JP5722160B2 - Cooling storage - Google Patents

Description

  The present invention relates to a cooling storage for performing a defrosting operation of a cooler.

  Off-cycle defrosting is mentioned as an example of the defrosting method which removes the frost adhering to a cooler in a cooling storage etc. This off-cycle defrosting is a state in which the compressor constituting the refrigeration circuit is stopped, the supply of the refrigerant to the cooler is stopped, and the refrigerant in the cooler is recovered to the compressor side. By continuing to operate, the cooler temperature is increased by blowing air from the internal fan, so that the frost adhering to the cooler is melted and defrosted. The thing of patent document 1 is known as a cooling storehouse which performs such an off cycle defrost operation. The off-cycle defrosting operation described in Patent Document 1 is started periodically by a timer or manually. When the temperature of the cooler reaches the preset defrosting end temperature, the off-cycle defrosting operation is ended, and the compressor is restarted to resume the normal cooling operation for cooling the storage.

  In such off-cycle defrosting operation, defrosting is performed without heating the cooler with a heater or the like, and therefore the time required for defrosting is relatively long. For this reason, there was a possibility that the temperature in the cabinet that is not cooled during the off-cycle defrosting operation would rise and adversely affect the stored items. Therefore, as described in Patent Document 2, a method for suppressing a temperature rise in the storage during the defrosting operation by performing a pre-cooling operation for reducing the inside of the storage to a set temperature before the defrosting operation has been proposed. .

JP 2006-52878 A Japanese Unexamined Patent Publication No. 63-231182

  However, when the pre-cooling operation is performed as described above, a new problem arises. This can occur when a large amount of frost is attached to the cooler, for example, by frequently opening and closing the doors of the cooling storage. If the amount of frost formation on the cooler increases, the efficiency of heat exchange between the cooler and the internal air sent by the internal fan deteriorates, and the temperature in the storage becomes difficult to decrease. As a result, the pre-cooling operation does not end easily, and the subsequent off-cycle defrosting operation is not started, so the amount of frost formation on the cooler continues to increase, the heat exchange efficiency further deteriorates, and the temperature in the storage also decreases. It will fall into a vicious circle. Therefore, in order to cope with such circumstances, it is required to suppress the cooling failure and the defrosting failure while considering the balance between the internal cooling and the defrosting of the cooler.

  This invention is completed based on the above situations, Comprising: It aims at suppressing a cooling defect and a defrosting defect in the cooling storage which performs a defrost operation.

  The present invention relates to a storage for storing stored items, a cooling device including a cooler for cooling the inside of the storage, and the inside of the storage for circulating the inside air cooled by heat exchange with the cooler in the storage. By operating the fan, the internal thermistor for detecting the internal temperature of the storage, the cooler thermistor for detecting the temperature of the cooler, the cooling device and the internal fan, the internal temperature is set in advance. A cooling operation control unit that performs a cooling operation to be maintained near the set temperature and a defrosting start signal that receives the defrosting start signal, a precooling operation that cools the inside of the storage, and subsequently removes frost from the cooler A defrosting operation control unit that performs an operation, and the defrosting operation control unit receives a temperature difference calculation unit that calculates a temperature difference between the internal temperature and the cooler temperature, and the defrosting start signal. Before or during the pre-cooling operation A defrosting operation forcibly starting unit that compares the temperature difference calculated by the temperature difference calculating unit with a predetermined reference value and forcibly starts the defrosting operation on condition that the temperature difference exceeds the reference value. And having a feature.

  According to such a configuration, the amount of frost formation on the cooler can be determined based on the temperature difference between the internal temperature and the cooler temperature, and the presence / absence of the pre-cooling operation and the length can be adjusted. If it demonstrates in detail, it will be estimated that there is much frosting amount to a cooler that the temperature difference of internal temperature and cooler temperature is large. In such a state, the heat exchange efficiency between the cooler and the internal air sent by the internal fan is poor, and the temperature in the storage is not easily lowered even if the pre-cooling operation is performed. The effect of suppressing the increase in internal temperature is not good, and there is a possibility that it will lead to poor cooling in the subsequent chamber. Therefore, the defrosting operation control unit performs the defrosting operation with priority over the precooling operation by the defrosting operation forcible start unit, thereby reliably defrosting the cooler, and cooling failure in the subsequent cooling operation. Can be prevented. Moreover, since it is possible to suppress the pre-cooling operation being performed unnecessarily while the heat exchange efficiency between the cooler and the internal air is poor, it is possible to suppress the power consumption as a cooling storage.

