Degradation diagnosis system of cooling device

Abstract

To provide a degradation diagnosis system capable of accurately detecting degradation of a cooling device without being affected by a disturbance.SOLUTION: When degradation diagnosis starting time comes, a temperature analysis part 23 first acquires an internal temperature T detected by an internal temperature sensor 11 within a predetermined period and a setting temperature T0 associated with the internal temperature from a temperature data part 27, and calculates a sum total of the temperature difference TD between the corresponding internal temperature T and setting temperature T0 as a temperature difference sum total value ΣTD. Then a comparison determination part 24 acquires power consumption P of a condensing unit 2 from a power meter 30, reads out normal power consumption PN corresponding to the temperature difference sum total value ΣTD calculated by the temperature analysis part 23 from an analysis data part 31, and determines an extent of the cooling device degradation on the basis of the comparison between the acquired power consumption P and the read-out normal power consumption PN.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a deterioration diagnosis system for a cooling device such as a refrigerator or a refrigerated showcase. [Background technology]

[0002] When a cooling device such as a refrigerator or refrigerated showcase stops due to a malfunction, the freshness of the food or other refrigerated items stored therein decreases, and in the worst case, the items spoil. To prevent this, it is desirable to regularly diagnose the degree of deterioration of the cooling device and take appropriate measures, such as repairing or replacing the cooling device, before it completely fails. Various methods for diagnosing the degree of deterioration of a cooling device are known. For example, Patent Document 1 performs a diagnosis based on the fact that as the cooling performance of a refrigerator deteriorates, the compressor's operating time increases and the refrigerator's power consumption increases. Specifically, a portion of a late-night period when there are fewer disturbances such as door openings is set as the measurement time, the refrigerator's power consumption during this period is measured, the total compressor operating time is estimated based on the measured power consumption, and the ratio of this total operating time to the measured time is calculated. The calculated ratio is then compared with the ratio recorded when the refrigerator was normal (when it was new), and the greater the discrepancy between the two, the more severe the deterioration of the refrigerator's cooling performance is determined to be. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-117752 Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, in Patent Document 1, the degree of deterioration of a refrigerator is diagnosed based on the amount of power consumed by the refrigerator during late-night hours when there are fewer disturbances. However, in stores such as supermarkets that are closed late at night, the operation of the cooling equipment (especially the refrigerated showcases) may be suppressed or stopped during the closed hours from the perspective of energy conservation. In other words, these stores only operate their cooling equipment during business hours when there are many disturbances, such as customers visiting the store, and it is therefore inappropriate to apply the method of Patent Document 1, which was designed on the assumption that there are times when there are fewer disturbances, to these cooling equipment. Because the amount of power consumed by a cooling equipment fluctuates due to disturbances, even if the amount of power consumed is measured during business hours when there are many disturbances, it is difficult to accurately diagnose the degree of deterioration of the cooling equipment based solely on that amount of power consumption.

[0005] An object of the present invention is to provide a deterioration diagnosis system that can accurately detect deterioration of a cooling device without being affected by external disturbances. [Means for solving the problem]

[0006] The present invention is directed to a deterioration diagnosis system for a cooling device having an evaporator 12 disposed in a compartment 6 for storing an object to be cooled, and a condensing unit 2 for sending refrigerant to the evaporator 12. This system comprises an interior temperature sensor 11 for detecting the temperature of the interior 6, a wattmeter 30 for measuring the amount of power consumed P by the condensing unit 2 within a predetermined period, a temperature data section 27 for correlating and recording the interior temperature T detected by the interior temperature sensor 11 at each predetermined time with the set temperature T0 of the interior 6 at that time, a diagnostic data section 31 for storing a normal amount of power PN which is a normal value for the amount of power consumed P, and a deterioration diagnosis start time and a diagnostic data section 32 for storing the interior temperature T detected within the predetermined period ending at that time and the corresponding set temperature T0. The temperature analysis unit 23 acquires the set temperature T0 and the corresponding internal temperature T from the temperature data unit 27, and calculates the sum of the temperature difference TD between the corresponding internal temperature T and the set temperature T0 as a temperature difference sum value ΣTD, and the comparison and determination unit 24 acquires the power consumption P within the specified period ending at the start time from the power meter 30, reads out the normal power consumption PN corresponding to the temperature difference sum value ΣTD calculated by the temperature analysis unit 23 from the diagnostic data unit 31, and determines the degree of deterioration of the cooling device based on a comparison between the acquired power consumption P and the read normal power consumption PN.

