JP4935480B2 - Cooling system - Google Patents

Description

  The present invention relates to a cooling device, and more specifically, evaporates refrigerant supplied to an evaporator disposed therein, cools air passing therethrough, and introduces cooled air to cool the inside of a storage chamber. A normal defrosting process for the purpose of completely removing frost adhering to the evaporator, and a frost that is shorter than the normal defrosting process and does not change the internal temperature of the storage chamber. It is related with the cooling device provided with the control means which controls the simple defrost process which removes.

  FIG. 13 is a side view showing a general showcase in partial cross section. As shown in FIG. 13, the showcase is an open showcase 100 having no glass door on the front surface, and a main body cabinet 100 a formed as a substantially rectangular heat insulating housing having an open front surface and a product display shelf 500 are arranged. The storage chamber 400 provided, the inner duct 200 and the outer duct 300, and the evaporator 130 installed in the inner duct 200 are provided. The inner duct 200 and the outer duct 300 are formed in such a manner that the bottom wall 400a, the rear wall 400b, and the top wall 400c of the storage chamber 400 communicate with each other. The evaporator 130 is connected to the expansion valve 120 and the refrigerator 110 through a pipe. Although not explicitly shown in the figure, the refrigerator 110 includes a compressor and a condenser. The compressor compresses the supplied refrigerant. The condenser cools and condenses the refrigerant compressed by the compressor. The expansion valve 120 has a function of adiabatic expansion of the refrigerant supplied from the condenser to a low pressure state by a throttling effect and a function of adjusting a flow rate according to a change in internal temperature. The evaporator 130 evaporates the refrigerant adiabatically expanded by the expansion valve 120.

  In the open showcase 100 having the above-described configuration, the high-temperature and high-pressure refrigerant condensed in the condenser is sent out through a pipe, is adiabatically expanded to a low-temperature and low-pressure state by the expansion valve 120, and is sent out to the evaporator 130. To evaporate the refrigerant. By evaporating the refrigerant in the evaporator 130, heat is transferred from the air around the evaporator 130 to the refrigerant to cool the air. That is, the air is cooled by removing heat from the air around the evaporator 130. The refrigerant evaporated in the evaporator 130 is sent to the compressor of the refrigerator 110 through the suction pipe.

  The air cooled by the evaporator 130 is blown out from the outlet 200b toward the lower side of the storage chamber 400 through the inner duct 200 by operating a blower fan (not shown) provided in the inner duct 200. An air curtain is formed, sucked from the suction port 200a, and again sent to the evaporator 130 through the inner duct 200. The air circulating through the inner duct 200 and the storage chamber 400 in this manner cools the products placed on the product display shelf 500 in the storage chamber 400 while circulating as cold air.

  In the open showcase 100, frost adheres to the surface of the evaporator 130 (frost formation) during the cooling operation, and grows with time. For this reason, the heater 150 is periodically energized to perform defrosting. This defrosting operation is performed according to the following procedure.

  First, the supply of the refrigerant is stopped, and then the heater 150 installed on the windward side, ie, the air inlet side, below the evaporator 130 is energized to melt the frost, and the upper part of the evaporator 130, ie, the air passing therethrough. When the air temperature sensor S installed in the vicinity of the leeward side detects that the temperature is higher than the reference temperature, the heater 150 is de-energized, and air is blown for a certain period of time to drain the evaporator 130, and then cooled. Resume operation.

  Since this periodic defrosting usually takes about 30 minutes, when this defrosting is frequently performed, the temperature in the open showcase 100 is increased and the freshness of the product is lowered. Therefore, a defrost with a short time (hereinafter referred to as “simple defrost”) between the operation of the above-described periodic defrost (hereinafter referred to as “normal defrost”) and the next operation. Patent Document 1 and Patent Document 2 disclose an open showcase 100 having a defrosting system for performing the above. This simple defrosting is performed by energizing the heater 150 installed in the lower part of the evaporator 130 after stopping the supply of the refrigerant as in the case of the normal defrosting. The energization time is as short as about 5 minutes, and after the energization of the heater 150 is stopped, the cooling operation is immediately resumed without blowing air for draining water. Therefore, although the temperature in a store | warehouse | chamber rises temporarily by performing simple defrost, since it is a short time, temperature does not become high like normal defrost, and it affects the freshness of the goods of the storage chamber 400. There is nothing. By performing this simple defrosting several times between the normal defrosting operation and the next operation, frost adhering to the evaporator 130 can be reduced, and the operation cycle of normal defrosting is long. It becomes possible to make it.

Japanese Unexamined Patent Publication No. 7-190582 JP 2000-81272 A

  By the way, in the above-described open showcase 100, it is normal based on the temperature detected only by the air temperature sensor S provided at the position on the leeward side of the evaporator 130, that is, at the position farther than the heater 150 installed on the windward side. Since defrosting was performed, there were the following problems.

  During normal defrosting or simple defrosting, the frost attached to the evaporator 130 is melted by blowing air heated by the heater 150. However, when the air heated by the heater 150 is blown, the frost attached to the evaporator 130 is not uniformly melted, but the frost attached to the portion adjacent to the heater 150 is melted most. The frost attached to the part farthest from the heater 150, that is, the part on the leeward side of the evaporator 130 is not easily melted. Also, frost adhering to the upper ends of both ends of the evaporator 130, which is also a portion far from the heater 150, is not easily melted. That is, uneven frost formation occurs. When normal defrosting is performed in a state where such uneven frost formation has occurred, the frost adhering to the portion adjacent to the heater 150 is actively melted, and the air heated by the heater 150 is converted into the air temperature sensor S. As a result of being detected by the air temperature sensor S as being above the reference temperature by passing through the vicinity, it is assumed that the defrosting is completed even if the frost far from the heater 150 as described above is not melted. There was a risk of termination. If the frost is not melted and melts in this way, the remaining frost generates ice that is very difficult to melt, called an ice bank.

