JPH08285383A - Fast cooling control method and device in freezing system - Google Patents

Abstract

PURPOSE: To provide a fast cooling control method and a fast cooling control device in a freezing cycle in which a cooling speed can be increased and a liquid back flow is hardly produced. CONSTITUTION: An over-heating degree calculation means 92a-1 calculates an over- heating degree in response to signals obtained from an evaporator outlet temperature sensor 6 and an evaporator inlet temperature sensor 7. Then, a valve opening degree calculation means 92a-2 compares this measured super-heating degree with an super- heating set value so as to calculate a degree of opening of the valve. An upper or lower valve opening degree limit calculation means 92a-3 calculates an upper or a lower limit value of a valve opening degree at each of the temperatures within a refrigerator detected by a refrigerator temperature sensor 8 in reference to various set values such as a capability of an electric proportional expansion valve 3, a requisite capability, an evaporating temperature and a condensing temperature or the like set in separate from a super-heating degree set value. A comparing means 92a-4 compares an upper or a lower limit value of a valve opening degree calculated by the calculation means 92a-3 with a valve opening degree calculated by the calculation means 92a-2, a result of comparison is sent to a valve driving part 5 so as to drive an expansion valve 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rapid cooling control method and device in a refrigeration system, and more particularly, to a valve opening degree of an electric proportional expansion valve which is a difference between a set superheat degree and an actual superheat degree. The present invention relates to a method and apparatus for controlling based on a signal obtained by performing a proportional integral derivative (PID) operation.

[0002]

2. Description of the Related Art Conventionally, as a refrigeration system for implementing such a control method, a refrigerating refrigerant compressor, a condenser, an electric proportional expansion valve and an evaporator are annularly connected by piping to compress and condense the refrigerant. It is well known to carry out a refrigeration cycle in which expansion under reduced pressure and evaporation and vaporization are performed. The opening of the reversible proportional expansion valve is adjusted by a drive source such as an electromagnet or a pulse motor according to the input signal, the temperature at the outlet side and the temperature at the inlet side of the evaporator are detected by temperature sensors, and the output of each temperature sensor The control unit controls the drive source based on the above.

The control unit calculates the degree of superheat measured by taking the difference between the evaporator outlet temperature and the refrigerant temperature, that is, the evaporation temperature, based on the signals respectively input from the temperature sensors that detect the temperatures at the outlet side and the inlet side of the evaporator. Then, the deviation signal calculated from the difference between the measured superheat degree and the set superheat degree is corrected in accordance with the PID operation to obtain the adjustment signal, and the operation amount is controlled based on the adjustment signal, that is, the expansion valve is opened. The opening degree of the expansion valve is controlled and the refrigerant flow rate of the refrigeration system is adjusted by applying a valve opening degree adjustment signal that gives the number of pulses to the drive source.

By the way, since the cooling rate per unit time is required in the rapid cooling, the superheat degree is set so that the evaporator can be efficiently operated when the load is large. However, due to the rapid decrease in load accompanying this rapid cooling, the problem of liquid back occurs. In order to solve this liquid back problem, conventionally, there is a method of automatically adjusting the set superheat degree to an optimum value that does not always cause liquid back and cooling.

[0005]

However, in this method, in the process of calculating the optimum degree of superheat, the amount of liquid is excessively fed and the cooling becomes stepwise, which takes time and is not suitable for rapid cooling. There's a problem.

Therefore, the present invention has been made in view of the above problems.
An object of the present invention is to provide a rapid cooling control method and device for a refrigeration cycle, which can increase the cooling rate and is less likely to cause liquid back.

[0007]

To achieve the above object, a rapid cooling control method in a refrigerating system according to the present invention comprises a refrigerating refrigerant compressor, a condenser, an electric proportional expansion valve and an evaporator, which are connected by piping. Compressed refrigerant, connected in a ring
Condensation liquefaction, reduced pressure expansion, evaporative vaporization is performed, and the superheat degree is calculated based on a signal from a temperature sensor mounted at the outlet and the inlet of the evaporator, and the calculated measured superheat degree and a preset superheat degree set value. To calculate the valve opening of the electric proportional expansion valve, and operate the valve drive unit by a signal according to the calculated valve opening to adjust the opening of the reversible proportional expansion valve. In the rapid cooling control method as described above, the internal temperature set separately from the superheat degree setting value, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, from various setting values such as condensation temperature, The upper limit value and the lower limit value of the valve opening degree at each temperature are calculated, the upper limit value and the lower limit value of the valve opening degree are compared with the calculated valve opening degree, and the comparison result is sent to the valve drive section, It is characterized in that the electric proportional expansion valve is driven. .

