JPH10281623A - Method for controlling cooling device by fuzzy reasoning - Google Patents

Abstract

PROBLEM TO BE SOLVED: To smoothly perform a drainage control after defrosting a cooling device by using the temperature setting value of space to be cooled and one input variable and the defrosting time of the cooling device as the other input variable for performing fuzzy reasoning. SOLUTION: A defrosting control part 17 determines a drainage time Tw by the fuzzy reasoning. A setting value TMPset of a temperature in a storage is used as one input variable for the input of the fuzzy reasoning, namely the variable of the former part of a rule. Further, a defrosting time Tdef is used as the other input variable. Then, nine rules are used as reasoning rules, the output variable Tw obtained by the total rules is subjected to fuzzy synthesis by weighted mean, and the drainage time Tw is determined by obtaining the center of gravity, thus determining a proper drainage time while considering the setting value of a temperature in a storage as well as the defrosting time and preventing frost remainder and effectively suppressing the temperature increase in the storage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control method for controlling a cooling device such as a freezer / refrigerator, a freezing / refrigeration case, an air conditioner by fuzzy inference.

[0002]

2. Description of the Related Art Conventionally, in a low-temperature showcase or the like, for example, JP-A-7-151449 (F25D2)
1/08), as shown as an embodiment, a cooler (evaporator) of a cooling device is installed in a duct (cool air circulation path), and the cool air exchanged by the cooler is blown out into the refrigerator to cool. On the other hand, the defroster of the cooling device performs defrosting of the cooler at a predetermined timing.

[0003] The defrosting device comprises an electric heater for heating the cooler, a temperature sensor for detecting the temperature of the cooler, and the like. When the defrosting start time comes, the control device stops the cooling operation and the electric heater turns on. Start heating the cooler. And
When the temperature of the cooler reaches a predetermined defrost recovery temperature based on the output of the temperature sensor, the electric heater is cut off and the cooling operation is restarted.

[0004] In addition, since ice blocks also fall on the dew tray together with water droplets from the cooler, it is necessary to secure a time required for these to be discharged while melting, that is, a draining time after defrosting. For this reason, in the related art, after the energization of the electric heater is cut off, the restart of the cooling operation is prohibited for a preset drainage time such as 5 minutes.

[0005]

However, the state of frost formation on the cooler differs depending on the setting state of the cooling operation and the surrounding environment. That is, since the amount of frost increases in summer or the like, the number of falling ice blocks increases, while in winter or the like, the number of ice blocks decreases. Therefore, if you drain the water for a uniform time,
In summer and the like, time is insufficient, and frost remains, and in winter, it becomes longer on the contrary, causing an unnecessary rise in the internal temperature.

Therefore, in the above publication, the draining time is changed according to the size of the cooler and the temperature change during defrosting. However, the size of the cooler of the low-temperature showcase must be set in the control device one by one. Must be versatile,
Because the state of frost (hardness, amount, or part) and the method of melting also differ depending on the setting value of the internal temperature,
It is not possible to determine the appropriate draining time by judging only the time according to the size of the cooler, and the internal temperature rise due to too long draining time or frost residue due to too short draining time occurs There was also a danger of doing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional technical problem, and provides a control method for smoothly realizing drainage control after defrosting of a cooling device using fuzzy inference. It is.

[0008]

SUMMARY OF THE INVENTION A method of controlling a cooling apparatus according to the present invention comprises the steps of: setting a temperature set value of a space to be cooled as one input variable, and setting a defrost time of the cooling apparatus as another input variable; After obtaining a membership value corresponding to each input variable from a membership function corresponding to each input variable, the output variables of the inference rule are fuzzy synthesized, and an inference result is obtained by taking the center of gravity thereof. Is used to determine the draining time after defrosting, and if the defrosting time is short, the draining time is short, and if the defrosting time is long, the inference rule is set so that the draining time is long. .

According to the present invention, the drainage time after defrosting is determined by performing fuzzy inference using the temperature set value of the space to be cooled as one input variable and the defrosting time of the cooling device as the other input variable. If the taking time is short, the draining time is short, and if the defrosting time is long, the inference rule is set in the direction of increasing the draining time, so that the optimal draining time can be calculated, and the temperature rise and power consumption can be reduced. As a result, the frost residue can be more reliably prevented.