  In order to suppress the occurrence of such an ice bank, the reference temperature for determining the end of energization of the heater 150 can be set higher. However, this may increase the internal temperature. .

  In view of the above circumstances, an object of the present invention is to provide a cooling device that can suppress the generation of an ice bank without causing an increase in internal temperature.

In order to achieve the above object, a cooling device according to claim 1 of the present invention evaporates a refrigerant supplied to an evaporator disposed therein, cools air passing therethrough, and introduces the cooled air. The inside of the storage chamber is cooled by a normal defrosting process for the purpose of completely removing the frost attached to the evaporator, and in a shorter time than the normal defrosting process, and the storage An air temperature sensor for detecting an air temperature on the lee side of the evaporator, a cooling device comprising a control means for controlling a simple defrosting process for removing frost so that the internal temperature of the chamber does not change, and the evaporation A refrigerant temperature sensor for detecting the temperature of the refrigerant supplied to the evaporator in the vicinity of the refrigerant inlet located on the leeward side of the evaporator in the refrigerant introduction pipe for introducing the refrigerant into the evaporator, and the windward side of the evaporator Heating means for heating the air And the control means stops the supply of the refrigerant to the evaporator and drives the heating means when performing the normal defrosting process, and the air temperature detected by the air temperature sensor is determined in advance. When the temperature of the refrigerant detected by the refrigerant temperature sensor is equal to or higher than a predetermined second reference temperature lower than the first reference temperature , the driving of the heating unit is stopped. On the other hand, when the simple defrosting process is performed, the supply of the refrigerant to the evaporator is stopped and the heating unit is driven to start the supply of the refrigerant when a predetermined time has elapsed. At the same time, the driving of the heating means is stopped.

Further, the cooling device according to claim 2 of the present invention evaporates the refrigerant supplied to the evaporator disposed therein, cools the air passing therethrough, introduces the cooled air, and introduces the inside of the storage chamber. A normal defrosting process for the purpose of completely removing the frost attached to the evaporator, and a shorter time than the normal defrosting process, and the internal temperature of the storage chamber changes. In a cooling device comprising a control means for controlling simple defrosting processing for removing frost to such an extent that the frost is removed, an air temperature sensor for detecting an air temperature on the leeward side of the evaporator, and introducing the refrigerant into the evaporator A refrigerant temperature sensor for detecting the temperature of the refrigerant supplied to the evaporator in the vicinity of the refrigerant inlet located on the leeward side of the evaporator in the refrigerant introduction pipe, and heating for heating the air on the windward side of the evaporator And the control means In the case of performing the normal defrosting process, the supply of the refrigerant to the evaporator is stopped and the heating unit is driven, and the air temperature detected by the air temperature sensor is a first reference temperature determined in advance. drives stopping the heating means when a higher, and the care and temperature of the refrigerant detected by the refrigerant temperature sensor becomes a second reference temperature or more predetermined lower than the first reference temperature On the other hand, when the supply of the refrigerant is started, when the simple defrosting process is performed, the supply of the refrigerant to the evaporator is stopped and the heating unit is driven, and when the predetermined time has elapsed, the refrigerant And the driving of the heating means is stopped.

The cooling device according to claim 3 of the present invention is the cooling device according to claim 1 or 2 , wherein the control means includes an air temperature blown into the storage chamber, and a temperature detected by the air temperature sensor. A temperature difference calculating means for calculating a difference between the temperature difference and an average value of differences calculated by the temperature difference calculating means in a stable period from the completion of defrosting to frosting for each defrosting process as a stable value Update storage means for updating and storing; deviation calculating means for calculating a deviation of a current temperature difference with respect to a stable value stored by the update storing means; and calculating a temporal change amount of the deviation calculated by the deviation calculating means The amount of frost formation is estimated by fuzzy inference based on the temperature difference deviation calculated by the deviation calculation means, the time difference deviation calculated by the deviation calculation means, and the time variation calculated by the deviation calculation means. And a inference unit for determining the timing, characterized in providing a defrosting processing start instruction by the defrosting start timing.

  According to the cooling device of the first aspect of the present invention, when the control means performs the normal defrosting process, the supply of the refrigerant to the evaporator is stopped and the heating means is driven and detected by the air temperature sensor. The heating means is stopped when the air temperature is equal to or higher than a predetermined first reference temperature and the refrigerant temperature detected by the refrigerant temperature sensor is equal to or higher than a predetermined second reference temperature, When performing the simple defrosting process, the supply of the refrigerant to the evaporator is stopped and the heating unit is driven, and the supply of the refrigerant is started and the heating unit is stopped when a predetermined time has elapsed. Therefore, there is no unmelted frost, the generation of ice banks can be suppressed, and there is no need to increase the set temperature, so the internal temperature does not increase. Therefore, there is an effect that it is possible to suppress the generation of the ice bank without causing an increase in the internal temperature.

