JP2808852B2 - Combustion control device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a combustion 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 a stage subsequent to the combustion amount control valve 8 and is connected to the auxiliary valves 9 and 9.
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 includes a first arithmetic unit 22 as a deviation calculating unit.
Temperature data from the thermistor 4 calculated in (° C)
Proportional integral control amount based on the deviation e between
Outputs Up (Kcal / sec). Then, the feedforward control amount and the proportional integrated control amount are added by the second arithmetic unit 25, and the added value is converted into a current value signal,
The heat is supplied to the combustion amount control valve 8, whereby the combustion in the heat exchanger 1 is performed.

(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. The set temperature is set more accurately than in the case of
And there is a problem that the response is poor at the start of operation or when there is a large fluctuation in the input temperature. For example, it is conceivable to improve 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 both the settling property and the responsiveness well.

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 invention of claim (1), the combustion control device supplies gas to a heat exchanger and a combustion part of the heat exchanger. A gas supply path, a combustion amount control valve provided in the gas supply path, temperature detection means for detecting a tapping temperature of the heat exchanger, and calculating a deviation between a set temperature and a detection temperature obtained from the temperature detection means. A fuzzy inference means for inputting the deviation obtained from the deviation calculation means and outputting a fuzzy inference control amount for combustion by using the deviation obtained from the deviation calculation means, and a combustion based on the calculation based on the deviation obtained from the deviation calculation means. A proportional control amount output means for outputting a proportional control amount, the fuzzy inference control amount and the proportional control amount, and the proportional control amount is output at a high rate near the set temperature, and the set temperature is output. Output ratio control means for outputting a fuzzy inference control amount at a large rate in a far region, and valve control means for operating the combustion amount control valve based on an addition control amount of each control amount obtained from each of the output ratio control means And a configuration consisting of

Further, in the invention of claim (2), the output ratio control means determines the output ratio based on the ZR suitability of the deviation used when the fuzzy inference means performs fuzzy inference.

(Operation) According to the configuration of the invention of claim (1), addition control of the proportional control amount output at a large ratio near the set temperature and the fuzzy inference control amount output at a large ratio near the set temperature. The combustion amount control valve is actuated based on the amount to burn the combustion portion of the heat exchanger.

Further, according to the configuration of the invention of claim (2), in the configuration of claim (1), the output ratio of the output ratio control means is determined based on the ZR conformity of the deviation used in fuzzy inference. .

(Example) Hereinafter, an example 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 in that the operation control unit 12 obtains the combustion amount at the time of controlling the combustion amount control valve 8 by fuzzy inference control in addition to the proportional control. The control system diagram of FIG. It will be described with reference to FIG. In addition,
The operation control unit 12 is actually configured by a microcomputer including a CPU, a ROM, a RAM, and the like, and its operation is performed by software processing, and the operation control unit 12 also functions as a valve control unit.

In the present invention, in the operation control unit 12, in addition to the feedforward control amount output unit 20 and the proportional integral control amount output unit 21 as the proportional control amount output unit, a fuzzy inference control amount output unit 30 as fuzzy inference unit is further provided. In addition, the fuzzy inference control amount output unit 30 and the proportional integral control amount output unit 21 are respectively provided with effective ratio output units 33, 33 as output ratio control means at the subsequent stage.

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 the proportional integral control amount Up and the fuzzy inference control amount Uu of the ratio based on the α are output (step 8), respectively, 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, NL to PS, are set for the water volume 1 as another antecedent variable, and each of these labels has a membership function as shown in FIG. 4 (B).

Seven labels from NL to PL are set for the combustion amount Kcal as a consequent variable, 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). ). Now, for example, "+30
° C ”is given as“ 16 ”as the amount of water, and 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
In e = PL, l = NS then Kcal = PL], the antecedent part conformance is [0.5], which is smaller among [0.7] and [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, l = 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 the multiplication is similarly performed 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.

In this way, the effective ratio output units 33, 33 are provided and the proportional integral control amount and the fuzzy inference control amount are given at a predetermined ratio according to the ratio of the deviation, because the fuzzy inference control is performed 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.

As described above, if the ZR suitability of the deviation used for fuzzy inference is used as “α”, the trouble of separately obtaining “α” is omitted.

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 proportional-integral control amount output unit 21 is used as the proportional-control amount output unit. However, the proportional-control amount output unit may perform only the proportional (P) control, or may perform the proportional-integral differential (PID) control. May be performed.

(Effects of the Invention) As is apparent from the above description, according to the present invention, control is performed mainly by proportional control having excellent settling characteristics near the set temperature, and response characteristics are mainly obtained in the far range of the set temperature. Control is performed by excellent fuzzy inference control, so that good response can be exhibited even at the start of combustion or when there is a large fluctuation in input temperature. As a result, both settling and response are always A well maintained combustion control device is obtained.

In addition, since the output ratio of the output ratio control means is determined based on the ZR suitability of the deviation used in fuzzy inference, a combustion control device that can operate quickly with a simple configuration is obtained. Can be

[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 thereto. 1 ... heat exchanger 4 ... thermistor (temperature detecting means) 5 ... gas burner (combustion part) 6 ... gas supply path 12 ... operation control part (valve control means) 21 ... proportional integration Control amount output section (proportional control amount output means), 22 first arithmetic section (deviation calculating means), 30 fuzzy inference control amount output section (fuzzy inference means), 33 effective ratio output section (output ratio) Control means).

Claims (2)

(57) [Claims] 1. A heat exchanger (1); a gas supply path (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 (30) which receives the deviation obtained from the deviation calculation means (22) as an input and outputs a fuzzy inference control amount for combustion and outputs a fuzzy inference control amount; and a deviation obtained from the deviation calculation means (22). A proportional control amount output means (21) for outputting a proportional control amount for combustion by an operation based on the fuzzy inference control amount and the proportional control amount, and outputting the proportional control amount at a large rate near the set temperature. Let
Output ratio control means (33) (33) for outputting the fuzzy inference control amount at a large ratio in the set temperature distant range, and addition control of each control amount obtained from each of the output ratio control means (33) (33) And a valve control means (12) for operating the combustion amount control valve (8) based on the amount. 2. The output ratio control means (33) (33) determines an output ratio based on the ZR conformity of a deviation used when the fuzzy inference means performs fuzzy inference.
Combustion control device.