Cooling Storage

Abstract

To provide a cooling storage warehouse capable of reducing consumption of electric energy for defrosting operation.SOLUTION: A control section of a cooling storage warehouse performs defrosting operation until a temperature detected by a defrosting temperature sensor becomes a first defrosting termination temperature which is a temperature to terminate defrosting operation when at least one condition selected from the following four conditions is met: a first condition in which the number of times that a storage temperature detected by a storage temperature sensor becomes equal to or higher than a door opening-closing detection temperature, is equal to or less than the reference number of times during cooling operation; a second condition in which a set storage temperature becomes equal to or higher than a reference set temperature during the cooling operation; a third condition in which a difference between the storage temperature detected by the storage temperature sensor and the set storage temperature becomes equal to or less than a reference value during the cooling operation; and a fourth condition in which the temperature detected by the defrosting temperature sensor becomes equal to or higher than a reference defrosting temperature during the cooling operation. When any of the condition selected from the four conditions is met, the control section performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes a first defrosting termination temperature which is a temperature to terminate the defrosting operation. When any of the condition selected from the four conditions is not met, the control section performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes a second defrosting termination temperature which is a temperature to terminate the defrosting operation and higher than the first defrosting termination temperature.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a cooling storage facility. [Background technology]

[0002] Conventionally, a refrigerator that is an example of a cooling storage is known, as described in the following Patent Document 1. The refrigerator described in Patent Document 1 is a refrigerator that includes an outside air temperature sensor that detects the outside air temperature, a defrost temperature sensor that detects the temperature of a cooler or its vicinity, and a control unit that terminates a defrosting operation when the temperature detected by the defrost temperature sensor reaches a defrosting set temperature for determining the completion of defrosting, and the control unit determines whether the temperature detected by the outside air temperature sensor is lower than a first set temperature or higher than a second set temperature that is higher than the first set temperature, and when the temperature is lower than the first set temperature or higher than the second set temperature, the control unit sets the defrosting set temperature for determining the completion of defrosting to the first defrosting set temperature for determining the completion of defrosting and performs a defrosting operation, and when the temperature is between the first set temperature and the second set temperature, the control unit sets the defrosting set temperature for determining the completion of defrosting to the second defrosting set temperature for determining the completion of defrosting that is lower than the first defrosting set temperature and performs a defrosting operation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6270375 Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned Patent Document 1, the defrost setting temperature for judging the end of defrosting is varied based on the outside air temperature detected by the outside air temperature sensor. However, since the influence of the outside air temperature on the temperature environment inside the storage unit and the amount of frost on the cooler differs depending on the insulation performance of the storage unit body and the frequency of opening and closing the door, even if the defrost setting temperature is set based on the outside air temperature as in Patent Document 1, there is a risk that it is not possible to perform an appropriate defrosting operation according to the actual amount of frost on the cooler. For this reason, there is a risk that power consumption cannot be sufficiently saved.

[0005] The technology described in this specification was developed based on the above circumstances, and aims to reduce power consumption. [Means for solving the problem]

[0006] (1) A cooling storage cabinet according to the technology described in this specification includes a storage cabinet body having an opening, a door for opening and closing the opening, a first sensor for detecting an internal temperature, an evaporator constituting a refrigeration cycle, a heating unit for heating the evaporator, a second sensor for detecting a temperature of the evaporator or the vicinity of the evaporator, and a control unit for controlling the refrigeration cycle to perform a cooling operation so that the internal temperature detected by the first sensor becomes an internal set temperature, and for controlling the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature, and the control unit detects the opening and closing of the door when the internal temperature detected by the first sensor becomes equal to or higher than a predetermined door opening / closing detection temperature, and detects the internal temperature detected by the first sensor during the cooling operation. When at least one selection condition is satisfied, selected from a first condition that the number of times that the internal temperature becomes equal to or higher than the door opening / closing detection temperature is equal to or lower than a reference number of times, a second condition that the internal temperature setting during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the internal temperature detected by the first sensor during the cooling operation and the internal temperature setting is equal to or lower than a reference value, and a fourth condition that a temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrost temperature, the defrost operation is performed until the temperature detected by the second sensor becomes a first defrost end temperature that is the defrost end temperature, and when the selection condition is not satisfied, the defrost operation is performed until the temperature detected by the second sensor becomes a second defrost end temperature that is higher than the first defrost end temperature.

[0007] When the cooling operation is performed by the control unit, the refrigeration cycle is controlled so that the air inside the storage compartment is cooled by the evaporator, and the storage compartment temperature detected by the first sensor becomes the storage compartment set temperature. When the defrosting operation is performed by the control unit, the heating unit is controlled so that the evaporator is heated until the temperature detected by the second sensor becomes the defrost end temperature. Here, if the heating unit is excessive compared to the amount of frost on the evaporator, problems occur such as an increase in the amount of power consumed by the heating unit and an increase in the storage compartment temperature, which increases the amount of power consumed in the cooling operation. Conventionally, the defrost set temperature for determining the end of defrost was varied based on the outside air temperature detected by the outside air temperature sensor, so there was a risk that an appropriate defrosting operation according to the actual amount of frost could not be performed depending on conditions such as the insulation performance of the storage compartment body and the number of times the door is opened and closed.

[0008] In this regard, when at least one of the selection conditions selected from the first condition, the second condition, the third condition, and the fourth condition is satisfied, the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrosting end temperature, and when the selection conditions are not satisfied, the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the second defrosting end temperature higher than the first defrosting end temperature. In detail, in the first condition, the number of times the door is opened and closed during the cooling operation is used as an index, and if the number of times the door is opened and closed is equal to or less than a reference number, the inflow of air with high humidity outside the refrigerator into the refrigerator is suppressed, so that it is estimated that the amount of frost on the evaporator is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is satisfied when the first condition is satisfied, it is possible to prevent the heating by the heating unit from becoming excessive compared to the amount of frost on the evaporator, and to reduce the amount of power consumption. In the second condition, the in-cabinet temperature setting before the defrosting operation is used as an index, and if the in-cabinet temperature setting is equal to or higher than the reference temperature setting, the refrigeration cycle can be operated at a low temperature, so that the evaporator temperature does not drop too low and it is estimated that the amount of frosting is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the second condition is met, it is possible to prevent the heating by the heating unit from becoming excessive compared to the amount of frosting on the evaporator, and it is possible to reduce the amount of power consumption. In the third condition, the difference between the in-cabinet temperature before the defrosting operation and the in-cabinet temperature setting is used as an index, and if the difference is equal to or lower than the reference value, it is possible to say that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frosting on the evaporator, and it is therefore estimated that the amount of frosting on the evaporator is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the third condition is met, it is possible to prevent the heating by the heating unit from becoming excessive compared to the amount of frosting on the evaporator, and it is possible to reduce the amount of power consumption. In the fourth condition, the temperature of the evaporator or its vicinity before the defrosting operation is used as an index, and if that temperature is equal to or higher than the reference defrosting temperature, it is estimated that the evaporator temperature has not dropped significantly, and therefore the amount of frost on the evaporator is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the fourth condition is satisfied, it is possible to prevent the heating by the heating unit from becoming excessive compared to the amount of frost on the evaporator, and to reduce the amount of power consumption.As described above, by varying the defrost end temperature based on whether or not at least one selection condition selected from the first condition, the second condition, the third condition, and the fourth condition is satisfied, an appropriate defrosting operation can be performed according to the amount of frost on the evaporator, thereby reducing power consumption.

[0009] (2) In addition to the above (1), the control unit may select whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature when performing the defrosting operation based on whether at least any of the first condition, the second condition, the third condition, and the fourth condition are satisfied. When the first condition, the second condition, the third condition, and the fourth condition are all satisfied, it can be said that there is an extremely high degree of certainty that the amount of frost formed on the evaporator is small. Therefore, if the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature, which is lower than the second defrost end temperature, only when the first condition, the second condition, the third condition, and the fourth condition are all satisfied, there is an extremely high degree of certainty that the heating by the heating unit is prevented from becoming excessive compared to the amount of frost formed on the evaporator, and power consumption can be reduced. In other words, even if there is a large amount of frost, the control unit is more likely to avoid performing defrosting operation until the temperature detected by the second sensor reaches the first defrost end temperature, making it less likely that defrosting will be insufficient, causing the evaporator to freeze, or that the cooling performance of the refrigeration cycle will decrease.

[0010] (3) In addition to the above (1) or (2), the control unit may select whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the first condition is satisfied when performing the defrosting operation, and the first condition may be that the number of times that the inside temperature detected by the first sensor becomes equal to or higher than the door opening / closing detection temperature during a set time during the cooling operation is equal to or less than a reference number. The first condition uses the frequency of door opening / closing during the cooling operation as an index, and if the frequency of door opening / closing is low, the inflow of high-humidity air from outside the storage compartment into the storage compartment is suppressed, so it is estimated that the amount of frost on the evaporator is small. Therefore, by making the defrost end temperature different based on whether or not the first condition is satisfied, it is possible to perform an appropriate defrosting operation according to the amount of frost on the evaporator. In addition, compared to the conventional method in which the defrosting operation was performed until the temperature detected by the second sensor reached the second defrost end temperature if the door was opened or closed even once during cooling operation, the power consumption can be more suitably reduced by varying the defrost end temperature based on whether the first condition, which uses the frequency of door opening and closing as an index, is satisfied. Also, since the opening and closing of the door is detected using the first sensor that detects the temperature inside the refrigerator, there is no need to install a switch on the door, as opposed to the case in which such a switch is installed to detect opening and closing.

[0011] (4) In addition to any one of (1) to (3), the control unit may select which of the first defrost end temperature and the second defrost end temperature is used as the defrost end temperature based on whether or not at least the third condition is satisfied when performing the defrosting operation, and the third condition may be that the difference between the inside temperature detected by the first sensor and the set inside temperature at least in the set time immediately before the defrosting operation is equal to or less than a reference value. In the third condition, the difference between the inside temperature and the set inside temperature in the set time immediately before the defrosting operation is used as an index. As a result, whether or not the heat exchange efficiency of the refrigeration cycle is reduced due to frosting on the evaporator at the stage immediately before the defrosting operation is accurately reflected in the difference between the inside temperature and the set inside temperature. Therefore, by making the defrost end temperature different based on whether or not the third condition is satisfied, an appropriate defrosting operation can be performed according to the amount of frosting on the evaporator.

[0012] (5) In addition to any one of (1) to (4), the control unit may select which of the first defrost end temperature and the second defrost end temperature is used as the defrost end temperature based on whether or not at least the fourth condition is satisfied when performing the defrosting operation, and the fourth condition may be that the temperature detected by the second sensor at a set time immediately before the defrosting operation is equal to or higher than a reference defrost temperature. In the fourth condition, the temperature of the evaporator or its vicinity at a set time immediately before the defrosting operation is used as an index. As a result, whether or not the amount of frost on the evaporator is large due to a temperature drop of the evaporator at a stage immediately before the defrosting operation is performed is accurately reflected in the temperature of the evaporator or its vicinity. Therefore, by making the defrost end temperature different based on whether or not the fourth condition is satisfied, an appropriate defrosting operation can be performed according to the amount of frost on the evaporator.

[0013] (6) In addition to any one of (1) to (5) above, the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a second condition is satisfied in addition to the selection condition, that is, an accumulated time during which the inside temperature detected by the first sensor during the cooling operation is equal to or less than the inside temperature set temperature, is equal to or greater than a reference accumulated time, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the second condition are not satisfied. In the second condition, the accumulated time during which the inside temperature is equal to or less than the inside temperature set temperature is used as an index, and if the accumulated time is equal to or greater than the reference accumulated time, it can be said that the cooling performance of the refrigeration cycle is properly exerted, the inside of the refrigeration cycle is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the evaporator, and therefore it is estimated that the amount of frost formation on the evaporator is small. Therefore, if the defrost end temperature is varied based on whether or not the second condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost formed on the evaporator.

[0014] (7) In addition to any one of (1) to (6), the cooling storage includes a compressor that constitutes the refrigeration cycle together with the evaporator, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a third condition is satisfied in addition to the selection condition, in which the number of times the compressor is stopped due to the inside temperature being equal to or lower than the inside temperature setting during the cooling operation is equal to or greater than a reference number, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the third condition are not satisfied. In the third condition, the number of times the compressor that constitutes the refrigeration cycle is stopped is used as an index, and if the number of times the compressor is stopped during the cooling operation is equal to or greater than a reference number, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the inside of the storage is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore it is estimated that the amount of frost formation on the evaporator is small. Therefore, if the defrost end temperature is varied based on whether or not the third condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the evaporator.

[0015] (8) In addition to any one of (1) to (7), the cooling storage includes a compressor that constitutes the refrigeration cycle together with the evaporator, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a fourth condition is satisfied in which the accumulated stop time of the compressor is equal to or longer than a reference stop time due to the inside temperature being equal to or lower than the inside temperature setting during the cooling operation in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the fourth condition are not satisfied. In the fourth condition, the accumulated stop time of the compressor is used as an index, and if the accumulated stop time of the compressor during the cooling operation is equal to or longer than the reference stop time, it can be said that the cooling performance of the refrigeration cycle is properly exerted even when the compressor is operating at a low speed, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore it is estimated that the amount of frost formation on the evaporator is small. Therefore, if the defrost end temperature is varied based on whether or not the fourth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost formed on the evaporator.

[0016] (9) In addition to any one of (1) to (8), the cooling storage includes a compressor that configures the refrigeration cycle together with the evaporator, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when the fifth condition is satisfied, in addition to the selection condition, that is, the average rotation speed of the compressor during the cooling operation is equal to or lower than a reference rotation speed, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the fifth condition are not satisfied. In the fifth condition, the average rotation speed of the compressor is used as an index, and if the average rotation speed of the compressor during the cooling operation is equal to or lower than a reference rotation speed, the cooling performance of the refrigeration cycle is properly exhibited even when the compressor is operating at a low speed, and the inside of the storage is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and it is estimated that the amount of frost formation on the evaporator is small. Therefore, if the defrost end temperature is made different based on whether the fifth condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frost formation on the evaporator can be performed.