According to the cooling device of the second aspect of the present invention, when the control means performs the normal defrosting process, the supply of the refrigerant to the evaporator is stopped and the heating means is driven and detected by the air temperature sensor. The heating means is stopped when the temperature of the air to be discharged becomes equal to or higher than a predetermined first reference temperature, and the temperature of the refrigerant detected by the refrigerant temperature sensor becomes equal to or higher than a predetermined second reference temperature. On the other hand, when the supply of the refrigerant is started, when the simple defrosting process is performed, the supply of the refrigerant to the evaporator is stopped and the heating means is driven, and the refrigerant is supplied when a predetermined time has elapsed. The heating means is stopped and the driving means is stopped, so that there is no frost melting remaining, the generation of ice banks can be suppressed, and there is no need to increase the set temperature, so the internal temperature rises. There is no. Therefore, there is an effect that it is possible to suppress the generation of the ice bank without causing an increase in the internal temperature. In particular, since the driving of the heating means is stopped when the outlet air temperature is equal to or higher than the first reference temperature, the temperature rise during defrosting can be suppressed and damage to the product can be minimized. Become.

  Hereinafter, preferred embodiments of a cooling device according to the present invention will be described in detail with reference to the accompanying drawings.

<Embodiment 1>
FIG. 1 is a side view showing a partial cross section of an open showcase to which a cooling device according to Embodiment 1 of the present invention is applied. The cooling device illustrated here is applied to the open showcase 1 that sells a product stored inside in a cooled state. Such a cooling device may be applied to a plurality of open showcases 1. However, in the first embodiment, a cooling device applied to one open showcase 1 will be described for convenience of explanation. I will decide.

  The open showcase 1 includes a main body cabinet 1a, an inner duct 2 and an outer duct 3. The main body cabinet 1a is a substantially rectangular heat-insulating housing whose front surface is open, and has a storage chamber 4 inside. The storage chamber 4 is provided with a plurality of product display shelves 5 along the vertical direction. The inner duct 2 and the outer duct 3 are ventilation passages formed in such a manner that the bottom wall 4a, the rear wall 4b, and the top wall 4c that define the accommodation chamber 4 are communicated with each other. Is formed on the side close to. In other words, the outer duct 3 is formed on the outer side than the inner duct 2. The suction ports 2a and 3a of the inner duct 2 and the outer duct 3 are provided at the front lower end portion of the storage chamber 4, that is, the lower edge portion of the front opening of the main body cabinet 1a, while the inner duct 2 and the outer duct 3 are provided. Each of the air outlets 2b and 3b is provided at the upper end portion on the front side of the storage chamber 4, that is, the upper edge portion of the front opening of the main body cabinet 1a.

  The cooling device applied to such an open showcase 1 is configured by connecting a refrigerator 11, an expansion valve 12, and an evaporator 13 with piping. The refrigerator 11 is disposed outside the open showcase 1 and includes a compressor and a condenser, though not explicitly shown in the drawing. The compressor compresses the supplied refrigerant and supplies it to the condenser as a high-temperature and high-pressure refrigerant (gas refrigerant). The condenser radiates (condenses) the refrigerant compressed to a high temperature and high pressure by the compressor to form a high temperature and high pressure refrigerant (liquid refrigerant). The expansion valve 12 is connected to the refrigerator 11 through a pipe. The refrigerant supplied from the refrigerator 11, that is, the refrigerant condensed by the condenser (liquid refrigerant) is adiabatically expanded to cool the refrigerant at a low temperature and low pressure (liquid refrigerant). ).

  The evaporator 13 is connected to the expansion valve 12 through the refrigerant introduction pipe 14 and is disposed inside the inner duct 2. The evaporator 13 is for cooling the air passing through the inside of the inner duct 2 by evaporating the supplied refrigerant, that is, the refrigerant adiabatically expanded by the expansion valve 12. As shown in FIG. 2, the evaporator 13 in the present embodiment is a finned coil type evaporator composed of, for example, a copper pipe 13 a and an aluminum fin 13 b, and an upper side portion serves as a refrigerant inlet 13 c, and The side part is the refrigerant outlet 13d. That is, the refrigerant inlet 13c communicates with the refrigerant introduction pipe 14 inside.

  In addition, a heater 15 is disposed in the vicinity of the lower portion of the evaporator 13, and a blower fan 16 (see FIG. 3) not shown in the drawing is disposed. The heater 15 is a heating unit that is energized when a command is given from the defrost control unit 20 described later and heats the ambient air. The blower fan 16 sends air by being driven.

  The refrigerant outlet 13 d of the evaporator 13 communicates with the inside of the refrigerant outlet pipe 17, and the refrigerant outlet pipe 17 is connected to the refrigerator 11. That is, the evaporator 13 is connected to the refrigerator 11 through the refrigerant outlet pipe 17. The refrigerant (gas refrigerant) evaporated by the evaporator 13 passes through the refrigerant outlet pipe 17 and is supplied to the refrigerator 11 (compressor).

  In such a cooling device, the high-temperature and high-pressure gas refrigerant discharged from the refrigerator 11 (compressor) condenses (dissipates heat) in the condenser and becomes a high-temperature and high-pressure liquid refrigerant. This high-temperature and high-pressure liquid refrigerant is supplied to the expansion valve 12, and is adiabatically expanded by the expansion valve 12 to become a low-temperature and low-pressure gas-liquid two-phase refrigerant, and enters the refrigerant inlet 13 c of the evaporator 13 through the refrigerant outlet pipe 17. As a result, the refrigerant enters the copper pipe 13 a from the refrigerant inlet 13 c and is supplied to the evaporator 13. The gas-liquid two-phase refrigerant supplied to the evaporator 13 exchanges heat with the internal air of the storage chamber 4 supplied by the blower fan 16, and is evaporated (heat absorption) to become a low-temperature and low-pressure gas refrigerant. The chamber 4 is cooled. The gas refrigerant that has passed through the evaporator 13, that is, the gas refrigerant that has passed through the copper pipe 13 a and reached the refrigerant outlet 13 d is sucked into the refrigerator 11 (compressor) through the refrigerant outlet pipe 17.

