Air composition adjustment device

Abstract

To provide an air composition control device that can evaluate the airtightness of the interior space even while the air composition control device is in operation. [Solution] An air composition adjustment device for adjusting the composition of the air in the internal space (5) of a container (1), comprising: a composition adjustment unit (200) that supplies a gas to be treated, which has a different composition from the outside air generated by processing outside air, to the internal space (5); a control unit (110) that controls the composition adjustment unit (200); and a first pressure detection unit (170) that detects the pressure in the internal space (5), wherein the composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be treated to the internal space (5), and the control unit (110) evaluates the airtightness of the internal space (5) based on the pressure change in the internal space (5) caused by the operation of the transport unit (231a, 231b).

Description

【Technical Field】 【0001】 The present disclosure relates to an air composition control device. 【Background Art】 【0002】 Patent Document 1 discloses a transport container. The transport container has a transport refrigeration device. The transport refrigeration device cools the air in the storage space of the container. The transport container has an air composition control device for adjusting the composition of the air in the storage space. The air composition control device adjusts the oxygen concentration and the carbon dioxide concentration of the air in the storage space. 【Prior Art Documents】 【Patent Documents】 【0003】 【Patent Document 1】 Japanese Unexamined Patent Application Publication No. 2018-148877 【Summary of the Invention】 【Problems to be Solved by the Invention】 【0004】 Cargo such as fruits and vegetables and flowers is loaded into the storage space of the transport container. In order to maintain the freshness of the fruits and vegetables and flowers during transportation, the oxygen concentration and the carbon dioxide concentration in the storage space are adjusted. Therefore, the airtightness of the storage space is evaluated using a device such as a compressor. However, when evaluating the airtightness of the storage space using such a device, it is necessary to perform the evaluation before loading the cargo into the transport container or at the location where the device is installed. Therefore, the timing and location for evaluating the airtightness are limited, and it is preferable to evaluate the airtightness of the storage space even during the operation of the air composition control device. 【0005】 The present disclosure aims to provide an air composition control device that can evaluate the airtightness of the storage space even during the operation of the air composition control device. 【Means for Solving the Problems】 【0006】 The first aspect is, An air composition adjustment device for adjusting the air composition in the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), The system includes a first pressure detection unit (170) for detecting the pressure in the internal space (5) of the chamber, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the inside space (5), The control unit (110) evaluates the airtightness of the internal space (5) based on the pressure changes in the internal space (5) caused by the operation of the transport units (231a, 231b). It is an air composition adjustment device. 【0007】 In the first embodiment, the airtightness of the internal space (5) can be evaluated by using a transport unit (231a, 231b) that can grasp the flow rate of gas flowing into the internal space (5). Therefore, since external equipment such as a compressor is not required for the airtightness evaluation, it is possible to suppress restrictions on the location and timing of the airtightness evaluation. In particular, since the airtightness of the internal space (5) can be evaluated even during the transport of the container (1), the airtightness of the internal space (5) can be evaluated even when cargo is loaded into the internal space (5). 【0008】 A second aspect is, in the first aspect, The control unit (110) determines an airtightness index, which is an indicator of the airtightness of the internal storage space (5). 【0009】 In the second embodiment, the airtightness of the interior space (5) can be evaluated relatively easily by using an airtightness index. 【0010】 A third aspect is, in the second aspect, The control unit (110) determines the airtightness of the internal storage space (5) based on the airtightness index. 【0011】 In the third embodiment, the airtightness of the internal space (5) can be determined by using an airtightness index. For example, if the airtightness is very low, it will not be possible to maintain the internal air at a predetermined temperature, nor will it be possible to maintain the internal air at a predetermined controlled air composition. In such cases, the container (1) cannot be used for transporting goods such as fruits and vegetables, so by determining the airtightness of the internal space (5), it is possible to quickly determine whether the transport container is usable and whether the transport container (1) needs to be repaired. 【0012】 A fourth aspect is, in the second aspect, The control unit (110) determines whether or not the air composition adjustment device can be operated based on the airtightness index. 