JPH0674573A - Method for controlling expansion valve in vapor-compression refrigerating apparatus - Google Patents

Abstract

(57) [Summary] [Purpose] Stable control is performed even if the length of the refrigerant pipe varies depending on the installation location. [Composition] Expansion valve control of a vapor compression refrigeration system for controlling the degree of opening / closing of an expansion valve for increasing / decreasing the flow rate of a refrigerant circulating in a refrigerant pipe in accordance with an operation amount output by a control unit based on a temperature state inside an evaporator In the method, the length of the refrigerant pipe is inferred from the change in the temperature state inside the evaporator, and the optimum control parameter corresponding to the inferred length of the refrigerant pipe is set in the control unit to control the expansion valve. I chose

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling an expansion valve of a vapor compression refrigeration system, which appropriately controls the opening / closing degree of an expansion valve for controlling the flow rate of a refrigerant.

[0002]

2. Description of the Related Art Generally, in a vapor compression refrigerator used for indoor air conditioning, the indoor temperature is constantly controlled so as to reach a set temperature, and at that time, the cooling capacity of the refrigerator itself is utilized to the maximum extent. In addition, in order to keep the refrigerant state inside the refrigerator stable, the refrigerant flow rate is controlled. For example, in the case of cooling, the refrigerator absorbs heat from the room into the refrigerant inside the evaporator,
Heat is discharged indoors and outdoors from the condenser, and when the room temperature is higher than the set temperature, the refrigerator is operated to the maximum, and when the room temperature is lower than the set temperature, the compressor operation is stopped and the indoor and outdoor heat exchange is performed. Have stopped. In this case, unless the internal refrigerant state of the refrigerator is kept stable, indoor and outdoor heat exchange is not performed stably, and by keeping the internal state of the refrigerator stable,
As a result, the indoor temperature is kept stable.

Generally, the opening / closing degree of an expansion valve is controlled as a means for controlling the refrigerant flow rate of a refrigerator.
There are many control means for this purpose even if they are in principle, but one example thereof is the Super Heat control (hereinafter referred to as “SH control”) that performs control based on the detection of the temperature state inside the evaporator. explain.

FIG. 12 shows a conceptual diagram of a refrigerant circuit of a vapor compression refrigerator. In the figure, 1 is an evaporator, 2 is a condenser,
3 is a compressor, 4 is an expansion valve, and this drawing is applied to the case of an indoor air conditioner, 5 is an outdoor unit, and 6 is an indoor unit. A solid line 7 inside the outdoor unit 5 and the indoor unit 6 indicates a refrigerant pipe through which the refrigerant moves, and a dotted line 8 connects the outdoor unit 5 and the indoor unit 6 in the refrigerant pipe 7 in particular. Shows the piping for. Here, the refrigerant flows through the pipe in the direction of the arrow in the figure. In FIG. 12, the compressor 3
Is on the outdoor unit side, but may be on the indoor unit side.

When the refrigerator is used as an indoor air conditioner, a four-way valve is provided at the outlet of the compressor 3,
This is done by switching the direction in which the refrigerant flows. When FIG. 12 operates as a heater, the roles of the evaporator 1 and the condenser 2 are reversed. Since the refrigerant pipes 7 intersect in a zigzag manner inside the evaporator 1 and the condenser 2, the surface area of the pipes exposed to the outside air is increased and the heat exchange rate between air and the refrigerant is improved. Here, as shown in FIG. 12 as an indoor air conditioner, the SH
In the control, the temperature of the refrigerant inside the evaporator, for example, the outlet position a
The temperature of the refrigerant inside the pipe at and the temperature of the refrigerant inside the pipe corresponding to the intermediate position b are measured, and the temperature difference is controlled to be a constant value ec. As a result, the internal state of the entire refrigerant machine is stabilized and a high refrigerating capacity is brought out. Since the SH control can be controlled only by the information of the evaporator itself, it is an effective control means when it is physically difficult or costly to measure the states of the condenser 2, the compressor 3, and the like. .

By the way, the expansion valve 4 for controlling the flow rate of the refrigerant is
Generally, it is an electric type, and its opening / closing degree can be discretely controlled, and by inputting a control pulse, one opening / closing step amount can be changed as a unit operation amount. That is, for example, if the degree of opening / closing in the fully closed state is 0 and the degree of opening / closing in the fully opened state is 500, the degree of opening / closing during that period can be controlled to a value divided into 500 steps. Therefore, generally, the motor-operated valve has a structure similar to that of a stepping motor, and the drive system is almost the same. The refrigerator is used by installing the indoor unit and the outdoor unit in an appropriate place where they can be installed according to the installation environment of the user.