[0007] The comparison / determination unit 24 determines that the cooling device has deteriorated when the power consumption amount P acquired from the power meter 30 exceeds or falls below an allowable range set based on the normal power consumption amount PN.

[0008] When the power consumption amount P falls below the allowable range, the comparison and determination unit 24 estimates that the type of deterioration of the cooling device is a refrigerant leak or poor air circulation inside the refrigerator 6.

[0009] When the power consumption P falls below the allowable range, the comparison and determination unit 24 refers to the comparison results between the power consumption P and the normal power consumption PN from that point back to a specified reference point, and if the power consumption P has exceeded the normal power consumption PN since the reference point, it estimates that there is a refrigerant leak in the cooling device, and if the power consumption P has always been below the normal power consumption PN since the reference point, it estimates that there is poor air circulation inside the storage unit 6. [Effects of the Invention]

[0010] In the cooling device degradation diagnosis system according to the present invention, the internal temperature T at each predetermined time interval and the set temperature T0 at that time are associated and recorded in the temperature data section 27, and the normal power amount PN, which is the normal value for the power consumption P of the condensing unit 2, is pre-stored in the diagnostic data section 31. When the degradation diagnosis start time arrives, the sum of the temperature difference TD between the internal temperature T and the set temperature T0 within a predetermined period ending at that time is calculated as the total temperature difference value ΣTD, the normal power amount PN corresponding to the calculated total temperature difference value ΣTD is read from the diagnostic data section 31, and the degree of degradation of the cooling device is diagnosed based on a comparison between the actual power consumption P and the read normal power amount PN.

[0011] The temperature difference sum value ΣTD used in the present invention is the sum of the temperature difference TD between the internal temperature T and the set temperature T0, as described above, and it can be said that the smaller this temperature difference sum value ΣTD is, the closer the internal temperature T has been maintained to the set temperature T0 over a specified period of time. Generally, the larger the temperature difference TD between the internal temperature T and the set temperature T0, the higher the output and operation rate of the condensing unit 2 are controlled, and the greater its power consumption P. Therefore, the larger the temperature difference sum value ΣTD is, the higher the normal power consumption PN of the condensing unit 2 is set to be.

[0012] In the present invention, when the power consumption P of the condensing unit 2 becomes relatively high due to a disturbance, such as an increase in the internal temperature T caused by the intrusion of high-temperature outside air, the sum of the temperature difference TD between the internal temperature T and the set temperature T0, i.e., the total temperature difference value ΣTD, increases. Accordingly, the normal power consumption PN also increases. Therefore, the power consumption P does not deviate significantly from the normal power consumption PN, and the cooling device is correctly diagnosed as having no (small) deterioration. On the other hand, when the power consumption P becomes relatively high despite a small total temperature difference value ΣTD in an environment with few disturbances, the normal power consumption PN becomes smaller than in the previous case. Therefore, the power consumption P deviates significantly from the normal power consumption PN, and the cooling device is correctly diagnosed as having deterioration. In other words, according to the present invention, an increase in the power consumption P due to disturbances surrounding the cooling device can be excluded from the indication of deterioration of the cooling device, and only other fluctuations in the power consumption P can be considered as indications of deterioration. This allows accurate detection of deterioration of the cooling device without being affected by disturbances.

