JPH04240360A - Controller for absorption type refrigerator - Google Patents

Abstract

PURPOSE:To automatically alter a set value of a chilled water outlet temperature and to improve operability by so setting a fuzzy rule and a membership function as to alter a set temperature by using the outer environmental temperature of a refrigerator so as to control the heating amount of a generator according to external conditions. CONSTITUTION:In an absorption type refrigerator, a chilled water outlet temperature detector 24 is provided, and its output signal is input to a controller 23. The controller 23 has an MPU 25 including a fuzzy inference processor 27 and a control rule memory 28, and a controller 26 of a fuel control valve 17. The memory 28 stores a control rule necessary for a fuzzy logical calculation, a condition unit and an conclusion unit membership function. When the MPU 26 inputs external conditions such as deviations of the set values of the chilled water inlet temperature and chilled water outlet temperature, a change rate, etc., as input variables, and performs a fuzzy control, a fuzzy rule for altering the set temperature by using the conditions and a membership function are set.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an absorption refrigerating machine control device which controls an absorption refrigerating machine using fuzzy control.

0002

2. Description of the Related Art Conventionally, various devices have been considered for performing fuzzy control using physical quantities representing various external conditions and internal conditions. For example, in the case of an absorption chiller/heater or an absorption chiller, in addition to multiple external conditions such as the deviation and rate of change of the chilled water outlet temperature from the set value, and the deviation and rate of change of the chilled water inlet temperature, the high temperature regenerator Fuzzy control is performed by simultaneously incorporating multiple internal conditions as input variables, such as the rate of change in temperature and the rate of change in circulation pump drive frequency.

[0003] In such devices, fuzzy rules (
When creating rules (hereinafter referred to as rules), they are described using so-called production rules (IF~THEN rules). Some input variables (membership functions) are incorporated into fuzzy inference alone, but in many cases is ANDed with other input variables to perform fuzzy inference. For example, if the input variables are A, B, and C and the output variable is D, Rule 1: IF A is PB AND B is Z
RANDC is NB THEN Dis is ZR (However, PB is positively large, ZR is zero, and NB is negatively large. The deviation of the chilled water outlet temperature from the set value is often used to control the fuel supply to the evaporator.

However, depending on the environment in which the refrigerator is actually used (changes in temperature such as summer and winter), it becomes necessary to change the set temperature for each user. For this reason, the settings and the like have been manually performed by scheduling (determining the set temperature, operating time, etc. during operation) from a central monitoring board.

[0005]

[Problems to be Solved by the Invention] As described above, the set value of the cold water outlet temperature must be changed manually depending on the season, and the control is troublesome.

[0006]

[Means for Solving the Problems] The present invention has been made in view of the above points, and consists of forming a refrigeration cycle by connecting an evaporator, an absorber, a generator, a condenser, etc. In a control device for an absorption chiller that controls the heating amount of the generator according to external conditions, a fuzzy rule and a membership function are set to change the set temperature using the external environmental temperature of the chiller. There is.

[0007]

[Operation] According to the present invention, the cold water outlet temperature setting is determined by performing fuzzy reasoning on the basis of information on the outside temperature to change the seasonal setting schedule, which has conventionally been determined based on human know-how.

[0008]

[Example] Fig. 1 shows a dual-effect absorption refrigerator using water as a refrigerant and a lithium bromide (LiBr) aqueous solution as an absorbent (solution), and 1 is a high temperature generator equipped with a burner 1B; 2 is a low temperature generator, 3 is a condenser, 4 is an evaporator, 5 is an absorber, 6
1 is an absorption liquid pump, 7 and 8 are a low temperature heat exchanger and a high temperature heat exchanger, respectively, 10 is a dilute absorption liquid pipe, 11 is an intermediate absorption liquid pipe, 12 is a concentrated liquid pipe, 13 is a refrigerant pipe, and 14 is a refrigerant liquid flow down. The pipes 15 are refrigerant liquid circulation pipes, and each pipe is connected as shown in FIG. And the refrigerant liquid circulation pipe 1
A refrigerant pump 15P is provided in the middle of 5. Also,
16 is a fuel supply pipe connected to the burner 1B, and a fuel control valve (heat amount control valve) 1 is installed in the middle of this fuel supply pipe 16.
7 is provided. Further, 20 is a cold water pipe, and an evaporator heat exchanger 21 is provided in the middle of this cold water pipe 20. Furthermore, 22 is a cooling water pipe.