It is characterized in that the upper limit value and the lower limit value of the valve opening degree are set to a value which is a superheat degree obtained by adding a predetermined value to the set superheat degree which is the superheat degree at the final temperature.

When the actual superheat degree is larger than the superheat degree obtained by adding a predetermined value to the set superheat degree, the upper limit value of the valve opening is recalculated so that the superheat degree becomes a superheat degree obtained by adding a predetermined value to the set superheat degree. It is characterized in that the valve opening is corrected.

When the calculated valve opening exceeds the upper limit of the valve opening, the reversible proportional expansion valve is not operated and the opening is fixed to the upper limit.

In order to achieve the above object, the rapid cooling control device in the refrigerating system according to the present invention is connected in an annular shape by piping as shown in the basic configuration diagram of FIG.
Refrigerant refrigerant compressor 1, condenser 2, condenser 2, motorized proportional expansion valve 3 and evaporator 4 for compressing, condensing and liquefying, decompressing and evaporating and evaporating, and temperature sensor 6 attached to the outlet and inlet of said evaporator. , 7 for calculating the degree of superheat on the basis of signals from the superheat degree, and a valve opening degree for calculating the valve opening degree by comparing the calculated measured superheat degree with a preset superheat degree set value. In the quick cooling control device in the refrigeration system, which operates the valve drive unit 5 by the operation means 92a-2 and the signal according to the calculated valve opening degree to adjust the opening degree of the reversible proportional expansion valve. The inside temperature detected by the inside temperature sensor 8 from various set values such as the inside temperature set separately from the superheat degree set value, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, and the condensation temperature. Upper and lower limit of valve opening at each temperature of A valve opening upper / lower limit calculating means 92a-3, an upper limit value and a lower limit value of the valve opening calculated by the valve opening upper / lower limit calculating means, and the valve opening calculated by the valve opening calculating means. And a comparison means 92a-4 for driving the electric proportional expansion valve by sending the comparison result to the valve drive section.

[0012]

In the method of the above construction, the refrigerating refrigerant compressor, the condenser, the electric proportional expansion valve and the evaporator which are annularly connected by the pipe perform compression, condensation liquefaction, decompression expansion and evaporative evaporation of the refrigerant. The superheat degree is calculated based on the signals from the temperature sensors installed at the outlet and inlet of the evaporator, and the calculated superheat degree is compared with the preset superheat set value to determine the valve of the electric proportional expansion valve. The opening is calculated, and the valve drive unit is operated by a signal according to the calculated valve opening to adjust the opening of the reversible proportional expansion valve.

In particular, the opening temperature for adjusting the reversible proportional expansion valve is set separately from the superheat degree setting value, the electric proportional expansion valve capacity, the required capacity, the evaporation temperature,
Compares the upper and lower limit values of the valve opening at each temperature inside the store calculated from various set values such as condensation temperature and sends the comparison result to the valve drive unit to drive the electric proportional expansion valve. As a result, the cooling rate can be improved by keeping the refrigerant in a state where it is easily evaporated.

Further, since the upper limit value and the lower limit value of the valve opening degree are set to a value which is a superheat degree obtained by adding a predetermined value to the set superheat degree which is the superheat degree at the final temperature, the valve is closed. The cooling rate can be improved by making the refrigerant always evaporate easily, and liquid back hardly occurs.

Further, when the actual degree of superheat is greater than the degree of superheat obtained by adding a predetermined value to the set degree of superheat, the upper limit value of the valve opening is recalculated so that the degree of superheat becomes a value obtained by adding a predetermined value to the set degree of superheat. The valve opening is corrected to, or when the calculated valve opening exceeds the upper limit of the valve opening, the reversible proportional expansion valve is not operated and the opening is fixed to the upper limit. The valve is prevented from opening and closing extremely in response to a sudden change in the degree of superheat caused by disturbance, and stable operation is possible.