According to a second aspect of the present invention, there is provided a method for controlling a cooling device based on fuzzy inference, wherein the temperature setting value is low, the dewatering time is slightly shortened when the defrosting time is short, and when the defrosting time is long. The inference rule is to lengthen the draining time, shorten the draining time if the defrosting time is short, and set the draining time slightly longer if the defrosting time is long with the temperature set value being high.

According to the second aspect of the present invention, in addition to the above, when the temperature set value is low, the draining time is slightly shortened when the defrosting time is short, and the draining time is lengthened when the defrosting time is long. In addition, in the state where the temperature set value is high, if the defrosting time is short, the draining time is shortened, and if the defrosting time is long, the draining time is slightly longer, so even if the defrosting time is short, In the state where the temperature set value is low, the shortening of the draining time can be limited. On the contrary, even when the defrosting time is long, the extension of the draining time can be limited in the state where the temperature set value is high.

Thus, it is possible to more reliably avoid frost residue in a situation where the temperature setting value is low and frost formation hardens, and unnecessary temperature rise in the cooled space in a situation where the temperature setting value is high. It becomes.

[0013]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows a functional block diagram of a control device 1 of the cooling device. In addition, the cooling device not shown
For example, it cools the inside (cooled space) of a low-temperature showcase (not shown) and controls a refrigerator (not shown) provided with a compressor, a condenser, and the like, and a supply of refrigerant from the refrigerator to a cooler described later. Solenoid valve 2, a decompression device such as an expansion valve that constitutes a known refrigeration cycle together with the refrigerator, the cooler installed in a duct of a low-temperature showcase, and cold air that has exchanged heat with the cooler. It is provided with a cooling fan 4 for circulating in the storage, a defrost heater (electric heater) 6, and the like.

On the other hand, the control device 1 is composed of a general-purpose microcomputer 7, and an input unit 8 of the microcomputer 7 has an internal temperature sensor 9 for detecting the internal temperature of the low-temperature showcase, and a cooler for the cooler. A defrost recovery sensor 11 for detecting the defrost recovery temperature, and a temperature setting switch 12 for setting the temperature in the refrigerator are connected. The output portion 13 of the microcomputer 7 is connected to the solenoid valve 2, the cooling fan 4, and the defrost heater 6.

The CPU of the microcomputer 7 is provided with a defrost control unit 17 for performing fuzzy control using a membership function and nine fuzzy rules as described later.

Next, the operation of the control device 1 will be described. As shown in FIG. 3, the microcomputer 7 sets the internal temperature set by the temperature setting switch 12 (for example, 0
C), an upper limit (for example, + 2 ° C.) is set, and based on the output of the inside temperature sensor 9, if the inside temperature is higher than the upper limit, the solenoid valve 2 is opened and the cooling fan 4 is operated ( ON).

When the solenoid valve 2 is opened, the high-temperature and high-pressure gas refrigerant discharged by the operation of the compressor of the refrigerator is
After being radiated and liquefied by the condenser and decompressed by the expansion valve,
It enters the cooler and evaporates. The cool air cooled by the heat absorption at this time is circulated into the refrigerator by the cooling fan 4, and the refrigerator is cooled.

When the temperature in the refrigerator decreases due to the cooling, and the temperature drops to the set temperature, the microcomputer 7 closes the solenoid valve 2. The cooling fan 4 is operated continuously. As a result, the internal temperature starts to rise again, and when the internal temperature reaches the upper limit, the solenoid valve 2 is opened again.

Next, the defrosting control of the controller 1 will be described. The defrost control unit 17 of the microcomputer 7 periodically closes the solenoid valve 2 by a defrost timer provided as its own function, stops the cooling fan 4 (OFF), and energizes (ON) the defrost heater 6. To start defrosting the cooler (see FIG. 3).

Then, the defrosting of the cooler proceeds and the temperature of the cooler rises, and when the cooler rises to a predetermined defrosting return temperature, a microcomputer based on the output of the defrosting return sensor 11 7 deactivates the defrost heater 6 (OFF) and terminates the defrost.

After the draining is performed after the completion of the defrosting, the operation returns to the cooling operation.
7 is a draining time T by fuzzy inference described below.
Determine w.

