JP4784588B2 - Cooling system - Google Patents

Description

  The present invention relates to a cooling device.

  FIG. 17 is a side view showing a general showcase in a partial cross section. As shown in FIG. 17, the showcase is an open showcase 100 having no glass door on the front surface, and a main body cabinet 100a formed as a substantially rectangular heat-insulating housing having an open front surface and a product display shelf 500 are arranged. A storage chamber 400 provided, an inner duct 200 and an outer duct 300, and an 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 high-pressure refrigerant supplied from the condenser to a low-pressure state by a throttling effect and a function of adjusting the 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 a pipe.

  The air cooled by the evaporator 130 is blown out through the inner duct 200 from the outlet 200b toward the lower side of the housing chamber 400 by operating a blower fan 160 provided in the inner duct 200 to form an air curtain. Then, the air is 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, supply of the refrigerant is stopped, and then the heater 150 installed on the windward side below the evaporator 130, that is, the blower fan 160 side is energized to melt the frost, and passes above the evaporator 130, that is, passes. When the air temperature sensor S installed in the vicinity of the leeward side of the air detects that the air temperature has become equal to or 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. Restart cooling operation.

  Since this periodic defrosting usually takes about 30 minutes, when this defrosting is frequently performed, the temperature inside the open showcase 100 rises and the freshness of the product falls. Therefore, defrosting with a short time (hereinafter referred to as “simple defrosting”) is performed between the operation of the above periodic defrosting (hereinafter referred to as “normal defrosting”) 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. Accordingly, although the internal temperature temporarily rises slightly by performing simple defrosting, the temperature does not increase as much as normal defrosting because of the short time, and the freshness of the product in the storage chamber 400 is affected. 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-mentioned open showcase 100, since defrosting was normally performed only based on the air temperature sensor S which detects the temperature of the air after passing the evaporator 130, there existed 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. Similarly, frost attached to the upper portions on 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.

  In order to melt such unmelted frost, the reference temperature for determining the end of energization of the heater 150 can be set higher, but this may cause an increase in internal temperature. .

  An object of this invention is to provide the cooling device which can defrost reliably, suppressing the temperature rise of cooling object in view of the said situation.

  In order to achieve the above object, a cooling device according to claim 1 of the present invention includes an air temperature sensor for detecting the temperature of air after passing through the evaporator, and heating the air before passing through the evaporator. Heating means and control means for performing defrosting processing of the evaporator, wherein the control means sets a predetermined first reference temperature and a predetermined draining time in the defrosting processing. A first step of driving the heating means until the temperature detected by the air temperature sensor is equal to or higher than the first reference temperature, and from the time when the heating means is stopped until the draining time elapses. A cooling device that continuously performs the second step of stopping the supply of the refrigerant to the evaporator, comprising a refrigerant temperature sensor that detects the temperature of the refrigerant at the inlet of the evaporator, and the control means includes , Excluding During the processing, the time from when the temperature detected by the refrigerant temperature sensor becomes equal to or higher than a predetermined second reference temperature until the draining time elapses is measured as a stable time, and the stable The set condition is updated according to a comparison result between the time and a predetermined reference time.

  According to a second aspect of the present invention, in the cooling device according to the first aspect, the control unit updates the first reference temperature according to whether or not the stable time is in the reference time range. It is characterized by that.

  The cooling device according to a third aspect of the present invention is the cooling device according to the first aspect, wherein the control means updates the draining time according to whether the stable time is in the reference time range. And

  According to a fourth aspect of the present invention, there is provided the cooling device according to the first aspect, wherein the control means detects the temperature of the air blown into the cooling chamber after passing through the evaporator and the air temperature sensor. The defrosting unit calculates a temperature difference calculating means for calculating a difference from the measured temperature, a temperature of the air blown into the cooling chamber after passing through the evaporator, and a temperature of the air after passing through the evaporator. An update storage means for detecting each time during a stable period from completion to frost formation, and storing an average value of values calculated by the temperature difference calculation means based on the detected temperature as a stable value; and the evaporator The temperature of the air blown into the cooling chamber after passing through and the temperature of the air after passing through the evaporator are detected after the stabilization period has passed, and the detected temperature and the stability stored in the update storage means are stored. Deviation calculation to calculate the deviation from the value A change amount calculating means for calculating a temporal change amount of the deviation calculated by the deviation calculating means, a deviation of the temperature difference calculated by the deviation calculating means, and a temporal change amount calculated by the change amount calculating means. An inferring unit that estimates the amount of frost formation by fuzzy inference and determines whether the defrosting process is necessary or whether the draining time is necessary, and performs the defrosting process according to a result obtained by the inference unit. Features.

