JP2008286474A - Cooling storage and its operation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling storage and its operation method capable of performing the stable cooling operation even when set temperatures of storage compartments are close to each other in the cooling storage where the plurality of storage compartments are cooled by one compressor. <P>SOLUTION: This cooling storage comprises the compressor 20 driven by an invertor motor, a condenser 21, electric expansion valves 26A, 26B, evaporators 16A, 16B, a target temperature setting means 55 for setting target temperatures of the storage compartments, inside temperature sensors 51A, 51B detecting inside temperatures of the storage compartments, a compressor rotation control means 51 generating cooling capacity to keep the storage compartment at its target temperatures by controlling the rotational frequency of the compressor on the basis of the deviation between the target temperature set by the target temperature setting means and the inside temperature detected by the inside temperature sensor, and an electric expansion valve control means distributing the refrigerant from the condenser to each of the evaporators by controlling an opening of each of the plurality of electric expansion valves according to the deviation between the target temperature of each storage compartment and the inside temperature. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a cooling storage that includes a plurality of evaporators and supplies refrigerant from a single compressor to the evaporator, and an operation method thereof.

  As this type of cooling storage, for example, a freezing compartment and a refrigeration compartment are insulated and formed in a heat-insulating storage body, and an evaporator is disposed in each chamber, and each evaporator is provided with a single compressor. One in which a coolant is alternately supplied to cause a cooling action is known. For example, Patent Document 1 can be exemplified.

In this system, the refrigerant is compressed by a compressor and liquefied by a condenser, and this is alternately supplied to a freezer evaporator and a refrigerator refrigerator connected to the outlet side of the three-way valve via a capillary tube, respectively. During the so-called control operation in which the normal cooling operation is performed in a temperature range close to the set temperature, the compressor starts operating when one of the storage chambers reaches the on temperature, and the cooling side When the storage chamber reaches the off temperature, the three-way valve is switched to switch to the cooling mode of the other storage chamber, and the compressor is stopped when the detected temperatures in both chambers are both below the off temperature.
Japanese Utility Model Publication No. 60-188982

  However, regardless of whether the target temperatures of the two chambers are set to greatly different temperature ranges such as the refrigeration temperature range and the refrigeration temperature range as described above, for example, a temperature setting that sets both to the refrigeration temperature range, for example. Then, there was a problem that stable operation could not be performed. For example, when there are two storage rooms, it is assumed that one set temperature is set to 5 ° C. and the other set temperature is set to 3 ° C. The compressor starts when the internal temperature of one storage room exceeds the on-temperature, and one storage room is cooled to the off-temperature (the temperature difference between the off-temperature and the on-temperature usually requires a minimum of 3K). At this point, the three-way valve switches to the cooling mode on the other side. At this time, if the storage chamber on the other side is at an off temperature, the compressor is continuously operated. However, if the set temperatures of both storage chambers are close, the control temperatures of both storage chambers overlap, making it difficult to distinguish and control the fine set temperatures.

  The present invention has been completed based on the above circumstances, and is capable of stably cooling a plurality of storage rooms with a single compressor even when the set temperatures of the respective storage rooms are close. It is an object of the present invention to provide a cooling storage and a method of operating the same that can perform a cooling operation.

  The cooling storage of the present invention includes a compressor driven by an inverter motor, a condenser that releases heat from the refrigerant compressed by the compressor, and a plurality of refrigerant supplies that respectively flow the refrigerant from the condenser through an electric expansion valve. Passages, evaporators provided in the respective refrigerant supply paths, refrigerant circulation passages for bringing the refrigerant evaporated in the respective evaporators together and returning them to the suction side of the compressor, and cold air generated by the respective evaporators A plurality of storage chambers to be cooled, target temperature setting means for setting a target temperature in each of the storage chambers, an internal temperature sensor for detecting the internal temperature of each of the storage chambers, and the target temperature setting means Cooling for maintaining each storage chamber at the target temperature by controlling the number of revolutions of the compressor based on the deviation between the set target temperature and the internal temperature detected by the internal temperature sensor Ability A compressor rotation control means for controlling the opening degree of each of the plurality of electric expansion valves according to each deviation between the target temperature of the storage chamber and the internal temperature, and the refrigerant from the condenser is An electric expansion valve control means for distributing to each of the evaporators is provided.

