JP2889791B2 - Vapor compression refrigerator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor compression refrigerator using an electronic expansion valve whose degree of opening and closing can be arbitrarily adjusted by an electric signal, and more particularly to an electronic expansion valve based on a refrigerant temperature at a refrigerant discharge side of the compressor. The present invention relates to a device for appropriately controlling the opening / closing degree of a vehicle.

[0002]

2. Description of the Related Art Conventionally, in a vapor compression refrigerator used for indoor air conditioning, a room temperature is controlled to be constant so as to reach a set temperature, and at that time, the cooling capacity owned by the refrigerator itself is fully utilized. In order to stably maintain the state of the refrigerant inside the refrigerator, the flow rate of the refrigerant is controlled. For example, in the case of cooling, the refrigerator absorbs heat from the room into the refrigerant inside the evaporator and is released from the condenser to the outside.When the room temperature is higher than the set temperature, the refrigerator operates to the fullest. When the indoor temperature becomes lower than the set temperature, the operation of the compressor is stopped to stop the indoor and outdoor heat exchange.

[0003] As a means for controlling the flow rate of refrigerant in a refrigerator, the degree of opening and closing of an expansion valve is controlled.
There are various control methods for this purpose, one of which is a four-way valve outlet temperature control that performs control based on detection of the discharge temperature of the refrigerant of the compressor. This conventional control method will be specifically described below.

FIG. 9 is a conceptual diagram of a refrigerant circuit of a vapor compression refrigerator. 1 is an indoor heat exchanger, 2 is an outdoor heat exchanger, 3
Is a compressor, and 4 is an electronic expansion valve. The electronic expansion valve 4 is electrically operated by, for example, a stepping motor, and its opening / closing degree can be adjusted. 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 particularly connects the outdoor unit 5 and the indoor unit 6 in the refrigerant pipe. Shows piping. Reference numeral 9 denotes a four-way valve for switching the connection of the compressor 3 connected to the indoor heat exchanger 1 and the outdoor heat exchanger 2 via the refrigerant pipe 7 according to the operation state. Therefore, during indoor cooling operation by switching the four-way valve 9, the refrigerant is connected so that the refrigerant flows from the indoor heat exchanger 1 to the compressor 3, the four-way valve 9, and the outdoor heat exchanger 2 in this order. The two to four-way valve 9, the compressor 3, and the indoor heat exchanger 1 are connected so that the refrigerant flows in this order. Here, this figure shows the case of the indoor cooling operation, and the refrigerant flows in the pipe in the direction of the arrow shown in the figure. Then, in the case of the indoor cooling operation, the indoor heat exchanger 1 operates as an evaporator, and the outdoor heat exchanger 2 operates as a condenser. Reference numeral 10 denotes a temperature detection unit including a thermistor provided on the refrigerant discharge side of the compressor 3, and detects a refrigerant temperature on the refrigerant discharge side of the compressor 3. Therefore, by detecting the refrigerant temperature at the refrigerant discharge side of the compressor 3 by the temperature detecting section 10, the refrigerant temperature discharged from the four-way valve 9, that is, the four-way valve outlet temperature is detected.

[0005] In the four-way valve outlet temperature control, the degree of opening and closing of the electronic expansion valve 4 is controlled such that the refrigerant temperature detected by the temperature detecting unit 10 becomes a preset target value. still,
The target value is set to a value based on the refrigerant temperature at the outlet of the four-way valve during normal stable operation. This stabilizes the internal state of the entire refrigerator and draws out a high refrigerating capacity.

[0006] In the above-mentioned vapor compression refrigerator,
Structure of indoor heat exchanger 1 and outdoor heat exchanger 2, indoor unit 6
Many types of products differing in the shape of the air blowing section, the output horsepower of the compressor 3, and the like.

[0007]

However, in a vapor compression type refrigerator having a large number of models having different specifications, since there are differences in internal characteristics of the refrigerator due to the difference in specifications, only a single control parameter is set. Then, it was difficult to control all the models with high accuracy. In particular,
There was a problem that there were models that could not obtain a high refrigeration capacity.