  According to the cooling device of the present invention, during the defrosting process, the time from when the temperature detected by the refrigerant temperature sensor becomes equal to or higher than the predetermined second reference temperature until the draining time elapses. Is measured as a stable time, and the setting condition is updated according to the comparison result between the stable time and a predetermined reference time. For this reason, by updating the setting condition so that the stabilization time approaches the reference time, the time during which the temperature in the vicinity of the refrigerant temperature sensor rises can be shortened, and thus the temperature rise of the cooling target can be suppressed. Moreover, since the frost near the refrigerant temperature sensor can be removed by setting the second reference temperature to a temperature at which frost can be removed, the evaporator can be reliably defrosted.

  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 (cooling 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 with respect to the storage chamber 4 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 condenses (heatsinks) 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 low-temperature and low-pressure refrigerant (liquid refrigerant). It is something to be made.

  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 according to the first embodiment is a finned coil evaporator composed of, for example, a copper pipe 13a and an aluminum fin 13b, and an upper side portion is a refrigerant inlet (inlet portion) 13c. The lower side is a 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. 1) 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 toward the evaporator 13 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 introduction pipe 14. Thus, the refrigerant enters the copper pipe 13a from the refrigerant inlet 13c 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 evaporates (heat absorption) to become a low-temperature and low-pressure gas refrigerant. Cool down. 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, the blower fan 16 is driven to enter the inner duct 2 from the suction port 2a, and the internal air (the internal air of the housing chamber 4) is cooled when passing around the evaporator 13, and then the inner duct 2 is cooled. The 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. When the outer fan is driven, the air passing through the outer duct 3 is directed downward from the air outlet 3 b. By blowing out, 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 normal defrost control unit 22, a simple defrost control unit 23, and a setting condition update 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, the process time of the simple defrost process mentioned later, and the reference time in the setting condition update process mentioned later are preset and memorize | stored. In the first embodiment, for example, the second reference temperature is set to 0 ° C., the draining time is set to 8 minutes, the processing time is set to 5 minutes, and the reference time is set to a range of 8 to 18 minutes. 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 first reference temperature is, for example, 7 ° C. by default.

  The normal defrost control unit 22 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 23 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a simple defrost process. The setting condition update unit 24 is for updating the information stored in the setting storage unit 21 when performing the setting condition update process. The update target in the first embodiment is the first reference temperature.

  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. The normal defrosting process may be performed periodically based on a set time stored in advance in the setting storage unit 21. For example, when a switch or the like is manually operated, a defrost control means 20 may perform the normal defrosting process.

  First, in the normal defrosting process shown in FIG. 4, the defrost control means 20 acquires the 1st reference temperature memorize | stored in the setting memory | storage part 21 through the normal defrost control part 22 (step S101). Next, the expansion valve 12 is closed through the normal defrost control unit 22 (step S102), and the heater 15 is energized and driven through the normal defrost control unit 22 (step S103). By closing the expansion valve 12 in this way, the supply of the refrigerant to the evaporator 13 is stopped. In addition, the air heated by the heater 15 in step S <b> 103 passes through 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 defrosting control means 20 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 S104).

  And the defrost control means 20 judges whether outlet air temperature is more than 1st reference temperature acquired by step S101 through the normal defrost control part 22 (step S105), and exit air temperature is 1st reference | standard. When the temperature is lower than the temperature (step S105: No), the process of step S104 is performed. On the other hand, when the outlet air temperature is equal to or higher than the first reference temperature (step S105: Yes), the normal defrost control unit. 22, the energization of the heater 15 is stopped, that is, the heater 15 is stopped (step S106).