In the apparatus having the above-mentioned structure, particularly the valve opening upper / lower limit calculation means 92a-3 is set separately from the superheat degree set value, the inside temperature, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, From various set values such as the condensation temperature, the upper and lower limit values of the valve opening degree at each temperature inside the refrigerator detected by the inside temperature sensor 8 are calculated, and the comparing means 92a-4 calculates the valve opening upper and lower limit calculating means. The upper limit value and the lower limit value of the valve opening calculated by the above are compared with the valve opening calculated by the valve opening calculating means 92a-2, and the comparison result is sent to the valve drive unit 5 for electric proportional expansion. Since the valve is driven, the cooling rate can be improved by keeping the refrigerant in a state where it is easily evaporated.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an apparatus for carrying out the method according to the invention for controlling the rapid cooling of a refrigeration cycle, in which 1 is a refrigerating refrigerant compressor, 2 is a condenser, 3 is a motorized proportional expansion valve,
Reference numeral 4 denotes an evaporator, which constitutes a refrigerating device by being connected in an annular shape by pipes to form a known cycle of compressing, condensing and liquefying a refrigerant, decompressing (expanding), and evaporatively vaporizing.
Reference numeral 5 is a drive source such as an electromagnet or a pulse motor for adjusting the opening degree of the reversible proportional expansion valve 3 according to an input signal, and 6 and 7 are temperature sensors for detecting the temperatures of the outlet side and the inlet side of the evaporator 4, respectively. , 8 are temperature sensors for detecting the temperature in the freezer, 9
Is a control unit to which the temperature sensors 6, 7 and 8 are connected and which controls the drive source 5 based on the output thereof.

The control unit 9 determines the difference between the evaporator outlet temperature and the refrigerant temperature, that is, the evaporator inlet temperature, by the signals input from the temperature sensors 6 and 7 for detecting the temperatures on the outlet side and the inlet side of the evaporator 4, respectively. Then, the measured superheat degree is calculated, the deviation signal calculated by the difference between the measured superheat degree and the set superheat degree is corrected according to the PID operation to obtain the adjustment signal, and the operation amount is controlled based on the adjustment signal. That is,
By applying a valve opening adjustment signal that gives the valve driving unit 5 the number of pulses for opening the expansion valve 3, the opening of the electric proportional expansion valve 3 is controlled and the refrigerant flow rate of the refrigeration system is adjusted.

FIG. 3 shows the internal construction of the control unit 9, in which reference numeral 91 is A / D for A / D converting signals from the evaporator outlet temperature sensor 6, the inlet temperature sensor 7 and the inside temperature sensor 8. The D converter, 92 is a microcomputer that operates according to a predetermined program, and the microcomputer 92 is a rewritable unit having a central processing unit 92a, a ROM 92b that stores programs and various fixed data, and various data areas and work areas. RAM9
2c. The CPU 92a calculates the superheat degree based on the signals from the temperature sensors 6 and 7, compares the calculated measured superheat degree with the preset superheat degree set value stored in a predetermined area in the ROM 92b, and opens the valve. Calculate the degree.

The CPU 92a also sets various values such as the internal compartment temperature set separately from the superheat setting value and stored in a predetermined area in the ROM 92b, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, the condensation temperature. From the set value, the upper limit value and the lower limit value of the valve opening degree at each temperature in the refrigerator are calculated. Then, the opening degree calculated by this calculation is set on the assumption of a value such that the superheat degree at the final temperature is equal to the set superheat degree + α. Note that α
Is stored in a predetermined area of the ROM 92b, which is changed by the refrigeration cycle system. Moreover, the CPU 92a
Compares the openings calculated as described above and sends the comparison result to the valve drive unit 5 to operate the electric proportional expansion valve 3.

At this time, when the calculated valve opening exceeds the upper limit value and the lower limit value of the valve opening at the temperature at that time, the valve is not operated and is fixed at the upper limit value. However, if the actual degree of superheat is greater than the set degree of superheat + α, the upper limit calculation is performed again to set the degree of superheat to the set value + α.
Modify so that By performing this calculation momentarily as the temperature inside the refrigerator decreases, the inside of the refrigerator can be cooled without causing the phenomenon of reversal of the degree of superheat.

