supply pipe 13 is opened, the water supply pipe 12
When the water flows in from the inside and the flow of the water is detected by the flow rate sensor 15, the controller 17 rotates the combustion fan 5, opens the solenoid valve 8 and the proportional valve 10, drives the igniter electrode 18, and ignites. I do. Then, after confirming that the flame rod electrode 20 has detected the flame, the valve opening drive current of the proportional valve 10 is controlled, and the gas supply amount (the opening amount of the proportional valve 10) is controlled so that the tapping temperature becomes the set temperature. Is controlled, and the rotation of the combustion fan 5 is controlled so as to supply the air corresponding to the gas supply amount.

FIG. 7 shows the relationship between the combustion control section 25 and the air flow rate control section 26 of the control device 17. The combustion control section 25 is detected by the feed water flow rate added from the flow rate sensor 15 and the incoming water temperature sensor 14. Based on the information on the hot water supply temperature, the hot water supply temperature detected by the hot water temperature sensor 16, and the set temperature added from the remote control, etc., the required combustion heat quantity is controlled by feedforward and feedback control so that the hot water temperature matches the set temperature. The (required gas supply amount) is obtained, and the valve opening drive current of the proportional valve 10 is controlled so as to obtain this required combustion heat quantity. On the other hand, the air volume control unit 26 obtains a target air volume corresponding to the required combustion heat quantity obtained by the combustion control unit 25, and the air volume detection sensor 23
The combustion fan 5 is rotationally controlled by using the fan rotation detection signal of the fan rotation detection sensor 21 so that the detected air volume detected in step S1 becomes the target air volume, and the air volume control of the air volume controller 26 and the combustion of the combustion controller 25 are performed. Combustion operation of equipment is performed by matching controls.

When the tap is closed after the use of hot water, the flow of water to the hot water supply heat exchanger 11 is stopped, and when the stop of the flow of water is detected by the signal from the flow rate sensor 15,
The electromagnetic valve 8 is closed, and after that, when the post-purge period during which the exhaust gas in the combustion chamber 3 is almost completely discharged has passed, the rotation of the combustion fan 5 is stopped and the next hot water is prepared.

[0010]

As described above, the combustion control unit 25 variably controls the valve opening amount (valve opening drive current) of the proportional valve 10, but controls the valve opening amount of the proportional valve 10. This is equivalent to controlling the gas ejection pressure of the nozzle 6 that ejects the fuel gas, more specifically, controlling the differential pressure between the pressure of the fuel gas from the proportional valve 10 to the nozzle 6 and the pressure in the combustion chamber 3. Yes, the combustion heat quantity control is performed by the gas pressure control system.
By using 23 as a differential pressure sensor (a sensor that detects the differential pressure between both ends of the passage 24 and measures the air volume), it is less susceptible to changes in the surrounding environment, and combustion control and air volume control are effectively matched. However, good combustion control can be performed.

However, the differential pressure sensor has a problem that the price is high and the device cost is high. In order to suppress such high costs, recently,
As the air volume detection sensor 23, a mass flow sensor (a specific example is a hot wire heater type air velocity sensor) is used. The mass flow rate sensor is much cheaper than the differential pressure sensor, and by using the mass flow rate sensor, the overall device cost can be reduced.

FIG. 5 is graph data obtained by the inventor's experiment by how the sensor output of the mass flow rate sensor fluctuates according to the change of the ambient temperature (the temperature of the blown air). In this experiment, the sensor output when the temperature was -20 ° C, 25 ° C, and 70 ° C was obtained in relation to the air volume, and the lower the temperature, the higher the sensor output. Therefore, when the air volume is optimally set at a certain temperature, if the temperature rises, the sensor output decreases, so the air volume control unit
No. 26 controls the combustion fan 5 in the direction of increasing the air volume so that the sensor output becomes the set value, so there is a problem that the air volume becomes excessive. Conversely, when the temperature drops, the air volume becomes the same. However, since the sensor output becomes high, the air volume control unit 26 controls the rotation of the combustion fan 5 so as to reduce the amount by which the sensor output becomes high. As a result, the air volume becomes insufficient. Occurs, and the amount of air commensurate with the amount of heat of combustion cannot be obtained, resulting in a problem that combustion performance deteriorates.