  According to the above configuration, the electric expansion valve control means controls the opening degree of the electric expansion valve so that the refrigerant is distributed and controlled so as to maintain the target temperature of each storage chamber, and in order to realize this, the compressor rotates. The rotation speed of the compressor is controlled by the control means so as to generate a cooling capacity for maintaining each storage chamber at the target temperature. For this reason, since the cooling capacity can be distributed to each storage room without depending on on / off of the compressor, stable control can be performed even if the set temperature of each storage room is close.

  The compressor rotation control means includes a deviation calculation means for calculating a deviation between the target temperature set in the target temperature setting means and the internal temperature detected by the temperature sensor every predetermined time, and the deviation calculation It is preferable that a rotation speed control means for changing the rotation speed of the inverter motor by comparing the integrated value of the deviation calculated by the means with a predetermined reference value.

  The electric expansion valve control means includes a deviation calculating means for calculating a deviation between the target temperature set in the target temperature setting means and the internal temperature detected by the temperature sensor every predetermined time; The integrated value of the deviation calculated by the deviation calculating means for each storage chamber is compared with a predetermined reference value, and when the integrated value is smaller than the predetermined reference value, the electric expansion valve is closed by a predetermined amount and the integrated It is preferable to provide an electric expansion valve comparison drive means for performing control to open the electric expansion valve by a predetermined amount when the value is larger than a predetermined reference value.

  It is further preferable to provide a superheat degree detecting means for detecting the superheat degree of the refrigerant sucked into the compressor and stop the operation of the compressor when the superheat degree falls below a predetermined value.

  According to the cooling storage of the present invention, a plurality of storage chambers are cooled by a single compressor, and a stable cooling operation can be performed even when the set temperatures of the respective storage chambers are close.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS. In this Embodiment 1, the case where it applies to the horizontal type | mold (table type) refrigerator for business is illustrated, First, FIG. 1 demonstrates the whole structure. Reference numeral 10 denotes a storage body, which is composed of a horizontally long heat insulating box that opens to the front surface, and is supported by legs 11 provided at the four corners of the bottom surface. The interior of the storage body 10 is divided into left and right by a heat-insulating partition wall 12 to be retrofitted, and the left relatively narrow side is the first storage chamber 13A, and the right wide side is the second storage chamber 13B. ing. Although not shown, a swinging heat insulating door is attached to the opening of the front surface of each of the storage chambers 13A and 13B so as to be openable and closable.

  A machine room 14 is provided on the left side as viewed from the front of the storage body 10. A heat-insulating evaporator chamber 15 communicating with the first storage chamber 13A via a duct 15A is formed on the back side of the upper portion in the machine chamber 14, and the first evaporator 16A and the evaporator fan are formed here. 17A and a compressor unit 18 is housed in the lower part of the machine room 14 so as to be able to be taken in and out. An evaporator chamber 19 is formed on the surface of the partition wall 12 on the second storage chamber 13B side by extending a duct 19A, and a second evaporator 16B and an evaporator fan 17B are provided there. Yes.

  The compressor unit 18 includes a variable capacity compressor 20 driven by an inverter drive motor, and a condenser 21 connected to the refrigerant discharge side of the compressor 20 on a base 40, and is installed in a machine room 14. A condenser fan 22 (shown only in FIG. 2) for air-cooling the condenser 21 is also mounted.

  FIG. 2 shows the refrigeration cycle and its control device together. As shown in the figure, the outlet side of the condenser 21 is provided with a branching portion 25 that branches into a plurality of, for example, two flow paths of the first and second refrigerant supply paths 24A and 24B after passing through the dryer 23. ing.