【0013】 In the fourth embodiment, the airtightness index can be used to determine whether or not the air composition adjustment device can be operated. As a result, if the airtightness is high enough to maintain the internal space (5) at a predetermined temperature by operating the transport refrigeration device, normal transport can be carried out with only refrigeration or freezing without using the air composition adjustment device. 【0014】 The fifth aspect is as described in the fourth aspect. The container (1) is equipped with a refrigeration device (10) for cooling the air inside the internal space (5), The control unit (110) determines whether or not to operate the refrigeration system (10) based on the airtightness index. 【0015】 In the fifth embodiment, in addition to determining whether the air composition adjustment device in the fourth embodiment can be operated, it is also possible to determine whether the refrigeration device can be operated. 【0016】 The sixth aspect is one of the first to fifth aspects, The first pressure detection unit (170) includes a differential pressure sensor that detects the differential pressure between the outside air and the inside air of the storage unit. 【0017】 In the sixth aspect, when the pressure of the outside air in the warehouse is the standard atmospheric pressure, the pressure in the warehouse space (5) can be detected by the differential pressure. 【0018】 The seventh aspect is any one of the second to fifth aspects, further comprising a second pressure detector (180) for detecting the pressure of the outside air in the warehouse, the control unit (110) obtains the airtightness index based on the detection values of the first pressure detector (170) and the second pressure detector (180). 【0019】 In the seventh aspect, the change in the internal pressure of the container (1) is affected by the pressure of the outside air in the warehouse. Therefore, by using the pressure value of the outside air in the warehouse, the accuracy of the airtightness evaluation of the warehouse space (5) can be improved. 【0020】 The eighth aspect is any one of the second to seventh aspects, the control unit (110) obtains the airtightness index based on the pressure in the warehouse space (5) during a first period in which the conveying units (231a, 231b) are controlled so that the pressure in the warehouse space (5) is maintained within a predetermined range. 【0021】 In the eighth aspect, when the internal pressure in the warehouse is kept constant, it can be considered that the amount of gas inflow and the amount of gas outflow are equal. Utilizing this, the airtightness of the warehouse space (5) when the internal pressure is constant can be evaluated. 【0022】 The ninth aspect is in the eighth aspect, further comprising a blower (35) for circulating the air inside the warehouse space (5), the control unit (110) obtains the airtightness index based on the pressure in the warehouse space (5) during a period in the first period when the wind speed of the blower (35) is in a steady state. 【0023】 In the ninth embodiment, the pressure value of the interior space (5) temporarily changes due to changes in the air velocity of the blower (35). In particular, when the pressure in the interior space (5) is constant, the effect of changes in the air velocity of the blower (35) is significant. Therefore, by determining the airtightness index during the period when the air velocity of the blower (35) is in a steady state, a more accurate airtightness index can be obtained. 【0024】 The tenth aspect is, in the eighth or ninth aspect, The control unit (110) executes a first mode in which outside air is introduced into the interior space (5) without changing its composition. The first period is the period during which the first mode is being executed. 【0025】 In the tenth embodiment, the airtightness index can be determined while the first mode is being executed. 【0026】 The eleventh aspect is, in the eighth or ninth aspect, The control unit (110) executes a second mode in which the gas to be processed is introduced into the chamber space (5). The first period is the period during which the second mode is being executed. 【0027】 In the eleventh embodiment, the airtightness index can be determined by the constant pressure method while the second mode is being executed. 【0028】 The twelfth aspect is as follows, in the eleventh aspect: The control unit (110) determines the airtightness index based on the flow rate of the gas to be processed supplied to the internal space (5) of the chamber. 【0029】 In the twelfth embodiment, the flow rate of the gas to be treated can be determined by operating the transport section (231a, 231b), thereby allowing the airtightness index to be determined. 【0030】 The 13th aspect is one of the first to seventh aspects, The control unit (110) controls the transport units (231a, 231b) to perform a pressure-boosting operation that increases the pressure in the internal space (5), and evaluates the airtightness of the internal space (5) based on the change in the pressure detected by the first pressure detection unit (170) during the pressure-boosting operation. 【0031】 In the 13th embodiment, the airtightness of the internal space (5) can be evaluated even when the internal pressure is rising. 【0032】 The 14th aspect is one of the 1st to 7th aspects, The control unit (110) controls the transport units (231a, 231b) to perform a pressure reduction operation to reduce the pressure in the internal space (5), and evaluates the airtightness of the internal space (5) based on the change in pressure detected by the first pressure detection unit (170) during the pressure reduction operation. 【0033】 In the 14th embodiment, the airtightness of the internal space (5) can be evaluated even when the internal pressure is decreasing. 