  By the way, when the blower fan 16 is driven, the internal air that has entered the inner duct 2 from the suction port 2a (the internal air of the housing chamber 4) is cooled when passing around the evaporator 13, and then the inner duct 2 An air curtain is formed by being blown downward from the air outlet 2b, enters the inner duct 2 again from the suction port 2a, and is sent to the evaporator 13. The internal air circulating through the inner duct 2 and the storage chamber 4 in this way cools the products placed on the product display shelf 5 of the storage chamber 4 while circulating as cold air.

  On the other hand, a fan (not shown) (hereinafter referred to as an “outer fan”) is also provided in the outer duct 3, and when the outer fan is driven, the air that has passed through the outer duct 3 is blown out downward from the outlet 3b. Thus, an air curtain is formed and enters the outer duct 3 again from the suction port 3a. The air passing through the outer duct 3 is non-cold air that is not cooled by the evaporator 13 or the like, and the air curtain formed by being blown out from the outlet 3 b is an air curtain formed by the cold air circulating through the inner duct 2. It is for protecting.

  In the open showcase 1, an outlet air temperature sensor S1 is provided at a position on the leeward side in the vicinity of the evaporator 13, and an inlet refrigerant temperature sensor S2 is provided in the vicinity of the refrigerant inlet 13c of the refrigerant introduction pipe. . The outlet air temperature sensor S <b> 1 is detection means for detecting the air temperature on the leeward side of the evaporator 13, that is, the temperature of the air immediately after passing through the evaporator 13. The inlet refrigerant temperature sensor S2 is detection means for detecting the temperature in the vicinity of the refrigerant inlet 13c in the refrigerant introduction pipe 14, that is, the temperature of the refrigerant immediately before being supplied to the evaporator 13. Here, if water accumulates between the inlet refrigerant temperature sensor S2 and the refrigerant introduction pipe 14, it may grow into ice and decrease the detection accuracy, so that the contact area with the refrigerant introduction pipe 14 is reduced. It is preferable to keep the water small so that water does not accumulate.

  FIG. 3 is a block diagram showing a control system of the cooling device according to Embodiment 1 of the present invention. As shown in FIG. 3, the cooling device includes a defrost control means 20 as one of its control systems. The defrost control means 20 includes a setting storage unit 21, a time measurement unit 22, a normal defrost control unit 23, and a simple defrost control unit 24.

  The setting storage unit 21 sets various information in advance and stores them. More specifically, a target temperature (first reference temperature) of the air temperature on the leeward side of the evaporator 13 and a target temperature (second reference temperature) of the refrigerant temperature immediately before being supplied to the evaporator 13 are set in advance. And these are memorize | stored, and the draining time in the normal defrost process mentioned later and the process time of the simple defrost process mentioned later are preset and memorize | stored. In the first embodiment, for example, the first reference temperature is 7 ° C. and the second reference temperature is 0 ° C. Here, the first reference temperature and the second reference temperature are temperatures sufficient to determine that the frost attached to the evaporator 13 has been completely melted. The processing time is, for example, about 5 minutes.

  The time measuring unit 22 is for measuring time. The normal defrost control part 23 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a normal defrost process. The simple defrost control unit 24 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a simple control process.

  FIG. 4 is a flowchart showing the contents of the normal defrosting process performed by the defrosting control means shown in FIG. Hereinafter, the operation of the cooling device will be described with reference to FIG.

  First, in the normal defrosting process shown in FIG. 4, the defrost control means 20 closes the expansion valve 12 through the normal defrost control unit 23 (step S <b> 101) and energizes the heater 15 through the normal defrost control unit 23. (Step S102). By closing the expansion valve 12 in this way, the supply of the refrigerant to the evaporator 13 is stopped. Further, the air heated by the heater 15 in step S <b> 102 passes around the evaporator 13 as a result of being blown by the blower fan 16. As a result, the frost attached to the evaporator 13 is melted.

  The defrost control means 20 energized to the heater 15 detects the air temperature (outlet air temperature) on the lee side of the evaporator 13 through the outlet air temperature sensor S1, and is supplied to the evaporator 13 through the inlet refrigerant temperature sensor S2. The temperature of the refrigerant (inlet refrigerant temperature) is detected (step S103).

  Then, the defrost control means 20 determines whether the outlet air temperature is equal to or higher than the first reference temperature stored in the setting storage unit 21 through the normal defrost control unit 23 (step S104), and the outlet air temperature is determined. When the temperature is lower than the first reference temperature (step S104: No), the process of step S103 is performed. On the other hand, when the outlet air temperature is equal to or higher than the first reference temperature (step S104: Yes), the inlet refrigerant It is determined whether or not the temperature is equal to or higher than the second reference temperature stored in the setting storage unit 21 (step S105).

  When the inlet refrigerant temperature is lower than the second reference temperature (step S105: NO), the process of step S103 is performed, while when the inlet refrigerant temperature is equal to or higher than the second reference temperature (step S105: Yes). Stops the energization of the heater 15 through the normal defrost control unit 23, that is, stops the driving of the heater 15 (step S106), and simultaneously starts time measurement through the time measurement unit 22 (step S107). By stopping the driving of the heater 15 in step S106, removal of water generated by melting from frost melting, so-called draining, is started.

