Air composition adjustment device, refrigeration device for transportation, and container for transportation

Abstract

A controller (110) executes flow rate control for at least adjusting the flow rate of first air so that the concentration of components in indoor air reaches a set value during operation of air conveyance units (231, 291).

Description

Air composition adjustment device, refrigeration device for transportation, and transportation container

[0001] The present disclosure relates to an air composition adjustment device, a refrigeration device for transportation, and a transportation container.

[0002] There is an air composition adjustment device that adjusts the composition of air in a storage such as a container. The air composition adjustment device of Patent Document 1 adjusts the composition of outdoor air, specifically, the oxygen concentration and carbon dioxide concentration, by an adsorption cylinder that is an air treatment unit. The treated gas whose composition has been adjusted by the air treatment unit is supplied to the space inside the storage.

[0003] This air composition adjustment device executes an oxygen concentration 5% mode, an oxygen concentration 8% mode, an outside air introduction mode, and a breathing mode. The oxygen concentration 5% mode and the oxygen concentration 8% mode are modes in which the treated gas adjusted to a low oxygen concentration by the air treatment unit is supplied to the space inside the storage. The outside air introduction mode is a mode in which outside air is supplied to the space inside the storage. The breathing mode is a mode in which the air pump is stopped, and the oxygen concentration of the air inside the storage is decreased and the carbon dioxide concentration is increased by the respiration of goods (fresh fruits and flowers).

[0004] Japanese Unexamined Patent Application Publication No. 2023 - 58951

[0005] In the air composition adjustment device, the composition of the air inside the storage is made to approach the set value by switching between the above-described plurality of modes. However, by switching each mode, the composition of the space inside the storage, specifically, the oxygen concentration and carbon dioxide concentration, changes greatly. As a result, the quality of fresh fruits and flowers may be impaired.

[0006] An object of the present disclosure is to provide an air composition adjustment device that can reduce the range of change in the composition of the air inside the storage.

[0007] The first embodiment relates to an air composition adjustment device. The air composition adjustment device includes a supply passage (S) that connects the space outside the storage compartment (6) and the space inside the storage compartment (5) inside the storage compartment (2), an air processing unit (95) provided in the supply passage (S) that adjusts the composition of the air, an air conveying unit (231, 291) that conveys the processed gas whose composition has been adjusted by the air processing unit (95) to the space inside the storage compartment (5) as first air via the supply passage (S), and a controller (110) that controls the air processing unit (95) and the air conveying unit (231, 291). The controller (110) performs flow rate control during the operation of the air conveying unit (231, 291) to adjust the flow rate of the first air to at least a set value so that the concentration of components in the air inside the storage compartment reaches a set value.

[0008] In the first embodiment, when the air conveying unit (231, 291) is in operation, the controller (110) adjusts the flow rate of the first air processed by the air processing unit (95) so that the concentration of the components in the air inside the chamber becomes a set value. If the flow rate of the first air changes, the supply rate of the components supplied to the space inside the chamber changes, so that the concentration of the components in the air inside the chamber can be brought closer to the set value. Therefore, it is possible to suppress changes in the composition of the air inside the chamber that occur when switching modes.

[0009] In the second embodiment, in the first embodiment, the controller (110) performs a concentration control mode in which it supplies first air from the supply path (S) to the storage space (5) in response to an operation command. The controller (110) performs flow rate control during the concentration control mode. The controller (110) performs flow rate control during the concentration control mode.

[0010] In the second embodiment, in one concentration adjustment mode, the concentration of components in the internal air is adjusted to a set value by flow rate control. Therefore, it is possible to suppress large changes in the composition of the internal air that occur when switching modes.

[0011] In a third embodiment, in the first or second embodiment, the air transport unit includes a variable flow rate pump (231, 291). The controller (110) adjusts the flow rate of the first air by controlling the pump (231, 291) in flow rate control.

[0012] In the third embodiment, the flow rate of the first air is adjusted by controlling the pumps (231, 291), and the concentration of the components in the air inside the chamber becomes a set value.

[0013] A fourth embodiment further comprises an outside air introduction unit (40) that, in the first or second embodiment, introduces outside air from the outside space (6) into the inside space (5) as second air without going through the supply path (S). In flow rate control, the controller (110) adjusts the flow rate of the first air and the flow rate of the second air so that the concentration of components in the inside air reaches a set value.

[0014] In the fourth embodiment, in addition to the flow rate of the first air, the flow rate of the second air supplied to the interior space (5) by the outside air inlet (40) is controlled so that the concentration of components in the interior air reaches a set value.

[0015] A fifth embodiment is the fourth embodiment, wherein the outside air intake (40) includes a ventilation device (40) that supplies outside air into the interior space (5).

[0016] In the fifth embodiment, in addition to the flow rate of the first air, the flow rate of the second air supplied to the interior space (5) by the ventilation device (40) is controlled so that the concentration of the components in the interior air reaches a set value.

[0017] The sixth embodiment is one of the first to fifth embodiments, in which the controller (110) performs concentration control to adjust the concentration of the components of the first air so that the concentration of the components in the air inside the chamber reaches a set value while the air conveying unit (231, 291) is in operation.

[0018] In the sixth embodiment, when the air conveying unit (231, 291) is in operation, the controller (110) adjusts the concentration of the components in the first air processed by the air processing unit (95) so that the concentration of the components in the air inside the chamber becomes a set value. If the concentration of the components in the first air changes, the supply rate of the components supplied to the space inside the chamber changes, so that the concentration of the components in the air inside the chamber can be brought closer to the set value. Therefore, it is possible to suppress large changes in the composition of the air inside the chamber that occur when switching modes.

[0019] The seventh aspect is the sixth aspect, wherein the air processing unit (95) includes two adsorption units (234, 235) that perform an adsorption operation to adsorb components in the air and a desorption operation to desorb the adsorbed components. The air composition adjustment device further includes a first flow path (244, 275) through which a processed gas whose composition has been adjusted by the adsorption units (234, 235) flows, a second flow path (281) for discharging the processed gas from the first flow path (244, 275) to the outside of the chamber, and an on-off valve (272) provided in the second flow path (281). The controller (110) adjusts the concentration of the components of the first air by controlling the timing of opening and closing the on-off valve (272) in concentration control.

[0020] In the seventh embodiment, the concentration of the components in the first air is adjusted by controlling the timing of opening and closing the on-off valve (272). This is because the concentration of the components in the processed gas flowing from the adsorption section (234, 235) to the first flow path (244, 275) changes, for example, during the desorption operation. If the on-off valve (272) is opened at a time when the concentration of the components in the processed gas is high, the high-concentration processed gas is discharged into the space outside the chamber (6). As a result, the concentration of the components in the first air supplied to the space inside the chamber (5) can be adjusted to be low. If the on-off valve (272) is opened at a time when the concentration of the components in the processed gas is low, the low-concentration processed gas is discharged into the space outside the chamber (6). As a result, the concentration of the components in the first air supplied to the space inside the chamber (5) can be adjusted to be high.

[0021] The eighth aspect is the sixth aspect, wherein the air processing unit (95) includes two adsorption units (234, 235) that perform an adsorption operation to adsorb components in the air and a desorption operation to desorb the adsorbed components. The air processing unit further includes a first flow path (244, 275) through which a processed gas whose composition has been adjusted by the adsorption units (234, 235) flows, a third flow path (255) that introduces outside air from the outside space (6) into the first flow path (244, 275) by bypassing the air processing unit (95), and a flow control valve (256) that adjusts the flow rate of outside air flowing from the third flow path (255) into the first flow path (244, 275). In concentration control, the controller (110) adjusts the concentration of the components of the first air by controlling the flow control valve (256).

[0022] In the eighth embodiment, by opening the flow control valve (256) to a predetermined opening, the processed gas whose composition has been adjusted in the air processing unit (95) and the outside air flowing through the second flow path (281) bypassing the air processing unit (95) are mixed in the first flow path (244, 275). By adjusting the opening of the flow control valve (256), the mixing ratio of the two gases changes, and thus the concentration of the components of the first air can be adjusted.

[0023] In the ninth aspect, in any one of the first to eighth aspects, the controller (110) determines a target flow rate to bring the carbon dioxide concentration in the air inside the chamber to a set value. In flow rate control, the controller (110) adjusts the flow rate of the first air to the target flow rate.

[0024] In the ninth embodiment, the carbon dioxide concentration in the air inside the chamber is brought to a set value by adjusting the flow rate of the first air to a target flow rate. Here, since the carbon dioxide concentration in the first air is relatively low, the target flow rate can be determined by ignoring the carbon dioxide concentration contained in the first air.

[0025] In the tenth aspect, as in the ninth aspect, the controller (110) estimates the carbon dioxide generation rate of fruits, vegetables or flowers in the storage space (5). The controller (110) determines the target flow rate based on the estimated carbon dioxide generation rate.

[0026] In the tenth embodiment, the target flow rate required for the carbon dioxide concentration in the warehouse air to reach a set value is determined based on the carbon dioxide generation rate of fruits, vegetables, or flowers. This is because the carbon dioxide concentration in the warehouse air is affected by the carbon dioxide generation rate of the cargo. This allows the carbon dioxide concentration in the warehouse air to quickly approach the set value.

[0027] In the eleventh aspect, in the tenth aspect, the controller (110) estimates the carbon dioxide generation rate based on the actual volume of the interior space (5) and the carbon dioxide concentration in the interior air. Here, "actual volume" means the actual volume of the interior space, or in other words, the actual volume of the interior air present in the interior space.

[0028] In the eleventh embodiment, the carbon dioxide generation rate of fruits, vegetables, or flowers is estimated based on the actual volume (Vs) of the storage space (5) and the carbon dioxide concentration in the storage space air. The carbon dioxide concentration in the storage space air is affected by the actual volume of the storage space (5) and the carbon dioxide generation rate. Therefore, by using the actual volume and the carbon dioxide concentration in the storage space air, the carbon dioxide generation rate can be estimated with high accuracy.

[0029] The twelfth embodiment is one of the sixth to eighth embodiments, in which the controller (110) determines a target concentration to bring the oxygen concentration in the air inside the chamber to a set value. In concentration control, the controller (110) adjusts the oxygen concentration of the first air to the target concentration.

[0030] In the twelfth embodiment, the oxygen concentration in the air inside the chamber is adjusted to a target concentration, thereby bringing the oxygen concentration to a set value.

[0031] In the thirteenth aspect, as in the twelfth aspect, the controller (110) estimates the oxygen consumption rate of fruits, vegetables, or flowers in the storage space (5). The controller (110) determines a target concentration based on the oxygen consumption rate.

[0032] In the 13th embodiment, the target oxygen concentration required for the oxygen concentration in the warehouse air to reach a set value is determined based on the oxygen consumption rate of fruits, vegetables, or flowers. This is because the oxygen concentration in the warehouse air is affected by the oxygen consumption rate of the cargo. This allows the oxygen concentration in the warehouse air to quickly approach the set value.

[0033] In the fourteenth aspect, as in the thirteenth aspect, the controller (110) estimates the oxygen consumption rate based on the actual volume of the interior space (5) and the oxygen concentration in the air inside the interior.

[0034] In the 14th embodiment, the oxygen consumption rate of fruits, vegetables, or flowers is estimated based on the actual volume of the internal space (5) and the oxygen concentration in the internal air. The oxygen concentration in the internal air is affected by the actual volume of the internal space (5) and the oxygen consumption rate. Therefore, by using the actual volume and the oxygen concentration in the internal air, the oxygen consumption rate can be estimated with high accuracy.

[0035] In the 15th aspect, in the 11th or 14th aspect, the air composition adjustment device (90) further comprises a pressure adjustment unit (231) for changing the pressure in the internal space (5) and a pressure detection unit (170) for detecting the internal pressure in the internal space (5). The controller (110) estimates the actual volume based on a first index indicating the rate of change of the internal pressure when the internal pressure changes.

[0036] In the 15th embodiment, the pressure adjustment unit (231) changes the internal pressure (Pi). When cargo is loaded into the internal space (5) and the actual volume of the internal space (5) changes, the rate of change of the internal pressure (Pi) changes. Specifically, if the actual volume (Vs) increases, the rate of increase or decrease of the internal pressure (Pi) slows down, and if the actual volume (Vs) decreases, the rate of increase or decrease of the internal pressure (Pi) speeds up. Therefore, the controller (110) estimates the actual volume of the internal space (5) based on a first index that indicates the rate of change of the internal pressure (Pi).

[0037] The sixteenth embodiment is the air composition adjustment device in the first to fifteenth embodiments, further comprising concentration sensors (161, 162) for detecting the carbon dioxide concentration or oxygen concentration in the air inside the chamber. The controller (110) adjusts the flow rate of the first air in flow rate control so that the concentration detected by the concentration sensors (161, 162) reaches a set value.

[0038] In the sixteenth embodiment, the flow rate of the first air is adjusted in the flow control so that the concentration detected by the concentration sensors (161, 162) reaches a set value. This allows the carbon dioxide concentration and oxygen concentration in the air inside the chamber to be brought closer to the set value with high accuracy.

[0039] The 17th embodiment is the air composition control device, in the sixth to eighth embodiments, further comprising concentration sensors (161, 162) for detecting the carbon dioxide concentration or oxygen concentration in the air inside the chamber. The controller (110) adjusts the concentration of the first air in concentration control so that the concentration detected by the concentration sensors (161, 162) becomes a set value.

[0040] In the 17th aspect, in the concentration control, the concentration of the components of the first air is adjusted so that the detected concentration of the concentration sensors (161, 162) becomes the set value. Therefore, the carbon dioxide concentration and oxygen concentration in the air in the storage can be accurately brought close to the set value.

[0041] In the 18th aspect, in any one of the 1st to 17th aspects, the air composition adjusting device further includes a carbon dioxide sensor (162) that detects the carbon dioxide concentration in the air in the storage. The controller (110) is configured to obtain a target flow rate for setting the carbon dioxide concentration of the air in the storage to the set value. The controller (110) executes a first flow rate control as a flow rate control for adjusting the flow rate of the first air to the target flow rate, and a second flow rate control as a flow rate control for adjusting the flow rate of the first air so that the detected concentration of the carbon dioxide sensor (162) becomes the set value.

[0042] In the 18th aspect, in the first flow rate control, the flow rate of the first air is adjusted to the target flow rate for satisfying the set value. Therefore, the carbon dioxide concentration of the air in the storage can be quickly brought close to the set value. In the second flow rate control, the flow rate of the first air is adjusted so that the detected concentration of the carbon dioxide concentration sensors (161, 162) becomes the set value. Therefore, the carbon dioxide concentration of the air in the storage can be accurately brought close to the set value.

[0043] In the 19th aspect, in the 18th aspect, when a first condition indicating that the carbon dioxide concentration in the air in the storage is close to the set value does not hold, the controller (110) executes the first flow rate control. When the first condition holds, the controller (110) executes the second flow rate control.

[0044] In the 19th aspect, when a first condition indicating that the carbon dioxide concentration in the air in the storage is close to the set value does not hold, that is, when the carbon dioxide concentration in the air in the storage is away from the set value, the controller (110) executes the first flow rate control. As a result, the carbon dioxide concentration can be quickly brought close to the set value. When a first condition indicating that the carbon dioxide concentration in the air in the storage is close to the set value holds, the controller (110) executes the second flow rate control. As a result, the carbon dioxide concentration of the air in the storage can be accurately further brought close to the set value.

[0045] Aspect 20 includes an oxygen sensor (161) that detects the oxygen concentration in the air inside the storage. The controller (110) is configured to determine a target concentration for setting the oxygen concentration in the air inside the storage to a set value. The controller (110) performs a first concentration control as a concentration control for adjusting the oxygen concentration of the first air to the target concentration, and a second concentration control as a concentration control for adjusting the oxygen concentration of the first air so that the detected concentration of the oxygen concentration sensors (161, 162) becomes the set value.

[0046] In Aspect 20, in the first concentration control, the oxygen concentration of the first air is adjusted to a target concentration for satisfying the set value. Therefore, the oxygen concentration in the air inside the storage can be quickly brought close to the set value. In the second concentration control, the oxygen concentration of the first air is adjusted so that the detected concentration of the oxygen concentration sensors (161, 162) becomes the set value. Therefore, the oxygen concentration in the air inside the storage can be accurately brought close to the set value.

[0047] Aspect 21 is based on Aspect 20. The controller (110) performs the first concentration control when a second condition indicating that the oxygen concentration in the air inside the storage is close to the set value does not hold. The controller (110) performs the second concentration control when the second condition holds.

[0048] In Aspect 21, when the second condition indicating that the oxygen concentration in the air inside the storage is close to the set value does not hold, in other words, when the oxygen concentration in the air inside the storage is away from the set value, the controller (110) performs the first concentration control. As a result, the oxygen concentration can be quickly brought close to the set value. When the second condition indicating that the oxygen concentration in the air inside the storage is close to the set value holds, the controller (110) performs the second concentration control. As a result, the oxygen concentration in the air inside the storage can be accurately further brought close to the set value.

[0049] Aspect 22 is based on Aspect 15. The first index is an index indicating the rate of increase in the pressure inside the storage.

[0050] In the 22nd embodiment, the controller (110) estimates the actual volume of the internal space (5) based on a first indicator showing the rate of increase in the internal pressure.

[0051] The 23rd aspect is the 15th aspect, in which the first indicator is an indicator showing the rate of decrease in internal pressure.

[0052] In the 23rd embodiment, the controller (110) estimates the actual volume of the internal space (5) based on a first indicator that shows the rate of decrease in internal pressure.

[0053] The 24th aspect is the same as the 15th aspect, in which the interior space (5) is the interior space of the transport container (1). The controller (110) estimates the actual volume based on the airtightness index of the transport container (1) and a first index.

[0054] In the 24th embodiment, the controller (110) uses an airtightness index to determine the actual volume. This is because the airtightness index of the transport container (1), that is, the ease with which air leaks between the outside and inside of the container, affects the rate of change of the internal pressure.

[0055] In the 25th aspect, in the 24th aspect, the controller (110) performs a first airtightness measurement mode to determine the airtightness index based on the internal pressure, the external pressure of the external space (6), and an index indicating the rate of decrease in internal pressure when the internal pressure decreases.