【0034】 The 15th aspect is, in the 13th or 14th aspect, The control unit (110) performs a switching operation to switch between a plurality of operating modes performed by the air composition adjustment device, and evaluates the airtightness of the interior space (5) based on the change in the pressure detected by the first pressure detection unit (170) when the operating mode is switched by the switching operation. 【0035】 In the 15th embodiment, the pressure in the internal space (5) changes when the operating mode is switched. This change in internal pressure can be used to evaluate the airtightness of the internal space (5). 【0036】 The sixteenth aspect is as described in the fifteenth aspect. The operating modes include a first mode in which outside air is introduced into the internal space (5) without changing its composition, a second mode in which the gas to be treated, generated by processing the outside air, is introduced into the internal space (5), and a third mode in which the operation of the conveying units (231a, 231b) is stopped. The control unit (110) evaluates the airtightness of the interior space (5) based on the increase in the detected pressure of the first pressure detection unit (170) when switching from the second mode to the first mode, or from the third mode to the first mode. 【0037】 In the 16th embodiment, the airtightness of the internal space (5) can be evaluated when the internal pressure increases due to the switching of the operating mode. 【0038】 The 17th aspect is the same as the 15th aspect, The operating modes include a first mode in which outside air is introduced into the internal space (5) without changing its composition, a second mode in which the gas to be treated, generated by processing the outside air, is introduced into the internal space (5), and a third mode in which the operation of the conveying units (231a, 231b) is stopped. The control unit (110) evaluates the airtightness of the interior space (5) based on the decrease in the detected pressure of the first pressure detection unit (170) when switching from the first mode to the third mode, or from the second mode to the third mode. 【0039】 In the 17th embodiment, if the internal pressure decreases due to switching the operating mode, the airtightness of the internal space (5) can be evaluated. 【0040】 The 18th aspect is one of the 2nd to 17th aspects, The container (1) is provided with ventilation openings (41, 42) that connect the internal space (5) and the external space, and an opening / closing lid (45) that adjusts the degree of opening of the ventilation openings (41, 42). The control unit (110) evaluates the degree of opening of the ventilation openings (41, 42) based on the airtightness index. 【0041】 In the 18th embodiment, the degree of opening of the door can be determined based on an airtightness index. This makes it possible to determine whether the door is operating normally. 【0042】 The 19th aspect is one of the 1st to 18th aspects, The control unit (110) evaluates the airtightness of the internal space (5) of the container (1) while it is being transported. 【0043】 In the 19th embodiment, it becomes unnecessary to evaluate the airtightness of the warehouse space (5) before transporting the collected cargo. As a result, the airtightness of the warehouse space (5) can be evaluated even when the collected cargo is loaded into the container, so the airtightness of the warehouse space (5) can be evaluated at any desired time without considering location or time. [Brief explanation of the drawing] 【0044】 [Figure 1] Figure 1 is a schematic perspective view of a transport refrigeration system according to an embodiment. [Figure 2] Figure 2 is a cross-sectional view of a transport container equipped with a transport refrigeration device according to an embodiment. [Figure 3] Figure 3 is a piping diagram showing the refrigerant circuit of the transport refrigeration system of the embodiment. [Figure 4] 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] Figure 5 is a piping diagram showing the configuration of the air composition adjustment device according to the embodiment. [Figure 6] Figure 6 is a diagram corresponding to Figure 5, showing the air composition adjustment device that performs the first operation of the gas supply operation. [Figure 7] Figure 7 is a diagram corresponding to Figure 5, showing the air composition adjustment device that performs the second operation of the gas supply operation. [Figure 8] Figure 8 corresponds to Figure 5, which shows an air composition adjustment device that performs outside air intake. [Figure 9] Figure 9 is a block diagram showing the configuration of the control unit included in the air composition adjustment device of the embodiment. [Figure 10] Figure 10 is a table showing the timing of operation in the 8% oxygen concentration mode. [Figure 11] Figure 11 is a table showing the timing of operation in the 5% oxygen concentration mode. [Figure 12] Figure 12 shows a flowchart, timing chart, and formulas to explain the first airtightness measurement mode. [Figure 13] Figure 13 shows a flowchart, timing chart, and formulas to explain the second airtightness measurement mode. [Figure 14] Figure 14 shows a flowchart, timing chart, and formulas to explain the third airtightness measurement mode. [Figure 15] Figure 15 is a flowchart illustrating the process for determining the airtightness of the interior space of the storage area. [Figure 16] Figure 16 shows the changes in pressure inside the storage compartment during an example of the operation of a transport refrigeration system. [Figure 17] Figure 17 shows the changes in pressure within the chamber space during an example of the operation of an air composition control device. [Figure 18] Figure 18 is a flowchart illustrating the operation for determining the opening degree of the ventilation opening of the ventilation device. [Figure 19] Figure 19 is a diagram corresponding to Figure 2 of the transport container in Modification Example 1. [Figure 20] Figure 20 is a diagram corresponding to Figure 2 of the transport container in Modification Example 2. [Modes for carrying out the invention] 【0045】 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. 