[0007]

However, the above expansion valve control method for a vapor compression refrigeration system has the following problems.

First, since the length of the pipe 8 connecting the indoor unit 6 and the outdoor unit 5 differs depending on the installation location of the refrigerator, there is a problem that the stability of SH control is greatly affected. . That is, in the conventional method, the control parameters according to the standard pipe length are set in advance, and since the control parameters are delivered in this state, if the pipe length at the user's end is different from the standard,
The response characteristics to the amount of change in the opening / closing degree of the expansion valve were also different, and the internal state of the refrigerator could not be controlled stably. In this case, it is possible to actually measure the pipe length, but measuring with a measure or the like cannot be said to be a realistic method, and it may be difficult to measure the pipe length depending on the installation location.

Second, in the conventional method of only finely adjusting the opening / closing degree of the expansion valve, one step (unit operation amount) is large, so that the internal state of the refrigerator can be accurately maintained in a stable state. Has the problem of being difficult. This problem will be described with reference to FIG. 13. Until the time t1, the SH control stabilizes the temperature detection signal d1 and the temperature detection signal d2, and the temperature difference ec is a target value and does not change.
However, after the time t1, when a change factor, for example, load fluctuation or disturbance occurs and the temperature detection signal d1 decreases and becomes smaller than the target temperature difference, the opening / closing degree of the expansion valve is decreased by one step (unit operation amount) stable direction. . As a result, the internal state of the refrigerator also changes and the temperature detection signal d1 and the temperature detection signal d
2 changes, but becomes a steady state at the time t3 with the temperature difference e'c '. In this case, the expansion valve 4 is controlled to return the temperature difference e'c 'to the temperature difference ec at the next control timing, but it takes a long time to return the temperature difference ec to a stable state, and vibration May become.

The reason for such a state is that when the internal state of the refrigerator shifts from a stable state to an unstable state, one step (unit operation amount) is used to suppress the above-mentioned changed state or restore the original state. ) That is, the expansion valve 4 is throttled, but since the minimum change amount of the throttle in one step is large, the change in the refrigerant flow rate is large and an overshoot occurs in the restoring direction, resulting in an unstable state contrary to the purpose. Because it will be transferred to.

Conventionally, due to the above problems, when stability is obtained within a certain range, the expansion valve 4 is kept as stable as possible by keeping the opening / closing degree unchanged. Even if the expansion valve 4 is controlled to suppress the above, the response is slow, and as a result, stable control with high accuracy cannot be obtained. In this case, it is conceivable to reduce one step (unit operation amount) of the expansion valve 4, but there is a problem that the cost will increase significantly.

Therefore, the present invention solves the problem caused by the large unit operation amount of the expansion valve by setting the optimum control parameter corresponding to the length of the refrigerant pipe, and provides stable and accurate control. It is an object of the present invention to provide an expansion valve control method for a vapor compression refrigeration system obtained.

[0013]

According to a first aspect of the present invention, a compressor, a condenser, an expansion valve and an evaporator are circulated and connected by a refrigerant pipe, and a control calculation is performed based on a state of a refrigerant temperature inside a refrigerator. In the expansion valve control method of the vapor compression type refrigerating apparatus for controlling the opening / closing degree of the expansion valve according to the operation amount obtained, the operation amount is determined, and the length of the refrigerant pipe is changed from the change in the state of the refrigerant temperature inside the refrigerator. The expansion valve is controlled by analogizing and setting the optimum control calculation parameter corresponding to the analogized length of the refrigerant pipe.

According to a second aspect of the present invention, the compressor, the condenser, the expansion valve and the evaporator are circulated and connected by a refrigerant pipe, and
An expansion valve for a vapor compression refrigeration system that controls the operation amount based on the state of the refrigerant temperature inside the refrigerator to obtain an operation amount and changes the opening / closing degree of the expansion valve by a unit step amount in accordance with the operation amount thus obtained. In the control method, if the opening / closing degree of the expansion valve is changed by a unit step amount based on the operation amount, the change in the refrigerant temperature from the stable state is large, and conversely, if the refrigerant temperature becomes unstable, the unstable state is suppressed. In order to achieve this, after changing the opening / closing degree of the expansion valve by a unit step, the opening / closing degree of the expansion valve is changed by a unit step in a direction opposite to the direction in which the opening / closing degree of the expansion valve is changed after a lapse of a predetermined time.

