Refrigeration device for container

Abstract

A refrigeration device (10) for a container is provided with a control unit (100) that, during a cooling operation for cooling the inside of a container (1), controls pressure equalizing mechanisms (40, 80) so as to equalize the pressure between the inside and outside of the container (1) when the pressure detected by a pressure detection unit (P) is lower than a predetermined first pressure that is smaller than atmospheric pressure.

Description

Technical Field

[0001] This disclosure relates to a refrigeration device for a container. Background Technology

[0002] To date, refrigeration units for containers, which cool the interior of shipping containers, are known. These containers are used to store food and other goods. The refrigeration units cool the air inside the container through an evaporator. As a result, the temperature around the stored goods is maintained below a specified level.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent No. 5625582 Summary of the Invention

[0006] -The technical problem the invention aims to solve-

[0007] If the air inside a container is rapidly cooled by the container's refrigeration unit, the pressure inside the container will decrease. As a result, the pressure inside the container becomes negative pressure, which is lower than atmospheric pressure, potentially causing the container to break.

[0008] This disclosure suppresses container damage caused by a decrease in pressure inside the container.

[0009] - Technical solutions used to solve technical problems -

[0010] The first aspect relates to a refrigeration unit for a container, comprising: a pressure detection unit P that detects the pressure inside a container 1; pressure equalization mechanisms 40 and 80 that equalize the pressure inside and outside the container 1; and a control unit 100 that, during cooling operation to cool the interior of the container 1, controls the pressure equalization mechanisms 40 and 80 to perform a pressure equalization operation to equalize the pressure inside and outside the container 1 when the pressure detected by the pressure detection unit P is lower than a predetermined first pressure less than atmospheric pressure. Here, the "pressure detection unit" includes not only a unit that directly detects pressure using sensors, but also a unit that indirectly detects pressure using inferred pressure indicators.

[0011] In the first aspect, during the cooling operation that cools the interior of container 1, when the pressure inside container 1 falls below a predetermined first pressure, the control unit 100 causes the pressure equalization mechanisms 40 and 80 to perform a pressure equalization operation. During this operation, the pressure equalization mechanisms 40 and 80 equalize the pressure inside and outside of container 1, thus preventing the internal pressure of container 1 from becoming negative. As a result, damage to container 1 can be prevented.

[0012] Secondly, based on the first aspect, the pressure equalization mechanisms 40 and 80 are ventilation devices 40 for ventilating the container 1, and the ventilation devices 40 introduce air from outside the container 1 into the interior of the container 1 during the pressure equalization operation.

[0013] In the second aspect of the pressure equalization operation, the ventilation device 40, which acts as the pressure equalization mechanism, introduces air from outside the container 1 into the interior of the container 1. As a result, it is possible to prevent the internal pressure of the container 1 from becoming negative, thereby preventing damage to the container 1.

[0014] Thirdly, based on the first aspect, the pressure equalization mechanisms 40 and 80 are regulating devices 80 that adjust the composition of the air inside the container 1. During the pressure equalization operation, the regulating device 80 introduces air from outside the container 1 into the interior of the container 1.

[0015] In the third aspect of the pressure equalization operation, the regulating device 80, which acts as the pressure equalization mechanism, introduces air from outside the container 1 into the interior of the container 1. As a result, it is possible to prevent the internal pressure of the container 1 from becoming negative, thereby preventing damage to the container 1.

[0016] In the fourth aspect, based on any one of the first to third aspects, during the pressure equalization operation, when the pressure detected by the pressure detection unit P is higher than a predetermined second pressure that is less than atmospheric pressure, the control unit 100 terminates the pressure equalization operation.

[0017] In the fourth aspect, during the pressure equalization operation, when the pressure inside container 1 exceeds a predetermined first pressure, the control unit 100 terminates the pressure equalization operation. This rapidly suppresses the temperature rise of the air inside container 1 caused by the pressure equalization operation.

[0018] Fifthly, based on the fourth aspect, when the pressure inside the container 1 is higher than a predetermined first pressure and the temperature of the air inside the container 1 is lower than a predetermined temperature, the control unit 100 terminates the pressure equalization operation.

[0019] In the fifth aspect, the pressure equalization operation is terminated when the pressure inside container 1 exceeds a predetermined first pressure and the temperature of the air inside container 1 falls below a predetermined temperature. If the pressure equalization operation is terminated when the air temperature inside container 1 is high, the air temperature will further decrease during cooling operation, potentially causing the negative pressure inside container 1 to rise again. In contrast, in this invention, since the pressure equalization operation is terminated only after the air temperature inside container 1 has decreased, the risk of the negative pressure inside container 1 rising again during subsequent cooling operation can be suppressed. As a result, damage to container 1 can be prevented.

[0020] The sixth aspect, based on any one of the first to fifth aspects, during the initial cooling operation after the container refrigeration unit is started, when the pressure detected by the pressure detection unit P is lower than a predetermined first pressure less than atmospheric pressure, the control unit 100 controls the pressure equalization mechanisms 40 and 80 to perform a first pressure equalization action as the pressure equalization action.

[0021] In the sixth aspect, during the initial cooling operation after the container refrigeration unit is started, a first pressure equalization operation is performed when the pressure detected by the pressure detection unit P is lower than a predetermined first pressure lower than atmospheric pressure. Therefore, even if the temperature of the air inside container 1 drops sharply due to the initial cooling operation, damage to container 1 can be prevented.

[0022] The seventh aspect, based on any one of the first to fifth aspects, involves the control unit 100 executing a second pressure equalization operation as the pressure equalization operation when the pressure detected by the pressure detection unit P is lower than a predetermined first pressure less than atmospheric pressure after the door D of the container 1 is opened or closed during cooling operation.

[0023] In the seventh aspect, after door D is temporarily opened during cooling operation, a second pressure equalization operation is performed when the pressure detected by pressure detection unit P is lower than a predetermined first pressure that is less than atmospheric pressure. Therefore, even if hot air enters container 1 when door D is opened and this air is rapidly cooled, damage to container 1 can be prevented.

[0024] The eighth aspect, based on the seventh aspect, involves the following: during the initial cooling operation after the container refrigeration unit is started, when the pressure detected by the pressure detection unit P is lower than a predetermined first pressure less than atmospheric pressure, the control unit 100 controls the pressure equalization mechanisms 40 and 80 to perform a first pressure equalization action as the pressure equalization action. In the second pressure equalization action, the pressure equalization mechanisms 40 and 80 introduce air from outside the container 1 into the interior of the container 1 at a flow rate greater than that of the first pressure equalization action.

[0025] In the eighth aspect, during the second pressure equalization operation, the pressure equalization mechanisms 40 and 80 introduce external air with a flow rate greater than that during the first pressure equalization operation into the interior of container 1. This is because, after door D is temporarily opened, the warmer air inside container 1 is cooled, and the internal pressure of container 1 is more likely to drop rapidly compared to the initial cooling operation after the container's refrigeration unit is started.

[0026] In the ninth aspect, based on any one of the first to eighth aspects, the control unit 100 controls the pressure equalization mechanisms 40 and 80 during cooling operation so that the flow rate of air introduced from the outside of the container 1 to the inside decreases as the temperature of the air inside the container 1 decreases.

[0027] In the ninth aspect, when the temperature of the air inside container 1 is high, making it easy for the negative pressure inside container 1 to rise, the amount of external air introduced increases. When the temperature of the air inside container 1 is low, and the cooling load easily increases with the introduction of external air, the amount of external air introduced decreases.

[0028] In the tenth aspect, based on any one of the first to ninth aspects, the pressure detection unit P is a pressure sensor 53.

[0029] In the tenth aspect, the internal pressure of container 1 is detected by pressure sensor 53.

[0030] The eleventh aspect, based on any one of the first to ninth aspects, includes a drain pipe 60 that discharges condensate generated inside the container 1 to the outside of the container 1, and has a trap 61 for storing the condensate, wherein the pressure detection unit P detects the pressure inside the container 1 based on the water level in the trap 61.

[0031] In the eleventh aspect, the pressure inside the container 1 is detected based on the water level in the trap 61 of the drain pipe 60. This is because if the pressure inside the container 1 changes, the water level in the trap 61 will also change.

[0032] The twelfth aspect, based on any one of the first to ninth aspects, is that the pressure detection unit P detects the pressure inside the container 1 based on the temperature of the air inside the container 1 before or at the start of the cooling operation, and the temperature of the air inside the container 1 during the cooling operation.

[0033] In the twelfth aspect, the pressure inside container 1 is measured based on the air temperature inside container 1 before and after the start of cooling operation. This is because if the air temperature inside container 1 decreases due to cooling operation, the pressure inside container 1 will change.

