JP2855815B2 - Combustion control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel control device used in a water heater or the like.

(Prior Art) FIG. 6 shows a basic configuration of a water heater provided with a combustion control device according to the present invention.

In the figure, reference numeral 1 denotes a heat exchanger, a circulation pipe 2 is meanderingly arranged in the heat exchanger 1, a water amount detector 3 is provided on an inlet side of the circulation pipe 2, and a tapping temperature is detected on a tapping side. A thermistor 4 is provided as temperature detecting means for detecting. Gas burners 5, 5 as a pair of combustion units are provided at a lower portion in the heat exchanger 1, and the gas burners 5, 5 are provided.
Is connected to a gas supply path 6 from outside. 5a and 5a are gas burner igniters. The gas supply path 6 is provided with a main valve 7, a combustion amount control valve 8, and auxiliary valves 9 and 9 from the outside. The gas supply path 6 branches at the subsequent stage of the combustion amount control valve 8 and
Lead to each. This water heater is configured such that one or two gas burners 5, 5 can be selectively used in accordance with the amount of hot water supply by selectively opening and closing the auxiliary valves 9, 9 as appropriate. Reference numeral 10 denotes a fan motor for supplying combustion air to the gas burners 5,5.

Reference numeral 12 denotes an operation control unit of the water heater, which gives an operation signal for appropriately operating the main valve 7, the auxiliary valves 9, 9 and the igniters 5a, 5a when an operation command is given, and a water amount detector 3, a thermistor. 4, a combustion amount control valve 8 and a fan motor
It is provided to give an operation control signal to 10.

With reference to the control system diagram of FIG. 7, an example of control operation of the combustion amount of the water heater will be described.

Reference numeral 20 denotes a feedforward (FF) control amount output unit, and reference numeral 21 denotes a proportional-integral (PI) control amount output unit, both provided in the operation control unit 12. The feedforward control amount output unit 20 outputs a feedforward control amount Uf (Kcal / sec) based on the water amount data (/ min) from the water amount detector 3 and the set temperature data (° C). On the other hand, the proportional-integral control amount output unit 21 is provided with a first calculating unit as a deviation calculating unit.
The proportional integral control amount Up (Kcal / sec) is output based on the deviation e between the detected temperature data (° C.) from the thermistor 4 calculated at 22 and the set temperature data. And a second arithmetic unit
At 25, the feedforward control amount and the comparison integrated control amount are added, and the added value is converted into a current signal and given to the combustion amount control valve 8, whereby the heat exchanger 1
Combustion is taking place.

(Problems to be Solved by the Invention) FIG. 8 shows an example of a change in the amount of current supplied to the control valve 8 based on the above-described control operation and a rise in the tapping temperature corresponding to the change. Although the set temperature is set more accurately than in the case of the above, it takes a long time to settle, and there is a problem that the responsiveness at the start of operation or when there is a large fluctuation in the input temperature is poor. . For example, it is conceivable to increase the responsiveness by changing the constant used in the proportional integral control in accordance with the amount of water or the like, but it has been difficult to maintain good responsiveness based on the settling property and the responsiveness. .

The present invention has been made in view of such a problem, and an object of the present invention is to provide a combustion control device in which stabilization and responsiveness in control of tapping temperature are always maintained satisfactorily.

(Means for Solving the Problems) In order to achieve such an object, in the present invention, a combustion control device includes a heat exchanger, a gas supply unit that supplies gas to a combustion unit of the heat exchanger, A combustion amount control valve provided in the gas supply path, a temperature detection unit that detects a tapping temperature of the heat exchanger, and a deviation calculation unit that calculates a deviation between a set temperature and a detection temperature obtained from the temperature detection unit. Fuzzy inference means for inputting the deviation obtained from the deviation calculation means and fuzzy inferring the combustion amount and outputting the output; and proportional integration control amount output means for inputting the deviation obtained from the deviation calculation means and outputting a proportional integral control amount. Effective ratio output means for outputting the combustion amount obtained from the fuzzy inference means and the proportional integral control amount obtained from the proportional integral control amount output means at a predetermined ratio according to the deviation; Valve control means for operating the combustion amount control valve based on the output of the effective ratio output means.