[0056] In the 25th embodiment, in the first airtightness measurement mode, external pressure, internal pressure, and an index indicating the rate of decrease in internal pressure are used. This is because external pressure, internal pressure, and the rate of decrease in internal pressure are parameters that affect the airtightness index of the transport container (1).

[0057] In the 26th aspect, in the 24th aspect, the controller (110) performs a second airtightness measurement mode in which it determines an airtightness index based on the internal pressure, the external pressure of the external space (6), and an index indicating the rate of increase of the internal pressure when the internal pressure increases.

[0058] In the 26th embodiment, in the second airtightness measurement mode, external pressure, internal pressure, and an index indicating the rate of increase of the internal pressure are used. This is because external pressure, internal pressure, and the rate of increase of the internal pressure are parameters that affect the airtightness index of the transport container (1).

[0059] In the 27th embodiment, in the 25th or 26th embodiment, the controller (110) executes a first airtightness measurement mode or a second airtightness measurement mode when the storage space (5) is empty.

[0060] In the 27th embodiment, the first airtightness measurement mode or the second airtightness measurement mode is performed when the internal space (5) is empty. When the internal space (5) is empty, the actual volume (Vs) of the internal space (5) can be easily determined. Once the actual volume (Vs) is known, the airtightness index can be accurately determined because the actual volume (Vs) affects the rate of change of the internal pressure (Pi).

[0061] The 28th aspect is the same as the 24th aspect, in which the pressure adjustment unit is an air conveying unit (231) that supplies air to the internal space (5). The controller (110) performs a third airtightness measurement mode to determine an airtightness index based on the internal pressure, the external pressure of the external space (6), and the inflow rate of air supplied to the internal space (5) during a period when the internal pressure is constant while the air conveying unit (231) is in operation.

[0062] In the 28th embodiment, the airtightness index is determined based on the internal pressure, the external pressure, and the airflow rate supplied to the internal space, during a period when the internal pressure is constant. This is because, if the internal pressure is constant, these parameters will affect the airtightness index.

[0063] In the 29th aspect, in the 28th aspect, the controller (110) executes a third airtightness measurement mode when there is cargo in the storage space (5).

[0064] In the 29th embodiment, the third airtightness measurement mode is performed when there is cargo in the storage space (5). The third airtightness measurement mode is an airtightness index measured when the storage pressure (Pi) is constant and is not affected by the actual volume of the storage space (5). Therefore, even when there is cargo in the storage space (5), the airtightness index can be accurately determined.

[0065] In the 30th embodiment, in any one of the 15th, 22nd to 26th embodiments, the controller (110) estimates the actual volume based on the internal pressure, the external pressure of the external space (6), and a first indicator.

[0066] In the 30th embodiment, the controller (110) further uses the external pressure to estimate the actual volume of the internal space (5). This is because if there is an air leak in the internal space (6), the external pressure will affect the rate of change of the internal pressure.

[0067] The 31st embodiment is the 30th embodiment, in which the pressure detection unit includes a differential pressure sensor (170) that detects the differential pressure between the outside air and the inside air of the storage unit.

[0068] In the 31st embodiment, the differential pressure between the outside air and the inside air can be detected by the differential pressure sensor (170). Once the differential pressure between the two is known, and the outside pressure is considered to be atmospheric pressure, the inside pressure can be easily determined.

[0069] The 32nd embodiment is a transport refrigeration system comprising an air composition adjustment device (90) according to any one of the first to 31 embodiments and a refrigerant circuit (11) for cooling the internal space (5).

[0070] The 33rd embodiment is a transport container equipped with an air composition adjustment device (90) according to any one embodiment of the 1st to 32nd embodiments.

[0071] Figure 1 is a schematic perspective view of the transport refrigeration system of the embodiment. Figure 2 is a cross-sectional view of a transport container equipped with the transport refrigeration system of the embodiment. Figure 3 is a piping diagram showing the refrigerant circuit of the transport refrigeration system of the embodiment. Figure 4 is a schematic front view of the ventilation system. Figure 4(A) shows the lid in the closed position, Figure 4(B) shows the lid in the intermediate position, and Figure 4(C) shows the lid in the fully open position. Figure 5 is a piping diagram showing the configuration of the air composition control device of the embodiment. Figure 6 is a diagram corresponding to Figure 5 showing the air composition control device that performs the first operation of gas supply. Figure 7 is a diagram corresponding to Figure 5 showing the air composition control device that performs the second operation of gas supply. Figure 8 is a diagram corresponding to Figure 5 showing the air composition control device that performs the outside air introduction operation. Figure 9 is a block diagram showing the configuration of the controller included in the air composition control device of the embodiment. Figure 10 is a table showing the timing of operation in the 8% oxygen concentration mode. Figure 11 is a table showing the timing of operation in the 5% oxygen concentration mode. Figure 12 is a basic flowchart of the preliminary operation. Figure 13 shows a flowchart, timing chart, and formulas to explain the first airtight measurement mode. Figure 14 shows a flowchart, timing chart, and formulas to explain the second airtight measurement mode. Figure 15 shows a flowchart, timing chart, and formulas to explain the third airtight measurement mode. Figure 16 shows a flowchart, timing chart, and formulas to explain the first estimation operation. Figure 17 shows a flowchart, timing chart, and formulas to explain the second estimation operation. Figure 18 is a table showing the relationship between the operating modes of the air composition adjustment device and the first and second estimation operations. Figure 19 is a flowchart of the first respiratory volume estimation operation. Figure 20 is a flowchart of the second respiratory volume estimation operation. Figure 21 is a basic flowchart of the concentration adjustment mode. Figure 22 is a flowchart of flow rate control. Figure 23 is a flowchart of concentration control. Figure 24 is a timing chart showing the change in oxygen concentration of the processed gas during the first and second operations, and an example of control of the gas discharge valve and gas supply valve. Figure 25 is a diagram corresponding to Figure 5 of the transport container in Modification 1. Figure 26 is a diagram corresponding to Figure 5 of the transport container in Modification 3.Figure 27 is a conceptual diagram illustrating the timing of the airtightness measurement mode and estimation operation in the first example. Figure 28 is a conceptual diagram illustrating the timing of the airtightness measurement mode and estimation operation in the second example. Figure 29 is a flowchart of the first control example after estimating the actual volume in Modification 6. Figure 30 is a flowchart of the second control example after estimating the actual volume in Modification 7. Figure 31 is a diagram corresponding to Figure 2 of the transport container in Modification 8.

[0072] The embodiments of this disclosure will be described below with reference to the drawings. In the following description, the terms "front," "back," "up," "down," "right," and "left" refer to the directions indicated by the arrows in Figure 1.

[0073] (1) Overview This disclosure relates to a transport container (1). This transport container (1) is a reefer container that allows for temperature control inside the container. This transport container (1) uses oxygen (O) from the air. ２ ) absorbs carbon dioxide (CO2) ２ It is used to transport perishable goods (such as fruits, vegetables, and flowers) that respire by releasing fumes.

[0074] As shown in Figures 1 and 2, the transport container (1) comprises a container body (2) and a transport refrigeration unit (10). The transport refrigeration unit (10) is attached to the container body (2). The transport container (1) is used for maritime transport. The transport container (1) is transported by a maritime transport vehicle such as a ship.

[0075] The container body (2) is a storage unit for the fresh produce mentioned above.

[0076] The container body (2) is formed in the shape of a hollow box. The container body (2) is formed in a horizontal shape. An opening is formed at one end of the container body (2) in the longitudinal direction. The opening of the container body (2) is closed by a transport refrigeration device (10). Inside the container body (2), an interior space (5) is formed for storing perishable goods.

[0077] A floor plate (3) for loading cargo is placed at the bottom of the interior space (5). Between this floor plate (3) and the bottom plate of the container body (2), an underfloor passage (4) is formed for the air blown out by the transport refrigeration unit (10) to flow. The underfloor passage (4) is a passage that extends along the bottom plate of the container body (2) in the longitudinal direction of the container body (2). One end of the underfloor passage (4) is connected to the outlet (27) of the transport refrigeration unit (10), and the other end is in communication with the space above the floor plate (3) (i.e., the space where the cargo is stored).

[0078] (2) Basic configuration of transport refrigeration equipment The transport refrigeration equipment (10) comprises a casing (20), a refrigerant circuit (11) that performs the refrigeration cycle, an external fan (34), and an internal fan (35).

[0079] (2-1) Casing The casing (20) comprises an outer wall section (21), an inner wall section (22), a back panel (24), and a partition panel (25). As will be described later, this casing (20) is provided with a refrigerant circuit (11), an outer fan (34), and an inner fan (35).

[0080] The outer wall portion (21) is a plate-shaped member positioned to cover the open end of the container body (2). The lower part of the outer wall portion (21) bulges inward into the container body (2). The inner wall portion (22) is a plate-shaped member that follows the shape of the outer wall portion (21). The inner wall portion (22) is positioned to cover the inner surface of the outer wall portion (21) of the container body (2). The space between the outer wall portion (21) and the inner wall portion (22) is filled with insulation material (23).

[0081] The casing (20) has a shape in which its lower part is recessed inward into the container body (2). The lower part of the casing (20) forms an external equipment room (28) that communicates with the external space of the transport container (1). An external fan (34) is located in this external equipment room (28).

[0082] The back panel (24) is a generally rectangular, flat member. The back panel (24) is positioned inside the container body (2) relative to the interior wall (22), and forms an internal air passage (29) between the back panel (24) and the interior wall (22). The upper end of this internal air passage (29) constitutes the intake port (26) of the casing (20), and the lower end constitutes the outlet port (27) of the casing (20).

[0083] The partition plate (25) is a plate-shaped member positioned to divide the internal air passage (29) vertically. The partition plate (25) is positioned above the internal air passage (29). This partition plate (25) divides the internal air passage (29) into a primary passage (29a) above the partition plate (25) and a secondary passage (29b) below the partition plate (25). The primary passage (29a) communicates with the internal space (5) via an intake port (26). The secondary passage (29b) communicates with the underfloor passage (4) via an outlet port (27). An internal fan (35) is attached to the partition plate (25). The internal fan (35) is positioned to draw in air from the primary passage (29a) and blow it out into the secondary passage (29b).

[0084] (2-2) Refrigerant Circuit As shown in Figure 3, the refrigerant circuit (11) is a closed circuit formed by connecting the compressor (12), the external heat exchanger (13), the expansion valve (14), and the internal heat exchanger (15) with piping. When the compressor (12) is operated, the refrigerant circulates through the refrigerant circuit (11), and a vapor compression refrigeration cycle is performed. As shown in Figure 2, the external heat exchanger (13) is located in the external equipment room (28), and the internal heat exchanger (15) is located in the secondary flow path (29b) of the internal air flow path (29). The compressor (12) is located in the external equipment room (28).

[0085] (2-3) Operation of the transport refrigeration system The transport refrigeration system (10) performs a cooling operation to cool the air inside the transport container (1).

[0086] During cooling operation, the compressor (12) of the refrigerant circuit (11) operates, and the refrigerant circulates in the refrigerant circuit (11), performing a vapor compression refrigeration cycle. In the refrigerant circuit (11), the refrigerant discharged from the compressor (12) passes sequentially through the external heat exchanger (13), the expansion valve (14), and the internal heat exchanger (15), and is then drawn into the compressor (12) and compressed.

[0087] During cooling operation, the external fan (34) and the internal fan (35) operate. When the external fan (34) operates, outside air from the outside of the transport container (1) is drawn into the external equipment room (28) and passes through the external heat exchanger (13). In the external heat exchanger (13), the refrigerant releases heat to the outside air and condenses. When the internal fan (35) operates, the internal air from the internal space (5) of the transport container (1) is drawn into the internal air passage (29) and passes through the internal heat exchanger (15). In the internal heat exchanger (15), the refrigerant absorbs heat from the internal air and evaporates.

[0088] Let's explain the airflow inside the storage area. The air present in the storage area (5) flows through the intake port (26) into the primary flow path (29a) of the storage area airflow path (29), and is blown out into the secondary flow path (29b) by the storage area fan (35). The air that flows into the secondary flow path (29b) is cooled as it passes through the storage area heat exchanger (15), and is then blown out from the outlet (27) into the underfloor flow path (4), and flows back into the storage area (5) through the underfloor flow path (4).

[0089] In the internal air passage (29), the primary passage (29a) is located on the intake side of the internal fan (35), and the secondary passage (29b) is located on the outlet side of the internal fan (35). Therefore, when the internal fan (35) is operating, the air pressure in the secondary passage (29b) is slightly higher than the air pressure in the primary passage (29a).

[0090] (3) Ventilation equipment The transport refrigeration equipment (10) is equipped with a ventilation device (40). The ventilation device (40) ventilates the interior space (5) of the container body (2). The ventilation device (40) has an air supply function that supplies outside air to the interior space (5) and an exhaust function that discharges the interior air to the outside space (6).

[0091] (3-1) Configuration of the ventilation device As shown in Figure 1, the ventilation device (40) is located in the upper left part of the casing (20) of the transport refrigeration device (10). As shown in Figure 2, the ventilation device (40) is installed in a ventilation opening (38) formed in the casing (20). The ventilation opening (38) penetrates the casing (20) in the front-to-back direction.

[0092] As shown in Figure 2, an air supply passage (41) and an exhaust passage (42) are formed inside the ventilation device (40). The air supply passage (41) and the exhaust passage (42) connect the interior space (5) and the exterior space (6).

[0093] Specifically, the air supply passage (41) connects the primary air passage (29a) of the internal air passage (29) to the external space (6). The end of the air supply passage (41) on the external space (6) side is the air supply port (41a). The air supply port (41a) is an air inlet that connects the external space (6) to the inside of the container body (2). The exhaust passage (42) connects the secondary air passage (29b) of the internal air passage (29) to the external space (6). The end of the exhaust passage (42) on the external space (6) side is the exhaust port (42a). The air supply port (41a) and the exhaust port (42a) are somewhat elongated openings that extend in the circumferential direction.

[0094] The ventilation device (40) includes an opening / closing cover (45). The opening / closing cover (45) is a disc-shaped member. The opening / closing cover (45) is provided to cover the air supply port (41a) and the exhaust port (42a). The opening / closing cover (45) is driven by a motor (not shown) and is rotatable around its central axis.

[0095] As shown in Figure 4, the opening / closing lid (45) has an air intake opening (46) and an exhaust opening (47). Both the air intake opening (46) and the exhaust opening (47) penetrate the opening / closing lid (45) in the thickness direction. The shape of the air intake opening (46) is the same as the shape of the air intake port (41a). The shape of the exhaust opening (47) is the same as the shape of the exhaust port (42a). In the opening / closing lid (45), the air intake opening (46) and the exhaust opening (47) are formed in such a position that when the entire air intake opening (46) overlaps with the air intake port (41a), the entire exhaust opening (47) overlaps with the exhaust port (42a).

[0096] (3-2) Operation of the ventilation device The ventilation device (40) is configured to adjust the flow rate of outside air supplied to the interior space (5) (supply air flow rate) and the flow rate of inside air discharged from the interior space (5) (exhaust air flow rate) by rotating the opening and closing lid (45).

[0097] Specifically, when the opening / closing lid (45) is rotated, the area of ​​the portion of the air supply port (41a) that overlaps with the air supply opening (46) and the area of ​​the portion of the exhaust port (42a) that overlaps with the exhaust opening (47) change. Outside air flows into the air supply passage (41) through the portion of the air supply port (41a) that overlaps with the air supply opening (46), and then flows into the interior space (5). Inside air flowing through the exhaust passage (42) flows out into the exterior space (6) through the portion of the exhaust port (42a) that overlaps with the exhaust opening (47).

[0098] Increasing the area of ​​the portion of the air supply port (41a) that overlaps with the air supply opening (46) increases the air supply flow rate, while decreasing the area of ​​that portion decreases the air supply flow rate. Increasing the area of ​​the portion of the exhaust port (42a) that overlaps with the exhaust opening (47) increases the exhaust flow rate, while decreasing the area of ​​that portion decreases the exhaust flow rate.

[0099] When the opening / closing cover (45) is in the position shown in Figure 4(A), the entire air supply port (41a) is covered by the opening / closing cover (45), and the entire exhaust port (42a) is also covered by the opening / closing cover (45). As a result, the area of ​​the portion of the air supply port (41a) that overlaps with the air supply opening (46) and the area of ​​the portion of the exhaust port (42a) that overlaps with the exhaust opening (47) become zero. In other words, the air supply passage (41) and the exhaust passage (42) become completely closed. Therefore, in this state, both the air supply flow rate and the exhaust flow rate become zero.

[0100] When the opening / closing cover (45) is in the position shown in Figure 4(C), the entire intake port (41a) overlaps with the intake opening (46), and the entire exhaust port (42a) overlaps with the exhaust opening (47). Therefore, the area of ​​the portion of the intake port (41a) that overlaps with the intake opening (46) (the dotted portion in Figure 4(C)) and the area of ​​the portion of the exhaust port (42a) that overlaps with the exhaust opening (47) (the dotted portion in Figure 4(C)) are both maximized. In other words, the intake passage (41) and the exhaust passage (42) are fully open. Consequently, in this state, both the intake air flow rate and the exhaust air flow rate reach their maximum flow rates.

[0101] When the opening / closing cover (45) is in the position shown in Figure 4(B), a portion of the air intake port (41a) overlaps with the air intake opening (46), and a portion of the exhaust port (42a) overlaps with the exhaust opening (47). As a result, the area of ​​the portion of the air intake port (41a) that overlaps with the air intake opening (46) (the dotted portion in Figure 4(B)) and the area of ​​the portion of the exhaust port (42a) that overlaps with the exhaust opening (47) (the dotted portion in Figure 4(B)) are both intermediate areas smaller than the maximum. Therefore, in this state, both the air intake flow rate and the exhaust flow rate are intermediate flow rates that are greater than zero and less than the maximum flow rate.

[0102] (4) Air composition adjustment device The air composition adjustment device (100) generates a gas to be treated that has a different composition from the outside air by processing the outside air, which is the ambient air. The air composition adjustment device (100) supplies the generated gas to be treated into the interior space (5) of the container body (2).