  Simultaneously with step S106, time measurement is started through the normal defrost control unit 22 (step S107). Here, by stopping the driving of the heater 15 in step S106, the removal of water generated from the melting of frost, so-called draining, is started.

  Then, it is determined whether or not the measurement time started in step S107 has passed a 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 22 (step S109), the current process is terminated, and the procedure is returned. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  In the cooling device according to the first 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. That is, 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 hindered by frost. It means not.

  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. The simple defrosting process may be performed periodically between the normal defrosting process and the next normal defrosting process based on the set time stored in the setting storage unit 21 in advance. When a switch or the like is artificially operated, the defrost control means 20 may perform a simple defrost process.

  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 23 (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 23 (step S202), and simultaneously starts time measurement through the simple defrost control unit 23 (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 defrosting control unit 23, that is, the drive of the heater 15 is stopped, the expansion valve 12 is opened (step S205), the current process is terminated, and the procedure To return. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  In the cooling device according to the first embodiment of the present invention as described above, the number of times of the normal defrosting process can be reduced by performing the simple defrosting process, so that the operation cycle of the normal defrosting process is lengthened. It becomes possible to make it.

  FIG. 6 is a flowchart showing the contents of the setting condition update process performed by the defrost control means shown in FIG. Hereinafter, the operation of the cooling device will be further described with reference to FIG.

  First, in the setting condition update process shown in FIG. 6, the defrost control means 20 determines whether the normal defrost control part 22 started the normal defrost process through the setting condition update part 24 (step S301).

  When the normal defrosting process is started (step S301: Yes), the defrosting control unit 20 detects the temperature of the refrigerant (inlet refrigerant temperature) supplied to the evaporator 13 through the inlet refrigerant temperature sensor S2 (step S301). S302). Thereafter, the defrosting control means 20 determines whether or not the inlet refrigerant temperature is equal to or higher than the second reference temperature stored in the setting storage unit 21 through the setting condition update unit 24 (step S303), and the inlet refrigerant temperature is the first. When the temperature is less than 2 reference temperatures (step S303: No), the processing of step S302 is executed, whereas when the inlet refrigerant temperature is the second reference temperature (step S303: Yes), the setting condition update unit The time measurement is started through 24 (step S304).

  Next, the defrost control means 20 judges whether the normal defrost control part 22 complete | finished the normal defrost process through the setting condition update part 24 (step S305).

  When the normal defrosting process is finished (step S305: Yes), the measurement time started in step S305 is finished.

  And the defrost control means 20 judges whether the time (stable time) measured from step S304 to step S305 through the setting condition update part 24 is in the reference time range memorize | stored in the setting memory | storage part 21 (step). S306) If the stable time is within the reference time range (step S306: Yes), the current process is terminated and the procedure is returned. Here, the reference time is a target of the stabilization time, and is set to such an extent that the goods stored in the storage chamber 4 are not adversely affected if the stabilization time is within the reference time range. That is, even if the state where the inlet refrigerant temperature is equal to or higher than the second reference temperature continues, the commodity stored in the storage chamber 4 is not adversely affected if the duration is within the reference time range.

  On the other hand, when the stable time is not in the reference time range (step S306: No), it is determined whether or not the stable time is smaller than the minimum value of the reference time (step S307), and the stable time is the minimum of the reference time. In the case of a value smaller than the value (step S307: Yes), a value obtained by adding a predetermined value (for example, 0.5 ° C., α in FIG. 6) to the first reference temperature stored in the setting storage unit 21, The first reference temperature in the setting storage unit 21 is updated (step S308). On the other hand, if the stable time is not smaller than the minimum value of the reference time (step S307: No), the first reference temperature stored in the setting storage unit 21 is updated. The first reference temperature in the setting storage unit 21 is updated to a value obtained by subtracting a predetermined value (for example, 0.5 ° C., α in FIG. 6) from the one reference temperature (step S309). This ends the current process and returns the procedure. The value for updating the first reference temperature in step S307 may be a value stored in advance in the setting storage unit 21 with respect to the first reference temperature. For example, the difference between the reference time and the stable time is large. In this case, a large value may be added to or subtracted from the first reference temperature. On the other hand, if the difference between the reference time and the stabilization time is small, a small value may be added to or subtracted from the first reference temperature. However, it is desirable to set an upper limit and a lower limit for the first reference temperature in advance, and update the first reference temperature within the upper and lower limits.

