JP2010266121A - Cooling apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling apparatus that can prevent a compressor from sucking in a liquid refrigerant by controlling the opening of an electronic expansion valve as predicting the load of cooling a compartment in accordance with the lighting status of a luminaire disposed in the compartment. <P>SOLUTION: The cooling apparatus configured to condition a compartment 10 of an open showcase 11 to a desired temperature by controlling the opening of the electronic expansion valve 13 to control a refrigerant supply to an evaporator 12 disposed in the open showcase 11 includes a lighting control part 33 for controlling the lighting of a luminaire 22 disposed in the compartment 10, and a valve opening setting part 35 for correctively reducing the opening of the electronic expansion valve 13 by a predetermined degree when the lighting control part 33 switches off the luminaire 22. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a cooling device, and more specifically, by adjusting the opening of an electronic expansion valve and controlling the supply of refrigerant to an evaporator disposed in the storage device, the storage device of the storage device is desired. The present invention relates to a cooling device in a temperature state.

  For example, in an open showcase that displays and sells products in a cooled state, an evaporator and an electronic expansion valve are provided inside the compressor, and a compressor and a condenser are provided outside the evaporator. In addition, the storage of the open showcase is maintained at a desired temperature state by circulating the refrigerant through a refrigeration cycle constituted by sequentially connecting a condenser and an electronic expansion valve.

  Specifically, the refrigerant outlet temperature at the outlet of the evaporator and the refrigerant inlet temperature at the inlet of the evaporator are detected, and the superheat degree in the evaporator is calculated by subtracting the inlet temperature from the outlet temperature. The refrigerant supply control is performed on the evaporator by adjusting the opening of the electronic expansion valve based on the deviation between the calculated degree of superheat and a predetermined set degree of superheat. In addition to the refrigerant supply control, the internal temperature of the storage is detected, and the opening of the electronic expansion valve is adjusted based on the deviation between the detected internal temperature and a preset temperature ( For example, see Patent Document 1).

JP 2008-175442 A

  By the way, in the open showcase to which the cooling device as described above is applied, it is general that a lighting device is installed inside the container. This lighting device is in a state where it is possible to take out the product stored in the storage, that is, the store where the open showcase is installed is within business hours, and the user is stored in the storage. It is lit when the product can be taken out, and is turned off when the store cannot take out the product stored in the storage box during off-hours. When the lighting device is turned off, the front opening of the open showcase is generally closed by a cover member called a night cover.

  In this way, when the front opening is closed by the night cover, outside air is prevented from entering the interior of the storage through the front opening. Smaller than when not closed.

  Therefore, even when the front opening is closed by the night cover, if the storage is cooled by the evaporator at the same level as when the front opening is not closed by the night cover, the liquid refrigerant is sufficient in the evaporator. There is a risk of causing a phenomenon of so-called liquid back in which the compressor does not evaporate and the compressor sucks the liquid refrigerant.

  In view of the above circumstances, the present invention predicts the cooling load of the storage according to the lighting state of the lighting device disposed inside the storage, and adjusts the opening of the electronic expansion valve to thereby adjust the compressor. An object of the present invention is to provide a cooling device that can suppress the suction of liquid refrigerant.

  In order to achieve the above object, a cooling device according to claim 1 of the present invention adjusts the opening of an electronic expansion valve and controls supply of refrigerant to an evaporator disposed in the storage device. In the cooling device for bringing the storage of the storage unit into a desired temperature state, when the lighting device is turned off by the lighting control unit that controls the lighting of the lighting device disposed inside the storage, and the lighting control unit Comprises a control means for reducing the opening degree of the electronic expansion valve while performing correction control to increase the opening degree of the electronic expansion valve when the lighting device is turned on by the illumination control means. It is characterized by that.

