JP2018189340A - Cooling storage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress poor defrosting when defrosting by an off-cycle defrost method. SOLUTION: The evaporator 20 is provided with an evaporator 20, a compressor 17 for compressing a refrigerant and supplying it to the evaporator 20, an internal thermista 29 for detecting the temperature inside the refrigerator, and a control unit 30, and the control unit 30 is provided with the control unit 30. When a predetermined condition is satisfied, the compressor 17 is stopped, but the evaporator 20 is not heated. The evaporator 20 is defrosted by the off-cycle defrost method, and then the temperature inside the refrigerator is equal to or higher than the off-cycle defrost end temperature. Refrigerator 1 that finishes defrosting when the state of is continued for 5 minutes. [Selection diagram] FIG. 4

Description

  The technology disclosed in this specification relates to a cold storage.

  Conventionally, as a defrosting method for melting frost adhering to the evaporator, an off-cycle defrosting method is known in which the compressor is stopped while the evaporator is not heated by a defrosting heater and the frost is melted by the rise in the internal temperature. (For example, refer to Patent Document 1). In the refrigerator described in Patent Literature 1, when off-cycle defrosting is started, completion of defrosting is detected when the indicated value of the cold air temperature sensor exceeds a predetermined temperature.

JP 2005-226865 A

  By the way, when performing defrosting by an off-cycle defrost method, the door of the cooling storage may be opened. When the door is opened, the internal temperature rises. Therefore, in the refrigerator described in Patent Document 1 described above, even if the defrosting is not completed, the defrosting ends when the door is opened, resulting in a defrosting failure. There is a fear. If the defrosting failure occurs, the cooling capacity may be reduced, resulting in a cooling failure.

  In this specification, the technique which suppresses the defrost failure at the time of defrosting by an off-cycle defrost system is disclosed.

  A cooling storage disclosed in the present specification includes an evaporator, a compressor that compresses a refrigerant and supplies the refrigerant to the evaporator, an internal temperature sensor that detects an internal temperature, and a control unit, and the control The unit starts defrosting of the evaporator by an off-cycle defrost method when a predetermined condition is satisfied, and then ends the defrosting when a state where the internal temperature is equal to or higher than the off-cycle defrost end temperature continues for a certain time.

When the door is opened during defrosting using the off-cycle defrost method, the internal temperature may rise to the off-cycle defrost end temperature or more, but if the door is closed immediately, the off-cycle defrost The state above the end temperature does not last long. On the other hand, when the defrosting by the off-cycle defrost method is sufficiently performed, the state that is equal to or higher than the off-cycle defrost end temperature continues for a long time.
According to the above cooling storage, when the defrosting is performed by the off-cycle defrost method, even if the internal temperature becomes higher than the off-cycle defrost end temperature, the state above the off-cycle defrost end temperature does not continue for a certain period of time. Since the frost is not terminated, the defrosting by the off-cycle defrost method is continued when the door is opened and immediately closed. For this reason, compared with the case where a defrost is complete | finished as soon as the inside temperature rises to off-cycle defrost end temperature, the defrost failure can be suppressed.

  Further, the certain time may be a time within a range of 3 minutes to 7 minutes.

  Even if the door is opened and the internal temperature rises if the fixed time is too short, the state where the internal temperature is equal to or higher than the off-cycle defrost end temperature will continue for a fixed time. Regardless, the defrosting is not complete and there is a risk of defrosting failure. For this reason, it is not preferable that the fixed time is too short. However, if the predetermined time is too long, the defrosting is continued even though the defrosting is sufficiently performed, so that the internal temperature may be excessively increased. For this reason, it is not desirable to be too long.

  If the fixed time is in the range of 3 to 7 minutes, the inventor's experience is not too short and not too long, so that the defrosting is completed even though the defrosting is not completed. While suppressing, it can also suppress that defrosting is continued even if it fully defrosts.