  On the other hand, the fact that the temperature difference between the internal temperature and the cooler temperature is small is estimated that the amount of frost formation on the cooler is small. In such a state, the heat exchange efficiency between the cooler and the internal air is good, and the effect of suppressing the temperature rise during the defrosting operation by the pre-cooling operation is sufficiently exhibited. Therefore, the defrosting operation control unit can perform defrosting of the cooler while suppressing the increase in the internal temperature during the defrosting operation by performing the defrosting operation after performing the precooling as usual. it can. Thus, by performing the pre-cooling operation and the defrosting operation in consideration of the balance between the internal cooling and the defrosting of the cooler depending on the frosting amount of the cooler, the cooling failure and the defrosting failure are suppressed. Can do.

  The defrosting operation control unit includes a cooling operation state detection unit that detects whether the cooling device is in a cooling operation state or a stopped state when receiving the defrosting start signal, and the cooling operation When the operation state of the cooling device detected by the state detection unit is during the cooling operation, the cooling operation is continued, and when the operation is stopped, a pre-cooling operation is newly started, The continuous cooling operation and the pre-cooling operation may be terminated when the internal temperature reaches a predetermined defrosting start temperature.

  According to such a configuration, as long as the amount of frost formation is small and the defrosting operation forcible start unit is not forcibly started, the same defrosting start is performed regardless of the internal temperature at the start of the precooling operation. The pre-cooling operation ends when the temperature is reached. Therefore, in the above case, since the internal temperature at the start of the defrosting operation can be made uniform, if the defrosting start temperature is set in consideration of the time taken for the defrosting and the temperature range rising during that time, the defrosting is performed. It is possible to reliably suppress cooling failure such as the temperature inside the chamber rising during the time and adversely affecting the stored items.

  In addition, the pre-cooling operation is not performed in units of time, but is cooled until the internal temperature reaches the defrosting start temperature, so that the temperature of the cooler that cools the internal air is reduced to a certain amount. Can do. That is, the temperature distribution of the cooler is likely to vary, and if defrosting is started in such a dispersed state, frost may partially remain in the cooler. For this reason, by making the temperature distribution of the cooler constant by the pre-cooling operation, it is possible to suppress the defrosting failure and prevent the cooling failure that may occur due to partial frosting.

  ADVANTAGE OF THE INVENTION According to this invention, the cooling defect and defrosting defect can be suppressed in the cooling storehouse which performs a defrosting operation.

The circuit block diagram of the prefabricated refrigerator which concerns on one Embodiment of this invention Block diagram showing defrosting operation control mechanism Flow chart showing defrosting operation control operation Timing chart when cooling operation is performed when the defrost cycle timer is UP Timing chart when cooling operation is stopped at the time of defrost cycle timer UP A flowchart showing a defrosting operation control operation according to the second embodiment. Timing chart when cooling operation is stopped at the time of defrost cycle timer UP Timing chart related to defrosting operation control of related technology 1 Timing chart related to defrosting operation control of related technology 2

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
The cooling storage of this embodiment has illustrated the case where it applies to the prefabricated refrigerator 10. FIG.
First, the whole structure of the prefabricated refrigerator 10 is demonstrated using FIG. The prefabricated refrigerator 10 includes a refrigerator main body 11 formed in a rectangular box shape by assembling a plurality of heat insulating panels, and the inside thereof is a storage 12 that can store stored items. Although not shown, the wall surface of the refrigerator main body 11 is formed with an opening through which a stored item can be taken in and out, and a heat insulating door is attached so as to cover the doorway.

  A cooling device 20 is disposed across the refrigerator main body 11 inside and outside. The cooling device 20 includes a so-called refrigeration cycle, and includes a compressor 21, a condenser 22 including a condenser fan 22A, a receiver (liquid receiver) 23, a dryer 24, an expansion valve 25, a cooler (evaporator) 26, and the like. The refrigerant pipe 27 is circulated and connected. The expansion valve 25 and the cooler 26 are housed in the indoor unit 13 installed in the storage 12 and the rest are housed in the outdoor unit 14 installed outside the refrigerator main body 11. The cooling device 20 has a well-known configuration in which the refrigerant in the refrigerant pipe 27 is compressed by the compressor 21, dissipated by the condenser 22, and evaporated by the cooler 26. The cooling device 20 is provided with a pressure switch 28 that measures the refrigerant pressure on the suction side and the discharge side of the compressor 21 and forcibly stops the cooling device 20 when an abnormal pressure exceeding a predetermined range is detected. ing.