The reason for such a state is that generally the higher the outlet temperature of the four-way valve, that is, the higher the refrigerant temperature on the refrigerant discharge side of the compressor, the higher the refrigeration capacity and the higher the energy saving effect. This is because when the outlet temperature becomes high, the refrigerant becomes high temperature and high pressure on the refrigerant discharge side of the compressor, and the compressor stop circuit provided for protecting the compressor operates. Therefore, in order to prevent this, a low target temperature is set in consideration of fluctuations in refrigerant dynamic characteristics due to differences in models, environmental conditions, pipe lengths, and the like. That is, as shown in FIG. 10, at the start of the operation of the refrigerator, the refrigerant discharge temperature temporarily rises above the target temperature, that is, is maintained at the target temperature after the so-called overshoot occurs. Since the amount differs depending on the refrigerant dynamic characteristics, the target temperature is determined in consideration of the expected maximum overshoot amount so as not to reach a dangerous temperature that may cause the compressor to stop.

Therefore, conventionally, the same target temperature is set irrespective of the individual refrigerant dynamic characteristics. Therefore, the target temperature at the outlet of the four-way valve, that is, the refrigerant temperature at the refrigerant discharge side of the compressor is set low. There are models that cannot obtain high refrigeration capacity.

The present invention has been made in view of the above-mentioned circumstances, and the target temperature on the refrigerant discharge side of the compressor, which is a reference for controlling the degree of opening and closing of the electronic expansion valve, is different depending on the type of the refrigerant. Provided is a vapor compression refrigerator that corrects the target temperature value based on a detected refrigerant temperature on a refrigerant discharge side and a change amount of the detected refrigerant temperature so as to be sequentially set to a value most appropriate for dynamic characteristics. The purpose is to do.

[0011]

According to a first aspect of the present invention, there is provided a temperature detecting means for detecting a refrigerant temperature at a refrigerant discharge side of a compressor at regular intervals, a detected refrigerant temperature of the temperature detecting means, and the detected refrigerant. Correction temperature calculating means for calculating a change amount of the target temperature of the refrigerant temperature based on the change amount of the temperature, correcting and outputting the target temperature according to the change amount, and a preset target temperature of the refrigerant temperature. A target temperature storage unit that stores the corrected temperature calculated by the corrected temperature calculation unit as a new target temperature, and a difference between the corrected temperature calculated by the corrected temperature calculation unit and the detected refrigerant temperature. Means for controlling the degree of opening and closing of the electronic expansion valve accordingly.

According to a second aspect of the present invention, there is provided a temperature detecting means for detecting a refrigerant temperature at a refrigerant discharge side of a compressor at regular intervals, a refrigerant temperature detected by the temperature detecting means, and a change amount of the detected refrigerant temperature. A correction temperature calculating means for calculating a change amount of the target temperature of the refrigerant temperature, correcting and outputting the target temperature according to the change amount, and storing a preset target temperature of the refrigerant temperature, Target temperature storing means for storing the corrected temperature calculated by the temperature calculating means as a new target temperature; a difference between the corrected temperature calculated by the corrected temperature calculating means and the detected refrigerant temperature; and a change amount of the difference Calculating a valve operation amount of the electronic expansion valve based on the calculation result; and opening and closing the electronic expansion valve according to the valve operation amount calculated by the valve operation amount calculation unit. Control the degree It means a vapor compression type refrigerator including a.

[0013]

According to the present invention, the target temperature on the refrigerant discharge side of the compressor, which is a reference of the degree of opening / closing control of the electronic expansion valve, is detected at a predetermined time interval. The target temperature is corrected based on the amount of change in temperature, and is set to a high target temperature in consideration of refrigerant dynamic characteristics. In addition, at the start of the operation of the refrigerator, the target temperature is set in consideration of the amount of overshoot generated, and at the time of steady operation, it can be set to a higher target temperature.

Further, in the second invention, not only the target temperature value is corrected based on the detected refrigerant temperature on the refrigerant discharge side of the compressor and the amount of change in the detected refrigerant temperature, but also the correction temperature calculation means calculates the target temperature value. The difference between the corrected temperature and the detected refrigerant temperature on the refrigerant discharge side of the compressor, and the valve operation amount of the electronic expansion valve is calculated based on the amount of change in the difference. Opening / closing degree control can be performed.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a refrigerant flow control device of the present invention will be described.
An embodiment will be described with reference to the drawings. The conceptual diagram of the refrigerant circuit of the vapor compression refrigerator has the same configuration as that of the above-described conventional example (FIG. 9).