[0017] (10) In addition to any one of (1) to (9), the cooling storage may include a compressor constituting the refrigeration cycle together with the evaporator, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a sixth condition is satisfied in which the average current value or power value of the compressor is equal to or lower than a reference value during the cooling operation in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the sixth condition are not satisfied. In the sixth condition, the average current value or power value of the compressor is used as an index, and if the average current value or power value of the compressor is equal to or lower than a reference value during the cooling operation, the cooling performance of the refrigeration cycle is properly exhibited even when the compressor is operating at a low speed, and the inside of the storage is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore the amount of frost formation on the evaporator is estimated to be small. Therefore, if the defrost end temperature is varied based on whether or not the sixth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the evaporator.

[0018] (11) In addition to any one of (1) to (10), the cooling storage is provided with an internal fan disposed in the storage body for circulating air inside the storage, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a seventh condition is satisfied in which the accumulated stop time of the internal fan becomes equal to or longer than a reference stop time due to the internal temperature becoming equal to or lower than the internal set temperature during the cooling operation in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the seventh condition are not satisfied. In the seventh condition, the accumulated stop time of the internal fan is used as an index, and if the accumulated stop time of the internal fan during the cooling operation is equal to or longer than the reference stop time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled even if the internal fan is operating at a low speed, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore it is estimated that the amount of frost formation on the evaporator is small. Therefore, if the defrost end temperature is varied based on whether or not the seventh condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the evaporator.

[0019] (12) Furthermore, in addition to any one of (1) to (11) above, the cooling storage cabinet may include a compressor which constitutes the refrigeration cycle together with the evaporator, and an internal fan which is arranged in the storage cabinet body and circulates air inside the cabinet, and the control unit may operate the internal fan at high speed while the compressor is operating, operate the internal fan at low speed while the compressor is stopped, and stop operation of the internal fan during the defrosting operation, and may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if an eighth condition is satisfied in addition to the selection condition, that is, an accumulated low-speed operation time of the internal fan during the cooling operation is equal to or longer than a standard operation time, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the eighth condition are not satisfied. The eighth condition uses the cumulative low-speed operation time of the interior fan, whose operation speed is controlled in synchronization with the operating state of the compressor, as an index, and if the cumulative low-speed operation time of the interior fan during cooling operation is equal to or longer than the reference operation time, it means that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled even if the compressor and the interior fan are operating at low speed, and it can be said that the heat exchange efficiency of the refrigeration cycle has not decreased significantly due to frost on the evaporator, and therefore it is estimated that the amount of frost on the evaporator is small. Therefore, if the defrost end temperature is made different based on whether the eighth condition is satisfied in addition to the selection condition, an appropriate defrost operation can be performed according to the amount of frost on the evaporator.

[0020] (13) In addition to any one of (1) to (12), the cooling storage is provided with an interior fan disposed in the storage body for circulating air inside the storage, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a ninth condition is satisfied in which an average current value or power value of the interior fan is equal to or lower than a reference value during the cooling operation in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the ninth condition are not satisfied. In the ninth condition, the average current value or power value of the interior fan is used as an index, and if the average current value or power value of the interior fan is equal to or lower than a reference value during the cooling operation, even if the interior fan is operating at a low speed, the cooling performance of the refrigeration cycle is appropriately exhibited and the interior is appropriately cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the evaporator, and therefore the amount of frost formation on the evaporator is estimated to be small. Therefore, if the defrost end temperature is varied based on whether or not the ninth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the evaporator.

[0021] (14) In addition to any one of (1) to (13), the cooling storage includes a condenser constituting the refrigeration cycle together with the evaporator, and a condenser fan blowing air to the condenser, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a tenth condition is satisfied in which an integrated stop time of the condenser fan during the cooling operation is equal to or longer than a reference stop time in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the tenth condition are not satisfied. In the tenth condition, an integrated stop time of the condenser fan blowing air to the condenser is used as an index, and if the integrated stop time of the condenser fan during the cooling operation is equal to or longer than a reference stop time, the cooling performance of the refrigeration cycle is properly exhibited even if the condenser fan is operating at a low speed, and the inside of the storage is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore the amount of frost formation on the evaporator is estimated to be small. Therefore, if the defrost end temperature is varied based on whether or not the tenth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost formed on the evaporator.

[0022] (15) In addition to any one of (1) to (14), the cooling storage includes a condenser constituting the refrigeration cycle together with the evaporator, and a condenser fan for blowing air to the condenser, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when an eleventh condition is satisfied in which an average current value or power value of the condenser fan is equal to or lower than a reference value during the cooling operation in addition to the selection condition, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the eleventh condition are not satisfied. In the eleventh condition, an average current value or power value of the condenser fan is used as an index, and if the average current value or power value of the condenser fan is equal to or lower than a reference value during the cooling operation, the cooling performance of the refrigeration cycle is properly exhibited even if the condenser fan is operating at a low speed, and the inside of the storage is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the evaporator, and therefore the amount of frost formation on the evaporator is estimated to be small. Therefore, if the defrost end temperature is varied based on whether or not the eleventh condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost formed on the evaporator.

[0023] (16) Furthermore, in addition to any one of (1) to (15) above, the cooling storage cabinet may further include a compressor which constitutes the refrigeration cycle together with the evaporator, a condenser which constitutes the refrigeration cycle together with the evaporator and the compressor, a condenser fan which blows air to the condenser, and a third sensor which detects the temperature of the condenser or near the condenser, and the control unit may perform the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a twelfth condition is satisfied in addition to the selection condition, that is, when an accumulated time during which the temperature detected by the third sensor during the cooling operation is lower than a reference temperature is equal to or longer than the reference accumulated time, and may perform the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the twelfth condition are not satisfied. The twelfth condition uses the cumulative time during which the temperature detected by the third sensor during cooling operation becomes lower than the reference temperature as an index, and if the cumulative time during cooling operation is equal to or longer than the reference cumulative time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior of the refrigerator is properly cooled even when the compressor is operating at a low speed, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost on the evaporator, and therefore it is estimated that the amount of frost on the evaporator is small. Therefore, if the defrost end temperature is made different based on whether the twelfth condition is satisfied in addition to the selection condition, an appropriate defrost operation can be performed according to the amount of frost on the evaporator. Effect of the Invention

[0024] According to the technology described in this specification, it is possible to reduce the amount of power consumption. [Brief description of the drawings]

[0025] [Figure 1] FIG. 1 is a front view of a freezer according to a first embodiment; [Diagram 2] A diagram showing the internal structure of the refrigerator from the right side [Diagram 3] Block diagram showing the electrical configuration of the freezer [Figure 4] A timing chart showing the cooling and defrosting operations of a freezer when the first condition is selected. [Diagram 5] A timing chart showing the cooling and defrosting operations of a freezer when the second condition is selected. [Figure 6] Timing chart showing cooling and defrosting operation of a freezer when the third condition is selected [Figure 7] A timing chart showing the cooling and defrosting operations of a freezer when the fourth condition is selected. [Figure 8] 1 is a timing chart showing the cooling and defrosting operations of a freezer when all of the first, second, third and fourth conditions are selected. [Figure 9] A timing chart showing the cooling operation and the defrosting operation of a freezer according to a second embodiment and explaining a first condition. [Figure 10] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the third embodiment and explaining the fourth condition. [Figure 11] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the fourth embodiment and explaining the second condition. [Figure 12] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the fifth embodiment and explaining the third condition. [Figure 13] FIG. 13 is a timing chart showing the cooling operation and the defrosting operation of the freezer according to the sixth embodiment and explaining the fourth condition. [Figure 14] FIG. 13 is a timing chart showing the cooling operation and the defrosting operation of the freezer according to the seventh embodiment and explaining the fifth condition. [Figure 15] FIG. 13 is a timing chart showing the cooling operation and the defrosting operation of the freezer according to the eighth embodiment and explaining the sixth condition. [Figure 16] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the ninth embodiment and explaining the seventh condition. [Figure 17] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the tenth embodiment and explaining the eighth condition. [Figure 18] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the eleventh embodiment and explaining the ninth condition. [Figure 19] A timing chart showing the cooling operation and the defrosting operation of a freezer according to a twelfth embodiment and explaining a tenth condition. [Figure 20] A timing chart showing the cooling operation and the defrosting operation of a freezer according to a thirteenth embodiment and explaining an eleventh condition. [Figure 21] A timing chart showing the cooling operation and the defrosting operation of the freezer according to the fourteenth embodiment and explaining the twelfth condition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] <Embodiment 1> In the first embodiment, a four-door freezer 10 will be described as an example of a cooling storage with reference to Figs. 1 to 8. As shown in Figs. 1 and 2, the freezer 10 includes a storage body 12, a door 14, a machine room 16, and a cooling device 18. The cooling device 18 is a device for cooling the inside of the storage body 12, and includes a compressor 22, a condenser 26 having a condenser fan 24, and a cooler (evaporator) 28. Note that Figs. 1 and 2 show arrows that serve as references for the up-down and left-right directions, with the upper side indicated as "U", the lower side indicated as "D", the right side indicated as "R", and the left side indicated as "L".

[0027] As shown in Fig. 2, the storage body 12 is an insulated box having an opening 12A opening to the front, and is configured by foaming and filling the space between an outer box 30 and an inner box 32 with insulating material. A storage chamber 34 and a cooler chamber 36 are provided inside the storage body 12 (i.e., inside the inner box 32). A plurality of shelves are provided in the storage chamber 34 on which stored items such as food ingredients are placed, and the cooler chamber 36 houses the cooler 28. The storage chamber 34 and the cooler chamber 36 are separated by a cooling duct 40.

[0028] The cooling duct 40 has an inclined portion 42 that inclines downward toward the rear. The inclined portion 42 of the cooling duct 40 has an intake port 42A on the front side and an exhaust port 42B on the rear side. An internal fan (circulation fan) 44 that circulates the air inside the refrigerator is provided above the intake port 42A in the cooler chamber 36. Furthermore, an internal temperature sensor (first sensor) 46 that detects the temperature inside the refrigerator is provided above the internal fan 44. The cooler 28 is disposed behind the internal fan 44. The cooler 28 is provided with a defrost heater (defrost heater, heating unit) 27 that can heat the cooler 28 during defrosting, and a defrost temperature sensor (second sensor) 29 that detects the temperature of the cooler 28 or near the cooler 28. Specifically, the internal temperature sensor 46 and the defrost temperature sensor 29 are each a temperature thermistor. The cooling duct 40 separates the storage chamber 34 from the cooler chamber 36, and also receives defrost water generated when frost adhering to the cooler 28 melts. A discharge pipe 48 is connected to the inclined portion 42 of the cooling duct 40, and is disposed behind the cooler 28 to discharge the defrost water. The discharge pipe 48 passes through the rear wall of the inner box 32 located behind the cooler chamber 36, and extends further downward.

[0029] Each device constituting the cooling device 18 (compressor 22, condenser 26, and cooler 28) is circulated and connected by refrigerant pipes to form a known refrigeration cycle (refrigeration circuit). The air inside the storage chamber 34 is drawn into the cooler chamber 36 from the intake port 42A by the internal fan 44. At this time, the internal air drawn in by the internal fan 44 hits the internal temperature sensor 46, thereby detecting the temperature inside the storage chamber 34, i.e., the internal temperature. The internal air drawn in by the internal fan 44 is cooled by the cooler 28 and discharged into the storage chamber 34 from the outlet port 42B. This cools the items stored in the storage chamber 34.

[0030] When the cooling device 18 is operated, the water vapor around the cooler 28 is cooled and solidified by the cooler 28, causing frost to form on the surface of the cooler 28. The frost that has formed on the cooler 28 melts when the freezer 10 starts a defrosting operation. The defrosting operation is performed by a heater defrost method in which the cooler 28 is heated by the defrost heater 27 to melt the frost that has formed on the cooler 28. The frost that has melted during the defrosting operation falls onto the inclined portion 42 of the cooling duct 40 and is discharged from the discharge pipe 48 to the outside of the storage body 12.

[0031] The doors 14 are attached so as to be able to open and close at the opening 12A of the storage body 12. As shown in Fig. 1, the doors 14 are provided in two pairs, one above the other, in a double door style, with two doors on the left and one on the right. A door packing (sealing member) 15 is attached to the peripheral edge of the rear surface (the surface on the inside of the storage body) of each door 14 so as to fit closely with the opening edge of the opening 12A of the storage body 12.

[0032] The machine room 16 is provided above the storage body 12, as shown in Figs. 1 and 2. As shown in Fig. 2, the machine room 16 houses a compressor 22 and a condenser 26. The compressor 22 is disposed at the rear of the machine room 16, whereas the condenser 26 is disposed at the front of the machine room 16 together with the condenser fan 24. The condenser fan 24 is attached to the rear of the condenser 26. A filter is provided at the front of the condenser 26 to prevent dust in the air from adhering to the condenser 26 and reducing the condensing capacity. If dust adheres to the filter and clogging occurs, sufficient heat exchange cannot be performed between the condenser 26 and the outside air even if the condenser fan 24 rotates, and the cooling efficiency may decrease. Therefore, a clogging temperature sensor (third sensor) 25 is attached to the piping of the condenser 26 via a holder in order to detect clogging of the filter. The clogging temperature sensor 25 is specifically a temperature thermistor, and can detect the temperature of the condenser 26 or the vicinity of the condenser 26. Since the temperature of the condenser 26 or the vicinity of the condenser 26 varies depending on the amount of dust adhering to the filter, it is possible to detect whether or not the filter is clogged based on the temperature detected by the clogging temperature sensor 25. In addition, the temperature detected by the clogging temperature sensor 25 while the cooling operation (operation of the compressor 22, etc.) is stopped is equivalent to the outside air temperature. Therefore, the clogging temperature sensor 25 is also capable of detecting the outside air temperature.

[0033] As shown in FIG. 1, an electrical equipment box 50 and an operation box 52 are housed in the machine room 16. An opening is provided in a part of the front of the machine room 16, and the front of the operation box 52 is exposed to the outside through the opening. A display screen 54 and a plurality of operation buttons 56 (an example of an operation unit) are provided on the front of the operation box 52. Information such as the internal temperature of the storage room 34 is displayed on the display screen 54. Each operation button 56 is a button for changing the settings of the freezer 10 (for example, the set temperature in the storage room 34, i.e., the internal set temperature) by the user. The electrical equipment box 50 houses a microcomputer in which a CPU, RAM, etc. are integrated into one chip, a control board equipped with a ROM, and the like.