The indoor unit 13 includes a casing 15 that accommodates the cooler 26 and the like, and an inlet 15A and an outlet 15B are formed to be opposed to each other. In the vicinity of the suction port 15A on the outside of the casing 15, an in-compartment thermistor 16 that detects an in-compartment temperature t that is a temperature in the storage 12 is attached. On the other hand, in the casing 15, a cooler 26 and an internal fan 29 provided with a fan motor 29 </ b> A are disposed on the outlet 15 </ b> B side. Although not shown, the cooler 26 has a configuration in which a plurality of plate-like fins are arranged in parallel on the outer surface of the cooling pipe, and the cooler 26 is attached in contact with the fins so as to be inserted between the fins. A thermistor 17 is provided. The cooler thermistor 17 detects the condenser temperature t _e.

  As shown by the arrow in FIG. 1, the internal air in the storage 12 is sucked into the casing 15 from the inlet 15 </ b> A by the internal fan 29, and the internal air is heat-exchanged by the cooler 26. Then, the air in the warehouse cooled in the storage 12 is circulated and supplied by being blown out into the storage 12 from the outlet 15B.

Now, the operation control part 30 provided with the microcomputer is provided as what controls the compressor 21 and the internal fan 29 (refer FIG. 2). The input side of the operation control unit 30 counts the the internal thermistor 16 for detecting the inside temperature t in reservoir 12, cooler thermistor 17 for detecting the cooler temperature t _e, the defrost period time T _d A defrost cycle timer 40 is connected. The compressor 21 and the internal fan 29 are connected to the output side. The operation control unit 30, for cooling the cooling operation control unit 31 for controlling the cooling operation of maintaining the vicinity of the set temperature t _s which is preset 12 reservoirs, the 12 reservoir at predetermined defrost period T _d A defrosting operation control unit 32 that controls the precooling operation and subsequently the defrosting operation for removing the frost formation of the cooler 26 is provided.

The cooling operation control unit 31, a predetermined temperature higher ON temperature t _(ON) than the set temperature t _s which is calculated based on the preset temperature t _s, the predetermined temperature lower OFF temperature than the set temperature t _s t _(OFF) is stored. The cooling operation control unit 31 reads a signal from the internal thermistor 16, and compares the internal temperature t, which is the input value, with the ON temperature t _(ON) and the OFF temperature t _(OFF) . When the internal temperature t exceeds the ON temperature t _(ON) , the operation of the compressor 21 is started (or the operation state is continued), and when the internal temperature t is below the OFF temperature t _(OFF) , The operation of the compressor 21 is stopped (or the stopped state is continued). That is, based on the comparison result between the internal temperature t and the ON / OFF temperatures t _(ON) and t _(OFF) from the cooling operation control unit 31, an operation instruction or operation stop instruction signal is output to the compressor 21. . On the other hand, the detailed explanation of the internal fan 29 is omitted, but the cooling operation control unit 31 controls the operation in synchronization with the operation of the compressor 21, and performs predetermined intermittent operation or continuous operation while the compressor 21 is stopped. It is set to drive. Thus, the operation and cooling operation to repeat the stop of the compressor 21 and the internal fan 29, are the inside temperature t in reservoir 12 configured to maintain near a desired set temperature t _s.

Next, the defrosting operation control unit 32 will be described in detail.
Defrosting operation is performed for each predetermined defrost cycle time T _d, the defrost cycle timer 40 counts defrost cycle time by T _d elapses, indicating the defrosting operation defrosting operation control unit 32 A signal (corresponding to a defrosting start signal) is input. Then, the temperature difference calculating unit 33 of the defrosting operation control unit 32 calculates the temperature difference Δt between the input inside temperature t from the cooler temperature t _e from defrosting chamber in the thermistor 16 and the cooler thermistor 17. The temperature difference Δt calculated by the temperature difference calculation unit 33 is input to the defrosting operation forced start unit 34 and is compared with a predetermined forced start reference value _tfs . When the temperature difference Δt exceeds the forcible start reference value _tfs , the off-cycle defrosting operation is forcibly started.

