JP2006010126A - Freezing and refrigerating unit and refrigerator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a freezing and refrigerating unit that can avoid such a failure as to cause a sudden stop of cooling as much as possible by detecting the leakage of a refrigerant before the load of a compressor increases after air flows in even if piping is damaged at a low-pressure side, such as the connection section to an evaporator 22, and can secure high safety by using a flammable refrigerant having a small global warming coefficient and a refrigerator using the same. <P>SOLUTION: R290 or a mixed refrigerant with R290 as a main constituent is used as a refrigerant, and an evaporation temperature sensor 23 for detecting the piping temperature of the evaporator 22 is provided, thus determining that the refrigerant has leaked when the detection temperature of the evaporator temperature sensor is equal to or smaller than the boiling point of the refrigerant, and hence shifting to control corresponding to the leakage. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a refrigeration unit in which a compressor and a condenser of a cooling system are installed at the upper part of the gantry and an evaporator is installed in the lower part of the gantry, and a large commercial refrigerator / freezer having the refrigeration unit at the upper part of the main body. It is.

  Conventionally, in a commercial large-sized refrigerator-freezer exceeding 500 L, a refrigerator-freezer unit using a high-capacity compressor of 300 W or more is used. In particular, in the system for cooling the freezer compartment, a low boiling point refrigerant such as R22 or R404A that can provide a high refrigerating capacity even when the evaporation temperature is low is used.

  However, in recent years, from the viewpoint of preventing global warming, it has been desired to switch from chlorofluorocarbon refrigerants such as R22 and R404A, which have a high global warming potential, to natural refrigerants such as R290 and R600a, and to reduce CO2 emissions. For large-sized freezer refrigerators for business use with a large amount of electric power, it is desired to save energy as soon as possible.

  Here, commercial large-sized refrigerator-freezers have a large amount of refrigerant enclosed, and because there is a lot of fire as an ignition source in the surrounding kitchen environment, careful consideration is being given to the application of flammable natural refrigerants. . In home refrigerators, a technique for detecting leakage when refrigerant piping is damaged and flammable natural refrigerant leaks has been studied (for example, see Patent Document 1).

  Hereinafter, the conventional refrigerator will be described with reference to the drawings.

  FIG. 4 is a cross-sectional view of a conventional refrigerator described in Patent Document 1.

  As shown in FIG. 4, it is composed of a freezer compartment 1, a door 2, and a cabinet 3. In the upper part of the cabinet 3, a unit base 5 for fixing the freezing / refrigeration unit 4 and a cooling room 6 for cooling the freezing room 1 are installed.

  The refrigeration unit 4 includes a compressor 7 having a reciprocating type compression mechanism, a condenser 8, a capillary 9 as a decompression means, an evaporator 10, a suction pipe 11 of the compressor 7, a condensing fan 12, and an evaporating fan 13. Become. A drain 14 for discharging the defrost water in the cooling chamber 6 is embedded in the back surface of the cabinet 3.

  Further, a radiant heater 15 attached to the lower part of the evaporator 10, an evaporation temperature sensor 16 attached to a refrigerant pipe (not shown) of the evaporator 10, and an outlet temperature sensor 17 attached to the upper part of the evaporator 10. And the indoor temperature sensor 18 attached to the upper part of the freezer compartment 1 is installed.

  Next, the operation of the refrigeration unit 4 will be described. R600a which is a low boiling point refrigerant is used as the refrigerant. The refrigerant R <b> 600 a is compressed by the compressor 7, condensed by the condenser 8, depressurized by the capillary 9, and sent to the evaporator 10. Then, after being evaporated by the evaporator 10, it is refluxed to the compressor 7 through the suction pipe 11. At this time, the capillary 9 and the suction pipe 11 are subjected to heat exchange, and the cold and waste heat of the refrigerant returning to the compressor 7 is recovered.

  At this time, the condensation temperature of the refrigerant R600a is about 40 ° C. (about 5.3 atm) during normal operation at an ambient temperature of 30 ° C. and an indicated value of the indoor temperature sensor 18 in the freezer compartment 1 (hereinafter referred to as the room temperature) −20 ° C. The evaporation temperature is about −30 ° C. (about 0.5 atm).