  7, 8, and 9 are graphs showing examples of temperatures detected by the refrigerant temperature sensor when the defrost control unit shown in FIG. 3 performs the normal defrosting process. Here, FIG. 7 shows an example in which the stable time t (see FIG. 7) is in the reference time range.

  On the other hand, FIG. 8 shows an example in which the stabilization time t (see FIG. 8) is 0, that is, the stabilization time is smaller than the minimum value of the reference time. That is, the inlet refrigerant temperature has not reached the second reference temperature, and it can be determined that frost has not melted in the vicinity of the inlet refrigerant temperature sensor S2. In this case, when the defrost control means 20 performs the setting condition update process, the first reference temperature in the setting storage unit 21 is updated to a value obtained by adding a predetermined value to the first reference temperature. Therefore, when the defrost control means 20 performs the next normal defrost process, the heater 15 is driven until the temperature detected by the outlet air temperature sensor S1 reaches the updated first reference temperature. Therefore, melting of frost is promoted more than the previous normal defrosting process. Thus, if the defrost control means 20 repeats the normal defrost process and the setting update process, the inlet refrigerant temperature will eventually reach the second reference temperature, and it is determined that the frost near the inlet refrigerant temperature sensor S2 has been melted. it can. Here, the fact that the inlet refrigerant temperature reaches the second reference temperature means that the frost has melted even at the position where the frost is most likely to remain unmelted. That is, the frost adhering to the evaporator 13 can be completely melted.

  FIG. 9 shows an example when the stable time t (see FIG. 9) is larger than the maximum value of the reference time. As is clear from FIG. 9, in this example, the maximum temperature is significantly higher than that in FIG. That is, the temperature in the storage chamber 4 rises, and there is a risk of adversely affecting the products stored in the storage chamber 4. In this case, when the defrost control means 20 performs the setting condition update process, the first reference temperature in the setting storage unit 21 is updated to a value obtained by subtracting a predetermined value from the first reference temperature. Therefore, when the defrost control means 20 performs the next normal defrost process, the heater 15 is driven until the temperature detected by the outlet air temperature sensor S1 reaches the updated first reference temperature. Therefore, heating of air is suppressed more than the previous normal defrosting process. Thus, if the defrost control means 20 repeats a normal defrost process and a setting update process, the time when the maximum temperature of inlet refrigerant temperature will fall and it exceeds 2nd reference temperature will decrease soon.

  According to the cooling device in Embodiment 1 of the present invention as described above, the temperature detected by the inlet refrigerant temperature sensor S2 is equal to or higher than the predetermined second reference temperature during the normal defrosting process. The time from when the water draining time elapses is measured as the stable time, and the set condition is updated according to the comparison result between the stable time and a predetermined reference time. For this reason, by updating the setting condition so that the stabilization time approaches the reference time, the time during which the temperature in the vicinity of the inlet refrigerant temperature sensor S2 is rising can be shortened, so that the temperature increase in the storage chamber 4 to be cooled can be reduced. Can be suppressed. Moreover, since the frost near the inlet refrigerant temperature sensor S2 can be removed by setting the second reference temperature to a temperature at which frost can be removed, the evaporator 13 can be reliably defrosted.

  In addition, according to the cooling device in Embodiment 1 of the present invention as described above, when the ambient temperature changes with the movement of the installation position of the open showcase 1, the position and number of products stored in the storage chamber 4 are the same. Even in the case of a change, the setting condition is updated so as to bring the stabilization time closer to the reference time, so that the temperature rise of the storage chamber 4 can be suppressed and the evaporator 13 is surely defrosted. Can do.

<Embodiment 2>
FIG. 10 is a block diagram showing a control system of the cooling device according to Embodiment 2 of the present invention. The cooling device in the second embodiment is different from the first embodiment described above in the contents of the normal defrosting process and the setting condition update process performed by the defrosting control means. Hereinafter, this difference will be described in detail. 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. 10, 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 normal defrost control unit 32, a simple defrost control unit 33, and a setting condition update 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 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, the process time of the simple defrost process mentioned later, and the reference time in the setting condition update process mentioned later are preset and memorize | stored. In the second embodiment, for example, the first reference temperature is 7 ° C., the second reference temperature is 0 ° C., the processing time is 5 minutes, and the reference time is in the range of 8 to 18 minutes. 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 draining time is, for example, 8 minutes by default.