[0015]

According to the first aspect of the present invention, the optimum control parameter corresponding to the length of the estimated refrigerant pipe is set, and the internal state of the vapor compression refrigeration system can be controlled stably regardless of the installation location. it can.

According to the second aspect of the present invention, when the manipulated variable is less than the amount for generating the unit 2 step amount, the expansion valve is changed by the unit step amount, and then the opening / closing degree is changed in the reverse direction at an appropriate timing. Change. As a result, when the unit operation amount is output, conversely, stable control can be performed even when there is a slight change in which the internal temperature state becomes unstable.

[0017]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a first embodiment of the present invention. In the figure, 4 is the expansion valve explained in FIG. 12, and 9 is FIG.
2 detects the temperature at point a inside the evaporator 1 and outputs a temperature detection signal d1, and the temperature detector 10 detects the temperature at point b inside the evaporator 1 shown in FIG. Signal d
A temperature detector that outputs 2; 11 is a control unit that calculates a manipulated variable with a control parameter so that the difference between the temperature detection signal d1 and the temperature detection signal d2 is a preset value, and outputs the amount.
Reference numeral 13 is an inference unit for inferring the pipe length, which will be described in detail later. The control unit 11 may obtain the operation amount by fuzzy inference, and the inference unit 13 may be a neural network as a method of analogy rather than fuzzy inference.

In this embodiment, paying attention to the fact that there is a constant causal relationship between the refrigerant pipe length and the internal state of the refrigerator, that is, the internal temperature change of the refrigerator, and the inference unit 13 determines the pipe length. It is inferred that the PID parameter, for example, is set as the control parameter.

Specifically, referring to FIG. 2 showing the time response of the temperature inside the evaporator 1, the temperature detection signal d1 and the temperature detection signal d2 are detected until the time t1 and both of them are detected. The temperature difference is stable because it is controlled by the control unit 11. In this state, if the temperature detection signal d1 starts to decrease at time t1 for some reason, that state is detected, and the control unit 11 operates the expansion valve 4 at time t2 to perform control so as to obtain the original stability. . With this operation, the temperature detection signal d1 and the temperature detection signal d2 after time t2 and the slope are
Depends on the time response characteristics depending on the refrigerant pipe length. That is, if the length of the refrigerant pipe is large, the response when the opening / closing degree of the expansion valve 4 is changed is delayed. Therefore, the rise of the change of the temperature detection signal d1 and the temperature detection signal d2 after operating the expansion valve 4 at time t2. If the refrigerant pipe is small, the rise is quick and the inclination becomes large.

In practice, parameters other than the internal state of the evaporator 1 described above, such as power supply frequency, indoor and outdoor environmental temperature, that is, load, etc., also affect the above-mentioned causal relationship between the two. Now, the analogy of the pipe length is carried out in consideration of these factors.

Next, a case where fuzzy inference is used as a pipe length analogy method of the present invention will be described.

First, the opening / closing degree of the expansion valve, the opening / closing degree change amount, the change amount of the temperature detection signal d1 and the change amount of the temperature detection signal d2 are defined as the antecedent part membership function of the fuzzy inference.
Furthermore, the pipe length is defined as a consequent part membership function.

For example, as shown in FIG. 3, the opening / closing degree change amount as the antecedent part membership function is defined to be correct and moderate in step 2, and large in steps 3 and above. Detection signal d as
As shown in FIG. 4, the change amount of 1 is defined as correct and medium when the temperature is 5 ° C. and correct and large when the temperature is 7.5 ° C. or higher. Further, as shown in FIG. 5, the pipe length as a consequent part membership function is defined as 12.5 m or less being correctly short, 25 m being properly medium, and 37.5 m or more being correctly long.

Next, in practice, it is necessary to describe rules in many cases, but here, for the sake of simplicity, consider the following three rules, for example.