The present invention has been made to solve the above problems, and an object thereof is to perform accurate air volume control without being affected by temperature changes, even though an inexpensive mass flow sensor is used. It is to provide a combustion device capable of

[0014]

In order to achieve the above object, the present invention is constructed as follows. That is, the present invention, a burner that performs combustion, a combustion fan that supplies air to this burner, an air volume detection sensor that detects the air volume to the burner, and the rotation of the combustion fan based on the air volume detection signal of the air volume detection sensor. In a combustion device including an air volume control unit that controls by an operation amount, a supply air temperature sensor that directly or indirectly detects a supply air temperature by a combustion fan is provided, and the air flow detection sensor includes a mass flow sensor. A target value calculation unit that obtains an output target value of the mass flow rate sensor using the operation amount of the combustion fan rotation, the temperature detected by the supply air temperature sensor, and previously calculated data, and a sensor output value of the mass flow rate sensor and the target Operation amount correction that variably adjusts the fan operation amount so that the sensor output value matches the output target value by comparing it with the output target value calculated by the value calculator Bets are configured as being provided.

Further, a heat exchanger heated by the flame of the burner, a water supply pipe for supplying water to the heat exchanger, and an inlet water temperature sensor provided on the water supply pipe for detecting a water supply temperature are provided. The entry water temperature sensor also serves as the supply air temperature sensor, and may be provided with a temperature conversion unit that converts the supplied water detection temperature of the input water temperature sensor into the supply air temperature based on the correlation data of the water temperature and the air temperature given in advance. It is a characteristic configuration of the present invention.

[0016]

In the present invention having the above structure, the mass air flow sensor detects the air flow rate supplied to the burner by the combustion fan. Although this detected air volume changes depending on the ambient temperature change, in the present invention, the target value of the sensor output that is not affected by the temperature change is obtained by the detected temperature, the operation amount of the combustion fan rotation, and the previously calculated data. , The operation amount is corrected to match the output target value and the air volume is controlled, so that the air volume does not become excessive or insufficient due to temperature change and is not affected by temperature change. No suitable air flow control is achieved.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same names as those in the conventional example are designated by the same reference numerals, and the duplicate description thereof will be omitted. The combustion equipment of the present embodiment is intended for a water heater similar to that shown in FIG. 6, and the characteristic of the present embodiment is that, as shown in FIG. 1, the controller 17 controls the combustion amount and the air flow amount. 6 is provided with a target value calculation unit 27 and a manipulated variable correction unit 31.
Supply temperature sensor such as a thermistor that detects the ambient air temperature (blast air temperature) in the instrument case 1 of the combustion equipment shown in
28 is provided, and the other configuration is the same as the conventional example. The air volume detection sensor 23 for detecting the air volume supplied from the combustion fan 5 to the burner 4 is composed of a mass flow rate sensor (heat wire heater type air velocity sensor).

The target value calculation unit 27 has a built-in memory, which stores the output target value of the mass flow rate sensor based on the detected temperature of the intake air temperature sensor and the operation amount (control amount) of the combustion fan 5. The calculation data for obtaining is given. In the present embodiment, this calculation data is created based on the experimental flow graph data of the mass flow rate sensor with the temperature as a parameter and the air flow and the sensor output shown in FIG.

In this experimental graph data, 0% of the operation amount range on the horizontal axis is the value of the air volume when the combustion equipment has the minimum combustion heat quantity (minimum combustion capacity), in other words, the combustion fan 5 corresponding to the minimum combustion heat quantity. It means the rotation speed, and 100% of the manipulated variable range means the air volume (fan rotation speed) corresponding to the maximum combustion heat quantity (maximum combustion capacity) of the combustion equipment. That is, as the combustion control unit 25 controls the combustion amount within the range of the maximum combustion heat amount and the maximum combustion heat amount, the air flow control unit 26 controls the fan rotation speed operation amount (control amount) within the operation amount range of 0% to 100%. ) Control.

In the experimental graph of FIG. 5, data of -20 ° C. and 70 ° C. with a temperature difference of 45 ° C. above and below the data of 25 ° C. are obtained. Based on the ℃ data, both -20 ℃ data and 70 ℃ data have the same fluctuation range of ΔV ₁ (specifically, 0.1 V). Based on the data of, both -20 ℃ and 70 ℃ data are both ΔV ₂ (specifically 0.2
V) has the same fluctuation range, and these fluctuation ranges change from 100% manipulated variable to 0% manipulated variable, with the same fluctuations at -20 ° C and 70 ° C based on the 25 ° C data. The width increases linearly.

From this experimental data, the sensor output of 25 ° C.
The absolute value of the fluctuation range is based on the data
When the horizontal axis (X axis) is represented by the operation amount, the graph of the variation amount of the sensor output with respect to the operation amount as shown in FIG. 3 is obtained. From this graph, the sensor output variation width Y with respect to the operation amount X is obtained. The following equation (1) can be obtained by obtaining the relationship.