FIG. 1 is a schematic block diagram of a vapor compression refrigerator showing one embodiment of the present invention. In the figure, 11
Is a control unit to which the refrigerant temperature detected by the temperature detection unit 10 provided on the refrigerant discharge side of the compressor 3 is supplied, and 12 is the target temperature of the refrigerant on the refrigerant discharge side of the compressor 3, that is, the four-way valve outlet. A target temperature storage unit for storing a target temperature, which is constituted by a RAM. In this embodiment, the target temperature = 75 ° C. is stored in the target temperature storage unit 12 as an initial setting. Further, the control unit 11 takes in the four-way valve outlet temperature detected from the temperature detection unit 10 at intervals of 5 seconds.

Reference numeral 13 denotes a temperature detecting unit according to a command from the control unit 11.
Based on 10 detected temperatures and the amount of change in the detected temperature,
A correction temperature calculation unit that calculates a new target temperature (hereinafter, abbreviated as a correction temperature) obtained by correcting the target temperature stored in the target temperature storage unit 12. The correction temperature calculation unit 14 detects the temperature of the temperature detection unit 10 according to a command from the control unit 11. A valve operation amount calculation unit that calculates a valve operation amount of the electronic expansion valve 4 based on the temperature and the correction temperature calculated by the correction temperature calculation unit 13. The electronic expansion valve 4 is electrically operated by a stepping motor and its opening / closing degree can be adjusted. By inputting a control pulse from the control unit 11, the opening / closing degree is changed as a unit operation amount for each step. be able to. In the present embodiment, the opening and closing degree in the fully closed state is set to 0, the opening and closing degree in the fully opened state is set to 500, and the opening and closing degree therebetween is controlled by a value obtained by dividing 500 steps. Is set. Here, the correction temperature calculation unit 13 and the valve operation amount calculation unit 14 obtain the correction temperature and the valve operation amount by fuzzy inference as described later.

Reference numeral 15 denotes a ROM connected to the control unit 11,
The control unit 11 controls the correction temperature calculation unit 13, the valve operation amount calculation unit 14, the electronic expansion valve 4, and the like based on a program stored in the ROM 15.

Next, the correction temperature calculation by the fuzzy inference in the correction temperature calculation section 13 will be described.

First, a refrigerant temperature pt at the four-way valve outlet detected by the temperature detecting unit 10 and a change amount dpt of the refrigerant temperature detected by the temperature detecting unit 10 are defined as a prerequisite part of the fuzzy inference. The target temperature change amount dt is defined.
Note that dpt = 0 is set as an initial value of the change amount dpt.

Specifically, as a membership function of the antecedent part representing the degree of conformity μ ₁ to the four-way valve outlet temperature pt, FIG.
As shown in the figure, a function S applied when the four-way valve outlet temperature is 90 ° C or lower, a function M applied when the four-way valve outlet temperature is 85 ° C to 95 ° C, and a case where the four-way valve outlet temperature is 90 ° C to 100 ° C And a function LL to be applied when the four-way valve outlet temperature is 100 ° C. or higher are defined and stored in the ROM 15.

Further, as a membership function of the antecedent part representing the degree of conformity μ ₂ to the change amount dpt of the four-way valve outlet temperature,
As shown in FIG. 3, a function N applied when the amount of change is negative, a function Z applied when the amount of change is −1 ° C. to 1 ° C.,
Function S applied when the variation is 0 ° C to 2 ° C,
A function M to be applied when the temperature is 1 ° C. to 3 ° C. and a function L to be applied when the variation is 2 ° C. or more are defined and stored in the ROM 15.

[0023] Then, the target temperature change amount dt of the four-way valve outlet is consequent on the basis of the control rule shown in FIG 4 stored in the ROM 15, the fitness of the antecedent membership functions mu ₁ , it is calculated from μ _2.

Therefore, according to the above definition, for example, when the four-way valve outlet temperature is 87.5 ° C. and the change amount is −0.5 ° C., the antecedent degree μ ₁ for the four-way valve outlet temperature is S: 0.
5, M: 0.5, L: 0, LL: 0, and the antecedent part fitting degree μ ₂ for the four-way valve outlet temperature change amount is N: 0.5, Z: 0.5, S: 0,
M: 0 and L: 0. As a result, the following four rules are established. And about the following four rules,
The MIN-MAX method is applied, and the smaller of the conformity μ ₁ and μ ₂ of the antecedent part is defined as the conformity of the entire antecedent part, that is, the conformity μ _{3 of the} consequent part.