  The cooling device according to claim 2 of the present invention is the cooling device according to claim 1, wherein the refrigerant inlet temperature at the inlet portion of the evaporator is subtracted from the refrigerant outlet temperature at the outlet portion of the evaporator. When the superheat degree calculation means for calculating the superheat degree in the evaporator is provided, and the control means performs a pull-down operation for cooling the internal temperature of the container to a preset temperature after completion of the defrosting operation, If the degree of superheat calculated by the superheat degree calculation means exceeds a predetermined upper limit value of the superheat degree target value at a time point higher than the set temperature by a predetermined reference temperature, the opening degree of the electronic expansion valve On the other hand, when the degree of superheat calculated by the superheat degree calculation means at the time is in the range of the lower limit value to the upper limit value of the superheat degree target value, the opening degree of the electronic expansion valve is And performing control for lifting.

  In the cooling device according to claim 3 of the present invention, in the above-described claim 2, when the control means performs the pull-down operation, the superheat degree calculated by the superheat degree calculation means is predetermined. If it is less than the lower limit value of the superheat degree target value, it is judged that the compressor sucks the liquid refrigerant, and the opening degree of the electronic expansion valve is reduced.

  According to the present invention, when the lighting device is turned off by the lighting control unit that controls lighting of the lighting device arranged inside the storage, the correction unit determines the opening degree of the electronic expansion valve in advance. Since the correction control is performed to reduce the size by a predetermined amount, the liquid refrigerant can be sufficiently evaporated by the evaporator even when the cooling load inside the container is reduced, and the compressor sucks the liquid refrigerant. Therefore, there is no possibility of causing a so-called liquid back phenomenon. Therefore, the compressor sucks the liquid refrigerant by adjusting the opening of the electronic expansion valve by predicting the cooling load of the storage according to the lighting state of the lighting device arranged inside the storage. There is an effect that this can be suppressed.

FIG. 1 is a conceptual diagram conceptually showing the configuration of a cooling device according to an embodiment of the present invention. FIG. 2 is a chart showing an example of the relationship between the degree of superheat in the evaporator, the operating state determined by the state determination unit, and the opening of the electronic expansion valve set by the valve opening setting unit. FIG. 3 is a flowchart showing the contents of the expansion valve opening degree control process performed by the valve opening degree adjusting means shown in FIG. FIG. 4 is a flowchart showing the contents of the operation state determination control process during pull-down operation. FIG. 5 is a flowchart showing the contents of the operation state determination control process during normal operation. FIG. 6 is a flowchart showing the contents of the valve opening correction control process shown in FIG.

  Hereinafter, preferred embodiments of a cooling device according to the present invention will be described in detail with reference to the accompanying drawings as appropriate.

  FIG. 1 is a conceptual diagram conceptually showing the configuration of a cooling device according to an embodiment of the present invention. The cooling device exemplified here is applied to an open showcase (accommodating device) 11 that displays and sells products stored in the storage 10 in a cooled state, and each of the open showcases 11 has an evaporator 12. In addition, the electronic expansion valve 13 is individually provided, while the open showcase 11 is provided with one condenser 14 and one compressor 15 constituting the refrigerator.

  The electronic expansion valve 13 is for adiabatically expanding the liquid refrigerant discharged from the condenser 14 and supplying it to the evaporator 12. In the present embodiment, overheating defined as the difference between the refrigerant temperature at the outlet of the evaporator 12 (hereinafter also referred to as outlet temperature) and the refrigerant temperature at the inlet of the evaporator 12 (hereinafter also referred to as inlet temperature). Based on the degree, the opening degree is changed, and the one that can adjust the flow rate of the refrigerant passing therethrough is applied. More specifically, the electronic expansion valve 13 expands the opening when the degree of superheat is large, and reduces the opening when the degree of superheat is small.

  The compressor 15 compresses the low-temperature and low-pressure gas refrigerant discharged from the evaporator 12 and supplies it to the condenser 14 as a high-temperature and high-pressure gas refrigerant. In the present embodiment, when a pressure value setting command is given, an inverter compressor that can change the suction pressure according to the pressure value setting command is applied.