  Then, the elapsed time after activation or defrosting is accumulated, and whenever the accumulated time exceeds about 10 hours, the compressor 7 is stopped and the radiant heater 15 is energized to defrost the evaporator 10. At this time, when the outlet temperature sensor 17 detects about 5 ° C., it is determined that the defrosting is completed, and energization of the radiant heater 15 is stopped.

  Further, when the difference between the indication values of the evaporation temperature sensor 16 and the outlet temperature sensor 17 becomes larger than 5 ° C., for example, at the indoor temperature −20 ° C. and the indication value −30 ° C. of the evaporation temperature sensor 16, When the indicated value is higher than −25 ° C., it is determined that the refrigerant has leaked, and the compressor 7 is stopped, and the fact that the refrigerant has leaked is notified.

  When the refrigerant leaks to the outside, the cooling capacity is reduced and the cooling tendency tends to be slow. At the outlet of the evaporator 10, the refrigerant is completely vaporized, and the temperature rises to near the temperature of the indoor air flowing into the evaporator 10 as superheated steam. To do. That is, when refrigerant leakage is detected based on the difference between the indication values of the evaporation temperature sensor 16 and the outlet temperature sensor 17 being larger than a predetermined value of 5 ° C., the refrigerant is detected at a relatively early stage in which a slow cooling tendency occurs. It is possible to notify that a leak has occurred.

As a result, the user can confirm the leakage of the refrigerant, stop using the fire, or make a service call so that the user can respond quickly and improve safety.
JP-A-9-14811

  However, the above conventional refrigerator detects refrigerant leakage on the premise that the cooling capacity is reduced and the refrigerant becomes superheated steam at the outlet of the evaporator 10, but in a commercial large refrigerator, Since the frequency of door opening and closing is high, if refrigerant leakage occurs during use, the evaporation capacity of the evaporator 10 is reduced due to frost formation, causing a problem that the refrigerant hardly becomes superheated steam at the outlet of the evaporator 10.

  Further, since the conventional refrigerator uses R600a which is a high boiling point refrigerant, the low pressure is lower than the atmospheric pressure, and if the pipe is damaged at the connection part of the evaporator 10, the air is not leaked before the refrigerant leaks. Flows in, the high pressure rises and the cooling capacity decreases, and in the worst case, an overload occurs due to air compression, and the compressor 7 stops and does not restart and may become uncooled. .

  That is, when R600a, which is a high boiling point refrigerant, is used, if the pipe is damaged on the low pressure side such as the connection part of the evaporator 10, the compressor 7 is stopped due to air compression and cannot be restarted, and the refrigerant is discharged from the damaged part of the pipe. There is a possibility that the refrigerant will continue to leak, and the refrigerant leakage cannot be detected only by using the difference between the indication values of the evaporation temperature sensor 16 and the outlet temperature sensor 17 as a reference. Therefore, when R600a which is a high boiling point refrigerant is used, a measure for determining that the refrigerant has leaked when the overload of the compressor 7 continues or when the start and stop are repeated due to the overload has been proposed.

  On the other hand, a large commercial refrigerator is required to have a higher cooling capacity and a higher load than a household refrigerator, and to continue a minimum cooling operation even when a failure occurs. That is, it is necessary to avoid as much as possible a failure in which overload occurs due to air compression and the compressor 7 stops and does not restart and suddenly becomes uncooled.

  Here, the compression ratio, the high pressure pressure, the low pressure pressure at a condensation temperature of 40 ° C., an evaporation temperature of −30 ° C., a supercooling of 0 ° C., and an intake gas temperature of 32 ° C., which are general operating conditions of a commercial refrigerator ambient temperature of 30 ° C. Table 1 shows the results of comparing the relative values of theoretical efficiency and volume capacity with R600a, which is a high boiling point refrigerant, and other refrigerants.

  As shown in Table 1, R22, R290, and R404A, which are low-boiling refrigerants compared to the high-boiling refrigerants R134a and R600a, have low theoretical efficiency, but have a low compression ratio and a high volume capacity, and an evaporation pressure. It can be seen that it is higher than atmospheric pressure. That is, R22, R290, and R404A, which are low-boiling refrigerants, do not cause air compression immediately when the piping is damaged on the low-pressure side such as the connection portion of the evaporator 10, but air compression does not occur. There is a possibility that the evaporating temperature is lowered and air flows in after a large amount of refrigerant leaks during defrosting of the vessel 10.