Pt = S (μ ₁ = 0.5), dpt = N (μ ₂ =
0.5), dt = 0 (μ ₃ = 0.5) pt = S (μ ₁ = 0.5), dpt = Z (μ ₂ = 0.5), dt = 1 (μ ₃ = 0.5) pt = M (μ ₁ = 0.5), dpt = when N of _{(μ 2 = 0.5), dt} = 0 (μ 3 = 0.5) pt = M (μ 1 = 0.5), when dpt = Z in _{(μ 2 = 0.5), dt} = 0.5 (μ ₃ = 0.5) In the above rules and rules, both the rule and the rule are dt = 0, and their conformity is both μ ₃ = 0.5. Therefore, the conformity μ ₃ of dt = 0 is set to 0.5. . Here, with respect to dt having the same value, if it has a different fitness mu ₃ is a largest value and mu _3.

Therefore, the change amount dt of the target temperature at the outlet of the four-way valve dt
Is calculated by the following equation 1 for calculating the weighted average. In this case, dt = 0.5 is obtained. Thus, a value obtained by adding 0.5 ° C. to the current target temperature becomes the correction temperature.

[0027]

(Equation 1)

Next, the calculation of the valve operation amount by fuzzy inference in the valve operation amount calculation section 14 will be described.

First, as an antecedent part of the fuzzy inference, a temperature difference between the corrected temperature calculated by the corrected temperature calculating unit 13 and the four-way valve outlet temperature, that is, a deviation e (e = corrected temperature−four-way valve outlet temperature) and , And a change amount de of the deviation, and a change amount dv of the valve operation of the electronic expansion valve is defined as a consequent part.
Note that de = 0 is stored in the ROM 15 in advance as an initial value of the change amount de.

[0030] Specifically, as matter membership functions before representing the fit mu ₄ for the deviation e, as shown in FIG. 5,
Function NB applied when deviation e is -4 ° C or less, deviation
Function NS applied when e is −8 ° C. to 0 ° C., and deviation e is −
Function ZS ₁ applied when 4 ° C. to 4 ° C., deviation e is 0 ° C. to 8
A function PS to be applied in the case of ° C. and a function PB to be applied in case the deviation e is 4 ° C. or more are defined and stored in the ROM 15.

Also, the degree of conformity μ to the variation amount de of the deviation is_Five
As an antecedent membership function representing
Function N applied when the change amount de is -1.5 ° C or less
B, a function N applied when the amount of change de is −3 ° C. to 0 ° C.
S, the function applied when the variation de is -1.5 ℃ ～ 1.5 ℃
ZS, function PS applied when the variation de is 0 ° C to 3 ° C
_Two, The function PB applied when the change amount de is equal to or more than 1.5 ° C.
Are defined and stored in the ROM 15.

[0032] Then, the change amount dv of the valve operation of the electronic expansion valve is consequent on the basis of the control rule shown in FIG. 7 which is stored in the ROM 15, the fitness mu ₄ of the antecedent membership functions , it is calculated from μ _5.

Therefore, according to the above definition, for example, when the deviation e is −5 ° C. and the change amount de is 0.75 ° C., the deviation e
Antecedent adaptation degree mu ₄ for the NB: 0.25, NS: 0.75, Z
R: 0, PS: 0, PB: 0 , and the the antecedent adaptation degree mu ₅ with respect to the change amount de deviation NB: 0, NS: 0, ZR: 0.5, P
S: 0.5, PB: 0 As a result, the following four rules are established. Then, for the following four rules, similarly to the case of the above-described correction temperature calculation, MIN-MAX
By applying the method, the smaller of the conformity μ ₄ and μ ₅ of the antecedent part is defined as the conformity of the entire antecedent part, that is, the conformity μ _{6 of the} consequent part.

E = NB (μ ₄ = 0.25), de = PS (μ ₅ =
0.5), dv = 0 (μ ₆ = 0.25) e = NS (μ ₄ = 0.75), de = PS (μ ₅ = 0.5), dv = 0 (μ ₆ = 0.5) e = NB (μ ₄ = 0.25), de = when PB of _{(μ 5 = 0.5), dv} = -1 (μ 6 = 0.25) e = NS (μ 4 = 0.75), when de = PB of (μ ₅ = 0.5), dv = -1 (μ ₆ = 0.5) in the rule-above, rules, and rules are dv = 0 are both adaptability because better rule is large, the fitness mu ₆ of dv = 0 to 0.5. Also, the rules,
And rules are dv = -1 both its adaptability because better rule is large, and adaptability mu ₆ 0.5 of dv = -1.