  A first electric expansion valve 26A as a throttling device and the first evaporator 16A are provided in series in the first refrigerant supply path 24A. The second refrigerant supply path 24B is provided with a second electric expansion valve 26B, which is also a throttling device, and the second evaporator 16B in series. A refrigerant circulation passage 30 is provided on the refrigerant outlet side of both the evaporators 16A and 16B. The refrigerant circulation passage 30 is connected in common by a confluence connection point 28 and is connected to the suction side of the compressor 20 via an accumulator 29.

  The compressor 20 and the first and second electric expansion valves 26A, 26B are controlled by a refrigeration cycle control circuit 50. The refrigeration cycle control circuit 50 includes a controller 51 with a built-in CPU, which detects the air temperature in the first storage chamber 13A and the first temperature sensor 51A for detecting the air temperature in the first storage chamber 13A. A signal from the second temperature sensor 51B is provided.

  Each of the evaporators 27A and 27B is provided with first and second evaporator inlet temperature sensors 52A and 52B for detecting the temperature of the refrigerant flowing into the evaporators 27A and 27B, and further downstream of the junction connection point 28. An intake refrigerant temperature sensor 53 for detecting the temperature of the combined refrigerant is provided on the inflow side of the accumulator 29, and signals from these sensors 52A, 52B, 53 are also given to the controller 51 of the refrigeration cycle control circuit 50. It is done.

  On the other hand, the refrigeration cycle control circuit 50 is provided with a target temperature setter 55. The target temperature setter 55 is configured to sequentially output the target temperature in a manner that changes with the passage of time according to the set temperature set by the user as the maintenance temperature of the stored items in the storage chambers 13A and 13B. That is, each target temperature of each of the storage chambers 13A and 13B is output as a temporal change mode that brings the internal temperature to the set temperature (that is, a state in which the target temperature is changed toward the set temperature with time t). There are two types of target temperature change modes (target temperature change curves): a change mode during pull-down cooling operation and a change mode during control operation. The latter performs an operation of cooling a stored product such as food so as to be maintained at a set temperature set by the user (for example, about + 4 ° C. in the temperature range of the refrigerator compartment and about −20 ° C. in the temperature range of the freezer compartment). It is a change mode of the target temperature at the time. The latter is a target temperature for cooling from room temperature (for example, + 15 ° C.), which is considerably higher than the set temperature during control operation, to a temperature range during control operation, such as when the power is turned on for the first time after installing a refrigerator. It is a change aspect of. Each change mode is expressed by a function with the elapsed time t from the start of the operation of the compressor 20 as a variable for each storage chamber 13A, 13B and for each set temperature, and the function is configured by, for example, EPROM or the like. It is stored in the storage means. Of the target temperature change modes during the pull-down cooling operation, for example, a function fF (t) indicating a change mode to the temperature range of the freezer compartment and a function fR (t) indicating a target temperature change mode reaching the temperature range of the refrigerator compartment. ) Can be exemplified by those represented by the graph shown in FIG.

  Further, the refrigeration cycle control circuit 50 includes the target temperature TAa of the first storage chamber 13A set in the target temperature setter 55 and the actual internal temperature of the first storage chamber 13A detected by the temperature sensor 51A. A first temperature deviation ΔTA, which is a difference from TA (TA−TAa), is calculated, and the target temperature TBa of the second storage chamber 13B set in the target temperature setter 55 is detected by the temperature sensor 51B. There is provided temperature deviation calculating means for calculating a second temperature deviation ΔTB which is a difference (TB−TBa) from the actual internal temperature TB of the second storage chamber 13B. The temperature deviation calculating means and the electric expansion valve control means are configured by software executed by the CPU, and the specific control mode is as shown in the flowcharts of FIGS. Next, the operation of this embodiment will be described.

  When the power is turned on and the target temperatures TAa and TBa are set by the target temperature setter 55, the compressor 20 is started and the control flows shown in FIGS. 4 to 6 are executed simultaneously.