  Therefore, in large refrigerators for business use, R22, R290, and R404A, which are low boiling point refrigerants, are used, and early detection and notification of refrigerant leaks and suppression of refrigerant leaks can also be used. It is expected to continue the minimum cooling operation.

  The present invention solves the above-described conventional problems, and even when a pipe is damaged on the low pressure side such as a connection portion of an evaporator, an overload occurs due to air compression, and the compressor stops and does not restart. It is an object of the present invention to provide a freezer / refrigeration unit and a refrigerator that avoid a failure that suddenly becomes uncooled as much as possible.

  In order to solve the above conventional problems, the refrigeration unit and refrigerator of the present invention have a large volume capacity as a refrigerant and a boiling point of about -40 ° C, which is about 10 ° C lower than the evaporation temperature of -30 ° C during normal operation. R290 or a mixed refrigerant mainly composed of R290 is used, and an evaporation temperature sensor that detects the piping temperature of the evaporator is provided. When the detected temperature of the evaporation temperature sensor is below the boiling point of the refrigerant, it is determined that the refrigerant leaks, It shifts to leakage countermeasure control.

  As a result, a high cooling capacity can be obtained, and even if the piping is damaged on the low pressure side such as the connection part of the evaporator when frosting becomes remarkable during use and the evaporation capacity of the evaporator is reduced, the evaporation pressure of R290 is negative. By determining leakage based on the evaporation temperature in the vicinity of the boiling point that becomes the pressure, the evaporation temperature is significantly lower than the evaporation temperature of -30 ° C during normal operation before air flows in and the load on the compressor increases. As a result, the leakage of the refrigerant can be detected.

  The refrigeration unit and refrigerator of the present invention are compressed by inflowing air even when piping is damaged on the low-pressure side such as the connection part of the evaporator when frost formation becomes remarkable during use and the evaporation capacity of the evaporator decreases. Since refrigerant leakage can be detected before the load on the machine increases, it is possible to avoid as much as possible the trouble that causes overload due to air compression and the compressor stops and does not restart and suddenly becomes cold. In addition, it is possible to ensure high safety while using a flammable refrigerant with a small global warming potential.

  The invention according to claim 1 of the present invention uses a refrigerant mixture mainly composed of R290 or R290 as a refrigerant, and further includes an evaporation temperature sensor for detecting the pipe temperature of the evaporator, and the detected temperature of the evaporation temperature sensor is When the temperature is below the boiling point of the refrigerant, it is judged that the refrigerant is leaking, and the control shifts to leakage countermeasures.It can provide high cooling capacity, and even if the piping is damaged on the low pressure side such as the evaporator connection during use. By determining leakage based on the evaporation temperature near the boiling point at which the evaporation pressure of R290 becomes negative, leakage of the refrigerant can be detected before the air flows in and the load on the compressor increases.

  The invention according to claim 2 further comprises an evaporation temperature sensor for detecting the piping temperature of the evaporator and a cold air temperature sensor for detecting the temperature of the cold air passing around the evaporator, in the invention of claim 1, When the temperature difference between the evaporating temperature sensor and the cold air temperature sensor is larger than a predetermined value and the detected temperature of the evaporating temperature sensor is below the boiling point of the refrigerant, it is determined that the refrigerant is leaking, and the control shifts to leakage countermeasure control. Yes, it is possible to detect the occurrence of abnormal frosting by comparing the temperature indication values of the evaporation temperature sensor and the cold air temperature sensor. Can be prevented.

  The invention according to claim 3 further performs leakage countermeasure control for notifying that the refrigerant leakage has occurred in addition to the invention according to claim 1 or 2, and the user confirms the leakage of the refrigerant. Thus, it is possible to respond quickly by stopping the use of fire or making a service call, and it is possible to avoid failures that suddenly become uncooled as much as possible and to ensure high safety.

  The invention according to claim 4 further performs leakage countermeasure control that extends the defrosting interval as compared with the normal control in addition to any one of the inventions according to claims 1 to 3, and the low pressure of the connection part of the evaporator or the like. When piping is damaged on the side, it is possible to suppress an increase in the leakage rate of the refrigerant due to a high pressure during defrosting.