(Operation) According to the above configuration, the combustion amount is fuzzy inferred by the fuzzy inference means using the deviation between the set temperature and the detected temperature obtained from the deviation calculation means as input, while the proportional integral control amount output means is input using the deviation as input. The proportional integral control amount is output from the control unit, and the effective amount output means outputs the combustion amount and the proportional control control at a predetermined ratio according to the deviation. Based on the output, the combustion amount control valve is operated, and the combustion unit of the heat exchanger is operated. Is performed.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The basic configuration of the combustion control device of the present invention is the same as that of the conventional one shown in FIG. 6, and a description thereof will be omitted.

The present invention is characterized by a configuration in which the operation control unit 12 fuzzy infers a combustion amount when controlling the combustion control valve 8, and the configuration will be described with reference to a control system diagram of FIG. Note that the operation control unit 12 is actually
The operation is performed by software processing, and the operation control unit 12 also functions as a valve control unit.

In the present invention, the operation control unit 12 further includes a fuzzy inference control amount output unit 30 as fuzzy inference means in addition to the feedforward control amount output unit 20 and the proportional integral control amount output unit 21. Effective ratio output units 33, 33 are provided at the subsequent stages of the quantity output unit 30 and the proportional-integral control amount output unit 21, respectively.

The fuzzy inference control amount output unit 30 is provided to output a fuzzy inference control amount (Kcal / sec) based on the water amount data from the water amount detection unit 3 and the deviation from the first calculation unit 22. Each of the effective ratio output units 33 outputs the control amount output from the proportional integrated control amount output unit 21 and the fuzzy inference control amount output unit 30 at each ratio where their respective sums are “1”. Set the integral control output to “α”
In this case, the output of the fuzzy inference control amount is “1−α”. As the “α”, a ZR conformity of a deviation described later is adopted.

The combustion control operation of the operation control unit 12 will be described with reference to the flowchart of FIG.

First, the water amount data from the water amount detector 3 and the thermistor 4
Is supplied (step 1), the deviation between the detected temperature and the set temperature is calculated (step 2). Then, the feedforward control amount Uf is output based on the water amount and the set temperature (step 3), the proportional integral control amount Up is output based on the deviation (step 4), and the fuzzy inference control amount Uu is output based on the water amount and the deviation (step 5). Next, the ZR conformity α of the deviation is calculated (step 6), and a proportional integral control amount Up and a fuzzy inference control amount Uu at a ratio based on the α are output (step 8), and the feed is calculated. The proportional integral control amount and the fuzzy inference control amount are added to the forward control amount, the current value is converted from the added control amount (step 9), and the current value signal is output to the combustion amount control valve 8 (step 9). Step 10), and return to step 1.

By repeatedly performing the operations of Step 1 to Step 10, the combustion control corresponding to the change between the water amount and the tapping temperature is performed, and the tapping temperature is settled to the set temperature.

Next, the fuzzy inference operation of the fuzzy inference control amount output unit 30 will be described.

FIG. 3 shows an example of a fuzzy rule. Five labels from NL to PL are set for the temperature deviation e as one of the antecedent variables, and each label is a member as shown in FIG. 4 (A). Has a ship function. Four labels from NL to PS are set for the water quantity as another antecedent variable, and each of these labels has a membership function as shown in FIG. 4 (B).

The combustion amount Kcal as a consequent variable is set at seven levels from NL to PL, and each of these labels has a membership function value as shown in FIG. 4 (C).

Then, for example, when the temperature deviation and the water amount are given, the antecedent part conformity for each label is calculated in the corresponding rule, and the smallest value is selected as the antecedent part conformity for each rule (MIN calculation). ). Hereinafter, for example, as the deviation “+3
If 0 ° C ”is given as“ 16 ”as the amount of water, the deviation is the conformity [0.5] [1.0] in the labels ZR, PS, and PL.
Each [0.7] is calculated, and on the other hand, as the amount of water, the conformity [1.0] [1.0] [0.5] in the labels ZR, PS, and NS
Each is calculated. Then, for example, the rule [if e
= PL, = NS then, Kcal = PL], the antecedent part conformance is [0.5], which is smaller than [0.7] [0.5].