[0022] Y = f (X) = - (ΔV 1/100) X + ΔV 2 ····· (1)

Specifically, in the above formula (1), ΔV ₁ is 0.
1 and ΔV ₂ has a value of 0.2. The fluctuation range of this sensor output is the data of the temperature difference of 45 ° C with respect to the reference temperature of 25 ° C. Therefore, the fluctuation range of the sensor output when the unit temperature (1 ° C) changes based on the 25 ° C data. Is (1)
It is obtained by dividing the equation by the temperature difference of 45. Therefore, by multiplying the fluctuation range of the sensor output per unit temperature by the temperature difference with respect to the reference temperature of 25 ° C, and adding this value to the target value of the sensor output corresponding to the reference temperature of 25 ° C, at any detected temperature The target value of the sensor output is obtained. If this is expressed in an equation, it becomes equation (2).

V _P = V ₂₅ + {f (X) / 45} × (25−T) (2)

However, V _P is the sensor output target value at any detected temperature detected in the temperature range of −20 ° C. to 70 ° C., V ₂₅
Is the target value of the sensor output at 25 ° C., X is the operation amount (%) of fan rotation control, and T is the detected temperature (air temperature) ° C. If this is shown more concretely, equation (3) is obtained.

V _P = V ₂₅ + {((-0.1 / 100) X + 0.2) / 45} (25-T) (3)

In the present embodiment, this equation (3) is stored as calculation data in the memory of the target value calculation unit 27, and the target value calculation unit 27 controls the detected temperature T detected by the supply air temperature sensor and the air volume control. Using the fan rotation operation amount X of the unit 26, the target value V _P of the sensor output that should be originally output by the mass flow rate sensor is calculated based on the equation (3) stored in the memory, and this calculated value V _P is added to the manipulated variable correction unit 31.

The manipulated variable correcting unit 31 compares the sensor output value (measured air volume value) V _P ′ of the mass flow rate sensor with the sensor output target value V _P obtained by the target value calculating unit 27, and the two match. If not, the correction amount of the operation amount is obtained in the direction in which the sensor output value matches the target sensor output value. That is,
When V _P ′> V _P , the operation amount is reduced.
When V _P ′ <V _P , the positive and negative signs of the correction amount are set in the direction of increasing the operation amount, but the correction amount value (absolute value) is a constant value regardless of the magnitude of V _P ′ and V _P. The operation amount may be changed stepwise every time it is set and corrected, or the correction amount corresponding to the difference between V _P ′ and V _P may be obtained by proportional calculation. The calculated correction amount is added to the air volume control unit 26.

The air volume control unit 26 increases / decreases and corrects the operation amount of the combustion fan control according to the correction amount added from the operation amount correction unit 31, and controls the rotation of the combustion fan 5 so as to supply the optimum air amount corresponding to the combustion heat amount.

According to the present embodiment, even if the air flow detection value of the mass flow sensor changes due to the change in environmental temperature,
The deviation of the operation amount of the fan rotation control due to the sensor output fluctuation is corrected by the operation amount correction unit 31, and the optimum air amount is supplied to the burner 4 regardless of the temperature change, and the accuracy of the air amount control is improved. It is dramatically improved, and good combustion performance can be obtained, which is comparable to the case where an expensive differential pressure sensor is used.

FIG. 2 is a block diagram showing the main structure of another embodiment of the present invention. In this embodiment, the incoming water temperature sensor 14 also serves as a supply air temperature sensor, and for that purpose, a temperature conversion unit 30 for converting the incoming water temperature detected by the incoming water temperature sensor 14 into an air temperature is provided. . The temperature conversion unit 30 has a built-in memory, and the correlation data of water temperature and air temperature as shown in FIG. 4 is stored in this memory. The data in Fig. 4 is the data obtained over a long period (1 year in the case of this data) of how the water temperature in a large-volume tank such as a water purification plant changes with temperature, and its graph As is clear from the above, the water temperature and the air temperature have a linear relationship, and by previously obtaining and giving an arithmetic expression of a straight line for converting the water temperature into the air temperature, by using this arithmetic expression,
The temperature can be calculated from the water temperature.

In this embodiment, the relationship between the temperature T and the water temperature T _W is given by the equation (4) based on the data shown in FIG.

T = AT _W + B (4)

In this embodiment, the arithmetic expression (4) is stored in the memory of the temperature conversion unit 30. In the equation (4), A and B are constants, and from the graph data of FIG. 4, A = 1.4,
B = -5.4.

