JP2000146313A - Operation controller for refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an operation controller for a refrigerating machine, which is capable of executing the optimum refrigerating cycle and stabilizing a refrigerating capacity, by a method wherein the delicate control of the opening degree of a motor- driven expansion valve, which approximates the value of conditional characteristic, such as a discharging pipe temperature, to an objective value, is permitted. SOLUTION: In an air conditioner equipped with a refrigerant circulating circuit for circulating refrigerant in the order of a compressor 4, a condenser 5, a motor-driven expansion valve 6, and an evaporator 7, a discharging pipe temperature thermistor 17 for detecting the discharging pipe temperature of the compressor 4, an operation control means 18 for controlling the opening degree of the motor-driven expansion valve 6 so that a discharging pipe temperature, detected at every predetermined period, coincides with an objective value, and an intermediate opening degree control means 19, setting two large and small opening degrees, whose difference becomes the minimum control amount of the motor-driven expansion valve 6 while switching with a predetermined time rate and executing an intermediate opening degree operation, repeating the switching operation of the opening degree between the large opening degree and small opening degree within the period, are provided. According to this method, the intermediate opening degree of two opening degrees is realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an operation control device for a refrigerator having a refrigerant circuit for executing a refrigeration cycle, such as an air conditioner.

[0002]

2. Description of the Related Art An air conditioner is provided with a refrigerant circulation circuit for circulating refrigerant in the order of a compressor, a condenser, an electric expansion valve, and an evaporator. Air conditioning such as cooling and heating. Then, in order for the refrigeration cycle to be performed normally, a state characteristic value indicating an operation state of the refrigerant circuit is detected, and the opening of the electric expansion valve is adjusted so that the detected state characteristic value matches a predetermined target value. The degree is feedback controlled. As the state characteristic value, for example, a discharge temperature of a compressor is selected (for example, JP-A-8-28996).
Since it is difficult to directly detect the discharge temperature, a thermistor is attached to the discharge pipe to detect the discharge pipe temperature.

The electric expansion valve has a structure in which the opening is controlled by a control pulse inputted from the outside. The control amount (change amount) of the opening which can be controlled by one pulse, that is, the change amount of the flow rate is It depends on the performance (control pulse resolution) of the electric expansion valve. FIG. 5 is a graph showing the flow characteristics of the electric expansion valve. The solid line L1 indicates the flow characteristic of the electric expansion valve A, and the broken line L2 indicates the flow characteristic of the electric expansion valve B. Compared with the electric expansion valve B, the electric expansion valve A has a small opening control amount, that is, a change amount of the flow rate that can be controlled by one pulse, and thus enables a fine control of the flow rate. Therefore, it is desirable to use a high-performance valve such as the electric expansion valve A from the viewpoint of finely adjusting the flow rate. However, since it is generally expensive, the electric expansion valve B is preferably used from the viewpoint of cost reduction of the product. Attempts have been made to use inexpensive and low-performance devices such as the above.

[0004]

FIG. 6 is a time chart showing a control state when a low-cost, low-performance electric expansion valve is used. The opening degree control of the electric expansion valve is performed by feedback control in order to make the discharge pipe temperature close to the target discharge pipe temperature TSET while detecting the discharge pipe temperature with a discharge pipe thermistor every predetermined cycle (for example, 20 seconds). . Looking at the change in the discharge pipe temperature accompanying the change in the opening, the control pulse resolution of the electric expansion valve used is coarse, so the flow rate change when the opening changes is large, and the solid line L
As shown by 3, the discharge pipe temperature hunts with a large swell relative to the target discharge pipe temperature TSET. That is,
When the opening is narrowed from En to En-1 to increase the discharge pipe temperature at time t1, the refrigerant pressure increases and the discharge pipe temperature increases, but at time t2, the discharge pipe temperature increases to the target discharge pipe temperature. Since it has risen beyond the predetermined target range set including TSET, the opening degree is now expanded from En-1 to En to lower the discharge pipe temperature. Then, at time t3, the opening has been narrowed again because it has dropped below the target range,
As a result, at time t4, as in the case of time t2, it rises beyond the predetermined target range. The switching of the opening degree is repeated even after time t4, and the discharge pipe temperature hunts accordingly.