[0013] As described in Patent Document 1, deterioration of a cooling device often leads to an increase in power consumption, but depending on the type of deterioration of the cooling device, it may also lead to a decrease in power consumption. If, as in the present invention, it is determined that the cooling device has deteriorated not only when power consumption P exceeds the allowable range but also when it falls below this range, a wider range of deterioration of the cooling device can be detected at an early stage.

[0014] When the power consumption amount P falls below the allowable range, the comparison / determination unit 24 estimates that the type of deterioration in the cooling device is a refrigerant leak or poor air circulation inside the storage unit 6. In this way, if the type of deterioration can be estimated before dispatching a worker to repair the cooling device, the necessary tools and parts can be prepared in advance for the worker, and the type of deterioration in the cooling device can be identified in a short time at the work site.

[0015] If the amount of refrigerant leaks from the cooling system and decreases, the amount of heat absorbed by the evaporator 12 from the air inside the refrigerator decreases, making it difficult to lower the refrigerator temperature T. In particular, at the start of cooling when the refrigerator temperature T significantly exceeds the set temperature T0, the temperature difference TD between the refrigerator temperature T and the set temperature T0 does not decrease easily, and as a result, the compressor 16 of the condensing unit 2 is maintained at high speed, making it more likely that the power consumption P will exceed the normal power consumption PN. However, once the refrigerator interior 6 has cooled to near the set temperature T0, the refrigerant pressure is lower than normal due to the decrease in the amount of refrigerant, so the compressor 16 is maintained at low speed, making it more likely that the power consumption P will fall below the normal power consumption PN. In other words, refrigerant leakage can cause both an increase and a decrease in the power consumption P.

[0016] On the other hand, when poor air circulation inside the refrigerator occurs, cold air tends to stagnate around the evaporator 12, making the refrigerant in the evaporator 12 less likely to be overheated than normal, and the pressure of the refrigerant returning to the condensing unit 2 becomes lower than normal. If the compressor 16 is maintained at a low rotation speed due to this low pressure, the power consumption P tends to fall below the normal power consumption PN. In other words, poor air circulation inside the refrigerator tends to reduce the power consumption P, but it rarely increases it.

[0017] Considering the above, if the power consumption P falls below the allowable range due to a refrigerant leak, it is likely that the power consumption P previously exceeded the normal power consumption PN. If the cause is poor air circulation inside the refrigerator, it is likely that the power consumption P has remained below the normal power consumption PN for some time. Therefore, in this invention, when the power consumption P falls below the allowable range, the system compares the power consumption P and the normal power consumption PN from that point forward up to a specified reference point. If the power consumption P has exceeded the normal power consumption PN since the reference point, it is assumed that the refrigerant in the refrigerator is leaking. If the power consumption P has consistently been below the normal power consumption PN since the reference point, it is assumed that poor air circulation inside the refrigerator is occurring. This allows for a more accurate estimation of the type of deterioration in the refrigerator, thereby providing more appropriate support to workers involved in repairing the refrigerator. [Brief explanation of the drawings]

[0018] [Figure 1] 1 is a block diagram of a control system including a cooling device deterioration diagnosis system according to an embodiment of the present invention. [Figure 2] FIG. 2 is a schematic diagram of a cooling device. [Figure 3] 10 is a graph showing the relationship between the sum of temperature differences and the normal amount of power. DETAILED DESCRIPTION OF THE INVENTION

[0019] (Embodiment) Figures 1 to 3 show an embodiment of a cooling device deterioration diagnosis system according to the present invention. As shown in Figure 2, the cooling device comprises a refrigerated showcase 1 installed inside a store such as a supermarket, and a condensing unit 2 installed outside the store, with the two 1 and 2 connected by refrigerant piping. Note that Figure 2 shows a one-to-one relationship between the refrigerated showcase 1 and the condensing unit 2, but in reality, multiple refrigerated showcases 1 are connected in parallel to one condensing unit 2.