[0103] (4-1) Basic configuration of the air composition control device The air composition control device (100) is installed in the transport refrigeration device (10) for so-called CA (Controlled Atmosphere) transport. The air composition control device (100) adjusts the air composition in the interior space (5) of the transport container (1).

[0104] As shown in Figure 5, the air composition adjustment device (100) comprises a filter unit (220), a main unit (200), a gas supply pipe (275), a gas discharge pipe (276), a sensor unit (160), and a ventilation exhaust pipe (150). The air composition adjustment device (100) is a so-called PSA (Pressure Swing Adsorption) type gas separation device.

[0105] The air composition adjustment device (100) generates the gas to be treated by processing the outside air, which is the ambient air. Specifically, the air composition adjustment device (100) separates the outside air into a nitrogen-enriched gas, which has a higher nitrogen concentration and a lower oxygen concentration than the outside air, and an oxygen-enriched gas, which has a lower nitrogen concentration and a higher oxygen concentration than the outside air.

[0106] The air composition adjustment device (90) includes a supply passage (S) that connects the external space (6) and the internal space (5) inside the container body (2), which is a storage compartment; an air processing unit (95) that adjusts the composition of the external air; and an air pump (231) that transports the air in the supply passage (S) to the internal space (5) as first air. The supply passage (S) is composed of a plurality of pipes that connect the external space (6) and the internal space (5). The plurality of pipes include an external air pipe (241), an inlet pipe (242), a first gas pipe (244), a bypass connecting pipe (255), and a gas supply pipe (275). The air pump (231) is an example of an air transport unit. The first gas pipe (244) and the gas supply pipe (275) are examples of a first flow path.

[0107] (4-2) The filter unit and the outside air pipe filter unit (220) are box-shaped components. The filter unit (220) is installed in the outside equipment room (28) of the transport refrigeration unit (10). The filter unit (220) includes an air filter (221). The air filter (221) is a filter for capturing dust, salt, and other particles contained in the outside air. The air filter (221) in this embodiment is a membrane filter that has both breathability and waterproofing properties.

[0108] The filter unit (220) is connected to the main unit (200) via an outside air pipe (241). One end of the outside air pipe (241) is connected to the filter unit (220). The other end of the outside air pipe (241) is connected to an air pump (231), which will be described later. The outside air pipe (241) guides the outside air (atmosphere) that has passed through the air filter (221) to the air pump (231).

[0109] (4-3) Main Unit The main unit (200) is installed in the external equipment room (28) of the transport refrigeration system (10). The main unit (200) comprises an air pump (231), a first suction cylinder (234), a second suction cylinder (235), a first switching valve (232), a second switching valve (233), and a unit case (201) that houses these. The unit case (201) houses an inlet pipe (242), a suction pipe (243), a first gas pipe (244), and a second gas pipe (245).

[0110] (4-4) Air Pump The air pump (231) comprises a pressurizing pump (231a), a depressurizing pump (231b), and a drive motor (231c). The pressurizing pump (231a) and the depressurizing pump (231b) each draw in and discharge air. The pressurizing pump (231a) and the depressurizing pump (231b) are connected to the drive shaft of a single drive motor (231c). In the air pump (231), both the pressurizing pump (231a) and the depressurizing pump (231b) are driven by a single drive motor (231c).

[0111] The other end of the outside air pipe (241) is connected to the intake port of the pressurizing pump (231a). One end of the inlet pipe (242) is connected to the discharge port of the pressurizing pump (231a). The pressurizing pump (231a) supplies the air to be treated, drawn in from the outside air pipe (241), to the first adsorption cylinder (234) and the second adsorption cylinder (235) through the inlet pipe (242).

[0112] A suction tube (243) is connected to the inlet of the pressure reducing pump (231b). A first gas pipe (244) is connected to the discharge port of the pressure reducing pump (231b). The pressure reducing pump (231b) discharges the gas drawn in from the first adsorption cylinder (234) and the second adsorption cylinder (235) through the suction tube (243) into the first gas pipe (244).

[0113] The air pump (231) in this embodiment is of variable flow rate. Specifically, the air pump (231) is configured so that the rotational speed of the motor that rotates the pump body can be changed. The motor is an inverter type with adjustable operating frequency, but it may also be a geared motor with multi-stage rotational speed adjustment.

[0114] (4-5) Inlet pipe The inlet pipe (242) is a pipe that guides the air to be treated discharged by the pressurizing pump (231a) to the first adsorption cylinder (234) and the second adsorption cylinder (235). One end of the inlet pipe (242) is connected to the discharge port of the pressurizing pump (231a). The other end of the inlet pipe (242) branches into two branch pipes, one of which is connected to the first switching valve (232) and the other branch pipe is connected to the second switching valve (233).

[0115] (4-6) Suction pipe The suction pipe (243) is a pipe that guides the gas flowing out from the first adsorption cylinder (234) and the second adsorption cylinder (235) to the pressure reducing pump (231b). One end of the suction pipe (243) is connected to the suction port of the pressure reducing pump (231b). The other end of the suction pipe (243) branches into two branch pipes, one of which is connected to the first switching valve (232) and the other branch pipe is connected to the second switching valve (233).

[0116] (4-7) First gas pipe The first gas pipe (244) is the piping through which nitrogen-enriched gas discharged from the pressure reducing pump (231b) flows. One end of the first gas pipe (244) is connected to the discharge port of the pressure reducing pump (231b). The other end of the first gas pipe (244) is connected to the gas supply pipe (275).

[0117] A check valve (264) is provided in the first gas pipe (244). This check valve (264) allows gas to flow only in the direction from one end to the other of the first gas pipe (244), and blocks gas flow in the reverse direction.

[0118] (4-8) Switching valves The first switching valve (232) and the second switching valve (233) are each switching valves having three ports. The first switching valve (232) and the second switching valve (233) are configured to switch between a first state (shown by a solid line in Figure 3) in which the first port communicates with the second port and is blocked from the third port, and a second state (shown by a dashed line in Figure 3) in which the first port communicates with the third port and is blocked from the second port.

[0119] The first switching valve (232) has a first port connected to one end of the first suction cylinder (234). The first switching valve (232) also has a second port connected to a branch pipe of the inlet pipe (242) and a third port connected to a branch pipe of the suction pipe (243). The first switching valve (232) switches the first suction cylinder (234) between being connected to the pressurizing pump (231a) and being connected to the depressurizing pump (231b).

[0120] The second switching valve (233) has its first port connected to one end of the second suction cylinder (235). The second switching valve (233) also has a branch pipe of the inlet pipe (242) connected to its second port and a branch pipe of the suction pipe (243) connected to its third port. The second switching valve (233) switches the second suction cylinder (235) between being connected to the pressurizing pump (231a) and being connected to the depressurizing pump (231b).

[0121] (4-9) Adsorption cylinders The first adsorption cylinder (234) and the second adsorption cylinder (235) are adsorption units comprising a cylindrical container with both ends closed and an adsorbent filled in the container. The adsorption cylinders (234, 235) use the adsorbent to separate the air to be treated (in this embodiment, outside air) into oxygen-enriched gas and nitrogen-enriched gas.

[0122] The adsorbent packed into the adsorption cylinders (234, 235) has the property of adsorbing nitrogen and water (water vapor) from the air to be treated under pressurized conditions where the pressure is higher than atmospheric pressure, and desorbing nitrogen and water under reduced pressure conditions where the pressure is lower than atmospheric pressure. An example of an adsorbent with such properties is a porous zeolite having pores with a diameter smaller than the molecular diameter of a nitrogen molecule (3.0 angstroms) and larger than the molecular diameter of an oxygen molecule (2.8 angstroms).

[0123] The first suction cylinder (234) and the second suction cylinder (235), together with the first switching valve (232) and the second switching valve (233), constitute an air processing unit (95).

[0124] (4-10) The second gas pipe (245) comprises a main pipe (246), a first branch pipe (247a), and a second branch pipe (247b). The second gas pipe (245) constitutes the first passage through which oxygen-enriched gas flows. The first branch pipe (247a) is a pipe that connects the other end of the first adsorption cylinder (234) to one end of the main pipe (246). The second branch pipe (247b) is a pipe that connects the other end of the second adsorption cylinder (235) to one end of the main pipe (246). Each of the first branch pipe (247a) and the second branch pipe (247b) is provided with one check valve (261). Each check valve (261) allows airflow in the direction of outflow from the corresponding adsorption cylinder (234, 235) and blocks airflow in the reverse direction.

[0125] As described above, the first branch pipe (247a) and the second branch pipe (247b) are connected to one end of the main pipe (246). The other end of the main pipe (246) is connected to the gas discharge pipe (276), which will be described later. The main pipe (246) is provided with an orifice (263) and a check valve (262) in that order from one end to the other. The check valve (262) allows air to flow from one end to the other of the main pipe (246) and blocks air to flow in the reverse direction.

[0126] (4-11) A purge pipe (250) is connected to each of the first branch pipe (247a) and the second branch pipe (247b) of the second gas pipe (245). One end of the purge pipe (250) is connected to the first branch pipe (247a), and the other end is connected to the second branch pipe (247b). One end of the purge pipe (250) is connected between the first suction cylinder (234) and the check valve (261) in the first branch pipe (247a). The other end of the purge pipe (250) is connected between the second suction cylinder (235) and the check valve (261) in the second branch pipe (247b).

[0127] A purge valve (251) is provided in the purge pipe (250). The purge valve (251) is an on / off valve consisting of a solenoid valve. The purge valve (251) is opened when equalizing the pressure between the first adsorption cylinder (234) and the second adsorption cylinder (235). In addition, one orifice (252) is provided on each side of the purge valve (251) in the purge pipe (250).

[0128] (4-12) Exhaust connection pipe An exhaust connection pipe (271) is connected to the first gas pipe (244). The exhaust connection pipe (271) is an example of a second flow path. One end of the exhaust connection pipe (271) is connected to the first gas pipe (244), and the other end is connected to the second gas pipe (245). One end of the exhaust connection pipe (271) is connected between the pressure reducing pump (231b) and the check valve (264) in the first gas pipe (244). The other end of the exhaust connection pipe (271) is connected to one end of the gas discharge pipe (276).

[0129] A gas discharge valve (272) is provided in the exhaust connecting pipe (271). The gas discharge valve (272) is an on / off valve consisting of a solenoid valve. When the gas discharge valve (272) is opened, the nitrogen-enriched gas flowing through the first gas pipe (244) is discharged to the outside of the container body (2).

[0130] (4-13) Gas supply pipe As described above, the first gas pipe (244) is connected to one end of the gas supply pipe (275). The gas supply pipe (275) extends to the outside of the unit case (201). The other end of the gas supply pipe (275) opens downstream of the internal fan (35) in the internal air passage (29) of the transport refrigeration unit (10). The gas supply pipe (275) is a pipe for introducing the gas that flows in from one end into the inside of the container body (2).

[0131] A gas supply valve (273) is provided in the gas supply pipe (275). The gas supply valve (273) is an on / off valve consisting of a solenoid valve.

[0132] (4-14) Gas discharge pipe As described above, one end of the gas discharge pipe (276) is connected to the main pipe (246) of the second gas pipe (245) and the exhaust connecting pipe (271). The gas discharge pipe (276) extends to the outside of the unit case (201). The other end of the gas discharge pipe (276) opens to the external equipment room (28) of the transport container (1). The gas discharge pipe (276) is a pipe for discharging the gas that has flowed in from one end to the outside of the container body (2).

[0133] (4-15) Measurement piping A measurement piping (281) is connected to the first gas pipe (244). The measurement piping (281) is the piping that connects the first gas pipe (244) to the sensor unit (160). One end of the measurement piping (281) is connected to the downstream side of the check valve (264) in the first gas pipe (244). The other end of the measurement piping (281) is connected to the sensor unit (160).

[0134] A measuring valve (282) is provided in the measuring piping (281). The measuring valve (282) is a solenoid valve. The measuring valve (282) is opened when air flowing through the first gas pipe (244) is sent to the sensor unit (160).

[0135] (4-16) A bypass connecting pipe (255) is connected to the bypass inlet pipe (242). The bypass connecting pipe (255) is a pipe that bypasses the first adsorption cylinder (234) and the second adsorption cylinder (235) to supply outside air to the interior space (5) of the transport container (1). The bypass connecting pipe (255) is an example of a third flow path. One end of the bypass connecting pipe (255) is connected between the branching point of the inlet pipe (242) and the pressurizing pump (231a). The other end of the bypass connecting pipe (255) is connected to one end of the gas supply pipe (275).

[0136] A bypass valve (256) is provided in the bypass connecting pipe (255). The bypass valve (256) is an on / off valve consisting of a solenoid valve. This bypass valve (256) is opened when the outside air discharged by the pressurizing pump (231a) is supplied to the interior space (5) without changing its composition.

[0137] (4-17) Sensor Unit The sensor unit (160) comprises an oxygen sensor (161), a carbon dioxide sensor (162), and a sensor case (163). The sensor unit (160) is a detector that detects the concentration of components in the air inside the chamber. The sensor unit (160) is installed in the secondary flow path (29b) of the internal air flow path (29).

[0138] The oxygen sensor (161) is a zirconia current type concentration sensor that measures the oxygen concentration of a gas mixture such as air. The carbon dioxide sensor (162) is a non-dispersive infrared (NDIR) type concentration sensor that measures the carbon dioxide concentration of a gas mixture such as air. The oxygen sensor (161) and the carbon dioxide sensor (162) are housed in a sensor case (163).

[0139] The sensor case (163) is a box-shaped component. The sensor case (163) is equipped with an air filter (164). The air filter (164) is a membrane filter for capturing dust and other particles contained in the air inside the chamber. The air filter (164) filters the air inside the chamber that flows into the sensor case (163).

[0140] A measuring pipe (281) is connected to the sensor case (163). An outlet pipe (165) is connected to the sensor case (163). The outlet pipe (165) has an inlet end connected to the sensor case (163) and an outlet end that opens upstream of the internal fan (35) in the internal air passage (29). The outlet end of the outlet pipe (165) opens into the primary passage (29a) of the internal air passage (29).

[0141] When the measuring valve (282) is closed, the air inside the storage chamber flows through the sensor case (163). Specifically, the air inside the storage chamber flows through the secondary flow path (29b) of the storage chamber air passage (29), passes through the air filter (164) and flows into the sensor case (163), then passes through the sensor case (163) and flows through the outlet pipe (165) and into the primary flow path (29a) of the storage chamber air passage (29). Therefore, when the measuring valve (282) is closed, the oxygen sensor (161) measures the oxygen concentration of the air inside the storage chamber, and the carbon dioxide sensor (162) measures the carbon dioxide concentration of the air inside the storage chamber.

[0142] On the other hand, when the measuring valve (282) is open, the gas flowing through the measuring pipe (281) flows inside the sensor case (163). Specifically, the gas flowing through the first gas pipe (244) or the bypass connecting pipe (255) flows through the measuring pipe (281) into the sensor case (163), passes through the sensor case (163), flows through the outlet pipe (165), and flows into the primary flow path (29a) of the internal air passage (29). Therefore, when the measuring valve (282) is open, the oxygen sensor (161) measures the oxygen concentration of the gas that has flowed from the measuring pipe (281) into the sensor case (163), and the carbon dioxide sensor (162) measures the carbon dioxide concentration of the gas that has flowed from the measuring pipe (281) into the sensor case (163).

[0143] (4-18) Ventilation exhaust pipe The ventilation exhaust pipe (150) is a pipe for discharging the internal air of the transport container (1) to the outside space. The ventilation exhaust pipe (150) penetrates the external wall (21) and internal wall (22) of the transport refrigeration unit (10). A ventilation exhaust valve (151) is provided in the ventilation exhaust pipe (150). The ventilation exhaust valve (151) is an on / off valve consisting of a solenoid valve.

[0144] (4-19) Differential pressure sensor and internal temperature sensor air composition control device (100) has a differential pressure sensor (170) as a pressure detection unit. The differential pressure sensor (170) is used to detect the pressure in the internal space (5). The differential pressure sensor (170) detects the differential pressure (ΔP) between the internal pressure (Pi) in the internal space (5) and the external pressure (Po) in the external space (6). As shown in Figures 2 and 5, the differential pressure sensor (170) is placed in the internal space (5). Specifically, the differential pressure sensor (170) is placed in the primary flow path (29a) of the internal air flow path (29). The differential pressure sensor (170) includes a main body case (171), a sensor unit (172) located inside the main body case (171), an internal communication passage (173) connecting the inside of the main body case (171) to the internal storage space (5), and an external communication passage (174) connecting the inside of the main body case (171) to the external storage space (6).

[0145] The internal communication passage (173) is composed of a communication hole formed in the main body case (171). In this embodiment, the internal communication passage (173) opens toward the primary flow path (29a). More specifically, the internal communication passage (173) opens toward the primary flow path (29a) so as to face away from the intake side of the internal fan (35). This suppresses the influence of the dynamic pressure of the internal air flowing through the internal air passage (29) on the detection value of the differential pressure sensor (170). The external communication passage (174) is formed inside the tube. The tube extends from the main body case (171) to the external space (6). The differential pressure sensor (170) detects the differential pressure ΔP between the internal space (5) and the external space (6).

[0146] The air composition control device (100) has an internal temperature sensor (51). The internal temperature sensor (51) detects the temperature of the air inside the chamber. The internal temperature sensor (51) is positioned in the primary flow path (29a) of the internal air flow path (29).

[0147] (5) Operation of the air composition control device (5-1) Gas supply operation The air composition control device (100) performs a gas supply operation. The gas supply operation is the operation of generating nitrogen-enriched gas by processing the outside air and supplying this nitrogen-enriched gas to the inside space (5). During the gas supply operation, the ventilation exhaust valve (151) is opened.

[0148] During the gas supply operation, the air composition adjustment device (100) repeatedly performs the first operation and the second operation alternately. The air composition adjustment device (100) repeatedly performs the first operation and the second operation alternately for a predetermined switching time (for example, 14 seconds). As a result, in the air processing unit (95) of the air composition adjustment device (100), the outside air is separated into nitrogen-enriched gas and oxygen-enriched gas.