  In this cooling device, an evaporator 12 and an electronic expansion valve 13 provided in each open showcase 11 are connected in parallel to the condenser 14 and the compressor 15 to constitute a refrigeration cycle. That is, the high-temperature and high-pressure gas refrigerant discharged from the compressor 15 dissipates heat in the condenser 14 and becomes a high-temperature and high-pressure liquid refrigerant. This high-temperature and high-pressure liquid refrigerant is branched and supplied to the electronic expansion valve 13 of each open showcase 11 and is adiabatically expanded to be supplied to the evaporator 12 as a low-temperature and low-pressure gas-liquid two-phase refrigerant. The low-temperature low-pressure gas-liquid two-phase refrigerant supplied to the evaporator 12 exchanges heat with the internal atmosphere of the storage 10 supplied by the blower fan 16 and absorbs heat to become a low-temperature low-pressure gas refrigerant. Cool down. The low-temperature and low-pressure gas refrigerant that has passed through the evaporator 12 joins outside the open showcase 11 and is sucked into the compressor 15.

  In each open showcase 11, an inlet refrigerant temperature sensor 20 and an outlet refrigerant temperature sensor 21 are provided in the refrigerant supply pipe 17 connected to the inlet and outlet of the evaporator 12, respectively. Further, although not shown in the figure, an internal temperature sensor is provided inside the storage 10. The inlet refrigerant temperature sensor 20 and the outlet refrigerant temperature sensor 21 detect the temperature of the refrigerant passing through the respective refrigerant supply pipes 17. The internal temperature sensor detects the internal temperature of the container 10. In the present embodiment, the internal temperature sensor is disposed in the vicinity of a cold air outlet (not shown) opened at the upper front side of the storage 10, and the temperature of the air blown from the cold air outlet is stored in the storage. What is detected as an internal temperature of 10 is applied.

  In addition, a lighting device 22 is disposed inside the storage 10 of each open showcase 11. The lighting device 22 is a device that illuminates the interior of the storage 10 by turning on. The lighting device 22 is related to the opening and closing of the front opening by the night cover NC that opens and closes the front opening of the storage 10, and more specifically, when the lighting device 22 is turned off, While the front opening is closed by the cover NC, when the lighting device 22 is turned on, the front opening is opened by the night cover NC.

  The cooling operation cycle by such a cooling device includes a pull-down operation (rapid cooling operation), a normal operation, and a defrosting operation.

  The pull-down operation is an operation for rapidly cooling the internal temperature of the storage 10 that has been raised by the defrosting operation to a set temperature. The normal operation is an operation for maintaining the internal temperature of the storage 10 within the target temperature range of the normal operation after the internal temperature of the storage 10 reaches the set temperature by the pull-down operation. The defrosting operation is performed by stopping the supply of the refrigerant to the evaporator 12 with the valve opening being zero, that is, fully closed, and driving a heater (not shown) disposed in the vicinity of the evaporator 12. In this operation, frost attached to the evaporator 12 is removed. In addition, this defrosting operation is forcedly performed from the normal operation to the defrosting operation every time a fixed time elapses (for example, every 6 hours, such as 3 o'clock, 9 o'clock, 15 o'clock, 21 o'clock). It is set so that it can be switched to, and after a predetermined time elapses or after the temperature in the vicinity of the evaporator 12 reaches a predetermined temperature.

  The cooling device includes a valve opening degree adjusting means 30 as its control system. As is clear from FIG. 1, in the present embodiment, each open showcase 11 is provided with individual valve opening degree adjusting means 30.

  The valve opening degree adjusting means 30 adjusts the opening degree of the electronic expansion valve 13 based on the refrigerant temperatures detected by the inlet refrigerant temperature sensor 20 and the outlet refrigerant temperature sensor 21. The setting storage unit 31 calculates the superheat degree. Unit (superheat degree calculation means) 32, illumination control part (illumination control means) 33, state determination part 34, and valve opening setting part (control means) 35.