Reference numeral 23 denotes a control section, and 24 denotes a cold water outlet temperature detector provided in the cold water pipe 20. This cold water temperature detector 24 and the fuel control valve 17 are connected to the control panel 23. And the control panel 23 has a microprocessor 25.
and a control device 26 for the fuel control valve 17. The microprocessor 25 is composed of a fuzzy inference processor 27 and a control rule storage device 28. The fuzzy inference processor 27 performs a logical operation on the manipulated variable KQ to the fuel control valve 17 and outputs the obtained manipulated variable KQ to the control device 26 . The control device 26 corrects the opening degree of the fuel control valve 17 based on the manipulated variable KQ. Specifically, this control device 26 holds opening degree information Q of the valve 23,
The opening degree of the fuel control valve 17 is adjusted according to this opening degree information Q. Each time the operating amount KQn is received, new opening information Qn=Qn-1+KQn is set based on the previously set opening information Qn-1 and the operating amount KQn. That is, in this embodiment, the opening degree of the fuel control valve 17 is changed by the manipulated variable KQ from the fuzzy inference processor 27. The set temperature t0 is also changed by t0,n=t0+kt0,n. Note that t0 here is a standard value.

The control rule storage device 28 also stores control rules (fuzzy rules), conditional parts, and conclusion part membership functions necessary for fuzzy logic operations executed by the fuzzy inference processor 27. Further, 30 is a calculation device, and 31 is a cold water inlet temperature detector provided in the cold water pipe 20 on the inlet side of the evaporator 4. 32 is a high temperature regenerator temperature detector that detects the high temperature regenerator temperature, and 33 is a cooling water inlet temperature detector that detects the cooling water inlet temperature. Arithmetic device 3
0 takes in the temperature data of the chilled water outlet temperature detector 24, chilled water inlet temperature detector 31, high temperature regenerator temperature detector 32, chilled water inlet temperature detector 33, and external environment temperature detector A and calculates the following data. do.

■ Deviation of chilled water outlet temperature (eto) eto = current value - target value ■ Rate of change of deviation of chilled water outlet temperature (dto) dto = current value - previous value ■ Rate of change of cooling water inlet temperature (dtci) dtci = current value - previous value ■ Rate of change in chilled water inlet temperature (dti) dti = current value - previous value ■ Average value of the past 40 samples of eto (e)

0012
]

[Math 1]

■High temperature regenerator temperature change rate (dtg) dtg
=Current value - Previous value ■Outside environmental temperature (tenv) Next, the functional block diagram of the microprocessor 25 is shown in Figure 2.
Shown below. In the figure, 34 indicates data eto, dto, dtci, dti, e, dtg from the arithmetic unit 30.
This is a suitability calculation unit that calculates the suitability of each control rule from the condition part membership function and control rule stored in the control rule storage device 28, and calculates the suitability of each control rule. When the definition is made by a function, the minimum degree of fitness is taken as the degree of fitness. Here, eto, dto, dti, dtci are used as conditional membership functions.
, dtg, and e for NB, NS, ZR, and PS, respectively.
, PB as shown in FIGS. 4 to 9. As you can see, dti, dtci, and e are 0.4, 0.5, and 0.4, 0.5, and 0.0, respectively, in order to reduce the degree of influence.
A weighting of 5 is performed.

[0014] Then, data ten from the arithmetic unit 30
Regarding v, the processing shown in Fig. 3 is performed by a microprocessor. Further, the membership function is defined as shown in FIG.

[0015] The control rules are eto, dto, dt.
Regarding g, it is as shown in FIG. That is, here, rules are not defined for adjacent control rules,
The aim is to shorten the calculation time for fitness. Also, eto,
dto is defined as shown in FIG. Here, NZ and PZ, which will be described later, are added to the conclusion section membership function to improve the degree of convergence of the control amount KQ when eto approaches the set value. Figure 13 for dtci,
dti is defined in FIG. 14, and e is defined in FIG. 15. Furthermore, regarding this e, eto is Z
Only in the vicinity of R, as shown in ■ above, the past 4 of eto
Control performance and convergence are improved by taking the average of 0 samples.

tevn is defined as shown in FIG. Reference numeral 35 denotes a modification section that modifies the conclusion section membership function in the control rule storage device 28 so as to cut off the upper part of the conclusion section membership function in accordance with the degree of fitness obtained by the degree of fitness calculation section 34. Note that the conclusion part membership function is defined as shown in FIG. 14. As can be seen from this figure, NZ and PZ are defined in the vicinity of ZR to improve control.