<Compressor rotation control routine>
In the compressor rotation control routine shown in FIG. 4, first, the integrated value C is initialized (step S11), and then the target temperature TAa is calculated by a function representing the target temperature curve of the first storage chamber 13A (step S12). Further, the target temperature TBa is calculated by a function representing the target temperature curve of the second storage chamber 13B (step S13). At that time, the deviation (TA−TAa) between the actual internal temperature TA and the target temperature TAa of the first storage chamber 13A given from the first temperature sensor 51A and the second temperature sensor 51B give An integration process (step S14) is performed in which a deviation (TB-TBa) between the actual internal temperature TB of the second storage chamber 13B and the target temperature TBa is calculated and added to the integrated value C. .

  Next, the integrated value C calculated in step S14 is compared with two upper limit reference values L_UP and a lower limit reference value L_DOWN (step S15). If the integrated value C is larger than the upper limit reference value L_UP, the compressor 20 Is increased by a predetermined amount (step S16), and if the integrated value C is smaller than the lower limit reference value L_DOWN, the rotational speed of the compressor 20 is decreased by a predetermined amount (step S17) and the integrated value C is initialized (step S16). S18) and the process returns to step S12. When the integrated value C is between the upper limit reference value L_UP and the lower limit reference value L_DOWN, the process returns to step S12 without changing the rotational speed of the compressor 20.

By repeating this routine, the overall cooling capacity is maintained so that both storage chambers 13A and 13B can follow the target temperature curve.
In addition, when the heat load is small and the cooling capacity becomes excessive even when the compressor is operated at a predetermined minimum rotational speed (the process of reducing the rotational speed of the compressor (step S17) is repeated), the compressor 20 is stopped to prevent overcooling in the cabinet (the flowchart is omitted). Here, in order to prevent the fluctuation of the temperature by minimizing the stop / restart of the compressor 20, even if the assumed heat load is the smallest, the compressor 20 is operated so as not to have excessive capacity if it is operated at the minimum rotation speed. It is preferable to select the capacity of the machine 20.

<Expansion valve opening control routine>
On the other hand, while the overall cooling capacity is secured as described above, the distribution of the cooling capacity for the first and second storage chambers 13A and 13B is determined by the expansion valve opening degree control routine described below. The
FIG. 5 shows an expansion valve opening control routine for the first storage chamber 13A. Here, first, the integrated value D is initialized (step S21), then the target temperature TAa is calculated by a function representing the target temperature curve of the first storage chamber 13A (step S22), and then the temperature sensor at that point in time. A deviation (TA-TAa) between the actual internal temperature TA of the first storage chamber 13A given from 51A and the target temperature TAa is calculated, and this is added to the integrated value D (step S23). .

  Then, the integrated value D calculated in step S23 is compared with the valve opening threshold L_OPEN and the valve closing threshold L_CLOSE (step S24). Here, if the integrated value D is larger than the valve opening threshold L_OPEN, the opening degree of the first electric expansion valve 26A is increased by a predetermined amount (step S25), and the flow rate of the refrigerant flowing through the first evaporator 27A is increased. Thus, the cooling capacity of the first storage chamber 13A is increased. Conversely, if the integrated value D is smaller than the valve closing threshold L_CLOSE, the opening degree of the first electric expansion valve 26A is decreased by a predetermined amount (step S26), and the refrigerant flow rate is decreased to cool the first storage chamber 13B. Decrease ability. When the opening degree of the first electric expansion valve 26A is adjusted as described above, the integrated value D is initialized (step S27), and the process returns to step S22. If the integrated value D is between the above two thresholds, the process returns to step S22 without changing the opening of the first electric expansion valve 26A.

  By repeating this routine, the flow rate of the refrigerant flowing through the first evaporator 27A is adjusted so that the temperature of the first storage chamber 13A follows the target temperature curve.

  Further, the second storage chamber 13B is the same as the case of the first storage chamber 13A described above. That is, the deviation between the actual internal temperature TB of the second storage chamber 13B given from the temperature sensor 51B and the target temperature TBa is integrated, and if the integrated value exceeds a certain value, the second electric expansion valve 26B is added. The opening degree of the second storage chamber 13B is adjusted so that the temperature of the second storage chamber 13B follows the target temperature curve. .