  Then, it is determined whether or not the measurement time started in step S108 has passed the predetermined time, that is, the draining time stored in the setting storage unit 21 (step S108), and when the draining time has elapsed (step S108). : Yes), the expansion valve 12 is opened through the normal defrost control unit 23 (step S109), the current process is terminated, and the procedure is returned. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  FIG. 5 is a flowchart showing the contents of the simple defrosting process performed by the defrosting control means shown in FIG. Hereinafter, the operation of the cooling device will be further described with reference to FIG.

  First, in the simple defrost process shown in FIG. 5, the defrost control means 20 closes the expansion valve 12 through the simple defrost control part 24 (step S201). As a result, the supply of the refrigerant to the evaporator 13 is stopped.

  Next, the defrost control means 20 energizes and drives the heater 15 through the simple defrost control unit 24 (step S202), and simultaneously starts time measurement through the time measurement unit 22 (step S203). Here, as a result of the air heated by the heater 15 being blown by the blower fan 16, the air passes around the evaporator 13. As a result, the frost attached to the evaporator 13 is melted.

  Then, it is determined whether or not the measurement time started in step S203 has passed a predetermined time, that is, the processing time stored in the setting storage unit 21 (step S204), and when the processing time has passed (step S204). : Yes), the energization of the heater 15 is stopped through the simple defrost control unit 24, that is, the drive of the heater 15 is stopped, the expansion valve 12 is opened (step S205), and the current process is terminated. To return. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  In the cooling device according to Embodiment 1 of the present invention as described above, in the normal defrosting process, when the outlet air temperature is equal to or higher than the first reference temperature and the inlet refrigerant temperature is equal to or higher than the second reference temperature, the heater 15 is stopped, that is, the frost attached to the evaporator 13 is completely melted when the outlet air temperature is equal to or higher than the first reference temperature and the inlet refrigerant temperature is equal to or higher than the second reference temperature. Therefore, the driving of the heater 15 is stopped. More specifically, the fact that the outlet air temperature becomes equal to or higher than the first reference temperature means that at least the heat heated by the heater 15 passes through the evaporator 13, and the passage of air is frost. It means that it is not hindered. In addition, the fact that the inlet refrigerant temperature is equal to or higher than the second reference temperature means that the frost has melted even at the position where the frost is most likely to remain unmelted.

  In the conventional normal defrosting described above, since the determination was made based only on the outlet air temperature, it was possible to determine that the frost had melted to such an extent that the passage of air was not hindered, but the frost was not completely melted. In some cases, the unmelted frost may grow before the next defrosting process, and the cooling capacity of the evaporator 13 may be reduced.

  Thus, according to the cooling device in Embodiment 1 of the present invention, in the normal defrosting process, when the outlet air temperature is equal to or higher than the first reference temperature and the inlet refrigerant temperature is equal to or higher than the second reference temperature, the heater 15 is stopped, and in the simple defrosting process, it is forcibly terminated when a predetermined processing time has elapsed, so there is no remaining frost melting and the generation of ice banks can be suppressed. Moreover, since it is not necessary to increase the set temperature, the internal temperature does not increase. Therefore, the occurrence of ice banks can be suppressed without causing an increase in internal temperature. In particular, by performing the simple defrosting process, the number of times of the normal defrosting process can be reduced, and thereby the damage given to the product stored in the storage chamber 4 can be reduced.

<Embodiment 2>
FIG. 6 is a block diagram showing a control system of the cooling device according to Embodiment 2 of the present invention. In the following description, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  As shown in FIG. 6, the cooling device includes defrost control means 30 as one of its control systems. The defrost control means 30 includes a setting storage unit 31, a time measurement unit 32, a normal defrost control unit 33, and a simple defrost control unit 34.

  The setting storage unit 31 sets various information in advance and stores them. More specifically, a target temperature (first reference temperature) of the air temperature on the leeward side of the evaporator 13 and a target temperature (second reference temperature) of the refrigerant temperature just before being supplied to the evaporator 13 are set in advance. And while memorize | storing these, the draining time in the normal defrost process mentioned later and the process time of the simple defrost process mentioned later are preset and memorize | stored. In the second embodiment, for example, the first reference temperature is 7 ° C. and the second reference temperature is 0 ° C. Here, the first reference temperature and the second reference temperature are temperatures sufficient to determine that the frost attached to the evaporator 13 has been completely melted. The processing time is, for example, about 5 minutes.

  The time measuring unit 32 is for measuring time. The normal defrost control unit 33 is for controlling the drive of the expansion valve 12 and the heater 15 when performing the normal defrost process. The simple defrost control part 34 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a simple control process.

  FIG. 7 is a flowchart showing the contents of the normal defrosting process performed by the defrosting control means shown in FIG. Hereinafter, the operation of the cooling device will be described with reference to FIG.

  First, in the normal defrosting process shown in FIG. 7, the defrosting control means 30 closes the expansion valve 12 through the normal defrosting control unit 33 (step S <b> 301) and energizes the heater 15 through the normal defrosting control unit 33. To drive (step S302). By closing the expansion valve 12 in this way, the supply of the refrigerant to the evaporator 13 is stopped. Further, the air heated by the heater 15 in step S <b> 302 passes around the evaporator 13 as a result of being blown by the blower fan 16. As a result, the frost attached to the evaporator 13 is melted.

  The defrost control means 30 energized to the heater 15 detects the air temperature (outlet air temperature) on the leeward side of the evaporator 13 through the outlet air temperature sensor S1 (step S303).