Front view of the cooling storage according to the first embodiment Sectional view of the AA line shown in FIG. Block diagram showing the electrical configuration of the cooling storage Graph for explaining cooling operation and defrosting operation

<Embodiment 1>
The first embodiment will be described with reference to FIGS. In the following description, the vertical direction and the horizontal direction are based on the vertical direction and the horizontal direction shown in FIG. 1, and the front-rear direction is based on the front-back direction shown in FIG.

(1) Whole structure of refrigerator With reference to FIGS. 1-3, the whole structure of the refrigerator 1 as a cooling storage which concerns on this embodiment is demonstrated. The refrigerator 1 is a four-door refrigerator mainly used for business.
As shown in FIG. 1, the refrigerator 1 includes a storage body 11 made of a heat insulating box having an opening 11 </ b> A (see FIG. 2) on the front surface. Two pairs of left and right double-spread type heat insulating doors 12 (12 </ b> A to 12 </ b> D) that open and close the opening 11 </ b> A are attached to the storage body 11 vertically. Further, four legs 13 that support the storage body 11 are attached to the lower surface of the storage body 11.

A machine room 14 whose upper side is open is provided on the storage body 11. The machine room 14 houses a cooling unit 15 (see FIG. 2), a control unit 30 (see FIG. 3), a power supply unit (not shown), and the like which will be described later.
An operation unit 16 is provided on the front surface of the machine room 14. The user can operate the operation unit 16 to perform various operations such as setting the target temperature in the storage. Here, in the refrigerator 1, the target temperature can be set to a minus temperature range. In the following description, the target temperature set by the user is referred to as set temperature.

(2) Configuration of Cooling Unit and its Peripheral Next, the configuration of the cooling unit 15 and its surroundings will be described with reference to FIG. The cooling unit 15 is unitized by attaching a compressor 17 for compressing a refrigerant, a condenser 18, a condenser fan 19, an evaporator 20, a capillary tube (not shown) and the like to a heat insulating unit base 21. The compressor 17, the condenser 18, the condenser fan 19 and the capillary tube are arranged on the upper side of the unit table 21, and the evaporator 20 is arranged on the lower side of the unit table 21.

The unit base 21 is formed to be slightly larger than the opening 23 formed in the ceiling wall 22 of the storage body 11, and is disposed on the ceiling wall 22 so as to close the opening 23.
The evaporator 20 performs heat exchange between the low-temperature refrigerant and the internal air, and the refrigerant pipes are folded back in a multiple manner so as to penetrate a plurality of plate-like cooling fins arranged in parallel. Since the evaporator 20 is arranged below the unit table 21, the evaporator 20 is not accommodated in the machine room 14, and an air circulation path 28 constituted by the ceiling (the ceiling wall 22 and the unit table 21) and the duct portion 24. Is housed in.

The defrost heater 31 is for melting frost attached to the evaporator 20, and is attached to the lower end of the cooling fin of the evaporator 20.
The duct portion 24 forms an air circulation path 28 between itself and the ceiling, and functions as a drain pan that receives defrost water that is water in which frost attached to the evaporator 20 has melted. A suction port is formed on the front side of the bottom wall of the duct portion 24, and the internal fan 26 is attached to the suction port. Moreover, the rear end of the bottom wall of the duct part 24 does not reach the rear wall of the storage body 11, and a blow-out port is formed between the rear end of the duct part 24 and the rear wall of the storage body 11. ing.

  Moreover, the duct part 24 is attached with the attitude | position in which the bottom face inclined, and the drainage groove 27 is extended from the rear end. The front end portion of the drainage groove 27 is inserted into a drainage port formed in the rear wall of the storage body 11, and the defrost water received by the duct portion 24 is on the rear side of the drainage groove 27 and the storage body 11. It is discharged out of the warehouse through the pipe 11B embedded in the wall.

The internal fan 26 is for circulating the cold air cooled by the evaporator 20 into the internal space. When the internal fan 26 rotates, the internal air is sucked into the air circulation path 28 from the suction port, cooled by the evaporator 20, and blown out from the outlet to the interior.
The internal thermistor 29 (an example of the internal temperature sensor) detects the internal temperature. The internal thermistor 29 is arranged between the internal fan 26 and the evaporator 20 in the air circulation path 28.