  The normal defrost control part 32 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a normal defrost process. The simple defrost control part 33 is for controlling the drive of the expansion valve 12 and the heater 15 when performing a simple defrost process. The setting condition update unit 34 is for updating the information stored in the setting storage unit 31 when performing the setting condition update process. The update target in the second embodiment is the draining time.

  FIG. 11 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. 11, the defrost control means 30 acquires the draining time stored in the setting storage unit 31 through the normal defrost control unit 32 (step S401). Next, the expansion valve 12 is closed through the normal defrost control unit 32 (step S402), and the heater 15 is energized and driven through the normal defrost control unit 32 (step S403). 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 S403 passes through 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 (exit air temperature) on the leeward side of the evaporator 13 through the exit air temperature sensor S1 (step S404).

  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 32 (step S405), and the outlet air temperature is determined. When the temperature is lower than the first reference temperature (step S405: No), the process of step S404 is performed. On the other hand, when the outlet air temperature is equal to or higher than the first reference temperature (step S405: Yes), the normal removal is performed. The energization of the heater 15 is stopped through the frost control unit 32, that is, the heater 15 is stopped (step S406).

  Simultaneously with step S406, time measurement is started through the normal defrost control unit 32 (step S407). Here, by stopping the driving of the heater 15 in step S406, the removal of water resulting from the melting of frost, so-called draining, is started.

  Then, it is determined whether or not the measurement time started in step S407 has passed the predetermined time, that is, the draining time acquired in step S401 (step S408), and when the draining time has elapsed (step S408: Yes). In this case, the expansion valve 12 is opened through the normal defrost control unit 32 (step S409), the current process is terminated, and the procedure is returned. Thereby, the supply of the refrigerant to the evaporator 13 is started.

  In the cooling device according to Embodiment 2 of the present invention as described above, the driving of the heater 15 is stopped when the outlet air temperature is equal to or higher than the first reference temperature in the normal defrosting process. That is, 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 hindered by frost. It means not.

  FIG. 12 is a flowchart showing the contents of the setting condition update 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 setting condition update process shown in FIG. 12, the defrost control means 30 determines whether the normal defrost control part 32 has started the normal defrost process through the setting condition update part 34 (step S501).

  When the normal defrosting process is started (step S501: Yes), the defrosting control unit 30 detects the temperature of the refrigerant (inlet refrigerant temperature) supplied to the evaporator 13 through the inlet refrigerant temperature sensor S2 (step S501). S502). Thereafter, the defrosting control means 30 determines whether or not the inlet refrigerant temperature is equal to or higher than the second reference temperature stored in the setting storage unit 31 through the setting condition update unit 34 (step S503), and the inlet refrigerant temperature is the first. When the temperature is less than 2 reference temperatures (step S503: No), the process of step S502 is executed. On the other hand, when the inlet refrigerant temperature is the second reference temperature (step S503: Yes), the setting condition update unit Time measurement is started through 34 (step S504).

  Next, the defrost control means 30 judges whether the normal defrost control part 32 complete | finished the normal defrost process through the setting condition update part 34 (step S505).

  When the normal defrosting process is finished (step S505: Yes), the measurement time started in step S505 is finished.

  And the defrost control means 30 judges whether the time (stable time) measured from step S504 to step S505 through the setting condition update part 34 is in the reference time range memorize | stored in the setting memory | storage part 31 (step). S506) When the stable time is within the reference time range (step S506: Yes), the current process is terminated and the procedure is returned. Here, the reference time is a target of the stabilization time, and is set to such an extent that the goods stored in the storage chamber 4 are not adversely affected if the stabilization time is within the reference time range. That is, even if the state where the inlet refrigerant temperature is equal to or higher than the second reference temperature continues, the commodity stored in the storage chamber 4 is not adversely affected if the duration is within the reference time range.