[0149] (5-1-1) As shown in the first operation diagram 6, in the first operation, the first switching valve (232) is set to the first state and the second switching valve (233) is set to the second state. Also in the first operation, the purge valve (251), the bypass valve (256), and the measuring on / off valve (282) are held in the closed state. In the first operation, the air pump (231) is activated and an adsorption operation is performed on the first adsorption cylinder (234) and a detachment operation is performed on the second adsorption cylinder (235).

[0150] The pressurizing pump (231a) draws in outside air (atmosphere) from the outside air pipe (241), pressurizes it, and supplies the pressurized outside air to the first adsorption cylinder (234). In the first adsorption cylinder (234), nitrogen and water (water vapor) contained in the supplied outside air are adsorbed by the adsorbent. As a result, oxygen-enriched gas with a lower nitrogen concentration and a higher oxygen concentration than the outside air is produced in the first adsorption cylinder (234). The oxygen-enriched gas flows out from the first adsorption cylinder (234) to the first branch pipe (247a) of the second gas pipe (245), and is then discharged to the outside space (6) through the gas discharge pipe (276).

[0151] Meanwhile, the depressurization pump (231b) draws gas from the second adsorption cylinder (235). In the second adsorption cylinder (235), the internal pressure decreases, causing nitrogen and water to desorb from the adsorbent. As a result, nitrogen-enriched gas is generated in the second adsorption cylinder (235) with a higher nitrogen concentration and lower oxygen concentration than the outside air. The nitrogen-enriched gas flows from the second adsorption cylinder (235) into the suction pipe (243) and is drawn into the depressurization pump (231b). The depressurization pump (231b) pressurizes the drawn-in nitrogen-enriched gas and discharges it into the first gas pipe (244). The nitrogen-enriched gas flowing through the first gas pipe (244) is supplied to the interior space (5) through the gas supply pipe (275).

[0152] (5-1-2) As shown in the second operation diagram 7, in the second operation, the first switching valve (232) is set to the second state and the second switching valve (233) is set to the first state. Also in the second operation, the purge valve (251), the bypass valve (256), and the measuring on / off valve (282) are held in the closed state. Then, in the second operation, the air pump (231) is activated and a detachment operation targeting the first suction cylinder (234) and an adsorption operation targeting the second suction cylinder (235) are performed.

[0153] The pressurizing pump (231a) draws in outside air (atmosphere) from the outside air pipe (241), pressurizes it, and supplies the pressurized outside air to the second adsorption cylinder (235). In the second adsorption cylinder (235), nitrogen and water (water vapor) contained in the supplied outside air are adsorbed by the adsorbent. As a result, oxygen-enriched gas with a lower nitrogen concentration and a higher oxygen concentration than the outside air is produced in the second adsorption cylinder (235). The oxygen-enriched gas flows out from the second adsorption cylinder (235) to the second branch pipe (247b) of the second gas pipe (245), and is then discharged to the outside space (6) through the gas discharge pipe (276).

[0154] Meanwhile, the depressurization pump (231b) draws gas from the first adsorption cylinder (234). In the first adsorption cylinder (234), the internal pressure decreases, causing nitrogen and water to desorb from the adsorbent. As a result, nitrogen-enriched gas is generated in the first adsorption cylinder (234) with a higher nitrogen concentration and lower oxygen concentration than the outside air. The nitrogen-enriched gas flows from the first adsorption cylinder (234) into the suction pipe (243) and is drawn into the depressurization pump (231b). The depressurization pump (231b) pressurizes the drawn-in nitrogen-enriched gas and discharges it into the first gas pipe (244). The nitrogen-enriched gas flowing through the first gas pipe (244) is supplied to the interior space (5) through the gas supply pipe (275).

[0155] (5-2) Outside air introduction operation The air composition adjustment device (100) performs an outside air introduction operation. The outside air introduction operation is an operation that supplies outside air, which is the atmosphere, to the inside space (5) of the storage facility without changing its composition.

[0156] As shown in Figure 8, during the outside air intake operation, both the first switching valve (232) and the second switching valve (233) are set to the second state. Also, during the outside air intake operation, the gas supply valve (273) and the bypass valve (256) are held in the open state, and the remaining on / off valves (251, 272, 282) are held in the closed state. In addition, during the outside air intake operation, the air pump (231) is activated and the ventilation exhaust valve (151) is opened.

[0157] The pressurizing pump (231a) draws in outside air (atmosphere) from the outside air pipe (241), pressurizes it, and discharges the pressurized outside air to the inlet pipe (242). The outside air discharged from the pressurizing pump (231a) flows sequentially through the inlet pipe (242), the bypass connecting pipe (255), and the gas supply pipe (275), and is supplied to the internal air passage (29). In this way, during the outside air intake operation, air with the same composition as the atmosphere is supplied to the internal space (5) of the transport container (1).

[0158] The pressure reducing pump (231b) draws gas from both the first adsorption cylinder (234) and the second adsorption cylinder (235), and discharges the drawn-in gas to the first gas pipe (244). The gas discharged by the pressure reducing pump (231b) to the first gas pipe (244) flows into the gas supply pipe (275) and, together with the outside air that flows into the gas supply pipe (275) from the bypass connecting pipe (255), is supplied to the internal air passage (29).

[0159] When the depressurizing pump (231b) draws gas from the first adsorption cylinder (234) and the second adsorption cylinder (235), the pressure in the first adsorption cylinder (234) and the second adsorption cylinder (235) gradually decreases. Then, once the duration of the outside air intake operation exceeds a certain period of time (for example, 45 seconds), the flow rate of gas drawn in by the depressurizing pump (231b) becomes virtually zero.

[0160] (6) The air composition control device (100) has a controller (110). As shown in Figure 9, the controller (110) includes a microcomputer (111) mounted on a control board and a memory device (112) that stores software for operating the microcomputer (111). The memory device (112) is a semiconductor memory.

[0161] The controller (110) controls the components of the air composition control device (100). The controller (110) receives the measured values ​​from the oxygen sensor (161) and the carbon dioxide sensor (162). The controller (110) controls the air pump (231), the first switching valve (136), and the second switching valve (137). The controller (110) also controls the ventilation exhaust valve (151), the purge valve (251), the bypass valve (256), the gas discharge valve (272), the gas supply valve (273), and the measuring on / off valve (282).

[0162] The controller (110) controls the ventilation device (40). Specifically, the controller (110) adjusts the opening of the supply air port (41a) and the exhaust air port (42a) by rotating the opening / closing cover (45) of the ventilation device (40). Changing the opening of the supply air port (41a) changes the flow rate of outside air supplied to the interior space (5) through the supply air passage (41). Changing the opening of the exhaust air port (42a) changes the flow rate of inside air discharged to the exterior space (6) through the exhaust passage (42).

[0163] (7) Operating Modes The operating modes of the air composition control device (100) will be described below. The controller (110) causes the air composition control device (100) to perform five operating modes. These operating modes include an 8% oxygen concentration mode, a 5% oxygen concentration mode, an outside air intake mode, a breathing mode, and a concentration control mode.

[0164] The 8% oxygen concentration mode is an operating mode in which the air composition control device (100) supplies nitrogen-enriched gas with an average oxygen concentration of 8% to the interior space (5). The 5% oxygen concentration mode is an operating mode in which the air composition control device (100) supplies nitrogen-enriched gas with an average oxygen concentration of 5% to the interior space (5). The outside air introduction mode is an operating mode in which the air composition control device (100) supplies outside air directly to the interior space (5). The breathing mode is an operating mode in which the air composition control device (100) stops supplying nitrogen-enriched gas and outside air to the interior space (5) in order to change the composition of the air inside the storage area due to the breathing of the cargo inside the storage area. The concentration adjustment mode is an operating mode in which the oxygen concentration and carbon dioxide concentration in the interior space (5) are brought closer to the set values ​​without stopping the air pump (231). The system adjusts the composition of the air in the interior space (5) by switching between these operating modes.

[0165] (7-1) 8% Oxygen Concentration Mode As shown in Figure 10, in the 8% oxygen concentration mode, the air composition control device (100) repeatedly performs the first operation and the second operation alternately. Between the first operation and the second operation, the air composition control device (100) performs a pressure equalization operation. During the pressure equalization operation, the controller (110) opens the purge valve (251). This quickly equalizes the internal pressures of the first adsorption cylinder (234) and the second adsorption cylinder (235).

[0166] In the 8% oxygen concentration mode, the controller (110) keeps the gas discharge valve (272) closed and the gas supply valve (273) open at all times. As a result, low-oxygen gas is supplied to the interior space (5) from the start of the first and second operations. In each operation, the oxygen concentration in the nitrogen-enriched gas changes over time. Specifically, at the beginning of each operation, nitrogen-enriched gas with a relatively high oxygen concentration is generated because outside air remains in the adsorption cylinders (234, 235) and piping, and at the end of each operation, the pressure inside the adsorption cylinders (234, 235) decreases from the initial state, so more nitrogen components are desorbed, and nitrogen-enriched gas with a relatively high oxygen concentration is generated. In the 8% oxygen concentration mode, nitrogen-enriched gas is supplied to the interior space (5) from the start of the first and second operations, so the average oxygen concentration of the nitrogen-enriched gas over the entire duration of each operation is relatively high at 8%.

[0167] (7-2) 5% Oxygen Concentration Mode As shown in Figure 11, in the 5% oxygen concentration mode, the air composition control device (100) repeatedly performs the first operation and the second operation alternately, similar to the 8% oxygen concentration mode. Between the first operation and the second operation, the air composition control device (100) performs a pressure equalization operation.

[0168] In the 5% oxygen concentration mode, the controller (110) causes the air composition adjuster (100) to perform a gas discharge operation for a predetermined time (e.g., 4 seconds) from the start of the first operation. During the gas discharge operation, the controller (110) opens the gas discharge valve (272) and closes the gas supply valve (273). As described above, a nitrogen-enriched gas with a relatively high oxygen concentration is generated at the beginning of each operation. By performing the gas discharge operation, the nitrogen-enriched gas with a relatively high oxygen concentration is not supplied to the interior space (5) but is discharged to the exterior space (6) via the gas discharge pipe (276). After that, for the remainder of each operation, the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273). Thus, in the 5% oxygen concentration mode, nitrogen-enriched gas is discharged into the space outside the chamber (6) from the start of the first or second operation until a predetermined time has elapsed. As a result, the average oxygen concentration of the nitrogen-enriched gas over the entire duration of each operation is relatively low at 5%.

[0169] (7-3) Outside air intake mode In outside air intake mode, outside air from the outside space (6) is supplied directly to the inside space (5). In outside air intake mode, the controller (110) causes the air composition adjustment device (100) to perform the outside air intake operation described above. The oxygen concentration of the outside air is approximately 21%. The oxygen concentration of the inside air can be increased by using outside air intake mode.

[0170] (7-4) Breathing Mode In breathing mode, the controller (110) stops the air pump (231) and closes the gas discharge valve (272) and the measuring on / off valve (282). In breathing mode, nitrogen-enriched gas and outside air are not supplied to the interior space (5). As a result, the oxygen concentration in the interior air decreases and the carbon dioxide concentration increases as the cargo breathes.

[0171] (7-5) Concentration Adjustment Mode (Overview) In concentration adjustment mode, the controller (110) performs flow rate control and concentration control so that the oxygen concentration and carbon dioxide concentration in the air inside the chamber reach the set values. Here, the set values ​​include the oxygen concentration set value (SP_O2) and the carbon dioxide concentration set value (SP_CO2). The oxygen concentration set value (SP_O2) and the carbon dioxide concentration set value (SP_CO2) are input to the controller (110) by the user. That is, the user sets any set value to the controller (110) according to the type of produce and flowers to be loaded into the chamber space (5). Details of the concentration adjustment mode will be explained later.

[0172] (8) Preliminary operation The air composition adjustment device (90) of this embodiment performs a preliminary operation to estimate the respiration rate of the cargo (fruits and vegetables and flowers) before the concentration adjustment mode is executed. This is because the respiration rate of the cargo is greatly affected by the oxygen concentration and carbon dioxide in the storage space (5). As shown in Figure 12, the preliminary operation sequentially performs the measurement of the Cv value in step ST10, the estimation of the actual volume (Vs) in step ST11, and the estimation of the respiration rate in step ST12.

[0173] (8-1) Measurement of Cv value The Cv value is an indicator of the airtightness of the transport container (1). The smaller the Cv value, the higher the airtightness, and the less likely it is that the air inside the container (5) will leak out into the outside space (6). The larger the Cv value, the higher the airtightness, and the more likely it is that the air inside the container (5) will leak out into the outside space (6). For example, if the Cv value is 3.33 or less, the airtightness of the transport container (1) is relatively high, so the air inside can be sufficiently cooled by the transport refrigeration unit (10), and the composition of the air inside can be sufficiently adjusted by the air composition adjustment device (100). For example, if the Cv value is greater than 3.33 and less than 4.12, the air inside can be sufficiently cooled by the transport refrigeration unit (10), but it becomes difficult to adjust the composition of the air inside using the air composition adjustment device (100). For example, if the Cv value is 4.12 or higher, it becomes difficult to cool the internal air by the transport refrigeration unit (10) and to adjust the composition of the internal air by the air composition adjustment unit (100). Thus, the Cv value is useful for evaluating the airtightness performance of the transport container (1).

[0174] The controller (110) executes an airtightness measurement mode for measuring the Cv value of the transport container (1). The airtightness measurement mode of this embodiment includes a first airtightness measurement mode, a second airtightness measurement mode, and a third airtightness measurement mode. The first airtightness estimation mode is a mode that measures the Cv value using the depressurization method. The second airtightness estimation mode is a mode that measures the Cv value using the pressure increase method. The third airtightness estimation mode is a mode that measures the Cv value using the constant pressure method.

[0175] (8-1-1) First airtightness measurement mode (depressurization method) In the first airtightness measurement mode, the Cv value is automatically measured by the depressurization method. The controller (110) increases the internal pressure of the storage space (5) by operating the air pump (231) as a pressure adjustment unit. The controller (110) then determines the Cv value based on the rate of decrease of the internal pressure.

[0176] Specifically, as shown in Figure 13, in step ST11, the controller (110) operates the air pump (231) as a pressure regulating unit. In step ST11, the controller (110) closes the gas discharge valve (272), the measuring on / off valve (282), and the ventilation exhaust valve (151), and completely closes the supply air passage (41) and exhaust passage (42) of the ventilation device (40). In step ST11, the air composition adjustment device (100) opens the bypass valve (256) and the gas supply valve (273) in the same manner as the outside air introduction operation described above, and supplies outside air directly into the interior space (5) by the pressurizing pump (231a). However, as will be described in detail later, the air composition adjustment device (100) may close the bypass valve (256), open the gas supply valve (273), and supply the gas processed in the air processing unit (95) to the interior space (5) by the pressure reducing pump (231b), similar to the gas supply operation described above.

[0177] When air is introduced into the interior space (5), the internal pressure (Pi) increases in step ST12. In step ST13, the controller (110) stops the air pump (231) when the internal pressure (Pi) exceeds the first pressure (P1). The internal pressure (Pi) is determined by the differential pressure (ΔP) detected by the differential pressure sensor (170). The differential pressure (ΔP) is the difference between the internal pressure (Pi) and the external pressure (Po) (ΔP = Pi - Po). In this embodiment, the external pressure (Po) is set to atmospheric pressure (101.3 [kPa]). The controller (110) calculates the internal pressure (Pi) by adding the external pressure (Po) (atmospheric pressure) to the differential pressure (ΔP).

[0178] In step ST14, the controller (110) measures the first time (Δt1) until the internal pressure (Pi) decreases from the first pressure (P1) to the second pressure (P2). In the first airtightness measurement mode, the first pressure (P1) is greater than the second pressure (P2). For example, the first pressure (P1) is set to 300 [kPa] and the second pressure (P2) is set to 100 [kPa]. As shown in Figure 13, the controller (110) measures the first time (Δt1) from the first time point (t1) when the internal pressure (Pi) is the first pressure (P1) to the second time point (t2) when the internal pressure (Pi) is the second pressure (P2). If the airtightness of the transport container (1) is low, the rate of decrease in internal pressure (Pi) increases, so the first time (Δt1) becomes shorter. If the airtightness of the transport container (1) is high, the rate of decrease in internal pressure (Pi) will be low, and the first time (Δt1) will be longer. Thus, the rate of decrease in internal pressure, or more precisely, the time it takes for the internal pressure to decrease to a predetermined pressure, serves as an indicator of the airtightness of the transport container (1).

[0179] Next, in step ST15, the controller (110) obtains the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), and internal air temperature (Tr) when the internal pressure (Pi) reaches the second pressure (P2). Next, in step ST16, the controller (110) calculates the Cv value based on equations (1), (2), and (3) in Figure 13. Here, Qo is the outflow rate of gas flowing out of the internal space (5) at the first time (Δt1) [m³ 3 Qi is the flow rate of gas flowing into the storage space (5) at the first time (Δt1) [m 3The formula is [ / h]. G is the specific gravity of the gas (air) (= 1.0). Tr is the internal air temperature, i.e., the temperature detected by the internal temperature sensor (51). P1 is the internal pressure at the first time point (t1) (first pressure (P1)). P2 is the internal pressure at the second time point (t2) (second pressure (P2)). V1 is the volume of gas present in the internal space (5) at the first time point (t1). If no cargo is loaded into the internal space (5), V1 corresponds to the total volume when the internal space (5) is empty. V2 is the volume of gas in the internal space (5) at the second time point (t2). Δt1 is the first hour. Equation (1) is the basic formula for calculating the Cv value, equation (2) is a theoretical formula based on the equation of state in constant volume and isothermal change, and equation (3) is a theoretical formula for calculating V2.

[0180] In the depressurization method, the air pump (231) is stopped at the first time (Δt1), so Qi becomes zero. Therefore, Qo can be determined based on equations (2) and (3). By substituting Qo and other parameters into equation (1), the Cv value can be obtained. The controller (110) may determine the Cv value using a function that includes these equations, or it may determine the Cv value based on a data table that includes these relationships.

