JP2014178039A - Cooling box - Google Patents

Abstract

An object of the present invention is to more efficiently control the temperature in a heat insulating housing of a cold storage and reduce power consumption.
A storage for storing an object to be cooled, a cooling device for cooling the inside of the storage by evaporating a refrigerant with an evaporator, an internal temperature sensor for detecting the temperature inside the storage, and evaporation A first heater that melts frost adhering to the container, a drain pan that receives water or frost dripping from the evaporator, a second heater that heats the drain pan, and the temperature detected by the internal temperature sensor is the upper limit allowable temperature in the storage And a control device that operates the first heater and the second heater during a period when the cooling device is intermittently operated so as to be between the lower limit allowable temperature and the operation of the cooling device is stopped. The control device controls the operation of the second heater not to be performed during the period in which the operation of the cooling device is stopped when the ratio of the operation period of the cooling device in the predetermined period is less than the predetermined value. Refrigerator according to claim.
[Selection] Figure 1

Description

  The present invention relates to a cold storage.

  A cool box for cooling and storing a cooling target such as blood, a drug, or a cell at a predetermined temperature has been developed. Such a cool box is configured to include a heat insulating casing and a refrigeration apparatus, and the refrigeration apparatus is operated intermittently to control the internal temperature within a certain temperature range.

  However, since the internal temperature is likely to fluctuate due to the influence of changes in the outside air temperature, opening / closing of the door, etc., various techniques for managing the internal temperature with higher accuracy have been developed (for example, patents). Reference 1).

JP-A-8-31534

  Such a cool box cools the inside of the warehouse through an evaporator arranged in a heat insulating casing, but frost tends to adhere to the surface of the evaporator.

  When this frost is melted, it becomes water droplets and drops from the evaporator. Therefore, the cold storage is provided with a drain pan as a tray for the water droplets. And the cold storage is made to discharge | emit the water stored by this drain pan through the pipe connected to the exterior.

  However, the water dripped onto the drain pan adheres to the evaporator as frost and may freeze again because of low temperature. If freezing occurs, water may not be discharged. Therefore, a heater for heating the drain pan is provided, and the heater is operated during the operation stop period of the refrigeration apparatus.

  However, operating the heater during the operation period of the refrigeration system increases the temperature rise rate compared to the case where the heater is not operated, and thus increases the operation frequency of the refrigeration apparatus that operates intermittently. Increases and causes a failure rate of the refrigeration apparatus to increase.

  In addition, since either one of the refrigeration apparatus and the heater repeats the operation without interruption, the energy efficiency is poor in that power is always supplied to, for example, a compressor or an electric heater.

  The invention for solving the above problems includes a storage for storing an object to be cooled, a cooling device for cooling the interior of the storage by evaporating a refrigerant with an evaporator, and a temperature inside the storage. An internal temperature sensor, a first heater that melts frost attached to the evaporator, a drain pan that receives water or frost dripping from the evaporator, and freezing suppression or frost melting of water droplets stored in the drain pan. Therefore, the temperature detected by the second heater that heats the drain pan and the internal temperature sensor is between the first temperature that is the upper limit allowable temperature and the second temperature that is the lower limit allowable temperature in the storage. And a control device that operates the first heater and the second heater during a period when the cooling device is intermittently operated and the operation of the cooling device is stopped. When the ratio of the operation period of the cooling device that operates intermittently becomes less than a predetermined value, the second heater is not operated during the period when the operation of the cooling device is stopped. It is characterized by controlling.

  ADVANTAGE OF THE INVENTION According to this invention, the temperature in the heat insulation housing | casing of a cool box can be controlled more efficiently, and power consumption can also be reduced.

It is a fragmentary sectional view which shows an example of the whole structure of the cool box of this Embodiment. It is a block diagram which shows an example of the structure which manages control of the cool box of this Embodiment. It is a flowchart which shows an example of the process sequence of CPU of this Embodiment. It is a diagram which shows an example of the time change of the temperature in the heat insulation housing | casing of this Embodiment, the temperature of an evaporator, the operation state of a compressor, and the operation state of a defrost heater and a drain pan heater.