As described above, when the variation of the discharge pipe temperature with respect to the control amount of the opening for one pulse in the electric expansion valve is larger than a predetermined target range, hunting of the discharge pipe temperature occurs. As a result, an appropriate refrigeration cycle is not executed, and the degree of intake superheat and air conditioning capacity hunt, resulting in a problem that the entire air conditioner is not stabilized.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional disadvantages, and has as its object to finely control the degree of opening of an electric expansion valve so that a state characteristic value such as a discharge pipe temperature approaches a target value. It is an object of the present invention to provide an operation control device for a refrigerator capable of performing an appropriate refrigeration cycle and stabilizing a refrigeration capacity.

[0007]

Accordingly, the operation control device for a refrigerator according to the present invention comprises a refrigerant circulation circuit for circulating refrigerant in the order of a compressor 4, a condenser 5, an electric expansion valve 6, and an evaporator 7. Characteristic value DO indicating the operating state of the refrigerant circuit, such as the discharge temperature of the compressor 4, in the refrigerator 1.
And the opening degree of the electric expansion valve 6 based on the detection result of the detection means 17 outputted at every predetermined period TTHS so that the state characteristic value DO approaches the target value DOSET. The operation control means 18 to be controlled and the two large and small opening degrees EVMK and EVMK ± 1 whose difference is the minimum control amount of the electric expansion valve 6 are switched and set at a predetermined time ratio. An intermediate opening operation in which the switching operation is repeated within the above-mentioned cycle TTHS is executed,
Thus, an intermediate opening control means 19 for realizing an intermediate opening of the two opening degrees EVMK and EVMK ± 1 is provided.

In the operation control device for a refrigerator according to the first aspect, the state characteristic value DO such as the discharge temperature of the compressor 4 is detected at a predetermined cycle TTHS, and the state characteristic value DO is set to a predetermined target value DOSET. Is controlled so as to approach. Therefore, in the normal opening control, it is determined whether to maintain or change the opening every predetermined period TTHS based on the detected state characteristic value DO, and the set opening is maintained during the period TTHS. . On the other hand, in the intermediate opening operation, the two opening degrees EVMK and EVMK ± 1 are switched and set at a predetermined time ratio, and the switching operation of the opening degree is repeatedly performed in the cycle TTHS. Looking at the entire TTHS period, the above two opening degrees EV
It is possible to realize almost the same operating state (refrigerant flow rate) as when an intermediate opening degree between MK and EVMK ± 1 is set. Therefore, since the opening can be controlled with a control amount smaller than the original minimum control amount of the electric expansion valve 6, fine operation control becomes possible. Also, even when an inexpensive and low-performance electric expansion valve with a relatively large minimum control amount is used, it is almost the same as when an expensive and high-performance electric expansion valve with a small minimum control amount is used. Thus, detailed control of the operating state is possible, and the cost of the product can be reduced.

The operation control device for a refrigerator according to claim 2 is
The intermediate opening control means 19 detects the detected state characteristic value DO.
Is characterized in that the intermediate opening operation is executed when the state within the target vicinity including the target value DOSET continues for a predetermined time.

In the second aspect, the detected state characteristic value D
When O stays within the range close to the target value for a predetermined time, that is, when the opening of the electric expansion valve 6 is maintained for a predetermined time, and the opening is changed with the original minimum control amount, the target value DOSET is set. , The intermediate opening degree operation is performed. Thereby, the state characteristic value DO
Can be reliably brought closer to the target value DOSET,
An appropriate operation state, that is, an appropriate refrigeration cycle can be executed. Further, the width of the hunting of the state characteristic value DO can be reduced, and the refrigerating capacity can be stabilized.

Further, in the operation control device for a refrigerator according to the third aspect, the time ratio in the opening degree switching operation is larger than the time ratio mathematically obtained corresponding to the intermediate opening to be set. It is characterized in that the time ratio of the small opening is set to be larger.

In the operation control device for a refrigerator according to the third aspect, the time ratio of the small opening degree EVMK-1 is larger than the time ratio mathematically obtained corresponding to the intermediate opening degree to be set. Although this is set, this is because the rate of increase in the refrigerant pressure due to the decrease in the opening degree and the decrease in the refrigerant flow rate is lower than the decrease rate of the refrigerant pressure due to the increase in the opening degree and the increase in the refrigerant flow rate. It is. Therefore, for example, when it is desired to set the opening in the middle of the two openings EVMK and EVMK-1 of large and small mathematically, 0.5 and 0.
5, but taking into account the difference in reaction rate as described above,
For example, the large opening EVMK is set to 0.4, and the small opening EVMK-1 is set to 0.6. Thereby, a desired intermediate opening degree can be realized more reliably.