On the other hand, when the temperature difference Δt is _less than the forced start reference value _tfs , the result is output to the cooling operation state detection unit 35. The cooling operation state detection unit 35 detects whether the compressor 21 is operating or stopped. When the compressor 21 is in operation, the operation state of the compressor 21 and the internal fan 29 is continued (see FIG. 4), and when the compressor 21 is stopped, the compressor 21 and the warehouse The operation of the inner fan 29 is newly started (see FIG. 5), and the pre-cooling operation is performed. This pre-cooling operation usually means that the inside of the storage 12 is defrosted at the start of defrosting temperature t ₁ (main) before the off-cycle defrosting operation is forcibly started by the defrosting operation forcible start unit 34. In the embodiment, it is a cooling operation for cooling to the OFF temperature t _(OFF) ). When the internal temperature t reaches this defrosting start temperature, the off-cycle defrosting operation is subsequently started.

Even during the pre-cooling operation, the temperature difference Delta] t _p has been calculated with the internal temperature t by the temperature difference calculator 33 and the cooler temperature t _e, the temperature difference Delta] t _p is in the defrosting operation started forcibly portion 34 It is input and compared with the forced start reference value _tfs . When the temperature difference Delta] t _p exceeds the forced start reference value t _fs immediately ends the pre-cooling operation, the off-cycle defrosting operation is started.

Here, the off-cycle defrosting operation will be described. In the off-cycle defrosting operation, first, the solenoid valve 27A located in front of the cooler 26 in FIG. 1 is closed to stop the supply of the refrigerant to the cooler 26, and the compressor 21 is continuously operated for a while. The refrigerant in 26 is recovered to the outdoor unit 14 side (compressor 21 side). Thereafter, the operation of the compressor 21 is stopped. On the other hand, the in-compartment fan 29 is continuously operated after the off-cycle defrosting operation is started. During the stop of the compressor 21, condenser temperature t _e is naturally or elevated frost generated in the cooling unit 26 by the blowing of the internal fan 29 is melted. These defrosted water and condensed water in which the frost has melted are discharged to the outside of the storage body 11 through a drain pan (not shown) or returned to the storage room 12 together with the air inside the storage room 29 by the internal fan 29 as water vapor. It is. In this way, the defrosting of condenser 26 is performed, when the condenser temperature t _e reaches the ON temperature t predetermined value α higher by defrosting ending temperature t ₂ from _(ON), the off-cycle defrosting operation is terminated The

Next, the operation of this embodiment will be described with reference to FIGS.
During cooling operation to maintain the set temperature t _s near the-compartment temperature t, when the defrost period time T _d passes ( "YES" in step S11), and if there are many frost formation amount of the cooler 26 ( In step S12, “YES”), the off-cycle defrosting operation is immediately started (step S13). Except when the amount of frost formation on the cooler 26 is particularly large (“NO” in step S12), the cooling operation is continued as shown in FIG. 4 (“YES” in step S14, step S15), and the compressor When 21 is stopped, the pre-cooling operation is newly started as shown in FIG. 5 (“NO” in step S14, step S16). When the inside of the storage 12 is cooled to the defrost start temperature t ₁ (t _(OFF) ) (“YES” in step S17), the off-cycle defrost operation is started (step S13).

If it is determined that the amount of frost on the cooler 26 is large during the pre-cooling operation ("NO" in step S17, "YES" in step S18), the pre-cooling operation is forcibly terminated (step S19). An off-cycle defrosting operation is started (step S13). When it is determined that the defrosting of the cooler 26 has been completed (“YES” in step S20), the off-cycle defrosting operation ends (step S21). Then, at the same time that the off-cycle defrosting operation is completed, the defrost cycle timer is reset and a new defrost cycle time _Td is started (step S10). In this way, the above operation is repeated every defrost cycle time _Td , and a defrosting operation according to the amount of frost on the cooler 26 is performed.

As described above, according to this embodiment, the temperature difference Delta] t between the inside temperature t and the cooler temperature t _e, by Delta] t _p, to determine the frost quantity on the cooler 26, the presence or absence of pre-cooling operation And the length can be adjusted. In detail, the temperature difference Delta] t between the inside temperature t and the cooler temperature t _e, that Delta] t _p is large, it is estimated that frost formation amount to the cooler 26 is large. In such a state, the heat exchange efficiency between the cooler 26 and the internal air sent by the internal fan 29 is poor, and the temperature t in the storage 12 is not easily lowered even if the pre-cooling operation is performed. The effect of suppressing the increase in the internal temperature t with respect to the power consumption is poor, and there is a possibility that it will lead to a subsequent cooling failure in the storage 12. Therefore, the defrosting operation control unit 32 reliably performs the defrosting of the cooler 26 by giving priority to the off-cycle defrosting operation over the precooling operation by the defrosting operation forcible start unit 34, and the subsequent cooling. Cooling failure during operation can be prevented. Moreover, since it is possible to suppress the pre-cooling operation being performed unnecessarily while the heat exchange efficiency between the cooler 26 and the internal air is poor, the power consumption of the prefabricated refrigerator 10 as a whole can be suppressed.