=== Example structure of cold storage ===
A configuration example of the cool box 1 according to the present embodiment will be described with reference to FIGS. 1 and 2. 1 is a partial cross-sectional view showing an example of the overall configuration of the cool box 1, and FIG. 2 is a block diagram showing an example of the configuration that controls the cool box 1.

  As illustrated in FIGS. 1 and 2, the cool box 1 includes a refrigeration device (cooling device) 2, a defrost heater (first heater) 12, a drain pan heater (second heater) 19, and a drain pan (a saucer). ) 33, a heat insulating housing 3, a heat insulating door 4, and a control board (control device) 10.

  As illustrated in FIG. 1, the refrigeration apparatus 2 is configured by connecting a compressor 11, a condenser 21, a capillary tube (decompressor) 22, and an evaporator 23 in a ring shape with a refrigerant pipe. In the refrigeration apparatus 2, the refrigerant discharged from the compressor 11 is condensed by the condenser 21 in order to obtain the refrigerant action, and then evaporated by the evaporator 23 through the pressure reduction in the capillary tube 22. In particular, the evaporator 23 of the present embodiment is composed of, for example, a meandering evaporation tube, and is disposed on the back side (the right side in FIG. 1) in the heat insulating casing 3. In the illustration of FIG. 1, an evaporator temperature sensor 14 such as a thermistor for detecting the temperature of the evaporator 23 is attached to the surface of the refrigerant pipe connected to the refrigerant inlet side of the evaporation tube constituting the evaporator 23. It has been.

  As illustrated in FIG. 1, the defrosting heater 12 is used to suppress the attachment of frost to the surface of the evaporation tube constituting the evaporator 23 or to melt the frost attached to the surface. For example, a heating device such as an electric heater. As will be described later, the defrost heater 12 of the present embodiment is energized during a period in which the refrigeration apparatus 2 is not operating so as to operate alternately with the refrigeration apparatus 2.

  As illustrated in FIG. 1, the heat-insulating housing 3 has a front side (left side in FIG. 1) for taking in and out articles to be cooled (objects to be cooled, such as blood, vaccines, medicines, etc.). An evaporator 23 with a defrost heater 12 is arranged through a partition plate 31 on the back side (the right side in FIG. 1) of the opening. That is, in the illustration of FIG. 1, a space (accommodating chamber) for accommodating an article to be cooled is formed between the heat insulating door 4 and the partition plate 31 in the heat insulating housing 3. A space (cooling chamber) for cooling the air in the accommodation chamber is formed between the inner wall and the inner wall. Specifically, a suction port 31a is formed below the partition plate 31 (lower side in FIG. 1), and an outlet 31b is formed above the partition plate 31 (upper side in FIG. 1). The evaporator 23 with the defrost heater 12 is arranged on the back side of the mouth 31a, and the fan 32 is arranged on the back side of the outlet 31b. When the fan 32 operates, the air in the accommodation chamber passes through the suction port 31a and is cooled by the evaporator 23 in the cooling chamber, and then returns to the accommodation chamber through the outlet 31b (FIG. 1). (See the white arrow below.) In the illustration of FIG. 1, a drain pan (receiving tray) 33 that receives water generated by melting frost attached to the surface of the evaporator 23 and frost falling from the evaporator 23 is formed at the bottom of the cooling chamber. The water stored in the drain pan 33 is led to the evaporating dish 35 through the pipe 34 in the machine chamber below the heat insulating housing 3 and then evaporates from the evaporating dish 35 to the atmosphere. Yes. In the illustration of FIG. 1, the compressor 11 and the like are disposed in the machine room below the heat insulating casing 3, and the condenser 21 and the capillary tube 22 and the like are disposed on the back side of the heat insulating casing 3. Further, in the illustration of FIG. 1, a temperature sensor (internal temperature sensor) 13 such as a thermistor for detecting the temperature in the heat insulating housing 3 is disposed at the upper part in the heat insulating housing 3.

  As illustrated in FIG. 1, the drain pan heater 19 is a heating device such as an electric heater that heats the drain pan 33 so that water stored in the drain pan 33 does not freeze. As will be described later, the drain pan heater 19 of the present embodiment is energized so as to operate during a period when the refrigeration apparatus 2 is not operating, like the defrost heater 12.