In this case, the input of fuzzy inference, ie,
As a variable (fuzzy variable) of the antecedent part of the rule (inference rule), the set value TMPset of the inside temperature is set as one input variable. In this case, the fuzzy labels of the set value TMPset include “NB with a low set temperature of the internal temperature (low set temperature)”, “Zero set value of the internal temperature is intermediate ZO (intermediate set temperature)”, and “ PB with high set value of internal temperature (high set temperature) "is used.

Further, the defrost time Tdef is used as the other input variable. In this case, the fuzzy labels of the defrost time Tdef are “short NB”, “intermediate ZO”, and “long P”.
B "is used.

The output, that is, the output variable Tw of the consequent part of the rule
As a fuzzy label, "NB for shortening the draining time", "NS for slightly shortening the draining time", "ZO for intermediate draining time", and "PS for slightly increasing the draining time" , "PB for extending draining time". Also, nine rules shown in FIG. 4 are used as inference rules.

Next, each rule will be described in detail. The membership function of each rule is shown in FIG. 6, and the first rule is that if the set temperature of the refrigerator is low NB and the defrost time is short NB, the drain time is slightly shortened.
S ”.

That is, in the antecedent part of FIG. 6, the maximum value (1) is obtained when the set value TMPset of the internal temperature is low, and -2.
The mountain-shaped membership function NB gradually decreases from 5 ° C. to −15 ° C., and the set value of the internal temperature becomes −1 at −15 ° C., and gradually increases toward −25 ° C. and −5 ° C. When the set value of the mountain-shaped membership function ZO and the temperature in the refrigerator is high, the maximum value (1) is obtained, and the temperature becomes from -5 ° C to -15 ° C.
Membership function PB that gradually decreases toward
And the membership value is determined by substituting the input variable TMPset for this.

The lower part of the antecedent of FIG. 6 shows a maximum value (1) when the defrost time Tdef is short, and a mountain-shaped membership function NB that gradually decreases from 16 minutes to 28 minutes. It becomes (1) in 28 minutes, and the mountain-shaped membership function ZO gradually decreases toward 16 minutes and 40 minutes, and the maximum value (1) when the defrosting time is long, and from 40 minutes to 1
A mountain-shaped membership function PB that gradually decreases toward six minutes is shown, and a membership value is obtained by substituting the input variable Tdef into this.

The minimum membership value among the membership values is selected as the degree of establishment of the first rule.

The consequent part has a maximum value (1) in the direction of shortening the draining time Tw, a mountain-shaped membership function NB gradually decreasing from 12 minutes to 20 minutes, and a draining time of 20 minutes ( 1), and a mountain-shaped membership function NS that gradually decreases toward 12 minutes and 28 minutes, and a mountain-shape that gradually decreases toward 20 minutes and 36 minutes after draining time becomes (1) at 28 minutes. , The draining time becomes (1) in 36 minutes, and the mountain-shaped membership function PS gradually decreases toward 28 minutes and 44 minutes, and the maximum value in the direction of increasing the draining time Tw ( 1) indicates a mountain-shaped membership function PB that gradually decreases from 44 minutes to 36 minutes, and the area below the satisfaction degree is output as the draining time Tw in the first rule.

The second rule indicates the degree of satisfaction of the condition "if the set temperature of the refrigerator is low NB and the defrosting time is intermediate ZO, the draining time is intermediate ZO". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the degree of establishment of the second rule. The area below is output as the draining time Tw in the second rule.

The third rule indicates the degree of satisfaction of the condition that "if the set value of the internal temperature is a low NB and the defrosting time is a long PB, the draining time is set to a long PB". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value among them is selected as the degree of establishment of the third rule. The area below is output as the draining time Tw in the third rule.

The fourth rule indicates the degree of fulfillment of the condition "if the set value of the internal temperature is intermediate ZO and the defrost time is short NB, the drain time is slightly shortened to NS". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the degree of establishment of the fourth rule. The area below is output as the draining time Tw in the fourth rule.

The fifth rule indicates the degree of satisfaction of the condition "if the set value of the internal temperature is intermediate ZO and the defrosting time is intermediate ZO, the draining time is intermediate ZO". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the fulfillment degree of the fifth rule. The area below is output as the draining time Tw in the fifth rule.