[0181] (8-1-2) Second airtightness measurement mode (pressure boosting method) In the second airtightness measurement mode, the Cv value is automatically measured by the pressure boosting method. The controller (110) increases the internal pressure of the interior space (5) by operating the air pump (231) as a pressure regulating unit. The controller (110) determines the Cv value based on the rate of increase of the internal pressure at this time.

[0182] Specifically, as shown in Figure 14, in step ST21, the controller (110) operates the air pump (231) which acts as a pressure regulator. The details of the control in step ST21 are the same as in step ST11.

[0183] In step ST22, the controller (110) measures the first time (Δt1) until the internal pressure (Pi) rises from the first pressure (P1) to the second pressure (P2). In the second airtightness measurement mode, the first pressure (P1) is lower than the second pressure (P2). For example, the first pressure (P1) is set to 100 [kPa] and the second pressure (P2) is set to 300 [kPa]. As shown in Figure 14, the controller (110) measures the first time (Δt1) from the first time point (t1) when the internal pressure (Pi) is the first pressure (P1) to the second time point (t2) when the internal pressure (Pi) is the second pressure (P2). If the airtightness of the transport container (1) is low, the rate of increase of the internal pressure (Pi) will be lower, and the first time (Δt1) will be longer. If the airtightness of the transport container (1) is high, the rate of increase in internal pressure (Pi) will be high, and the first time (Δt1) will be shorter. Thus, the rate of increase in internal pressure, or more precisely, the time it takes for the internal pressure to increase to a predetermined pressure, serves as an indicator of the airtightness of the transport container (1).

[0184] Next, in step ST23, the controller (110) acquires the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), internal air temperature (Tr), and inflow flow rate (Qi) when the internal pressure (Pi) reaches the second pressure (P2). In the pressure boosting method, the inflow flow rate (Qi) corresponds to the control flow rate of the air pump (231). More precisely, when air is transported into the internal space (5) by the pressurizing pump (231a), the inflow flow rate (Qi) is the control flow rate of the pressurizing pump (231a), and when air is transported by the depressurizing pump (231b), it is the control flow rate of the depressurizing pump (231b). Alternatively, a flow meter may be installed in the flow path supplying air to the internal space (5) to directly measure the inflow flow rate (Qi).

[0185] Next, in step ST24, the controller (110) calculates the Cv value based on equations (1), (2), and (3) in Figure 14. The details of the method for calculating the Cv value are the same as in the first airtightness measurement mode.

[0186] (8-1-3) Third Airtightness Measurement Mode (Constant Pressure Method) In the third airtightness measurement mode, the Cv value is automatically measured using the constant pressure method. The controller (110) operates the air pump (231) as a pressure regulating unit. When the air pump (231) reaches a steady state, the internal pressure of the storage space (5) becomes constant. The controller (110) uses parameters such as the internal pressure (Pi) at this time to determine the Cv value.

[0187] Specifically, as shown in Figure 15, in step ST31, the controller (110) operates the air pump (231) which acts as a pressure regulator. The details of the control in step ST31 are the same as in step ST11.

[0188] Next, in step ST32, the controller (110) determines whether the internal pressure (Pi) is constant. Here, "constant" means not only that the internal pressure (Pi) is maintained at a single value, but also that the internal pressure (Pi) is maintained within a predetermined range. In step ST32, the controller (110) determines whether the internal pressure (Pi) is within a predetermined range over a predetermined second time (Δt2). If the internal pressure (Pi) is constant over the predetermined second time (Δt2), the process proceeds to step ST33.

[0189] In step ST33, the controller (110) obtains the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), internal air temperature (Tr), and inflow rate (Qi) at the second time (Δt2). Here, these parameters may be values ​​at a specific point in the second time (Δt2) or may be average values ​​over the entire second time (Δt2). Next, in step ST34, the controller (110) calculates the Cv value based on equation (1) shown in Figure 14. When the internal pressure (Pi) is constant, the inflow rate (Qi) and outflow rate (Qo) are balanced. Therefore, the inflow rate (Qi) and outflow rate (Qo) at the second time (Δt2) are equal. Thus, the Cv value can be calculated by substituting the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), internal air temperature (Tr), and inflow rate (Qi) at the second time (Δt2) into equation (4). Here, the inflow rate (Qi) is the control flow rate of the pressurizing pump (231a) when air is transported into the storage space (5) by the pressurizing pump (231a), and the control flow rate of the depressurizing pump (231b) when air is transported by the depressurizing pump (231b). Alternatively, a flow meter may be installed in the flow path supplying air to the storage space (5) to directly measure the inflow rate (Qi).

[0190] (8-2) Estimation operation of the actual volume of the internal space After the Cv value has been measured, the controller (110) performs an estimation operation to estimate the actual volume (Vs) of the internal space (5). In the estimation operation of this embodiment, the controller (110) estimates the actual volume (Vs) of the internal space (5) based on the Cv value obtained in one of the airtightness measurement modes described above and a first index indicating the rate of change of the internal pressure (Pi). The estimation operation includes a first estimation operation based on the depressurization method and a second estimation operation based on the pressure increase method.

[0191] (8-2-1) First Estimation Operation The first estimation operation estimates the actual volume (Vs) of the internal space (5) based on a first indicator that shows the rate of change in the decrease of the internal pressure. For example, when cargo is loaded into the internal space (5) and the actual volume (Vs) decreases, the rate of decrease of the internal pressure (Pi) in the depressurization method increases. Conversely, for example, when the amount of cargo in the internal space (5) decreases and the actual volume (Vs) increases, the rate of decrease of the internal pressure (Pi) in the depressurization method decreases. Therefore, in the first estimation operation, the actual volume (Vs) is estimated using the first time (Δt1) in the depressurization method for the internal pressure (Pi) as the first indicator. The controller (110) performs the first estimation operation shown in Figure 16 after the airtightness measurement mode described above.

[0192] The processing in steps ST41 to ST45 of the first estimation operation is the same as steps ST11 to ST15 of the first airtightness measurement mode described above. That is, in steps ST41 to ST44, the controller (110) measures the first time (Δt1) until the internal pressure (Pi) decreases from the first pressure (P1) to the second pressure (P2). In step ST45, the controller (110) acquires the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), and internal air temperature (Tr).

[0193] Next, in step ST46, the controller (110) refers to the Cv value obtained in the airtightness measurement mode. This Cv value may be the value obtained in the first airtightness measurement mode, the second airtightness measurement mode, or the third airtightness measurement mode.

[0194] Next, in step ST47, the controller (110) uses the parameters obtained in steps ST44 to ST46 to determine the actual volume (Vs) based on equations (1), (2), and (3). In equation (1), the Cv value measured in airtightness measurement mode is used. Therefore, the outflow rate (Qo) can be determined from equation (1). By substituting this outflow rate (Qo) and the other parameters into equations (2) and (3), V1 can be determined. V1 is the gas volume of the storage space (5), that is, the actual volume (Vs) obtained by subtracting the volume of the cargo from the total volume of the storage space (5).

[0195] (8-2-2) Second Estimation Operation The second estimation operation estimates the actual volume (Vs) of the internal space (5) based on a first indicator that shows the rate of change in the increase of the internal pressure. For example, when cargo is loaded into the internal space (5) and the actual volume (Vs) decreases, the rate of increase of the internal pressure (Pi) in the pressure-boosting method increases. Conversely, for example, when the amount of cargo in the internal space (5) decreases and the actual volume (Vs) increases, the rate of increase of the internal pressure (Pi) in the pressure-boosting method decreases. Therefore, in the second estimation operation, the actual volume (Vs) is estimated using the first time (Δt1) in the pressure-boosting method for the internal pressure (Pi) as the first indicator. The controller (110) performs the second estimation operation shown in Figure 17 after the airtightness measurement mode described above.

[0196] The processing in steps ST51 to ST53 of the second estimation operation is the same as steps ST21 to ST23 of the second airtightness measurement mode described above. That is, in steps ST51 and ST52, the controller (110) measures the first time (Δt1) until the internal pressure (Pi) increases from the first pressure (P1) to the second pressure (P2). In step ST53, the controller (110) acquires the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), internal air temperature (Tr), and inflow flow rate (Qi).

[0197] Next, in step ST54, the controller (110) refers to the Cv value obtained in the airtightness measurement mode. This Cv value may be the value obtained in the first airtightness measurement mode, the second airtightness measurement mode, or the third airtightness measurement mode. Next, in step ST55, the controller (110) uses the parameters obtained in steps ST53 and ST54 to determine the actual volume (Vs) based on equations (1), (2), and (3) in the same manner as in the first estimation operation.

[0198] (8-3) Timing of airtightness measurement mode and estimated operation The transport container (1) is transported from the repair shop (terminal) to a cargo shipping site such as a farm, and then transported to the delivery site by a container ship or the like. The timing of the airtightness measurement mode during transport of such a transport container (1) will be explained below.

[0199] (8-3-1) First Example In the first example shown in Figure 27, a transport container (1) is transported to the delivery location via a repair workshop and cargo shipping point A. During period a, when the transport container (1) is traveling from the repair workshop to cargo shipping point A, the internal space (5) is empty. During period a, the Cv value can be determined using one of the first airtightness measurement mode, the second airtightness measurement mode, or the third airtightness measurement mode.

[0200] In the first and second airtightness measurement modes, in order to determine the Cv value from equations (2) and (3), the gas volume V1 at the first time point (t1), in other words, the actual volume (Vs) of the internal space (5), is required. During period a, the internal space (5) is empty, so the actual volume (Vs) of the internal space (5) corresponds to the total volume of the internal space (5). The total volume of the internal space (5) is determined by the specifications of the transport container (1). Therefore, during period a, the Cv value can be measured in the first and second airtightness measurement modes by referring to this total volume.

[0201] Specifically, the controller (110) stores the total volume of the storage space (5) that has been set in advance, or the total volume that the operator entered during period a. When the storage space (5) is empty, the controller (110) determines the Cv value based on the total volume of the storage space (5) and an index indicating the rate of pressure change in the storage space (5) using either the first airtightness measurement mode or the second airtightness measurement mode.

[0202] Furthermore, in period a, when measuring the Cv value using the third airtightness measurement mode, V1, i.e., the total volume of the internal space (5), is not required. This is because, as shown in Figure 15, the Cv value can be determined in the third airtightness measurement mode without using V1. When the internal space (5) is empty, the controller (110) uses the third airtightness measurement mode to determine the Cv value based on an index indicating the rate of pressure change in the internal space (5), without using the total volume of the internal space (5). Furthermore, as shown in Figure 27, in period a, the Cv value may also be determined using measuring equipment located in the repair workshop.

[0203] When the shipping container (1) arrives at the cargo shipping destination A, cargo A is loaded into the storage space (5). Therefore, during period b from the shipping destination A to the delivery location, cargo A is loaded into the storage space (5). In the storage space (5), the actual volume (Vs) is reduced by the volume of cargo A. However, during period b, the actual volume (Vs) of the storage space (5) can be estimated using the Cv value obtained in period a by the first or second estimation operation. In this way, when cargo is loaded into the storage space (5), the controller (110) estimates the actual volume (Vs) of the storage space (5) by the first or second estimation operation, based on the Cv value when the storage space (5) is empty and a first index indicating the rate of pressure change in the storage space.

[0204] (8-3-2) Second Example In the second example shown in Figure 28, a transport container (1) is transported to the cargo shipping point B, and then to the delivery location via the cargo shipping point C. During the period c from cargo shipping point B to cargo shipping point C, cargo B is loaded into the warehouse space (5). During period c, the controller (110) determines the Cv value using the third airtightness measurement mode.

[0205] During period c, cargo B is loaded into the storage space (5), so the actual volume (Vs) of the storage space (5) is smaller than the total volume of the storage space (5). For this reason, in the first airtightness measurement mode and the second airtightness measurement mode, the Cv value cannot be determined unless the actual volume (Vs) of the storage space (5) is known. In contrast, as shown in Figure 15, the third airtightness measurement mode can determine the Cv value without using V1, i.e., the actual volume (Vs). Therefore, the controller (110) can determine the Cv value even during period c using the third airtightness measurement mode.

[0206] When the transport container (1) arrives at the cargo shipping destination C, cargo C is loaded into the storage space (5). Therefore, during the period d from the cargo shipping destination C to the delivery location, cargo B and cargo C are loaded into the storage space (5). In the storage space (5), the actual volume (Vs) is reduced by the volume of cargo B and C. However, during period d, the actual volume (Vs) of the storage space (5) can be estimated using the Cv value obtained in the third airtightness measurement mode by the first or second estimation operation. In this way, when cargo is loaded into the storage space (5), the controller (110) estimates the actual volume (Vs) of the storage space (5) in the first or second estimation operation based on the Cv value obtained by the constant pressure method and an index indicating the rate of pressure change in the storage space.

[0207] (8-3-3) The specific timing controller (110) for the estimated operation can perform the estimated operation in conjunction with the operating mode of the air composition adjustment device (100).

[0208] As shown in Figure 18(a), the controller (110) performs the first estimation operation after switching from the outside air introduction operation (more precisely, the outside air introduction mode) to the breathing mode. In the outside air introduction operation, outside air is supplied to the interior space (5) by the pressurizing pump (231a), increasing the internal pressure (Pi). Subsequently, in breathing mode, the pressurizing pump (231a) stops. Therefore, in breathing mode, the first time (Δt1) until the internal pressure (Pi) decreases from the first pressure (P1) to the second pressure (P2) can be measured, and furthermore, the actual volume (Vs) can be determined.

[0209] As shown in Figure 18(b), the controller (110) performs the first estimation operation after switching from the gas supply operation (more precisely, the 5% oxygen mode or the oxygen outside air introduction mode) to the breathing mode. In the gas supply operation, nitrogen-enriched gas is supplied to the interior space (5) by the depressurization pump (231b), increasing the interior pressure (Pi). Subsequently, in breathing mode, the depressurization pump (231b) stops. Therefore, in breathing mode, the first time (Δt1) until the interior pressure (Pi) decreases from the first pressure (P1) to the second pressure (P2) can be measured, and furthermore, the actual volume (Vs) can be determined.

[0210] As shown in Figure 18(c), the controller (110) performs a second estimation operation after switching from the breathing mode described above to the outside air introduction operation (more precisely, the outside air introduction mode). At the start of the outside air introduction operation, outside air is supplied to the interior space (5) by the pressurizing pump (231a), increasing the internal pressure (Pi). Therefore, at the start of the outside air introduction operation, the first time (Δt1) until the internal pressure (Pi) increases from the first pressure (P1) to the second pressure (P2) can be measured, and furthermore, the actual volume (Vs) can be determined.

[0211] As shown in Figure 18(d), the controller (110) performs a second estimation operation after switching from the breathing mode described above to a gas supply operation (more precisely, the 5% oxygen mode or the oxygen outside air introduction mode). At the start of the gas supply operation, nitrogen-enriched gas is supplied to the interior space (5) by the depressurization pump (231b), increasing the interior pressure (Pi). Therefore, at the start of the gas supply operation, the first time (Δt1) until the interior pressure (Pi) increases from the first pressure (P1) to the second pressure (P2) can be measured, and furthermore, the actual volume (Vs) can be determined.

[0212] (8-5) The respiration rate estimation controller (110) performs a respiration rate estimation operation to determine the respiration rate of the cargo (more precisely, fruits, vegetables, flowers, etc.) based on the actual volume (Vs). The respiration rate estimation operation includes a first respiration rate estimation operation and a second respiration rate estimation operation. In the first respiration rate estimation operation, the controller (110) estimates the oxygen consumption rate (Ro) as the respiration rate of fruits, vegetables, and flowers. In the second respiration rate estimation operation, the controller (110) estimates the carbon dioxide production rate (Rc) as the respiration rate of fruits, vegetables, and flowers.

[0213] (8-5-1) First respiratory volume estimation operation In the first respiratory volume estimation operation shown in Figure 19, in step ST61, the controller (110) causes the gas supply operation to be performed. In step ST61, the controller (110) causes nitrogen-enriched gas with adjusted oxygen concentration to be supplied to the chamber space (5) by the gas supply operation. The gas supply operation may be in 8% oxygen concentration mode or in 5% oxygen concentration mode.

[0214] Next, in step ST62, the controller (110) measures the oxygen concentration (first oxygen concentration (Ca)) at the fifth time point (t5) in the interior space (5) using the oxygen sensor (161) and the oxygen concentration (second oxygen concentration (Cb)) at the sixth time point (t6) in the interior space (5).

[0215] Next, in step ST63, the controller (110) estimates the oxygen consumption rate (Ro) using equation (4) in Figure 19. Here, equation (4) is the theoretical formula for the second oxygen concentration (Cb) at the sixth time step (t6). In equation (4), Vs is the actual volume of the internal space (5), and corresponds to the volume of actual internal air present in the internal space (5). Δt3 is the time (third hour) between the fifth time step (t5) and the sixth time step (t6). Qi is the inflow rate of nitrogen-enriched gas supplied to the internal space (5). Co is the oxygen concentration of the nitrogen-enriched gas supplied to the internal space (5), which is 8% in the 8% oxygen concentration mode and 5% in the 5% oxygen concentration mode. By substituting each parameter into equation (4), the controller (110) can determine the oxygen consumption rate (Ro).

[0216] In step ST61, the controller (110) may perform an outside air introduction operation instead of a gas supply operation. In this case, the inflow rate (Qi) in equation (4) becomes the flow rate of outside air supplied to the interior space (5), and the supplied oxygen concentration (Co) in equation (4) becomes the oxygen concentration of the outside air (approximately 21%). If outside air flows into the interior space (5) from another route, the flow rate of this incoming air and the oxygen concentration of this air (21%) may be added to the numerator of equation (4), and the flow rate of this incoming air may be added to the denominator. The controller (110) can estimate this air flow rate based on the Cv value or the first index.

[0217] (8-5-2) Second respiratory volume estimation operation In the second respiratory volume estimation operation shown in Figure 20, in step ST71, the controller (110) causes the gas supply operation to be performed. In step ST71, the controller (110) causes nitrogen-enriched gas with adjusted oxygen concentration to be supplied to the chamber space (5) by the gas supply operation. The gas supply operation may be in 8% oxygen concentration mode or in 5% oxygen concentration mode.