[0034] The freezer 10 is provided with a control unit 20 that electrically controls various devices. The control unit 20 is configured with a control board in an electrical equipment box 50. The control board in the electrical equipment box 50 is electrically connected to the various devices. The control unit 20 controls the cooling operation and the defrosting operation, etc. (control of the compressor 22, the condenser fan 24, the internal fan 44, the defrost heater 27, etc.).

[0035] In detail, as shown in FIG. 3, the control unit 20 is electrically connected to the operation box 52, the compressor 22, the condenser fan 24, the internal fan 44, the clogging temperature sensor 25, the defrost temperature sensor 29, the defrost heater 27, and the internal temperature sensor 46. The control unit 20 performs a cooling operation by controlling the compressor 22, the condenser fan 24, and the internal fan 44 that constitute the refrigeration cycle. During the cooling operation, the control unit 20 operates the compressor 22, the condenser fan 24, and the internal fan 44, but stops the defrost heater 27 (see FIG. 4). The control unit 20 performs a defrost operation by controlling the defrost heater 27. During the defrost operation, the control unit 20 operates the defrost heater 27, but stops the compressor 22, the condenser fan 24, and the internal fan 44 (see FIG. 4). In detail, when the control unit 20 starts the defrosting operation, it stops the compressor 22, the condenser fan 24 and the inside fan 44, and operates the defrost heater 27, and waits until it stops the defrost heater 27 after a predetermined time has elapsed and ends the defrosting operation, in order to promote the removal of moisture adhering to the cooler 28. The waiting time from when the defrost heater 27 is stopped until the next cooling operation is started is called the draining time. The control unit 20 performs the cooling operation, the defrosting operation, etc., based on the operation performed on the operation button 56 of the operation box 52 and the temperatures detected by the clogging temperature sensor 25, the defrost temperature sensor 29 and the inside temperature sensor 46, respectively.

[0036] Specifically, the control unit 20 performs a cooling operation so that the internal temperature detected by the internal temperature sensor 46 becomes the internal temperature setting set in response to the operation of the operation button 56. This internal temperature setting can be changed as appropriate by the user operating the operation button 56, for example, even during the cooling operation. The control unit 20 performs the above-mentioned cooling operation for, for example, six hours, and then performs a defrosting operation until the temperature detected by the defrost temperature sensor 29 becomes the defrost end temperature. After performing the above-mentioned defrosting operation, the control unit 20 repeats the cycle of performing the cooling operation again for, for example, six hours, and then performing the defrosting operation again.

[0037] The control unit 20 can detect the opening and closing of the door 14 when the inside temperature detected by the inside temperature sensor 46 becomes equal to or higher than a predetermined door opening and closing detection temperature. This utilizes the fact that when the door 14 is opened and closed, outside air flows into the inside of the cabinet, causing the inside temperature to rise. Then, the control unit 20 can cancel the defrosting operation scheduled to be performed after the end of the cooling operation if the inside temperature detected by the inside temperature sensor 46 has never become equal to or higher than the door opening and closing detection temperature during the cooling operation. If the door 14 has never been opened or closed during the cooling operation, there is no inflow of outside air accompanying the opening and closing of the door 14, so frosting of the cooler 28 is sufficiently suppressed, and it can be said that even if the defrosting operation is canceled, the cooling performance is unlikely to decrease due to frosting. If the defrosting operation is canceled, the rise in the inside temperature accompanying the execution of the defrosting operation can be avoided, so the amount of power consumption required for the cooling operation can be reduced. When the control unit 20 cancels the defrosting operation as described above, the control unit 20 starts the next cooling operation following the end of the previous cooling operation. When the control unit 20 cancels the defrosting operation twice in succession, the control unit 20 always executes the next defrosting operation. In other words, when the control unit 20 cancels the defrosting operation twice in succession and executes the cooling operation three times (for example, for 18 hours) in succession, the control unit 20 executes the next scheduled defrosting operation without canceling it even if the door 14 has not been opened or closed during the three cooling operations. As a result, even if a certain amount of frost forms on the cooler 28 as a result of the cooling operation being continued for a long period of time, the control unit 20 can appropriately defrost the cooler 28 by executing the defrosting operation. In addition, when the temperature detected by the clogging temperature sensor 25 reaches a predetermined clogging detection temperature, the control unit 20 can display a message on the display screen 54 urging the user to clean the filter.

[0038] However, if the heating by the defrost heater 27 during defrosting operation is excessive compared to the amount of frost on the cooler 28, the power consumption for energizing the defrost heater 27 increases and the temperature inside the storage rises, which not only increases the power consumption during cooling operation but also deteriorates the quality of the stored items contained in the storage chamber 34. Conventionally, the defrost setting temperature for determining the end of defrosting was varied based on the outside air temperature detected by the outside air temperature sensor, so there was a risk that an appropriate defrosting operation according to the actual amount of frost could not be performed depending on conditions such as the insulation performance of the storage body 12 and the number of times the door 14 was opened and closed.

[0039] Therefore, the control unit 20 according to this embodiment changes the defrost end temperature based on whether or not at least one selection condition selected from the following first condition, second condition, third condition, and fourth condition is satisfied. The first condition among the four conditions is that the number of times that the inside temperature detected by the inside temperature sensor 46 during the cooling operation becomes equal to or higher than the door opening / closing detection temperature becomes equal to or lower than a preset reference number of times (see FIG. 4). The second condition is that the inside temperature setting during the cooling operation becomes equal to or higher than a preset reference temperature setting (see FIG. 5). The third condition is that the difference between the inside temperature detected by the inside temperature sensor 46 during the cooling operation and the inside temperature setting becomes equal to or lower than a preset reference value (see FIG. 6). The fourth condition is that the temperature detected by the defrost temperature sensor 29 during the cooling operation becomes equal to or higher than a preset reference defrost temperature (see FIG. 7). When at least one selection condition selected from these four conditions is satisfied, the control unit 20 performs the defrosting operation until the temperature detected by the defrost temperature sensor 29 becomes a first defrosting end temperature (e.g., 3°C), which is the defrosting end temperature. On the other hand, when at least one selection condition selected from the above-mentioned four conditions is not satisfied, the control unit 20 performs the defrosting operation until the temperature detected by the defrost temperature sensor 29 becomes a second defrosting end temperature (e.g., 20°C), which is a defrosting end temperature higher than the first defrosting end temperature.

[0040] In the above-mentioned first condition, the number of openings and closings of the door 14 detected based on the inside temperature detected by the inside temperature sensor 46 during the cooling operation performed before the defrosting operation is used as an index, and if the number of openings and closings of the door 14 is equal to or less than a reference number (for example, once), the inflow of air with high humidity outside the compartment into the compartment is suppressed, so that it is estimated that the amount of frost on the cooler 28 is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the first condition is met, it is possible to prevent the heating by the defrost heater 27 from being excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. On the other hand, if the first condition is not met, it is estimated that the amount of frost on the cooler 28 is large because more air with high humidity outside the compartment flows into the compartment than when the first condition is met, so that the defrosting operation is performed until the second defrosting end temperature, which is higher than the first defrosting end temperature, so that the heating by the defrost heater 27 is sufficient to match the amount of frost on the cooler 28. This allows the frost adhering to the cooler 28 to be sufficiently removed, thereby preventing the cooler 28 from freezing and preventing a decrease in the cooling performance of the refrigeration cycle due to residual frost.

[0041] In the second condition described above, the set temperature in the refrigerator during the cooling operation performed before the defrosting operation is used as an index, and if the set temperature in the refrigerator is equal to or higher than the reference set temperature (for example, -22°C), the refrigeration cycle operates at a low temperature, so the temperature of the cooler 28 does not drop so much and it is estimated that the amount of frost is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the second condition is met, it is possible to prevent the heating by the defrost heater 27 from being excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. On the other hand, if the second condition is not met, it is estimated that the refrigeration cycle operates at a high temperature compared to when the second condition is met, the temperature of the cooler 28 is lower, and the amount of frost on the cooler 28 is large. Therefore, if the defrosting operation is performed until the second defrosting end temperature, which is higher than the first defrosting end temperature, the heating by the defrost heater 27 is sufficient to match the amount of frost on the cooler 28. This allows the frost adhering to the cooler 28 to be sufficiently removed, thereby preventing the cooler 28 from freezing and preventing a decrease in the cooling performance of the refrigeration cycle due to residual frost.

[0042] In the above-mentioned third condition, the difference between the inside temperature during the cooling operation performed before the defrosting operation and the set inside temperature is used as an index, and if the difference is equal to or less than a reference value (for example, 1K (Kelvin)), it can be said that the heat exchange efficiency of the refrigeration cycle has not decreased significantly due to frosting of the cooler 28, and therefore it is estimated that the amount of frosting of the cooler 28 is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the third condition is met, it is possible to prevent the heating by the defrost heater 27 from becoming excessive compared to the amount of frosting of the cooler 28, and it is possible to reduce the amount of power consumption. On the other hand, if the third condition is not met, it is estimated that the heat exchange efficiency of the refrigeration cycle has decreased due to frosting of the cooler 28 compared to when the third condition is met, and therefore the amount of frosting of the cooler 28 is large. Therefore, if the defrosting operation is performed until the second defrosting end temperature, which is higher than the first defrosting end temperature, the heating by the defrost heater 27 will be sufficient to match the amount of frosting of the cooler 28. This allows the frost adhering to the cooler 28 to be sufficiently removed, thereby preventing the cooler 28 from freezing and preventing a decrease in the cooling performance of the refrigeration cycle due to residual frost.

[0043] In the above-mentioned fourth condition, the temperature of the cooler 28 or its vicinity during the cooling operation performed before the defrost operation is used as an index, and if the temperature is equal to or higher than the reference defrost temperature (for example, -28°C), it is estimated that the temperature of the cooler 28 is not so low, and therefore the amount of frost on the cooler 28 is small. Therefore, if the defrost operation is performed until the first defrost end temperature, which is lower than the second defrost end temperature, is reached when the fourth condition is met, it is possible to prevent the heating by the defrost heater 27 from being excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. On the other hand, if the fourth condition is not met, it is estimated that the temperature of the cooler 28 is lower than when the fourth condition is met, and therefore the amount of frost on the cooler 28 is large. Therefore, if the defrost operation is performed until the second defrost end temperature, which is higher than the first defrost end temperature, the heating by the defrost heater 27 is sufficient to match the amount of frost on the cooler 28. This allows the frost adhering to the cooler 28 to be sufficiently removed, thereby preventing the cooler 28 from freezing and preventing a decrease in the cooling performance of the refrigeration cycle due to residual frost.

[0044] As described above, by varying the defrost end temperature based on whether or not at least one selection condition selected from the first condition to the fourth condition is satisfied, appropriate defrosting operation can be performed according to the amount of frost on cooler 28, thereby reducing power consumption and sufficiently removing frost that has adhered to cooler 28.

[0045] Next, the control when the first condition, the second condition, the third condition, and the fourth condition are selected individually will be described with reference to Figs. 4 to 7. In Figs. 4 to 7, the operating state of the compressor 22, the condenser fan 24, the interior fan 44, and the defrost heater 27 is indicated as ON, and the stopped state is indicated as OFF. In Figs. 4 to 7, the transition of the temperature detected by the interior temperature sensor 46 and the defrost temperature sensor 29 is indicated, and the first defrost detection temperature and the second defrost detection temperature are also indicated for the defrost temperature sensor 29. In Figs. 5 and 6, the transition of the interior set temperature is indicated. In Fig. 6, the difference between the interior temperature detected by the interior temperature sensor 46 and the interior set temperature is indicated as "temperature difference", and the reference value is also indicated. In Figs. 4 to 7, the draining time is indicated as "draining".

[0046] First, the control when the first condition is set as the selection condition will be described in detail with reference to FIG. 4. First, in the first condition according to the present embodiment, the index is the number of times that the inside temperature detected by the inside temperature sensor 46 becomes equal to or higher than the door opening / closing detection temperature during a set time during which the cooling operation performed immediately before the defrosting operation is performed, that is, the frequency of opening and closing the door 14. Specifically, as shown in FIG. 4, the control unit 20 divides the time during which the cooling operation is performed (e.g., 6 hours) into a plurality of (e.g., 24) periods, and detects the number of times that the inside temperature detected by the inside temperature sensor 46 becomes equal to or higher than the door opening / closing detection temperature during each divided set time period (e.g., 15 minutes each). The control unit 20 counts the number of times that the door 14 is opened and closed based on the inside temperature detected by the inside temperature sensor 46 during the divided set time period of 15 minutes, and compares the counted number of times with a reference number of times. The control unit 20 repeats the operation (routine) of counting the number of times the door 14 is opened and closed and comparing it with the reference number 24 times during cooling operation, and determines which defrost detection temperature to set based on whether or not the number of times the door 14 is opened and closed exceeds the reference number even once. Note that the set time may always be the elapsed time since the door 14 was opened once, and the first opening may be counted as 1st.

[0047] For example, the first cooling operation (left side of FIG. 4) shown in FIG. 4 includes a case where the door 14 is opened and closed twice within the set time, which is more than the reference number of times, 1 time. In this case, the control unit 20 determines that the first condition is not satisfied, and in the first defrosting operation (left side of FIG. 4) performed following the first cooling operation, the control unit 20 causes the defrost heater 27 to heat the cooler 28 until the temperature (defrosting temperature) detected by the defrost temperature sensor 29 reaches 20° C., which is the second defrosting end temperature. In FIG. 4, the defrosting operation in which the defrosting end temperature is the second defrosting end temperature is represented as a “normal defrosting operation”, and the same is true in the following FIGS. 5 to 8. On the other hand, the second cooling operation (right side of FIG. 4) shown in FIG. 4 does not include a case where the door 14 is opened and closed twice or more within the set time, and only includes a case where the door 14 is opened and closed once, which is the same as the reference number of times. In this case, the control unit 20 determines that the first condition is satisfied, and in the second defrosting operation (on the right side of FIG. 4) performed following the second cooling operation, the defrost heater 27 heats the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 3° C., which is the first defrost end temperature. In FIG. 4, the defrosting operation in which the defrost end temperature is the first defrost end temperature is indicated as a “simple defrosting operation”, and the same applies to the following FIGS. 5 to 8. The time required for the simple defrosting operation when the first condition is satisfied and the time during which the defrost heater 27 is energized in the simple defrosting operation are both shorter than the times in the normal defrosting operation when the first condition is not satisfied. The maximum temperature of the inside temperature that rises with the simple defrosting operation when the first condition is satisfied is lower than the maximum temperature of the inside temperature that rises with the normal defrosting operation when the first condition is not satisfied.