(3) Electrical configuration of refrigerator Next, the electrical configuration of the refrigerator 1 will be described with reference to FIG. The refrigerator 1 includes a control unit 30. The control unit 30 includes a CPU 30A, a ROM 30B, a RAM 30C, and the like, and controls each unit of the refrigerator 1 by executing a control program stored in the ROM 30B. The control unit 30 is connected to the operation unit 16, the compressor 17, the internal thermistor 29, the internal fan 26, the condenser fan 19, the defrosting heater 31, and the like.

  Note that the control unit 30 may include an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or the like instead of the CPU 30A.

(4) Cooling operation and defrosting operation Next, with reference to FIG. 4, the cooling operation and the defrosting operation which are performed by the control part 30 are demonstrated.

(4-1) Cooling Operation First, the cooling operation will be described. In the cooling operation, the compressor 17 and the condenser fan 19 are operated, and the internal fan 26 is rotated to maintain the internal temperature within a preset cooling temperature range. The upper limit temperature (not shown in FIG. 4) of the cooling temperature range is, for example, a set temperature + 2K [Kelvin], and the lower limit temperature is a set temperature -2K [Kelvin].

When the refrigerator 1 is turned on, the control unit 30 performs a pull-down operation that lowers the internal temperature to the upper limit temperature of the cooling temperature range, and shifts to the cooling operation when the internal temperature reaches the upper limit temperature.
In the cooling operation, the control unit 30 operates the compressor 17 and the condenser fan 19 at a lower rotational speed than the pull-down operation, and rotates the internal fan 26. The control unit 30 detects the internal temperature at every predetermined sampling time, and stops the compressor 17 and the condenser fan 19 when the internal temperature reaches the lower limit temperature of the cooling temperature range. When the compressor 17 and the condenser fan 19 are stopped, the internal temperature gradually rises. When the internal temperature reaches the upper limit temperature of the cooling temperature range, the control unit 30 resumes the operation of the compressor 17 and the condenser fan 19. By repeating this, the internal temperature is maintained within the cooling temperature range.

(4-2) Defrosting operation Next, the defrosting operation will be described. When the defrosting start condition is satisfied during the cooling operation, the control unit 30 performs the defrosting operation in order to melt the frost attached to the evaporator 20. Here, in this embodiment, there are a heater defrost method and an off-cycle defrost method as the defrosting method. When the defrosting start condition is satisfied, the control unit 30 determines which defrosting method is used for defrosting, and performs defrosting using the determined defrosting method. This will be specifically described below.

  First, defrosting start conditions will be described. The defrosting start condition is “a fixed time (for example, 6 hours) has passed since the last defrosting of the evaporator 20”, “a preset time has been reached”, or the like. In addition, defrost start conditions are not limited to these, It can determine suitably.

  Next, the heater defrost method and the off-cycle defrost method will be described. The heater defrost method is a method for defrosting using the defrost heater 31. In the heater defrost method, the control unit 30 stops the compressor 17, the condenser fan 19, and the internal fan 26 and energizes the defrost heater 31 to heat the evaporator 20. And the control part 30 will stop the electricity supply to the defrost heater 31, if internal temperature rises to heater defrost end temperature.

  However, the control unit 30 does not restart the operation of the compressor 17, the condenser fan 19 and the internal fan 26 immediately after draining the evaporator 20 even if the energization to the defrost heater 31 is stopped. When elapses, the operation of the compressor 17, the condenser fan 19 and the internal fan 26 is resumed. As a result, the defrosting by the heater defrost method is completed and the cooling operation is resumed.

The heater defrost system heats the evaporator 20 and thus has a high defrosting capability, but has the following disadvantages.
・ Power consumption increases by energizing the defrost heater.
-Since the internal temperature rises by energizing the defrost heater, the power consumption of the refrigerator 1 increases in the subsequent cooling operation.
-Since the internal temperature rises due to energization of the defrosting heater, there is a risk that the stored items in the internal compartment will deteriorate due to temperature changes.