  On the other hand, when the stable time is not in the reference time range (step S506: No), it is determined whether or not the stable time is smaller than the minimum value of the reference time (step S507), and the stable time is the minimum of the reference time. When the value is smaller than the value (step S507: Yes), the setting storage unit 31 is added to a value obtained by adding a predetermined value (for example, 1 minute, α in FIG. 12) to the draining time stored in the setting storage unit 31. On the other hand, if the stable time is not smaller than the minimum value of the reference time (step S507: No), a predetermined value (for example, from the draining time stored in the setting storage unit 31) is updated (step S508). The draining time in the setting storage unit 31 is updated to a value obtained by subtracting 1 minute (step S509). This ends the current process and returns the procedure. It should be noted that the value for updating the draining temperature in step S507, and the value for updating the draining time in step S507, can be obtained by adding or subtracting a value stored in advance in the setting storage unit 31 with respect to the draining time. When the difference between the time and the stable time is large, the large value is adjusted to the draining time. On the other hand, when the difference between the reference time and the stable time is small, the small value is adjusted to the draining time. It doesn't matter. However, it is desirable to set an upper limit and a lower limit in advance for the draining time, and update the draining time within the upper and lower limits.

  Thus, according to the cooling device in Embodiment 2 of the present invention, the target for which the defrost control means 30 performs the setting condition update process is the draining time. Here, during the draining time, the driving of the heater 15 is stopped, but warm air can be blown toward the evaporator 13 by driving the blower fan 16. Therefore, when the defrost control means 30 performs the setting condition update process and the drainage time of the setting storage unit 31 is updated to a value obtained by adding a predetermined value to the drainage time, the defrost control means 30 performs the next normal operation. When performing a defrost process, melting | fusing of frost is accelerated | stimulated rather than the last normal defrost process. On the other hand, when the defrosting control means 30 performs the setting condition update process and the draining time of the setting storage unit 31 is updated to a value obtained by subtracting a predetermined value from the draining time, it is earlier than the previous normal defrosting process. In step, the supply of the refrigerant to the evaporator 13 is started. Therefore, the temperature rise of the storage chamber 4 can be suppressed. Therefore, also in the cooling device of the second embodiment configured as described above, the same operational effects as those of the first embodiment can be obtained.

<Embodiment 3>
FIG. 13 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. 13, the cooling device includes a defrost control means 20 'as one of its control systems. The defrost control unit 20 ′ includes a setting storage unit 21, a normal defrost control unit 22, a simple defrost control unit 23, a setting condition update unit 24, and a defrost start determination unit 40.

  The defrosting start determination means 40 performs the normal defrosting process and the simple defrosting process so that the number of times of the normal defrosting process and the simple defrosting process to be performed is the minimum necessary number for defrosting. As shown in FIG. 14, the air temperature difference calculation unit 41, the deviation calculation unit 42, the change amount calculation unit 43, the post-defrost elapsed time measurement unit 44, and the time difference calculation unit 45 are obtained. , A defrosting interval calculation unit 46, a fuzzy inference unit 47, a membership function 48, and a rule unit 49 are provided.

  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 air blown out from the blowout port 2b.

  The deviation calculating unit 42 calculates a difference ΔT between the temperature difference (T1-T2) calculated through the air temperature difference calculating unit 41 and the stable value T0 of the open showcase 1. Here, the stable value T0 is a unique value obtained during the normal defrosting process of the open showcase 1, and is stored in the setting storage unit 21 in the third embodiment. That is, when the normal defrosting process is started, the blown air temperature and the outlet air temperature rise once and then drop and stabilize. Usually, it takes about 2 hours to stabilize, and then it is kept constant for about 1 hour until frosting starts (stable period). A temperature difference (T1-T2) is calculated based on the blown air temperature T1 and the outlet air temperature T2 detected during this time, and the calculated value is taken in every stable period, 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 an elapsed time tp from the previous normal defrosting process.

  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 arranged 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 reasoning unit 47 obtains the necessity of the normal defrosting process and the necessity of the simple defrosting process by fuzzy reasoning 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 or absence of defrosting based on each input data, a membership function 48 described later, and a rule set in a rule unit 49 described later. .