  The heat insulating door 4 is a door that opens or closes the aforementioned opening of the heat insulating housing 3. In particular, when the heat insulating door 4 closes the opening, as illustrated in FIG. 1, the back surface of the heat insulating door 4 and the packing 3 a around the opening are in close contact with each other, thereby isolating the inside of the heat insulating housing 3 from the atmosphere. It has become so. In the illustration of FIG. 1, a display 17 for displaying, for example, the temperature in the heat insulating housing 3 is provided on the front surface of the heat insulating door 4. Further, in the illustration of FIG. 1, either the heat insulating door 4 or the opening of the heat insulating housing 3 includes, for example, a heat insulating door switch (heat insulating) that is turned on when the opening is open and turned off when the opening is closed. Door sensor) 15 is provided.

  The heat insulating housing 3 and the heat insulating door 4 form a storage for storing a cooling target such as blood or medicine.

  As illustrated in FIG. 2, the control board 10 is a control device such as a microcomputer including a CPU 101, a memory 102, a first timer 103a, a second timer 103b, and the like.

  In the example of FIG. 2, the CPU 101 is configured to operate or stop the memory 102, the first timer 103 a, the second timer 103 b, the relay 111 for operating or stopping the compressor 11, and the defrosting heater 12. The relay 112, the relay 113 for operating or stopping the drain pan heater 19, the temperature sensor 13 in the heat insulating housing, the evaporator temperature sensor 14, the heat insulating door switch 15, and the display 17 are collectively controlled. Here, the relay 111 is configured to connect the compressor 11 and the power source 16 in series in the on state, and to block the series connection in the off state, and the relay 112 is connected to the defrost heater 12 and the power source in the on state. 16 is connected in series, and the series connection is cut off in the off state. The relay 113 connects the drain pan heater 19 and the power supply 16 in series in the on state, and cuts off the series connection in the off state. It is like that. As will be described later, the CPU 101, for example, falls within the allowable temperature range (between an upper limit allowable temperature and a lower limit allowable temperature described later) based on a program stored in the memory 102. Therefore, based on the detection result of the temperature sensor 13 in the heat insulating casing, the compressor 11 is operated or stopped, and the defrosting heater 12 is operated or stopped. At that time, the CPU 101 executes a process for operating or stopping the drain pan heater 19 in accordance with the operation rate of the refrigeration apparatus 2 measured by the first timer 103a and the second timer 103b. The operating rate of the refrigeration apparatus 2 is the ratio of the time during which the refrigeration apparatus 2 that repeatedly operates and stops is operating. Processing for operating or stopping the drain pan heater 19 according to the operating rate of the refrigeration apparatus 2 will be described later.

  The memory 102 stores a program for defining a processing procedure described later of the CPU 101, various data used for the processing of the CPU 102, and the like.

  The display 17 includes, for example, the temperature in the heat insulating housing 3 (internal temperature) detected by the heat insulating housing temperature sensor 13, the temperature of the evaporator 23 detected by the evaporator temperature sensor 14, and the opening / closing of the heat insulating door 4. Displays the status. In addition, the display 17 according to the present embodiment is configured by, for example, a touch panel, and an operator can input information. For example, the operator may input various setting information such as a set temperature in the heat insulating casing 3 of the cool box 1, an upper limit allowable temperature, a lower limit allowable temperature of the heat insulating casing 3 described later, and an operating condition of the drain pan heater 19. it can.

=== Example of cold storage operation ===
With reference to FIGS. 3 and 4, an operation example of the cool box 1 having the above-described configuration will be described. 3 is a flowchart showing an example of the processing procedure of the cool box 1 controlled by the CPU 101. FIG. 4 shows the temperature in the heat insulating casing 3, the temperature of the evaporator 23, the operating state of the compressor 11, It is a diagram which shows an example of the time change of the operation state of the defrost heater 12, and the operation state of the drain pan heater 19. FIG.

  As shown in FIG. 3, when the cool box 1 according to the present embodiment starts the process, it is determined whether or not the temperature in the heat insulating casing 3 (the temperature in the box) is equal to or lower than the lower limit allowable temperature (second temperature). Determine (S1000).