  The invention according to claim 5 further includes a variable capacity compressor and an outside air temperature sensor that detects the outside air temperature in addition to any one of the inventions according to claim 1 to claim 4, and the outside air temperature and the setting in the cabinet are provided. Leakage control is performed for continuous operation at a predetermined capacity according to the temperature, and the variable pressure compressor is driven with the minimum required cooling capacity estimated from the indicated value of the outside air temperature sensor to reduce the evaporation pressure as much as possible. By keeping it high, it is possible to suppress the inflow of air due to a negative pressure during operation when the piping is damaged on the low pressure side such as the connection portion of the evaporator.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments.

(Embodiment 1)
FIG. 1 is a cross-sectional view of a refrigerator according to Embodiment 1 of the present invention. FIG. 2 is a schematic diagram of an evaporator used in the refrigerator according to the embodiment. FIG. 3 is a correlation diagram between the evaporation temperature of the refrigerant and the evaporation pressure. In addition, about the same structure as the past, the same number is attached | subjected and detailed description is abbreviate | omitted.

  As shown in FIG. 1, it is composed of a freezer compartment 1, a door 2 and a cabinet 3. In the upper part of the cabinet 3, a unit base 5 for fixing the freezing / refrigeration unit 20 and a cooling chamber 6 for cooling the freezing chamber 1 are installed. As the refrigerant, R290, which is a low boiling point refrigerant, is used.

  The refrigerating / refrigeration unit 20 has a reciprocating type compression mechanism and a variable capacity compressor 21 having a variable rotation speed of 30 to 80 rps, a condenser 8, a capillary 9 as a decompression means, an evaporator 22, and a variable capacity compressor. 21 includes a suction pipe 11, a condensing fan 12, an evaporating fan 13, an evaporating temperature sensor 23, and a cold air temperature sensor 24. A drain 14 for discharging the defrost water in the cooling chamber 6 is embedded in the back surface of the cabinet 3.

  As shown in FIG. 2, the evaporator 22 includes a refrigerant pipe 22, fins 31, and a sheathed heater 32. The sheathed heater 32 is energized when the evaporator 22 is defrosted to heat the evaporator 22. The evaporating temperature sensor 23 is attached to the refrigerant pipe 30 by the metal holder 25 and the cold air temperature sensor 24 is attached to the refrigerant pipe 30 by the resin holder 26 by cutting out a part of the windward side of the fin 31.

  The evaporation temperature sensor 23 is fixed by a metal holder 25 having high thermal conductivity, and detects the temperature of the refrigerant pipe 30, that is, the evaporation temperature of the refrigerant. Further, the cold air temperature sensor 24 is fixed by a resin holder 26 having low thermal conductivity, and detects a temperature close to the cold air temperature in the freezer compartment 1 by touching the ventilated air flowing in from the freezer compartment 1. When an abnormally large amount of frost is generated in the evaporator 22, the periphery of the evaporation temperature sensor 23 and the cold air temperature sensor 24 is covered with frost and lump ice, and both are close to the evaporation temperature of the refrigerant. Is detected.

  In a commercial refrigerator installed in a kitchen environment, dust and splashed oil in the air tends to adhere to the condenser 8 and cause clogging. In addition to reducing the influence of clogging, a filter (not shown) is attached to the front of the condenser 8. Further, in order to maintain the durability of the variable capacity compressor 21, a freezer temperature sensor (not shown) that detects the temperature in the freezer 1 so as not to continue to provide high capacity under severe conditions, An outside air temperature sensor (not shown) for detecting the ambient temperature of the refrigerator and a condensation temperature sensor (not shown) for detecting the condensation temperature of the refrigerant in the condenser 8 are installed, and the capacity variable type based on these temperatures The rotation speed of the compressor 21 is determined.

  Next, the operation of the refrigeration unit 20 will be described.

  When the door is frequently opened and closed and the room temperature of the freezer compartment 1 rises greatly, the variable capacity compressor 21 is driven at 80 rps, and the refrigerant R290 is compressed by the variable capacity compressor 21 and condensed by the condenser 8. Then, the pressure is reduced by the capillary 9 and sent to the evaporator 22. Then, after being evaporated by the evaporator 22, it is returned to the variable capacity compressor 21 through the suction pipe 11. At this time, the capillary 9 and the suction pipe 11 are subjected to heat exchange, and the cold and waste heat of the refrigerant returning to the variable capacity compressor 21 is recovered.

