JP2018189339A - Cooling storage - Google Patents

Abstract

There is provided a cooling storage that can suppress power consumption required for defrosting while sufficiently defrosting an evaporator. The evaporator defrosting method includes a heater defrosting method and an off-cycle defrosting method, and the control unit finishes the off-cycle defrosting within 5 minutes immediately before starting the defrosting of the evaporator. If the temperature is higher than the temperature, it is judged that the amount of frost formation is large, and defrosting is performed by the heater defrost method. Frost. [Selection] Figure 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, the compressor is stopped and the evaporator is heated by the heating unit, and the compressor is stopped while heating is performed as compared with the heating defrosting method. There is known a heating suppression defrosting method that suppresses heating by a section and melts frost by increasing the internal temperature (for example, see Patent Document 1).
In the refrigerator described in Patent Document 1, when the set temperature is set to, for example, −15 ° C. to −25 ° C., the radiant heater (corresponding to the heating unit) is energized to defrost the evaporator (heating defrost method). When the set temperature is set to, for example, 5 ° C. or higher, defrosting is performed by off-cycle defrost in order to reduce the power consumption of the radiant heater (corresponding to a heating suppression defrosting method).

JP 2005-226865 A

  However, the amount of frost (frosting amount) adhering to the evaporator is not necessarily proportional to the set temperature, and even if the set temperature is low, the frost amount may be small. According to the refrigerator described in Patent Document 1, when the set temperature is low (for example, in the case of −15 ° C. to −25 ° C.), defrosting is performed by the heating defrosting method regardless of the amount of frost formation. When the amount is small, there is a possibility that power is wasted.

  In the present specification, a technique for suppressing power consumption required for defrosting while sufficiently defrosting an evaporator is disclosed.

  The cooling storage disclosed in the present specification includes an evaporator, a compressor that compresses refrigerant and supplies the refrigerant to the evaporator, a heating unit that heats the evaporator, and an internal temperature sensor that detects the internal temperature. A defrosting method for the evaporator, wherein the compressor is stopped and the evaporator is heated by the heating unit, and when the internal temperature rises to the heating defrosting end temperature, the defrosting is performed. The heating defrosting method that terminates the heating and the compressor is stopped, while the heating by the heating unit is suppressed as compared with the heating defrosting method, and the internal temperature is lower than the heating defrosting termination temperature. There is a heating suppression defrosting method in which the defrosting is terminated when it rises to the end temperature, and the control unit has the inside temperature within the certain time immediately before starting the defrosting of the evaporator, the heating suppression defrosting end temperature If it is above, defrost by the heating defrost method. If the it was less than the heating suppress defrosting end temperature defrosting by heating suppress defrosting method.

When the door of the cooling storage is opened and closed, outside air enters the storage. Normally, the outside air has a higher humidity than the air in the cabinet, so that frost tends to adhere to the evaporator when the outside air enters. When the amount of frost formation on the evaporator increases due to many reasons such as door opening / closing, the cooling performance of the cooling storage is lowered, and thus the internal temperature becomes high 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 a heating defrosting method in order to surely defrost.
Conversely, when the door opening / closing is small and the amount of frost formation on the evaporator is small, the cooling performance of the cooling storage is not lowered, so the internal temperature is lowered even before the start of defrosting. When the amount of frost formation is small, it can be sufficiently defrosted even by the heat suppression defrosting method. For this reason, when the internal temperature is low, it is desirable to defrost by a heating suppression defrosting method in order to suppress power consumption.
According to the above cooling storage, if the internal temperature is equal to or higher than the heat suppression defrost end temperature within a certain time immediately before starting the defrosting of the evaporator, it is defrosted by the heating defrosting method, and the heat suppression defrosting is performed. When the temperature is lower than the end temperature, the defrosting is performed by the heating suppression defrosting method. Therefore, the evaporator is compared with the case where the defrosting by the heating defrosting method or the defrosting by the heating suppression defrosting method is determined by the set temperature. Power consumption required for defrosting can be suppressed while sufficiently defrosting.