First, the rule (1) is that "if the opening / closing degree change amount is large and the change amount of the temperature detection signal d1 is medium,
The pipe length is long ", the rule (2) is" if the opening / closing degree change amount is large and the change amount of the temperature detection signal d1 is large, the pipe length is medium ", and the rule (3) is" openness degree change amount is medium ". If the amount of change in the temperature detection signal d1 is large, the pipe length is short. "

According to the above definition, for example, the opening / closing degree change amount is I1 (3STE) as an input term to the fuzzy inference.
P), the change amount of the temperature detection signal d1 is J1 (6.25 ° C.)
The reasoning will be described with reference to FIG.

First, in rule 1, the antecedent conformity of the opening / closing degree change amount I1 is 1, and the antecedent conformance of the change amount J1 of the temperature detection signal d1 is 0.5. Then, in these two antecedents, if the smaller one is the fitness of the entire antecedent,
The consequent part conformance is 0.5. Next, in Rule 2, the antecedent part of the opening / closing degree change amount I1 has a compatibility of 1 and a temperature detection signal d1.
Of the change amount J1 is 0.5, and if the smaller of these two antecedents is taken, the congruence of the consequent is 0.5. Finally, in rule 3, the antecedent part conformity of the opening / closing degree change amount I1 is 0, and the antecedent part conformity of the change amount J1 of the temperature detection signal d1 is 0.5. In this case, the two antecedent parts are small. If the one is taken, the consequent part conformance becomes 0.

As a result, the suitability of the consequent part of rule 1 is
A trapezoidal part below 0.5 in the drawing, the consequent part of rule 2 of the rule 2 is a trapezoidal part below 0.5 in the thick line, and a consequent part of rule 3 is 0 in the illustrated thick line. . As a result, when the MIN-MAX method is applied to the rules 1 to 3, a composite figure of the pipe length shown at the right end of FIG. 6 is obtained, and the center of gravity H1 is obtained by obtaining the center of gravity from this composite figure. This center of gravity H1 is estimated to be the pipe length.

Similarly, the opening / closing degree change amount is I as an input.
2. When the change amount J1 of the temperature detection signal d1 is shown in FIG. 7, the consequent part conformance is 0 in rule 1, 0 in rule 2, and 0.5 in rule 3, and when the center of gravity is obtained from the composite figure, ,
A pipe length H2 is obtained.

The membership function and the inference rule are experimentally obtained in advance, and are defined from the correspondence relation of each variable. Further, since the estimated pipe length and the appropriate control parameter corresponding thereto have a one-to-one correspondence, it is possible to define the control parameter instead of the pipe length as a consequent part. For example, when the control unit 11 is PID control, the parameters of the proportional term and the integral term are inferred and changed by the inference unit 13, and when the control unit 11 is fuzzy control, the shape of the membership function is changed or fuzzy inference is performed. The output result of the opening / closing degree manipulated variable by is directly weighted.

Next, a case where a neural network is used as a pipe length analogy method of the present invention will be described with reference to the model of FIG.

The input layer of the neural network (hereinafter referred to as "NN") is a combination of five variables of the expansion valve opening / closing degree, the room temperature, the change amount of the temperature detection signal d1 and the temperature detection signal d2 as shown in the figure, and the output layer. Is the pipe length or a plurality of control parameters a, b, c.

First, data of causal relationships between some input variables in the input layer and output values in the output layer obtained by experiments are input to the NN, and this is used as a teacher to repeatedly calculate the NN. Train students to change calculation parameters for calculations in. After learning, the NN outputs appropriate pipe lengths or control parameters corresponding to combinations of individual inputs that are not taught during learning, and the control parameters of the control unit 11 are changed.

The case of FIG. 8 will be specifically described.
First, from an operation experiment in a refrigerator, a change amount (that is, a slope) of the temperature detection signal d1 and the temperature detection signal d2 at a certain pipe length, a certain room temperature, a certain expansion valve opening / closing degree, and a certain expansion valve opening / closing change amount is determined. taking measurement. Then, some of these parameters are changed and measured again. This measurement is performed for typical values of each parameter. For example, the pipe length is 5 m, 10 m, 15 m, etc., and the room temperature is 2
Temperature detection signal d1 for 0 ° C, 25 ° C, 30 ° C, etc.
And the amount of change in the temperature detection signal d2 is measured. The NN is made to learn by using the input / output data thus obtained as a teacher. However, in the NN after learning, the amount of change in the temperature detection signal d1 and the temperature detection signal d2 is not obtained from the pipe length, but the pipe length is obtained from the amount of change in the temperature detection signal d1 and the temperature detection signal d2. In this case, the NN simply learns what the combination of the input / output variables is, so that such a thing is possible. Next, after learning, the value when the NN is not allowed to learn, for example, the room temperature is 2
Even if 2 ° C or the like is input, an appropriate pipe length is estimated and output from all combinations of inputs in that case. By making the NN learn in this way, the required pipe length can be estimated by conducting some representative experiments without experimenting with all combinations of input and output. In addition, in FIG. 8, since the case of cooling is described, the room temperature is set, but in the case of heating,
It becomes the outdoor temperature.