[0048] The control when the second condition is set as the selection condition will be described in detail with reference to FIG. 5. In the second condition according to the present embodiment, the in-compartment set temperature during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 5, the control unit 20 detects the in-compartment set temperature set in response to the operation of the operation button 56 while the cooling operation is being performed, and compares the in-compartment set temperature with the reference set temperature. For example, the operation time of the first cooling operation (left side of FIG. 5) shown in FIG. 5 partially includes a time during which the in-compartment set temperature is set lower than the reference set temperature of -22°C. In this case, the control unit 20 determines that the second condition is not satisfied, and in the first defrosting operation (left side of FIG. 5) performed following the first cooling operation, the control unit 20 causes the defrost heater 27 to heat the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 20°C, which is the second defrost end temperature (normal defrosting operation). On the other hand, in the second cooling operation (right side of FIG. 5) shown in FIG. 5, the internal set temperature continues to be higher than the reference set temperature of -22°C, and the internal set temperature never becomes lower than -22°C. In this case, the control unit 20 determines that the second condition is satisfied, and in the second defrosting operation (right side of FIG. 5) performed following the second cooling operation, the control unit 20 causes the defrost heater 27 to heat the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 3°C, which is the first defrost end temperature (simple defrosting operation). The time required for the simple defrosting operation when the second condition is satisfied and the time for which the defrost heater 27 is energized in the simple defrosting operation are both shorter than the times in the normal defrosting operation when the second condition is not satisfied. Furthermore, as in the case of the first condition (see FIG. 4), the maximum internal temperature that rises in association with the simple defrost operation when the second condition is satisfied is lower than the maximum internal temperature that rises in association with the normal defrost operation when the second condition is not satisfied.

[0049] The control when the third condition is set as the selection condition will be described in detail with reference to FIG. 6. In the third condition according to the present embodiment, the difference between the inside temperature detected by the inside temperature sensor 46 at the set time immediately before the defrosting operation and the set inside temperature is used as an index. Specifically, as shown in FIG. 6, the control unit 20 sets the set time to 2 hours immediately before the defrosting operation is started (2 hours from 4 hours after the cooling operation is started until the defrosting operation is started), detects the inside temperature detected by the inside temperature sensor 46 and the set inside temperature set in response to the operation of the operation button 56 at the set time, calculates the temperature difference between them, and compares the calculated temperature difference with a reference value. For example, in the set time for the first cooling operation shown in FIG. 6 (left side of FIG. 6), the temperature difference is always higher than the reference value of 1K and never becomes lower than 1K. In this case, the control unit 20 determines that the third condition is not satisfied, and in the first defrosting operation (left side of FIG. 6) performed following the first cooling operation, the defrost heater 27 heats the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 20°C, which is the second defrost end temperature (normal defrosting operation). Meanwhile, the set time in the second cooling operation (right side of FIG. 6) shown in FIG. 6 includes a timing at which the temperature difference becomes lower than the reference value of 1K. This is because the temperature difference between the inside temperature and the inside temperature setting becomes smaller as the inside temperature setting is changed to be higher while the normal defrosting operation is being performed. In this case, the control unit 20 determines that the third condition is satisfied, and in the second defrosting operation (on the right side of FIG. 6) performed following the second cooling operation, the defrost heater 27 heats the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 3°C, which is the first defrost end temperature (simple defrosting operation). The time required for the simple defrosting operation when the third condition is satisfied and the time during which the defrost heater 27 is energized in the simple defrosting operation are both shorter than the times in the normal defrosting operation when the third condition is not satisfied. The maximum temperature of the inside temperature that rises as the simple defrosting operation is performed when the third condition is satisfied is lower than the maximum temperature of the inside temperature that rises as the normal defrosting operation is performed when the third condition is not satisfied.

[0050] The control when the fourth condition is set as the selection condition will be described in detail with reference to FIG. 7. In the fourth condition according to the present embodiment, the temperature detected by the defrost temperature sensor 29 in the set time immediately before the defrost operation is set as an index. Specifically, as shown in FIG. 7, the control unit 20 sets the set time to 15 minutes immediately before the defrost operation is started (15 minutes from 5 hours and 45 minutes after the cooling operation is started until the defrost operation is started), and detects the temperature detected by the defrost temperature sensor 29 in the set time and compares the temperature with the reference defrost temperature. For example, the set time in the first cooling operation (left side of FIG. 7) shown in FIG. 7 includes a timing when the temperature detected by the defrost temperature sensor 29 becomes lower than the reference defrost temperature of −28° C. In this case, the control unit 20 determines that the fourth condition is not satisfied, and in the first defrosting operation (left side of FIG. 7) performed following the first cooling operation, the defrost heater 27 heats the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 20° C., which is the second defrost end temperature (normal defrosting operation). On the other hand, in the set time in the second cooling operation (right side of FIG. 7) shown in FIG. 7, the temperature detected by the defrost temperature sensor 29 continues to be higher than −28° C., which is the reference defrost temperature, and never becomes lower than −28° C. In this case, the control unit 20 determines that the fourth condition is satisfied, and in the second defrosting operation (right side of FIG. 7) performed following the second cooling operation, the defrost heater 27 heats the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 3° C., which is the first defrost end temperature (simplified defrosting operation). The time required for simple defrost operation when the fourth condition is satisfied and the time for which the defrost heater 27 is energized in the simple defrost operation are both shorter than the times in normal defrost operation when the fourth condition is not satisfied. Also, as in the case of the first condition (see FIG. 4), the maximum temperature inside the refrigerator that rises as the simple defrost operation is performed when the fourth condition is satisfied is lower than the maximum temperature inside the refrigerator that rises as the normal defrost operation is performed when the fourth condition is not satisfied.

[0051] Next, the control in the case where all of the first condition, the second condition, the third condition, and the fourth condition are set as the selection conditions will be described in sequence with reference to FIG. 8. The notations in FIG. 8 are the same as those in FIG. 4 to FIG. 7. As shown in FIG. 8, the control unit 20 selects different defrost end temperatures based on whether all of the same first condition, second condition, third condition, and fourth condition as above are satisfied. For example, the first cooling operation (left side of FIG. 8) shown in FIG. 8 includes a case where the number of times the door 14 is opened and closed within the set time is two, which is more than the reference number of times of one, and the state where the internal temperature setting is continuously set lower than the reference temperature setting of -22°C and has never been set higher than -22°C, and further, the temperature difference between the internal temperature and the internal temperature setting is always higher than the reference value of 1K and has never been lower than 1K, and includes a timing where the temperature detected by the defrost temperature sensor 29 is lower than the reference defrost temperature of -28°C. In this case, the control unit 20 determines that all of the first, second, third and fourth conditions are not satisfied, and in the first defrosting operation (left side of FIG. 8) performed following the first cooling operation, the control unit 20 causes the defrost heater 27 to heat the cooler 28 until the temperature (defrosting temperature) detected by the defrost temperature sensor 29 reaches 20° C., which is the second defrost end temperature (normal defrosting operation). Note that the control unit 20 performs the normal defrosting operation described above not only when all of the first, second, third and fourth conditions are not satisfied as described above, but also when any one, two or three of the first, second, third and fourth conditions are not satisfied (when any three, two or one of the first, second, third and fourth conditions are satisfied).

[0052] On the other hand, the second cooling operation shown in Fig. 8 (on the right side of Fig. 8) does not include a case where the door 14 is opened and closed twice or more within the set time, but only includes a case where the door 14 is opened and closed once, which is the same as the reference number of times, and the internal temperature setting continues to be set higher than the reference temperature setting of -22°C and is never set lower than -22°C, and there is a time when the temperature difference between the internal temperature and the internal temperature setting is lower than the reference value of 1K, and the temperature detected by the defrost temperature sensor 29 continues to be higher than the reference defrost temperature setting of -28°C and never falls below -28°C. The internal temperature setting is changed to be higher than the reference temperature setting of -22°C during the first defrost operation (normal defrost operation). In this case, the control unit 20 determines that all of the first, second, third and fourth conditions are satisfied, and in the second defrost operation (right side of Figure 8) performed following the second cooling operation, the control unit 20 causes the defrost heater 27 to heat the cooler 28 until the temperature detected by the defrost temperature sensor 29 reaches 3°C, which is the first defrost end temperature (simple defrost operation).

[0053] In this way, when all of the first, second, third and fourth conditions are satisfied, it can be said that there is a very high probability that the amount of frost on the cooler 28 is small. Therefore, if the above-mentioned simple defrosting operation is performed only when all of the first, second, third and fourth conditions are satisfied, there is a very high probability that the heating by the defrost heater 27 will be prevented from becoming excessive compared to the amount of frost on the cooler 28, and power consumption can be reduced. In other words, there is a high probability that the simple defrosting operation will be avoided even when the amount of frost is large, so that it is less likely that the defrosting will be insufficient and the cooler 28 will freeze, or that the cooling performance of the refrigeration cycle will be reduced. In addition, the time required for the simple defrosting operation when all of the first, second, third and fourth conditions are satisfied and the time during which the defrost heater 27 is energized in the simple defrosting operation are both shorter than the times in the normal defrosting operation when at least one (including all) of the first, second, third and fourth conditions are not satisfied. Furthermore, the maximum temperature inside the cabinet that rises in conjunction with the simple defrosting operation when all of the first condition, the second condition, the third condition and the fourth condition are satisfied is lower than the maximum temperature inside the cabinet that rises in conjunction with the normal defrosting operation when at least one of the first condition, the second condition, the third condition and the fourth condition is not satisfied.

[0054] It is not necessary to set all of the first, second, third and fourth conditions as selection conditions, but it is also possible to set any three or two of the first, second, third and fourth conditions as selection conditions, for example.

[0055] As described above, the freezer (cooling storage) 10 of this embodiment includes the storage body 12 having the opening 12A, the door 14 for opening and closing the opening 12A, the internal temperature sensor 46 for detecting the internal temperature, the cooler (evaporator) 28 constituting a refrigeration cycle, the defrost heater (heating unit) 27 for heating the cooler 28, the defrost temperature sensor 29 for detecting the temperature of the cooler 28 or near the cooler 28, and the control unit 20 for controlling the refrigeration cycle to perform a cooling operation so that the internal temperature detected by the internal temperature sensor 46 becomes the internal set temperature, and for controlling the defrost heater 27 to perform a defrost operation until the temperature detected by the defrost temperature sensor 29 becomes the defrost end temperature. The control unit 20 detects the opening and closing of the door 14 when the internal temperature detected by the internal temperature sensor 46 becomes equal to or higher than a predetermined door opening / closing detection temperature. When at least one selection condition is satisfied from among a first condition that the number of times that the inside temperature detected by the inside temperature sensor 46 during cooling operation becomes equal to or higher than the door opening / closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during cooling operation becomes equal to or higher than a reference set temperature, a third condition that the difference between the inside temperature detected by the inside temperature sensor 46 during cooling operation and the inside temperature set during cooling operation becomes equal to or lower than a reference value, and a fourth condition that the temperature detected by the defrost temperature sensor 29 during cooling operation becomes equal to or higher than a reference defrost temperature, the defrost operation is performed until the temperature detected by the defrost temperature sensor 29 becomes a first defrost end temperature, which is a defrost end temperature, and when the selection condition is not satisfied, the defrost operation is performed until the temperature detected by the defrost temperature sensor 29 becomes a second defrost end temperature, which is a defrost end temperature higher than the first defrost end temperature.

[0056] When the cooling operation is performed by the control unit 20, the refrigeration cycle is controlled so that the air inside the storage compartment is cooled by the cooler 28, and the temperature inside the storage compartment detected by the temperature sensor 46 becomes the set temperature inside the storage compartment. When the defrost operation is performed by the control unit 20, the defrost heater 27 is controlled so that the cooler 28 is heated until the temperature detected by the defrost temperature sensor 29 becomes the defrost end temperature. Here, if the heating by the defrost heater 27 is excessive compared to the amount of frost on the cooler 28, problems such as an increase in the amount of power consumed by the defrost heater 27 and an increase in the temperature inside the storage compartment cause problems such as an increase in the amount of power consumed in the cooling operation. Conventionally, the defrost set temperature for determining the end of the defrost was varied based on the outside air temperature detected by the outside air temperature sensor, so that there was a risk that an appropriate defrost operation according to the actual amount of frost could not be performed depending on conditions such as the insulation performance of the storage compartment body 12 and the number of times the door 14 was opened and closed.

[0057] In this regard, when at least one of the selection conditions selected from the first condition, the second condition, the third condition, and the fourth condition is satisfied, the control unit 20 performs the defrosting operation until the temperature detected by the defrosting temperature sensor 29 becomes the first defrosting end temperature, and when the selection conditions are not satisfied, the control unit 20 performs the defrosting operation until the temperature detected by the defrosting temperature sensor 29 becomes the second defrosting end temperature higher than the first defrosting end temperature. In detail, the first condition uses the number of opening and closing of the door 14 during the cooling operation as an index, and if the number of opening and closing of the door 14 is equal to or less than a reference number, the inflow of air with high humidity outside the refrigerator into the refrigerator is suppressed, so that it is estimated that the amount of frost on the cooler 28 is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is satisfied when the first condition is satisfied, it is possible to prevent the heating by the defrosting heater 27 from becoming excessive compared to the amount of frost on the cooler 28, and to reduce the amount of power consumption. In the second condition, the in-compartment temperature set before the defrosting operation is used as an index, and if the in-compartment temperature set is equal to or higher than the reference set temperature, the refrigeration cycle can be operated at a low temperature, so that the temperature of the cooler 28 does not drop too much and it is estimated that the amount of frost is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the second condition is met, it is possible to prevent the heating by the defrost heater 27 from becoming excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. In the third condition, the difference between the in-compartment temperature before the defrosting operation and the in-compartment temperature set is used as an index, and if the difference is equal to or lower than the reference value, it is possible to say that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frosting on the cooler 28, and it is therefore estimated that the amount of frost on the cooler 28 is small. Therefore, if the defrosting operation is performed until the first defrosting end temperature, which is lower than the second defrosting end temperature, is reached when the third condition is met, it is possible to prevent the heating by the defrost heater 27 from becoming excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. The fourth condition uses the temperature of cooler 28 or its vicinity before defrosting operation as an index, and if that temperature is equal to or higher than the reference defrost temperature, it is estimated that the temperature of cooler 28 has not dropped significantly, and therefore the amount of frost on cooler 28 is small.Therefore, if the defrosting operation is performed until the first defrost end temperature, which is lower than the second defrost end temperature, is reached when the fourth condition is satisfied, it is possible to prevent the heating by the defrost heater 27 from becoming excessive compared to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption. As described above, if the defrost end temperature is varied based on whether or not at least one selection condition selected from the first condition, the second condition, the third condition, and the fourth condition is satisfied, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler 28, and it is possible to reduce the amount of power consumption.