  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 variation dT, the time difference Δt, and the consequent part of the rule part 49 described later, or It is used to determine the margin or irrationality such as how much margin is available before defrosting and whether or not defrosting is necessary.

  The rule unit 49 defines rules for determining the presence or absence of defrosting in the fuzzy reasoning unit 47. Specifically, the know-how regarding the defrost control possessed by a specialist engineer for the open showcase 1 as shown in FIG. 15 is made into a rule. When the deviation ΔT increases, the defrosting starts and the deviation ΔT decreases. If the time difference Δt becomes larger, the simple defrosting process starts, if the temporal change dT becomes larger, the simple defrosting process starts and so on. In FIG. 15, the consequent part describes whether or not simple defrosting is necessary except for normal defrosting.

  FIG. 16 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 air temperature sensor S3 and detects the outlet air temperature T2 through the outlet air temperature sensor S1 ( Step S601).

  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 S602), and then air through the deviation calculating unit 42. A deviation ΔT between the temperature difference (T1−T2) calculated by the temperature difference calculation unit 41 and the stable value T0 of the open showcase 1 is calculated (step S603).

  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 S604). The defrosting start determination means 40 that has calculated the temporal change amount dT measures the elapsed time tp from the previous normal defrosting process through the post-defrosting elapsed time measurement unit 44 (step S605), and the time difference calculation 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 S606).

  Then, the defrosting start judging means 40 estimates the defrosting by the fuzzy inference based on the input deviation ΔT, temporal change dT, and time difference Δt through the fuzzy inference unit 47, and whether or not the normal defrosting process is necessary. And the necessity of simple defrost processing is determined (step S607), this process is complete | finished, and a procedure is returned.

  In the cooling device according to Embodiment 3 of the present invention as described above, the defrost control means 20 ′ performs the defrost start determination process when the blown air temperature T1 and the outlet air temperature T2 are detected. Yes. Here, the blown air temperature T1 and the outlet air temperature T2 are substantially the same during the stable period. On the other hand, after the stable period has passed, the blown air temperature T1 and the outlet air temperature T2 gradually cause frost to adhere to the evaporator 13, and the blown air temperature T1 rises. Therefore, if the blown air temperature T1 and the outlet air temperature T2 after the stable period has elapsed are detected, the defrosting is estimated by fuzzy inference based on the deviation ΔT, the time variation dT, and the time difference Δt, and the normal defrosting is performed. The necessity of a process and the necessity of a simple defrost process can be calculated | required.

  Thus, according to the cooling device in Embodiment 3 of this invention, defrost control means 20 'implements a defrost start judgment process, and therefore the necessity of a normal defrost process and the necessity of a simple defrost process Can be requested. Therefore, the defrost control means 20 ′ defrosts through the normal defrost control part 22 or the simple defrost control part 23 according to the result obtained by the inference part 47 in the defrost start determination means 40, thereby fuzzy inference. The defrosting can be appropriately performed according to the amount of frost formation estimated by the above. Furthermore, if a predetermined cycle is stored in the setting storage unit 21 and the defrosting start determination process is performed in that cycle, the amount of frost formation on the evaporator 13 is estimated, and the defrosting control means 20 is determined at the timing determined to be necessary. 'Will perform normal defrosting treatment or simple defrosting treatment. Therefore, the number of times of performing the normal defrosting process and the simple defrosting process to be performed can be set to the minimum number necessary for defrosting. 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.

  The present invention is useful for a cooling device, and is particularly suitable for a cooling device considering defrosting properties.