Reference numeral 36 denotes a disjunction section which superimposes the membership functions modified by the modification section 35 and performs a logical sum; 37 a centroid calculation which computes the center of gravity of the function generated by the disjunction section 36. , and this calculated value is the valve operation amount K
Q to the controller 26.

In such a device, during operation of the absorption chiller, the computing device 30 detects the cold water outlet temperature detector 24, the cold water inlet temperature detector 31, the high temperature regenerator temperature detector 32, and the cooling water inlet temperature detector. For example, a temperature signal is taken in from 33 at a period of 5 seconds. Then, from the temperature signal obtained in this way, the deviation of the chilled water outlet temperature (eto), the rate of change of the deviation of the chilled water outlet temperature (dto), the rate of change of the chilled water inlet temperature (dtci), the rate of change of the chilled water inlet temperature ( dti), etc.
The average value (e) of the past 40 samples of o, the high temperature regenerator temperature change rate (dtg), and the outside environment temperature (tevn) are calculated and sent to the microcomputer 25.

The suitability calculation units 34 and 38 in the microcomputer 25 examine the suitability of the condition parts of all control rules. Then, using this degree of conformity, the correction unit 35
The members of the corresponding conclusion section shown in Figures 17 and 18
Modify the ship function. That is, the portion above the fitness level of each membership function is cut. The logical sum of the membership functions thus modified is the logical sum of the membership functions 36 and 40.
The center of gravity of the member ship function is determined by center of gravity calculating sections 37 and 41. The outputs of the center of gravity calculation units 37, 41 are outputted as the manipulated variable KQn of the fuel control valve 17 and the offset kt0, n of the cold water outlet temperature.

The valve control device 26 generates new opening information Qn based on this manipulated variable KQn and the previous opening information Qn-1.
Calculate =Qn-1+KQn. Then, the fuel control valve 17 is adjusted according to this opening degree information Qn.

Furthermore, the cold water outlet set temperature (t0,n) is calculated as a new set temperature t0,n=t0+kt0,n based on the manipulated variable kt0,n and the previous set temperature standard value t0.

[0022] These operations are repeated at the above-mentioned 5 second period.

[0023]

[Effects of the Invention] As described above, in the present invention, the evaporator,
Absorption chiller control equipment connects an absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the amount of heat generated by the generator based on external conditions. Since the fuzzy rules and membership functions are set to change the set temperature according to the season, the set value of the cold water outlet temperature can be changed automatically depending on the season, instead of being manually set. This can contribute to improved operability.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an absorption refrigerator to which a control device of the present invention is applied.

FIG. 2 is a functional block diagram of a microcomputer used in the device of the present invention.

FIG. 3 is a functional block diagram of a microcomputer used in the device of the present invention.

FIG. 4 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 5 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 6 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 7 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 8 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 9 is a characteristic diagram of a conditional part membership function used in the device of the present invention.

FIG. 10 is a characteristic diagram of a conditional membership function used in the device of the present invention.

FIG. 11 is an explanatory diagram of control rules.

FIG. 12 is an explanatory diagram of control rules.

FIG. 13 is an explanatory diagram of control rules.

FIG. 14 is an explanatory diagram of control rules.

FIG. 15 is an explanatory diagram of control rules.

FIG. 16 is an explanatory diagram of control rules.

FIG. 17 is a characteristic diagram of a conclusion part membership function.

FIG. 18 is a characteristic diagram of a conclusion part membership function.

[Explanation of symbols]

1 High temperature regenerator 2 Low temperature regenerator 3 Condenser 4 Evaporator 5 Absorber 17 Fuel control valve 23 Control section 24 Chilled water outlet temperature detector 25 Microprocessor 26 Control device 27 Fuzzy inference processor A Time information detector

Claims (1)

[Claims] Claim 1: A control device for an absorption refrigerating machine that connects an evaporator, absorber, generator, condenser, etc. to form a refrigeration cycle, and controls the heating amount of the generator according to external conditions, 1. A control device for an absorption refrigerator, characterized in that a fuzzy rule and a membership function are set to change a set temperature using an external environmental temperature of the refrigerator.