Accordingly, the change amount dv of the valve operation of the electronic expansion valve is
Is calculated by the following equation 2 for calculating the weighted average. In this case, dv = −0.5 is obtained. In the present embodiment, a value obtained by rounding off the calculated dv value is used as the valve operation amount V. In this case, V = −1, and the stepping motor is reversed by one step, and the current electronic expansion valve 4 The degree of opening and closing is reduced by one step.

[0036]

(Equation 2)

Next, the operation of the refrigerant flow control device of the present invention having the above configuration will be described with reference to the flowchart of FIG.

First, the change amount dpt of the four-way valve outlet temperature is initially set to dpt = 0, and the change amount of the deviation de = 0 is set (S101).
Is operated to detect the four-way valve outlet temperature pt (S103).

Next, the four-way valve outlet temperature pt detected by the temperature detector 10, the amount of change dpt, and the target temperature T stored in the target temperature storage 12 are supplied to the correction temperature calculator 13.
The correction temperature Tc is calculated by the above fuzzy inference (S10
Five).

Then, the calculated correction temperature Tc is stored in the target temperature storage unit 12 as a new target temperature T (S10).
7), and proceed to step S109.

In step S109, it is determined whether or not the routine is an initial routine. In the case of YES, the process proceeds to step S111, in which a deviation e is calculated from the correction temperature Tc and the four-way valve outlet temperature pt. The deviation e and the variation de = 0 of the deviation e are supplied, and the process proceeds to step S115.

On the other hand, in the case of NO in step S109, the process proceeds to step S113, the correction temperature Tc, the four-way valve outlet temperature pt, and deviation e from the previous deviation e _0, and the variation of the deviation e
De (de = e−e ₀ ) is calculated, the calculation result is supplied to the valve operation amount calculation unit 14, and the process proceeds to step S115.

Then, in the next step S115, the deviation e,
The change amount dv of the valve operation is calculated by the above-described fuzzy inference using the change amount de of the deviation e, and the value obtained by rounding off the dv value is set as the valve operation amount V, and the process proceeds to step S117.

In step S117, the electronic expansion valve 4 is driven based on the valve operation amount V calculated in step S115, and the process proceeds to step S119.

In step S119, it is determined whether or not a continuous operation command is being output. If YES, the process proceeds to step S121,
The detection operation by the temperature detection unit 10 is performed, and the four-way valve outlet temperature
While detecting pt, the change amount dpt (dpt = detected four-way valve outlet temperature-previous four-way valve outlet temperature) of the four-way valve outlet temperature is calculated from the detected four-way valve outlet temperature and the previous four-way valve outlet temperature,
Returning to step S105, the above steps S105 to S121
Is performed.

On the other hand, if NO in step S119, the operation ends.

As described above, in the present embodiment, the correction temperature calculation unit 13 calculates the four-way valve outlet temperature, that is, the control target temperature of the refrigerant temperature on the discharge side of the compressor 3 by the actual four-way valve outlet temperature and its actual temperature. Since the temperature is changed based on the amount of change in the temperature, the temperature is sequentially set to a target temperature corresponding to the refrigerant dynamic characteristic, and the flow rate of the refrigerant can be controlled at a high target temperature near the dangerous temperature during steady operation.

In the above embodiment, the correction temperature calculating section 13
The case where fuzzy inference is used as the method of calculating the correction temperature Tc and the valve operation amount V in the valve operation amount calculation unit 14 has been described. However, the calculation may be performed using other methods, for example, PID control. . However, in this case, since the control parameter is calculated by regarding the control target as being linear, there is a possibility that the tracking of the refrigerant dynamic characteristics may be slightly worse than the control based on the fuzzy inference.

Further, in the above embodiment, the description has been given of the case of the vapor compression type refrigerator in which the connection state of the four-way valve is switched to perform the cooling and heating operation. The present invention is also applicable to the case of a vapor compression refrigerator to be operated.

[0050]

As described above, according to the present invention, the target temperature on the refrigerant discharge side of the compressor, which is a reference for controlling the degree of opening and closing of the electronic expansion valve, is detected at regular intervals by the detected refrigerant temperature on the refrigerant discharge side. , And the amount of change in the detected refrigerant temperature, and is set to a high target temperature in consideration of refrigerant dynamic characteristics.
In addition, at the start of the operation of the refrigerator, the target temperature is set in consideration of the amount of overshoot generated, and at the time of steady operation, it can be set to a higher target temperature.

Therefore, since the optimum target temperature is set in consideration of the individual refrigerant dynamic characteristics, a high refrigerating capacity can be obtained in all vapor compression refrigerators having different models, environmental conditions, pipe lengths and the like.