  The lower limit allowable temperature of the heat insulating housing 3 is set to a value obtained by subtracting a predetermined temperature (2 ° C.) from the set temperature of the cool box 1, for example. For example, when the set temperature of the cool box 1 is set to 5 ° C., the lower limit allowable temperature of the heat insulating casing 3 is set to 3 ° C. (5 ° C.−2 ° C.). Of course, the lower limit allowable temperature of the heat insulating housing 3 may be set directly from the display 17.

  In addition, similarly to the lower limit allowable temperature of the heat insulating casing 3, the upper limit allowable temperature (first temperature) of the heat insulating casing 3 is, for example, a value obtained by adding a predetermined temperature (2 ° C.) to the set temperature (5 ° C.) of the cool box 1 Set to When the set temperature of the cool box 1 is set to 5 ° C., the upper limit allowable temperature of the heat insulating housing 3 is set to 7 ° C. (5 ° C. + 2 ° C.). Of course, the upper limit allowable temperature of the heat insulating housing 3 may be set directly from the display 17.

  In addition, the value of the range of increase / decrease (the predetermined temperature 2 ° C.) with respect to the set temperature (5 ° C.) of the cool box 1 may be set to an arbitrary value from the display 17.

  The cool box 1 turns off the compressor 11 and turns on the defrost heater 12 and the drain pan heater 19 when the temperature in the heat insulating housing 3 is equal to or lower than the lower limit allowable temperature (second temperature) (S1000). (S1030, S1040). Thereby, the inside of the heat insulation housing | casing 3 is heated and temperature rises gradually.

  On the other hand, when the temperature in the heat insulating casing 3 is not lower than the lower limit allowable temperature (second temperature) (S1000), the cool box 1 turns off the defrost heater 12 and the drain pan heater 19 and turns off the compressor 11. Turn it on (S1010, S1020). Thereby, the inside of the heat insulation housing | casing 3 is cooled and temperature falls gradually.

  In the present embodiment, when the cool box 1 starts operation, the temperature inside the heat insulating housing 3 is equal to or higher than the upper limit allowable temperature of the heat insulating housing 3 as illustrated in FIG. Explained as an example.

  In this case, the cool box 1 first turns off the defrost heater 12 and the drain pan heater 19 and turns on the compressor 11 to cool the inside of the heat insulating casing 3 (S1010, S1020).

  Thereafter, the cool box 1 executes S1080, but since the temperature in the heat insulating casing 3 is equal to or higher than the upper limit allowable temperature, the conditional branch block of S1080 is branched to “≧ upper limit allowable temperature”.

  Then, the cool box 1 determines the operating state of the compressor 11 (S1050). Here, since the compressor 11 is operating, it branches to “ON” and returns to the processing of S1080 again.

  In this manner, the cool box 1 continues the defrost heater 12 = off, the drain pan heater 19 = off, and the compressor 11 = on while the temperature in the heat insulating casing 3 is equal to or higher than the upper limit allowable temperature. Thereby, the temperature in the heat insulation housing | casing 3 falls gradually as shown to (B) of FIG.

  Next, when the temperature in the heat insulating casing 3 is not equal to or higher than the upper limit allowable temperature ((B) in FIG. 4), the cool box 1 branches the conditional branch block of S1080 to “else”. Return to processing. That is, the cool box 1 continues the defrost heater 12 = off, the drain pan heater 19 = off, and the compressor 11 = on. Thereby, the temperature in the heat insulation housing | casing 3 falls gradually as shown to (C) from FIG.

  Next, when the temperature in the heat insulation housing 3 becomes equal to or lower than the lower limit allowable temperature ((C) in FIG. 4), the cold storage 1 branches the conditional branch block of S1080 to “≦ lower limit allowable temperature”.

  Since the compressor 11 is on, the conditional branch block of S1090 is branched to “ON”. The cool box 1 turns off the compressor 11 and turns on the defrost heater 12 (S1100, S1110). Thereby, the inside of the heat insulation housing | casing 3 is heated and temperature rises gradually.

  And the cool box 1 determines whether the operating rate of the freezing apparatus 2 is less than a predetermined value (S1120). The operating rate indicates the ratio of the operating time of the refrigeration apparatus 2 that operates intermittently. The operating rate of the refrigeration apparatus 2 is measured using the first timer 103a and the second timer 103b. Details will be described later.