According to a fourth aspect of the present invention, the operation control device for a refrigerator changes the time ratio in accordance with a difference between the detected state characteristic value DO and the target value DOSET.

In the refrigerator operation control device according to the fourth aspect, the time ratio in the opening degree switching operation is changed in accordance with the difference between the detected state characteristic value DO and the target value DOSET. Compared with the case where the ratio is fixed to a specific value, the state characteristic value DO is more reliably set to the target value D.
OSET can be approached.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, a specific embodiment of an operation control device for a refrigerator according to the present invention will be described in detail with reference to the drawings.

FIG. 1 is a configuration diagram showing a schematic configuration of an air conditioner 1 according to an embodiment of the present invention. The air conditioner 1 includes an outdoor unit 2 and an indoor unit 3. And in the air conditioner 1, in the order in which the refrigerant can circulate,
The compressor 4, the outdoor heat exchanger 5, the electric expansion valve 6 as a pressure reducing mechanism, and the indoor heat exchanger 7 are connected to form a refrigerant circulation circuit.

Specifically, the discharge pipe 4a and the suction pipe 4b of the compressor 4 are connected to a four-way switching valve 8, and the four-way switching valve 8
Has a first gas pipe 9a, an outdoor heat exchanger 5, a first liquid pipe 9b,
The electric expansion valve 6, the second liquid pipe 9c, the indoor heat exchanger 7, and the second gas pipe 9d are sequentially connected in a ring shape. A part of the second liquid pipe 9c is a liquid pipe 10 of the communication pipe, and a part of the second gas pipe 9d is a gas pipe 11 of the communication pipe. Further, a liquid shutoff valve 12 is interposed in the second liquid pipe 9c, and a gas shutoff valve 13 is interposed in the second gas pipe 9d.
An accumulator 14 is interposed in the suction pipe 4b of the compressor 4.

The compressor 4 is controlled by the control unit 16 via the inverter 15 so that the operating frequency can be changed.
This allows the compression capacity to be changed. This control unit 1
Reference numeral 6 denotes a microcomputer which is configured using a microcomputer or the like, and receives detection temperatures from various thermistors such as a discharge pipe temperature thermistor 17 for detecting the temperature of the discharge pipe 4a and an outdoor temperature thermistor (not shown) and an indoor temperature thermistor. Is done. Further, an operation signal from operation means (not shown) is also input to the control unit 16, and the operation state of the air conditioner 1 is determined by the operation signal. The operating state is the start and stop of the air conditioning operation, switching between the cooling operation and the heating operation,
Set temperature, air volume, etc. The operation means is realized by an operation panel connected to the indoor unit 3, a remote control device (abbreviated as a remote control), or the like.

In such an air conditioner 1, a cooling operation or a heating operation can be performed based on an instruction from operation means such as a remote controller. When performing the cooling operation, the four-way switching valve 8 is switched in the solid line direction shown in FIG. 1 to allow the refrigerant to flow from the compressor 4 to the outdoor heat exchanger 5, the electric expansion valve 6, and the indoor heat exchanger 7 in this order. The outdoor heat exchanger 5 functions as a condenser, and the indoor heat exchanger 7 functions as an evaporator. Then, by discharging the heat absorbed by the indoor heat exchanger 7 to the outside of the room via the refrigerant, the temperature in the room is lowered to perform cooling.

On the other hand, when performing the heating operation, the four-way switching valve 8 is switched in the direction of the broken line shown in FIG. 1 to circulate the refrigerant in the direction opposite to that in the cooling operation, and the outdoor heat exchanger 5 is operated. In addition to functioning as an evaporator, the indoor heat exchanger 7 functions as a condenser. Then, the amount of heat absorbed by the outdoor heat exchanger 5 is released into the room through the refrigerant, thereby increasing the temperature of the room and performing heating.