  Moreover, the said control part defrosts by the said heating defrost system, when the internal temperature is always more than the said heating suppression defrost end temperature within the fixed time immediately before starting the defrost of the said evaporator, If there is a period during which the internal temperature is lower than the heating suppression defrosting end temperature within the predetermined time, even if there is a period that is temporarily higher than the heating suppression defrosting end temperature, the temperature is removed by the heating suppression defrosting method. It may be frosted.

Even if there is a period in which the internal temperature is equal to or higher than the heating suppression defrost end temperature within a certain time, the door may be opened just before and temporarily exceed the heating suppression defrost end temperature. In that case, since the amount of frost formation is small, if defrosting is performed by the heat defrosting method, power is wasted.
According to the above cooling storage, even if the internal temperature is equal to or higher than the heating suppression defrosting end temperature within a certain time immediately before starting the defrosting of the evaporator, it is temporary (in other words, If there is a period in which the internal temperature is equal to or higher than the heat suppression defrost end temperature within a certain time, but the internal temperature is less than the heat suppression defrost end temperature within the predetermined time) Since the defrosting is performed by the frost method, even if the internal temperature is equal to or higher than the heating suppression defrosting end temperature, the evaporator is removed while sufficiently defrosting compared to the case of defrosting by the heating defrosting method. The power consumption required for frost can be further suppressed.

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

If the fixed time is too long, there is a possibility that the amount of frost on the evaporator will increase if the door opens and closes after that even if there is a period in which the internal temperature is lower than the heating suppression defrost end temperature. Even in that case, if the defrosting is performed by the heat suppression defrosting method, the defrosting may be caused. For this reason, it is not preferable that the predetermined time is too long.
However, if the fixed time is too short, even if the internal temperature is always equal to or higher than the heat suppression defrost end temperature, it is only temporarily higher than the heat suppression defrost end temperature by opening and closing the door, and the amount of frost formation is small. There is also a possibility, and when defrosting by the heating defrosting method, there is a risk that power is wasted. For this reason, it is not desirable that the fixed time is too short.
When the fixed time is in the range of 3 minutes to 7 minutes, the inventor's experience is neither too short nor too long, so that wasteful consumption of power can be suppressed while suppressing defrosting failure.

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 (an example of a heating unit) is for melting frost adhering 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 (an example of a heat defrost method) and an off-cycle defrost method (an example of a heat suppression defrost method) as a defrost 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 (an example of heating 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 internal temperature rises to off cycle defrost end temperature (an example of a heating suppression defrost end temperature) lower than 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.

  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 T5. The internal temperature is temporarily higher than the off-cycle defrost end temperature due to, for example, the opening of the heat insulating door 12 during the period from time T4 to time T5, which is 5 minutes before time T5. There is also a period in which the off-cycle defrost end temperature is exceeded and the inside temperature is less than the off-cycle defrost end temperature within 5 minutes. That is, the internal temperature is not always higher than the off-cycle defrost end temperature.

  For this reason, the control part 30 starts a defrost by an off-cycle defrost system in the time T5. In the example shown in FIG. 4, the internal temperature reaches the off-cycle defrost end temperature at time T6. For this reason, the control part 30 complete | finishes defrosting at the time T6, and returns to cooling operation.

(5) Effect of Embodiment According to the refrigerator 1 according to Embodiment 1 described above, frost formation occurs when the internal temperature is equal to or higher than the off-cycle defrost end temperature within 5 minutes of starting the defrosting of the evaporator 20. If the amount is less than the end temperature of the off cycle defrost, it is judged that the amount of frost formation is small and the defrost is performed by the off cycle defrost method. Compared with the case where frost or defrost using an off-cycle defrost method is determined based on the set temperature, the power consumption required for defrosting can be suppressed while sufficiently defrosting the evaporator 20.

  Also, according to the refrigerator 1, even if the internal temperature is equal to or higher than the off-cycle defrost end temperature within 5 minutes, if it is temporary (in other words, the internal temperature is off-cycle defrost within 5 minutes). Even if there is a period that is higher than the end temperature, if the inside temperature is less than the off cycle defrost end temperature within 5 minutes), the inside temperature is temporarily defrosted by the off cycle defrost method. However, when the temperature is equal to or higher than the off-cycle defrost end temperature, the power consumption required for defrosting can be further suppressed while sufficiently defrosting the evaporator 20 as compared with the case where defrosting is performed by the heater defrost method.