  When the operation rate of the refrigeration apparatus 2 is equal to or greater than the predetermined value, the cold storage 1 branches the conditional branch block of S1120 to “≧ predetermined value”, turns on the drain pan heater 19 (S1130), and again in S1080. Return to processing. That is, at this time, the cool box 1 controls the temperature in the heat insulating casing 3 by setting the compressor 11 = off, the defrost heater 12 = on, and the drain pan heater 19 = on.

  On the other hand, when the operation rate of the refrigeration apparatus 2 is less than the predetermined value, the cold storage 1 branches the conditional branch block of S1120 to “<predetermined value” and returns to the process of S1080 again. That is, at this time, the cool box 1 controls the temperature in the heat insulating casing 3 by setting the compressor 11 = off, the defrost heater 12 = on, and the drain pan heater 19 = off.

  Thus, when the temperature in the heat insulation housing | casing 3 becomes below a minimum allowable temperature ((C) of FIG. 4), the cold storage 1 which concerns on this embodiment has the operating rate of the freezing apparatus 2 more than predetermined value. In some cases, the compressor 11 is turned off and the defrost heater 12 and the drain pan heater 19 are turned on (S1100, S1110, S1130) to heat the inside of the heat insulating housing 3, but the operating rate of the refrigeration apparatus 2 is increased. When it is less than the predetermined value, the compressor 11 is turned off and the defrost heater 12 is turned on (S1100, S1110), but the drain pan heater 19 is kept off and the inside of the heat insulating casing 3 is heated. .

  Next, when the temperature in the heat insulating casing 3 is not lower than the lower limit allowable temperature ((C) in FIG. 4), the cold storage 1 branches the conditional branch block of S1080 to “else”. And the cool box 1 performs the process of S1080 again as it is, and continues the heating in the heat insulation housing | casing 3. FIG.

  As shown in FIG. 4, during (C) to (D) in FIG. 4, the temperature of the evaporator 23 is equal to or lower than the melting point (0 ° C.) of frost. When the temperature of the evaporator 23 reaches the melting point of the frost ((D) in FIG. 4), the temperature of the evaporator 23 is the melting point of the frost (0) until the melting of the frost adhering to the evaporator 23 is completed. ° C) ((D) to (E) in FIG. 4).

  When the melting of the frost adhering to the evaporator 23 ends ((E) in FIG. 4), the temperature of the evaporator 23 starts to rise again (from (E) to (F) in FIG. 4).

  In this way, when the temperature in the heat insulating casing 3 gradually rises and exceeds the upper limit allowable temperature ((F) in FIG. 4), the cool box 1 branches the conditional branch block of S1080 to “≧ maximum allowable temperature”. Then, the cooling control is started again (from (F) to (G) in FIG. 4).

  In the same manner, the cool box 1 repeats the control for intermittently operating the compressor 11, that is, the refrigeration apparatus 2, so that the temperature detected by the temperature sensor 13 in the heat insulating casing is the upper limit allowable temperature in the heat insulating casing 3. The temperature is set between the first temperature and the second temperature which is the lower limit allowable temperature (see FIGS. 4A to 4J).

  Moreover, the cool box 1 suppresses the attachment of frost to the evaporator 23 by operating the defrost heater 12 during a period when the refrigeration apparatus 2 is not operating.

  By the way, as mentioned above, the cool box 1 according to the present embodiment measures the operating rate of the refrigeration apparatus 2 using the first timer 103a and the second timer 103b.

  The first timer 103a measures the length T1 of one cycle in which the refrigeration apparatus 2 repeats operation and stop once each time. For example, they are the periods (A) to (F) in FIG. 4, the periods (F) to (H), and the periods (H) to (J). On the other hand, the second timer 103b measures the length T2 of the operation period in one cycle in which the refrigeration apparatus 2 repeats operation and stop once each time. For example, they are the periods (A) to (C) in FIG. 4, the periods (F) to (G), and the periods (H) to (I).

  And the cold storage 1 is calculating the operation rate (S1120 of FIG. 3) of the freezing apparatus 2 based on the value of T2 / T1.