  As a result of adjusting the opening degree of each of the first and second electric expansion valves 26A, 26B, the liquid refrigerant from the condenser 21 has a deviation between the target temperature of each storage chamber 13A, 13B and the internal temperature. Accordingly, the temperature is distributed to the evaporators 16A and 16B, and the internal temperatures of the storage chambers 13A and 13B are respectively maintained at the target temperatures.

<Liquid back prevention control routine>
If the cooling load becomes very large only by combining the above-described controls, for example, when the actual storage room temperature TA, TB cannot follow the target temperature curve during the pull-down cooling operation, the electric expansion valves 26A, 26B are provided. There is a possibility that the valve-opening operation will continue to be performed in a fixed amount and eventually become fully open. Then, the liquid refrigerant returns to the inflow side of the compressor 20 and the compressor 20 may be damaged.

  Therefore, in this embodiment, the following liquid back prevention control routine is also executed simultaneously. That is, the superheat degree SH of the refrigerant at the position of the intake refrigerant temperature sensor 53 is calculated in step S31. Here, the superheat degree SH is a value obtained by subtracting the temperature TEA measured by the first evaporator inlet temperature sensor 52A from the temperature TS measured by the suction refrigerant temperature sensor 53. When the degree of superheat SH becomes equal to or less than a predetermined lower limit L_DOWN (for example, 3K) (step S32), the opening degrees of both the first and second electric expansion valves 26A, 26B are reduced by a predetermined amount (step S33). , S34), the process returns to step S31.

  Since the expansion valve opening control routine described above is executed simultaneously with the liquid back prevention control routine, an instruction to increase the opening of the electric expansion valve 26A or 26B is issued by the expansion valve opening control routine. In the liquid back prevention control routine, there is a possibility that an instruction to narrow the opening degree is issued in competition with this. In this case, the instruction result of the liquid back prevention control routine is prioritized and the opening degree of the electric expansion valves 26A, 26B is narrowed (the flowchart is omitted).

  As described above, according to the present embodiment, the compressor rotation control routine integrates values obtained by adding the deviations of the rotation speed of the compressor 20 from the target temperature curves of the first and second storage chambers 13A and 13B. Each evaporator 27A is adjusted up and down by the value, and the opening of each electric expansion valve 26A, 26B is adjusted by the value obtained by integrating the deviation from each target temperature curve by the expansion valve opening control routine. , 27B, the balance of the refrigerant flow rate is determined, so that even when the set temperatures of the respective storage chambers are close, it is possible to reliably cool so as to reach the set temperature.

  In addition, while controlling the opening degree of such an electric expansion valve, the liquid back prevention control routine detects the degree of refrigerant superheat so that it does not drop below a certain level. Breakage can be reliably prevented.

<Embodiment 2>
7 and 8 show Embodiment 2 of the present invention, and show an example in which the present invention is applied to a horizontal refrigerator that also has two storage rooms. In the second embodiment, the configuration of the refrigeration cycle 40 is the same as that of the first embodiment, as shown in FIG. The configuration of the refrigeration cycle control device 50 is different as follows. In the first embodiment, the suction refrigerant temperature sensor 53 is provided on the inflow side of the accumulator 29 in order to detect the degree of superheat of the refrigerant returning to the compressor 20, but in the second embodiment, the first and second evaporations are performed. Evaporator outlet temperature sensors 56A and 56B are provided on the outlet sides of the evaporators 27A and 27B, respectively.

  The control routine of the compressor 20 and the two electric expansion valves 26A and 26B is the same as that of the first embodiment described with reference to FIGS. On the other hand, the liquid back prevention control routine is as shown in FIG. In steps S41 and S42, the superheat degrees SHA and SHB of the refrigerant at the positions of the evaporator outlet temperature sensors 56A and 56B are calculated. Each degree of superheat is obtained by subtracting the detected temperature at the position of each evaporator inlet temperature sensor 52A, 52B from the detected temperature at the position of each evaporator outlet temperature sensor 56A, 56B. When the degree of superheat SHA, SHB becomes a predetermined lower limit L_DOWN (for example, 3K) or less (steps S43, S44), the opening degree of both the first and second electric expansion valves 26A, 26B is set to a predetermined amount. Decrease the size (steps S45 and S46) and return to step S41.