On the other hand, the internal temperature t temperature difference Delta] t between the cooler temperature t _e, that Delta] t _p is small, it is estimated that frost quantity to the cooler 26 is small. In such a state, the heat exchange efficiency between the cooler 26 and the internal air is good, and the effect of suppressing the temperature rise during the defrosting operation by the pre-cooling operation is sufficiently exhibited. Therefore, the defrosting operation control unit 32 performs the off-cycle defrosting operation after performing the pre-cooling as usual, thereby removing the cooler 26 while suppressing the rise in the internal temperature t during the off-cycle defrosting operation. Frost can be reliably performed. Thus, by performing the pre-cooling operation and the off-cycle defrosting operation in consideration of the balance between the internal cooling and the defrosting of the cooler 26 depending on the frost formation amount of the cooler 26, the cooling failure and the defrosting failure are performed. Can be suppressed.

Further, according to the operating state of the cooling operation state detection unit 35 a cooling device 20 detected by the to continue cooling operation, or newly started pre cooling operation, the inside temperature t defrosting start temperature t ₁ ( The pre-cooling operation is terminated when t _(OFF) is reached. For this reason, as long as the amount of frost formation is small and the off-cycle defrosting operation is not forcibly started by the defrosting operation forcing start unit 34, the same defrosting start temperature regardless of the internal temperature t at the start of the pre-cooling operation. the pre-cooling operation is completed when it reaches to t _1. Thus, in the above case, since it is possible to align the inside temperature t at the start off cycle defrosting operation of the defrosting start temperature t _1, taking into account the temperature range of the rise time according to the off cycle defrost and during by setting the defrost start temperature t ₁ that it is possible to reliably suppress the cooling defects such as adverse effects on-compartment temperature t is stored goods increased during the off cycle defrosting time.

Further, instead of hours prior cooling operation, by the inside temperature t is assumed to be cooled until reaching the defrosting start temperature t _1, it drops the condenser temperature t _e for cooling the air inside a fixed amount Can be aligned with the state. That is, the temperature distribution of the cooler 26 is likely to vary, and if defrosting is started in such a dispersed state, frost may partially remain in the cooler 26. For this reason, by making temperature distribution of the cooler 26 constant by the pre-cooling operation, it is possible to suppress the defrosting failure and prevent the cooling failure that may occur due to partial frosting.

Further, defrosting operation control unit 32, if it exceeds the condenser temperature t _e end preset defrost temperature t _2, exit the off cycle defrosting operation, at the time the off-cycle defrosting operation by managing with no cooler temperature t _e, reliably perform defrosting in the indoor unit 13 of the condenser 26 and around, it is possible to suppress the defrosting failure.

  Although the first embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and for example, the following modifications may be included. In the following modified examples, the same members as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof is omitted.

[Modification 1 of Embodiment 1]
A first modification of the first embodiment will be described. This modification is different from the first embodiment in that the length of the precooling operation is determined in advance as a predetermined precooling operation time. That is, in the embodiment 1, when the inside temperature t has reached the defrost start temperature t _1, or the defrosting operation is started forcibly unit 34 temperature difference Delta] t _p between the cooler temperature t _e and the inside temperature t is forced The pre-cooling operation is terminated when the start reference value _tfs is exceeded. On the other hand, in this modified example, since the precooling operation is controlled to be operated for a uniform precooling operation time, the precooling operation is forcibly performed by the defrosting operation forcing start unit 34. Even if the amount of frost on the cooler 26 is not so large that it is not terminated, the pre-cooling operation is terminated in a certain pre-cooling operation time.

Such a configuration is particularly useful when, for example, a new store is put into the storage 12 during the pre-cooling operation. That is, when a new heat load is applied to the storage 12, the internal temperature t does not readily reach the defrost start temperature t _{1 due} to factors other than frost formation on the cooler 26. In such a case, the off-cycle defrosting operation can be surely performed every predetermined time if the precooling operation is completed within a predetermined precooling operation time as in this modification. Therefore, even if the pre-cooling operation is controlled by time as described above, it is effective to suppress the defrosting failure.