The sixth rule indicates the degree of satisfaction of the condition "if the set value of the internal temperature is intermediate ZO and the defrosting time is PB, the draining time is slightly longer PS". In this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the degree of establishment of the sixth rule. The area below is output as the drainage time Tw in the sixth rule.

The seventh rule indicates the degree of satisfaction of the condition "if the PB is a PB with a high internal temperature setting and the NB has a short defrosting time, the draining time is shortened to an NB". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the satisfaction degree of the seventh rule. The area below is output as the draining time Tw in the seventh rule.

The eighth rule indicates the degree of fulfillment of the condition "if the set temperature of the refrigerator is high PB and the defrosting time is intermediate ZO, the draining time is intermediate ZO". In this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value of each of them is selected as the satisfaction degree of the eighth rule, and the satisfaction degree of the consequent part is determined. The area below is output as the drainage time Tw in the eighth rule.

The ninth rule indicates the degree of fulfillment of the condition "if the PB is a PB with a high internal temperature and the defrosting time is a long PB, the draining time is set to a slightly longer PS". Also in this case, the membership value of the input variable TMPset and the membership value of Tdef are obtained in the same manner as described above, and the minimum membership value among them is selected as the degree of establishment of the ninth rule, and the degree of establishment of the consequent part is determined. The area below is output as the draining time Tw in the ninth rule.

The output variable Tw obtained by all the above rules
Are subjected to fuzzy synthesis using a weighted average, and the center of gravity is determined to determine the drainage time Tw. Note that the set temperature TMPset and the defrost time Tdef in each of the above rules are used.
FIG. 5 is a three-dimensional diagram showing the relationship between the drainage time Tw and the drainage time Tw. As is clear from this figure, the shorter the defrosting time, the shorter the draining time, and the longer the defrosting time, the longer the draining time. Also, the higher the set temperature, the shorter the drainage time, and the lower the set temperature, the longer the drainage time. However, it can be seen that the contribution of the set temperature is set to be smaller than the defrost time.

Next, the above-described operation will be executed assuming an actual situation with reference to the operation flowchart of the microcomputer 7 in FIG. The microcomputer 7 determines in step S1 whether or not the draining flag (F) is set (1). If it is assumed that the draining flag (F) is reset (0) here, the defrosting flag is set in step S2. Is determined.

Assuming that the microcomputer 7 has been reset in step S2, the microcomputer 7 determines whether or not the defrosting start flag has been set in step S3. If so, the microcomputer 7 proceeds to step S4 and proceeds to step S4. The temperature control is performed by the solenoid valve 2 and the cooling fan 4 based on the set temperature.

Next, when the predetermined defrosting time is reached by the defrosting timer, the microcomputer 7 sets a defrosting start flag. From step S3, the microcomputer 7 proceeds to step S5 to set the defrosting flag. As described above, the electromagnetic valve 2 is closed, the cooling fan 4 is stopped, and defrosting for energizing the defrost heater 6 is started.

Then, from the next step S2, the process proceeds to step S7, in which the microcomputer 7 counts the defrosting time by a timer having its own function, and in step S8, the temperature of the cooler detected by the defrosting recovery sensor 11 is reduced. It is determined whether or not the return temperature has been reached. If it has not reached here, the microcomputer 7 repeats step S1, step S2, step S7, and step S8 to continue defrosting the cooler.

When the temperature of the cooler rises to the defrost recovery temperature as described above, the microcomputer 7 proceeds from step S8 to step S9 to set the draining time Tw by fuzzy inference described below.

That is, at this time, TMPset = x (−27
° C) is “the set value of the internal temperature is low”, and Tdef =
If y (15 minutes) is “short defrost time”, only the first to third rules are hit in the membership function on the antecedent in FIG. 6, and the membership function on the antecedent is in the first. ,
Only the fourth and seventh rules hit. Each membership value is (1).

Only the first rule can be obtained as a conclusion of each rule based on these membership values. Even when the rules are superimposed, the entire area of the consequent part of the first rule becomes the drainage time. This center of gravity sets the drainage time Tw to 20
Minutes (slightly shorter), and the draining time Tw is 20
Determined in minutes and set.