[0034] The thirteenth aspect, based on any one of the first to ninth aspects, includes gas sensors 71 and 72 for detecting the concentration of gas components in the air inside the container 1, and the pressure detection unit P detects the pressure inside the container 1 based on the concentration detected by the gas sensors 71 and 72 before or at the start of the cooling operation, and the concentration detected by the gas sensors 71 and 72 during the cooling operation.

[0035] In the thirteenth aspect, the pressure inside container 1 is detected based on the concentrations detected by gas sensors 71 and 72 before and after the start of cooling operation. This is because there is a correlation between the concentrations detected by gas sensors 71 and 72 and the pressure inside container 1. Attached Figure Description

[0036] Figure 1 This is a perspective view of the container refrigeration unit involved in the implementation method as seen from the front.

[0037] Figure 2 This is a longitudinal sectional view of a refrigeration unit for containers.

[0038] Figure 3 This is a block diagram of the main equipment of a container refrigeration unit.

[0039] Figure 4 This is a diagram of the piping system for a refrigeration unit used in shipping containers.

[0040] Figure 5 This is a simplified front view diagram of the ventilation device. Figure 5 (A) shows the lid in the closed position. Figure 5 (B) shows the lid in the middle position. Figure 5 (C) shows the lid in the fully open position.

[0041] Figure 6 This is a 3D view of the container from the rear (door side).

[0042] Figure 7 This is a flowchart illustrating the control actions of the pressure equalization mechanism.

[0043] Figure 8 This is a flowchart illustrating the control of the pressure equalization mechanism in the first mode.

[0044] Figure 9 This is a flowchart illustrating the control of the pressure equalization mechanism in the second mode.

[0045] Figure 10 This is a simplified structural diagram of the drainage pipe and pressure detection unit of Modified Example 1A, which shows the state in which the internal pressure of the container is equal to the external pressure.

[0046] Figure 11 This is a simplified structural diagram showing the drainage pipe and pressure detection unit of Modified Example 1A, which shows the state where the internal pressure of the container is less than the external pressure.

[0047] Figure 12 It is equivalent to variation 1C Figure 3 The image.

[0048] Figure 13 It is equivalent to variation 1D Figure 3 The image.

[0049] Figure 14 It is equivalent to variation 2A Figure 2 The image.

[0050] Figure 15 It is equivalent to variation 2B Figure 3 The image. Detailed Implementation

[0051] The embodiments of this disclosure will now be described in detail with reference to the accompanying drawings. It should be noted that this disclosure is not limited to the embodiments shown below, and various modifications can be made without departing from the technical concept of this disclosure. The accompanying drawings are for conceptual illustration of this disclosure; therefore, for ease of understanding, dimensions, scales, or quantities may sometimes be exaggerated or simplified as needed.

[0052] (1) Overall structure of refrigeration unit for container

[0053] The refrigeration unit 10 for the container will be described below. It should be noted that in the following description, statements related to "front," "rear," "upper," "lower," "right," and "left" will be expressed in words starting with "front," "rear," "upper," "lower," "right," and "left." Figure 1 The direction indicated by the arrow in the image is the reference.

[0054] like Figure 1 and Figure 2 As shown, a refrigeration unit 10 is installed in container 1. Container 1 is used for maritime transport. Container 1 is a refrigerated container that cools the air inside. Container 1 has a container body 2 and a refrigeration unit 10. The container body 2 stores food, plants, and other items. The refrigeration unit 10 cools the air in the internal space 3 of the container body 2. Figure 2 As shown, a front opening 4 is formed on the front side of the container body 2. The container refrigeration unit 10 is installed on the container body 2 in such a way that it seals the front opening 4 of the container body 2.

[0055] like Figure 3 As shown, the container refrigeration unit 10 has a cooling unit 10A for cooling the container interior space 3 and a ventilation device 40 for ventilating the container interior space 3.

[0056] (2) Cooling unit

[0057] like Figure 1 and Figure 2As shown, the cooling unit 10A has a housing 11. The housing 11 forms the cover of the front opening 4 of the container body 2. The housing 11 has a housing body 12 and a partition 13. The housing body 12 separates the external space 5 of the container body 2 from the internal space 3. The partition 13 is located on the rear side (rear side) of the housing 11.

[0058] Cooling unit 10A has a compressor 25, an external heat exchanger 26, and an external fan 27 as equipment located outside the enclosure. Cooling unit 10A also has an internal heat exchanger 29 and an internal fan 30 as equipment located inside the enclosure.

[0059] (2-1) Shell body

[0060] like Figure 2 As shown, the housing body 12 has a flat plate portion 12a and a recessed portion 12b. The flat plate portion 12a is formed on the upper part of the housing body 12 and is substantially flush with the front opening 4 of the housing 11. Figure 1 As shown, an inspection window 22 is provided on the flat plate portion 12a. The inspection window 22 is located on the right side of the flat plate portion 12a. The inspection window 22 is a transparent window used to view the interior of the housing body 12.

[0061] A recess 12b is formed in the lower part of the housing 11. The recess 12b is recessed rearward from the lower end of the flat plate 12a. An external storage space 14 is formed on the front side of the recess 12b. An internal storage space 15 is formed above the recess 12b and between the flat plate 12a and the partition 13. The lower end of the recess 12b forms a bottom plate 12c. The bottom plate 12c extends across the left and right ends of the housing body 12.

[0062] The main body 12 is constructed by stacking an outer shell 16, an insulation layer 17, and an inner shell 18 along the thickness direction (front-to-back direction). The outer shell 16 faces the external space 5. The inner shell 18 faces the interior. The insulation layer 17 is disposed between the outer shell 16 and the inner shell 18. The outer shell 16 is made of aluminum. The inner shell 18 is made of fiber-reinforced plastic (FRP). The insulation layer 17 is made of foamed resin.

[0063] (2-2) Partitions and air passages

[0064] like Figure 2As shown, partition 13 is a plate-shaped component located behind recess 12b. Partition 13 extends vertically and is spaced apart from the rear surface of recess 12b by a predetermined interval. An internal passage 19 for airflow within the container is formed between the main body 12 and partition 13. An inlet 20 is formed between the upper end of partition 13 and the upper wall 2a of the container body 2. The inlet 20 connects the internal space 3 with the inflow end of the internal passage 19. An outlet 21 is formed between the lower end of partition 13 and the lower wall 2b of the container body 2. The outlet 21 connects the internal space 3 with the outflow end of the internal passage 19.

[0065] (2-3) Equipment in the space outside the box

[0066] The external storage space 14 houses a compressor 25, an external heat exchanger 26, and an external fan 27. The compressor 25 is mounted on the bottom plate 12c of the housing 11. The compressor 25 is positioned in the lower part of the external storage space 14. The compressor 25 is also positioned on the right side of the external storage space 14.

[0067] The external fan 27 is located in the upper part of the external storage space 14. The external fan 27 is a propeller fan. Figure 2 As shown, an external passage 28 for airflow from outside the box is formed on the back side of the external fan 27.

[0068] The external heat exchanger 26 is positioned within the external storage space 14 at a height between the external fan 27 and the compressor 25. The external heat exchanger 26 is located within the external passageway 28. The external heat exchanger 26 is a finned tube heat exchanger.

[0069] (2-4) Equipment inside the box

[0070] An internal heat exchanger 29 and an internal fan 30 are installed in the internal storage space 15. The internal heat exchanger 29 is supported by the shell 11 in a manner that spans across the main shell 12 and the partition 13. The internal heat exchanger 29 is a finned tube heat exchanger.

[0071] (2-5) Refrigerant circuit

[0072] like Figure 4 As shown, the cooling unit 10A has a refrigerant circuit R. The refrigerant circuit R is filled with refrigerant. The refrigerant circuit R performs a vapor compression refrigeration cycle by circulating the refrigerant. For example, propane or carbon dioxide, which are natural refrigerants, can be used in the refrigerant circuit R.

[0073] The refrigerant circuit R mainly includes a compressor 25, an external heat exchanger 26, an expansion valve 31, and an internal heat exchanger 29.

[0074] Compressor 25 compresses the refrigerant that has been drawn in. Compressor 25 then sprays out the compressed refrigerant. A discharge pipe 32 is connected to the discharge section of compressor 25. A suction pipe 33 is connected to the suction section of compressor 25. A liquid receiver 34 is provided on the suction pipe 33. The liquid receiver 34 is a container for storing liquid refrigerant.