  Then, the defrost control means 30 determines whether or not the outlet air temperature is equal to or higher than the first reference temperature stored in the setting storage unit 31 through the normal defrost control unit 33 (step S304). When the temperature is lower than the first reference temperature (step S304: No), the process of step S303 is performed. On the other hand, when the outlet air temperature is equal to or higher than the first reference temperature (step S304: Yes), the normal removal is performed. The energization of the heater 15 is stopped through the frost control unit 33, that is, the driving of the heater 15 is stopped (step S305).

  The defrosting control means 30 that stopped driving the heater 15 detects the temperature of the refrigerant (inlet refrigerant temperature) supplied to the evaporator 13 through the inlet refrigerant temperature sensor S2 (step S306), and then the normal defrost control unit. 33, it is determined whether the inlet refrigerant temperature is equal to or higher than the second reference temperature stored in the setting storage unit 31 (step S307). If the inlet refrigerant temperature is lower than the second reference temperature (step S307: No) In step S306, the process of step S306 is performed. On the other hand, when the inlet refrigerant temperature is equal to or higher than the second reference temperature (step S307: Yes), the expansion valve 12 is opened (step S308), and the current process is performed. Finish and return the procedure. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  FIG. 8 is a flowchart showing the contents of the simple defrosting process performed by the defrosting control means shown in FIG. Hereinafter, the operation of the cooling device will be further described with reference to FIG.

  First, in the simple defrost process shown in FIG. 8, the defrost control means 30 closes the expansion valve 12 through the simple defrost control part 34 (step S401). As a result, the supply of the refrigerant to the evaporator 13 is stopped.

  Next, the defrost control means 30 energizes and drives the heater 15 through the simple defrost control part 34 (step S402), and simultaneously starts time measurement through the time measurement part 32 (step S403). Here, as a result of the air heated by the heater 15 being blown by the blower fan 16, the air passes around the evaporator 13. As a result, the frost attached to the evaporator 13 is melted.

  Then, it is determined whether or not the measurement time started in step S403 has passed a predetermined time, that is, the processing time stored in the setting storage unit 31 (step S404), and when the processing time has passed (step S404). : Yes), the energization of the heater 15 is stopped through the simple defrosting control unit 34, that is, the drive of the heater 15 is stopped, and the expansion valve 12 is opened (step S405), and the current process is terminated, and the procedure To return. Thereby, supply of the refrigerant | coolant with respect to the evaporator 13 is started.

  In the cooling device according to the second embodiment of the present invention as described above, in the normal defrosting process, the driving of the heater 15 is stopped when the outlet air temperature is equal to or higher than the first reference temperature. This means that at least the heat heated by the heater 15 passes through the evaporator 13 as described above, and means that the passage of air is not hindered by frost. Then, after the heater 15 stops driving, the expansion valve 12 is opened when the inlet refrigerant temperature is equal to or higher than the second reference temperature. Even if the driving of the heater 15 is stopped, warm air can be blown by the blower fan 16, whereby the frost attached to the evaporator 13, particularly the refrigerant introduction pipe 14 is melted.

  That is, in the normal defrosting process, since the driving of the heater 15 is stopped when the outlet air temperature is equal to or higher than the first reference temperature, the heater 15 is driven faster than the first embodiment described above. Can be stopped. Further, since the expansion valve 12 is closed until the inlet refrigerant temperature becomes equal to or higher than the second reference temperature, the frost attached to the position where the frost is most likely to be melted is completely melted.

  Thus, according to the cooling device in Embodiment 2 of the present invention, in the normal defrosting process, when the outlet air temperature is equal to or higher than the first reference temperature, the driving of the heater 15 is stopped and the inlet refrigerant temperature is The expansion valve 12 is opened when the temperature is equal to or higher than 2 reference temperature, and in the simple defrosting process, it is forcibly terminated when a predetermined processing time elapses. Can be suppressed, and there is no need to increase the set temperature, so the internal temperature does not rise. Therefore, the occurrence of ice banks can be suppressed without causing an increase in internal temperature. In particular, since the driving of the heater 15 is stopped when the outlet air temperature is equal to or higher than the first reference temperature, the temperature rise during defrosting can be suppressed as compared with the case of the first embodiment. It is possible to minimize the damage to the. Moreover, by performing the simple defrosting process, the number of times of the normal defrosting process can be reduced, and the damage given to the product stored in the storage chamber 4 can also be reduced.

  In the second embodiment, in step S307 and step S308, the expansion valve 12 is opened depending on whether or not the inlet refrigerant temperature is equal to or higher than the second reference temperature. However, the present invention is not limited to this and is determined in advance. Depending on whether or not the given time has elapsed, the expansion valve may be opened to start supplying the refrigerant to the evaporator.

<Embodiment 3>
FIG. 9 is a block diagram showing a control system of the cooling device according to Embodiment 3 of the present invention. In the following description, the same components as those in the first embodiment described above are denoted by the same reference numerals, and the description thereof is omitted as appropriate.

  As shown in FIG. 9, the cooling device includes a defrost control means 20 'as one of its control systems. The defrost control means 20 ′ includes a setting storage unit 21, a time measurement unit 22, a normal defrost control unit 23, a simple defrost control unit 24, and a defrost start determination unit 40.