【0046】 (1) Overview This disclosure relates to a transport container (1). This transport container (1) is a reefer container capable of controlling the internal temperature. This transport container (1) is used to transport perishable goods (e.g., fruits, vegetables, flowers, etc.) that respire by taking in oxygen (O2) from the air and releasing carbon dioxide (CO2). Transport container (1) is an example of container (1). 【0047】 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. 【0048】 The container body (2) is a storage unit for the fresh produce mentioned above. 【0049】 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. 【0050】 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 communicates with the space above the floor plate (3) (i.e., the space where the cargo is stored). 【0051】 (2) Basic configuration of transport refrigeration equipment The transport refrigeration unit (10) comprises a casing (20), a refrigerant circuit (11) that performs the refrigeration cycle, an external fan (34), and an internal fan (35). The transport refrigeration unit (10) is an example of a refrigeration unit (10). 【0052】 (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, the casing (20) is equipped with a refrigerant circuit (11), an outer fan (34), and an inner fan (35). 【0053】 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). 【0054】 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). 【0055】 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). 【0056】 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). In this way, the internal fan (35) circulates the air inside the internal space (5). The internal fan (35) is an example of a blower (35). 【0057】 (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). 【0058】 (2-3) Operation of transport refrigeration equipment The transport refrigeration unit (10) performs a cooling operation to cool the air inside the transport container (1). 【0059】 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. 【0060】 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. 【0061】 Let's explain the airflow inside the storage unit. The air present in the storage unit space (5) flows through the intake port (26) into the primary flow path (29a) of the storage unit airflow path (29), and is blown out into the secondary flow path (29b) by the storage unit fan (35). The air that flows into the secondary flow path (29b) is cooled as it passes through the storage unit heat exchanger (15), and is then blown out from the outlet (27) into the underfloor flow path (4), and flows back into the storage unit space (5) through the underfloor flow path (4). 【0062】 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). 【0063】 (3) Ventilation system The transport refrigeration unit (10) is equipped with a ventilation unit (40). The ventilation unit (40) ventilates the interior space (5) of the container body (2). The ventilation unit (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). 【0064】 (3-1) Configuration of the ventilation system 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. 【0065】 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 internal space (5) and the external space (6). The air supply passage (41) and exhaust passage (42) provided in a transport container are examples of ventilation openings (41, 42). 【0066】 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. 【0067】 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. 【0068】 As shown in Figure 4, the opening / closing lid (45) has an air intake opening (46) and an exhaust opening (47). Each of the air intake opening (46) and the exhaust opening (47) penetrates 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). The opening / closing lid (45) provided on the transport container (1) in this way adjusts the opening degree of the air intake passage (41) and the exhaust passage (42). 【0069】 (3-2) Operation of the ventilation system 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). 【0070】 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). 【0071】 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. 【0072】 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. 【0073】 When the opening / closing cover (45) is in the position shown in Figure 4(C), the entire air intake port (41a) overlaps with the air intake opening (46), and the entire exhaust port (42a) overlaps with the exhaust opening (47). Therefore, 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(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 air intake passage (41) and the exhaust passage (42) are fully open. Consequently, in this state, both the air intake flow rate and the exhaust flow rate reach their maximum flow rates. 【0074】 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. 【0075】 (4) Air composition adjustment device (4-1) Basic configuration of an air composition control device The air composition control device (100) is installed in the transport refrigeration unit (10) to perform 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). 