[Modification 2 of Embodiment 1]
Next, a second modification of the first embodiment will be described. This modification is different from the first embodiment in that the start of counting the defrost cycle time _Td by the defrost cycle timer 40 is not linked to the end of the off-cycle defrost operation (see step S21 and step S10 in FIG. 3). To do. That is, apart from the defrosting operation control operation shown in FIG. 3, a defrosting cycle timer that counts the defrosting cycle time regardless of the end of the off-cycle defrosting operation is provided, and a predetermined defrosting cycle time is provided. A signal for instructing the defrosting operation is output to the defrosting operation control unit every time.

  According to such a configuration, the defrosting operation can be surely performed every predetermined time regardless of the defrosting operation time obtained by adding the precooling operation time and the off-cycle defrosting operation time for each time.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.
This embodiment is different from the first embodiment in that when the off-cycle defrosting operation is continuously operated for a predetermined time limit T _r , the cooling device 26 is switched to a heating defrosting operation in which the cooler 26 is heated by a defrosting heater. . Since other configurations are the same as those in the first embodiment, the description thereof is omitted.

The cooler 26 is equipped with a defrost heater (not shown) such as a sheathed heater. The defrosting operation control unit 32 is provided with a heater control unit. As shown in FIG. 7, the heater control unit performs the off cycle defrosting operation after a time limit _Tr after the start of the off cycle defrosting operation. When the operation is continued, the off-cycle defrosting operation is terminated and switched to the heater defrosting operation. The time limit _Tr after the start of the off-cycle defrosting operation is counted by the heater switching timer.

The heater defrosting operation is performed by energizing the defrosting heater and heating the cooler 26 with the compressor 21 and the internal fan 29 stopped as shown in FIG. The defrost water in which the frost has melted is discharged out of the storage body 11 through a drain pan (not shown). In this way, the defrosting of condenser 26 is performed, the cooler the temperature t _e reaches a predetermined value β is higher by the heater end temperature t ₃ than the defrosting ending temperature t _2, considered defrosting has ended First, energization of the defrosting heater is cut off, and after a predetermined draining time, the compressor 21 and the internal fan 29 are driven, and the cooling operation is restarted.

Then, the effect | action of this embodiment is demonstrated.
When the defrost cycle time _Td elapses during the cooling operation (“YES” in step S31), the off-cycle defrost operation (“YES” in step S32) is performed according to the amount of frost formation as in the first embodiment. Whether the cooling operation is continued (“NO” in step S32, “YES” in step S34, step S35), or whether the pre-cooling operation is newly started (“NO” in step S32), “NO” in step S34 ”, Step S36), whether to switch from the pre-cooling operation to the off-cycle defrosting operation (“ YES ”in Step S37, Step S33) is determined. When the duration of the off-cycle defrosting operation reaches the limit time _Tr (“YES” in step S40), it is determined that the amount of frost on the cooler 26 is large, and the off-cycle defrosting operation is terminated. The heater defrosting operation is started (step S41). When it is determined that the defrosting of the cooler 26 is completed by the off-cycle defrosting operation or the combination of the off-cycle defrosting operation and the heater defrosting operation (“YES” in step S43 or “YES” in step S42). ), These defrosting operations are terminated (step S44). And simultaneously with completion | finish of a defrost operation, a defrost cycle timer is reset and the count of the defrost cycle time _Td is newly started (step S30). In this way, the above operation is repeated every defrost cycle time _Td , and a defrosting operation according to the amount of frost on the cooler 26 is performed.

  Thus, by combining the heater defrosting operation with the off-cycle defrosting operation, even when the amount of frost formation on the cooler 26 is particularly large, the time required for the defrosting can be suppressed, and the defrosting is being performed. Cooling failure such as adversely affecting the stored items in the storage 12 due to an increase in the internal temperature t of the storage can be suppressed. Moreover, since defrosting including the indoor unit 14 of the circumference | surroundings can be performed by performing heat defrosting, a defrosting defect can be suppressed further. As an aspect of the present embodiment, FIG. 7 shows a timing chart when the cooling operation is stopped at the time of defrost cycle timer UP. As in the first embodiment, the cooling operation is performed at the time of defrost cycle timer UP. If it is in the middle, the pre-cooling operation is performed by continuing the cooling operation as in FIG.

  Although the second embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and for example, the following modifications may be included. In the following modified examples, the same members as those in the above embodiment are denoted by the same reference numerals as those in the above embodiment, and description thereof is omitted.