[0075] The external heat exchanger 26 facilitates heat exchange between the refrigerant flowing inside and the outside air. The gas-side end of the external heat exchanger 26 is connected to the discharge pipe 32. The liquid-side end of the external heat exchanger 26 is connected to the liquid-side end of the internal heat exchanger 29 via a liquid pipe 35. The external heat exchanger 26 functions as a heat exchanger (condenser) that releases heat from the refrigerant to the air.

[0076] An expansion valve 31 is installed on the liquid line 35. The expansion valve 31 is an expansion mechanism that reduces the pressure of the high-pressure refrigerant to that of the low-pressure refrigerant. The expansion valve 31 is an electronically adjustable expansion valve. The expansion mechanism can also be a capillary tube or an expander. A receiver 36 is installed in the portion of the liquid line 35 located between the external heat exchanger 26 and the expansion valve 31. The receiver 36 is a container for storing the remaining refrigerant in the refrigerant circuit R.

[0077] The internal heat exchanger 29 allows the refrigerant flowing inside it to exchange heat with the air inside the chamber. The air-side end of the internal heat exchanger 29 is connected to the suction pipe 33. The internal heat exchanger 29 functions as an evaporator that allows the refrigerant to absorb heat from the air.

[0078] The refrigerant circuit R has a bypass pipe 37. The inlet end of the bypass pipe 37 is connected to the outlet pipe 32, and the outlet end of the bypass pipe 37 is connected to the liquid pipe 35. The bypass pipe 37 allows the refrigerant injected from the compressor 25 to bypass the external heat exchanger 26 and be delivered to the internal heat exchanger 29.

[0079] A first valve 38 and a second valve 39 are provided in the refrigerant circuit R. The first valve 38 is located between the discharge side of the compressor 25 and the gas side of the external heat exchanger 26, and is positioned downstream of the connection of the bypass pipe 37. The second valve 39 is located on the bypass pipe 37. Both the first valve 38 and the second valve 39 are electromagnetic switching valves. The first valve 38 and the second valve 39 can be flow regulating valves with adjustable opening degrees.

[0080] (3) Ventilation device

[0081] Reference Figure 1 , Figure 2 as well as Figure 5The structure of the ventilation device 40 will be described. The ventilation device 40 ventilates the internal space 3 of the container body 2. In this embodiment, the ventilation device 40 has the functions of supplying air from outside the container (which is outdoor air) to the internal space 3 and exhausting air from inside the container to the external space 5. In this embodiment, the ventilation device 40 also functions as a pressure equalization mechanism.

[0082] like Figure 1 As shown, the ventilation device 40 is arranged on the left side of the flat plate portion 12a of the housing body 12. Figure 2 As shown, the ventilation device 40 is provided at the ventilation mounting port 6, which is formed on the front side of the housing body 12. The ventilation mounting port 6 penetrates the housing body 12 in the front-rear direction. The ventilation mounting port 6 is formed by passing through the outer shell 16, the insulation layer 17, and the inner shell 18.

[0083] Inside the ventilation device 40, an air supply passage 41 and an exhaust passage 42 are formed. The air supply passage 41 and the exhaust passage 42 connect the internal space 3 of the enclosure to the external space 5. Specifically, the inflow end of the air supply passage 41 connects to the external space 5. The outflow end of the air supply passage 41 connects to the primary side (upstream side) of the internal fan 30 in the internal passage 19. The inflow end of the exhaust passage 42 connects to the secondary side (downstream side) of the internal fan 30 in the internal passage 19. The outflow end of the exhaust passage 42 connects to the external space 5.

[0084] The ventilation device 40 includes a ventilation fan. The ventilation fan is composed of the aforementioned in-box fan 30. In this embodiment, the in-box fan 30 is used both in the ventilation device 40 and in the cooling unit 10A. When the in-box fan 30 is driven, outside air in the outside space 5 is supplied to the inside space 3 through the air supply passage 41. At the same time, inside air in the inside space 3 is exhausted to the outside space 5 through the exhaust passage 42.

[0085] like Figure 2 and Figure 5 As shown, an air supply connection port 41a is formed at the end of the air supply passage 41 on the side of the outer space 5. An exhaust connection port 42a is formed at the end of the exhaust passage 42 on the side of the outer space 5.

[0086] like Figure 2 As shown, the ventilation device 40 includes a motor 43, a drive shaft 44 driven by the motor 43, and an openable / closed cover 45 connected to the drive shaft 44. The motor 43 and the drive shaft 44 are housed within the housing of the ventilation device 40. The motor 43 is a stepper motor. The drive shaft 44 is directly connected to the motor 43. Alternatively, the drive shaft 44 may be indirectly connected to the motor 43 via a pinion or gear.

[0087] The opening / closing cover 45 is located on the front side of the drive shaft 44. The opening / closing cover 45 is configured to rotate about the axis of the drive shaft 44. The opening / closing cover 45 opens and closes the air supply passage 41 and the exhaust passage 42 according to its rotation angle. The opening / closing cover 45 constitutes an opening adjustment mechanism for adjusting the opening degree of the air supply passage 41 and the exhaust passage 42.

[0088] like Figure 5 As shown, an air supply opening 46 and an exhaust opening 47 are formed on the opening / closing cover 45. The air supply opening 46 is configured to communicate with the air supply connection port 41a. The exhaust opening 47 is configured to communicate with the exhaust connection port 42a.

[0089] Specifically, when the opening and closing of the cover is at 45 degrees... Figure 5 When the first rotation angle (closed position) is shown in (A), the entire gas supply port 41a is covered by the opening and closing cover 45, and the entire exhaust port 42a is covered by the opening and closing cover 45. Therefore, the gas supply passage 41 and the exhaust passage 42 are in a fully closed state.

[0090] When the lid is open / closed at 45 degrees Figure 5 At the second rotation angle (fully open position) shown in (C), the entire air supply port 41a overlaps with the air supply opening 46, and the entire exhaust port 42a overlaps with the exhaust opening 47. Therefore, the air supply passage 41 and the exhaust passage 42 are in the fully open state.

[0091] When the lid is open / closed at 45 degrees Figure 5 (B) At the third rotation angle (intermediate position), a portion of the air supply port 41a overlaps axially with the air supply opening 46, and a portion of the exhaust port 42a overlaps axially with the exhaust opening 47. The intermediate position is the position between the closed position and the fully open position. Therefore, the opening degree of the air supply passage 41 and the exhaust passage 42 is smaller than that of the fully open state.

[0092] The opening degree of the air supply passage 41 and the exhaust passage 42 is adjusted by adjusting the rotation angle of the opening and closing cover 45 from the closed position to the fully open position, thereby adjusting the air exchange volume of the ventilation device 40.

[0093] (4) Sensors

[0094] The container refrigeration unit 10 has multiple sensors. For example... Figure 2 and Figure 3 As shown, multiple sensors include an internal temperature sensor 51, an external temperature sensor 52, and a pressure sensor 53.

[0095] The internal temperature sensor 51 detects the temperature of the air inside container 1. The internal temperature sensor 51 is located upstream of the internal fan 30 in the airflow direction within the internal passage 19. The internal temperature sensor 51 is positioned near the inlet 20 of the internal passage 19.

[0096] The external temperature sensor 52 detects the temperature of the air outside the container 1. The external temperature sensor 52 is positioned upstream of the external heat exchanger 26 in the airflow direction within the external passage 28. The external temperature sensor 52 is located near the inlet of the external passage 28.

[0097] Pressure sensor 53 is an example of pressure detection unit P. Pressure sensor 53 detects the pressure inside container 1. Pressure sensor 53 is arranged in internal passage 19. Pressure sensor 53 is arranged, for example, in internal passage 19 upstream of internal fan 30 in the airflow direction, but it can also be arranged in internal passage 19 downstream of internal fan 30 in the airflow direction.

[0098] (5) Control and Operation Department

[0099] like Figure 3 As shown, the container refrigeration unit 10 has a control unit 100. The control unit 100 controls the cooling unit 10A and the ventilation unit 40. The control unit 100 includes a microprocessor, electrical circuits, and electronic circuits. The microprocessor includes a CPU (Central Processing Unit), memory, a communication interface, analog input / output, and contact input / output interfaces. The memory stores various programs executed by the CPU and the data used by the programs.

[0100] The control unit 100 controls the various devices in the cooling unit 10A. Specifically, the control unit 100 controls the speed of the compressor 25, the speed of the internal fan 30, the speed of the external fan 27, and the opening degree of the expansion valve 31. The control unit 100 controls the motor 43 of the ventilation device 40. The control unit 100 adjusts the opening degree of the air supply passage 41 and the exhaust passage 42 of the ventilation device 40, thereby adjusting the ventilation volume of the ventilation device 40.