When performing the cooling operation or the heating operation, the control unit 16 determines the refrigerating capacity of the refrigerating cycle performed in the refrigerant circuit based on the indoor temperature, the outdoor temperature, the set temperature, and the like. The opening degree of the electric expansion valve 6 is adjusted by the operation control means 18 so that the refrigeration capacity is exhibited, and an appropriate refrigeration cycle is executed. At this time, whether or not an appropriate refrigeration cycle is being executed is determined based on, for example, whether or not the discharge pipe temperature matches a predetermined target value as a state characteristic value indicating the operation state of the refrigerant circuit. That is, the operation control means 18 takes in the detected temperature of the discharge pipe temperature thermistor 17 at a predetermined cycle, for example, every 20 seconds, and adjusts the opening degree of the electric expansion valve 6 so that the discharge pipe temperature coincides with the target value. Control. It is practically difficult to continue the operation with the discharge pipe temperature completely matched with the target value.
The control is performed so as to fall within the target control range.

Here, the opening of the electric expansion valve 6 is controlled by the control unit 16.
Is controlled by the pulse signal from. For example, +
When one pulse is input on the input side, the electric expansion valve 6 is opened by a predetermined minimum control amount. Conversely, when one pulse is input on the-input side, the electric expansion valve 6 is closed by the minimum control amount. Can be As described above, the opening degree of the electric expansion valve 6 is adjusted stepwise in minimum control amount units. Therefore, when the amount of change in the discharge pipe temperature that changes when the opening is changed by the minimum control amount is, for example, 0.5 degrees, and is smaller than 1 degree in the target control range, the above-described 1 Only by controlling the opening degree in pulse units, control can be performed so that the discharge pipe temperature matches the target value or falls within the target control range. On the other hand, when the change amount of the discharge pipe temperature corresponding to one pulse is, for example, 3 degrees and is equal to or more than 1 degree of the target control range, the above-described desired control cannot be performed only by the opening degree control of one pulse unit. is there.

Therefore, in the air conditioner 1 of the present invention, the intermediate opening degree control means 19 is newly provided, and by executing the intermediate opening degree operation, the difference between the two becomes the minimum control amount of the electric expansion valve 6. Intermediate opening of two opening degrees is realized. The intermediate opening operation is to switch and set two large and small openings at a predetermined time ratio, and to repeat the operation of switching the opening within the above-mentioned cycle (20 seconds). Thereby, it is possible to realize substantially the same refrigerant flow rate (refrigerant pressure) as in the case where an opening degree intermediate between the above two opening degrees is set in the entire cycle period. Hereinafter, the intermediate opening degree operation will be specifically described.

FIG. 2 is a flowchart for explaining the opening control procedure in the control unit 16, and FIG. 3 is a time chart for explaining the intermediate opening operation. First,
The control procedure in the normal operation mode by the operation control means 18 will be described with reference to FIG.

In step S1, the discharge pipe temperature DO is detected based on the output of the discharge pipe temperature thermistor 17. In step S2, the cycle TTHS is determined by a sampling timer.
Start timing.

In the following step S3, it is determined whether or not the opening of the electric expansion valve 6 needs to be changed. Specifically, when the discharge pipe temperature DO is not within the target vicinity range, that is, when | DO-DOSET |> α, it is determined that the opening degree needs to be changed. Here, α is 1 of the electric expansion valve 6.
The value is selected to be smaller than the amount of temperature change with respect to the change in the opening degree of the pulse. For example, if the temperature change is 3 degrees,
α is set twice. That is, the target discharge pipe temperature DOSE
If the difference from T is relatively large and changing the opening by one pulse more closely approaches the target discharge pipe temperature DOSET, it is determined that the opening needs to be changed. Therefore, in this case, the process proceeds to step S5, and the opening degree of the electric expansion valve 6 is changed by one pulse. When DO> DOSET, the opening is increased and D
If O <DOSET, the opening is reduced. Thereafter, the process proceeds to step S6.

On the other hand, if it is determined in step S3 that there is no need to change the opening, the process proceeds to step S4. Step S4
Then, the previously detected discharge pipe temperature DO and the target discharge pipe temperature D
It is determined whether the difference from OSET is equal to or less than α.
If the determination is affirmative, the process proceeds to a virtual intermediate pulse mode described later. Therefore, when the discharge pipe temperature DO is stabilized in the range near the target value, the mode shifts to the virtual intermediate pulse mode. On the other hand, if the determination is negative, that is, if the discharge pipe temperature DO has just entered the range near the target value, it is considered that the temperature change is unstable, and the process proceeds to step S6 to wait until the temperature change becomes stable.