[0020] Refrigerated showcase 1 comprises a case body 5 formed of insulating walls, and an inner case 9 that divides the interior 6 surrounded by the case body 5 into a display room 7 and an air duct 8. Display room 7, which is open at the front, is equipped with multiple upper and lower display shelves 10 on which fresh produce and other foods are displayed, and an interior temperature sensor 11 that detects the temperature of interior 6 (display room 7), i.e., interior temperature T. Air duct 8 is equipped with an evaporator 12 through which a refrigerant that is lower in temperature than the interior temperature T flows, and a circulation fan 13 that circulates air cooled around evaporator 12 throughout interior 6.

[0021] The condensing unit 2 includes a variable speed compressor 16 and a condenser 17 that air-cools the refrigerant compressed by the compressor 16, and is connected to the evaporator 12 of the refrigerated showcase 1 via a refrigerant piping. Specifically, the outlet of the condenser 17 is connected to the inlet of the evaporator 12 via an expansion valve 18 provided for each refrigerated showcase 1, and the outlet of the evaporator 12 is connected to the suction pipe of the compressor 16. The gaseous refrigerant compressed by the compressor 16 is cooled and condensed in the condenser 17, then decompressed by the expansion valve 18 before reaching the evaporator 12, where it vaporizes and cools the surrounding air before returning to the compressor 16. A pressure sensor 19 is provided in the refrigerant piping between the evaporator 12 and the compressor 16 to detect its internal pressure, i.e., the suction pressure of the compressor 16. The rotation speed of the compressor 16 is controlled (inverter controlled) based on the detected value PL of the pressure sensor 19, more specifically, based on the difference between the detected value PL of the suction pressure and its target value PLo. For example, if the detected value PL of the pressure sensor 19 becomes higher than the target value PLo, the rotation speed of the compressor 16 is increased to increase the amount of refrigerant drawn in, thereby lowering the detected value PL and bringing it closer to the target value PLo.

[0022] As shown in FIG. 1, the control system of the cooling device includes a cooling control unit 22 that cools the interior 6 of the refrigerated showcase 1, a temperature analysis unit 23 that diagnoses deterioration of the cooling device, and a comparison / determination unit 24. The cooling control unit 22 controls the opening and closing of the expansion valve 18 (or controls the opening degree if the expansion valve 18 is an electronic expansion valve) to maintain the interior temperature T detected by the interior temperature sensor 11 at the set temperature T0 of the interior 6 set by the temperature setting unit 26. Specifically, when the interior temperature T rises to an upper limit temperature derived from the set temperature T0 (e.g., T0 + 1°C), the expansion valve 18 opens to send refrigerant from the condensing unit 2 to the evaporator 12. When the interior temperature T falls to a lower limit temperature derived from the set temperature T0 (e.g., T0 - 1°C), the expansion valve 18 closes to shut off the refrigerant. The cooling control unit 22 also records the interior temperature T at predetermined intervals (e.g., 5 minutes) in the temperature data unit 27 in association with the set temperature T0 of the interior 6 at that time.

[0023] When the start time of the deterioration diagnosis arrives, the temperature analysis unit 23 acquires the inside temperature T detected within a predetermined period (for example, one hour) ending at that time and the corresponding set temperature T0 from the temperature data unit 27. Then, the temperature analysis unit 23 calculates the sum of the temperature difference TD (TD = T - T0) between the corresponding inside temperature T and the set temperature T0 as a temperature difference sum value ΣTD and transmits this to the comparison / determination unit 24. It can be said that the smaller this temperature difference sum value ΣTD is, the closer the inside temperature T has been maintained to the set temperature T0 over the predetermined period.