[0101] like Figure 3As shown, the container refrigeration unit 10 has an operation unit 110. The operation unit 110 may consist of, for example, a touch panel, remote control, or switch mounted on the container refrigeration unit 10. The operation unit 110 may also be a communication terminal connected to the container refrigeration unit 10 via a network. By operating the operation unit 110, the user can switch the operating mode of the container refrigeration unit 10 or change the set values ​​for each operating mode. The set values ​​include the target temperature of the container interior space 3.

[0102] (6) Overview of cooling operation

[0103] The container is cooled by the refrigeration unit 10. The cooling operation is an operation mode performed by the user or others operating the operation unit 110.

[0104] During cooling operation, a refrigeration cycle is performed. In this cycle, the refrigerant, compressed in the compressor 25, condenses in the external heat exchanger 26, then depressurizes in the expansion valve 31 and evaporates in the internal heat exchanger 29. Air flowing from the internal space 3 to the internal passage 19 is cooled in the internal heat exchanger 29, which functions as an evaporator. The cooled air is then sent back to the internal space 3. During cooling operation, the control unit 100 controls the speed of the compressor 25 based on the temperature difference between the internal air temperature and the target temperature in the internal space 3.

[0105] During cooling operation, the control unit 100 controls the compressor 25 to bring the temperature of the air inside the chamber to the target temperature. When the temperature of the air inside the chamber reaches the target temperature (temperature control off temperature, for example -18°C), the control unit 100 stops the compressor 25. As a result, the heat exchanger 29 inside the chamber is essentially stopped (temperature control off state). Then, when the temperature of the air inside the chamber reaches a predetermined temperature higher than the target temperature (temperature control on temperature, for example -16°C), the control unit 100 starts the compressor 25, causing the heat exchanger 29 to function as an evaporator. The control unit 100 controls the rotational speed of the compressor 25 to regulate the evaporation temperature of the heat exchanger 29. As a result, the temperature of the air inside the chamber is maintained within the predetermined target range. The temperature control off temperature is equivalent to the set temperature input using the operation unit 110. The temperature control on temperature is the value obtained by adding the predetermined temperature (for example, 2°C) to the set temperature.

[0106] (7) Countermeasures to prevent container damage during cooling operation

[0107] (7-1) Technical issues

[0108] During the aforementioned cooling operation, the air inside the container is cooled, causing its temperature to decrease. If the air temperature decreases during this cooling process, the reduced volume of air inside the container leads to a drop in pressure inside container 1, sometimes resulting in a negative pressure lower than atmospheric pressure. Consequently, the negative pressure inside container 1 can exceed its pressure resistance, causing container 1 to break. Breakage of container 1 can refer, for example, to deformation of the container body 2 caused by the negative pressure inside container 1.

[0109] In particular, during cooling operation, the pressure inside container 1 drops sharply during the following two periods.

[0110] The first period is the initial pull-down operation period. The initial pull-down operation is the initial cooling operation after the container refrigeration unit 10 is started. In other words, the initial pull-down operation is the initial cooling operation after the power to the container refrigeration unit 10 is turned on. At the start of the initial pull-down operation, the temperature of the air inside the container is close to the outside air temperature, which is relatively high. During the initial pull-down operation, the relatively high-temperature air inside the container is cooled to a temperature suitable for refrigerating or freezing the object. For example, if the temperature of the air inside the container at the start of the initial pull-down operation is 30°C, sometimes the air is cooled to -12°C, which is the target temperature. In this way, if the relatively high-temperature air inside the container is cooled with a large temperature difference, the pressure inside the container 1 will decrease, causing the negative pressure to increase.

[0111] The second period is the period after the door D of container 1 is temporarily opened during cooling operation. For example... Figure 6As shown, container 1 has a door D for loading and unloading objects. Door D is located, for example, on the rear side 7 of container 1. Door D opens and closes an opening formed on the rear side that communicates with the interior space 3. During cooling operation, the temperature of the air inside the container is maintained within a target range, namely, between the aforementioned temperature-controlled closing temperature (-18°C) and temperature-controlled opening temperature (-16°C). Suppose that when the internal heat exchanger 29 is in the temperature-controlled closed state, an operator temporarily opens door D of container 1 for some purpose and then closes door D again. When door D is opened, air from outside container 1 enters the interior of container 1. The temperature of the air entering the interior from outside container 1 is higher than the temperature of the air inside container 1 (e.g., -18°C) (e.g., 30°C). As a result, the air that has entered is rapidly cooled by the surrounding air inside container 1. Furthermore, if the temperature of the air inside container 1 is higher than the temperature-controlled opening temperature due to the entry of outside air, compressor 25 operates, and internal heat exchanger 29 becomes temperature-controlled open. As a result, the incoming air is rapidly cooled by the internal heat exchanger 29. As described above, during cooling operation, if door D is opened or closed, the pressure inside container 1 drops sharply, causing a rise in negative pressure. This problem becomes particularly pronounced if door D is opened or closed while the internal heat exchanger 29 is in a temperature-controlled closed state.

[0112] Furthermore, the problem of container 1 being damaged is caused by the following reasons. From the perspective of quality management of the object, it is necessary to improve the airtightness of container 1. The higher the airtightness of container 1, the less air will leak from the gaps in container 1. As a result, the energy efficiency of the container refrigeration unit 10 can be improved. On the other hand, if the airtightness of container 1 is improved, when the interior of container 1 becomes negative pressure during cooling operation, it will be difficult for outside air to enter the interior of container 1 through the gaps. Therefore, the negative pressure inside container 1 will further increase with cooling operation, and this negative pressure will exceed the pressure resistance of container 1.

[0113] (7-2) Control of the pressure equalization mechanism

[0114] To solve the aforementioned technical problems, the container refrigeration unit 10 performs a pressure equalization operation. The pressure equalization operation is the action of achieving pressure equalization between the outside and inside of container 1 when the negative pressure inside container 1 rises during cooling operation. In other words, the pressure equalization operation is the action of introducing air from outside container 1 into container 1 when the negative pressure inside container 1 rises during cooling operation. In this embodiment, the pressure equalization operation is performed by the ventilation device 40, which serves as the pressure equalization mechanism. The pressure equalization operation includes a first pressure equalization operation and a second pressure equalization operation. The first pressure equalization operation is the action of achieving pressure equalization between the outside and inside of container 1 during the initial cooling operation. The second pressure equalization operation is the action of achieving pressure equalization between the outside and inside of container 1 after door D is opened and closed during cooling operation. The first pressure equalization operation is performed in a first mode. The first mode is the control mode that controls the pressure equalization mechanism during the initial cooling operation. The second pressure equalization operation is performed in a second mode. The second mode is the control mode that controls the pressure equalization mechanism after door D is opened and closed.

[0115] Reference Figures 7-9 The flowchart is used to explain in detail the control of the pressure equalization mechanism.

[0116] (7-2-1) Basic Control

[0117] like Figure 7 As shown, when a cooling operation start command is received in step S11, the control unit 100 starts the cooling operation in step S12. The cooling operation start command is input to the control unit 100 by the user operating the operation unit 110. It should be noted that when the cooling operation starts, the ventilation device 40 does not equalize the pressure inside and outside the container 1. Specifically, the opening / closing cover 45 of the ventilation device 40 is in the fully closed position.

[0118] The control unit 100 determines whether to perform a pressure equalization operation based on the pressure detected by the pressure sensor 53. The pressure detected by the pressure sensor 53 is equivalent to the pressure inside the container 1. The control unit 100 determines whether to switch to a first mode or a second mode based on the rate of change of the detected pressure before it drops below a first pressure. If the rate of change is slow, it switches to the first mode; if the rate of change is fast, it switches to the second mode.

[0119] Specifically, in step S13, when the first condition that the detected pressure of the pressure sensor 53 is below the first pressure is met and the time Δt until the detected pressure reaches the first pressure is greater than a predetermined time t1, the control unit 100 performs the first mode processing in step S17. The first pressure is a predetermined pressure lower than atmospheric pressure. The detected pressure is below the first pressure, in other words, the negative pressure is above a predetermined value. The first pressure is, for example, a pressure equivalent to a negative pressure of 2 [kPa]. The negative pressure equivalent to the first pressure is set to a predetermined value lower than the pressure resistance of container 1. The time Δt until the detected pressure reaches the first pressure is the period from the moment ta when the detected pressure begins to decrease to the moment tb when the detected pressure reaches the first pressure. The control unit 100, for example, sets the moment when the detected pressure begins to decrease at a predetermined rate of change (gradient) as moment ta.

[0120] Thus, in step S13, if the time Δt before the detected pressure reaches the first pressure is relatively long, it can be determined that the pressure inside container 1 has decreased due to the initial cooling operation. Therefore, the process transitions to the first mode in step S17, executing... Figure 8 The initial cooling operation shown corresponds to the control of the ventilation device 40.