  For example, the cool box 1 has an operation period ((A in FIG. 4) of the refrigeration apparatus 2 in a period (for example, (A) to (F) in FIG. 4) in which the refrigeration apparatus 2 that operates intermittently operates and stops once. ) To (C)) is calculated as the operation rate.

  And if this operation rate is less than a predetermined value (for example, less than 75%), the cool box 1 is the period during which the operation of the refrigeration apparatus 2 is stopped in the next cycle ((G) to (G) in FIG. Control is performed so that the operation of the drain pan heater 19 is not performed during the period H) (S1120 in FIG. 3).

  Thereby, while the temperature in the heat insulation housing | casing 3 of the cool box 1 can be controlled more efficiently, power consumption can also be reduced.

  That is, the operating rate of the refrigeration apparatus 2 is less than the predetermined value when the set temperature in the heat insulating casing 3 is originally set to be high, and the water dripped onto the drain pan 33 is difficult to freeze. In addition, since the amount of frost adhering to the evaporator 23 is relatively small, the amount of water dripped onto the drain pan 33 is also small. For this reason, when the operation rate of the refrigeration apparatus 2 is less than the predetermined value, the operation of the drain pan heater 19 is not performed, so that unnecessary operation of the drain pan heater 19 can be omitted. Reduction can be achieved.

  In this case, while the operation of the refrigeration apparatus 2 is stopped, the drain pan heater 19 is stopped until the temperature inside the heat insulating casing 3 reaches the upper limit allowable temperature. The rate of temperature rise can be moderated, and the temperature in the heat insulating housing 3 can be stably maintained.

  Or the cold storage 1 which concerns on this embodiment is the following, when the operation rate of the freezing apparatus 2 of every period becomes less than predetermined value (for example, less than 75%) continuously for a predetermined number of times (for example, 2 times). In the period, control may be performed so that the operation of the drain pan heater 19 is not performed during a period in which the operation of the refrigeration apparatus 2 is stopped (period (G) to (H) in FIG. 4).

  In this way, the drain pan heater 19 is not operated when the operating rate is temporarily lowered below a predetermined value due to, for example, opening / closing of the heat insulating door 4 or a sudden change in the outside air temperature. It is possible to prevent the water from being frozen.

  The predetermined number of times may be three times or more. In this case, as the number of times increases, the time until the drain pan heater 19 does not operate after the operation rate of the refrigeration apparatus 2 becomes less than the predetermined value becomes longer. It becomes possible to more stably control the on / off of 19.

  This predetermined number of times can be set to an optimum value by conducting various experiments. In consideration of the power consumption reduction effect during the period from when the operating rate of the refrigeration apparatus 2 becomes less than the predetermined value until the drain pan heater 19 does not operate, the predetermined number is preferably 1 to 3 times. More preferably, the number of times is set.

  Alternatively, in the cool box 1 according to the present embodiment, the ratio of the operation period of the refrigeration apparatus 2 in one or more continuous cycles (period in which the refrigeration apparatus 2 that operates intermittently operates and stops every predetermined number of times) is a predetermined value. If it becomes less than (for example, less than 75%), the drain pan heater 19 may be controlled not to operate during the period when the operation of the refrigeration apparatus 2 is stopped in the next cycle.

  That is, when the average value of the operating rate of the refrigeration apparatus 2 in one or more consecutive cycles becomes less than a predetermined value (for example, less than 75%), the operation of the refrigeration apparatus 2 is stopped in the next cycle. It may be controlled not to operate the drain pan heater 19 during the period.

  Even in such an embodiment, the drain pan heater 19 is not operated when the operating rate of the refrigeration apparatus 2 temporarily falls below a predetermined value due to, for example, opening / closing of the heat insulating door 4 or a sudden change in the outside air temperature. In addition, it is possible to prevent the water from being frozen.

  Also in such an aspect, the predetermined number of times may be three or more. And also in this case, as the number of times increases, the time until the drain pan heater 19 does not operate after the operation rate of the refrigeration apparatus 2 becomes less than the predetermined value becomes longer, so the effect of reducing power consumption becomes smaller. It becomes possible to control the drain pan heater 19 more stably. Further, in the case of this aspect, the drain pan heater 19 can be stably controlled even when the operating rate of the refrigeration apparatus 2 fluctuates up and down every cycle with a predetermined value in between.