Next, each antecedent part fitness in each of the above rules is multiplied by the membership function value of the corresponding consequent part variable label, and the sum of all the multiplied values is the total value of the antecedent part fitness. Is divided by (MAX operation) to calculate the control amount. For example, the rule [if e
= PL, = NS then Kcal = PL], the consequent part function value [1.650] of the PL label is multiplied by the antecedent part fitness [0.5], and similarly multiplied in other rules,
The added value is divided by the total value of all the antecedent parts conformity such as the above [0.5].

The fuzzy inference control amount obtained in this manner is output at the output ratio (1-α) defined by the effective ratio output unit 33. As the “α”, the ZR conformity of the deviation is adopted as described above. I have. For example, when the deviation is 30 ° C. as described above, α is [0.5], the fuzzy inference control amount is output at a rate of [1-0.5 = 0.5], and the proportional integral control amount is also [0.5]. ] Is output.

Providing the effective ratio output units 33 and 33 and providing the proportional integral control amount and the fuzzy inference control amount at a predetermined rate according to the degree of the deviation in the fuzzy inference control at a position away from the set temperature where the deviation is large. Since the response is good and the deviation of the proportional integral control is good at a position close to the set temperature where the deviation is small, the advantages of the respective control characteristics are used more effectively.

FIG. 5 shows an example of a change in the amount of current supplied to the control valve 8 based on the above-described control operation and a rise in the tapping temperature corresponding to the change.
Responsiveness improved.

In the above embodiment, the feedforward control amount output unit
20 is used together, but the fuzzy inference control amount output unit
It is also possible to adopt a configuration in which control is performed only by the outputs of the proportional-integral control-amount output unit 21 and 30.

(Effect of the Invention) As is apparent from the above description, according to the present invention, the fuzzy inferred combustion amount and the proportional integral control amount
The output is output at a predetermined ratio according to the deviation, and the combustion control is performed based on the ratio.When the deviation is large, the ratio of fuzzy inference control with good response is large, and when the deviation is small, proportional integral control with good settling is provided. As a result, the advantages of the respective control characteristics of fuzzy inference control and proportional integration control can be effectively used, and as a result, a combustion control device in which both settling and responsiveness are always well maintained. Is obtained.

[Brief description of the drawings]

1 to 5 relate to an embodiment of the present invention, FIG. 1 is a control system diagram according to the embodiment of the present invention, FIG. 2 is a flowchart for explaining the operation, and FIG. 3 is a rule used for fuzzy inference. FIGS. 4 (A), 4 (B), and 4 (C) show membership functions used for fuzzy inference, and FIG. 5 shows changes in the amount of current supplied to the control valve based on the control operation and the corresponding changes. It is a graph which shows the rising example of a tapping temperature. 6 to 8 relate to a conventional example, FIG. 6 is a configuration diagram showing a basic configuration of a water heater provided with a combustion control device, FIG. 7 is a control system diagram, and FIG. 8 is a control valve based on a control operation. FIG. 7 is a graph showing an example of a change in the amount of current given to the heater and a rise in the tapping temperature corresponding to the change. DESCRIPTION OF SYMBOLS 1 ... Heat exchanger 4 ... Thermistor (temperature detection means) 5 ... Gas burner (combustion part) 6 ... Gas supply path 12 ... Operation control part (valve control means) 22 ... First Arithmetic unit (deviation calculating means), 30... Fuzzy inference control amount output unit (fuzzy inference means).

Claims (1)

(57) [Claims] 1. A heat exchanger (1), a gas supply section (6) for supplying gas to a combustion section (5) of the heat exchanger (1), and a combustion provided in the gas supply path (6). Quantity control valve (8)
Temperature detecting means (4) for detecting a tapping temperature of the heat exchanger (1); deviation calculating means (22) for calculating a deviation between a set temperature and a detected temperature obtained from the temperature detecting means (4). Fuzzy inference means (3) for inputting the deviation obtained from the deviation calculation means (22) as an input and fuzzy inferring and outputting the combustion amount;
0), and a proportional-integral control amount output means (21) which receives the deviation obtained from the deviation calculation means (22) as an input and outputs a proportional-integral control amount.
Effective ratio output means for outputting the combustion amount obtained from the fuzzy inference means (30) and the proportional integral control amount obtained from the proportional integral control amount output means (21) at a predetermined ratio according to the deviation. (33) and a valve control means (12) for operating the combustion amount control valve (8) based on the output of the effective ratio output means (33).