[Modification 1 of Embodiment 2]
A first modification of the second embodiment will be described. This modification is different from the second embodiment in that the heating defrosting operation that is switched after the time limit _Tr after the off-cycle defrosting operation is not performed by the defrosting heater, and hot gas from the compressor 21 is supplied to the cooler. The place to defrost is different.

  This hot gas defrosting operation is performed by opening a solenoid valve (closed during cooling operation) provided in a pipeline bypassed from the discharge side of the compressor 21 to the outlet side of the condenser 22. By supplying hot gas from the machine 21 to the cooler 26, the frosting of the cooler 26 is melted and defrosted by the heat generated from the inside of the cooler 26.

  Thus, by performing the hot gas defrosting operation instead of the heater defrosting operation, the time of the entire defrosting operation can be shortened as in the second embodiment, and the internal temperature rise during the defrosting can be shortened. Cooling failure due to can be suppressed. Moreover, by using the hot gas from the compressor 21, power consumption can be suppressed and energy saving can be achieved compared to using a defrost heater.

<Related technology 1>
Next, the related technique 1 will be described with reference to FIG. In this related technique 1, as in the first embodiment, when the defrost cycle timer 40 that counts the defrost cycle time _Td is UP, the operation / stop state of the cooling device 20 is detected by the cooling operation state detection unit 35, When the cooling operation is in progress, the cooling operation is continued. When the cooling operation is stopped, the pre-cooling operation is newly started. Then, the inside temperature t is reached the defrost start temperature t _1, the termination is continued cooling operation and pre cooling operation, off-cycle defrosting operation is started. In addition, the temperature difference calculation part 33 of Embodiment 1 and the defrost operation forced start part 34 shall not be provided.

According to such a configuration, similarly to Embodiment 1, since the internal temperature t at the start off cycle defrosting operation can be made uniform defrosting start temperature t _1, the time and during take off cycle defrost by setting the defrost start temperature t ₁ in consideration of the temperature range to be raised to, to suppress the cooling defects such as adverse effects on-compartment temperature t is stored goods increased during the off cycle defrosting time it can. Further, instead of hours prior cooling operation, by the inside temperature t is assumed to be cooled until reaching the defrosting start temperature t _1, it drops a certain amount of cooler temperature t _e before off cycle defrosting operation Can be aligned with the state. That is, the temperature distribution of the cooler 26 is likely to vary, and if defrosting is started in such a dispersed state, frost may partially remain in the cooler 26. For this reason, by making temperature distribution of the cooler 26 constant by the pre-cooling operation, it is possible to suppress the defrosting failure and prevent the cooling failure that may occur due to partial frosting.

<Related technology 2>
Next, the related technique 2 will be described with reference to FIG. Similar to the second embodiment, this related technique 2 switches to a heating defrosting operation in which the cooler 26 is heated by a defrosting heater when the off-cycle defrosting operation is continuously operated for a predetermined time limit _Tr . It is. In addition, the temperature difference calculation part 33 of Embodiment 2 and the defrost operation forced start part 34 shall not be provided.

  According to such a configuration, similarly to the second embodiment, by combining the heater defrosting operation with the off-cycle defrosting operation, even if the amount of frosting on the cooler 26 is particularly large, defrosting is performed. Such time can be suppressed, and cooling failures such as adverse effects on the stored items in the storage 12 due to the increase in the internal temperature t during defrosting can be suppressed. Moreover, since defrosting including the indoor unit 14 of the circumference | surroundings can be performed by performing heat defrosting, a defrosting defect can be suppressed further.

<Other embodiments>
The present invention 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 of the present invention.

(1) In the above embodiments, the cooling operation has been assumed to be maintained near a desired set temperature t _s by repeated operation and stopping of the compressor 21 is not limited to this, for example, the compressor The rotational speed may be varied and maintained near the set temperature. In addition to comparing the internal temperature with the set temperature, the temperature change rate of the internal temperature and the target temperature change rate stored in advance are compared to increase or decrease the rotational speed of the compressor. May be.

  (2) In each of the embodiments described above, the cooler thermistor 17 is attached to the surface of the cooler 26 in contact with the fins of the cooler 26. However, the present invention is not limited to this. For example, the refrigerant near the cooler outlet side The temperature of the piping may be detected and used as the temperature of the cooler.

(3) In each of the above-described embodiments, the case where the defrosting operation is performed every predetermined defrosting cycle time _Td is illustrated, but the present invention is not limited to this, for example, when the heat insulating door is opened and closed a certain number of times or more. It may be configured that a defrosting start signal is output by judging the attachment of frost from the usage state of the cooling storage.