FIG. 4 is a graph showing changes in the upper limit value and the lower limit value of the valve opening obtained by calculation with respect to the inside temperature, and as can be seen from the graph shown in the figure, the curve a shows a decrease in the inside temperature. The curve b indicates that the upper limit opening is decreased by the curve, and the curve b indicates that the lower limit opening is decreased by the decrease of the internal temperature. The reason why the lower limit opening is increased when the internal cold storage temperature is high is to prevent the electric proportional expansion valve 3 from being closed too much.

As described above, when the temperature inside the refrigerator is high, the upper limit value of the valve opening is set to a lower opening (the opening at which the degree of superheat becomes a value obtained by adding a predetermined value to the set degree of superheat). The upper limit value is lowered as the inside temperature decreases, and finally the engine can be operated at the set overheat. This utilizes the characteristic that the initial superheat at the evaporator outlet in the initial stage where the rapid cooling load is large is larger than the set superheat in the final stage where the rapid cooling load is small. Although the operation will be slightly overheated, it is possible to prevent the valve closing operation due to an excessive amount of liquid, so it is possible to increase the cooling speed and shorten the time to obtain the final cooling temperature. it can.

The details of the operation outlined above are described in the ROM 9
This will be described below with reference to the flowcharts of FIGS. 5 and 6 showing the processing performed by the CPU 92a according to the program stored in 2b. The CPU 92a starts its operation when the power is turned on, and performs initial setting in the first step S1. As the initial setting, various set values such as the inside temperature stored in the ROM 92b, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, the condensation temperature, the degree of supercooling, and the degree of superheat are set in the RAM 92c. It is done by writing in the area.

Subsequently, the process proceeds to step S2, it is determined whether or not there is activation by the operation of an activation switch (not shown), and the process waits until this determination becomes YES. When the start operation is performed, the process proceeds to step S3, where a signal corresponding to the initial opening is sent to the valve drive unit 5 to perform the operation of setting the initial opening of the electric proportional expansion valve 3, and the electric driving is performed. The proportional expansion valve 3 is operated. After that, the process proceeds to step S4, where the signals from the sensors 6 to 8 are A / D converted and the sensor data SG (evaporator outlet temperature), SL (evaporator inlet temperature) and SR (internal chamber temperature).
Read as. Next, the process proceeds to step S5 and the inside temperature S
The valve opening upper limit value OL and the valve opening lower limit value CL corresponding to R are calculated and obtained.

The upper and lower limit values of the valve opening are calculated so that the capacity change tendency of the refrigerator at each evaporation temperature and the capacity of the expansion valve are programmed in advance to satisfy the capacity required by the customer. In this calculation, valve opening (number of pulses)
Select one of the valve types such as types A to C in the graph of FIG. next,
Enter the evaporation temperature along with the required capacity. The valve capacity of FIG. 7 and the capacity change tendency of FIG. 8 showing a graph of the refrigeration function power with respect to the evaporation temperature are programmed in advance as described above. Therefore, the opening degree of the expansion valve at each evaporation temperature can be calculated from the above conditions, and the upper and lower limit opening degree can be determined. However, since the refrigeration function power changes depending on the condensing temperature and the expansion valve capacity changes depending on the degree of supercooling, the condensation temperature and degree of subcooling are actually input and corrected.

By the processing of this step S5, the CPU 9
2a is an inside temperature detected by the inside temperature sensor 8 from various set values such as the inside temperature set separately from the superheat setting value, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, and the condensation temperature. Functioning as the valve opening upper / lower limit calculating means 92a-3 for calculating the upper limit value and the lower limit value of the valve opening degree at each temperature.

Thereafter, the process proceeds to step S6, where the superheat degree SHT is calculated by the following equation. SHT = SG-SL Through the process of step S6, the CPU 92a calculates the superheat degree based on the signals from the temperature sensors 6 and 7 mounted at the outlet and the inlet of the evaporator 4, and the superheat degree calculating means 92a-.
Functioning as 1.

In the process of step S6, the degree of superheat S
After obtaining HT, the process proceeds to step S7, where the superheat degree SH
It is determined whether T is smaller than the superheat degree set value SH.
As a result of the determination in step S7, if SH <SHT, the process proceeds to step S8, and the valve opening operation value ΔEV _n is calculated by PID. If SH> SHT, the process proceeds to step S9, and the valve closing operation value ΔEV _n is calculated by PID calculation. After obtaining each, the process proceeds to step S10. When SH = SHT, the process directly proceeds to step S10. Through the processing of steps S7 to S9, the CPU 92a functions as a valve opening degree calculation unit 92a-2 that calculates the valve opening degree by comparing the calculated measured superheat degree with a preset superheat degree set value.