The power supply frequency may be an input variable of NN, but in the case of 60 Hz, it is 50
In the case of Hz, it is handled by multiplying the output value by a coefficient obtained in advance by an experiment.

Although the pipe length has been described in the learning of the NN, the object of the present invention is to obtain a control effect that does not depend on the pipe length by changing the control parameter according to the estimation of the pipe length. If the pipe length is known, the control parameter at that time is uniquely determined. Therefore, similar to the case of using fuzzy inference, the same result can be obtained by using the control parameter instead of using the pipe length for learning NN. In this case, there is no need to convert the pipe length into control parameters. In the case of fuzzy control, the control parameters include a coefficient for weighting the expansion valve operation amount as a result of fuzzy inference.
In the case of PID control, the terms P, I, and D correspond.

The above-mentioned analogy of the pipe length may be established by providing means for analogy only during a trial run at the time of installation and inputting and saving the analogy result, which is not always necessary during operation. In this way, since the control parameter of the control unit 11 is changed according to the pipe length at the time of installing the refrigerator, the internal state of the evaporator 1 is stabilized and the control state can be stabilized.

In this embodiment, the case of SH control has been described, but the pipe length analogy method can be applied to other control means, and analogy methods other than neural networks or fuzzy inference methods may be used.

Next, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 9 is a block diagram showing the second embodiment of the present invention. In the figure, the control unit 14 includes a control timing generation unit 15, a control command unit 16, a drive pulse generation unit 17, and a reverse rotation timing generation unit 18.
Is connected to a temperature detector 9 and a temperature detector 10, and the drive pulse generator 17 is connected to the expansion valve 4.

In the present embodiment, when the factor of change from the stable state of the refrigerant temperature inside the refrigerator is a slight load change or disturbance, the expansion valve 4 is driven one step in the original stable direction according to the manipulated variable. After a predetermined time within the control cycle, the temperature is overturned by one step in the opposite direction to the stable direction to suppress temperature overshoot due to a change in the internal state, and the internal state is quickly kept stable.

Here, the control timing generation section 15 outputs a control timing signal of a constant cycle to the control command section 16. When the control command unit 16 receives the control timing signal, it takes in the temperature detection signal d1 and the temperature detection signal d2 from the temperature detector 9 and the temperature detector 10, and determines the manipulated variable as PID.
Calculate with control parameters such as.

The drive pulse generator 17 outputs a pulse signal to the expansion valve 4 according to the operation amount from the control commander 16.
The reverse rotation timing generation unit 18 outputs one step (unit operation amount) in the stable direction when the reverse rotation drive command is issued from the control command unit 16, inputs a measurement command for S1 time, and generates a drive pulse after S1 time has elapsed. A command for one-step (unit operation amount) reverse rotation drive is output to the unit 17 in the direction opposite to the stable direction.

Next, the operation of the control unit 14 of this embodiment will be described with reference to FIG.
This will be described with reference to 0.

First, the control command section 16 receives a control timing signal from the control timing generation section 15 (10
1), the temperature detection signal d1 and the temperature detection signal d2 are read from the temperature detector 9 and the temperature detector 10 (102). The control command unit 16 calculates the manipulated variable by the control parameter based on the temperature difference between the temperature detection signal d1 and the temperature detection signal d2 with respect to a predetermined target value (103).

Subsequently, the control command section 16 does not output the drive pulse to the drive pulse generation section 17 by setting the actual step to 0 when the operation amount calculated above is, for example, less than 0.5 step ( 104) If the number of steps is 0.5 or more, it is determined whether or not reverse drive is performed (105). In this determination, when it is not the reverse drive, for example, when the calculated operation amount is 1.5 steps or more, one step or more is output to the drive pulse generation unit 17 (106).