[0058] In addition, when performing the defrosting operation, the control unit 20 selects whether to use the first defrosting end temperature or the second defrosting end temperature as the defrosting end temperature based on whether at least all of the first condition, the second condition, the third condition, and the fourth condition are satisfied. When the first condition, the second condition, the third condition, and the fourth condition are all satisfied, it can be said that there is an extremely high probability that the amount of frost formed on the cooler 28 is small. Therefore, if the control unit 20 performs the defrosting operation until the temperature detected by the defrosting temperature sensor 29 becomes the first defrosting end temperature, which is lower than the second defrosting end temperature, only when the first condition, the second condition, the third condition, and the fourth condition are all satisfied, there is an extremely high probability that the heating by the defrost heater 27 is prevented from becoming excessive compared to the amount of frost formed on the cooler 28, and the amount of power consumption can be reduced. In other words, even if the amount of frost is large, the control unit 20 is more likely to avoid performing defrosting operation until the temperature detected by the defrost temperature sensor 29 reaches the first defrost end temperature, making it less likely that defrosting will be insufficient, causing the cooler 28 to freeze, or that the cooling performance of the refrigeration cycle will decrease.

[0059] In addition, the control unit 20 selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the first condition is satisfied when performing the defrosting operation, and the first condition is that the number of times that the inside temperature detected by the inside temperature sensor 46 becomes equal to or higher than the door opening / closing detection temperature during a set time during the cooling operation is equal to or less than a reference number. In the first condition, the frequency of opening and closing of the door 14 during the cooling operation is used as an index, and if the frequency of opening and closing of the door 14 is low, the inflow of high humidity air from outside the refrigerator into the refrigerator is suppressed, so it is estimated that the amount of frost on the cooler 28 is small. Therefore, by making the defrost end temperature different based on whether or not the first condition is satisfied, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler 28. Furthermore, compared to the conventional method in which defrosting operation was performed until the temperature detected by defrost temperature sensor 29 reached the second defrost end temperature if door 14 was opened or closed even once during cooling operation, power consumption can be reduced more suitably by varying the defrost end temperature based on whether or not the first condition, which is based on the frequency of opening and closing of door 14, is satisfied. Also, because opening and closing of door 14 is detected using internal temperature sensor 46 that detects the internal temperature, there is no need to install a switch compared to the case in which such a switch is installed on door 14 to detect opening and closing.

[0060] In addition, the control unit 20 selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the third condition is satisfied when performing the defrosting operation, and the third condition is that the difference between the inside temperature detected by the inside temperature sensor 46 and the inside temperature set at least in the set time immediately before the defrosting operation is equal to or less than a reference value. In the third condition, the difference between the inside temperature and the inside temperature set in the set time immediately before the defrosting operation is used as an index. As a result, whether or not the heat exchange efficiency of the refrigeration cycle is reduced due to frosting of the cooler 28 at the stage immediately before the defrosting operation is accurately reflected in the difference between the inside temperature and the inside temperature set. Therefore, if the defrost end temperature is made different based on whether or not the third condition is satisfied, an appropriate defrosting operation can be performed according to the amount of frosting of the cooler 28.

[0061] In addition, the control unit 20 selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the fourth condition is satisfied when performing the defrosting operation, and the fourth condition is that the temperature detected by the defrost temperature sensor 29 at the set time immediately before the defrosting operation is equal to or higher than the reference defrost temperature. In the fourth condition, the temperature of the cooler 28 or its vicinity at the set time immediately before the defrosting operation is used as an index. As a result, whether or not the amount of frost on the cooler 28 is large due to a temperature drop of the cooler 28 at the stage immediately before the defrosting operation is accurately reflected in the temperature of the cooler 28 or its vicinity. Therefore, if the defrost end temperature is made different based on whether or not the fourth condition is satisfied, an appropriate defrosting operation can be performed according to the amount of frost on the cooler 28.

[0062] <Embodiment 2> A second embodiment will be described with reference to Fig. 9. In this second embodiment, the contents of the first condition are changed. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 9 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0063] In the first condition according to the present embodiment, the index is the total number of times that the inside temperature detected by the inside temperature sensor during the cooling operation performed immediately before the defrosting operation becomes equal to or higher than the door opening / closing detection temperature, that is, the accumulated number of times. Specifically, as shown in FIG. 9, the control unit counts and accumulates the number of times that the door is opened and closed based on the inside temperature detected by the inside temperature sensor from the start to the end of the cooling operation, and compares the accumulated number with a reference number (e.g., 2 times). For example, the accumulated number of times that the door is opened and closed during the first cooling operation (left side of FIG. 9) shown in FIG. 9 is 3 times, which is more than the reference number of 2 times. In this case, the control unit determines that the first condition is not satisfied, and in the first defrosting operation (left side of FIG. 9) performed following the first cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature (defrost temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrosting operation). On the other hand, the cumulative number of times the door is opened and closed during the second cooling operation (right side of FIG. 9) shown in FIG. 9 is 1, which is less than the reference number of times, 2. In this case, the control unit determines that the first condition is satisfied, and in the second defrosting operation (right side of FIG. 9) performed following the second cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature detected by the defrost temperature sensor reaches 3°C, which is the first defrost end temperature (simple defrosting operation). Note that, if the cumulative number of times the door is opened and closed during the cooling operation is 2, which is the same as the reference number, the control unit determines that the first condition is satisfied and performs the simple defrosting operation. Even if control is performed using such a first condition as a selection condition, the same action and effect as those of the above-mentioned embodiment 1 can be obtained.

[0064] <Embodiment 3> A third embodiment will be described with reference to Fig. 10. In this third embodiment, the content of the fourth condition is changed from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 10 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0065] In the fourth condition according to the present embodiment, the temperature detected by the defrost temperature sensor during the cooling operation performed immediately before the defrost operation is used as an index. Specifically, as shown in FIG. 10, the control unit repeatedly detects the temperature detected by the defrost temperature sensor from the start to the end of the cooling operation, and compares the temperature with the reference defrost temperature. For example, during the first cooling operation (left side of FIG. 10) shown in FIG. 10, the temperature detected by the defrost temperature sensor continues to be lower than the reference defrost temperature of -28°C, and never becomes higher than -28°C. In this case, the control unit determines that the fourth condition is not satisfied, and in the first defrost operation (left side of FIG. 10) performed following the first cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrost operation). In addition, even if there is a time when the temperature detected by the defrost temperature sensor is higher than the reference defrost temperature of -28°C during the period from the start to the end of the cooling operation, if there is a time when the temperature is lower than -28°C even once, the control unit determines that the fourth condition is not satisfied and performs a normal defrost operation. On the other hand, in the second cooling operation (right side of FIG. 10) shown in FIG. 10, the temperature detected by the defrost temperature sensor continues to be higher than the reference defrost temperature of -28°C and never becomes lower than -28°C. In this case, the control unit determines that the fourth condition is satisfied, and in the second defrost operation (right side of FIG. 10) performed following the second cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature detected by the defrost temperature sensor reaches the first defrost end temperature of 3°C (simple defrost operation). Even if control is performed using such a fourth condition as a selection condition, the same actions and effects as those of the above-mentioned embodiment 1 can be obtained.

[0066] <Embodiment 4> A fourth embodiment will be described with reference to Fig. 11. In this fourth embodiment, a second condition is added to the selection conditions in the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 11 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0067] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a second condition is satisfied in addition to the selection condition described in the first embodiment. In the second condition, the index is the accumulated time during which the inside temperature detected by the inside temperature sensor during the cooling operation performed immediately before the defrosting operation is equal to or lower than the inside temperature set point. Specifically, as shown in FIG. 11, the control unit accumulates the time during which the inside temperature detected by the inside temperature sensor is equal to or lower than the inside temperature set point from the start to the end of the cooling operation, and compares the accumulated time with a reference accumulated time (e.g., 2 hours), and if the accumulated time is equal to or higher than the reference accumulated time, it is determined that the second condition is satisfied. If the accumulated time during which the inside temperature is equal to or lower than the inside temperature set point is equal to or higher than the reference accumulated time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation of the cooler, and therefore it is estimated that the amount of frost formation of the cooler is small. Conversely, if the accumulated time during which the internal temperature is below the internal set temperature is shorter than the standard accumulated time, it is estimated that the cooling performance of the refrigeration cycle is not being properly performed, and that the heat exchange efficiency of the refrigeration cycle has decreased due to frost formation on the cooler, resulting in a large amount of frost formation on the cooler.

[0068] For example, the accumulated time during which the inside temperature during the first cooling operation (left side of FIG. 11) shown in FIG. 11 is equal to or lower than the inside temperature set value is 1.8 hours, which is shorter than the reference accumulated time of 2 hours. In this case, the control unit determines that the second condition is not satisfied, and in the first defrosting operation (left side of FIG. 11) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrosting operation). On the other hand, the accumulated time during which the inside temperature during the second cooling operation (right side of FIG. 11) shown in FIG. 11 is equal to or lower than the inside temperature set value is 2.5 hours, which is longer than the reference accumulated time of 2 hours. In this case, if the control unit determines that the second condition is satisfied and also satisfies the selection condition described in the first embodiment, in the second defrosting operation (on the right side of FIG. 11) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3°C, which is the first defrost end temperature (simple defrosting operation). Note that even if the second condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. Also, in the two cooling operations shown in FIG. 11, there is a timing at which the compressor and the condenser fan are temporarily stopped. This is because, when it is detected that the inside temperature detected by the inside temperature sensor is equal to or lower than the inside temperature setting, the control unit temporarily stops the compressor and the condenser fan, and when it is detected that the inside temperature detected by the inside temperature sensor is equal to or higher than the inside temperature setting, the control unit controls the compressor and the condenser fan to resume operation. By varying the defrost end temperature based on whether or not such a second condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost formed on the cooler.

[0069] As described above, according to this embodiment, in addition to the selection condition, if the control unit satisfies the second condition that the accumulated time during which the inside temperature detected by the inside temperature sensor during the cooling operation is equal to or less than the inside temperature set temperature is equal to or more than the reference accumulated time, the control unit performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the first defrosting end temperature, and if the selection condition and the second condition are not satisfied, the control unit performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the second defrosting end temperature. In the second condition, the accumulated time during which the inside temperature is equal to or less than the inside temperature set temperature is used as an index, and if the accumulated time is equal to or more than the reference accumulated time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation of the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrosting end temperature is made different based on whether or not the second condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frost formation on the cooler can be performed.

[0070] <Embodiment 5> A fifth embodiment will be described with reference to Fig. 12. In this fifth embodiment, a third condition is added to the selection conditions in the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 12 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0071] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a third condition is satisfied in addition to the selection conditions described in the first embodiment. In the third condition, the number of times that the compressor constituting the refrigeration cycle is stopped during a set time immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 12, the control unit sets the set time to two hours immediately before the defrosting operation is started (two hours from the start of the cooling operation until the start of the defrosting operation), counts the number of times that the compressor is stopped during the set time, compares the number of times with a reference number (for example, once), and determines that the third condition is satisfied if the number of times is equal to or greater than the reference number. The control unit can count the number of times that the compressor is stopped based on the input voltage to the compressor, etc. The control unit temporarily stops the compressor and the condenser fan when it is detected that the inside temperature detected by the inside temperature sensor is equal to or lower than the inside temperature set, and then controls the compressor and the condenser fan to resume operation when it is detected that the inside temperature detected by the inside temperature sensor is equal to or higher than the inside temperature set. Here, if the number of times the compressor is stopped during cooling operation is equal to or greater than the reference number, it can be said that the cooling performance of the refrigeration cycle is being properly exerted, the interior of the refrigerator is being properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the number of times the compressor is stopped during cooling operation is less than the reference number, it is estimated that the cooling performance of the refrigeration cycle is not being properly exerted, the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, and the amount of frost formation on the cooler is large.

[0072] For example, in the set time of the first cooling operation (left side of FIG. 12) shown in FIG. 12, the compressor is not stopped even once, and the number of times the compressor is stopped is set to 0, which is less than the reference number of times, 1. In this case, the control unit determines that the third condition is not satisfied, and regardless of whether the selection condition described in the first embodiment is satisfied, in the first defrosting operation (left side of FIG. 12) performed following the first cooling operation, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches 20° C., which is the second defrost end temperature (normal defrosting operation). On the other hand, in the set time of the second cooling operation (right side of FIG. 12) shown in FIG. 12, the number of times the compressor is stopped is the same as the reference number of times, 1. In this case, the control unit determines that the third condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 12) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the third condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the third condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0073] As described above, according to this embodiment, the compressor constituting the refrigeration cycle together with the cooler is provided, and the control unit performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the first defrosting end temperature when the third condition is satisfied in addition to the selection condition, that is, the number of times the compressor is stopped during the cooling operation is equal to or greater than the reference number, and performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the second defrosting end temperature when the selection condition and the third condition are not satisfied. In the third condition, the number of times the compressor constituting the refrigeration cycle is stopped is used as an index, and if the number of times the compressor is stopped during the cooling operation is equal to or greater than the reference number, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frosting of the cooler, and therefore it is estimated that the amount of frosting of the cooler is small. Therefore, if the defrosting end temperature is made different based on whether the third condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frosting of the cooler can be performed.