【0076】 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. 【0077】 (4-2) Filter unit, outside air pipe The filter unit (220) is a box-shaped component. The filter unit (220) is installed in the external 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. 【0078】 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). 【0079】 (4-3) Main Unit The main unit (200) processes the ambient air outside the container to generate a treated gas with a different composition from the outside air. The air composition adjustment device (100) supplies the generated treated gas to the interior space (5) of the container body (2). Specifically, the air composition adjustment device (100) separates the outside air into a nitrogen-enriched gas with a higher nitrogen concentration and lower oxygen concentration than the outside air, and an oxygen-enriched gas with a lower nitrogen concentration and higher oxygen concentration than the outside air. The main unit (200) is an example of a composition adjustment unit (200). 【0080】 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 components. The unit case (201) houses an inlet pipe (242), a suction pipe (243), a first gas pipe (244), and a second gas pipe (245). 【0081】 (4-4) Air pump The air pump (231) is an example of a conveying unit. 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). The air pump (231) conveys outside air and the gas to be processed into the internal space (5). 【0082】 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). 【0083】 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). 【0084】 (4-5)Introduction 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). 【0085】 (4-6) Suction tube 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). 【0086】 (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). 【0087】 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. 【0088】 (4-8) Switching valve 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. 【0089】 The first switching valve (232) has its first port connected to one end of the first suction cylinder (234). The first switching valve (232) 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 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). 【0090】 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). 【0091】 (4-9) Adsorption tube Each of the first adsorption cylinder (234) and the second adsorption cylinder (235) is a component 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. 【0092】 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 a pressurized state where the pressure is higher than atmospheric pressure, and desorbing nitrogen and water under a reduced pressure state 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). 【0093】 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). 【0094】 (4-10) Second gas pipe 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 connecting 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 connecting 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. 【0095】 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 of the main pipe (246) to the other, and blocks air to flow in the reverse direction. 【0096】 (4-11) Purge pipe 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). 【0097】 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). 【0098】 (4-12) Exhaust connection pipe An exhaust connecting pipe (271) is connected to the first gas pipe (244). One end of the exhaust connecting 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 connecting 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 connecting pipe (271) is connected to one end of the gas discharge pipe (276). 【0099】 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). 【0100】 (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). 【0101】 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. 【0102】 (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 into 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). 【0103】 (4-15) Measurement piping A measuring pipe (281) is connected to the first gas pipe (244). The measuring pipe (281) is the pipe that connects the first gas pipe (244) to the sensor unit (160). One end of the measuring pipe (281) is connected to the downstream side of the check valve (264) in the first gas pipe (244). The other end of the measuring pipe (281) is connected to the sensor unit (160). 【0104】 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). 【0105】 (4-16) Bypass pipe A bypass connecting pipe (255) is connected to the 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). 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). 【0106】 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 inside space (5) of the storage unit without changing its composition. 【0107】 (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). 【0108】 The oxygen sensor (161) is a zirconia current type 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 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). 【0109】 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). 【0110】 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). 【0111】 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. 【0112】 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 flows 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 flows from the measuring pipe (281) into the sensor case (163). 【0113】 (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. 