  The setting storage unit 31 presets and stores a target superheat degree value of the refrigerant in the evaporator 12 and a set temperature value that is a reference for termination of the pull-down operation. In the present embodiment, the upper limit value (for example, 5 ° C.) and the lower limit value (for example, 2 ° C.) are respectively set as the superheat degree target value.

  The superheat degree calculation unit 32 subtracts the refrigerant temperature detected by the inlet refrigerant temperature sensor 20 (hereinafter also referred to as inlet temperature) from the outlet temperature detected by the outlet refrigerant temperature sensor 21 to obtain the degree of superheat in the evaporator 12. Is to be calculated.

  The illumination control unit 33 controls lighting of the illumination device 22. More specifically, the lighting device 22 is turned on when a predetermined lighting time is reached, and the lighting device 22 is turned off when a predetermined lighting time is reached.

  The state determination unit 34 compares the superheat degree calculated by the superheat degree calculation unit 32 with the superheat degree target value stored in the setting storage unit 31 during the pull-down operation or the normal operation, and performs an open showcase. 11 driving states are judged. More specifically, the state determination unit 34 performs a so-called liquid back in which the compressor 15 sucks the liquid refrigerant when the calculated superheat degree is lower than the lower limit value (for example, 2 ° C.) of the superheat degree target value. When the calculated superheat degree exceeds the upper limit value (for example, 5 ° C.) of the superheat degree target value, it is judged that the superheat degree is excessive. In addition, the state determination unit 34 determines that the degree of superheat is appropriate if the calculated degree of superheat is within the range of the superheat degree target value (for example, within the range of 2 ° C. or more and 5 ° C. or less).

  Although it is the timing of the determination of the operating state of the open showcase 11 by the state determination unit 34, it is always performed during normal operation. In pull-down operation, it is always determined whether the calculated superheat is below the lower limit of the superheat target value, but is the calculated superheat within the range of the superheat target value? Whether or not the internal temperature detected by the internal temperature sensor (the temperature of the air blown from the cold air outlet) adds a reference temperature value (for example, 2 ° C.) to the set temperature value stored in the setting storage unit 31. It is performed when the temperature reaches the set temperature (set temperature + 2 ° C .: hereinafter also referred to as determination temperature).

  The valve opening setting unit 35 sets the opening of the electronic expansion valve 13 according to the determination result of the state determination unit 34. More specifically, the valve opening setting unit 35 increases the opening of the electronic expansion valve 13 by a predetermined size (for example, about 10 pulses) when the opening of the electronic expansion valve 13 is increased. In the case of reduction, it is reduced by a predetermined size (for example, about 10 pulses).

  Further, the valve opening setting unit 35 performs correction setting of the opening of the electronic expansion valve 13 according to the control result of the illumination control unit 33 during pull-down operation or normal operation. More specifically, when the lighting device 22 is turned off by a command from the lighting control unit 33, the valve opening setting unit 35 is set in advance to the opening set according to the determination result of the state determination unit 34. Correction setting for reducing the size by a predetermined size is performed. When the lighting device 22 is lit, the valve opening setting unit 35 sets the opening of the electronic expansion valve 13 according to the determination result of the state determination unit 34 without performing the correction setting. Is. FIG. 2 shows an example of the relationship between the degree of superheat in the evaporator 12, the operating state determined by the state determination unit 34, and the opening of the electronic expansion valve 13 set by the valve opening setting unit 35. .

  FIG. 3 is a flowchart showing the contents of the expansion valve opening degree control process performed by the valve opening degree adjusting means 30 shown in FIG. Hereinafter, the operation of the cooling device will be described with reference to FIG.