  The off-cycle defrost method is a method for defrosting without using the defrost heater 31. In the off-cycle defrost system, the control unit 30 stops the compressor 17 and the condenser fan 19 while keeping the internal fan 26 rotated. Further, in the off-cycle defrost method, the control unit 30 does not energize the defrost heater 31.

  When the frosting amount of the evaporator 20 is small, it can be sufficiently defrosted even by an off-cycle defrost method. Specifically, when the compressor 17 is stopped, the internal temperature rises. Therefore, when the amount of frost formation is small, the internal air that rises by the internal fan 26 even if the defrost heater 31 is not energized. It can be sufficiently defrosted by circulation.

And the control part 30 will complete | finish the defrosting by an off-cycle defrost system, and will return to cooling operation, if the state whose internal temperature is more than an off-cycle defrost end temperature continues for 5 minutes (an example of fixed time). The off-cycle defrost end temperature is lower than the heater defrost end temperature.
In the off-cycle defrost method, since the defrost heater 31 is not energized, the disadvantages of the heater defrost method can be suppressed, while the defrosting capability is inferior to that of the heater defrost method.

Next, the determination of which defrosting method is used when the defrosting start condition is satisfied will be described.
Here, first, the relationship between the internal temperature and the amount of frost formation will be described. When the heat insulating door 12 of the refrigerator 1 is opened and closed, air outside the cabinet (hereinafter referred to as outside air) enters the cabinet. Normally, the outside air is higher in humidity than the air in the cabinet, so that frost tends to adhere to the evaporator 20 when the outside air enters. When the amount of frost formation on the evaporator 20 increases due to many door opening and closing, etc., the cooling performance of the refrigerator 1 decreases, so the internal temperature increases before the start of defrosting. For this reason, when the internal temperature is high before the start of defrosting, it is desirable to defrost by the heater defrost method in order to melt a large amount of frost.

  Conversely, when the door opening / closing is small and the amount of frost formation on the evaporator 20 is small, the cooling performance of the refrigerator 1 does not decrease, so the internal temperature becomes low even before the start of defrosting. For this reason, when the inside temperature is low, it is desirable to defrost by the off-cycle defrost method in order to suppress the disadvantages of the heater defrost method.

  However, even when the internal temperature is high, there is a case where the internal temperature is temporarily increased by opening the heat insulating door 12 immediately before. In that case, since the amount of frost formation is small, there is a demerit that power consumption increases when defrosting is performed by the heater defrost method.

Therefore, when the defrosting start condition is satisfied, the control unit 30 determines whether or not the internal temperature is always equal to or higher than the off-cycle defrost end temperature within the immediately preceding 5 minutes (an example of a fixed time), and always the off-cycle defrost. When the temperature is equal to or higher than the end temperature, it is determined that the amount of frost formation is large, and defrosting is performed by a heater defrost method.
On the other hand, if there is a period in which the internal temperature is less than the off-cycle defrost end temperature within 5 minutes, even if there is a period in which the internal temperature is temporarily higher than the off-cycle defrost end temperature within 5 minutes The control unit 30 determines that the amount of frost formation is small, and performs defrosting by an off-cycle defrost method. “When there is a period in which the internal temperature is lower than the end temperature of off-cycle defrost within 5 minutes” is an example of the predetermined condition.

For example, in the example shown in FIG. 4, the defrosting start condition is satisfied at time T2. And in the period from the time T1 to the time T2, which is the time 5 minutes before the time T2, the internal temperature is always equal to or higher than the off-cycle defrost end temperature. For this reason, the control part 30 starts defrosting by the heater defrost system in the time T2.
In the example shown in FIG. 4, the internal temperature reaches the heater defrost end temperature at time T3. For this reason, the control part 30 stops electricity supply to the defrost heater 31 at the time T3.