In step S10, the current valve opening EV _n is calculated by the following equation. EV _n = EV _{n -1} + ΔEV _n

[0031] Then the process proceeds to step S11 valve opening EV _n at the present time is determined whether larger than the valve-opening upper limit value OL. When the determination in step S11 is NO, that is, when the current valve opening EV _n is smaller than the valve opening upper limit value OL, which is small, the process proceeds to step S12.
_It is determined whether _n is smaller than the valve opening lower limit CL.
When the determination in step S12 is NO, that is, when the valve opening lower limit value CL is smaller than the current valve opening EV _n , the process proceeds to step S13, in which the valve opening obtained by the PID calculation in steps S8 and S9 is performed. After the valve opening / closing operation is performed with the operation value ΔEV _n and the valve closing operation value ΔEV _n , the process returns to step S4. Step S11
Through the processing from S13 to S13, the CPU 92a compares the upper limit value and the lower limit value of the valve opening degree with the calculated valve opening degree, sends the comparison result to the valve drive section, and drives the electric proportional expansion valve 3. It functions as the comparison means 92a-4.

When the determination in step S11 is YES, that is, when the current valve opening EV is larger than the valve opening upper limit value OL, the routine proceeds to step S14, where the value obtained by adding the predetermined value α to the superheat degree set value SH is the superheat degree. It is determined whether it is less than SHT. When the determination in step S14 is YES, that is, when the value obtained by adding the predetermined value α to the superheat degree set value SH is less than the superheat degree SHT, the routine proceeds to step S15, where the valve opening upper limit value OL and the valve opening lower limit value CL are set. After recalculation, the process proceeds to step S16. When the determination in step S14 is NO, that is, when the superheat degree SHT is larger than a value obtained by adding the predetermined value α to the superheat degree set value SH, step S16 is performed.
Proceed to 16. In step S16, the process returns to step S4 without performing the valve opening / closing operation.

The determination in step S12 is YES.
When the current valve opening EV _n is less than the valve opening lower limit CL, the process proceeds to step S17 to start the liquid back monitoring process, and then proceeds to step S16 without performing the valve opening / closing operation in step S4. Return to.

[0034]

As described above, according to the method of the present invention, the opening for adjusting the reversible proportional expansion valve is set separately from the superheat degree set value, the internal temperature, the electric proportional type The expansion valve capacity, required capacity, evaporation temperature, condensation temperature, etc. are compared with the upper and lower limit values of the valve opening at each temperature in the warehouse calculated from various setting values, and the comparison result is sent to the valve drive unit. Since the electrically driven proportional expansion valve is driven, the cooling rate can be improved by keeping the refrigerant easily evaporated.

Further, since the upper limit value and the lower limit value of the valve opening degree are set to the superheat value obtained by adding a predetermined value to the set superheat degree which is the superheat degree at the final temperature, The cooling rate can be improved by making the refrigerant always evaporate easily, and liquid back is difficult.

Further, when the actual superheat degree is larger than the superheat degree obtained by adding a predetermined value to the set superheat degree, the upper limit value of the valve opening degree is calculated again so that the superheat degree becomes the superheat degree obtained by adding the predetermined value to the set superheat degree. The valve opening is corrected to, or when the calculated valve opening exceeds the upper limit of the valve opening, the reversible proportional expansion valve is not operated and the opening is fixed to the upper limit. The valve is prevented from opening and closing extremely in response to a sudden change in the degree of superheat caused by disturbance, and stable operation is possible.

Further, according to the apparatus of the present invention described above, various settings such as the inside temperature set separately from the superheat degree set value, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature and the condensation temperature are set. Calculates the upper and lower limit values of the valve opening at each temperature inside the refrigerator detected by the internal temperature sensor, and compares the calculated upper and lower limit values of the valve opening with the calculated valve opening. Since the comparison result is sent to drive the valve, the cooling rate can be improved by keeping the refrigerant in a state where it is easily evaporated.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a rapid cooling control device in a refrigeration system according to the present invention.

FIG. 2 is a diagram showing a configuration of a refrigeration system to which the device according to the present invention is applied.