  In any of the above embodiments, the predetermined value of the operating rate of the refrigeration apparatus 2 is 75%, but other values may be used. The predetermined value can be set to an optimum value by performing various experiments and the like, but if the predetermined value is set to a higher value, the operation frequency of the drain pan heater 19 is lowered. For this reason, it becomes possible to further reduce the power consumption of the cool box 1. Conversely, when the predetermined value is set to a lower value, the operation frequency of the drain pan heater 19 increases. For this reason, it becomes possible to suppress the freezing of the water in the drain pan 33 more reliably.

  As a result of various experiments, it is preferable that the value of the predetermined value is set to a value in the range of approximately 60% to 80% because the water in the drain pan 33 is not frozen and the power consumption of the cool box 1 is reduced. Furthermore, it is more preferable to set a value within the range of 70% or more and 80% or less, and a value within the range of 75% ± 2% is even more preferable.

  The operating conditions of the drain pan heater 19 such as the predetermined value (75%) and the predetermined number of times (twice) can be set by the operator from the display 17.

  Alternatively, in the cold storage 1 according to the present embodiment, every time the cumulative value of T1 measured by the first timer 103a reaches a predetermined value, the ratio of the cumulative value of T2 measured by the second timer 103b to the cumulative value of T1 is When it becomes less than a predetermined value (for example, less than 75%), in the next cycle, control may be performed so that the operation of the drain pan heater 19 is not performed during the period in which the operation of the refrigeration apparatus 2 is stopped. . That is, regardless of the intermittent operation cycle of the refrigeration apparatus 2, the operation of the drain pan heater 19 is controlled every predetermined period (for example, 30 minutes) based on the ratio of the operation period of the refrigeration apparatus 2 in the predetermined period. Also good.

  In this way, the drain pan heater 19 is not operated when the operating rate is temporarily lowered below a predetermined value due to, for example, opening / closing of the heat insulating door 4 or a sudden change in the outside air temperature. It is possible to prevent the water from being frozen.

  As mentioned above, although the structure and operation | movement of the cool box 1 which concerns on this embodiment were demonstrated, according to the cool box 1 which concerns on this embodiment, the ratio of the operation period of the freezing apparatus 2 which operate | moves intermittently becomes less than predetermined value. In such a case, control is performed so that the operation of the drain pan heater 19 is not performed during the period in which the operation of the refrigeration apparatus 2 is stopped. Thereby, while the temperature in the heat insulation housing | casing 3 of the cool box 1 can be controlled more efficiently, power consumption can also be reduced. Further, while the operation of the refrigeration apparatus 2 is stopped, the drain pan heater 19 is stopped until the temperature inside the heat insulating casing 3 reaches the upper limit allowable temperature. The speed can be reduced, and the temperature in the heat insulating housing 3 can be maintained more stably.

  Here, the cool box 1 according to the present embodiment, when the ratio of the operation period of the refrigeration apparatus 2 in the period in which the refrigeration apparatus 2 that operates intermittently operates and stops a predetermined number of times becomes less than a predetermined value, You may make it determine with the ratio of the operation period of the freezing apparatus 2 having become less than predetermined value. That is, when the period during which the refrigeration apparatus 2 that operates intermittently operates and stops once is one cycle, and the average value of the operating rate of the refrigeration apparatus 2 in one or more consecutive cycles is less than a predetermined value. The ratio of the operation period of the refrigeration apparatus 2 may be determined to be less than a predetermined value. According to such an aspect, the drain pan heater 19 is operated when the operating rate of the refrigeration apparatus 2 temporarily falls below a predetermined value due to, for example, opening / closing of the heat insulating door 4 or a sudden change in the outside air temperature. Therefore, it is possible to prevent the water from being frozen.