[0121] If the condition in step S13 is not met, the process proceeds to step S14. In step S14, when the first condition of detecting pressure below the first pressure is met and the time Δt until the detected pressure reaches the first pressure is shorter than a predetermined time t1, the control unit 100 performs the second mode processing of step S18. When air is cooled inside container 1 as door D opens and closes during cooling operation, the rate of pressure drop inside container 1 is faster compared to the initial cooling operation. Therefore, when the time Δt until the detected pressure reaches the first pressure is relatively short, it can be determined that the pressure inside container 1 has decreased due to the opening and closing of door D. Thus, the process proceeds to the second mode of step S18 and execution... Figure 9 The control of the ventilation device 40 after the door D is opened or closed is shown.

[0122] If the conditions in steps S13 and S14 are not met, the process proceeds to step S15. In step S15, if there is a command to end the cooling operation, the control unit 100 ends the cooling operation in step S16. The command to end the cooling operation is input to the control unit 100 by the user operating the operation unit 110.

[0123] (7-2-2) First Mode

[0124] The first mode is the control mode for the ventilation device 40 during initial cooling operation. For example... Figure 8As shown, when switching to the first mode, in step S21, the control unit 100 controls the ventilation device 40 to perform a pressure equalization operation to equalize the pressure inside and outside the container 1. In other words, in the initial cooling operation (initial cooling operation) after the container refrigeration unit 10 is started, when the first condition in step S13 is met, the control unit 100 controls the ventilation device 40 to perform a first pressure equalization operation as a pressure equalization operation.

[0125] In step S21, the control unit 100 controls the ventilation device 40 to introduce a first flow rate of external air into the interior of the container 1. Specifically, the control unit 100 adjusts the rotation angle of the opening / closing cover 45 of the ventilation device 40, that is, adjusts the opening degree of the air supply passage 41 and the exhaust passage 42, so that the flow rate of the air introduced into the container 1 becomes the first flow rate. By introducing external air into the interior of the container 1, the pressure inside and outside the container 1 is made equalized. As a result, the pressure inside the container 1 rises rapidly. In other words, the negative pressure inside the container 1 decreases.

[0126] Next, in step S22, when the detected pressure is higher than the second pressure and the internal temperature is lower than the first temperature, the process proceeds to step S23. In step S23, the control unit 100 controls the ventilation device 40 to introduce outside air at a second flow rate into the interior of the container 1. The value of the second pressure is the same as the first pressure, which is equivalent to a negative pressure of 2 [kPa]. The second pressure can be higher or lower than the first pressure. The second flow rate is a specified flow rate smaller than the first flow rate. The first flow rate is, for example, 5 [m³ / s]. 3 / h], the second flow rate is, for example, 3 [m 3 / h]. The first temperature is, for example, 10°C. The internal temperature is the value detected by the internal temperature sensor 51.

[0127] Therefore, in this embodiment, during the pressure equalization operation, when the temperature of the air inside the container is lower than a specified temperature, the control unit 100 reduces the amount of air introduced into the container 1. This is because if the temperature of the air inside the container decreases, the pressure inside the container 1 will not drop significantly, thus reducing the risk of damage to the container 1. By reducing the amount of external air introduced, the air inside the container can be cooled rapidly during the initial cooling operation. By reducing the amount of external air introduced, the cooling load inside the container 1 can be reduced, thereby enabling the initial cooling operation to be completed quickly.

[0128] Next, in step S24, when the second condition (detection pressure higher than the second pressure) is met and the third condition (internal temperature below the second temperature) is met, the process proceeds to step S25. In step S25, the control unit 100 terminates the pressure equalization control of the ventilation device 40. Specifically, the control unit 100 keeps the opening / closing cover 45 of the ventilation device 40 fully closed. The second temperature is a predetermined temperature lower than the first temperature. The second temperature is, for example, 0°C.

[0129] If the temperature of the air inside the container reaches the second temperature (e.g., 0°C), even if the temperature of the air inside the container decreases further due to the initial cooling operation, the internal pressure of container 1 will not drop significantly, and the possibility of the interior of container 1 becoming negative pressure will also decrease. Therefore, in step S24, when the second and third conditions are met, the control unit 100 terminates the pressure equalization operation of the ventilation device 40.

[0130] Through the above controls, even when the pressure inside container 1 drops during initial cooling operation, the negative pressure inside container 1 can be prevented from exceeding the pressure resistance of container 1. As a result, damage to container 1 due to initial cooling operation can be prevented.

[0131] (7-2-3) Second Mode

[0132] The second mode is a control mode that controls the ventilation device 40 after the door D is temporarily opened or closed during cooling operation. As described above, when the heat exchanger 29 inside the chamber is in the temperature-controlled off state, in other words, when the temperature inside the chamber is within the target range, if the door D is temporarily opened or closed, the transition condition (step S14) of the second mode is easily met.

[0133] like Figure 9 As shown, when switching to the second mode, in step S31, the control unit 100 controls the ventilation device 40 to perform a pressure equalization operation to equalize the pressure inside and outside the container 1. In other words, when the door D is opened or closed during cooling operation, and the first condition in step S14 is met, the control unit 100 controls the ventilation device 40 to perform a second pressure equalization operation as a pressure equalization operation.

[0134] In step S31, the control unit 100 controls the ventilation device 40 to introduce a third flow rate of external air into the interior of the container 1. Specifically, the control unit 100 adjusts the rotation angle of the opening / closing cover 45 of the ventilation device 40, that is, adjusts the opening degree of the air supply passage 41 and the exhaust passage 42, so that the flow rate of the air introduced into the container 1 becomes the third flow rate. By introducing external air into the interior of the container 1, the pressure inside and outside the container 1 is made equalized. As a result, the pressure inside the container 1 rises rapidly. In other words, the negative pressure inside the container 1 decreases.

[0135] Here, the third flow rate is greater than the first and second flows rate of the first mode. The third flow rate is, for example, 10 [m]. 3 [ / h]. In other words, during the second pressure equalization operation, the ventilation device 40 introduces air from outside the container 1 into the interior of the container 1 at a flow rate greater than that during the first pressure equalization operation. As described above, after the door D is opened and closed, the pressure inside the container 1 drops faster compared to the initial cooling operation. In contrast, because the ventilation device 40 introduces outside air at a larger flow rate, it is able to prevent the negative pressure inside the container 1 from reaching the pressure resistance of the container 1.

[0136] Next, in step S32, when the second condition of the detected pressure being higher than the second pressure is met, the process proceeds to step S33. In step S33, the control unit 100 terminates the pressure equalization control of the ventilation device 40. Specifically, the control unit 100 keeps the opening / closing cover 45 of the ventilation device 40 in the fully closed position.

[0137] Through the above controls, even if the pressure inside container 1 decreases with the opening and closing of door D, the negative pressure inside container 1 can be prevented from exceeding the pressure resistance of container 1. As a result, damage to container 1 due to the opening and closing of door D can be prevented.

[0138] (8) Effects of the implementation method

[0139] (8-1)

[0140] During the cooling operation that cools the interior of container 1, when the first condition is met—that the pressure detected by the pressure detection unit P is lower than a predetermined first pressure less than atmospheric pressure—the control unit 100 of this embodiment controls the ventilation device 40 to perform a pressure equalization operation that equalizes the pressure inside and outside of container 1.

[0141] Therefore, even if the pressure inside container 1 decreases due to the cooling of the air inside, the pressure inside container 1 can be rapidly increased through pressure equalization. As a result, the increase of negative pressure inside container 1 can be suppressed, thereby preventing damage to container 1.

[0142] Furthermore, by implementing such controls, damage to the container 1 can be prevented even when using a highly airtight container 1. As a result, the energy efficiency of the container refrigeration unit 10 can be prevented from being compromised due to the entry of outside air through gaps in the container 1.

[0143] (8-2)

[0144] In this embodiment, the pressure equalization mechanism is a ventilation device 40 that ventilates the container 1. Therefore, the ventilation device 40 can be used as a pressure equalization mechanism, thus reducing the number of components. The ventilation device 40 can introduce a relatively large flow of outside air into the container 1. Therefore, even in the event of a sharp drop in pressure inside the container 1, sufficient outside air to handle the situation can be quickly introduced into the container 1.

[0145] Furthermore, the ventilation device 40 can adjust the ventilation volume, i.e., the amount of outside air introduced. Therefore, it is possible to introduce outside air into the container 1 in accordance with the degree of pressure drop inside the container 1. As a result, it is possible to prevent the energy efficiency of the container refrigeration unit 10 from being compromised due to the introduction of excessive outside air.