[0218] Next, in step ST72, the controller (110) measures the carbon dioxide concentration (first carbon dioxide concentration (Cc)) at the seventh time point (t7) in the interior space (5) and the carbon dioxide concentration (second carbon dioxide concentration (Cd)) at the eighth time point (t8) in the interior space (5) using a carbon dioxide sensor (162).

[0219] Next, in step ST73, the controller (110) estimates the carbon dioxide generation rate (Rc) using equation (5) in Figure 20. Here, equation (5) is the theoretical formula for the second carbon dioxide concentration (Cd) at the eighth time point (t8). In equation (5), Δt4 is the time (fourth hour) between the seventh time point (t7) and the eighth time point (t8). In the numerator of equation (5), the carbon dioxide supplied to the interior space (5) by the supply of nitrogen-enriched gas is ignored because the carbon dioxide concentration is extremely low, approximately 300 ppm. By substituting each parameter into equation (5), the controller (110) can determine the carbon dioxide generation rate (Rc).

[0220] In step ST71, the controller (110) may perform an outside air introduction operation instead of a gas supply operation. In this case as well, in equation (4), carbon dioxide in the outside air supplied to the interior space (5) can be ignored. If outside air flows into the interior space (5) from another route, the flow rate of this incoming air may be added to the denominator of equation (5). The controller (110) can estimate this air flow rate based on the Cv value or the first index.

[0221] (9) Details of the concentration adjustment mode Next, the details of the concentration adjustment mode will be explained with reference to Figures 21 to 24. In the concentration adjustment mode, the controller (110) coordinately performs flow rate control, which adjusts the flow rate of the first air supplied from the supply path (S) to the interior space (5), and concentration control, which adjusts the composition of this first air. In flow rate control, the controller (110) adjusts the flow rate of the first air (hereinafter also called the first flow rate (Q1)) while the air pump (231) is operating so that the carbon dioxide concentration of the components in the interior air reaches the set carbon dioxide concentration (SP2). In concentration control, the controller (110) adjusts the oxygen concentration of the first air (hereinafter also called the first oxygen concentration (C1)) while the air pump (231) is operating so that the oxygen concentration of the components in the interior air reaches the set oxygen concentration (SP1).

[0222] (9-1) Basic flow chart 21 is the basic flow of the concentration control mode. When a command to operate the concentration control mode is input to the controller (110) in response to user operation (YES in step ST81), in step ST82 the controller (110) starts the concentration control mode.

[0223] In step ST83, the controller (110) calculates the target flow rate (Qt) to satisfy the set carbon dioxide concentration (SP2) based on equation (6) in Figure 21. Here, Rc is the carbon dioxide generation rate of the cargo obtained in the second respiration volume estimation operation, and Qt is the target flow rate of the first air. By controlling the first flow rate (Q1) of the first air to the target flow rate (Qt), the carbon dioxide concentration in the storage space (5) converges to the set carbon dioxide concentration (SP2). Note that equation (6) ignores the carbon dioxide concentration contained in the first air. This is because the carbon dioxide concentration contained in the first air is extremely low, for example, about 300 ppm.

[0224] In step ST84, the controller (110) calculates the target oxygen concentration (C1) to satisfy the set oxygen concentration (SP1) based on equations (6) and (7) in Figure 21. Here, Ro is the oxygen consumption rate of the cargo obtained in the first respiration volume estimation operation, and Ct is the target oxygen concentration of the first air. By controlling the oxygen concentration of the first air (C1) to the target concentration (Ct), the oxygen concentration of the air inside the warehouse converges to the set oxygen concentration (SP1).

[0225] Next, the controller (110) coordinately performs the flow rate control in step ST85 and the concentration control in step ST86. When a command to terminate the concentration adjustment mode is input to the controller (110) in response to user operation (YES in step ST87), the controller (110) terminates the concentration adjustment mode in step ST88.

[0226] (9-2) Flow Rate Control The flow rate control in this embodiment includes a first flow rate control and a second flow rate control. The first flow rate control is a control mode that brings the first flow rate (Q1) of the first air closer to the target flow rate (Qt) determined in step ST83. In the first flow rate control, the first flow rate (Q1) of the first air is set to the target flow rate (Qt) that satisfies the set carbon dioxide concentration (SP2). Therefore, in the first flow rate control, the carbon dioxide concentration of the air inside the chamber can be brought closer to the set value quickly. The second flow rate control increases or decreases the first flow rate (Q1) so that the carbon dioxide concentration of the air inside the chamber approaches the set carbon dioxide concentration (SP2). In the second flow rate control, the carbon dioxide concentration of the air inside the chamber can be brought closer to the set value with high accuracy. The controller (110) switches between the first flow rate control and the second flow rate control based on a first condition. The first condition is a condition that indicates that the carbon dioxide concentration in the air inside the chamber is close to the set value.

[0227] Specifically, as shown in Figure 22, in step ST101, the controller (110) determines whether or not the first condition is met. The first condition in this embodiment is whether or not the carbon dioxide concentration in the internal space (5) (hereinafter also referred to as the internal carbon dioxide concentration (Cs2)) is within a predetermined first range that includes a set value. The first range is within the range of the set carbon dioxide concentration (SP2) ± α%. More precisely, the first range is within the range of SP2 - SP2 × α% or more and SP2 + SP_CO2 × α% or less. α is set to, for example, 0.1. The internal carbon dioxide concentration (Cs2) is detected by the carbon dioxide sensor (162).

[0228] In step ST101, if the first condition is not met, that is, if the carbon dioxide concentration (Cs2) inside the chamber is not within the first range, the controller (110) performs the first flow rate control in step ST102. In the first flow rate control, the controller (110) controls the first flow rate (Q1) of the first air to the target flow rate (Qt). As a result, the carbon dioxide concentration (Cs2) inside the chamber can be quickly brought closer to the set carbon dioxide concentration (SP2). Details of the specific method for adjusting the flow rate of the first air will be described later.

[0229] In step ST101, if the first condition is met, that is, if the carbon dioxide concentration (Cs2) inside the chamber is within the first range, the controller (110) performs second flow rate control. In the second flow rate control, the controller (110) adjusts the first flow rate (Q1) of the first air so that the carbon dioxide concentration (Cs2) inside the chamber becomes the set carbon dioxide concentration (SP2). Specifically, in step ST103, if the carbon dioxide concentration (Cs2) inside the chamber is greater than the set carbon dioxide concentration (SP2), the controller (110) increases the current first flow rate (Q1) by a predetermined amount in step ST105. As the first flow rate (Q1) increases, the carbon dioxide concentration (Cs2) inside the chamber decreases. In step ST104, if the carbon dioxide concentration (Cs2) inside the chamber is less than the set carbon dioxide concentration (SP2), the controller (110) decreases the current first flow rate (Q1) by a predetermined amount in step ST106. As the first flow rate (Q1) decreases, the carbon dioxide concentration (Cs2) inside the warehouse increases due to the respiration of the cargo.

[0230] Thus, in this embodiment, when the difference between the carbon dioxide concentration inside the chamber (Cs2) and the set carbon dioxide concentration (SP2) is large, the first flow rate control is executed, and when the difference between the carbon dioxide concentration inside the chamber (Cs2) and the set carbon dioxide concentration (SP2) is small, the second flow rate control is executed. As a result, the carbon dioxide concentration inside the chamber (Cs2) can be quickly and accurately brought to the set carbon dioxide concentration (SP2).

[0231] (9-3) Concentration Control The concentration control in this embodiment includes a first concentration control and a second concentration control. The first concentration control is a control mode that brings the oxygen concentration (C1) of the first air closer to the target concentration (Ct) determined in step ST84. In the first concentration control, the oxygen concentration (C1) of the first air is set to the target concentration (Ct) that satisfies the set oxygen concentration (SP1). Therefore, in the first concentration control, the oxygen concentration of the air inside the chamber can be quickly brought closer to the set value. In the second concentration control, the oxygen concentration (C1) of the first air is increased or decreased so that the oxygen concentration of the air inside the chamber approaches the set oxygen concentration (SP1). In the second concentration control, the oxygen concentration of the air inside the chamber can be brought closer to the set value with high accuracy. The controller (110) switches between the first concentration control and the second concentration control based on a second condition. The second condition is a condition that indicates that the oxygen concentration in the air inside the chamber is close to the set value.

[0232] Specifically, as shown in Figure 23, in step ST111, the controller (110) determines whether the second condition is met. The second condition in this embodiment is whether the oxygen concentration in the internal space (5) (hereinafter also referred to as internal oxygen concentration (Cs1)) is within a predetermined second range that includes a set value. The second range is within the range of set oxygen concentration (SP1) ± β%. More precisely, the second range is within the range of SP1 - SP1 × β% or more and SP1 + SP1 × β% or less. β is set to, for example, 0.1. The internal oxygen concentration (Cs1) is detected by the oxygen sensor (161).

[0233] If the second condition is not met in step ST111, that is, if the oxygen concentration inside the chamber (Cs1) is not within the second range, the controller (110) performs the first concentration control in step ST112. In the first concentration control, the controller (110) controls the oxygen concentration of the first air (C1) to the target concentration (Ct). As a result, the oxygen concentration inside the chamber (Cs1) can be quickly brought closer to the set oxygen concentration (SP1). Details of the specific method for adjusting the oxygen concentration of the first air (C1) will be described later.

[0234] In step ST113, if the second condition is met, that is, if the oxygen concentration inside the chamber (Cs1) is within the second range, the controller (110) performs the second concentration control. In the second concentration control, the controller (110) adjusts the oxygen concentration (C1) of the first air so that the oxygen concentration inside the chamber (Cs1) becomes the set oxygen concentration (SP1). Specifically, in step ST113, if the oxygen concentration inside the chamber (Cs1) is greater than the set oxygen concentration (SP1), in step ST115, the controller (110) decreases the current oxygen concentration (C1) by a predetermined amount. As a result, the oxygen concentration inside the chamber (Cs1) decreases and approaches the set oxygen concentration (SP1). In step ST114, if the oxygen concentration inside the chamber (Cs1) is less than the set oxygen concentration (SP1), in step ST116, the controller (110) increases the current oxygen concentration (C1) of the first air by a predetermined amount. As a result, the oxygen concentration inside the chamber (Cs1) increases and approaches the set oxygen concentration (SP1).

[0235] Thus, in this embodiment, when the oxygen concentration inside the chamber (Cs1) is far from the set oxygen concentration (SP1), a first concentration control is performed, and when the oxygen concentration inside the chamber (Cs1) is close to the set oxygen concentration (SP1), a second concentration control is performed. As a result, the oxygen concentration inside the chamber (Cs1) can be quickly and accurately converged to the set oxygen concentration (SP1).

[0236] (9-4) Specific Examples of Flow Rate Control In this embodiment, the controller (110) controls the air pump (231) to adjust the flow rate of the first air supplied from the supply path (S) to the storage space (5) (first flow rate (Q1)). Specifically, the controller (110) controls the rotational speed of the air pump (231), specifically the operating frequency of the motor. As a result, in the first flow rate control, the first flow rate (Q1) can be controlled to a target flow rate (Qt). In the second flow rate control, the first flow rate (Q1) can be increased or decreased by a predetermined amount.

[0237] Furthermore, in order to improve the controllability of the first flow rate (Q1), the first flow rate (Q1) may be measured. To measure the first flow rate (Q1), a flow meter may be installed in the supply line (S), specifically in the gas supply pipe (275). The controller (110) performs feedback control of the first flow rate (Q1) based on the value detected by the flow meter.

[0238] Alternatively, the controller (110) can estimate the first flow rate (Q1) based on the Cv value. Specifically, when the internal pressure (Pi) is constant during the operation of the air pump (231), the inflow flow rate (Qi) of the first air can be determined using equation (1) by the constant pressure method shown in Figure 15. In this case, the controller (110) can estimate the inflow flow rate (Qi), i.e., the first flow rate (Q1), using equation (1) with the previously determined Cv value, internal air temperature (Tr), differential pressure (ΔP), internal pressure (Pi), and external pressure (Po).

[0239] (9-5) Specific Examples of Concentration Control In the concentration control described above, the controller (110) adjusts the oxygen concentration (C1) of the first air. The specific method of concentration control will be explained below. The controller (110) adjusts the oxygen concentration (C1) of the first air by controlling the timing of opening and closing the gas discharge valve (272) for discharging the processed gas (nitrogen-enriched gas) processed in the air processing unit (95) to the space outside the chamber (6).

[0240] Figure 24 is a timing chart showing the oxygen concentration of the processed gas immediately after switching between the first and second operations described above, and the timing of opening and closing of the gas discharge valve (272) and gas supply valve (273). In Figure 24, ts indicates the time of switching between the first and second operations. At the beginning of the first and second operations, the oxygen concentration of the processed gas is high. This is because, as described above, at the beginning of each operation, outside air remains in the adsorption cylinders (234, 235) and piping, etc., so a nitrogen-enriched gas with a relatively high oxygen concentration is generated. On the other hand, at the end of the first and second operations, the oxygen concentration of the processed gas decreases rapidly. This is because the pressure inside the adsorption cylinders (234, 235) decreases from the initial stage, causing more nitrogen components to be desorbed and the oxygen concentration to decrease. In this embodiment, the oxygen concentration (C1) of the first air is adjusted by utilizing the change in oxygen concentration during the period of each operation.

[0241] In the first control example shown in Figure 24(a), the oxygen concentration (C1) of the first air is adjusted to a low concentration. In this example, the controller (110) opens the gas discharge valve (272) and closes the gas supply valve (273) during period TA, when the oxygen concentration of the process gas is high. As a result, the process gas with a high oxygen concentration is discharged to the space outside the chamber (6). During period TB, when the oxygen concentration of the process gas is low, the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273). As a result, the process gas with a low oxygen concentration is supplied to the space inside the chamber (5) as the first air. Thus, in the first control example, the process gas with a high oxygen concentration is discharged to the space outside the chamber (6) during period TA, and the process gas with a low oxygen concentration is supplied to the space inside the chamber (5) during period TB. This adjusts the oxygen concentration (C1) of the first air to a low concentration on average over the entire duration of each operation.

[0242] In the second control example shown in Figure 24(b), the oxygen concentration (C1) of the first air is adjusted to a medium concentration. In this example, the controller (110) opens the gas discharge valve (272) and closes the gas supply valve (273) during a portion of period TA (for example, the first half). As a result, during the first half of period TA, a process gas with a high oxygen concentration is discharged to the outside space (6). During the remainder of period TA (the second half), the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273). As a result, during the remainder of period TA, a process gas with a high oxygen concentration is supplied to the inside space (5) as the first air. During period TB, the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273). As a result, during period TB, a process gas with a low oxygen concentration is supplied to the inside space (5) as the first air. In this second control example, during a portion of period TA, a process gas with a high oxygen concentration is discharged to the space outside the chamber (6), during the remainder of period TA, a process gas with a high oxygen concentration is supplied to the space inside the chamber (5), and during period TB, a process gas with a low oxygen concentration is supplied to the space inside the chamber (5). As a result, the oxygen concentration of the first air (C1) is adjusted to a medium concentration as an average over the entire period of each operation.

[0243] In the third control example shown in Figure 24(c), the oxygen concentration (C1) of the first air is adjusted to a high concentration. In this example, the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273) during period TA. As a result, during period TA, a process gas with a high oxygen concentration is supplied to the interior space (5) as the first air. During period TB, the controller (110) closes the gas discharge valve (272) and opens the gas supply valve (273). As a result, a process gas with a low oxygen concentration is discharged to the exterior space (6). Thus, in the third control example, during period TA, a process gas with a high oxygen concentration is supplied to the interior space (5), and during period TB, a process gas with a low oxygen concentration is discharged to the exterior space (6). This adjusts the oxygen concentration (C1) of the first air to a high concentration on average over the entire duration of each operation.

[0244] As described above, the controller (110) switches the timing of opening and closing the gas discharge valve (272) in at least three or more patterns. In each control example, the controller (110) may also keep the gas supply valve (273) open at all times during each operation. In this case, by opening the gas discharge valve (272), some of the processed gas is discharged to the space outside the chamber (6), and the remaining processed gas is supplied to the space inside the chamber (5).

[0245] (10) Features of the Embodiment (10-1) The controller (110) performs flow rate control to adjust the flow rate of the first air so that the concentration of components in the air inside the storage chamber reaches a set value while the air pump (231), which is the air transport unit, is in operation. Specifically, in the concentration adjustment mode, the controller (110) adjusts the first flow rate (Q1) of the first air so that the carbon dioxide concentration in the air inside the storage chamber reaches a set carbon dioxide concentration (SP2). For this reason, the carbon dioxide concentration in the air inside the storage chamber can be brought to the set carbon dioxide concentration (SP2) without switching modes between multiple modes, such as a 5% oxygen concentration mode, an 8% oxygen concentration mode, an outside air introduction mode, and a breathing mode. Therefore, the range of change in the carbon dioxide concentration in the air inside the storage chamber can be reduced when switching modes, so that the freshness of fruits, vegetables and flowers can be maintained.

[0246] The controller (110) performs concentration control while the air pump (231), which is the air transport unit, is in operation, adjusting the concentration of the components in the first air so that the concentration of the components in the air inside the storage unit reaches a set value. Specifically, in concentration adjustment mode, the controller (110) adjusts the oxygen concentration (C1) of the first air so that the oxygen concentration in the air inside the storage unit reaches the set oxygen concentration (SP1). Therefore, the oxygen concentration of the air inside the storage unit can be brought to the set oxygen concentration (SP1) without switching modes. Consequently, the range of change in the oxygen concentration of the air inside the storage unit can be reduced when switching modes, thus maintaining the freshness of fruits, vegetables, and flowers.

[0247] In concentration control mode, the air pump (231) is not stopped, for example, as in breathing mode. In other words, in concentration control mode, the controller (110) keeps the air pump (231) running at all times. Therefore, the operation of the air pump (231) can maintain positive pressure in the storage space (5). Consequently, the intrusion of outside air into the storage space (5) can be suppressed. As a result, changes in the carbon dioxide concentration and oxygen concentration in the storage space (5) caused by the intrusion of outside air can be suppressed. In addition, an increase in the cooling load of the transport refrigeration unit (10) caused by the intrusion of outside air can be suppressed.