In the case of reverse rotation drive in the above determination, for example, when the calculated operation amount is 0.5 step or more and less than 1.5 step, the control command section 16 causes the drive pulse to stabilize Step 1. The generation unit 17 is instructed to output, while the reverse rotation timing generation unit 18 is output a measurement command for a fixed time S1 (107). The reverse rotation timing generation unit 18 outputs a command for reverse rotation drive of the expansion valve 4 to the drive pulse generation unit 17 after the lapse of S1 time (109). Subsequently, the control command unit 16 again reads the temperature detection signal d1 and the temperature detection signal d2 from the temperature detector 9 and the temperature detector 10, and calculates the manipulated variable (111). As a result, when the manipulated variable is changed, a drive command for one step is output to the drive pulse generator 17 (112) (1
13).

The operation of the above-described reverse drive will be described with reference to FIG. 11. Until the time t1, the temperature difference ec between the temperature detection signal d1 and the temperature detection signal d2 is substantially equal to the target value and stable. In this state, when the temperature detection signal d1 slightly decreases after time t1 due to disturbance or the like, the expansion valve 4 is operated in the one-step closing direction and the restoring direction at time t2. Then S
At time t3 one hour later, the expansion valve 4 is operated by one step in the opening direction, that is, in the direction opposite to the one before. As a result, FIG.
As can be seen from comparison with No. 3, the internal state does not shift to the unstable direction, but the temperature difference ec is maintained at time t4, and the internal state stabilizes in a slightly increased state. The fixed time S1 measured by the reverse rotation timing generator 18 is set by previously determining an optimum time by an experiment. Further, since the expansion valve is operated in the reverse direction, the opening / closing degree does not change at times t1 and t4. However, if the change in state after time t1 is large, the opening / closing degree may have to be changed by one step, so that the temperature detection signal d1 and the temperature detection signal d2 are read again after the reverse rotation pulse is output, and the operation amount A calculation is performed to determine whether to output one step. Thus, stable control of the output of the reverse rotation pulse can be obtained when the change at time t1 is small, but in the case of a large change, the response by the expansion valve operation is delayed. Therefore, the operation amount calculation result at time t1 is, for example, 1.
When the number of steps is 5 or more, no reverse rotation drive can be performed, which enables swift response to a large change.

As described above, in the present embodiment, when the change factor from the stable state is a slight disturbance, the one-step operation amount is changed in the stable direction, and the one-step operation amount is changed in the opposite direction after a predetermined time. It is possible to prevent overshoot due to a large amount and a slow response to a change in the operation amount, and to perform accurate and stable control.

In this embodiment, the example in which the operation amount is calculated by the PID control parameter has been described, but the present invention is not limited to this, and a method of inferring the operation amount by fuzzy inference may be used. In this fuzzy inference, the temperature detection signal d1
And the difference between the temperature difference of the temperature detection signal d2 and the target value ec and the amount of change in the difference are input to the fuzzy inference to deduce the operation amount of the expansion valve 4. For example, when there is almost no temperature difference between the target value and the temperature detection signal d1 and the temperature detection signal d2, the manipulated variable is 0.
When the difference between the target value and the temperature difference ec is small, reverse driving is performed. If the target value and the temperature difference ec are large, the operation amount is one step or more depending on the size.

[0052]

As described above, according to the invention of claim 1, the optimum control parameter corresponding to the estimated length of the refrigerant pipe is set. Therefore, the vapor compression type is set regardless of the installation place. The internal state of the refrigeration system can be controlled stably.

According to the second aspect of the present invention, when the unit operation amount is output, conversely, control is performed corresponding to a slight change in the internal state that is unstable, and a stable internal state is obtained.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of an expansion valve control method for a vapor compression refrigeration system showing a first embodiment of the present invention.

FIG. 2 is a response diagram of an evaporator internal temperature of a vapor compression refrigeration system.

FIG. 3 is a diagram showing an example of a membership function of an antecedent part of an opening / closing degree change amount in a method of analogizing a pipe length by fuzzy inference.

FIG. 4 is a diagram showing an example of an antecedent part membership function of a variation amount of a temperature detection signal d1 in a method of analogizing a pipe length by fuzzy inference.

FIG. 5 is a diagram showing an example of a consequent part membership function of a pipe length in a method of inferring the pipe length by fuzzy inference.

FIG. 6 is an explanatory diagram showing a first example of inferring a pipe length by a fuzzy inference method.