【0114】 (4-19) Differential pressure sensor and internal temperature sensor The air composition adjustment 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) comprises a main body case (171), a sensor unit (172) disposed inside the main body case (171), an internal communication passage (173) connecting the inside of the main body case (171) to the internal space (5), and an external communication passage (174) connecting the inside of the main body case (171) to the external space (6). The differential pressure sensor (170) is an example of the first pressure detection unit of this disclosure. 【0115】 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). 【0116】 The air composition adjustment 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). 【0117】 (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 generates nitrogen-enriched gas by processing the outside air and supplies this nitrogen-enriched gas to the inside space (5). During the gas supply operation, the ventilation exhaust valve (151) is opened. 【0118】 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. 【0119】 (5-1-1) 1st action As shown in Figure 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). 【0120】 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). 【0121】 Meanwhile, the depressurizing 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 depressurizing pump (231b). The depressurizing 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). 【0122】 (5-1-2)Second operation As shown in Figure 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. 【0123】 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). 【0124】 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). 【0125】 (5-2) Open air intake operation The air composition adjustment device (100) performs an outside air intake operation. The outside air intake operation is the operation of supplying outside air, which is the atmosphere, to the interior space (5) of the storage facility without changing its composition. 【0126】 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. 【0127】 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). 【0128】 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). 【0129】 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. 【0130】 (6) Control Unit The air composition adjustment device (100) has a control unit (110). As shown in Figure 9, the control unit (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. 【0131】 The control unit (110) controls the components of the air composition adjustment device (100). The control unit (110) controls the main unit (200). The control unit (110) receives the measured values ​​from the oxygen sensor (161) and the carbon dioxide sensor (162). The control unit (110) controls the air pump (231), the first switching valve (232), and the second switching valve (233). The control unit (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). The control unit (110) outputs predetermined information to the notification unit (115). The notification unit (115) is provided in the transport refrigeration device (10). The notification unit (115) displays or emits predetermined information based on signals input from the control unit (110). 【0132】 The control unit (110) controls the ventilation device (40). Specifically, the control unit (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). 【0133】 The control unit (110) evaluates the airtightness of the interior space (5) based on the pressure changes in the interior space (5) caused by the operation of the air pump (231). Details of the airtightness evaluation will be described later. 【0134】 (7) Operating Mode The operating modes of the air composition control device (100) will now be described. The control unit (110) causes the air composition control device (100) to perform four operating modes. These operating modes include an 8% oxygen concentration mode, a 5% oxygen concentration mode, an outside air intake mode, and a breathing mode. 【0135】 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 8% oxygen concentration mode and the 5% oxygen concentration mode are second modes for introducing the gas to be treated into the interior space (5). In other words, the second mode includes the 8% oxygen concentration mode and the 5% oxygen concentration mode. The outside air introduction mode is a first mode in which the air composition control device (100) introduces outside air into the interior space (5) without changing its composition. The breathing mode is a third mode in which the air composition control device (100) stops operating the air pump (231) and 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 facility due to the breathing of the cargo inside the facility. 【0136】 In these operating modes, the oxygen concentration of the gas supplied to the chamber increases in the order of 5% oxygen concentration mode, 8% oxygen concentration mode, and outside air intake mode. The control unit (110) performs a switching operation to switch between the multiple operating modes performed by the air composition adjustment device (100). By switching the operating mode through the switching operation, the air composition adjustment device (100) adjusts the air composition in the chamber space (5). 【0137】 (7-1) Oxygen concentration 8% mode As shown in Figure 10, in the 8% oxygen concentration mode, the air composition adjustment device (100) repeatedly performs the first and second operations alternately. Between the first and second operations, the air composition adjustment device (100) performs a pressure equalization operation. During the pressure equalization operation, the control unit (110) opens the purge valve (251). This quickly equalizes the internal pressures of the first adsorption cylinder (234) and the second adsorption cylinder (235). 