Further, according to the present invention, not only is the target temperature value corrected based on the detected refrigerant temperature at the refrigerant discharge side of the compressor and the amount of change in the detected refrigerant temperature, but also the corrected temperature calculation is performed. The difference between the corrected temperature calculated by the means and the detected refrigerant temperature at the refrigerant discharge side of the compressor, and the valve operation amount of the electronic expansion valve is calculated based on the amount of change in the difference, so that a more stable electronic device is obtained. The degree of opening and closing of the expansion valve can be controlled.

[Brief description of the drawings]

FIG. 1 is a schematic configuration block diagram of a vapor compression refrigerator showing one embodiment of the present invention.

FIG. 2 is a diagram showing an antecedent membership function of a four-way valve outlet temperature for calculating a change amount of a target temperature by fuzzy inference.

FIG. 3 is a diagram showing an antecedent membership function of a change amount of a four-way valve outlet temperature for calculating a change amount of a target temperature by fuzzy inference.

FIG. 4 is a diagram showing a control rule for calculating a change amount of a target temperature by fuzzy inference.

FIG. 5 is a diagram showing an antecedent membership function of a deviation for calculating a change amount of a valve operation by fuzzy inference.

FIG. 6 is a diagram showing an antecedent membership function of a variation amount of a deviation for calculating a variation amount of a valve operation by fuzzy inference.

FIG. 7 is a diagram showing a control rule for calculating a change amount of a valve operation by fuzzy inference.

FIG. 8 is a flowchart illustrating the operation of the present invention.

FIG. 9 is a conceptual diagram of a refrigerant circuit of a vapor compression refrigerator.

FIG. 10 is a diagram showing a change in refrigerant temperature by a conventional four-way valve outlet temperature control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Indoor heat exchanger 2 Outdoor heat exchanger 3 Compressor 4 Electronic expansion valve 5 Outdoor unit 6 Indoor unit 7 Refrigerant piping 8 Piping 9 Four-way valve 10 Temperature detection unit 11 Control unit 12 Target temperature storage unit 13 Correction temperature calculation unit 14 valve Operation amount calculator 15 ROM

Claims (3)

(57) [Claims] 1. A compressor, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger connected by a refrigerant pipe, and an opening / closing degree of the electronic expansion valve based on a refrigerant temperature at a refrigerant discharge side of the compressor. A temperature detecting means for detecting the refrigerant temperature at regular time intervals; a refrigerant temperature detected by the temperature detecting means; and a change amount of the refrigerant temperature based on a change amount of the detected refrigerant temperature. A correction temperature calculating unit that calculates a change amount of the target temperature, corrects and outputs the target temperature according to the change amount, and stores a preset target temperature of the refrigerant temperature, and calculates the correction temperature by the correction temperature calculation unit. Target temperature storage means for storing the corrected temperature as a new target temperature, and controlling the degree of opening and closing of the electronic expansion valve according to a difference between the corrected temperature calculated by the corrected temperature calculation means and the detected refrigerant temperature. And a means for controlling the vapor compression type refrigerator. 2. A compressor, an outdoor heat exchanger, an electronic expansion valve, and an indoor heat exchanger connected by a refrigerant pipe, and an opening / closing degree of the electronic expansion valve based on a refrigerant temperature at a refrigerant discharge side of the compressor. A temperature detecting means for detecting the refrigerant temperature at regular time intervals; a refrigerant temperature detected by the temperature detecting means; and a change amount of the refrigerant temperature based on a change amount of the detected refrigerant temperature. A correction temperature calculating unit that calculates a change amount of the target temperature, corrects and outputs the target temperature according to the change amount, and stores a preset target temperature of the refrigerant temperature, and calculates the correction temperature by the correction temperature calculation unit. Target temperature storage means for storing the corrected temperature as a new target temperature, a difference between the corrected temperature calculated by the corrected temperature calculation means and the detected refrigerant temperature, and a change amount of the difference, and calculating the difference. Valve operation amount calculation means for calculating the valve operation amount of the electronic expansion valve based on the output result; and means for controlling the opening / closing degree of the electronic expansion valve according to the valve operation amount calculated by the valve operation amount calculation means. And a vapor compression refrigerator. 3. The vapor compression refrigerator according to claim 2, wherein the correction temperature calculation means and the valve operation amount calculation means calculate the correction temperature and the valve operation amount, respectively, by fuzzy inference.