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 fixed time is too long, the amount of frost on the evaporator 20 may increase when the door opens and closes after that even if the internal temperature is lower than the off-cycle defrost end temperature within the fixed time. There is sex. Even in such a case, if the defrosting is performed by the off-cycle defrosting method, the defrosting may be poor. For this reason, it is not preferable that the predetermined time is too long.
However, if the fixed time is too short, even if the internal temperature is always higher than the off-cycle defrost end temperature, it may be temporarily higher than the off-cycle defrost end temperature due to door opening and closing etc. There is also a risk that power is wasted if defrosting is performed by the heater defrost method. For this reason, it is not desirable that the fixed time is too short.
When the fixed time is in the range of 3 minutes to 7 minutes, the inventor's experience is neither too short nor too long, so that wasteful consumption of power can be suppressed while suppressing defrosting failure.

<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, if there is a period in which the internal temperature is less than the off-cycle defrost end temperature within 5 minutes immediately before the start of defrosting of the evaporator 20, it is temporarily above the off-cycle defrost end temperature. The case where defrosting is performed by the off-cycle defrost method even when there is a certain period has been described as an example. Conversely, if there is a period in which the internal temperature is equal to or higher than the off-cycle defrost end temperature within 5 minutes, defrosting is performed by the heater defrost method even if there is a period temporarily lower than the off-cycle defrost end temperature. May be.

  (2) In the above embodiment, the case where the evaporator 20 is heated by the defrost heater 31 is described as an example of the heating defrosting method. However, the evaporator 20 may be heated by supplying hot gas. In that case, a mechanism for supplying hot gas is an example of the heating unit.

  (3) Although the above embodiment has been described by taking 5 minutes as an example of the fixed time, 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.

  (4) In the above embodiment, the off-cycle defrost method is described as an example of the heat suppression defrost method, but the heat suppression defrost method is not limited to the off-cycle defrost method. For example, in the heating suppression defrosting method, the defrosting heater 31 may be energized in a range in which the power consumption is suppressed compared to the heater defrosting method.

  (5) Although the refrigerator 1 has been described as an example of the cooling storage in the above embodiment, the cooling storage may be a freezer.

DESCRIPTION OF SYMBOLS 1 ... Refrigerator (an example of cooling storage), 17 ... Compressor, 20 ... Evaporator, 29 ... Internal thermistor (an example of internal temperature sensor), 30 ... Control part, 31 ... Defrost heater (An example of a heating part)

Claims (3)

An evaporator,
A compressor that compresses a refrigerant and supplies the refrigerant to the evaporator;
A heating unit for heating the evaporator;
An internal temperature sensor for detecting the internal temperature,
A control unit;
With
The defrosting method of the evaporator includes a heating defrosting method that stops the compressor and heats the evaporator by the heating unit, and ends the defrosting when the internal temperature rises to the heating defrosting end temperature. While the compressor is stopped, heating by the heating unit is suppressed as compared with the heating defrosting method, and defrosting is performed when the internal temperature rises to a heating suppression defrosting termination temperature lower than the heating defrosting termination temperature. There is a heating suppression defrosting method that ends,
The controller defrosts by the heating defrosting method when the internal temperature is equal to or higher than the heating suppression defrosting end temperature within a certain time immediately before starting the defrosting of the evaporator, and the heating suppression When it is less than the defrost end temperature, it is a cooling storehouse that defrosts by the heat suppression defrost method. The cooling storage according to claim 1,
The controller defrosts by the heating defrosting method when the internal temperature is always equal to or higher than the heating suppression defrosting end temperature within a certain time immediately before starting the defrosting of the evaporator, and the constant defrosting is performed. When there is a period in which the internal temperature is lower than the heating suppression defrosting end temperature within a time, the heating suppression defrosting method is used to temporarily defrost even if there is a period of time equal to or higher than the heating suppression defrosting end temperature. , Cooling storage. The cooling storage according to claim 1 or 2,
The cooling storage, wherein the predetermined time is within a range of 3 to 7 minutes.

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