  Since the expansion valve opening control routine described above is executed simultaneously with the liquid back prevention control routine, an instruction to increase the opening of the electric expansion valve 26A or 26B is issued by the expansion valve opening control routine. In the liquid back prevention control routine, there is a possibility that an instruction to narrow the opening degree is issued in competition with this. In this case, the instruction result of the liquid back prevention control routine is prioritized and the opening degree of the electric expansion valves 26A, 26B is narrowed (the flowchart is omitted).

  As described above, according to the present embodiment, the compressor rotation control routine integrates values obtained by adding the deviations of the rotation speed of the compressor 20 from the target temperature curves of the first and second storage chambers 13A and 13B. Each evaporator 27A is adjusted up and down by the value, and the opening of each electric expansion valve 26A, 26B is adjusted by the value obtained by integrating the deviation from each target temperature curve by the expansion valve opening control routine. , 27B, the balance of the refrigerant flow rate is determined, so that even when the set temperatures of the respective storage chambers are close, it is possible to reliably cool so as to reach the set temperature.

  In addition, while controlling the opening degree of such an electric expansion valve, the liquid back prevention control routine detects the degree of refrigerant superheat so that it does not drop below a certain level. Breakage can be reliably prevented.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention.

  (1) In each of the above embodiments, the deviation between the target temperature and the internal temperature is calculated and integrated every predetermined time, and when the integrated value exceeds a predetermined reference value, the rotational speed of the compressor is immediately set. However, other conditions may be taken into account when determining the rotational speed of the compressor.

  (2) In each of the above-described embodiments, the target temperature setting unit stores a function that represents a temporal change mode of the target temperature in the storage unit, reads the function, and calculates the target temperature as time elapses. However, the present invention is not limited to this. For example, a reference table in which the temporal change mode of the target temperature is compared with the temperature and the elapsed time is prepared in advance, and the reference table is stored in the storage unit. In response to this signal, the target temperature in the storage means may be read out by the table reading means as time passes.

  (3) In each of the above embodiments, a refrigerator having two storage rooms has been described. However, even when three or more storage rooms are provided, the refrigerator can be similarly configured, and the temperature range of each storage room Can be determined independently and independently.

  (4) In each of the above embodiments, the case where the same temperature range in which the two storage chambers 13A and 13B are both in the refrigeration temperature range is set as the target temperature has been described. The target temperature may be set in different temperature ranges where there is a large temperature difference, such as the temperature range and the freezing temperature range.

Sectional drawing of the cooling storehouse which shows Embodiment 1 of this invention Refrigeration cycle configuration diagram of Embodiment 1 The graph which shows the example of the time-dependent change aspect of the target temperature in Embodiment 1. The flowchart which shows the control procedure of the compressor rotation control routine in Embodiment 1. The flowchart which shows the control procedure of the expansion valve solution degree control routine in Embodiment 1. 6 is a flowchart showing a control procedure of a liquid back prevention control routine in the first embodiment. Refrigeration cycle configuration diagram of Embodiment 2 7 is a flowchart showing a control procedure of a liquid back prevention control routine in the second embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Thermal insulation storage 13A ... 1st storage chamber 13B ... 2nd storage chamber 16A ... 1st evaporator 16B ... 2nd evaporator 20 ... Compressor 24A ... 1st refrigerant | coolant supply path 24B ... 2nd refrigerant | coolant Supply path 26A ... 1st electric expansion valve 26B ... 2nd electric expansion valve 30 ... Refrigerant ring flow path 51A, 51B ... Inside temperature sensor 52A, 52B ... Evaporator inlet temperature sensor 55 ... Target temperature setting means 50 ... Refrigeration cycle Control circuit (compressor rotation control means, electric expansion valve control means, deviation calculation means, electric expansion valve comparison drive means, superheat degree detection means, storage means)

Claims (10)