  (4) In the above-described second embodiment, as in the first modification of the first embodiment, the end of the pre-cooling operation is not controlled by the internal temperature t, but may be controlled by a predetermined pre-cooling operation time. Good. Moreover, similarly to the modification 2 of Embodiment 1, the defrost cycle timer which counts a defrost cycle time independently is provided independently of completion | finish of a defrost operation, and defrost is carried out for every predetermined defrost cycle time. The structure which outputs the signal which instruct | indicates a driving | operation to a defrost operation control part may be sufficient. Thus, even when Embodiment 2 is changed, the same effect as Modification 1 or Modification 2 of Embodiment 1 is exhibited.

(5) In Embodiment 2 described above, although the entire defrosting operation condenser temperature t _e was complete when it reaches the defrost completion temperature t ₂ or the heater end temperature t _3, not limited to this, off Either or both of the cycle defrosting operation and the heating defrosting operation may be controlled by a predetermined time. If it switches to heating defrost operation without waiting for time limit _Tr , compared with off cycle defrost operation, although there is a fault that the temperature in a warehouse tends to rise, defrost time can be shortened, It is possible to suppress the cooling failure and the defrosting failure while considering the balance between the internal cooling and the defrosting of the cooler.

(6) In Embodiment 2 described above, after the time limit _{Tr has} elapsed from the start of the off-cycle defrosting operation, the heater switching timer is used to switch to the heater defrosting operation. It may be one that can be manually switched from the frost operation to the heater defrost operation by a changeover switch or the like.

  (7) In each embodiment described above, the prefabricated refrigerator is exemplified as the cooling storage. However, the present invention is not limited to the prefabricated refrigerator, and includes a commercial refrigerator, the freezer, the freezer refrigerator and the like. It can be applied to all cooling storages.

DESCRIPTION OF SYMBOLS 10 ... Prefabricated refrigerator (cooling storage) 11 ... Refrigerator main body 12 ... Storage 13 ... Indoor unit 14 ... Outdoor unit 16 ... Inside thermistor 17 ... Cooler thermistor 20 ... Cooling device 21 ... Compressor 22 ... Condenser 25 ... Expansion valve 26 DESCRIPTION OF SYMBOLS ... Cooler 27 ... Refrigerant piping 29 ... Inside fan 30 ... Operation control part 31 ... Cooling operation control part 32 ... Defrost operation control part 33 ... Temperature difference calculation part 34 ... Defrost operation forced start part 35 ... Cooling operation state detection part 40 ... defrost cycle timer t ... inside temperature t e _... cooler temperature t s _... set temperature t _(ON) ... ON temperature t _(OFF) ... OFF temperature t _{fs ...} forced start reference value t 1 _... defrosting start Temperature t ₂ ... Defrosting end temperature Δt, Δt _p ... Temperature difference T _d ... Defrost cycle time

Claims (2)

A storage for storing the storage;
A cooling device comprising a cooler for cooling the inside of the storage;
An internal fan that circulates the internal air cooled by heat exchange with the cooler in the storage;
An internal thermistor for detecting the internal temperature of the storage;
A cooler thermistor for detecting the temperature of the cooler;
A cooling operation control unit that performs a cooling operation to maintain the internal temperature near a preset temperature by operating the cooling device and the internal fan;
When receiving a defrost start signal, a pre-cooling operation for cooling the inside of the storage, followed by a defrosting operation control unit for performing a defrosting operation for removing frost formation of the cooler,
The defrosting operation control unit is configured to calculate a temperature difference between the internal temperature and the temperature of the cooler, and when receiving the defrosting start signal or during the precooling operation, A defrosting operation forcibly starting unit that compares the temperature difference calculated by the temperature difference calculating unit with a predetermined reference value and forcibly starts the defrosting operation on condition that the temperature difference exceeds the reference value. And a cooling storage. The defrosting operation control unit includes a cooling operation state detection unit that detects whether the cooling device is in a cooling operation state or a stopped state when receiving the defrosting start signal,
If the operation state of the cooling device detected by the cooling operation state detection unit is the cooling operation, the cooling operation is continued, and if the operation state is stopped, a pre-cooling operation is newly performed. The cooling storage according to claim 1, wherein the cooling operation is started and the continuous cooling operation and the pre-cooling operation are terminated when the internal temperature reaches a predetermined defrosting start temperature.

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