[0024] The condensing unit 2 is equipped with a wattmeter 30 that measures the amount of power consumed P within a predetermined period. The length of this predetermined period corresponds to the length of the predetermined period over which the temperature analysis unit 23 tallies the temperature difference TD. The comparison / determination unit 24 compares the amount of power consumed P output by the wattmeter 30 with the normal amount of power consumed PN, which is its normal value, to determine the degree of deterioration of the cooling device. The normal amount of power consumed PN is associated with the sum of the temperature differences TD, i.e., the total temperature difference value ΣTD, and is pre-stored in the diagnostic data unit 31. Generally, the greater the temperature difference TD between the internal temperature T and the set temperature T0, the higher the rotation speed of the compressor 16 is controlled, resulting in a higher amount of power consumed P by the condensing unit 2. Therefore, as shown in the graph of FIG. 3, the normal amount of power consumed PN is set higher as the total temperature difference value ΣTD increases.

[0025] The comparison / determination unit 24 reads out the normal power amount PN corresponding to the temperature difference sum value ΣTD calculated by the temperature analysis unit 23 from the diagnostic data unit 31, and compares the power consumption amount P obtained from the power meter 30 with the normal power amount PN. If the difference between the actual power consumption amount P and the normal power amount PN is within an allowable range, it is determined that the cooling device is not degraded or is small, and if the difference exceeds the allowable range, it is determined that the cooling device is degraded.

[0026] Specifically, an upper power consumption limit PU (PU = PN + α) obtained by adding a tolerance α to the normal power consumption PN and a lower power consumption limit PL (PL = PN - α) obtained by subtracting the tolerance α from the normal power consumption PN were set. This tolerance α may be a constant or a variable that varies according to the normal power consumption PN or the like. And if the power consumption P is greater than or equal to the lower power consumption limit PL and less than or equal to the upper power consumption limit PU (PL ≤ P ≤ PU), it is determined that there is no or little deterioration of the cooling device. If the power consumption P exceeds the upper power consumption limit PU (P > PU) or is less than the lower power consumption limit PL (P < PL), it is determined that some abnormality has occurred in the cooling device, that is, it is deteriorated. When the comparison determination unit 24 determines that the cooling device is deteriorated, it activates the notification means 34 that notifies this fact.

[0027] As one of the abnormalities of the cooling device that causes an abnormal change in the power consumption P, refrigerant leakage due to deterioration of the refrigerant piping or the like can be cited. When the refrigerant leaks and its amount decreases, the amount of heat absorbed from the air in the refrigerator compartment in the evaporator 12 decreases, and it becomes difficult for the temperature T in the refrigerator compartment to drop. In particular, at the cooling start stage where the temperature T in the refrigerator compartment significantly exceeds the set temperature T0, the temperature difference TD between the temperature T in the refrigerator compartment and the set temperature T0 does not easily shrink. In response to this, the refrigerated showcase 1 may give an instruction to lower the target value PLo of the suction pressure of the compressor 16 of the condensing unit 2 in order to lower its own temperature T in the refrigerator compartment. As described above, the rotation speed of the compressor 16 is controlled based on the difference between the detected value PL of the pressure sensor 19 and the target value PLo. When the target value PLo decreases, the state where the detected value PL exceeds the target value PLo continues, and the compressor 16 is maintained at a high rotation speed, so the power consumption P is likely to exceed the upper power consumption limit PU.

[0028] However, when the interior 6 of the refrigerated showcase 1 cools to near the set temperature T0, the temperature difference TD between the interior temperature T and the set temperature T0 decreases, and the target value PLo of the pressure sensor 19 of the condensing unit 2 returns to its original value (increases). Because the refrigerant pressure is lower than normal due to the decrease in the amount of refrigerant, the detected value PL of the pressure sensor 19 falls below the target value PLo. If the detected value PL remains below the target value PLo, the compressor 16 is maintained at a low rotation speed, making it more likely that the power consumption P will fall below the lower limit power PL. As described above, a refrigerant leak can cause both an increase and a decrease in the power consumption P. However, as described above, the comparison / determination unit 24 determines that the cooling device is degraded not only when the power consumption P exceeds the upper limit power PU but also when it is below the lower limit power PL. Therefore, it is possible to correctly detect a cooling device degradation, such as a refrigerant leak, regardless of whether the power consumption P fluctuates upward or downward.