  In the expansion valve opening control process shown in FIG. 3, the valve opening adjusting means 30 detects the refrigerant temperature through the inlet refrigerant temperature sensor 20 and the outlet refrigerant temperature sensor 21 (step S101), and through the superheat calculator 32. Then, the degree of superheat in the evaporator 12 is calculated by subtracting the inlet temperature from the detected outlet temperature (step S102).

  The valve opening degree adjusting means 30 that has calculated the degree of superheat in the evaporator 12 performs an operation state determination control process through the state determination unit 34 (step S110).

  4 and 5 are flowcharts showing the contents of the driving state determination control process shown in FIG. 3, respectively. FIG. 4 shows the contents of the driving state determination control process during pull-down operation. FIG. 5 shows the normal operation. The content of the driving | running state judgment control process at the time is shown. In FIG. 5, the same processing contents as those in FIG. 4 are given the same numbers.

  As shown in FIG. 4, the valve opening degree adjusting means 30 that has calculated the degree of superheat in the evaporator 12 during the pull-down operation is the lower limit value of the superheat degree target value stored in the setting storage unit 31 (for example, 2 ° C.). ) Is determined (step S111).

  When the calculated degree of superheat is below the lower limit value of the superheat degree target value (step S111: Yes), the valve opening degree adjusting means 30 causes the compressor 15 to suck the liquid refrigerant through the state determination unit 34. That is, it is determined that liquid back will occur (step S112), and then the procedure is returned.

  When the calculated degree of superheat does not fall below the lower limit value of the superheat degree target value (step S111: No), that is, when the calculated degree of superheat is equal to or greater than the lower limit value of the superheat degree target value, the valve opening degree adjusting means 30 The internal temperature of the container 10 is detected through the internal temperature sensor (step S113).

  The valve opening degree adjusting means 30 that has detected the internal temperature reaches the determination temperature (set temperature + 2 ° C.) obtained by adding the predetermined temperature value (for example, 2 ° C.) to the set temperature value stored in the setting storage unit 31. It is determined whether or not it has been done (step S114).

  When the internal temperature has not reached the determination temperature (step S114: No), the valve opening degree adjusting means 30 returns the procedure without performing the processing described later.

  On the other hand, when the internal temperature has reached the determination temperature (step S114: Yes), the valve opening degree adjusting means 30 determines the upper limit value of the superheat degree target value in which the calculated superheat degree is stored in the setting storage unit 31 (for example, 5). It is judged whether it exceeds (degreeC) (step S115).

  When the calculated degree of superheat exceeds the upper limit value of the superheat degree target value (step S115: Yes), the valve opening degree adjusting means 30 determines that the degree of superheat is excessive through the state determination unit 34, and then performs the procedure. Let me return. When the calculated degree of superheat is less than or equal to the upper limit value of the superheat degree target value (step 115: No), that is, when the calculated degree of superheat is greater than or equal to the lower limit value of the superheat degree target value and less than or equal to the upper limit value The means 30 determines that the degree of superheat is appropriate through the state determination unit 34 (step S117), and then returns the procedure.

  Thus, during pull-down operation, when the degree of superheat is calculated, it is determined whether the calculated degree of superheat is below the lower limit of the superheat degree target value, that is, whether liquid back will occur. Only when the internal temperature reaches the judgment temperature (set temperature + 2 ° C), whether or not the calculated superheat exceeds the upper limit of the superheat target or whether the superheat is equal to the superheat target It is determined whether or not it is within the target range, that is, whether or not the degree of superheat is appropriate. According to this, at the time of pull-down operation, it is possible to prevent the occurrence of liquid back and to determine whether or not the degree of superheat is appropriate only when the internal temperature reaches the determination temperature. Therefore, the determination at the time when the internal temperature of the container 10 is cooled and the pull-down operation is stabilized becomes possible, and the reliability of the determination can be improved.

  As shown in FIG. 5, the valve opening degree adjusting means 30 that calculates the degree of superheat in the evaporator 12 during normal operation has a lower limit value (for example, 2 ° C.) of the superheat degree target value stored in the setting storage unit 31. ) Is determined (step S111).