[0146] (8-3)

[0147] During the pressure equalization operation, when the pressure detected by the pressure detection unit P is higher than a predetermined second pressure that is lower than atmospheric pressure, the control unit 100 terminates the pressure equalization operation.

[0148] Therefore, it is possible to avoid continuing the pressure equalization operation when the pressure inside container 1 is high. As a result, it is possible to prevent the energy efficiency of the container refrigeration unit 10 from being compromised due to the introduction of excessive outside air.

[0149] (8-4)

[0150] When the pressure detected by the pressure detection unit P is higher than a predetermined second pressure lower than atmospheric pressure, and the temperature of the air inside container 1 is lower than a predetermined temperature, the control unit 100 terminates the pressure equalization operation. In other words, even if the pressure detected by the pressure detection unit P is higher than a predetermined second pressure lower than atmospheric pressure, the control unit 100 does not terminate the pressure equalization operation when the temperature of the air inside container 1 is above a predetermined temperature.

[0151] If the air temperature inside container 1 is relatively low (e.g., 0°C), the risk of a rise in negative pressure inside container 1 due to further cooling of the air is low. Therefore, it is possible to prevent the negative pressure inside container 1 from rising again after the pressure equalization process has ended, which could lead to damage to container 1.

[0152] (8-5)

[0153] During the initial cooling operation (initial cooling operation) after the container refrigeration unit 10 is started, when the pressure detected by the pressure detection unit P is lower than a specified first pressure less than atmospheric pressure, the control unit 100 controls the ventilation device 40 to perform a first pressure equalization operation as a pressure equalization operation.

[0154] During the initial cooling operation, the negative pressure inside container 1 is prone to rise, increasing the risk of container 1 breaking. By performing the first pressure equalization action at this moment, damage to container 1 can be avoided.

[0155] (8-6)

[0156] During cooling operation, after the door D of container 1 is opened or closed, when the pressure detected by the pressure detection unit P is lower than the specified first pressure which is less than atmospheric pressure, the control unit 100 controls the ventilation device 40 to perform a second pressure equalization operation as a pressure equalization operation.

[0157] If the door of container 1 is temporarily opened or closed, the negative pressure inside container 1 is likely to rise, increasing the risk of container 1 breaking. By performing a second pressure equalization action at that moment, damage to container 1 can be avoided.

[0158] (8-7)

[0159] During cooling operation (strictly speaking, initial cooling operation), the control unit 100 controls the pressure equalization mechanisms 40 and 80 so that the flow rate of air introduced from the outside of container 1 to the inside decreases as the temperature of the air inside the container decreases.

[0160] When the temperature of the air inside the container is high, the negative pressure of container 1 can easily rise due to the cooling of the air inside the container. At this time, because the amount of outside air introduced increases, damage to container 1 can be reliably prevented.

[0161] When the temperature of the air inside the container is low, the negative pressure of container 1 is unlikely to rise due to cooling of the air inside the container. At this time, because the amount of outside air introduced is reduced, the amount of outside air introduced will not become excessive. As a result, it is possible to suppress any impairment of the reliability of the container refrigeration unit 10 due to the introduction of outside air. In particular, when the temperature of the air inside the container is low, the temperature difference between the outside air and the inside air is large, and the cooling load of container 1 is easily increased by the introduction of outside air. At this time, by reducing the amount of outside air introduced, it is possible to avoid compromising the energy efficiency of the container refrigeration unit 10.

[0162] (8-8)

[0163] The pressure detection unit P is a pressure sensor 53. Therefore, it can accurately detect the pressure inside container 1.

[0164] (9) Variations

[0165] The above-described embodiments can also employ the structures of the variations described below. Hereinafter, the differences from the above-described embodiments will be specifically explained.

[0166] (9-1) Modification Example 1: Modification of the pressure detection unit

[0167] The pressure detection unit P in the above embodiment can also adopt the structure of the modified example described below.

[0168] (9-1-1) Variation 1A

[0169] like Figure 10 As schematically shown, the container refrigeration unit 10 of Modification 1A includes a drain pipe 60. The inlet end 60a of the drain pipe 60 communicates with the interior space 3 inside the container 1. The outlet end 60b of the drain pipe 60 communicates with the exterior space 5 outside the container 1. The inlet end 60a of the drain pipe 60 forms a flow path for draining water received by a drain pan inside the container 1 to the exterior of the container 1. The drain pan is arranged below the heat exchanger 29 inside the container to receive condensate generated from the air cooled in the heat exchanger 29. The drain pipe 60 can be a flexible resin hose or a rigid metal pipe.

[0170] The drain pipe 60 has a downward-curving trap 61. The trap 61 includes: a first straight pipe section 62 near the interior of the container 1; a second straight pipe section 63 near the exterior of the container 1; and a U-shaped U-shaped section 64 connected to the lower ends of the first and second straight pipe sections 62 and 63. The first and second straight pipe sections 62 and 63 extend vertically. The cross-sectional area of ​​the flow path of the first straight pipe section 62 is equal to that of the second straight pipe section 63. Water accumulates in the trap 61, thereby separating the interior and exterior of the container 1.

[0171] Modification 1A's pressure detection unit P includes a level gauge for measuring the water level in the trap 61 and a control unit 100. The level gauge includes a first level sensor 65 and a second level sensor 66. The first and second level sensors 65 and 66 are ultrasonic, radio wave, electrode, or float-type level sensors, etc. The first level sensor 65 is disposed inside the first straight pipe section 62. The first level sensor 65 measures the water level inside the first straight pipe section 62. The second level sensor 66 is disposed inside the second straight pipe section 63. The second level sensor 66 measures the water level inside the second straight pipe section 63.

[0172] The pressure detection unit P detects pressure based on the water level difference between the first straight pipe section 62 and the second straight pipe section 63. When the pressure Pb inside container 1 is equal to the pressure P0 (atmospheric pressure) outside container 1, such as... Figure 10 As shown, the water level h1 in the first straight pipe section 62 is equal to the water level h2 in the second straight pipe section 63. In contrast, if the pressure Pb inside the container 1 decreases during cooling operation, this pressure Pb will be less than the pressure P0 outside the container 1. As a result, as... Figure 11As shown, the water level h1 in the first straight pipe section 62 will be higher than the water level h2 in the second straight pipe section 63. Figure 11 Under the condition that, the following relation (1) holds.

[0173] Pb×A1+ρ×g×H×A1=P0×A2 (1)

[0174] Here, A1 is the flow path cross-sectional area of ​​the first straight pipe section 62, and A2 is the flow path cross-sectional area of ​​the second straight pipe section 63. In this example, A1 and A2 are equal. ρ is the density of water, g is the acceleration due to gravity, and H is the difference between water level h1 and water level h2 (H = h1 - h2).

[0175] The control unit 100 uses the water levels measured by the first water level sensor 65 and the second water level sensor 66, along with the relationship (1), to calculate the pressure inside the container 1. Based on the above, in Modification 1, the pressure inside the container 1 can be detected.

[0176] (9-1-2) Variation 1B

[0177] In Modification 1B, the pressure detection unit P detects the pressure inside container 1 based on the temperature of the air inside container 1 and the temperature of the air inside container 1 during cooling operation. The pressure detection unit P includes an internal temperature sensor 51 and a control unit 100.

[0178] The container temperature sensor 51 measures the air temperature T0 inside the container 1 before or at the start of cooling operation. Then, during cooling operation, the container temperature sensor 51 measures the air temperature Tb inside the container 1. The control unit 100 calculates the pressure Pb inside the container 1 according to the following relationship (2) based on Boyle's law.

[0179] P0×V / T0=Pb×V / Tb (2)

[0180] Here, P0 is the pressure inside container 1 before or at the start of cooling operation, equivalent to atmospheric pressure. V is the volume of the internal space 3 inside container 1. Based on the above, in modified example 2, the pressure inside container 1 can be detected.

[0181] The pressure detection unit P may also include an external temperature sensor 52. The temperature measured by the external temperature sensor 52 may also be used as the temperature T0 of the air inside container 1 before or at the start of cooling operation.

[0182] (9-1-3) Variation 1C

[0183] like Figure 12As shown, the pressure detection unit P in Modified Example 1C includes a humidity sensor 71 (which functions as a gas sensor) and a control unit 100. The humidity sensor 71 measures the concentration of water vapor in the air inside the container 1, i.e., the humidity of the air. The humidity sensor 71 is located inside the container 1. The humidity sensor 71 is positioned upstream of the container fan 30 in the airflow direction within the internal passageway 19. The humidity sensor 71 is a capacitive or resistive sensor. The humidity sensor 71 has the characteristic that its detected value changes according to the pressure around it.