[0029] Another abnormality that can cause a change in the power consumption P is the stopping of the circulation fan 13. When the circulation fan 13 stops due to a malfunction of the fan motor or the like, the air inside the refrigerator 6 stops circulating, reducing the efficiency of heat exchange between the refrigerant and the air in the evaporator 12, making it more difficult for the temperature T inside the refrigerator to drop than normal. On the other hand, cold air tends to stagnate around the evaporator 12, making the refrigerant inside the evaporator 12 less likely to be overheated than normal, and therefore the pressure of the refrigerant returning to the condensing unit 2 becomes lower than normal. When this pressure drops, the compressor 16 is maintained at a low rotation speed, making it more likely that the power consumption P will fall below the lower limit power consumption PL.

[0030] As described above, when the power consumption P falls below the lower limit power PL, a refrigerant leak or the stoppage of the circulation fan 13 can be suspected. To distinguish between the two, past degradation diagnosis results (comparison results between the power consumption P and the normal power PN) can be referenced. Specifically, the comparison results between the power consumption P and the normal power PN are referenced from the time when the power consumption P fell below the lower limit power PL up to a predetermined reference point. If the power consumption P has exceeded the normal power PN since the reference point, it is assumed that there is a refrigerant leak in the cooling system. If the power consumption P has always been below the normal power PN since the reference point, it is assumed that there is poor air circulation in the refrigerator compartment 6. If the comparison / determination unit 24 successfully estimates the type of degradation in the cooling system, it activates the notification means 34, which notifies the user of the type.

[0031] As described above, in the cooling device degradation diagnosis system according to this embodiment, the internal temperature T at each predetermined time period and the set temperature T0 at that time are associated and recorded in the temperature data section 27, and the normal power amount PN, which is the normal value for the power consumption P of the condensing unit 2, is pre-stored in the diagnostic data section 31. Then, when the degradation diagnosis start time arrives, the sum of the temperature difference TD between the internal temperature T and the set temperature T0 within a predetermined period ending at that time is calculated as the temperature difference sum value ΣTD, the normal power amount PN corresponding to the calculated temperature difference sum value ΣTD is read from the diagnostic data section 31, and the degree of degradation of the cooling device is diagnosed based on a comparison between the actual power consumption P and the read normal power amount PN.

[0032] When the power consumption P of the condensing unit 2 becomes relatively high due to a disturbance, such as an increase in the internal temperature T caused by the intrusion of high-temperature outside air, the sum of the temperature difference TD between the internal temperature T and the set temperature T0, i.e., the total temperature difference value ΣTD, increases. Accordingly, the normal power consumption PN also increases. Therefore, the power consumption P does not deviate significantly from the normal power consumption PN, and the cooling device is correctly diagnosed as having no (small) deterioration. On the other hand, when the power consumption P becomes relatively high despite a small total temperature difference value ΣTD in an environment with few disturbances, the normal power consumption PN becomes smaller than in the previous case. Therefore, the power consumption P deviates significantly from the normal power consumption PN, and the cooling device is correctly diagnosed as having deterioration. In other words, according to this embodiment, an increase in the power consumption P due to disturbances surrounding the cooling device can be excluded from the indication of deterioration of the cooling device, and only other fluctuations in the power consumption P can be considered as indications of deterioration. This allows the degree of deterioration of the cooling device to be accurately diagnosed without being affected by disturbances.