In step S6, it is determined whether the period TTHS has elapsed. If the elapsed time has not elapsed, the changed opening degree or the held opening degree is maintained. If the time has elapsed, the process returns to step S1 again, and the above processing is repeated.

Next, referring to FIGS. 2B and 3,
The intermediate opening operation in the virtual intermediate pulse mode by the intermediate opening control means 19 will be described. In step S7, DO
It is determined whether SET> DO. Target discharge pipe temperature D
If it is higher than the discharge pipe temperature DO detected by OSET,
Proceeding to step S8, as shown in FIG.
In the VIRP1, the current opening EVMK is held, and in the subsequent period TVIRP, the opening EVMK-1 is set smaller by one pulse, and the switching operation between the two large and small openings is repeatedly executed until the period TTHS elapses. As a result, when viewed over the entire cycle TTHS, the opening degrees EVMK and EVMK
It is possible to realize the same state as setting an opening degree intermediate to K-1. Therefore, the discharge pipe temperature can be increased.

On the other hand, when the target discharge pipe temperature DOSET is equal to or lower than the detected discharge pipe temperature DO, the process proceeds to step S10, and as shown in FIG. In the period TVIRP4, the opening EVMK + 1 is set to be larger by one pulse, and
The switching operation of the two large and small opening degrees is repeatedly executed until the period TTHS elapses. Thereby, the period TTHS
As a whole, it is possible to realize the same state as setting an intermediate opening between the opening degrees EVMK and EVMK + 1.
Therefore, the temperature of the discharge pipe can be reduced.

Then, step S9 or step S11
If the period TTHS has elapsed, the process proceeds to step S12, ends the virtual intermediate pulse mode, and returns to step S1 again. At this time, the opening at the end is the corrected opening EVM.
In the case of K-1 or EVMK + 1, the original opening EVMK
Return to This is to prevent a deviation in the opening degree setting when the virtual intermediate pulse mode is executed even in the next cycle TTHS. When the operating frequency of the compressor 4 needs to be largely changed, the operation is switched to the open control because the follow-up performance is low in the feedback control.
The virtual intermediate pulse mode ends.

As described above, according to the present embodiment, it is possible to realize almost the same operating state as the case where the intermediate opening degree is set to an intermediate opening degree between the two opening degrees of the electric expansion valve 6 by the above-described intermediate opening degree operation. The opening can be controlled by a control amount smaller than the original minimum control amount of the electric expansion valve 6, and fine operation control can be performed. Even when an inexpensive and low-performance electric expansion valve is used, the operation state can be controlled in substantially the same manner as when an expensive and high-performance electric expansion valve is used, and the cost of the air conditioner 1 can be reduced. Becomes

Since the intermediate opening operation is performed when the detected discharge pipe temperature DO is approaching the target discharge pipe temperature DOSET, the discharge pipe temperature DO is set to the target discharge pipe temperature DO as shown by the solid line L4 in FIG. The approach can be reliably performed by DOSET, and an appropriate refrigeration cycle can be executed. Furthermore, since the width of the hunting of the discharge pipe temperature can be reduced, the refrigerating capacity (air conditioning capacity) can be stabilized.

By the way, the time ratio TVIRP1: TVIRP2 and TVI in the opening degree switching operation described above.
RP3: TVIRP4 is mathematically obtained in accordance with the intermediate opening to be set, but more precisely, the time ratio of the small opening is set to be larger. This is because the rate of increase in the refrigerant pressure due to the decrease in the opening degree and the decrease in the refrigerant flow rate is lower than the decrease rate of the refrigerant pressure due to the increase in the opening degree and the increase in the refrigerant flow rate.
For example, when an opening in the middle of two large and small openings is to be set, it is mathematically 0.5 and 0.5, but in consideration of the above-described difference in reaction speed, TVIRP1 is set. <
For example, the large opening is set to 0.4 and the small opening is set to 0.6 so that TVIRP2 and TVIRP3> TVIRP4. Thereby, a desired intermediate opening degree can be realized more reliably.