[0074] <Embodiment 6> A sixth embodiment will be described with reference to Fig. 13. In this sixth embodiment, a fourth condition is added to the selection conditions in the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 13 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0075] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a fourth condition is satisfied in addition to the selection conditions described in the first embodiment. In the fourth condition, the accumulated stop time during which the operation of the compressor constituting the refrigeration cycle is stopped during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 13, the control unit accumulates the time during which the operation of the compressor is stopped from the start to the end of the cooling operation, compares the accumulated stop time with a reference stop time (for example, 1.5 hours), and determines that the fourth condition is satisfied if it is equal to or greater than the reference stop time. The control unit acquires the time during which the operation of the compressor is stopped by measuring the input voltage to the compressor and the time during which the voltage is input. When the control unit detects that the inside temperature detected by the inside temperature sensor is equal to or lower than the inside temperature setting, the control unit temporarily stops the compressor and the condenser fan, and when the control unit detects that the inside temperature detected by the inside temperature sensor is equal to or higher than the inside temperature setting, the control unit controls the compressor and the condenser fan to resume operation. Here, if the accumulated stop time of the compressor during cooling operation is equal to or longer than the reference stop time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the accumulated stop time of the compressor during cooling operation is shorter than the reference stop time, it is estimated that the cooling performance of the refrigeration cycle is not properly exerted and the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0076] For example, the accumulated stop time of the compressor during the first cooling operation (left side of FIG. 13) shown in FIG. 13 is 1 hour, which is shorter than the reference stop time of 1.5 hours. In this case, the control unit determines that the fourth condition is not satisfied, and in the first defrosting operation (left side of FIG. 13) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied, the defrost heater heats the cooler until the temperature (defrost temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20° C. (normal defrosting operation). On the other hand, the accumulated stop time of the compressor during the second cooling operation (right side of FIG. 13) shown in FIG. 13 is 2 hours, which is longer than the reference stop time of 1.5 hours. In this case, the control unit determines that the fourth condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 13) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the fourth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the fourth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0077] As described above, according to this embodiment, the compressor constituting the refrigeration cycle together with the cooler is provided, and the control unit performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the first defrosting end temperature when the fourth condition is satisfied in addition to the selection condition, that is, the accumulated stop time of the compressor during the cooling operation is equal to or greater than the reference stop time, and performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the second defrosting end temperature when the selection condition and the fourth condition are not satisfied. In the fourth condition, the accumulated stop time of the compressor is used as an index, and if the accumulated stop time of the compressor during the cooling operation is equal to or greater than the reference stop time, the cooling performance of the refrigeration cycle is properly exerted even when the compressor is operating at a low speed, and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frosting of the cooler, and it is estimated that the amount of frosting of the cooler is small. Therefore, if the defrosting end temperature is made different based on whether the fourth condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frosting of the cooler can be performed.

[0078] <Embodiment 7> A seventh embodiment will be described with reference to Fig. 14. In this seventh embodiment, a fifth condition is added to the selection conditions in the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those in the first embodiment will be omitted. Also, the notation in Fig. 14 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0079] In this embodiment, the control unit performs a defrosting operation so as to change the defrost end temperature based on whether or not a fifth condition is satisfied in addition to the selection conditions described in the first embodiment. In the fifth condition, the average rotation speed per unit time of the compressor constituting the refrigeration cycle during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 14, the control unit calculates the average rotation speed per unit time of the compressor from the start to the end of the cooling operation, compares the average rotation speed with a reference rotation speed (e.g., 20 rotations / second), and determines that the fifth condition is satisfied if the average rotation speed is equal to or lower than the reference rotation speed. Note that FIG. 14 shows the drive frequency (unit: "Hz") and average rotation speed (unit: "rotations / second") of the compressor. The control unit increases or decreases the rotation speed per unit time of the compressor based on the inside temperature detected by the inside temperature sensor, and controls the rotation speed to be higher when the inside temperature is equal to or higher than the inside temperature setting compared to when the inside temperature is lower than the inside temperature setting. Here, if the average number of revolutions per unit time of the compressor during cooling operation is equal to or less than the reference number of revolutions, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the average number of revolutions per unit time of the compressor during cooling operation is greater than the reference number of revolutions, it can be estimated that the cooling performance of the refrigeration cycle is not properly exerted and the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0080] For example, the average rotation speed per unit time of the compressor during the first cooling operation (left side of FIG. 14) shown in FIG. 14 is 70 times / second, which is higher than the reference number of times of 20 times / second. In this case, the control unit determines that the fifth condition is not satisfied, and causes the defrost heater to heat the cooler until the temperature (defrost temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrost operation) in the first defrost operation (left side of FIG. 14) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied or not. On the other hand, the average rotation speed per unit time of the compressor during the second cooling operation (right side of FIG. 14) shown in FIG. 14 is 20 times / second, which is the same as the reference number of times. In this case, the control unit determines that the fifth condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 14) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the fifth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the fifth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0081] As described above, according to this embodiment, the compressor constituting the refrigeration cycle together with the cooler is provided, and the control unit performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the first defrosting end temperature when the fifth condition is satisfied, in addition to the selection condition, that is, the average rotation speed of the compressor during the cooling operation is equal to or lower than the reference rotation speed, and performs the defrosting operation until the temperature detected by the defrosting temperature sensor becomes the second defrosting end temperature when the selection condition and the fifth condition are not satisfied. In the fifth condition, the average rotation speed of the compressor is used as an index, and if the average rotation speed of the compressor during the cooling operation is equal to or lower than the reference rotation speed, the cooling performance of the refrigeration cycle is properly exhibited even when the compressor is operating at a low speed, and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frosting of the cooler, and it is estimated that the amount of frosting of the cooler is small. Therefore, if the defrosting end temperature is made different based on whether the fifth condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frosting of the cooler can be performed.

[0082] <Embodiment 8> An eighth embodiment will be described with reference to Fig. 15. In this eighth embodiment, a sixth condition is added to the selection conditions in the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those in the first embodiment will be omitted. Also, the notation in Fig. 15 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0083] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a sixth condition is satisfied in addition to the selection conditions described in the first embodiment. In the sixth condition, the average current value of the compressor constituting the refrigeration cycle during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 15, the control unit calculates the average current value of the compressor from the start to the end of the cooling operation, compares the average current value with a reference value (e.g., 0.5 A), and determines that the sixth condition is satisfied if the average current value is equal to or less than the reference value. Note that FIG. 15 shows the average current value of the compressor. The control unit increases or decreases the current value of the compressor based on the internal temperature detected by the internal temperature sensor, and controls the current value to be larger when the internal temperature is equal to or higher than the internal temperature setting compared to when the internal temperature is lower than the internal temperature setting. Note that when the compressor is driven at a constant voltage, if the current value of the compressor fluctuates as described above, the power value of the compressor will fluctuate accordingly. Here, if the average current value of the compressor during cooling operation is equal to or less than the reference value, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the average current value of the compressor during cooling operation is greater than the reference value, it can be estimated that the cooling performance of the refrigeration cycle is not properly exerted and the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0084] For example, the average current value of the compressor during the first cooling operation (left side of FIG. 15) shown in FIG. 15 is set to 1 A, which is higher than the reference value of 0.5 A. In this case, the control unit determines that the sixth condition is not satisfied, and, regardless of whether the selection condition described in the first embodiment is satisfied, in the first defrosting operation (left side of FIG. 15) performed following the first cooling operation, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20° C. (normal defrosting operation). On the other hand, the average current value of the compressor during the second cooling operation (right side of FIG. 15) shown in FIG. 15 is set to 0.5 A, which is the same as the reference value. In this case, if the control unit determines that the sixth condition is satisfied and also satisfies the selection condition described in the first embodiment, in the second defrosting operation (on the right side of FIG. 15) performed following the second cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the sixth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. If the defrost end temperature is varied based on whether or not the sixth condition is satisfied in addition to the selection condition, a defrosting operation appropriate to the amount of frost on the cooler can be performed. FIG. 15 illustrates an example in which the average current value of the compressor is used as an index, but it is also possible to use the power value of the compressor, which is a numerical value that varies in conjunction with the current value, as an index.

[0085] As described above, according to this embodiment, the compressor constituting the refrigeration cycle together with the cooler is provided, and the control unit performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature when the sixth condition is satisfied in which the average current value or power value of the compressor is equal to or lower than the reference value during the cooling operation in addition to the selection condition, and performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature when the selection condition and the sixth condition are not satisfied. In the sixth condition, the average current value or power value of the compressor is used as an index, and if the average current value or power value of the compressor is equal to or lower than the reference value during the cooling operation, the cooling performance of the refrigeration cycle is properly exhibited even when the compressor is operating at a low speed, and the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation of the cooler, and it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is made different based on whether the sixth condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frost formation on the cooler can be performed.

[0086] <Embodiment 9> A ninth embodiment will be described with reference to Fig. 16. In this ninth embodiment, a seventh condition is added to the selection conditions of the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 16 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0087] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a seventh condition is satisfied in addition to the selection conditions described in the first embodiment. The seventh condition uses the accumulated stop time during which the operation of the interior fan is stopped during the cooling operation performed immediately before the defrosting operation as an index. Specifically, as shown in FIG. 16, the control unit accumulates the time during which the operation of the interior fan is stopped from the start to the end of the cooling operation, compares the accumulated stop time with a reference stop time (for example, 1.5 hours), and determines that the seventh condition is satisfied if it is equal to or greater than the reference stop time. The control unit obtains the time during which the operation of the interior fan is stopped by measuring the input voltage to the interior fan and the time during which the voltage is input. When the control unit detects that the interior temperature detected by the interior temperature sensor is equal to or lower than the interior set temperature, the control unit temporarily stops the compressor, the condenser fan, and the interior fan, and when the control unit detects that the interior temperature detected by the interior temperature sensor is equal to or higher than the interior set temperature, the control unit controls the compressor, the condenser fan, and the interior fan to resume operation. Here, if the accumulated stop time of the interior fan during cooling operation is equal to or longer than the reference stop time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled, and the heat exchange efficiency of the refrigeration cycle has not decreased significantly due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the accumulated stop time of the interior fan during cooling operation is shorter than the reference stop time, it is estimated that the cooling performance of the refrigeration cycle is not properly exerted and the heat exchange efficiency of the refrigeration cycle has decreased due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0088] For example, the accumulated stop time of the interior fan during the first cooling operation (left side of FIG. 16) shown in FIG. 16 is 1 hour, which is shorter than the reference stop time of 1.5 hours. In this case, the control unit determines that the seventh condition is not satisfied, and in the first defrosting operation (left side of FIG. 16) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied, the control unit causes the defrost heater to heat the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrosting operation). On the other hand, the accumulated stop time of the interior fan during the second cooling operation (right side of FIG. 16) shown in FIG. 16 is 2 hours, which is longer than the reference stop time of 1.5 hours. In this case, the control unit determines that the seventh condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 16) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3°C, which is the first defrost end temperature (simple defrosting operation). Note that even if the seventh condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the seventh condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0089] As described above, according to this embodiment, the storage unit is provided with an internal fan arranged in the storage unit body to circulate the air inside the storage unit, and the control unit performs a defrosting operation until the temperature detected by the defrosting temperature sensor becomes the first defrosting end temperature when the seventh condition, in which the accumulated stop time of the internal fan during cooling operation is equal to or greater than the reference stop time, is satisfied in addition to the selection condition, and performs a defrosting operation until the temperature detected by the defrosting temperature sensor becomes the second defrosting end temperature when the selection condition and the seventh condition are not satisfied. In the seventh condition, the accumulated stop time of the internal fan is used as an index, and if the accumulated stop time of the internal fan during cooling operation is equal to or greater than the reference stop time, the cooling performance of the refrigeration cycle is properly exerted even when the internal fan is operating at a low speed, and the interior of the storage unit is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrosting end temperature is made different based on whether the seventh condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frost formation on the cooler can be performed.

[0090] <Embodiment 10> A tenth embodiment will be described with reference to Fig. 17. In this tenth embodiment, an eighth condition is added to the selection conditions from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 17 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0091] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not an eighth condition is satisfied in addition to the selection conditions described in the first embodiment. The eighth condition uses the accumulated low-speed operation time of the low-speed operation in which the internal fan is operated at a low speed during the cooling operation performed immediately before the defrosting operation as an index. Specifically, as shown in FIG. 17, the control unit accumulates the time during which the internal fan is operated at a low speed from the start to the end of the cooling operation, compares the accumulated low-speed operation time with a reference operation time (e.g., 1.5 hours), and determines that the eighth condition is satisfied if it is equal to or greater than the reference operation time. The control unit operates the internal fan at a high speed while the compressor is operating during the cooling operation, operates the internal fan at a low speed while the compressor is stopped during the cooling operation, and stops the operation of the internal fan during the defrosting operation. In FIG. 17, the high-speed operation state of the interior fan is indicated as "ON (high speed)", the low-speed operation state of the interior fan is indicated as "ON (low speed)", and the stopped state is indicated as "OFF". In addition, the control unit temporarily stops the compressor and the condenser fan when it is detected that the interior temperature detected by the interior temperature sensor is equal to or lower than the interior set temperature, and controls the compressor and the condenser fan to resume operation when it is detected that the interior temperature detected by the interior temperature sensor is equal to or higher than the interior set temperature. Here, if the accumulated low-speed operation time of the interior fan during cooling operation is equal to or higher than the reference operation time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Conversely, if the accumulated low-speed operation time of the internal fan during cooling operation is shorter than the standard operation time, it is estimated that the cooling performance of the refrigeration cycle is not being properly performed, and the heat exchange efficiency of the refrigeration cycle has decreased due to frost formation on the cooler, resulting in a large amount of frost formation on the cooler.