3 is a diagram showing a circuit configuration of a control unit in FIG.

FIG. 4 is a graph for explaining a feature according to the present invention.

FIG. 5 is a flowchart showing a part of processing performed by a CPU in FIG. 3 according to a predetermined program.

FIG. 6 is a flowchart showing another part of the processing performed by the CPU in FIG. 3 according to a predetermined program.

FIG. 7 is a graph showing the relationship between the valve opening (pulse number) and expansion valve capacity.

FIG. 8 is a graph showing the tendency of capacity change, which is the relationship between the refrigeration functional power and the evaporation temperature.

[Explanation of symbols]

 1 Refrigerant Refrigerant Compressor 2 Condenser 3 Electric Proportional Expansion Valve 4 Evaporator 5 Valve Drive 6 Evaporator Outlet Temperature Sensor 7 Evaporator Inlet Temperature Sensor 8 In-Cylinder Temperature Sensor 92a-1 Superheat Calculation Unit (CPU) 92a -2 valve opening calculation means (CPU) 92a-3 valve opening upper and lower limit calculation means (CPU) 92a-4 comparison means (CPU)

Claims (5)

[Claims] 1. A refrigerating refrigerant compressor, a condenser, a motor-operated proportional expansion valve and an evaporator are connected in an annular shape by pipes to perform refrigerant compression, condensation liquefaction, decompression expansion and evaporative vaporization, and the outlet of the evaporator. And a superheat degree is calculated based on a signal from a temperature sensor mounted at the inlet, and the calculated measured superheat degree is compared with a preset superheat degree set value to determine the valve opening degree of the electric proportional expansion valve. In the rapid cooling control method in a refrigeration system, which is operated to adjust the opening of the reversible proportional expansion valve by operating a valve drive unit with a signal according to the calculated valve opening, The upper and lower limit values of the valve opening at each temperature in the refrigerator are calculated from various settings such as the temperature inside the refrigerator, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, the condensation temperature, etc. Calculate the upper and lower limits of the valve opening and Comparing the computed valve opening, and sends the comparison result to the valve driving unit, rapid cooling control method in a refrigeration system characterized in that so as to drive the electric proportional expansion valve. 2. An upper limit value and a lower limit value of the valve opening degree are set to values that are a superheat degree obtained by adding a predetermined value to a set superheat degree that is a superheat degree at a final temperature. Item 1
A rapid cooling control method in the refrigeration system described. 3. When the actual superheat degree is larger than the superheat degree obtained by adding a predetermined value to the set superheat degree, the upper limit value of the valve opening degree is recalculated to become the superheat degree obtained by adding a predetermined value to the set superheat degree. The rapid cooling control method in the refrigeration system according to claim 2, wherein the valve opening is corrected as described above. 4. When the calculated valve opening exceeds the upper limit of the valve opening, the reversible proportional expansion valve is not operated and the opening is fixed to the upper limit. The rapid cooling control method in the refrigeration system according to any one of claims 1 to 3. 5. A refrigerating refrigerant compressor, a condenser, a motor-operated proportional expansion valve and an evaporator, which are connected by a pipe in a ring shape and perform compression, condensation liquefaction, decompression expansion and evaporative evaporation of a refrigerant, and an outlet of the evaporator. And a superheat degree calculating means for calculating a superheat degree on the basis of a signal from a temperature sensor attached to the inlet, and the electric proportional expansion valve by comparing the calculated measured superheat degree with a preset superheat degree set value. And a refrigeration system for adjusting the opening of the reversible proportional expansion valve by operating a valve drive unit with a signal according to the calculated valve opening. In the rapid cooling control device in, the temperature inside the refrigerator set separately from the superheat degree set value, the capacity of the electric proportional expansion valve, the required capacity, the evaporation temperature, from various setting values such as the condensation temperature, For each temperature in the chamber detected A valve opening upper and lower limit calculating means for calculating an upper limit value and a lower limit value of the valve opening, and the comparing means, the upper limit value and the lower limit value of the valve opening calculated by the valve opening upper and lower limit calculating means, and Refrigeration characterized by comprising: a comparison means for comparing the valve opening calculated by the valve opening calculating means, and sending the comparison result to a valve drive section to drive the electric proportional expansion valve. Rapid cooling controller in the system.