[0184] Humidity sensor 71 measures the humidity R0 of the air inside container 1 before or at the start of cooling operation. Subsequently, humidity sensor 71 measures the humidity Rb of the air inside container 1 during cooling operation. The humidity measured by humidity sensor 71 varies according to the pressure inside container 1. In other words, the humidity detected by humidity sensor 71 is correlated with the pressure inside container 1. Control unit 100 stores data related to the humidity detected by humidity sensor 71 and the pressure inside container 1. This data is a relational expression or a table. Control unit 100 uses this data, humidity R0, and humidity Rb to calculate the pressure inside container 1. Based on the above description, in modified example 1C, the pressure inside container 1 can be detected using humidity sensor 71.

[0185] The humidity sensor 71 is also used to regulate the humidity of the air inside container 1. The control unit 100 controls the refrigerant circuit R based on the detection value of the humidity sensor 71.

[0186] (9-1-4) Variation 1D

[0187] like Figure 13 As shown, the pressure detection unit P of Modified Example 1D includes a carbon dioxide sensor 72 as a gas sensor and a control unit 100. The carbon dioxide sensor 72 measures the concentration of carbon dioxide in the air inside the container 1. The carbon dioxide sensor 72 is arranged inside the container 1. The carbon dioxide sensor 72 is positioned upstream of the container fan 30 in the airflow direction within the internal passageway 19. The carbon dioxide sensor 72 is a semiconductor, infrared (NDIR), or thermal conductivity sensor. The carbon dioxide sensor 72 has the characteristic that its detected value changes according to the pressure around it.

[0188] The carbon dioxide sensor 72 measures the carbon dioxide concentration C0 in the air inside container 1 before or at the start of cooling operation. Subsequently, the carbon dioxide sensor 72 measures the carbon dioxide concentration Cb in the air inside container 1 during cooling operation. The carbon dioxide concentration measured by the carbon dioxide sensor 72 varies according to the pressure inside container 1. In other words, the concentration detected by the carbon dioxide sensor 72 is correlated with the pressure inside container 1. The control unit 100 stores data related to the concentration detected by the carbon dioxide sensor 72 and the pressure inside container 1. This data is a formula or a table. The control unit 100 uses this data, concentration C0, and concentration Cb to calculate the pressure inside container 1. Based on the above description, in Modification 1D, the pressure inside container 1 can be detected using the carbon dioxide sensor 72. Alternatively, the gas sensor may not be the carbon dioxide sensor 72, but rather an oxygen sensor that measures the oxygen concentration in the air inside container 1.

[0189] Carbon dioxide sensor 72 and oxygen sensor are used to regulate the air composition inside container 1. Control unit 100 controls regulating device 80 based on the concentrations detected by carbon dioxide sensor 72 and oxygen sensor 72. Regulating device 80 uses, for example, a PSA (Pressure Swing Adsorption) device or a gas separation membrane to regulate the air composition in the container space 3. Details of regulating device 80 will be described later.

[0190] The control unit 100 can also adjust the ventilation rate of the ventilation device 40 based on the detected concentrations of the carbon dioxide sensor 72 and the oxygen sensor.

[0191] (9-2) Variation Example 2: Variation of the pressure equalization mechanism

[0192] The pressure equalization mechanisms 40 and 80 in the above embodiments can also adopt the structure of the modified examples described below.

[0193] (9-2-1) Variation Example 2A

[0194] like Figure 14 As schematically shown, the pressure equalization mechanism of Modification 2A is a regulating device 80 that regulates the air composition inside the container 1. The regulating device 80 is arranged in the external storage space 14 of the shell 11. The regulating device 80 has a supply passage 81, an exhaust passage 82, an air pump 83, and a PSA device 84.

[0195] Supply path 81 is a flow path for introducing outside air into the internal space 3 of the chamber. The inlet end of supply path 81 opens into the external space 5. The outlet end of supply path 81 communicates with the internal space 3 of the chamber. Exhaust path 82 is a flow path for discharging air from the PSA unit 84 into the external space 5 of the chamber.

[0196] An air pump 83 and a PSA device 84 are provided in the supply line 81. The air pump 83 is a delivery section for supplying air. It also serves as a pressurization section for pressurizing the air and a depressurization section for depressurizing the air. The PSA device 84 has two adsorption sections. Each adsorption section is an adsorption tower filled with an adsorbent that adsorbs nitrogen from the air. The adsorbent may be, for example, zeolite.

[0197] Air pump 83 pressurizes one of the two adsorption sections and depressurizes the other. In the pressurized adsorption section, nitrogen in the air is adsorbed by the adsorbent, thereby generating oxygen-rich air with a lower nitrogen concentration and a higher oxygen concentration than the outside air. In the depressurized adsorption section, nitrogen is released from the adsorbent, thereby generating nitrogen-rich air with a higher nitrogen concentration and a lower oxygen concentration than the outside air. The oxygen-rich air is discharged to the external space 5 through exhaust passage 82. The nitrogen-rich air is supplied to the internal space 3 through supply passage 81. Thus, the oxygen concentration in the internal space 3 is regulated.

[0198] In Modification 2A, when the pressure inside container 1 falls below a first pressure during cooling operation, control unit 100 controls regulating device 80 to equalize the pressure inside and outside container 1. Specifically, control unit 100 operates air pump 83 to perform an equalization operation, introducing air from outside container 1 into the interior of container 1 through supply path 81. This helps to prevent damage to container 1 caused by negative pressure.

[0199] Preferably, the regulating device 80 has a bypass flow path that, during pressure equalization operation, allows air in the supply path 81 to bypass the PSA device 84 and be supplied to the interior space 3. This allows external air to be introduced into the interior of the container 1 with its original composition. Furthermore, it reduces the flow resistance of the air flowing in the supply path 81, thereby reducing the power consumption of the air pump 83.

[0200] The regulating device 80 can also introduce air that has been pressurized to above atmospheric pressure by the air pump 83 during the pressure equalization operation. This allows the pressure inside container 1 to rise rapidly.

[0201] When the pressure inside container 1 becomes higher than the second pressure due to the pressure equalization operation, the control unit 100 terminates the pressure equalization operation of the regulating device 80. Specifically, the control unit 100 stops the air pump 83.

[0202] In Modification 2B, the regulating device 80 not only regulates the composition of the air, but also functions as a pressure equalization mechanism, thus reducing the number of parts.

[0203] (9-2-2) Variation Example 2B

[0204] Modification 2B takes a refrigerated container C, including a refrigeration unit 10 and a container 1, as an example. The pressure equalization mechanism in Modification 2B is the door D of container 1. For example... Figure 15 As shown, the refrigerated container 1 has a drive mechanism 90 that automatically opens and closes the door D. The drive mechanism 90 opens and closes the door D according to the instructions of the control unit 100.

[0205] If the pressure inside container 1 falls below the first pressure during cooling operation, the control unit 100 controls the drive mechanism 90 to open the door D, thereby equalizing the pressure inside and outside container 1. This allows the pressure inside container 1 to rise rapidly, thus preventing damage to container 1 caused by negative pressure.

[0206] When the pressure inside container 1 becomes higher than the second pressure due to the pressure equalization action, the control unit 100 terminates the pressure equalization action of the regulating device 80. Specifically, the control unit 100 controls the drive mechanism 90 to close the door D.

[0207] (9-3) Variation Example 3

[0208] The control unit 100 can also execute the following when the first condition is met: the cooling operation is the initial cooling operation and the detection pressure is below the first pressure. Figure 8 The control unit 100 is shown in the first mode of control. When it receives the start command for the initial cooling operation after the power is turned on for the container refrigeration unit 10, the control unit 100 determines the cooling operation as the initial cooling operation.

[0209] (9-4) Variation Example 4

[0210] The container refrigeration unit 10 may also include a detection unit that detects whether door D is opened or closed. Specifically, when the detection unit detects that a fourth condition—that door D has been opened or closed—is met during cooling operation, and a first condition—that the detection pressure is below a first pressure—is met, the control unit 100 executes... Figure 9 The second mode of control is shown.

[0211] Alternatively, the control unit 100 may execute the second mode of control when the temperature of the air inside the chamber rises above the target range (fifth condition is met) and the first condition is met. The control unit 100 may also execute the second mode of control when the fourth, fifth, and first conditions are met sequentially.

[0212] (9-5) Variation Example 5

[0213] Alternatively, the first pressure (refer to step S14) used as the determination value for executing the second pressure equalization action in the second mode can be higher than the first pressure (refer to step S13) used as the determination value for executing the first pressure equalization action in the first mode. In this case, when the pressure inside container 1 decreases due to opening and closing door D during cooling operation, the second pressure equalization action in the second mode can be executed quickly. As described above, although the pressure inside container 1 drops sharply after door D is opened and closed, damage to container 1 can be suppressed by quickly responding to this pressure change.