  The defrosting start determining means 40 obtains the defrosting start timing and gives a defrosting start command. As shown in FIG. 10, the air temperature difference calculating unit 41, the deviation calculating unit 42, and the change amount calculating unit. 43, an elapsed time measuring unit 44 after defrosting, a time difference calculating unit 45, a defrosting interval calculating unit 46, a fuzzy inference unit 47, a membership function 48, and a rule unit 49.

  The air temperature difference calculation unit 41 is a difference (T1-T2) between the temperature detected by the blowing air temperature sensor S3 (blowing air temperature T1) and the temperature detected by the outlet air temperature sensor S1 (outlet air temperature T2). Is calculated. Here, the blowout air temperature sensor S3 is disposed in the housing chamber 4 in the vicinity of the blowout port 2b of the inner duct 2, and detects the temperature of the blown air from the blowout port 2b (the temperature of the blown air). It is.

  The deviation calculating unit 42 calculates a deviation ΔT with respect to the stable value T0 of the open showcase 1 for the temperature difference (T1-T2) calculated through the air temperature difference calculating unit 41. Here, the stable value T0 is a unique value obtained during the normal defrosting of the open showcase 1. That is, when the normal defrosting is started, the blown air temperature and the outlet air temperature rise once and then fall and stabilize. Usually, it takes about 2 hours to stabilize, and then it is kept constant for about 1 hour until frosting starts. The temperature difference (T1-T2) during this period is taken in each time of normal defrosting, and the moving average is set as the stable value T0.

  The change amount calculation unit 43 calculates a temporal change amount dT of the deviation ΔT calculated through the deviation calculation unit 42.

  The post-defrosting elapsed time measuring unit 44 measures the elapsed time tp after the previous normal defrosting.

  The time difference calculation unit 45 calculates a time difference Δt between the elapsed time tp measured through the post-defrost elapsed time measurement unit 44 and the defrost interval reference value t0. The defrosting interval reference value t0 uses a moving average of every defrosting interval.

  The defrosting interval calculation unit 46 calculates an outdoor air enthalpy from the outside air temperature T3 detected by the outside air temperature sensor S4 and the outside air humidity H detected by the outside air humidity sensor S5, and calculates the optimum dehumidifying interval value ta. It is. Here, the outside air temperature sensor S4 and the outside air humidity sensor S5 are installed around the open showcase 1.

  In the time difference calculation unit 45, when defrosting is performed for the first time, the time difference Δt is calculated using the optimum dehumidification interval value ta calculated through the defrost interval calculation unit 46 as the defrost interval reference value t0.

  The fuzzy inference unit 47 determines the presence or absence of defrosting by fuzzy inference based on each input data, that is, the deviation ΔT, the temporal change amount dT, and the time difference Δt. Specifically, the fuzzy inference unit 47 determines the presence / absence of defrosting based on each input data and the rules set in the rule unit 49. While giving a defrost start command to the simple defrost control part 24, when a normal defrost is required, a normal defrost start command is given to the normal defrost control part 23. FIG.

  The membership function 48 indicates how much frost is attached to each data input to the fuzzy inference unit 47, that is, the deviation ΔT, the temporal change amount dT, and the time difference Δt, or how much room is left before the defrosting. It is used to judge the margin or irrationality.

  The rule unit 49 defines rules for determining the presence or absence of defrosting in the fuzzy reasoning unit 47. Specifically, it is a rule of know-how regarding defrosting control possessed by a professional engineer for the open showcase 1 as shown in FIG. 11, and when the deviation ΔT increases, the defrosting starts and the deviation ΔT decreases. In this case, the defrosting start is determined when the time difference Δt increases, the defrosting start is determined when the temporal change dT increases.

  FIG. 12 is a flowchart showing the contents of the defrosting start determination process performed by the defrosting control means shown in FIG. Hereinafter, the operation of the cooling device will be described with reference to FIG.

  In the defrost start determining process, the defrost start determining means 40 in the defrost control means 20 ′ detects the blown air temperature T1 through the blown temperature sensor S3 and detects the outlet air temperature T2 through the outlet air temperature sensor S1 (step). S501).

  The defrosting start determining means 40 that has detected the blown air temperature T1 and the outlet air temperature T2 calculates a temperature difference (T1-T2) through the air temperature difference calculating unit 41 (step S502), and then air through the deviation calculating unit 42. A deviation ΔT with respect to the stable value T0 of the open showcase 1 is calculated for the temperature difference (T1-T2) calculated by the temperature difference calculation unit 41 (step S503).

  The defrosting start determination means 40 that has calculated the deviation ΔT calculates the temporal change amount dT of the deviation ΔT calculated by the deviation calculation unit 42 through the change amount calculation unit 43 (step S504). The defrosting start determining means 40 that has calculated the temporal change amount dT measures the elapsed time tp from the previous normal defrosting through the post-defrosting elapsed time measuring unit 44 (step S505), and the time difference calculating unit 45. The time difference Δt between the elapsed time tp measured by the post-defrost elapsed time measuring unit 44 and the defrost interval reference value t0 is calculated (step S506).

  Then, the defrosting start determining means 40 determines the presence or absence of defrosting by fuzzy inference based on the deviation ΔT, the temporal change amount dT, and the time difference Δt input through the fuzzy inference unit 47 (step S507), and performs the current process. Finish and return the procedure.

  As described above, according to the cooling device in the third embodiment of the present invention, the start timing of the simple defrosting and the normal defrosting can be performed by the defrost start determining means 40 by fuzzy control, and the simple defrosting can be performed. The frost treatment and the normal defrost treatment can be minimized. Therefore, since the frequency | count of raising the internal temperature of the storage chamber 4 can be reduced, it becomes possible to minimize the damage given to goods.