In the example shown in FIG. 4, the defrosting start condition is satisfied again at time T6. And the temperature in a store | warehouse | chamber is always less than off cycle defrost end temperature from the time T5 which is the time of 5 minutes before the time T6 to the time T6. For this reason, the control part 30 starts defrosting by the off-cycle defrost system in time T6.
And in the example shown in FIG. 4, the heat insulation door 12 is opened and closed during the defrosting by an off-cycle defrost system, and the internal temperature reaches the off-cycle defrost end temperature at the time T7. However, the state in which the internal temperature is equal to or higher than the off-cycle defrost end temperature does not continue until time T8, which is 5 minutes after time T7. For this reason, the control part 30 continues defrosting by an off-cycle defrost system also after the time T8.

  In the example shown in FIG. 4, the time when the internal temperature reaches the off-cycle defrost end temperature at time T9 and the state where the internal temperature is equal to or higher than the off-cycle defrost end temperature is a time point 5 minutes after time T9. It continues until T10. For this reason, the control part 30 complete | finishes the defrosting by an off-cycle defrost system in time T10, and returns to cooling operation.

(5) Effects of the embodiment According to the refrigerator 1 according to the first embodiment described above, the off-cycle defrost is performed even when the internal temperature becomes equal to or higher than the off-cycle defrost end temperature when the defrosting is performed by the off-cycle defrost method. Since the defrosting is not completed unless the temperature equal to or higher than the end temperature is continued for 5 minutes, the defrosting by the off-cycle defrosting method is continued when the heat insulating door 12 is immediately closed even if it is opened. For this reason, compared with the case where a defrost is complete | finished as soon as the inside temperature rises to off-cycle defrost end temperature, the defrost failure can be suppressed.

  Moreover, according to the refrigerator 1, a fixed time (here 5 minutes) is the time within the range of 3 minutes to 7 minutes. If the heat insulation door 12 is opened and the internal temperature rises if the predetermined time is too short, the state where the internal temperature is equal to or higher than the off-cycle defrost end temperature continues for a predetermined time, so defrosting is not completed. Nevertheless, the defrosting may end and there may be a defrosting failure. For this reason, it is not preferable that the fixed time is too short. However, if the predetermined time is too long, the defrosting is continued even though the defrosting is sufficiently performed, so that the internal temperature may be excessively increased. For this reason, it is not desirable to be too long.

  If the fixed time is in the range of 3 to 7 minutes, the inventor's experience is not too short and not too long, so that the defrosting is completed even though the defrosting is not completed. While suppressing, it can also suppress that defrosting is continued even if it fully defrosts.

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

  (1) In the above embodiment, the fixed time is 5 minutes as an example, but the fixed time is not limited to 5 minutes. However, as described above, it is not preferable that the predetermined time is too long or too short.

  (2) In the above embodiment, the case where “there is a period in which the internal temperature is less than the off-cycle defrost end temperature within 5 minutes” has been described as an example of the predetermined condition. However, the predetermined condition is not limited to this. . For example, when the defrost heater 31 is not provided and defrosting is always performed by the off-cycle defrost method, the above-described defrost start condition is an example of the predetermined condition.

  (3) Although the refrigerator 1 was demonstrated to the example in the said embodiment as a cooling storage, a freezer may be sufficient as a cooling storage.

DESCRIPTION OF SYMBOLS 1 ... Refrigerator (an example of cooling storage), 17 ... Compressor, 20 ... Evaporator, 29 ... Inside thermistor (an example of inside temperature sensor), 30 ... Control part

Claims (2)

An evaporator,
A compressor that compresses a refrigerant and supplies the refrigerant to the evaporator;
An internal temperature sensor for detecting the internal temperature,
A control unit;
With
The control unit starts defrosting of the evaporator by an off-cycle defrost method when a predetermined condition is satisfied, and then ends the defrosting when a state in which the internal temperature is equal to or higher than the off-cycle defrost end temperature continues for a certain period of time. , Cooling storage. The cooling storage according to claim 1,
The cooling storage, wherein the predetermined time is within a range of 3 to 7 minutes.

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