FIG. 7 is an explanatory diagram showing a second example of inferring a pipe length by a fuzzy inference method.

FIG. 8 is an explanatory diagram showing an example of analogizing a pipe length by a neural network method.

FIG. 9 is an explanatory diagram of an expansion valve control method for a vapor compression refrigeration system showing a second embodiment of the present invention.

10 is a flowchart showing the procedure of the control method of FIG.

FIG. 11 is an explanatory view showing the operation of FIG.

FIG. 12 is a conceptual diagram of a refrigerant circuit of a vapor compression refrigeration system.

FIG. 13 is a response diagram of the internal refrigerant temperature of the conventional vapor compression refrigerator.

[Explanation of symbols]

 1 Evaporator 2 Condenser 3 Compressor 4 Expansion valve 7 Refrigerant piping 8 Piping 9 Temperature detector 10 Temperature detector 11 Control part 12 Drive pulse generation part 13 Inference part 14 Control part 15 Control timing generation part 16 Control command part 17 Drive pulse Generator 18 Reverse rotation timing generator

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[Procedure amendment]

[Submission date] November 30, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 2

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

2. Description of the Related Art Generally, in a vapor compression refrigerator used for indoor air conditioning, the indoor temperature is constantly controlled so as to reach a set temperature, and at that time, the cooling capacity of the refrigerator itself is utilized to the maximum extent. In addition, in order to keep the refrigerant state inside the refrigerator stable, the refrigerant flow rate is controlled. For example, in the case of cooling, the refrigerator absorbs heat from the room into the refrigerant inside the evaporator,
Condenser being discharged to the outdoor from drive to maximize the refrigerator when the room temperature is higher than the set temperature, the heat exchange chamber out to stop the operation of the compressor when the indoor temperature is lower than the set temperature It has stopped. In this case, unless the internal refrigerant state of the refrigerator is kept stable, indoor and outdoor heat exchange is not performed stably, and by keeping the internal state of the refrigerator stable, the indoor temperature is consequently kept stable.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

FIG. 12 shows a conceptual diagram of a refrigerant circuit of a vapor compression refrigerator. In the figure, 1 is an evaporator, 2 is a condenser,
3 is a compressor, 4 is an expansion valve, and this figure is suitable for an indoor air conditioner, 5 is an outdoor unit, and 6 is an indoor unit. A solid line 7 inside the outdoor unit 5 and the indoor unit 6 indicates a refrigerant pipe through which the refrigerant moves, and a dotted line 8 connects the outdoor unit 5 and the indoor unit 6 in the refrigerant pipe 7 in particular. Shows the piping for. Here, the refrigerant flows through the pipe in the direction of the arrow in the figure. Although the compressor 3 is on the outdoor unit side in FIG. 12, it may be on the indoor unit side.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0005

[Correction method] Change

[Correction content]

When the refrigerator is used as an indoor air conditioner, a four-way valve is provided at the outlet of the compressor 3,
This is done by switching the direction in which the refrigerant flows. When FIG. 12 operates as a heater, the roles of the evaporator 1 and the condenser 2 are reversed. Since the refrigerant pipes 7 intersect in a zigzag manner inside the evaporator 1 and the condenser 2, the surface area of the pipes exposed to the outside air is increased and the heat exchange rate between air and the refrigerant is improved. Here, as shown in FIG. 12 as an indoor air conditioner, the SH
In the control, the temperature of the refrigerant inside the evaporator, for example, the outlet position a
The temperature of the refrigerant inside the pipe located at the point b and the temperature of the refrigerant inside the pipe located at the intermediate position b are measured, and the temperature difference is controlled to be a constant value ec. As a result, the internal state of the entire refrigerator is stabilized and high refrigerating capacity is brought out. In SH control,
Since it can be controlled only by the information of the evaporator itself, the condenser 2
This is an effective control means when it is physically difficult or costly to measure the state of the compressor or the compressor 3.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

[Correction content]

Conventionally, due to the above problems, when stability is obtained within a certain range, the expansion valve 4 is kept as stable as possible by keeping the opening / closing degree unchanged. To control the expansion valve 4 to suppress
Since it is difficult to respond to changes , accurate and stable control cannot be obtained as a result. In this case, it is conceivable to reduce one step (unit operation amount) of the expansion valve 4, but there is a problem that the cost will increase significantly.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