  As described above, the cooling device of the present invention evaporates the refrigerant supplied to the evaporator disposed therein, cools the air passing therethrough, and introduces the cooled air to cool the inside of the storage chamber. Useful for.

FIG. 1 is a side view showing a partial cross section of an open showcase to which a cooling device according to Embodiment 1 of the present invention is applied. FIG. 2 is a perspective view showing the evaporator shown in FIG. FIG. 3 is a block diagram showing a control system of the cooling device according to Embodiment 1 of the present invention. FIG. 4 is a flowchart showing the contents of the normal defrosting process performed by the defrosting control means shown in FIG. FIG. 5 is a flowchart showing the contents of the simple defrosting process performed by the defrosting control means shown in FIG. FIG. 6 is a block diagram showing a control system of the cooling device according to Embodiment 2 of the present invention. FIG. 7 is a flowchart showing the contents of the normal defrosting process performed by the defrosting control means shown in FIG. FIG. 8 is a flowchart showing the contents of the simple defrosting process performed by the defrosting control means shown in FIG. FIG. 9 is a block diagram showing a control system of the cooling device according to Embodiment 3 of the present invention. FIG. 10 is a block diagram showing the defrosting start determining means shown in FIG. FIG. 11 is a chart showing an example of rules defined in the rule part. FIG. 12 is a flowchart showing the contents of the defrosting start determination process performed by the defrosting control means shown in FIG. FIG. 13 is a side view showing a general showcase in partial cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Open showcase 4 Accommodating room 11 Refrigerator 13 Evaporator 15 Heater 16 Blower fan 20, 30 Defrost control means 21, 31 Setting storage part 22, 32 Time measurement part 23, 33 Normal defrost control part 24, 34 Simple removal Frost control part S1 Outlet air temperature sensor S2 Inlet refrigerant temperature sensor

Claims (3)

The refrigerant supplied to the evaporator disposed therein is evaporated to cool the air passing therethrough, the cooled air is introduced to cool the inside of the storage chamber, and the frost adhered to the evaporator A normal defrosting process for the purpose of completely removing the frost and a simple defrosting process for removing the frost in a shorter time than the normal defrosting process and to the extent that the internal temperature of the storage chamber does not change. In a cooling device provided with a control means for controlling,
An air temperature sensor for detecting an air temperature on the leeward side of the evaporator;
A refrigerant temperature sensor for detecting the temperature of the refrigerant supplied to the evaporator in the vicinity of the refrigerant inlet located on the leeward side of the evaporator in the refrigerant introduction pipe for introducing the refrigerant into the evaporator;
Heating means for heating the air on the windward side of the evaporator,
In the case of performing the normal defrosting process, the control unit stops the supply of the refrigerant to the evaporator and drives the heating unit, and the air temperature detected by the air temperature sensor is determined in advance. While the temperature of the refrigerant detected by the refrigerant temperature sensor is equal to or higher than the first reference temperature and higher than a predetermined second reference temperature lower than the first reference temperature , the heating unit is stopped. In the case where the simple defrosting process is performed, the supply of the refrigerant to the evaporator is stopped and the heating unit is driven to start the supply of the refrigerant when a predetermined time elapses and A cooling device characterized in that driving of the heating means is stopped. The refrigerant supplied to the evaporator disposed therein is evaporated to cool the air passing therethrough, the cooled air is introduced to cool the inside of the storage chamber, and the frost adhered to the evaporator A normal defrosting process for the purpose of completely removing the frost and a simple defrosting process for removing the frost in a shorter time than the normal defrosting process and to the extent that the internal temperature of the storage chamber does not change. In a cooling device provided with a control means for controlling,
An air temperature sensor for detecting an air temperature on the leeward side of the evaporator;
A refrigerant temperature sensor for detecting the temperature of the refrigerant supplied to the evaporator in the vicinity of the refrigerant inlet located on the leeward side of the evaporator in the refrigerant introduction pipe for introducing the refrigerant into the evaporator;
Heating means for heating the air on the windward side of the evaporator,
In the case of performing the normal defrosting process, the control unit stops the supply of the refrigerant to the evaporator and drives the heating unit, and the air temperature detected by the air temperature sensor is determined in advance. The heating means is stopped when the temperature becomes equal to or higher than the first reference temperature, and the temperature of the refrigerant detected by the refrigerant temperature sensor becomes equal to or higher than a predetermined second reference temperature lower than the first reference temperature. while starting the supply of the refrigerant to come to have, when performing the simple defrosting process, the cause of the supply of refrigerant to the evaporator with stops driving the heating means, it has elapsed a predetermined time A cooling device characterized in that the supply of the refrigerant is sometimes started and the heating means is stopped. The control means includes
A temperature difference calculating means for calculating a difference between an air temperature blown into the storage chamber and a temperature detected by the air temperature sensor;
Update storage means for calculating an average value of differences calculated by the temperature difference calculation means in a stable period from defrosting completion to frost formation for each defrosting process, and updating / storing it as a stable value;
Deviation calculation means for calculating a deviation of the current temperature difference with respect to the stable value stored by the update storage means;
Change amount calculating means for calculating a temporal change amount of the deviation calculated by the deviation calculating means;
An inference unit that estimates the frost formation amount by fuzzy inference based on the temperature difference deviation calculated by the deviation calculation unit and the temporal change amount calculated by the change amount calculation unit, and obtains the defrosting start timing;
With
The cooling device according to claim 1 or 2, wherein a defrosting process start command is given according to the defrosting start timing .

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