  Here, the cylinder capacity of the variable capacity compressor 21 is designed to be about 1/3 that of a conventional refrigerator compressor using R600a which is a high boiling point refrigerant, and R290 which is three times the volume capacity of R600a. In the present embodiment using the above, it is possible to exhibit the same cooling capacity as before.

  And if the room temperature of the freezer compartment 1 falls and falls below +1.5 degreeC of setting temperature-20 degreeC, the rotation speed of the capacity variable type compressor 21 will be reduced one by one from 80 rps to 30 rps every predetermined time. Furthermore, when the room temperature of the freezer compartment 1 falls and falls below −2 ° C. of the set temperature −20 ° C., the operation of the variable capacity compressor 21 is stopped.

  At this time, the condensing temperature of the refrigerator of this embodiment using the refrigerant R290 during the normal operation at the ambient temperature of 30 ° C. and the indoor temperature of the freezing chamber −20 ° C. is about 40 ° C. (about 14 atm), and the evaporation temperature is about Whereas it is −30 ° C. (about 1.7 atm), the condensation temperature of the conventional refrigerator using the refrigerant R600a is about 40 ° C. (about 5.3 atm), and the evaporation temperature is about −30 ° C. (about 0 atm). .5 atm). Therefore, when the piping is damaged on the low pressure side such as the connection part of the evaporator 22, the conventional refrigerator using the refrigerant R600a immediately flows in air because the pressure during normal operation is negative. In the refrigerator of this embodiment, since the pressure during normal operation is positive, air does not flow in immediately, and when the refrigerant flows out during operation or when the evaporator 22 is defrosted and the evaporation temperature decreases, Air flows in only when the evaporating temperature is reduced due to frost formation.

  In the present embodiment, the air flow rate of the condenser fan 12 and the cooler fan 13 during the cooling operation is constant. However, even if the air flow rate of the condenser fan 12 and the cooler fan 13 is reduced as the cooling capacity is lowered, Good. By reducing the air volume of the condenser fan 12 and the cooler fan 13, energy saving of the fan input can be achieved.

  In this embodiment, the minimum rotation speed of the variable capacity compressor 21 is set to 30 rps. However, when the set temperature of the freezer compartment 1 is low and the ambient temperature is high, the cooling load is large and the indoor temperature of the freezer compartment 1 is lowered. Therefore, it is desirable to determine the minimum number of revolutions based on the ambient temperature and the set temperature.

  Next, the functions of the evaporation temperature sensor 23 and the cold air temperature sensor 24 when refrigerant leakage occurs during normal operation will be described.

  The solid line in FIG. 3 shows the correlation between the evaporation temperature and the evaporation pressure of the refrigerant R290, and the dotted line shows the correlation between the evaporation temperature and the evaporation pressure of the refrigerant R600a. The refrigerant evaporating temperature is about −30 ° C. during normal operation at an ambient temperature of 30 ° C. and the freezer compartment 1 indoor temperature of −20 ° C. The state of the refrigerant R290 at this time is point A in FIG. 3, and the evaporation pressure is about 170 kPa.

  On the other hand, the detection temperature of the evaporation temperature sensor 23 is about −30 ° C., and the detection temperature of the cold air temperature sensor 24 is about −25 ° C. The evaporating temperature sensor 23 is substantially the same as the evaporating temperature of the refrigerant, but the cold air temperature sensor 24 shows a value approximately in the middle of the evaporating temperature of the refrigerant and the temperature of the cold air flowing into the evaporator 22.

  Here, when the piping is damaged on the low pressure side such as the connection portion of the evaporator 22, a part of the refrigerant leaks, the cooling capacity is lowered, and the evaporation pressure is lowered. At this time, in order to compensate for the reduced cooling capacity, that is, to suppress the increase in the room temperature of the freezer compartment 1, the rotation speed of the variable capacity compressor 21 increases and the evaporation pressure further decreases. As a result, the pressure decreases to the state indicated by point B in FIG. 3 and the evaporation pressure of about 100 kPa (atmospheric pressure). The evaporation temperature of the refrigerant R290 at this time is about −42 ° C.