  When the calculated degree of superheat is below the lower limit value of the superheat degree target value (step S111: Yes), the valve opening degree adjusting means 30 causes the compressor 15 to suck the liquid refrigerant through the state determination unit 34. That is, it is determined that liquid back will occur (step S112), and then the procedure is returned.

  When the calculated superheat degree exceeds the upper limit value (for example, 5 ° C.) of the superheat degree target value stored in the setting storage unit 31 (step S111: No, step S118: Yes), the valve opening degree adjusting means 30 is The state determination unit 34 determines that the degree of superheat is excessive, and then returns the procedure.

  When the calculated superheat degree is not less than the lower limit value and not more than the upper limit value of the superheat degree target value (step S111: No, step S118: No), the valve opening degree adjusting means 30 has an appropriate degree of superheat through the state determination unit 34. (Step S120), and then the procedure is returned.

  Thus, during normal operation, regardless of the detection result of the internal temperature, when the degree of superheat is calculated, by constantly comparing whether the calculated degree of superheat is within the range of the superheat degree target value, It is determined whether or not the degree of superheat is appropriate and whether or not liquid back occurs.

  The valve opening degree adjusting means 30 that has performed the operation state determination control process as shown in FIGS. 4 and 5 performs the valve opening degree correction control process as shown in FIG. 3 (step S130).

  FIG. 6 is a flowchart showing the contents of the valve opening correction control process shown in FIG. In the valve opening degree correction control process shown in FIG. 6, when the valve opening degree adjusting means 30 determines that the liquid back is generated in the above-described operation state determination control process (step S131: Yes), the valve opening degree setting is performed. The opening degree of the electronic expansion valve 13 is reduced through the unit 35, that is, set to an opening degree reduced by a predetermined size (step S132).

  When it is determined that the degree of superheat is excessive in the above-described operation state determination control process (step S131: No, step S133: Yes), the valve opening degree adjusting means 30 is connected to the electronic expansion valve 13 through the valve opening degree setting unit 35. The opening is enlarged, that is, set to an opening obtained by adding a predetermined amount (step S134).

  On the other hand, when it is determined that the degree of superheat is appropriate in the operation state determination control process described above (step S131: No, step S133: No), the valve opening degree adjusting means 30 performs electronic expansion through the valve opening degree setting unit 35. Settings are made to maintain the opening of the valve 13 (step S135).

  The valve opening degree adjusting means 30 that has set the opening degree of the electronic expansion valve 13 through the valve opening degree setting unit 35 in this way determines whether or not the lighting control unit 33 has turned off the lighting device 22 (step S136). ).

  When the lighting device 22 is not turned off (step S136: No), that is, when the lighting control unit 33 turns on the lighting device 22, the valve opening degree adjusting means 30 is in step S132, step S134 or step S135. A command signal of the set opening degree is given to the electronic expansion valve 13, and then the procedure is returned. By providing the electronic expansion valve 13 with the command signal of the opening set in step S132, the supply of refrigerant to the evaporator 12 is reduced, and the degree of superheat in the evaporator 12 is increased. Moreover, by supplying the command signal of the opening set in step S134 to the electronic expansion valve 13, the supply of the refrigerant to the evaporator 12 is increased, and the superheat degree is lowered.

  On the other hand, when the lighting device 22 is turned off (Step S136: Yes), the valve opening degree adjusting means 30 is set to the opening degree set in Steps S132, S134, and S135 through the valve opening degree setting unit 35. Correction setting for reducing by a predetermined size is performed (step S137), and then the procedure is returned to complete the valve opening correction control process and the expansion valve opening control process.