According to a second aspect of the present invention, the compressor, the condenser, the expansion valve and the evaporator are circulated and connected by a refrigerant pipe, and
In the expansion valve control method of the vapor compression refrigeration system for controlling the opening / closing degree of the expansion valve according to the calculated operation amount, the operation amount is calculated by control calculation based on the state of the refrigerant temperature inside the refrigerator. If the opening / closing degree of the expansion valve is changed by a unit step amount based on this, when the refrigerant temperature changes greatly from the stable state and conversely the refrigerant temperature becomes unstable, the opening / closing of the expansion valve is controlled to suppress the unstable state. The degree of opening and closing of the expansion valve is changed by a unit step in a direction opposite to the direction in which the degree of opening and closing of the expansion valve is changed after a predetermined time has elapsed after the degree of opening and closing is changed by a unit step.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

The case of FIG. 8 will be specifically described.
First, from an operation experiment in a refrigerator, a change amount (that is, a slope) of the temperature detection signal d1 and the temperature detection signal d2 at a certain pipe length, a certain room temperature, a certain expansion valve opening / closing degree, and a certain expansion valve opening / closing change amount is determined. taking measurement. Then, some of these parameters are changed and measured again. This measurement is performed for typical values of each parameter. For example, the pipe length is 5 m, 10 m, 15 m, etc., and the room temperature is 2
Temperature detection signal d1 for 0 ° C, 25 ° C, 30 ° C, etc.
And the amount of change in the temperature detection signal d2 is measured. The NN is made to learn by using the input / output data thus obtained as a teacher. However, in the NN after learning, the amount of change in the temperature detection signal d1 and the temperature detection signal d2 is not obtained from the pipe length, but the pipe length is obtained from the amount of change in the temperature detection signal d1 and the temperature detection signal d2. In this case, the NN simply learns what the combination of the input / output variables is, so that such a thing is possible. Next, after learning, the value when the NN is not allowed to learn, for example, the room temperature is 2
Even if 2 ° C or the like is input, an appropriate pipe length is estimated and output from all combinations of inputs in that case. By making the NN learn in this way, the required pipe length can be estimated by conducting some representative experiments without experimenting with all combinations of input and output. In addition, in FIG. 8, the case of cooling is described.
Since it is indoor temperature, it is outdoor temperature in case of heating.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] Explanation of code

[Correction method] Change

[Correction content]

[Explanation of Codes] 1 Evaporator 2 Condenser 3 Compressor 4 Expansion valve 7 Refrigerant pipe 8 Pipe 9 Temperature detector 10 Temperature detector 11 Control unit 13 Thrusting unit 14 Control unit 15 Control timing generation unit 16 Control command unit 17 Drive Pulse generator 18 Reverse rotation timing generator

Claims (2)

[Claims] 1. A compressor, a condenser, an expansion valve, and an evaporator are circulatively connected by a refrigerant pipe, and a control operation is calculated based on a refrigerant temperature state inside a refrigerator to obtain an operation amount, and the operation amount is determined according to the operation amount thus obtained. In the expansion valve control method of the vapor compression refrigerating apparatus for controlling the opening / closing degree of the expansion valve, the length of the refrigerant pipe is inferred from the change in the state of the refrigerant temperature inside the refrigerator, and the length of the inferred refrigerant pipe is inferred. An expansion valve control method for a vapor compression refrigeration system, characterized in that the expansion valve is controlled by setting an optimum control calculation parameter corresponding to the height. 2. A compressor, a condenser, an expansion valve, and an evaporator are circulated and connected by a refrigerant pipe, and a control calculation is performed based on the state of the refrigerant temperature inside the refrigerator to obtain an operation amount, and the operation amount is determined according to the operation amount thus obtained. In the expansion valve control method for a vapor compression refrigeration system, which controls the opening / closing degree of the expansion valve by changing the opening / closing degree of the expansion valve by a unit step amount, the refrigerant temperature is changed by changing the opening / closing degree of the expansion valve by a unit step amount based on the operation amount. The change from the stable state is large, and conversely, when the refrigerant temperature becomes unstable, after changing the opening / closing degree of the expansion valve by a unit step amount to suppress the unstable state, after a predetermined time elapses. An expansion valve control method for a vapor compression refrigeration system, wherein the opening / closing degree of the expansion valve is changed by a unit step amount in a direction opposite to the direction in which the opening / closing degree of the expansion valve is changed.