  The detected temperature of the evaporating temperature sensor 23 decreases with the evaporating temperature of the refrigerant to indicate about −42 ° C., and the detected temperature of the cool air temperature sensor 24 also decreases with the evaporating temperature of the refrigerant to indicate about −30 ° C. The reason why the temperature drop of the cold air temperature sensor 24 is small is that the temperature of the cold air flowing into the evaporator 22 is not greatly changed to about −20 ° C. If the cooling load of the freezer compartment 1 increases at the same time and cannot cope with the increase in the rotational speed of the variable capacity compressor 21, the indoor temperature of the freezer compartment 1 rises, and the indicated value of the cold air temperature sensor 24 further increases. growing.

  At this time, the indicated value of the evaporation temperature sensor 23 decreases to the boiling point of the refrigerant R290, that is, near the evaporation temperature of atmospheric pressure, and the difference between the indicated values of the evaporation temperature sensor 23 and the cold air temperature sensor 24 is 5 in the normal operation. Since it is higher than ° C., it is detected that the refrigerant has leaked, and the control shifts to leak handling control.

  As leakage countermeasure control, it is desirable to notify a warning lamp, a warning buzzer, an error display, etc., extend the defrosting interval, and reduce the rotation speed of the variable capacity compressor 21. By notifying, the user can confirm the leakage of the refrigerant, stop using the fire, or make a service call to respond quickly and avoid danger, ensuring high safety it can. Moreover, the refrigerant | coolant leakage speed can be suppressed by reducing the frequency | count of the defrost which the pressure of the evaporator 22 increases. In addition, by driving the variable capacity compressor 21 at the minimum number of rotations at which the normal operation is possible at the outside air temperature, the evaporation pressure is further reduced to a negative pressure, and air is sucked to cause overload. The worst situation in which the variable compressor 21 is stopped and cannot be restarted can be avoided.

  As a comparative example, when the refrigerant R600a is used and the piping is damaged on the low pressure side such as the connection portion of the evaporator 22, the intake of air is started from the point of damage and the load of the variable capacity compressor 21 increases. I will do it. This is because, as indicated by point C in FIG. 3, the refrigerant R600a has a negative pressure (about 46 kPa) even during normal operation. Further, in this case, unless the capacity variable compressor 21 is stopped, the refrigerant hardly leaks, and the evaporating temperature sensor 23, the cold air temperature sensor 24, and the outlet temperature of the evaporator 22 hardly change, so that an abnormality is detected. It is difficult. When the load of the variable capacity compressor 21 exceeds the limit, the compressor 21 stops and enters a state where it cannot be restarted. As a result, it becomes non-cooled, the room temperature of the freezer compartment 1 rises while the capacity variable compressor 21 is stopped, and the refrigerant continues to leak from the point of exceeding point D (about −11 ° C.) in FIG. Become.

  Next, functions of the evaporation temperature sensor 23 and the cold air temperature sensor 24 when abnormal frosting occurs will be described.

  If the door is opened and closed frequently during normal operation, or if the door is closed for a long time and is operated for a long time, an abnormally large amount of frost adheres to the windward side of the evaporator 22. Moreover, in such a case, since the room | chamber interior of the freezer compartment 1 becomes high humidity, the adhering frost turns into blocky ice.

  At this time, the evaporation capability of the evaporator 22 decreases, and the evaporation temperature of the refrigerant decreases. At the same time, the evaporating temperature sensor 23 and the cold air temperature sensor 24 are lowered to show substantially the same temperature. This is because the periphery of the evaporation temperature sensor 23 and the cold air temperature sensor 24 is covered with high-density lump ice.

  As a result, even if the indicated value of the evaporation temperature sensor 23 decreases to the boiling point of the refrigerant R290, that is, near the evaporation temperature of atmospheric pressure, the difference between the indicated values of the evaporation temperature sensor 23 and the cold air temperature sensor 24 is 5 Since it becomes smaller than ° C., it is not determined that the refrigerant has leaked. Accordingly, it is possible to prevent a false detection that occurs when it is detected that the refrigerant has leaked based only on the fact that the indication value of the evaporation temperature sensor 23 has dropped to the boiling point of the refrigerant R290, that is, the vicinity of the evaporation temperature at atmospheric pressure. Can do.

  As described above, R290 or a mixed refrigerant mainly composed of R290 is used as the refrigerant, and the evaporating temperature sensor for detecting the piping temperature of the evaporator and the cold air temperature sensor for detecting the temperature of the cold air passing around the evaporator are provided. When the temperature difference between the evaporating temperature sensor and the cold air temperature sensor is larger than normal, and when the detected temperature of the evaporating temperature sensor is below the boiling point of the refrigerant, it is determined that the refrigerant is leaking and the control is shifted to the leakage control. Therefore, even if the piping is damaged on the low pressure side such as the connection part of the evaporator, before the air flows in and the load on the compressor increases, it is possible to detect a refrigerant leak and suddenly become cold. While avoiding as much as possible, high safety can be secured while using a flammable refrigerant with a low global warming potential.