A compressor driven by an inverter motor; a condenser that dissipates heat from the refrigerant compressed by the compressor; a plurality of refrigerant supply passages through which the refrigerant from the condenser flows through an electric expansion valve; An evaporator provided in a passage, a refrigerant circulation passage for condensing refrigerant evaporated in each evaporator and returning the refrigerant to the suction side of the compressor, and a plurality of storage chambers cooled by cold air generated by each evaporator Target temperature setting means for setting a target temperature in each of the storage chambers, an internal temperature sensor for detecting the internal temperature of each of the storage chambers, and the target temperature set in the target temperature setting means Compressor rotation that produces cooling capacity for maintaining each storage chamber at the target temperature by controlling the rotation speed of the compressor based on the deviation from the internal temperature detected by the internal temperature sensor control The refrigerant from the condenser is supplied to each evaporator by controlling the opening of each of the plurality of electric expansion valves according to the stage and the deviation between the target temperature and the internal temperature of each storage chamber Cooling storage provided with electric expansion valve control means for distributing. The compressor rotation control means includes a deviation calculating means for calculating a deviation between the target temperature set in the target temperature setting means at every predetermined time and the internal temperature detected by the temperature sensor, and the deviation calculating means. The cooling storage according to claim 1, further comprising: a rotation speed control unit that changes the rotation speed of the inverter motor by comparing the integrated value of the deviation calculated by the above with a predetermined reference value. The electric expansion valve control means includes a deviation calculating means for calculating a deviation between the target temperature set in the target temperature setting means at every predetermined time and the internal temperature detected by the temperature sensor; Every time the integrated value calculated by the deviation calculating means is compared with a predetermined reference value and the integrated value is smaller than the predetermined reference value, the electric expansion valve is closed by a predetermined amount and the integrated value is predetermined. The cooling storage according to claim 1 or 2, further comprising: an electric expansion valve comparison / drive means for performing control to open the electric expansion valve by a predetermined amount when the electric expansion valve is larger than a reference value. The superheat degree detection means for detecting the superheat degree of the refrigerant sucked into the compressor is provided, and the operation of the compressor is stopped when the superheat degree falls below a predetermined value. The cooling storage according to claim 1. The superheat degree detection means includes an evaporator inlet temperature sensor that detects a temperature of a refrigerant flowing into any one of the plurality of evaporators, and a downstream of a refrigerant confluence in the refrigerant circulation passage. The cooling storage according to any one of claims 1 to 4, wherein the refrigerant is provided with an intake refrigerant temperature sensor and detects a degree of superheat of the refrigerant based on a temperature difference detected by the two temperature sensors. . The superheat degree detection means includes an evaporator inlet temperature sensor provided on the refrigerant inlet side of each of the plurality of evaporators, and an evaporator outlet temperature sensor provided on the refrigerant outlet side of each of the evaporators. 5. The refrigerant superheat degree is detected based on the fact that the temperature difference detected by the two temperature sensors exceeds a predetermined reference value for any one of the chambers. 6. The cooling storage according to one item. The cooling storage according to any one of claims 1 to 6, wherein the target temperature setting means is configured to sequentially output different target temperatures as time passes. The target temperature setting means is a storage means for storing a function representing a temporal change mode of the target temperature, and a target temperature calculation for reading the function stored in the storage means and calculating the target temperature as time passes. The cooling storage according to claim 7, comprising means. The target temperature setting means stores storage means as a reference table in which the temporal change mode of the target temperature is contrasted between temperature and elapsed time, and table reading means for reading out the target temperature in the storage means as time elapses The cooling storage of Claim 7 provided with these. The refrigerant is compressed by a variable capacity compressor and radiated by a condenser, and is divided into a plurality of refrigerant supply passages through electric expansion valves, respectively, and a cooling action is generated by an evaporator provided in each refrigerant supply passage. In the cooling storage having a refrigeration cycle in which the refrigerant is combined and returned to the suction side of the compressor, the opening degree of each electric expansion valve is maintained so that the target temperature of each storage chamber is maintained. The compressor is operated to generate a cooling capacity sufficient to maintain the target temperature of both storage chambers, and the superheat of the liquid refrigerant flowing out of the evaporator generates a liquid back. A cooling storage operation method, wherein the compressor is stopped when the pressure drops to a certain extent.

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