[0092] For example, the accumulated low-speed operation time of the interior fan during the first cooling operation (left side of FIG. 17) shown in FIG. 17 is 1 hour, which is shorter than the reference operation time of 1.5 hours. In this case, the control unit determines that the eighth condition is not satisfied, and in the first defrosting operation (left side of FIG. 17) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20°C (normal defrosting operation). On the other hand, the accumulated low-speed operation time of the interior fan during the second cooling operation (right side of FIG. 17) shown in FIG. 17 is 2 hours, which is longer than the reference operation time of 1.5 hours. In this case, the control unit determines that the eighth condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 17) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the eighth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the eighth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0093] As described above, according to this embodiment, the storage unit is provided with a compressor which configures a refrigeration cycle together with the cooler, and an internal fan which is arranged in the storage unit body and circulates the air inside the storage unit, and the control unit operates the internal fan at high speed while the compressor is operating, operates the internal fan at low speed while the compressor is stopped, and stops operation of the internal fan during defrosting operation, and performs a defrosting operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature if an eighth condition is satisfied in addition to the selection condition, that is, the accumulated low-speed operation time of the internal fan during cooling operation is equal to or longer than the reference operation time, and performs a defrosting operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature if the selection condition and the eighth condition are not satisfied. The eighth condition uses the cumulative low-speed operation time of the interior fan, whose operation speed is controlled in synchronization with the operating state of the compressor, as an index, and if the cumulative low-speed operation time of the interior fan during cooling operation is equal to or longer than the reference operation time, it means that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled even if the compressor and the interior fan are operating at low speed, and it can be said that the heat exchange efficiency of the refrigeration cycle has not decreased significantly due to frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is made different based on whether the eighth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrost operation according to the amount of frost formation on the cooler.

[0094] <Embodiment 11> An eleventh embodiment will be described with reference to Fig. 18. In this eleventh embodiment, a ninth condition is added to the selection conditions from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation of 18 in the figure is the same as that in Figs. 4 to 8 described in the first embodiment.

[0095] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not the ninth condition is satisfied in addition to the selection conditions described in the first embodiment. In the ninth condition, the average current value of the interior fan during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 18, the control unit calculates the average current value of the interior fan from the start to the end of the cooling operation, compares the average current value with a reference value (e.g., 0.05 A), and determines that the ninth condition is satisfied if the average current value is equal to or less than the reference value. Note that FIG. 18 shows the average current value of the interior fan. The control unit increases or decreases the current value of the interior fan based on the interior temperature detected by the interior temperature sensor, and controls the current value to be larger when the interior temperature is equal to or higher than the interior set temperature compared to when the interior temperature is lower than the interior set temperature. Note that when the interior fan is driven at a constant voltage, if the current value of the interior fan fluctuates as described above, the power value of the interior fan will fluctuate accordingly. Here, if the average current value of the internal fan during cooling operation is equal to or less than the reference value, it can be said that the cooling performance of the refrigeration cycle is being properly exerted and the interior of the refrigerator is being properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the average current value of the internal fan during cooling operation is greater than the reference value, it can be estimated that the cooling performance of the refrigeration cycle is not being properly exerted and the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0096] For example, the average current value of the internal fan during the first cooling operation (left side of FIG. 18) shown in FIG. 18 is 0.1 A, which is higher than the reference value of 0.05 A. In this case, the control unit determines that the ninth condition is not satisfied, and, regardless of whether the selection condition described in the first embodiment is satisfied, in the first defrosting operation (left side of FIG. 18) performed following the first cooling operation, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20° C. (normal defrosting operation). On the other hand, the average current value of the internal fan during the second cooling operation (right side of FIG. 18) shown in FIG. 18 is 0.05 A, which is the same as the reference value. In this case, if the control unit determines that the ninth condition is satisfied and also satisfies the selection condition described in the first embodiment, in the second defrosting operation (on the right side of FIG. 18) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3°C, which is the first defrost end temperature (simple defrosting operation). Note that even if the ninth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. If the defrost end temperature is varied based on whether or not the ninth condition is satisfied in addition to the selection condition, an appropriate defrosting operation can be performed according to the amount of frost on the cooler. FIG. 18 illustrates a case where the average current value of the interior fan is used as an index, but it is also possible to use the power value of the interior fan, which is a numerical value that varies in conjunction with the current value, as an index.

[0097] As described above, according to this embodiment, the storage unit includes an internal fan disposed in the storage unit body to circulate the air inside the storage unit, and the control unit performs a defrosting operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature when the ninth condition, in addition to the selection condition, is satisfied, in which the average current value or power value of the internal fan is equal to or lower than the reference value during the cooling operation, and performs a defrosting operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature when the selection condition and the ninth condition are not satisfied. In the ninth condition, the average current value or power value of the internal fan is used as an index, and if the average current value or power value of the internal fan is equal to or lower than the reference value during the cooling operation, the cooling performance of the refrigeration cycle is properly exhibited even when the internal fan is operating at a low speed, and the interior of the storage unit is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation of the cooler, and it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is made different based on whether the ninth condition is satisfied in addition to the selection condition, an appropriate defrosting operation according to the amount of frost formation on the cooler can be performed.

[0098] <Embodiment 12> A twelfth embodiment will be described with reference to Fig. 19. In this twelfth embodiment, a tenth condition is added to the selection conditions from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 19 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0099] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not a tenth condition is satisfied in addition to the selection conditions described in the first embodiment. In the tenth condition, the accumulated stop time during which the operation of the condenser fan is stopped during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 19, the control unit accumulates the time during which the operation of the condenser fan is stopped from the start to the end of the cooling operation, compares the accumulated stop time with a reference stop time (for example, 1.5 hours), and determines that the tenth condition is satisfied if it is equal to or greater than the reference stop time. The control unit acquires the time during which the operation of the condenser fan is stopped by measuring the input voltage to the condenser fan or the time during which the voltage is input. When the control unit detects that the temperature inside the cabinet detected by the cabinet temperature sensor is equal to or lower than the cabinet set temperature, the control unit temporarily stops the compressor and the condenser fan, and when the control unit detects that the temperature inside the cabinet detected by the cabinet temperature sensor is equal to or higher than the cabinet set temperature, the control unit controls the compressor and the condenser fan to resume operation. Here, if the cumulative stop time of the condenser fan during cooling operation is equal to or longer than the reference stop time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the cumulative stop time of the condenser fan during cooling operation is shorter than the reference stop time, it can be estimated that the cooling performance of the refrigeration cycle is not properly exerted and the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, so that the amount of frost formation on the cooler is large.

[0100] For example, the cumulative stop time of the condenser fan during the first cooling operation (left side of FIG. 19) shown in FIG. 19 is 1 hour, which is shorter than the reference stop time of 1.5 hours. In this case, the control unit determines that the tenth condition is not satisfied, and regardless of whether the selection condition described in the first embodiment is satisfied, in the first defrosting operation (left side of FIG. 19) performed following the first cooling operation, the defrost heater heats the cooler until the temperature (defrosting temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20° C. (normal defrosting operation). On the other hand, the cumulative stop time of the condenser fan during the second cooling operation (right side of FIG. 19) shown in FIG. 19 is 2 hours, which is longer than the reference stop time of 1.5 hours. In this case, the control unit determines that the tenth condition is satisfied, and if the selection condition described in the first embodiment is also satisfied, in the second defrosting operation (on the right side of FIG. 19) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the tenth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. By varying the defrost end temperature based on whether or not the tenth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0101] As described above, according to this embodiment, the condenser constituting the refrigeration cycle together with the cooler and the condenser fan blowing air to the condenser are provided, and the control unit performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature when the tenth condition is satisfied in which the cumulative stop time of the condenser fan during the cooling operation is equal to or longer than the reference stop time in addition to the selection condition, and performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature when the selection condition and the tenth condition are not satisfied. In the tenth condition, the cumulative stop time of the condenser fan blowing air to the condenser is used as an index, and if the cumulative stop time of the condenser fan during the cooling operation is equal to or longer than the reference stop time, the cooling performance of the refrigeration cycle is properly exhibited even if the condenser fan is operating at a low speed, and the inside of the refrigerator is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is varied based on whether or not the tenth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0102] <Embodiment 13> A thirteenth embodiment will be described with reference to Fig. 20. In this thirteenth embodiment, an eleventh condition is added to the selection conditions from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 20 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0103] In this embodiment, the control unit performs a defrosting operation so as to vary the defrost end temperature based on whether or not an eleventh condition is satisfied in addition to the selection conditions described in the first embodiment. In the eleventh condition, the average current value of the condenser fan during the cooling operation performed immediately before the defrosting operation is used as an index. Specifically, as shown in FIG. 20, the control unit calculates the average current value of the condenser fan from the start to the end of the cooling operation, compares the average current value with a reference value (e.g., 0.05 A), and determines that the eleventh condition is satisfied if the average current value is equal to or less than the reference value. Note that FIG. 20 shows the average current value of the condenser fan. The control unit increases or decreases the current value of the condenser fan based on the internal temperature detected by the internal temperature sensor, and controls the current value to be larger when the internal temperature is equal to or higher than the internal temperature setting compared to when the internal temperature is lower than the internal temperature setting. Note that when the condenser fan is driven at a constant voltage, if the current value of the condenser fan fluctuates as described above, the power value of the condenser fan will fluctuate accordingly. Here, if the average current value of the condenser fan during cooling operation is equal to or less than the reference value, it can be said that the cooling performance of the refrigeration cycle is properly exerted, the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, so it is estimated that the amount of frost formation on the cooler is small. Conversely, if the average current value of the condenser fan during cooling operation is greater than the reference value, it can be estimated that the cooling performance of the refrigeration cycle is not properly exerted, the heat exchange efficiency of the refrigeration cycle is reduced due to frost formation on the cooler, and the amount of frost formation on the cooler is large.

[0104] For example, the average current value of the condenser fan during the first cooling operation (left side of FIG. 20) shown in FIG. 20 is 0.1 A, which is higher than the reference value of 0.05 A. In this case, the control unit determines that the eleventh condition is not satisfied, and causes the defrost heater to heat the cooler until the temperature (defrost temperature) detected by the defrost temperature sensor reaches the second defrost end temperature of 20° C. (normal defrost operation) in the first defrost operation (left side of FIG. 20) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied. On the other hand, the average current value of the condenser fan during the second cooling operation (right side of FIG. 20) shown in FIG. 20 is 0.05 A, which is the same as the reference value. In this case, if the control unit determines that the eleventh condition is satisfied and also satisfies the selection condition described in the first embodiment, in the second defrosting operation (on the right side of FIG. 20) performed following the second cooling operation, the control unit causes the defrost heater to heat the cooler until the temperature detected by the defrost temperature sensor reaches 3° C., which is the first defrost end temperature (simple defrosting operation). Note that even if the eleventh condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. If the defrost end temperature is varied based on whether or not the eleventh condition is satisfied in addition to the selection condition, an appropriate defrosting operation can be performed according to the amount of frost on the cooler. FIG. 20 illustrates a case in which the average current value of the condenser fan is used as an index, but it is also possible to use the power value of the condenser fan, which is a numerical value that varies in conjunction with the current value, as an index.

[0105] As described above, according to this embodiment, the condenser constituting the refrigeration cycle together with the cooler and the condenser fan blowing air to the condenser are provided, and the control unit performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature when the eleventh condition is satisfied in which the average current value or power value of the condenser fan is equal to or lower than the reference value during the cooling operation in addition to the selection condition, and performs the defrosting operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature when the selection condition and the eleventh condition are not satisfied. In the eleventh condition, the average current value or power value of the condenser fan is used as an index, and if the average current value or power value of the condenser fan is equal to or lower than the reference value during the cooling operation, the cooling performance of the refrigeration cycle is properly exhibited even if the condenser fan is operating at a low speed, and the inside of the refrigerator is properly cooled, and it can be said that the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to the frost formation of the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is varied based on whether or not the eleventh condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0106] <Embodiment 14> A fourteenth embodiment will be described with reference to Fig. 21. In this fourteenth embodiment, a twelfth condition is added to the selection conditions from the first embodiment. Note that a duplicated description of the structure, action, and effect similar to those of the first embodiment will be omitted. Also, the notation in Fig. 21 is the same as that in Figs. 4 to 8 described in the first embodiment.

[0107] In this embodiment, the control unit performs a defrosting operation so as to change the defrost end temperature based on whether or not the 12th condition is satisfied in addition to the selection conditions described in the first embodiment. In the 12th condition, the index is the cumulative time during which the temperature detected by the clogging temperature sensor during the cooling operation performed immediately before the defrosting operation is lower than the reference temperature. Specifically, as shown in FIG. 21, the control unit accumulates the time during which the temperature detected by the clogging temperature sensor during the operation of the compressor is lower than the reference temperature (e.g., 30°C) from the start to the end of the cooling operation, and compares the accumulated time with the reference accumulated time (e.g., 1.5 hours) and determines that the 12th condition is satisfied if it is equal to or greater than the reference accumulated time. In FIG. 21, the temperature detected by the clogging temperature sensor is shown together with the reference temperature (broken line in the figure). This reference temperature is an assumed value of the ambient temperature (outdoor air temperature) of the freezer. The temperature detected by the clogging temperature sensor when the compressor and the condenser fan are in operation is, for example, about 35°C, which is higher than the above-mentioned reference temperature, whereas the temperature detected by the clogging temperature sensor when the compressor and the condenser fan are stopped tends to be about the same as or lower than the above-mentioned reference temperature. From this, it can be said that if the accumulated time during which the temperature detected by the clogging temperature sensor is higher than the reference temperature is long, the refrigeration cycle is in high operation, and if the accumulated time during which the temperature detected by the clogging temperature sensor is lower than the reference temperature is long, the refrigeration cycle is in low operation. Therefore, if the accumulated time during which the temperature detected by the clogging temperature sensor is below the reference temperature is longer than the reference accumulated time, the cooling performance of the refrigeration cycle is properly exerted, the inside of the refrigerator is properly cooled, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Conversely, if the accumulated time during which the temperature detected by the clogging temperature sensor is below the reference temperature is shorter than the reference accumulated time, it is estimated that the cooling performance of the refrigeration cycle is not being properly performed, and the heat exchange efficiency of the refrigeration cycle has decreased due to frost formation in the cooler, resulting in a large amount of frost formation in the cooler.