  Alternatively, in the cool box 1 according to the present embodiment, the ratio of the operation period of the refrigeration apparatus 2 in the period in which the refrigeration apparatus 2 that operates intermittently operates and stops once becomes less than a predetermined value continuously a predetermined number of times. In this case, it may be determined that the ratio of the operation period of the refrigeration apparatus 2 is less than a predetermined value. Even in such an embodiment, when the operation rate of the refrigeration apparatus 2 temporarily falls below a predetermined value due to the opening / closing of the heat insulating door 4 or a sudden change in the outside air temperature, the drain pan heater 19 is not operated. It is possible to prevent the water from being frozen.

  Moreover, it is preferable that the predetermined number of times in each of the above embodiments is two. In this way, the drain pan heater 19 can be stably controlled and the operation of the refrigeration apparatus 2 even when the operating rate of the refrigeration apparatus 2 fluctuates up and down across a predetermined value. Since the drain pan heater 19 can be prevented from operating in a relatively short time after the rate becomes less than the predetermined value, the power consumption reduction effect of the cool box 1 can be improved.

  Furthermore, the predetermined value in each of the above embodiments is preferably a value within the range of 75% ± 2%. In this way, the water in the drain pan 33 is not frozen, and the power consumption of the cool box 1 can be reduced.

  The above-described embodiment is intended to facilitate understanding of the present invention, and is not intended to limit the present invention. The present invention can be changed and improved without departing from the gist thereof, and the present invention includes equivalents thereof.

  In the above-described embodiment, the defrost heater 12 and the drain pan heater 19 are heating devices that perform a heating operation by energization, but are not limited thereto.

  In the above-described embodiment, the operation or stop of the compressor 11, the defrost heater 12, and the drain pan heater 19 is controlled by driving the relay 111, the relay 112, and the relay 113. However, the present invention is not limited to this. For example, the control may be performed using an element such as a thyristor or a triac.

  In the above-described embodiment, the evaporator 23 is disposed in the space (cooling chamber) partitioned by the partition plate 31 in the heat insulating housing 3, but is not limited to this, and the partition plate 31 may be omitted.

DESCRIPTION OF SYMBOLS 1 Cold storage 2 Refrigeration apparatus 3 Heat insulation housing | casing 3a Packing 4 Heat insulation door 10 Control board 11 Compressor 12 Defrost heater 13 Temperature sensor 14 in a heat insulation housing Evaporator temperature sensor 15 Heat insulation door switch 16 Power supply 17 Display 19 Drain pan heater 21 Condenser 22 Capillary tube 23 Evaporator 31 Partition plate 31a Suction port 31b Air outlet 32 Fan 33 Drain pan 34 Pipe 35 Evaporating dish 101 CPU
102 Memory 103a First timer 103b Second timer 111 Relay 112 Relay 113 Relay

Claims (5)

A storage for storing the object to be cooled;
A cooling device for cooling the inside of the storage by evaporating the refrigerant with an evaporator;
An internal temperature sensor for detecting the internal temperature of the storage;
A first heater for melting frost attached to the evaporator;
A drain pan receiving water droplets or frost dripping from the evaporator;
A second heater for heating the drain pan in order to suppress freezing of water droplets stored in the drain pan or to melt frost;
The cooling device is operated intermittently so that the temperature detected by the internal temperature sensor is between the first temperature that is the upper limit allowable temperature and the second temperature that is the lower limit allowable temperature in the storage. A control device for operating the first heater and the second heater during a period when the operation of the cooling device is stopped;
In a refrigerator with
When the ratio of the operation period of the cooling device in the predetermined period is less than a predetermined value, the control device does not perform the operation of the second heater in the period in which the operation of the cooling device is stopped. A cool box that is controlled. 2. The cool storage according to claim 1, wherein a ratio of an operation period of the cooling device in a period in which the cooling device that operates intermittently operates and stops a predetermined number of times is less than the predetermined value. The cooler is characterized in that the ratio of the operation period of the cooling device is determined to be less than the predetermined value. The cold storage according to claim 1, wherein the control device is configured such that a ratio of an operation period of the cooling device in a period in which the cooling device that operates intermittently operates and stops once is continuously a predetermined number of times. When the temperature is less than the predetermined value, it is determined that the ratio of the operation period of the cooling device is less than the predetermined value. The cool box according to claim 2 or 3, wherein the predetermined number of times is two. The cool box according to any one of claims 1 to 4, wherein the predetermined value is a value within a range of 75% ± 2%.

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