  As described above, according to the cooling device according to the embodiment of the present invention, when the valve opening degree setting unit 35 of the valve opening degree adjusting unit 30 is turned off by the lighting control unit 33, the lighting device 22 is turned off. Correction setting for reducing the opening degree of the electronic expansion valve 13 set by comparing the superheat degree calculated by the superheat degree calculation unit 32 with the superheat degree target value stored in the setting storage unit 31 by a predetermined amount. Therefore, even when the lighting device 22 is turned off and the front opening is closed by the night cover NC and the cooling load inside the storage 10 is reduced, the liquid refrigerant is sufficiently evaporated by the evaporator 12. Therefore, there is no possibility that the compressor 15 sucks the liquid refrigerant and causes a so-called liquid back phenomenon. Therefore, the compressor 15 can be used as a liquid refrigerant by adjusting the opening of the electronic expansion valve 13 by predicting the cooling load of the storage 10 according to the lighting state of the lighting device 22 disposed in the storage 10. Can be suppressed.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to this, and various modifications can be made.

  In the embodiment described above, the opening degree of the electronic expansion valve 13 set in steps S132, S134, and S135 depends on the size when the lighting device 22 is turned on and the front opening is opened. However, in the present invention, the opening degree of the electronic expansion valve 13 set in steps S132, S134, and S135 is such that the lighting device 22 is turned off and the front opening is closed by the night cover NC. It does not matter if the size is. In this case, it is not determined whether or not the lighting device 22 is turned off as in step S136, but it is determined whether or not the lighting device 22 is turned on. As a result, when the lighting device 22 is turned on, the control means (valve opening setting unit 35) may perform correction setting for expanding the set opening by a predetermined size. By performing the correction setting as described above, the compressor 15 can be prevented from sucking the liquid refrigerant. And there is no possibility that the superheat degree in the evaporator 12 will become excessive with the increase in the cooling load in the inside of the storage 10, and the fall of the cooling rate of the storage 10 can be suppressed.

  As described above, the cooling device according to the present invention is useful for cooling the open showcase container.

DESCRIPTION OF SYMBOLS 10 Container 11 Open showcase 12 Evaporator 13 Electronic expansion valve 14 Condenser 15 Compressor 20 Inlet part refrigerant | coolant temperature sensor 21 Outlet part refrigerant | coolant temperature sensor 22 Illumination equipment 30 Valve opening degree adjustment means 31 Setting memory | storage part 32 Superheat degree calculation part 33 Illumination control unit 34 State determination unit 35 Valve opening setting unit NC Night cover

Claims (3)

In the cooling device that adjusts the opening of the electronic expansion valve and controls the supply of the refrigerant to the evaporator disposed in the storage device to bring the storage of the storage device into a desired temperature state,
Lighting control means for controlling lighting of lighting equipment disposed in the storage;
And a control unit that performs correction control to reduce the opening of the electronic expansion valve by a predetermined size when the lighting device is turned off by the lighting control unit. . Subtracting the refrigerant inlet temperature at the inlet of the evaporator from the outlet temperature of the refrigerant at the outlet of the evaporator, the superheat degree calculating means for calculating the degree of superheat in the evaporator,
The control means, when performing a pull-down operation for cooling the internal temperature of the storage to a preset temperature after completion of the defrosting operation, at a time point higher than the set temperature by a predetermined reference temperature. If the degree of superheat calculated by the superheat degree calculation means exceeds the predetermined upper limit value of the superheat degree target value, the opening degree of the electronic expansion valve is expanded, while the degree of superheat is calculated by the superheat degree calculation means at the time point 2. The cooling device according to claim 1, wherein control is performed to maintain the opening degree of the electronic expansion valve when the degree of superheat is within a range between a lower limit value and an upper limit value of a superheat target value. .   In the pull-down operation, when the degree of superheat calculated by the superheat degree calculation means is less than a predetermined lower limit value of the superheat degree target value, the control means sucks the liquid refrigerant. The cooling device according to claim 2, wherein the opening degree of the electronic expansion valve is reduced by judging that the electronic expansion valve has been lost.

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