It is the side view which showed the open showcase to which the cooling device in Embodiment 1 of this invention was applied in the partial cross section. It is a perspective view which shows the evaporator shown in FIG. It is a block diagram which shows the control system of the cooling device in Embodiment 1 of this invention. It is a flowchart which shows the content of the normal defrost process which the defrost control means shown in FIG. 3 implements. It is a flowchart which shows the content of the simple defrost process which the defrost control means shown in FIG. 3 implements. It is a flowchart which shows the content of the setting condition update process which the defrost control means shown in FIG. 3 implements. It is a graph which shows an example of the temperature which a refrigerant | coolant temperature sensor detects when the defrost control means shown in FIG. 3 implements a normal defrost process. It is a graph which shows an example of the temperature which a refrigerant | coolant temperature sensor detects when the defrost control means shown in FIG. 3 implements a normal defrost process. It is a graph which shows an example of the temperature which a refrigerant | coolant temperature sensor detects when the defrost control means shown in FIG. 3 implements a normal defrost process. It is a block diagram which shows the control system of the cooling device in Embodiment 2 of this invention. It is a flowchart which shows the content of the normal defrost process which the defrost control means shown in FIG. 10 implements. It is a flowchart which shows the content of the setting condition update process which the defrost control means shown in FIG. 10 implements. It is a block diagram which shows the control system of the cooling device in Embodiment 3 of this invention. It is a block diagram which shows the defrost start judgment means shown in FIG. It is a graph which shows an example of the rule defined in the rule part. It is a flowchart which shows the content of the defrost start judgment process which the defrost control means shown in FIG. 13 implements. It is the side view which showed the general showcase in the partial cross section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Open showcase 4 Accommodating room 11 Refrigerator 12 Expansion valve 13 Evaporator 13a Copper pipe 13b Aluminum fin 13c Refrigerant inlet 13d Refrigerant outlet 15 Heater 16 Blower fan 20, 30 Defrost control means 20 'Defrost control means 21, 31 setting Storage unit 22, 32 Normal defrost control unit 23, 33 Simple defrost control unit 24, 34 Setting condition update unit 40 Defrost start determination means 41 Air temperature difference calculation unit 42 Deviation calculation unit 43 Change amount calculation unit 44 After defrosting Elapsed time measurement section 45 Time difference calculation section 46 Defrost interval calculation section 47 Fuzzy inference section 48 Membership function 49 Rule section S1 Outlet air temperature sensor S2 Inlet refrigerant temperature sensor

Claims (4)

An air temperature sensor for detecting the temperature of the air after passing through the evaporator;
Heating means for heating the air before passing through the evaporator;
Control means for performing a defrosting process of the evaporator,
In the defrosting process, the control unit acquires a predetermined first reference temperature and a predetermined draining time as setting conditions, and a temperature detected by the air temperature sensor is equal to or higher than the first reference temperature. The first step of driving the heating means until the time is reached and the second step of continuously stopping the supply of the refrigerant to the evaporator from the time when the heating means is stopped until the draining time elapses. A cooling device,
A refrigerant temperature sensor for detecting the temperature of the refrigerant at the inlet of the evaporator;
While the defrosting process is being performed, the control means determines a time from when the temperature detected by the refrigerant temperature sensor becomes equal to or higher than a predetermined second reference temperature until the draining time elapses. A cooling device that measures as a stabilization time and updates the set condition in accordance with a comparison result between the stabilization time and a predetermined reference time.   2. The cooling device according to claim 1, wherein the control unit updates the first reference temperature according to whether or not the stable time is in the reference time range.   The cooling device according to claim 1, wherein the control unit updates the draining time according to whether or not the stable time is in the reference time range. The control means includes
A temperature difference calculating means for calculating a difference between the temperature of the air blown into the cooling chamber after passing through the evaporator and the temperature detected by the air temperature sensor;
The temperature of the air blown into the cooling chamber after passing through the evaporator and the temperature of the air after passing through the evaporator are detected at every stable period from the completion of the defrosting until the frost is formed. Update storage means for storing an average value of values calculated by the temperature difference calculation means based on the detected temperature as a stable value;
The temperature of the air blown into the cooling chamber after passing through the evaporator and the temperature of the air after passing through the evaporator are detected after the stable period has elapsed, and the detected temperature and the update storage means Deviation calculating means for calculating a deviation from the stored stable value;
A change amount calculating means for calculating a temporal change amount of the deviation calculated by the deviation calculating means;
The frost formation amount is estimated by fuzzy inference based on the temperature difference deviation calculated by the deviation calculation means and the temporal change amount calculated by the change amount calculation means, and whether or not the defrosting process is necessary or whether or not the draining time is necessary An inference part for
The cooling device according to claim 1, wherein the defrosting process is performed based on a result obtained by the inference unit.