[0033] In this embodiment, the cooling device is determined to be degraded not only when the power consumption P exceeds the allowable range but also when it falls below the allowable range, thereby enabling early detection of a wider variety of cooling device degradation. Furthermore, in this embodiment, when the power consumption P falls below the allowable range, the type of cooling device degradation is estimated to be a refrigerant leak or poor air circulation in the refrigerator compartment 6. More specifically, the system compares the power consumption P with the normal power consumption PN from the time the power consumption P fell below the allowable range up to a predetermined reference point. If the power consumption P has exceeded the normal power consumption PN since the reference point, the system estimates a refrigerant leak in the cooling device. If the power consumption P has consistently been below the normal power consumption PN since the reference point, the system estimates poor air circulation in the refrigerator compartment. In this way, being able to estimate the type of degradation before dispatching a worker to repair the cooling device allows the worker to prepare the necessary tools and parts in advance and quickly identify the type of cooling device degradation at the work site.

[0034] In the above embodiment, a cooling device in which the condensing unit 2 is separate from the refrigerated showcase 1 has been described, but the present invention can also be applied to a cooling device in which the condensing unit 2 is housed in the machine room of the refrigerated showcase 1. Furthermore, in addition to the refrigerated open showcase shown in the above embodiment, the present invention can be applied to various cooling devices, such as a sealed showcase in which the opening of the display chamber 7 is opened and closed by a door, or a refrigerator. [Explanation of symbols]

[0035] 1 refrigerated showcase 2 Condensing Unit 6 Inside the cabinet 11. Internal temperature sensor 12 Evaporator 13 Circulation fan 23 Temperature analysis section 24 Comparison and Judgment Section 27 Temperature data section 30 Power meter 31 Diagnostic Data Section

Claims

1. an evaporator (12) disposed in a compartment (6) for storing an object to be cooled; a condensing unit (2) that delivers refrigerant to an evaporator (12); A deterioration diagnosis system for a cooling device having an internal temperature sensor (11) for detecting the temperature inside the cabinet (6); a power meter (30) for measuring the amount of power consumed (P) by the condensing unit (2) within a predetermined period; a temperature data unit (27) for recording the temperature (T) inside the refrigerator at each predetermined time interval detected by the temperature sensor (11) and the set temperature (T0) inside the refrigerator (6) at that time in association with each other; a diagnostic data section (31) for storing a normal power amount (PN) which is a normal value of the power consumption amount (P); a temperature analysis unit (23) that, when it is time to start the deterioration diagnosis, acquires from a temperature data unit (27) the inside temperature (T) detected within the predetermined period ending at that time and the set temperature (T0) associated therewith, and calculates a sum of the temperature differences (TD) between the corresponding inside temperature (T) and the set temperature (T0) as a temperature difference sum value (ΣTD); a comparison and determination unit (24) that acquires the power consumption (P) within the predetermined period ending at the start time from a power meter (30), reads out a normal power consumption (PN) corresponding to the temperature difference sum value (ΣTD) calculated by a temperature analysis unit (23) from a diagnostic data unit (31), and determines the degree of deterioration of the cooling device based on a comparison between the acquired power consumption (P) and the read normal power consumption (PN); A deterioration diagnosis system for a cooling device, comprising:

2. 2. The cooling device deterioration diagnosis system according to claim 1, wherein the comparison and determination unit (24) determines that the cooling device is deteriorated when the power consumption (P) acquired from the power meter (30) exceeds or falls below an allowable range set based on the normal power consumption (PN).

3. The deterioration diagnosis system for a cooling device according to claim 2, wherein the comparison and determination unit (24) estimates that the type of deterioration of the cooling device is a refrigerant leak or poor air circulation inside the storage unit (6) when the power consumption (P) falls below the allowable range.

4. 4. The deterioration diagnosis system for a cooling device according to claim 3, wherein the comparison and determination unit (24), when the power consumption (P) falls below the allowable range, refers to a comparison result between the power consumption (P) and the normal power consumption (PN) from that point forward up to a predetermined reference point, and if the power consumption (P) has exceeded the normal power consumption (PN) since the reference point, it is determined that there is a refrigerant leak in the cooling device, and if the power consumption (P) has always been below the normal power consumption (PN) since the reference point, it is determined that there is poor air circulation inside the storage unit (6).

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