[0108] For example, the cumulative time during which the temperature detected by the clogging temperature sensor during the first cooling operation (left side of FIG. 21) is equal to or lower than the reference temperature is set to 1 hour, which is shorter than the reference cumulative time of 1.5 hours. In this case, the control unit determines that the twelfth condition is not satisfied, and in the first defrosting operation (left side of FIG. 21) performed following the first cooling operation, regardless of whether the selection condition described in the first embodiment is satisfied, the control unit causes the defrost heater to heat the cooler until the temperature (defrosting temperature) detected by the defrosting temperature sensor reaches 20° C., which is the second defrost end temperature (normal defrosting operation). On the other hand, the cumulative time during which the temperature detected by the clogging temperature sensor during the second cooling operation (right side of FIG. 21) is equal to or lower than the reference temperature is set to 2 hours, which is longer than the reference cumulative time of 1.5 hours. In this case, if the control unit determines that the twelfth condition is satisfied and also satisfies the selection condition described in the first embodiment, in the second defrosting operation (on the right side of FIG. 21) performed following the second cooling operation, the defrost heater heats the cooler until the temperature detected by the defrost temperature sensor reaches 3°C, which is the first defrost end temperature (simple defrosting operation). Note that even if the twelfth condition is satisfied, if the selection condition described in the first embodiment is not satisfied, the control unit performs a normal defrosting operation. Also, in the two cooling operations shown in FIG. 21, there is a timing at which the compressor and the condenser fan are temporarily stopped. This is because, when it is detected that the inside temperature detected by the inside temperature sensor is equal to or lower than the inside temperature setting, the control unit temporarily stops the compressor and the condenser fan, and when it is detected that the inside temperature detected by the inside temperature sensor is equal to or higher than the inside temperature setting, the control unit controls the compressor and the condenser fan to resume operation. By varying the defrost end temperature based on whether or not the twelfth condition is satisfied in addition to the selection condition, it is possible to perform an appropriate defrosting operation according to the amount of frost on the cooler.

[0109] As described above, according to this embodiment, the control unit is provided with a compressor which configures a refrigeration cycle together with the cooler, a condenser which configures a refrigeration cycle together with the cooler and the compressor, a condenser fan which blows air to the condenser, and a clog temperature sensor (condenser temperature sensor) which detects the temperature of the condenser or near the condenser, and in addition to the selection condition, if the control unit satisfies a twelfth condition which indicates that the accumulated time during which the temperature detected by the clog temperature sensor during cooling operation is lower than the reference temperature is equal to or longer than the reference accumulated time, the control unit performs a defrost operation until the temperature detected by the defrost temperature sensor becomes the first defrost end temperature, and if the selection condition and the twelfth condition are not satisfied, the control unit performs a defrost operation until the temperature detected by the defrost temperature sensor becomes the second defrost end temperature. The twelfth condition uses the cumulative time during which the temperature detected by the clogging temperature sensor during cooling operation becomes lower than the reference temperature as an index, and if the cumulative time during cooling operation is equal to or longer than the reference cumulative time, it can be said that the cooling performance of the refrigeration cycle is properly exerted and the interior of the refrigerator is properly cooled even when the compressor is operating at a low speed, and the heat exchange efficiency of the refrigeration cycle is not significantly reduced due to frost formation on the cooler, and therefore it is estimated that the amount of frost formation on the cooler is small. Therefore, if the defrost end temperature is made different based on whether the twelfth condition is satisfied in addition to the selection condition, an appropriate defrost operation can be performed according to the amount of frost formation on the cooler.

[0110] <Other embodiments> The technology disclosed in this specification is not limited to the embodiments described above and illustrated in the drawings, and for example, the following embodiments are also included within the technical scope.

[0111] (1) It is also possible to add an outside air temperature sensor (ambient temperature thermistor) for detecting the outside air temperature (ambient temperature) of the freezer 10. In this case, when the control unit 20 satisfies a thirteenth condition in which the outside air temperature detected by the outside air temperature sensor is equal to or higher than a reference temperature (e.g., 25°C) in addition to the selection condition, the control unit 20 performs a defrost operation until the temperature detected by the defrost temperature sensor 29 becomes the first defrost end temperature, and when the selection condition and the thirteenth condition are not satisfied, the control unit 20 performs a defrost operation until the temperature detected by the defrost temperature sensor 29 becomes the second defrost end temperature.

[0112] (2) The second condition can be changed to "the internal temperature detected by internal temperature sensor 46 at the set time immediately before the defrosting operation is equal to or higher than the reference set temperature."

[0113] (3) The third condition can also be changed to "the difference between the internal temperature detected by the internal temperature sensor 46 and the internal set temperature from the time the cooling operation is started to the time it is ended is equal to or less than a reference value."

[0114] (4) The first condition can also be changed to "the number of times that the internal temperature detected by the internal temperature sensor 46 becomes equal to or higher than the door opening / closing detection temperature during the set time immediately before the defrosting operation is equal to or less than a reference number."

[0115] (5) The first condition can also be changed to the following: "The total number of times that the internal temperature detected by the internal temperature sensor 44 during cooling operation is equal to or higher than the door opening / closing detection temperature is divided by the cooling operation time to calculate the number of openings and closings per unit time, and the number of openings and closings per unit time is equal to or less than a reference number."

[0116] (6) The specific value of the reference number of times related to the first condition described in the first embodiment can be changed to two or more times.

[0117] (7) The specific value of the set time period related to the first condition described in the first embodiment can be set to be shorter or longer than 15 minutes.

[0118] (8) The specific value of the reference number of times related to the first condition described in the second embodiment can be changed to once or three or more times.

[0119] (9) The specific value of the reference set temperature for the second condition may be changed to a temperature other than -22°C.

[0120] (10) The specific numerical value of the reference value for the third condition may be changed to an absolute temperature other than 1 K.

[0121] (11) The specific value of the set time period related to the third condition may be set to be shorter or longer than two hours.

[0122] (12) The specific value of the reference defrost temperature according to the fourth condition may be changed to a temperature other than -28°C.

[0123] (13) The specific value of the set time period related to the fourth condition described in the first embodiment can be set to be shorter or longer than 15 minutes.

[0124] (14) The specific value of the reference accumulated time related to the second condition described in the fourth embodiment can be shorter or longer than two hours.

[0125] (15) The specific value of the set time period related to the third condition described in the fifth embodiment can be shorter or longer than two hours. In addition, the reference number of times related to the third condition can be two or more times.

[0126] (16) The third condition described in the fifth embodiment can also be changed to "the number of times that the compressor 22 is stopped during the period from when the cooling operation is started to when it is ended is equal to or greater than a reference number."

[0127] (17) The specific value of the reference stop time according to the fourth condition described in the sixth embodiment can be set shorter or longer than 1.5 hours.

[0128] (18) The specific value of the reference rotation speed according to the fifth condition described in the seventh embodiment can be set to be higher or lower than 20 revolutions per second.

[0129] (19) The specific numerical value of the reference value for the sixth condition described in the eighth embodiment can be set to be greater or less than 0.5 A.

[0130] (20) The specific value of the reference stop time according to the seventh condition described in the ninth embodiment can be set shorter or longer than 1.5 hours.

[0131] (21) The specific value of the standard operation time related to the eighth condition described in the tenth embodiment can be shorter or longer than 1.5 hours.

[0132] (22) The specific numerical value of the reference value for the ninth condition described in the eleventh embodiment can be set to be greater or less than 0.05A.

[0133] (23) The specific value of the reference stop time related to the tenth condition described in the twelfth embodiment can be shorter or longer than 1.5 hours.

[0134] (24) The specific numerical value of the reference value for the eleventh condition described in the thirteenth embodiment may be set to be greater or less than 0.05A.

[0135] (25) The specific value of the reference accumulated time related to the twelfth condition described in the fourteenth embodiment may be shorter or longer than 1.5 hours.

[0136] (26) In addition to the heater defrost method, the control unit 20 may perform an off-cycle defrost method in which the operation of the cooling device 18 is stopped and the internal fan 44 is operated to melt the frost adhering to the cooler 28.

[0137] (27) The present technology can also be applied to cooling storage units other than the freezer 10 (e.g., refrigerators). [Explanation of symbols]

[0138] 10...freezer (cooled storage), 12...storage body, 12A...opening, 14...door, 20...control unit, 22...compressor, 24...condenser fan, 25...clogging temperature sensor (third sensor), 26...condenser, 27...defrost heater (heating unit), 28...cooler (evaporator), 29...defrost temperature sensor (second sensor), 44...internal fan, 46...internal temperature sensor (first sensor)

Claims

1. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit, when performing the defrosting operation, selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether at least any of the first condition, the second condition, the third condition, and the fourth condition are satisfied.

2. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the third condition is satisfied when performing the defrosting operation, and the third condition is that the difference between the internal temperature detected by the first sensor and the internal set temperature at least at a set time immediately before the defrosting operation is equal to or less than a reference value.

3. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the fourth condition is satisfied when performing the defrosting operation, and the fourth condition is that the temperature detected by the second sensor at a set time immediately before the defrosting operation is equal to or higher than a reference defrost temperature.

4. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if, in addition to the selection condition, a second condition is satisfied in which the accumulated time during which the internal temperature detected by the first sensor during the cooling operation is below the internal set temperature is equal to or longer than a standard accumulated time, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the second condition are not satisfied.

5. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a compressor that configures the refrigeration cycle together with the evaporator, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a third condition is satisfied in addition to the selection condition, the third condition being that the number of times the compressor is stopped during the cooling operation is equal to or greater than a reference number, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the third condition are not satisfied.

6. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a compressor that configures the refrigeration cycle together with the evaporator, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a fifth condition is satisfied in addition to the selection condition, that is, the average rotation speed of the compressor is equal to or lower than a reference rotation speed during the cooling operation, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the fifth condition are not satisfied.

7. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a compressor that configures the refrigeration cycle together with the evaporator, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a sixth condition is satisfied in addition to the selection condition, that is, an average current value or power value of the compressor is equal to or lower than a reference value during the cooling operation, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the sixth condition are not satisfied.

8. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; An interior fan disposed in the storage body to circulate air inside the storage, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a seventh condition is satisfied in addition to the selection condition, that is, an accumulated stop time of the internal fan during the cooling operation is equal to or longer than a reference stop time, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the seventh condition are not satisfied.

9. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a condenser which configures the refrigeration cycle together with the evaporator; A condenser fan that blows air to the condenser, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, A cooling storage facility as described in claim 1, wherein the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a tenth condition is satisfied in which the integrated stop time of the condenser fan during the cooling operation is equal to or longer than a reference stop time in addition to the selection condition, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the tenth condition are not satisfied.

10. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a condenser which configures the refrigeration cycle together with the evaporator; A condenser fan that blows air to the condenser, The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if an eleventh condition is satisfied in addition to the selection condition, that is, an average current value or power value of the condenser fan becomes equal to or lower than a reference value during the cooling operation, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the eleventh condition are not satisfied.

11. A storage body having an opening; A door for opening and closing the opening; A first sensor that detects an internal temperature of the storage unit; An evaporator that constitutes a refrigeration cycle; A heating unit that heats the evaporator; A second sensor that detects a temperature of the evaporator or a temperature near the evaporator; A control unit that performs a cooling operation by controlling the refrigeration cycle so that the inside temperature detected by the first sensor becomes a set inside temperature, and controls the heating unit to perform a defrosting operation until the temperature detected by the second sensor becomes a defrost end temperature; a compressor which configures the refrigeration cycle together with the evaporator; a condenser which configures the refrigeration cycle together with the evaporator and the compressor; A condenser fan that blows air to the condenser; a third sensor that detects a temperature of the condenser or a temperature near the condenser; The control unit detects opening and closing of the door when the inside temperature detected by the first sensor becomes equal to or higher than a predetermined door opening and closing detection temperature, and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when at least one selection condition selected from among a first condition that the number of times that the inside temperature detected by the first sensor during the cooling operation becomes equal to or higher than the door opening and closing detection temperature is equal to or lower than a reference number of times, a second condition that the inside temperature set during the cooling operation is equal to or higher than a reference set temperature, a third condition that a difference between the inside temperature detected by the first sensor during the cooling operation and the inside temperature set during the cooling operation is equal to or lower than a reference value, and a fourth condition that the temperature detected by the second sensor during the cooling operation is equal to or higher than a reference defrosting temperature, is satisfied; and performs the defrosting operation until the temperature detected by the second sensor becomes equal to or higher than a first defrost end temperature, which is the defrost end temperature, when the selection condition is not satisfied, The control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if a twelfth condition is satisfied in addition to the selection condition, the accumulated time during which the temperature detected by the third sensor during the cooling operation is lower than a reference temperature is equal to or longer than the reference accumulated time, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the twelfth condition are not satisfied.

12. The control unit selects whether to use the first defrost end temperature or the second defrost end temperature as the defrost end temperature based on whether or not at least the first condition is satisfied when performing the defrosting operation, and the first condition is that the number of times that the internal temperature detected by the first sensor becomes equal to or higher than the door opening / closing detection temperature during a set time during the cooling operation is equal to or less than a reference number.

13. The compressor constitutes the refrigeration cycle together with the evaporator, 13. The cooling storage facility according to claim 1, wherein the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a fourth condition is satisfied in addition to the selection condition, the fourth condition being that an accumulated stop time of the compressor during the cooling operation is equal to or longer than a reference stop time, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the fourth condition are not satisfied.

14. a compressor which configures the refrigeration cycle together with the evaporator; An interior fan disposed in the storage body to circulate air inside the storage, 14. The refrigerated storage container according to any one of claims 1 to 13, wherein the control unit operates the internal fan at high speed while the compressor is operating, operates the internal fan at low speed while the compressor is stopped, stops operation of the internal fan during the defrosting operation, and performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature if an eighth condition is satisfied in addition to the selection condition, that is, an integrated low-speed operation time of the internal fan during the cooling operation is equal to or longer than a reference operation time, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature if the selection condition and the eighth condition are not satisfied.

15. The storage cabinet includes an internal fan disposed in the storage cabinet body to circulate air inside the storage cabinet, 15. The cooling storage container according to claim 1, wherein the control unit performs the defrosting operation until the temperature detected by the second sensor becomes the first defrost end temperature when a ninth condition is satisfied in addition to the selection condition, the ninth condition being that an average current value or power value of the internal fan is equal to or lower than a reference value during the cooling operation, and performs the defrosting operation until the temperature detected by the second sensor becomes the second defrost end temperature when the selection condition and the ninth condition are not satisfied.

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