The temperature conversion unit 30 receives the feed water temperature detected from the incoming water temperature sensor 14, and uses this feed water temperature T _W to obtain the temperature T using the arithmetic expression (4) stored in the memory. The calculated value is added to the target value calculation unit 27. The target value calculation unit 27 corrects the air volume fluctuation (manipulation amount fluctuation) associated with the output fluctuation due to the temperature of the mass flow rate sensor, based on the air supply temperature obtained from the water supply temperature, as in the embodiment shown in FIG. As a result, it becomes possible to control the air flow rate with high accuracy as in the embodiment shown in FIG. 1 and achieve good control of the combustion operation.

Further, in this embodiment, since the incoming water temperature sensor 14 used as an indispensable sensor for the water heater is also used as the incoming water temperature sensor 28, it is not necessary to separately provide the intake air temperature sensor 28. Therefore, it is possible to simplify the device configuration and reduce the cost. According to the test data in FIG. 4, the error when converting the water temperature into the air temperature is ± 2 ° C.
It has been proved that the function of the supply air temperature sensor 28 can be fully substituted by the incoming water temperature sensor 14.

The present invention is not limited to the above-mentioned embodiments, and various embodiments can be adopted. For example, in each of the above-described embodiments, the mass flow rate sensor is constituted by a hot wire heater type wind speed sensor, but various other known mass flow rate sensors may be used.

In each of the above embodiments, the target value calculation unit 27
Although the operation data given to the above is given in the form of the operation formula, this may be given in the form of table data. Similarly, in the embodiment of FIG. 2, the temperature conversion data given to the temperature conversion unit 30 is given in the form of an arithmetic expression, but this may also be given as table data of water temperature and air temperature.

Furthermore, in each of the above-mentioned embodiments, a single-function water heater (a water heater having only a hot water supply function) has been described as an example of the combustion equipment. The present invention is applied to a combined water heater having both functions such as heating, and other various types of combustion equipment such as a burner combustion type bath heater, heater, air conditioner, air conditioner, air conditioner, and the like.

[0040]

According to the present invention, based on the detected temperature of the air supply temperature sensor, the deviation of the air flow (fan rotation operation amount) caused by the temperature characteristic of the air flow detection value of the mass flow sensor is given in advance by using the calculated data. Since it is configured to correct, it is possible to improve the accuracy of air volume control by eliminating the influence of variation in air volume detection variation due to temperature, and good combustion comparable to that using an expensive differential pressure type sensor. It is possible to obtain performance.

Further, in the structure in which the inlet water temperature sensor of the combustion equipment is also used as the supply air temperature sensor, the supply air temperature sensor can be omitted, so that the structure of the device is further simplified and the cost of the device is reduced. Can be realized.

[Brief description of drawings]

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

FIG. 2 is a block configuration diagram of a main part showing another embodiment of the present invention.

FIG. 3 is a graph showing a relationship between a manipulated variable of a combustion fan and a fluctuation range with respect to reference temperature data of a mass flow sensor.

FIG. 4 is an explanatory diagram of conversion data of water temperature and air temperature.

FIG. 5 is a graph showing variation variation of the mass flow rate sensor depending on temperature.

FIG. 6 is a schematic configuration diagram of a general water heater as a combustion device.

FIG. 7 is a block diagram showing a related configuration of a combustion control unit and a control unit of an air volume control unit of a conventional water heater.

[Explanation of symbols]

 5 Combustion fan 25 Combustion control unit 26 Air volume control unit 27 Target value calculation unit 31 Manipulation amount correction unit

Claims (2)

[Claims] 1. A burner that burns, a combustion fan that supplies air to the burner, an air volume detection sensor that detects the air volume to the burner, and the rotation of the combustion fan is operated based on the air volume detection signal of the air volume detection sensor. In a combustion device having an air volume control unit that controls the air volume, a supply air temperature sensor that directly or indirectly detects a supply air temperature by a combustion fan is provided, and the air volume detection sensor is configured by a mass flow rate sensor, A target value calculation unit that obtains an output target value of the mass flow rate sensor by using the operation amount of the combustion fan rotation, the temperature detected by the supply air temperature sensor, and calculation data that is given in advance;
An operation amount correction unit that variably adjusts the operation amount of the fan rotation so that the sensor output value of the mass flow rate sensor and the output target value obtained by the target value calculation unit are compared and the sensor output value matches the output target value. Combustion equipment equipped with. 2. A heat exchanger heated by the flame of a burner, a water supply pipe for supplying water to the heat exchanger, and an inlet water temperature sensor provided on the water supply pipe for detecting a water supply temperature. The water temperature sensor also serves as the air supply temperature sensor,
The combustion device according to claim 1, further comprising a temperature conversion unit configured to convert the feedwater detection temperature of the water temperature sensor into a supply air temperature and output the temperature based on preliminarily given correlation data between the water temperature and the air temperature.