The time ratio may be fixed to a predetermined value or may be set to a predetermined value.
It may be changed in accordance with the temperature difference between O and the target discharge pipe temperature DOSET. When the time ratio can be changed, the optimum intermediate opening corresponding to the temperature difference can be set as compared with the case where the time ratio is fixed, so that the discharge pipe temperature DO can be more reliably brought close to the target discharge pipe temperature DOSET. it can.

In the present embodiment, the case where the intermediate opening operation is performed on the electric expansion valve 6 which is a pressure reducing mechanism has been described. However, the present invention may be applied to an electric expansion valve for gas injection.

[0037]

As described above, according to the operation control device for a refrigerator of the first aspect, the operation of the electric expansion valve is controlled by the intermediate opening operation.
It is possible to realize almost the same operating state as when an intermediate opening between two openings is set, so that the opening can be controlled with a control amount smaller than the original minimum control amount of the electric expansion valve. It becomes possible. In addition, even when an inexpensive and low-performance electric expansion valve is used, it is possible to control the operating state in the same manner as when an expensive and high-performance electric expansion valve is used, thereby reducing the cost of the product. .

According to the second aspect of the present invention, the intermediate opening operation is performed when the detected state characteristic value is approaching the predetermined target value, so that the state characteristic value can be more reliably determined by the target value. , And a proper operation state, that is, a proper refrigeration cycle can be executed.
Further, the hunting width of the state characteristic value can be reduced, so that the refrigerating capacity can be stabilized.

Further, according to the refrigerator operation control device of the third aspect, the time ratio in the opening degree switching operation is set in consideration of the fact that the rising speed of the refrigerant pressure is slower than the decreasing speed. Can be more reliably realized.

According to the refrigerator operation control device of the fourth aspect, since the time ratio in the opening degree switching operation is appropriately changed, the state characteristic value approaches the target value more reliably in a short time. be able to.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a procedure for controlling an opening degree of an electric expansion valve.

FIG. 3 is a time chart for explaining an intermediate opening operation of the electric expansion valve.

FIG. 4 is a time chart showing a change in discharge pipe temperature due to an intermediate opening degree operation.

FIG. 5 is a graph showing a flow rate characteristic of the electric expansion valve.

FIG. 6 is a time chart showing an operation state of the electric expansion valve based on the conventional opening control.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Air conditioner 4 Compressor 5 Outdoor heat exchanger 6 Electric expansion valve 7 Indoor heat exchanger 17 Discharge pipe temperature thermistor 18 Operation control means 19 Intermediate opening degree control means DO Discharge pipe temperature (state characteristic value) DOSET Target discharge pipe temperature (Target value) EVMK opening EVMK-1 opening EVMK + 1 opening

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takao Terauchi 1000, Oya, Okamotocho, Kusatsu-shi, Shiga 2 Daikin Industries, Ltd. Shiga Works

Claims (4)

[Claims] 1. A refrigerator (1) having a refrigerant circulation circuit for circulating refrigerant in the order of a compressor (4), a condenser (5), an electric expansion valve (6), and an evaporator (7). Detecting means (17) for detecting a state characteristic value (DO) indicating the operating state of the refrigerant circuit, such as the discharge temperature of the compressor (4);
And the state characteristic value (D) based on the detection result of the detection means (17) output every predetermined period (TTHS).
Operation control means (18) for controlling the degree of opening of the electric expansion valve (6) so that O) approaches the target value (DOSET);
The two degrees of opening (EVMK) (EVMK ± 1), the difference of which is the minimum control amount of the electric expansion valve (6), are switched and set at a predetermined time ratio. An intermediate opening operation that is repeatedly performed within the above-mentioned cycle (TTHS) is executed.
K) An operation control device for a refrigerator, comprising: an intermediate opening control means (19) for realizing an intermediate opening of (EVMK ± 1). 2. The intermediate opening degree control means (19) is configured to control a state when the detected state characteristic value (DO) is within a target vicinity range including the target value (DOSET) for a predetermined time. The operation control device for a refrigerator according to claim 1, wherein the intermediate opening operation is performed. 3. The time ratio in the magnitude switching operation of the opening is such that a time ratio of a small opening is set to be larger than a time ratio mathematically obtained corresponding to the intermediate opening to be set. The operation control device for a refrigerator according to claim 1 or 2, wherein: 4. The refrigeration apparatus according to claim 1, wherein said time ratio is changed in accordance with a difference between the detected state characteristic value (DO) and said target value (DOSET). Machine operation control device.