  In the present embodiment, the freezer compartment 1 that is normally set to −15 ° C. to −25 ° C. is targeted, but the same effect can be obtained even when a storage room set at 5 ° C. or higher, for example, a refrigerator compartment is cooled. It is done. In this case, the evaporation temperature during normal operation is −10 ° C. to −15 ° C. and increases by 15 ° C. to 20 ° C. compared to the present embodiment. Therefore, for example, R600a, which is a high boiling point refrigerant, is used as the main component. It is desirable to use a mixed refrigerant having a mixed boiling point of about -30 ° C. If the difference between the evaporation temperature and the boiling point during normal operation is too large, the amount of refrigerant leaking before detection increases, which is not preferable for safety.

  In this example, abnormal frost formation was detected and the refrigerant leakage determination was denied, but the indication values of the evaporation temperature sensor and the cold air temperature sensor were substantially the same and greatly decreased than the evaporation temperature during normal operation. In such a case, it is desirable to determine the abnormal frost formation and to defrost the evaporator. When abnormal frost formation and refrigerant leakage occur at the same time, it is possible to avoid delaying the refrigerant leakage determination.

  In this embodiment, the evaporating temperature sensor and the cold air temperature sensor are individually installed on the upper windward side of the evaporator, but may be installed on the same pipe using one holder. Moreover, you may detect the completion | finish of defrosting of the evaporator normally implemented with a bimetal etc. using an evaporation temperature sensor or a cold temperature sensor.

  The refrigerator-freezer unit and refrigerator according to the present invention have a low global warming potential and a high volumetric capacity even when the refrigerant leaks by using R290 as the refrigerant, and the refrigerant leaked during operation. Because it is possible to improve safety by detecting this quickly, it is necessary for high-capacity use, and there is a high possibility that fires such as kitchens are used in the surroundings. It can be applied as a cooling system for equipment.

Sectional view of a refrigerator according to the invention Schematic diagram of refrigerator evaporator according to the present invention Correlation diagram of refrigerant evaporation temperature and evaporation pressure Cross-sectional view of a conventional refrigerator

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Freezer compartment 5 Unit base 20 Refrigeration / refrigeration unit 21 Variable capacity compressor 22 Evaporator 23 Evaporation temperature sensor 24 Cold air temperature sensor

Claims (5)

  R290 or a mixed refrigerant containing R290 as a main component is used as a refrigerant, and an evaporation temperature sensor for detecting the temperature of the piping of the evaporator is provided. If the detected temperature of the evaporation temperature sensor is below the boiling point of the refrigerant, it is determined that the refrigerant is leaking. And a refrigerator using the refrigerator-freezer unit, wherein the refrigerator-freezer unit is shifted to leakage countermeasure control.   An evaporation temperature sensor for detecting the piping temperature of the evaporator and a cold air temperature sensor for detecting the temperature of the cold air passing around the evaporator are provided, and a temperature difference between the evaporation temperature sensor and the cold air temperature sensor is larger than a predetermined value. 2. The refrigeration unit and the refrigeration unit according to claim 1, wherein when the detected temperature of the evaporating temperature sensor is equal to or lower than the boiling point of the refrigerant, it is determined that the refrigerant is leaking, and the control is shifted to leakage countermeasure control. Fridge.   The refrigerating / refrigeration unit according to claim 1 or 2, and a refrigerator using the refrigerating / refrigeration unit, wherein leakage control is performed to notify that a refrigerant leak has occurred.   The refrigerator using the refrigeration unit according to any one of claims 1 to 3, and the refrigerator using the refrigeration unit, wherein leakage countermeasure control is performed to extend a defrosting interval as compared with normal control.   The apparatus according to claim 1, further comprising a variable capacity compressor and an outside air temperature sensor that detects outside air temperature, and performing leakage countermeasure control that continuously operates at a predetermined capacity according to the outside air temperature and a set temperature in the refrigerator. 4. The refrigerator as described in any one of 4.

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