[0214] (9-6) Variation Example 6

[0215] The control unit 100 can also control the pressure equalization mechanisms 40 and 80 during cooling operation to reduce the flow rate of air introduced from the outside of the container 1 to the inside as the cooling operation time progresses. Preferably, the control unit 100 controls the pressure equalization mechanisms 40 and 80, especially during the initial cooling operation, to reduce the flow rate of air introduced from the outside of the container 1 to the inside as the cooling operation time progresses.

[0216] The temperature of the air inside the container decreases over time as the cooling operation continues. When the air temperature inside the container is low, the negative pressure in container 1 is unlikely to rise due to cooling. At this time, because the amount of external air introduced is reduced, the amount of external air introduced will not become excessive. As a result, the reliability of the container refrigeration unit 10 can be prevented from being compromised due to the introduction of external air. When the air temperature inside the container is low, the cooling load of container 1 is prone to increase due to the introduction of external air. At this time, by reducing the amount of external air introduced, the energy efficiency of the container refrigeration unit 10 can be avoided.

[0217] (9-7) Variation Example 7

[0218] In Modification 7, the control unit 100 controls the refrigerant circuit R to perform a dehumidification operation to dehumidify the air inside the container before cooling operation. During dehumidification operation, the compressor 25 operates, and the internal heat exchanger 29 functions as an evaporator. The control unit 100 adjusts the speed of the compressor 25, thereby adjusting the evaporation temperature of the internal heat exchanger 29 so that the temperature of the air cooled in the internal heat exchanger 29 reaches below the dew point temperature. The evaporation temperature Te1 during dehumidification operation is higher than the evaporation temperature Te2 during cooling operation. Therefore, during dehumidification operation, the air can be dehumidified without causing a significant drop in the temperature of the air inside the container 1.

[0219] If cooling is performed after dehumidification, the temperature of the air inside container 1 will decrease as described above. Here, the humidity of the air inside the container is reduced by the dehumidification operation. Therefore, even though the air inside container 1 is cooled, a significant drop in pressure inside container 1 can be prevented. As a result, damage to container 1 due to negative pressure can be prevented.

[0220] (10) Other implementation methods

[0221] In the above embodiments and variations, the following structures may also be adopted.

[0222] Container 1 can also be used for land transport, which can be carried by vehicles such as trailers or railways, instead of by sea.

[0223] The ventilation device 40 may only have the function of supplying air from outside the container space 5 to inside the container space 3, without having an exhaust function. In other words, the ventilation device 40 may only have an air supply passage 41, while exhaust is carried out naturally through an exhaust port provided on the container body 2.

[0224] The ventilation fan of the ventilation device 40 can also be a special ventilation fan that is different from the fan inside the box.

[0225] The opening adjustment mechanism for regulating the opening of the air supply passage 41 and the exhaust passage 42 does not necessarily have to be an opening and closing cover 45. The opening adjustment mechanism can also be a damper or valve mechanism installed in the air supply passage 41 and the exhaust passage 42.

[0226] The above describes the implementation methods and variations, but it is understood that various changes can be made to the scheme and specific circumstances without departing from the spirit and scope of the claims. Furthermore, appropriate combinations or substitutions can be made to the above implementation methods, variations, and other implementation methods as long as the function of the object of this disclosure is not impaired.

[0227] The terms "first," "second," "third," etc., mentioned above are only used to distinguish statements containing these terms and are not intended to limit the number or order of the statements.

[0228] -Industry Applicability-

[0229] In summary, this disclosure is useful for refrigeration equipment for containers.

[0230] - Symbol Explanation -

[0231] 1 container

[0232] 10 Refrigeration units for containers

[0233] 40. Ventilation device (pressure equalization mechanism)

[0234] 53 Pressure Sensor

[0235] 60 Drainage pipes

[0236] 61 Water trap

[0237] 71, 72 Gas Sensors

[0238] 80. Regulating device (pressure equalization mechanism)

[0239] 100 Control Department

[0240] D door

[0241] P Pressure Testing Department

Claims

1. A refrigeration unit for a container, characterized by: The container refrigerating apparatus includes a pressure detecting portion (P) that detects a pressure inside a container (1), The pressure equalizing mechanism (40, 80) equalizes the pressure inside the container (1) with the outside, In cooling operation in which the inside of the container (1) is cooled, when the pressure detected by the pressure detecting portion (P) is lower than a prescribed first pressure that is lower than atmospheric pressure, the control portion (100) controls the pressure equalizing mechanism (40, 80) to perform pressure equalizing operation in which the inside of the container (1) is equalized with the outside.

2. The reefer unit for a container according to claim 1, characterized by: The pressure equalizing mechanism (40, 80) is a ventilation device (40) that ventilates the container (1), The ventilation device (40) introduces air from the outside of the container (1) into the inside of the container (1) in the pressure equalizing operation.

3. The refrigeration unit for containers according to claim 1, characterized in that: The pressure equalizing mechanism (40, 80) is a regulating device (80) that regulates the composition of air inside the container (1), The regulating device (80) introduces air from the outside of the container (1) into the inside of the container (1) in the pressure equalizing operation.

4. A reefer unit for a container according to any one of claims 1 to 3, characterized in that: In the pressure equalizing operation, when the pressure detected by the pressure detecting portion (P) is higher than a prescribed second pressure that is lower than atmospheric pressure, the control portion (100) ends the pressure equalizing operation.

5. The reefer container unit according to claim 4, characterized in that: When the pressure detected by the pressure detecting portion (P) is higher than a prescribed second pressure that is lower than atmospheric pressure and the temperature of air inside the container (1) is lower than a prescribed temperature, the control portion (100) ends the pressure equalizing operation.

6. The refrigeration device for a container according to any one of claims 1 to 5, characterized in that: In initial cooling operation after the container refrigerating apparatus is started, when the pressure detected by the pressure detecting portion (P) is lower than a prescribed first pressure that is lower than atmospheric pressure, the control portion (100) controls the pressure equalizing mechanism (40, 80) to perform first pressure equalizing operation as the pressure equalizing operation.

7. A reefer unit for a container according to any one of claims 1 to 5, characterized in that: After a door of the container (1) is opened and closed in cooling operation, when the pressure detected by the pressure detecting portion (P) is lower than a prescribed first pressure that is lower than atmospheric pressure, the control portion (100) controls the pressure equalizing mechanism (40, 80) to perform second pressure equalizing operation as the pressure equalizing operation.

8. A reefer unit for a container as claimed in claim 7, characterized in that: In initial cooling operation after the container refrigerating apparatus is started, when the pressure detected by the pressure detecting portion (P) is lower than a prescribed first pressure that is lower than atmospheric pressure, the control portion (100) controls the pressure equalizing mechanism (40, 80) to perform first pressure equalizing operation as the pressure equalizing operation, The pressure equalizing mechanism (40, 80) introduces air from the outside of the container (1) into the inside of the container (1) in the second pressure equalizing operation at a flow rate greater than in the first pressure equalizing operation.

9. A reefer unit for a container according to any one of claims 1 to 8, characterized in that: The control portion (100) controls the pressure equalizing mechanism (40, 80) in cooling operation so that the flow rate of air introduced from the outside into the inside of the container (1) decreases as the temperature of air inside the container (1) decreases.

10. A reefer unit for a container according to any one of claims 1 to 9, characterized in that: The pressure detecting portion (P) is a pressure sensor (53).

11. The refrigeration device for a container according to any one of claims 1 to 9, characterized in that: The container refrigerating apparatus includes a drain pipe (60) that discharges condensate generated inside the container (1) to the outside of the container (1) and has a trap (61) that stores the condensate, The pressure detecting portion (P) detects the pressure inside the container (1) in accordance with the water level of the trap (61).

12. A reefer unit for a container according to any one of claims 1 to 9, characterized in that: The pressure detecting portion (P) detects the pressure inside the container (1) in accordance with the temperature of the air inside the container (1) before or at the start of the cooling operation and the temperature of the air inside the container (1) during the cooling operation.

13. A reefer unit for a container as claimed in any one of claims 1 to 9, characterized in that: The container refrigerating apparatus includes a gas sensor (71, 72) that detects the concentration of a gas component in the air inside the container (1), The pressure detecting portion (P) detects the pressure inside the container (1) in accordance with the detected concentration of the gas sensor (71, 72) before or at the start of the cooling operation and the detected concentration of the gas sensor (71, 72) during the cooling operation.

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