[0248] (10-2) In flow control, the controller (110) adjusts the first flow rate (Q1) of the first air by controlling a variable flow rate air pump (231). Therefore, the first flow rate (Q1) can be easily and precisely adjusted.

[0249] The controller (110) adjusts the oxygen concentration (C1) of the first air by adjusting the opening and closing timing of the gas discharge valve (272) in concentration control. Therefore, the oxygen concentration (C1) of the first air can be easily adjusted without using other oxygen sources.

[0250] (10-3) The controller (110) determines the target flow rate to bring the carbon dioxide concentration in the air inside the chamber to the set oxygen concentration (SP1). In the first flow rate control, the controller (110) adjusts the first flow rate of the first air to the target flow rate (Qt). This control allows the carbon dioxide concentration in the chamber space (5) to quickly converge to the set carbon dioxide concentration (SP2). Since the carbon dioxide concentration in the first air is extremely low, the target flow rate (Qt) of the first air can be determined without considering the carbon dioxide concentration in the first air.

[0251] The controller (110) estimates the carbon dioxide generation rate (Rc) of fruits, vegetables, or flowers in the storage space (5) and determines the target flow rate (Qt) based on the estimated carbon dioxide generation rate (Rc). By determining the target flow rate (Qt) while considering the carbon dioxide generation rate (Rc) of fruits, vegetables, or flowers, the carbon dioxide concentration in the storage space (5) can be maintained at a more appropriate value.

[0252] The controller (110) estimates the carbon dioxide generation rate (Rc) based on the actual volume (Vs) of the internal space (5) and the carbon dioxide concentration in the internal air. Therefore, the carbon dioxide generation rate (Rc) can be accurately estimated.

[0253] (10-4) The controller (110) determines the target concentration (Ct) to bring the oxygen concentration in the air inside the chamber to the set oxygen concentration (SP1). In concentration control, the controller (110) adjusts the oxygen concentration of the first air to the target concentration (Ct). This control allows the oxygen concentration in the chamber space (5) to quickly converge to the set oxygen concentration (SP1).

[0254] The controller (110) estimates the oxygen consumption rate (Ro) of fruits, vegetables, or flowers in the storage space (5) and determines the target flow rate (Qt) based on the estimated oxygen consumption rate (Ro). This control allows the oxygen concentration in the storage space (5) to quickly converge to the set oxygen concentration (SP1).

[0255] The controller (110) estimates the oxygen consumption rate (Ro) of fruits, vegetables, or flowers in the storage space (5) and determines the target flow rate (Qt) based on the estimated oxygen consumption rate (Ro). By determining the target flow rate (Qt) while considering the oxygen consumption rate (Ro) of fruits, vegetables, or flowers, the oxygen concentration in the storage space (5) can be maintained at a more appropriate value.

[0256] The controller (110) estimates the oxygen consumption rate (Ro) based on the actual volume (Vs) of the interior space (5) and the oxygen concentration in the air inside the interior. Therefore, the oxygen consumption rate can be accurately estimated.

[0257] (10-5) The air composition adjustment device (90) includes an air pump (231) as a pressure adjustment unit that changes the pressure in the internal space (5), and a differential pressure sensor (170) as a pressure detection unit that detects the internal pressure (Pi) of the internal space (5). When the internal pressure (Pi) changes, the controller (110) estimates the actual volume (Vs) based on a first index that indicates the rate of change of the internal pressure (Pi). Therefore, the actual volume (Vs) can be automatically estimated using the air pump (231) used for transporting the first air and the differential pressure sensor (170) used for managing the transport container (1).

[0258] In particular, the controller (110) estimates the actual volume (Vs) using the Cv value. Therefore, the actual volume (Vs) can be estimated with high accuracy. Furthermore, the Cv value can also be used for the management and evaluation of the transport container (1).

[0259] (10-6) The controller (110) performs a first flow rate control to adjust the flow rate of the first air to a target flow rate (Qt), and a second flow rate control to adjust the flow rate of the first air so that the carbon dioxide concentration (Cs2) inside the chamber detected by the carbon dioxide concentration sensors (161, 162) becomes a set carbon dioxide concentration (SP2). The first flow rate control can quickly bring the carbon dioxide concentration of the air inside the chamber closer to the set carbon dioxide concentration (SP2), and the second flow rate control can bring the carbon dioxide concentration of the air inside the chamber closer to the set carbon dioxide concentration (SP2) with high accuracy.

[0260] The controller (110) executes a first flow rate control when the first condition, which indicates that the carbon dioxide concentration in the air inside the chamber is close to the set carbon dioxide concentration (SP2), is not met. The controller (110) executes a second flow rate control when the first condition is met. This allows the carbon dioxide concentration in the air inside the chamber to converge to the set carbon dioxide concentration (SP2) quickly and accurately.

[0261] (10-7) The controller (110) performs a first concentration control, which adjusts the oxygen concentration (C1) of the first air to a target concentration (Ct), and a second concentration control, which adjusts the oxygen concentration (C1) of the first air so that the oxygen concentration (Cs1) inside the chamber detected by the oxygen concentration sensors (161, 162) becomes the set oxygen concentration (SP1). The first concentration control can quickly bring the carbon dioxide concentration of the inside air closer to the set carbon dioxide concentration (SP2), and the second concentration control can accurately bring the oxygen concentration of the inside air closer to the set oxygen concentration (SP1).

[0262] The controller (110) executes the first concentration control when the second condition, which indicates that the oxygen concentration (C1) in the air inside the chamber is close to the set oxygen concentration (SP1), is not met. The controller (110) executes the second concentration control when the second condition is met. This allows the oxygen concentration in the air inside the chamber to converge to the set oxygen concentration (SP1) quickly and accurately.

[0263] (10-8) The controller (110) performs a first estimation operation to estimate the actual volume (Vs) of the internal space (5) based on a first indicator showing the rate of increase of the internal pressure (Pi). Thus, the actual volume (Vs) can be estimated when the internal pressure is increased by the air pump (231).

[0264] The controller (110) performs a second estimation operation to estimate the actual volume (Vs) of the internal space (5) based on a first indicator showing the rate of decrease in the internal pressure (Pi). Thus, the actual volume (Vs) can be estimated when the internal pressure is increased by the air pump (231) and then decreased.

[0265] (10-9) In the estimation operation, the controller (110) estimates the actual volume (Vs) based on the airtightness index of the transport container (1) and the first index. This allows the controller to estimate the actual volume (Vs) while individually considering air leakage from the transport container (1) even when there is variation in the airtightness of the transport container (1). Therefore, the actual volume (Vs) of the internal space (5) can be estimated with high accuracy.

[0266] Specifically, the controller (110) performs a first airtightness measurement mode to determine the airtightness index based on the internal pressure (Pi), the external pressure (Po) of the external space (6), and an index indicating the rate of decrease in internal pressure (Pi) when the internal pressure (Pi) decreases. This is because the external pressure (Po), internal pressure (Pi), and the rate of decrease in internal pressure are parameters that affect the airtightness index of the transport container (1). The first airtightness measurement mode has the advantage that the inflow flow rate (Qi) is zero, so there is no need to measure the inflow flow rate (Qi).

[0267] The controller (110) executes a second airtightness measurement mode to determine the airtightness index based on the internal pressure (Pi), the external pressure (Po) of the external space (6), and an index indicating the rate of increase of the internal pressure (Pi) when the internal pressure (Pi) increases or changes. This is because the external pressure (Po), internal pressure (Pi), and the rate of increase of the internal pressure are parameters that affect the airtightness index of the transport container (1). The second airtightness measurement mode determines the rate of increase of the internal pressure (Pi) associated with the operation of the air pump (231), and therefore has the advantage of shorter measurement time compared to the first airtightness measurement mode.

[0268] The controller (110) executes the first airtightness measurement mode or the second airtightness measurement mode when the storage space (5) is empty. The first airtightness measurement mode and the second airtightness measurement mode require V1, that is, the actual volume (Vs), in equations (2) and (3), and when the storage space (5) is empty, the actual volume (Vs) can be considered as the total volume of the storage space (5).

[0269] (10-10) The pressure adjustment unit (231) is an air transport unit that supplies air to the interior space (5). The controller (110) performs a third airtightness measurement mode to determine the airtightness index based on the interior pressure (Pi), the external pressure (Po) of the external space (6), and the inflow rate of air supplied to the interior space (5) during a period when the interior pressure (Pi) is constant while the air pump (231) is in operation. This is because if the interior pressure (Pi) is constant, these parameters will affect the airtightness index.

[0270] The controller (110) executes the third airtightness measurement mode when there is cargo in the storage space (5). The third airtightness measurement mode is an airtightness index measured when the storage pressure (Pi) is constant and is not affected by the actual volume of the storage space (5). Therefore, even when there is cargo in the storage space (5), the Cv value can be accurately estimated without using the actual volume (Vs).

[0271] (10-11) In the estimation operation, the controller (110) estimates the actual volume (Vs) based on the external pressure (Po) of the external space (6) and the first indicator. Therefore, even if the airtightness of the transport container (1) is insufficient and air leaks between the external space (6) and the internal space (5), the actual volume (Vs) can be estimated while individually considering the air leakage from the transport container (1).

[0272] (10-12) The pressure detection unit includes a differential pressure sensor (170) that detects the differential pressure between the outside air and the inside air. The controller (110) determines the inside pressure (Pi) from the differential pressure (ΔP) of the differential pressure sensor (170) and atmospheric pressure (i.e., outside pressure). This simplifies the configuration of the pressure detection unit.

[0273] The pressure regulating unit is comprised of an air pump (231). This simplifies the configuration of the air composition regulating device (90).

[0274] (11) Modifications of the Embodiments The embodiments described above may also be configured in the following modified form. In principle, the differences from the above embodiments will be explained below.

[0275] (11-1) Modification 1 The air composition adjustment device (90) of Modification 1 shown in Figure 25 has a gas storage tank (290) and an auxiliary pump (291). The gas storage tank (290) and the auxiliary pump (291) are installed in the supply passage (S), specifically in the gas supply pipe (275). The gas storage tank (290) stores nitrogen-enriched gas (low-concentration oxygen gas) after treatment in the air processing unit (95). The auxiliary pump (291) transports the nitrogen-enriched gas stored in the gas storage tank (290) and supplies it to the interior space (5). The auxiliary pump (291) is a variable flow rate pump. The air pump (231) in Modification 1 is a fixed flow rate type. The gas storage tank (290) and the auxiliary pump (291) are located outside the unit case (201).

[0276] In the modified example 1, the processed gas, whose composition has been adjusted in the air processing unit (95) by the air pump (231), flows through the gas supply passage (S). At this time, the controller (110) adjusts the first flow rate (Q1) of the first air by controlling the auxiliary pump (291) in flow rate control. The gas storage tank (290) and the auxiliary pump (291) may be provided in a flow path provided in parallel with the gas supply pipe (275) in the supply passage (S).

[0277] (11-2) Modification 2 The air composition adjustment device (90) of Modification 2 has an outside air introduction unit that introduces outside air into the interior space (5) as second air without going through the supply passage (S). The outside air introduction unit of Modification 2 is a ventilation device (40). The ventilation device (40) supplies outside air to the interior space (5) through the supply air communication port (41a). The ventilation device (40) has an interior fan (35) that constitutes the supply air fan. In flow rate control, the controller (110) adjusts the flow rate of the first air introduced into the interior space (5) from the supply passage (S) and the flow rate of the second air supplied to the interior space (5) by the ventilation device (40) so that the components in the interior air (e.g., carbon dioxide concentration) become set values. The outside air introduction unit may be an air pump that supplies outside air to the interior space (5) via a flow path different from the supply passage (S).

[0278] (11-3) Modification 3 In Modification 3, the air composition adjustment device (90) has a bypass valve (256) of the bypass connecting pipe (255) that is configured as a flow control valve. The bypass valve (256) is an electrically operated valve whose opening degree can be adjusted. As shown in Figure 26, in concentration control of Modification 3, the processed gas (nitrogen-enriched gas) processed in the air processing unit (95) and the outside air flowing through the bypass connecting pipe (255) are mixed in the gas supply pipe (275), which is the second flow path. The mixing ratio of the processed gas and the outside air corresponds to the opening degree of the bypass valve (256). In concentration control, the controller (110) adjusts the opening degree of the bypass valve (256), or in other words, the mixing ratio, so that the oxygen concentration of the air inside the chamber becomes a set value. In flow control, the controller (110) may also adjust the flow rate of the first air by adjusting the opening degree of the bypass valve (256).

[0279] (11-4) Modification 4 The controller (110) may consider the amount of outside air introduced into the interior space (5) from the exterior space (6) in equations (6) and (7) of Figure 21 for estimating the respiration rate. In this case, in equation (6), the inflow rate of outside air is added to the denominator. In equation (7), the product of the inflow rate of outside air and the oxygen concentration (21%) is added to the numerator, and the inflow rate of outside air is added to the denominator. The inflow rate of outside air can be determined, for example, by subtracting the flow rate of the first air (Q1), which is determined by the control value of the air pump (231), from the inflow rate (Qi), which is determined by equation (1), using the previously determined Cv value, interior air temperature (Tr), differential pressure (ΔP), interior pressure (Pi), and exterior pressure (Po). The controller (110) performs the control described above if the internal pressure (Pi) detected by the differential pressure sensor (170), which is a pressure detection unit, is positive, and performs the control of the modified example 4 if the internal pressure (Pi) is negative.

[0280] (11-5) Modification 5 In Modification 5, the first condition for switching between the first flow rate control and the second flow rate control differs from that of the embodiment. The first condition in Modification 5 is that the elapsed time from the start of operation in concentration adjustment mode is longer than a predetermined time. Specifically, the controller (110) executes the first flow rate control when the concentration adjustment mode starts. This is because the carbon dioxide concentration in the air inside the chamber is far from the set value when the concentration adjustment mode starts. After that, when the elapsed time becomes longer than the predetermined time, the first condition is met, and the controller (110) executes the second flow rate control.

[0281] In Modification 5, the second condition for switching between the first concentration control and the second concentration control differs from that of the embodiment. The second condition in Modification 5 is that the elapsed time from the start of operation in concentration adjustment mode is longer than a predetermined time. Specifically, the controller (110) executes the first concentration control at the start of concentration adjustment mode. This is because at the start of concentration adjustment mode, the carbon dioxide concentration in the air inside the chamber is far from the set value. Subsequently, when the elapsed time becomes longer than the predetermined time, the second condition is met, and the controller (110) executes the second concentration control.

[0282] (11-6) Modification 6 The controller (110) may again determine the airtightness index of the transport container (1) based on the actual volume (Vs) obtained by the estimation operation and an index showing the rate of change of the internal pressure (Pi) when the internal pressure (Pi) changes. Specifically, as shown in Figure 29, in step ST161, the controller (110) obtains the Cv value using the airtightness measurement mode described above. Next, in step ST162, the controller (110) estimates the actual volume (Vs) of the internal space (5) using the estimation operation described above. Next, in step ST163, the controller (110) obtains the Cv value again based on the actual volume (Vs) estimated in step ST162. Specifically, in step ST163, the controller (110) executes either a first airtightness measurement mode using the depressurization method or a second airtightness measurement mode using the pressure boosting method. The first and second airtightness measurement modes require V1, i.e., the actual volume (Vs) of the internal space (5), as a parameter for determining the Cv value. Therefore, by using the actual volume (Vs) obtained in step ST162, the Cv value can be determined even if the internal space (5) is not empty. The controller (110) may execute the first airtightness measurement mode at the timings shown in (a) and (b) of Figure 27. The controller (110) may also execute the second airtightness measurement mode at the timings shown in (c) and (d) of Figure 28.

[0283] (11-7) Modification 7 The controller (110) may display the actual volume (Vs) estimated by the estimation operation on the display unit (115). Specifically, as shown in Figure 30, the controller (110) acquires the Cv value in step ST171 and estimates the actual volume (Vs) of the storage space (5) in step ST172. Then, in step ST173, the display unit (115) displays the actual volume (Vs) estimated by the estimation operation. In this embodiment, the display unit (115) further displays the Cv value. This allows the operator to grasp the current actual volume of the storage space (5) and the Cv value of the transport container (1). These parameters are useful for managing the transport container (1).

[0284] The controller (110) may transmit the estimated actual volume (Vs) to a predetermined terminal via a wireless or wired communication line. The terminal may include a server device, a personal computer, a tablet terminal, a smartphone, etc., and may have a function to display the actual volume (Vs). The controller (110) may constitute a control system including the communication line and the terminal.

[0285] (11-8) Modification 8 The pressure sensing unit of the embodiment may have the following configuration.

[0286] As shown in Figure 31, the main body case (171) of the differential pressure sensor (170), which is the pressure sensing unit, is located in the external space (6). Specifically, the main body case (171) is located in the external equipment room (28). The external communication passage (174) is composed of a communication hole formed in the main body case (171), connecting the external space (6) with the inside of the main body case (171). The internal communication passage (173) is formed inside a tube. The tube extends from the main body case (171) to the internal space (5). The differential pressure sensor (170) detects the differential pressure (ΔP) between the internal space (5) and the external space (6). The controller (110) takes the external pressure as atmospheric pressure and calculates the internal pressure (Pi) based on the differential pressure (ΔP).

[0287] Alternatively, the pressure detection unit may have an internal pressure sensor and an external pressure sensor. The internal pressure sensor and the external pressure sensor are separate and independent sensors. The internal pressure sensor is located in the internal space (5). Specifically, the internal pressure sensor is located in the primary flow path (29a) of the internal air flow path (29). The external pressure sensor is located in the external space (6). Specifically, the external pressure sensor is located in the external equipment room (28). The internal pressure sensor detects the internal pressure (Pi), and the external pressure sensor detects the external pressure (Po). The controller (110) calculates the differential pressure (ΔP) by subtracting the external pressure from the internal pressure (Pi).