TMPset = x (−4 ° C.) indicates “the set value of the internal temperature is high”, and Tdef = y (42
6), the membership function on the antecedent part of FIG. 6 hits only the seventh through ninth rules, and the membership functions under the antecedent part are the third and sixth members. And only the ninth rule. Each membership value is (1).

Only the ninth rule can be obtained as a conclusion of each rule based on these membership values. Even when the rules are superimposed, the entire area of the consequent part of the ninth rule becomes the drainage time. This center of gravity makes the draining time Tw 36
Minutes (slightly longer) and the draining time Tw is 36
Determined in minutes and set.

Next, the microcomputer 7 sets the draining flag in step S10, closes the solenoid valve 2, stops the cooling fan 4, deenergizes the defrost heater 6 in step S11, and starts draining.

Next, the process proceeds from step S1 to step S12 to determine whether or not the draining time Tw set in step S9 has elapsed. If not, the steps S1 to S12 are repeated. When the drainage time Tw set in step S9 has elapsed, the microcomputer 7 proceeds from step S12 to step S12.
The program proceeds to step 13 to clear all the flags, and returns to the cooling operation as described above (steps S1 to S4).

As described above, in the present invention, not only the defrosting time but also the appropriate draining time taking into account the set value of the internal temperature is determined, and the prevention of the remaining frost and the increase in the internal temperature are effectively suppressed. Will be able to In the embodiment, the low-temperature showcase has been described as an example, but the present invention is not limited to this, and the present invention is also effective for an air conditioner that air-conditions a room that is a cooled space.

[0051]

As described above in detail, according to the present invention, the temperature set value of the space to be cooled is used as one input variable, and the defrosting time of the cooling device is fuzzy inferred as the other input variable, thereby draining water after defrosting. In addition to determining the time, if the defrosting time is short, the draining time is shortened, and if the defrosting time is long, the inference rule is set in the direction of increasing the draining time. It is possible to reduce the rise and the power consumption, and it is possible to more reliably prevent the remaining frost.

According to the second aspect of the present invention, in addition to the above, when the temperature set value is low, the draining time is slightly shortened when the defrosting time is short, and the draining time is lengthened when the defrosting time is long. In addition, in the state where the temperature set value is high, if the defrosting time is short, the draining time is shortened, and if the defrosting time is long, the draining time is slightly longer, so even if the defrosting time is short, In the state where the temperature set value is low, the shortening of the draining time can be limited. On the contrary, even when the defrosting time is long, the extension of the draining time can be limited in the state where the temperature set value is high.

Thus, it is possible to more reliably avoid undesired frost in a situation where the temperature setting value is low and frost hardens, and an unnecessary rise in the temperature of the cooled space in a situation where the temperature setting value is high. It becomes.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device of a cooling device embodying the present invention.

FIG. 2 is an operation flowchart of a microcomputer of the control device.

FIG. 3 is a diagram showing a change in the internal temperature including defrosting.

FIG. 4 is a diagram illustrating fuzzy rules (inference rules) in a defrost control unit.

FIG. 5 is a diagram showing the fuzzy rule of FIG. 4 in a three-dimensional manner.

FIG. 6 is a diagram showing a membership function used for inference in FIG. 4;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Control device 2 Solenoid valve 6 Defrost heater 7 Microcomputer 9 In-chamber temperature sensor 11 Defrost recovery sensor 17 Defrost control part

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hisagan Kajita 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Sanyo Electric Co., Ltd.

Claims (2)

[Claims] 1. A temperature setting value of a space to be cooled is set as one input variable, and a defrost time of a cooling device is set as another input variable. Each input variable is obtained from a membership function corresponding to each input variable of a plurality of inference rules. , A fuzzy combination of the output variables of the inference rule, obtaining the inference result by taking the center of gravity, and using this for determining the draining time after defrosting. In the above, when the defrosting time is short, the draining time is short, and when the defrosting time is long, the control of the cooling device by fuzzy inference is characterized in that the inference rule is set in a direction to increase the draining time. Method. 2. In a state where the temperature set value is low, the draining time is slightly shortened when the defrost time is short, and the drain time is lengthened when the defrost time is long, and the temperature set value is high. The cooling device based on the fuzzy inference according to claim 1, wherein the dewatering time is shortened when the defrosting time is short, and the dewatering time is slightly increased when the defrosting time is long. Control method.