[0288] Alternatively, the pressure sensing unit may have only an internal pressure sensor. The internal pressure sensor is placed in the internal space (5). Specifically, the internal pressure sensor is placed in the primary flow path (29a) of the internal air flow path (29). The controller (110) takes the external pressure as atmospheric pressure and calculates the differential pressure (ΔP) by subtracting the atmospheric pressure from the internal pressure (Pi).

[0289] (11-9) Modification 9 The air pump (231) of the embodiment is an example of a pressure regulating unit. The pressure regulating unit may have the following configuration.

[0290] The pressure adjustment unit may be a depressurizing pump that reduces the pressure inside the chamber (5). By reducing the internal pressure (Pi) with the depressurizing pump, the actual volume (Vs) of the internal chamber (5) can be estimated by the depressurizing method. In addition, the Cv value can be determined by the depressurizing method.

[0291] The pressure adjustment unit may be a ventilation device that introduces outside air into the interior space (5). The ventilation device has an air intake port for supplying outside air into the interior space (5) and a fan for supplying air. By supplying outside air into the interior space (5) with the supply fan, the internal pressure (Pi) can be increased. This makes it possible to estimate the actual volume (Vs) of the interior space (5) by the pressure boosting method, or to determine the Cv value by the pressure boosting method.

[0292] The pressure adjustment unit may be a ventilation device that discharges the internal air into the external space (6). The ventilation device has an exhaust port for exhausting the internal air into the external space (6) and an exhaust fan. By exhausting the internal air into the external space (6) with the exhaust fan, the internal pressure (Pi) can be reduced. This makes it possible to estimate the actual volume (Vs) of the internal space (5) by the depressurization method, or to determine the Cv value by the depressurization method.

[0293] The pressure adjustment unit may be a heating unit that heats the air inside the chamber. The heating unit may be the internal heat exchanger (15) of the embodiment, or it may be another device such as a heater. When the air inside the chamber is heated, the internal pressure (Pi) increases. This makes it possible to estimate the actual volume (Vs) of the internal space (5) by the pressure boosting method, or to determine the Cv value by the pressure boosting method.

[0294] The pressure adjustment unit may also be a cooling unit that cools the air inside the chamber. The cooling unit may be the internal heat exchanger (15) of the embodiment, or it may be another device such as a Peltier. When the air inside the chamber is cooled, the internal pressure (Pi) decreases. This makes it possible to estimate the actual volume (Vs) of the internal space (5) by the depressurization method, or to determine the Cv value by the depressurization method.

[0295] (11-10) Modification 10 The controller (110) may perform only one or two of the three airtightness measurement modes described above. Even with this configuration, the controller (110) can estimate the actual volume (Vs) based on the Cv value obtained in one of the airtightness measurement modes.

[0296] Alternatively, the controller (110) does not need to be able to perform the airtightness measurement mode. For example, the user may input a Cv value measured by another measuring instrument to the controller (110), and the controller (110) may estimate the actual volume (Vs) based on the input Cv value. The controller (110) may also estimate the actual volume (Vs) based on the Cv value obtained at the time of shipment of the transport container (1).

[0297] The controller (110) may perform only one of the first estimation operation or the second estimation operation. The controller (110) may estimate the actual volume (Vs) without using the Cv value. The memory device (112) of the controller (110) has data for estimating the actual volume (Vs), and the controller (110) may estimate the actual volume (Vs) based on this data and the first index. This data may be, for example, a relational expression or data table showing the relationship between the first time (Δt1) and the actual volume (Vs) obtained under predetermined environmental conditions. Since the rate of pressure change is correlated with the actual volume (Vs) of the internal space (5), the actual volume (Vs) can be estimated using such a relational expression or data table.

[0298] The controller (110) may use the rate of increase or decrease in the internal pressure (Pi) directly as the first indicator for determining the actual volume (Vs), rather than the first time (Δt1).

[0299] The controller (110) does not necessarily have to use the detected value of the internal air temperature (Tr) to determine the actual volume (Vs). The user may initiate the estimation operation when the internal air temperature (Tr) is at a predetermined temperature.

[0300] (12) In other embodiments, the controller (110) may adjust the flow rate of the first air in flow rate control so that the concentration of other components in the air inside the chamber reaches a set value. The controller (110) may adjust the concentration of the first air in concentration control so that the concentration of other components in the air inside the chamber reaches a set value. The controller may perform only flow rate control and not concentration control. The controller (110) may perform only either the first flow rate control or the second flow rate control. The controller (110) may perform only either the first concentration control or the second concentration control.

[0301] The air composition adjustment device (90) may supply the processed gas, after adsorbing predetermined components in the air processing unit (95), as first air to the chamber space (5). In this case, the controller (110) can adjust the concentration of the components in the first air by adjusting the opening and closing timing of the gas discharge valve (272). This is because the concentration of the components in the gas processed by the adsorption operation also changes during that period.

[0302] The air composition adjustment device (90) may have a flow path for mixing the first gas desorbed from the adsorption cylinders (234, 235) during the desorption operation with the second gas that has passed through the adsorption cylinders (234, 235), which are the adsorption parts during the adsorption operation, and a control valve for adjusting the mixing ratio of these gases. The controller (110) may adjust the concentration of the components of the first air by adjusting this mixing ratio.

[0303] The air composition control device (90) may be configured not to perform any modes other than the concentration control mode.

[0304] The controller (110) may estimate the carbon dioxide generation rate and oxygen consumption rate by other means, such as by the values ​​detected by the sensor.

[0305] The air composition adjustment device (90) may measure the actual volume (Vs) of the internal space (5) using, for example, an ultrasonic sensor or a camera that images the internal space (5).

[0306] The air processing unit (95) may be configured to separate the outside air (atmosphere) into nitrogen-enriched gas and oxygen-enriched gas using a gas separation membrane. The gas separation membrane has the characteristic that the nitrogen permeation rate is lower than both the oxygen permeation rate and the carbon dioxide permeation rate. Therefore, in the air processing unit (95), the outside air is separated into oxygen-enriched gas that has permeated through the gas separation membrane and nitrogen-enriched gas that has not permeated through the gas separation membrane.

[0307] The transport container (1) may be a container for land transport, such as by truck or rail. The transport container (1) does not need to have an air cooling function.

[0308] The air composition control device (90) may be applied to stationary storage facilities where fruits, vegetables, or flowers are stored, rather than to storage facilities for transport containers.

[0309] The controller (110) may be installed in the transport refrigeration unit (10), server unit, user-operated terminal unit, etc. The controller (110) may be composed of two or more physically separated control elements.

[0310] While embodiments and modifications have been described above, it will be understood that a variety of changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the embodiments, modifications, and other embodiments described above may be combined or substituted as appropriate, as long as they do not impair the functions covered by this disclosure.

[0311] The designations "first," "second," "third," etc., mentioned above are used to distinguish between the terms to which these designations are attached, and do not limit the number or order of those terms.

[0312] (13) Reference Form: Cargo such as fruits and vegetables and flowers is loaded into the interior space of a transport container. When cargo is loaded into the interior space, the actual volume of the interior space, in other words, the actual volume of air present in the interior space, changes. Hereinafter, this volume will be referred to as the actual volume of the interior space. The actual volume of the interior space is useful for managing transport containers. The reference form provides an estimation device that can estimate the actual volume of the interior space of a transport container.

[0313] The reference configuration applies to the estimation device. The estimation device comprises a pressure adjustment unit that changes the pressure inside the storage space of a transport container, a pressure detection unit for determining the internal pressure of the storage space, and a controller that performs an estimation operation to estimate the actual volume of the storage space based on a first index indicating the rate of change of the internal pressure when the internal pressure changes.

[0314] In the reference configuration, the pressure adjustment unit (231) changes the internal pressure. When cargo is loaded into the internal space and the actual volume of the internal space changes, the rate of change of the internal pressure also changes. Specifically, if the actual volume increases, the rate of increase or decrease in the internal pressure slows down, and if the actual volume decreases, the rate of increase or decrease in the internal pressure speeds up. Therefore, the controller estimates the actual volume of the internal space based on a first indicator that shows the rate of change of the internal pressure.

[0315] The estimation device of the reference embodiment has a controller similar to that of the embodiments and modified examples described above. The controller does not need to perform flow rate control to adjust the flow rate of the first air so that the concentration of components in the air inside the chamber reaches a set value during the operation of the air conveying section. The estimation device preferably has a display unit that displays the actual volume estimated by the estimation operation.

[0316] As described above, this disclosure is useful for air composition adjustment devices and transport containers.

[0317] 2 Container body (storage compartment) 5 Interior space 6 Exterior space 40 Ventilation system (outside air intake) 90 Air composition adjustment device 95 Air processing unit 110 Controller 161 Oxygen sensor (concentration sensor) 162 Carbon dioxide sensor (concentration sensor) 170 Differential pressure sensor (pressure detection unit) 231 Air pump (air conveying unit, pump, pressure adjustment unit) 234,235 Adsorption unit (adsorption cylinder) 241 First gas pipe (first flow path) 255 Bypass connecting pipe (third flow path) 256 Bypass valve (flow control valve) 272 Gas discharge valve (on / off valve) 275 Gas supply pipe (first flow path) 281 Measuring piping (second flow path) 291 Auxiliary pump (air conveying unit, pump) S Supply path

Claims

A supply path (S) connects the external space (6) and the internal space (5) inside the storage compartment (2), An air processing unit (95) is provided in the supply passage (S) and adjusts the composition of the air, An air transport unit (231, 291) transports the processed gas, whose composition has been adjusted in the air processing unit (95), to the interior space (5) as first air via the supply passage (S), The system includes an air processing unit (95) and a controller (110) that controls the air transport unit (231, 291), The controller (110) performs flow rate control during the operation of the air transport unit (231, 291) to adjust the flow rate of the first air so that the concentration of the components in the air inside the chamber reaches a set value. Air composition adjustment device. 　 The controller (110) executes a concentration adjustment mode in which it supplies the first air from the supply path (S) to the interior space (5) in response to an operation command. The controller (110) performs the flow rate control during the concentration adjustment mode. The air composition adjustment device according to claim 1. 　 The aforementioned air transport unit includes a variable flow rate pump (231, 291), The controller (110) controls the flow rate of the first air by controlling the pumps (231, 291) in the flow rate control. An air composition adjustment device according to claim 1 or 2. 　 The system further includes an outside air introduction unit (40) that introduces outside air from the outside space (6) into the inside space (5) as second air without passing through the supply path (S), The controller (110) adjusts the flow rate of the first air and the flow rate of the second air in the flow rate control so that the concentration of the component in the air inside the chamber reaches the set value. An air composition adjustment device according to claim 1 or 2. 　 The aforementioned outside air intake section (40) includes a ventilation device (40) that supplies the outside air into the interior space (5) of the storage unit. The air composition adjustment device according to claim 4. 　 The controller (110) performs concentration control during the operation of the air transport unit (231, 291) to adjust the concentration of the components in the first air so that the concentration of the components in the air inside the chamber reaches the set value. An air composition adjustment device according to any one of claims 1 to 5. 　 The air processing unit (95) includes two adsorption units (234, 235) that perform an adsorption operation to adsorb components from the air and a desorption operation to desorb the adsorbed components. A first flow path (244, 275) through which a processed gas whose composition has been adjusted in the adsorption section (234, 235) flows, A second flow path (281) discharges the processing gas from the first flow path (244, 275) to the outside of the chamber, The system further includes an on / off valve (272) provided in the second flow path (281), The controller (110) controls the timing of opening and closing the on-off valve (272) in the concentration control, thereby adjusting the concentration of the components of the first air. The air composition adjustment device according to claim 6. 　 The air processing unit (95) includes two adsorption units (234, 235) that perform an adsorption operation to adsorb components from the air and a desorption operation to desorb the adsorbed components. A first flow path (244, 275) through which a processed gas whose composition has been adjusted in the adsorption section (234, 235) flows, A third flow path (255) introduces the outside air from the outside space (6) into the first flow path (244, 275) by bypassing the air processing unit (95), The system further includes a flow control valve (256) that adjusts the flow rate of the outside air flowing from the third flow path (255) into the first flow path (244, 275), The controller (110) controls the concentration of the components of the first air by controlling the flow control valve (256) in the concentration control. The air composition adjustment device according to claim 6. 　 The controller (110) determines a target flow rate to bring the carbon dioxide concentration in the air inside the chamber to the set value, and in the flow rate control, adjusts the flow rate of the first air to the target flow rate. An air composition adjustment device according to any one of claims 1 to 8. 　 The controller (110) is The carbon dioxide generation rate of fruits, vegetables or flowers in the aforementioned storage space (5) is estimated. The target flow rate is determined based on the estimated carbon dioxide generation rate. The air composition adjustment device according to claim 9. 　 The controller (110) estimates the carbon dioxide generation rate based on the actual volume of the interior space (5) and the carbon dioxide concentration in the air inside the interior. The air composition adjustment device according to claim 10. 　 The controller (110) determines a target concentration to bring the oxygen concentration in the air inside the chamber to the set value, and in the concentration control, adjusts the oxygen concentration of the first air to the target concentration. 　 An air composition adjustment device according to any one of claims 6 to 8. 　 The controller (110) is The oxygen consumption rate of fruits, vegetables or flowers in the aforementioned storage space (5) is estimated. The target concentration is determined based on the oxygen consumption rate. The air composition adjustment device according to claim 12. 　 The controller (110) estimates the oxygen consumption rate based on the actual volume of the interior space (5) and the oxygen concentration in the air inside the interior. The air composition adjustment device according to claim 13. 　 A pressure adjustment unit (231) that changes the pressure in the internal space (5) of the chamber, The system further comprises a pressure detection unit (170) for detecting the internal pressure of the internal space (5) of the storage chamber, The controller (110) estimates the actual volume based on a first indicator showing the rate of change of the internal pressure when the internal pressure changes. The air composition adjustment device according to claim 11 or 14. 　 The chamber further comprises concentration sensors (161, 162) for detecting the carbon dioxide concentration or oxygen concentration in the air inside the chamber, The controller (110) adjusts the flow rate of the first air so that the concentration detected by the concentration sensors (161, 162) reaches the set value in the flow rate control. An air composition adjustment device according to any one of claims 1 to 15. 　 The chamber further comprises concentration sensors (161, 162) for detecting the carbon dioxide concentration or oxygen concentration in the air inside the chamber, The controller (110) adjusts the concentration of the components of the first air so that the concentration detected by the concentration sensors (161, 162) reaches the set value in the concentration control. 　 An air composition adjustment device according to any one of claims 6 to 8. 　 The storage chamber is further equipped with a carbon dioxide sensor (162) for detecting the carbon dioxide concentration in the air inside the chamber. The controller (110) is configured to determine a target flow rate to bring the carbon dioxide concentration of the air inside the chamber to the set value. The controller (110) is The first flow rate control, which adjusts the flow rate of the first air to the target flow rate, The flow rate of the first air is adjusted so that the carbon dioxide sensor (162) detects the concentration of the first air, and a second flow rate control is performed as the flow rate control. An air composition adjustment device according to any one of claims 1 to 17. 　 The controller (110) is If the first condition indicating that the carbon dioxide concentration in the air inside the chamber is close to the set value is not met, the first flow rate control is executed. If the first condition is met, the second flow rate control is executed. The air composition adjustment device according to claim 18. 　 The chamber is equipped with an oxygen sensor (161) for detecting the oxygen concentration in the air inside the chamber. The controller (110) is configured to determine a target concentration for bringing the oxygen concentration of the air inside the chamber to the set value. The controller (110) is The first concentration control, which adjusts the oxygen concentration of the first air to the target concentration, The oxygen concentration of the first air is adjusted so that the concentration detected by the oxygen sensor (161) reaches the set value, and a second concentration control is performed as the concentration control. An air composition adjustment device according to any one of claims 6 to 8. 　 The controller (110) executes the first concentration control when the second condition indicating that the oxygen concentration in the air inside the chamber is close to the set value is not met. If the second condition is met, the second concentration control is executed. The air composition adjustment device according to claim 20. The first indicator is an indicator that shows the rate of increase in the internal pressure of the chamber. The air composition adjustment device according to claim 15. 　 The first indicator is an indicator that shows the rate of decrease in the internal pressure of the chamber. The air composition adjustment device according to claim 15. 　 The aforementioned interior space (5) is the interior space of the transport container (1), The controller (110) estimates the actual volume based on an airtightness index indicating the airtightness of the transport container (1) and the first index. The air composition adjustment device according to claim 15. 　 The controller (110) executes a first airtightness measurement mode to determine the airtightness index based on the internal pressure, the external pressure of the external space (6), and an index indicating the rate of decrease in the internal pressure (Pi) when the internal pressure decreases. The air composition adjustment device according to claim 24. 　 The controller (110) executes a second airtightness measurement mode to determine the airtightness index based on the internal pressure, the external pressure of the external space (6), and an index indicating the rate of increase of the internal pressure when the internal pressure increases. The air composition adjustment device according to claim 24. 　 The controller (110) executes the first airtightness measurement mode or the second airtightness measurement mode when the internal storage space (5) is empty. An air composition adjustment device according to claim 25 or claim 26. 　 The pressure adjustment unit is an air transport unit (231) that supplies air to the internal space (5) of the chamber, The controller (110) executes a third airtightness measurement mode to determine the airtightness index based on the internal pressure, the external pressure of the external space (6), and the inflow rate of air supplied to the internal space (5) during a period when the internal pressure of the air conveying unit (231) is constant during operation. The air composition adjustment device according to claim 24. 　 The controller (110) executes the third airtightness measurement mode when there is cargo in the storage space (5). The air composition adjustment device according to claim 28. 　 The controller (110) estimates the actual volume based on the internal pressure, the external pressure of the external space (6), and the first indicator. An air composition adjustment device according to any one of claims 15, 22 to 26. 　 The pressure detection unit includes a differential pressure sensor (170) that detects the differential pressure between the outside air and the inside air of the storage unit. The air composition adjustment device according to claim 30. 　 An air composition adjustment device (90) according to any one of claims 1 to 31, The chamber is equipped with a refrigerant circuit (11) for cooling the internal space (5). Refrigeration equipment for transportation. 　 A transport container comprising an air composition adjustment device (90) according to any one of claims 1 to 32.

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