【0138】 In the 8% oxygen concentration mode, the control unit (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, more nitrogen components are desorbed because the pressure inside the adsorption cylinders decreases compared to the beginning, resulting in the generation of nitrogen-enriched gas with a relatively high oxygen concentration. 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%. 【0139】 (7-2) Oxygen concentration 5% mode As shown in Figure 11, in the 5% oxygen concentration mode, the air composition adjuster (100) repeatedly performs the first and second operations alternately, similar to the 8% oxygen concentration mode. Between the first and second operations, the air composition adjuster (100) performs a pressure equalization operation. 【0140】 In the 5% oxygen concentration mode, the control unit (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 control unit (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). Thereafter, for the remainder of each operation, the control unit (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%. 【0141】 (7-3) Outdoor 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 control unit (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 outside air intake mode can increase the oxygen concentration of the air inside the storage unit. 【0142】 (7-4) Breathing Modes In breathing mode, the control unit (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. 【0143】 (8) Evaluation of the airtightness of the interior space The control unit (110) evaluates the airtightness of the internal space (5). Specifically, the control unit (110) determines an airtightness index, which is an indicator of the airtightness of the internal space (5). The airtightness index is the Cv value. A higher Cv value indicates lower airtightness of the internal space (5). A lower Cv value indicates higher airtightness of the internal space (5). 【0144】 (8-1) Measurement of Cv value The control unit (110) executes an airtightness measurement mode for determining the Cv value. The airtightness measurement mode in 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. Details of each airtightness estimation mode will be described below. 【0145】 (8-1-1) First airtightness measurement mode (depressurization method) In the first airtightness measurement mode, the Cv value is automatically measured using the depressurization method. The control unit (110) controls the air pump (231) to perform a depressurization operation that reduces the internal pressure of the storage space (5). The control unit (110) evaluates the airtightness of the internal pressure based on the change in pressure detected by the differential pressure sensor (170) during the depressurization operation. This section explains how the control unit (110) determines the Cv value of the storage space (5) during the depressurization operation. 【0146】 In this embodiment, the control unit (110) increases the internal pressure of the storage space (5) by operating the air pump (231). The control unit (110) then determines the Cv value based on the rate at which the internal pressure decreases. 【0147】 Specifically, as shown in Figure 12, in step ST11, the control unit (110) operates the air pump (231). In step ST11, the control unit (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 executes an outside air introduction mode (first mode) in which outside air is supplied directly to the interior space (5) by the pressurizing pump (231a). However, as will be described in detail later, the air composition adjustment device (100) may also perform an 8% oxygen concentration mode or a 5% oxygen concentration mode (second mode) in which it closes the bypass valve (256), opens the gas supply valve (273), and supplies the gas processed by the air processing unit (95) to the interior space (5) by the pressure reducing pump (231b), similar to the gas supply operation described above. In this way, the control unit (110) may determine the airtightness index based on the flow rate of the gas to be processed supplied to the interior space (5). 【0148】 When air is introduced into the internal space (5), the internal pressure (Pi) increases in step ST12. In step ST13, the control unit (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 control unit (110) calculates the internal pressure (Pi) by adding the external pressure (Po) (atmospheric pressure) to the differential pressure (ΔP). 【0149】 In step ST14, the control unit (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 12, the control unit (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). 【0150】 Next, in step ST15, the control unit (110) acquires the external pressure (Po), differential pressure (ΔP), and internal air temperature (Tr) at the second time point (P2). Then, in step ST16, the control unit (110) calculates the Cv value based on equations (1), (2), and (3) in Figure 12. Here, Qo is the outflow rate of gas flowing out of the internal space (5) at the first time (Δt1) [m³ 3Qi is the flow rate of gas flowing into the storage space (5) at the first time (Δt1) [m 3 The 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. 【0151】 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 control unit (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. 【0152】 (8-1-2) Second airtightness measurement mode (pressure boosting method) In the second airtightness measurement mode, the Cv value is automatically measured using the pressure boosting method. The control unit (110) controls the air pump (231) to perform a pressure boosting operation that increases the internal pressure of the storage space (5). The control unit (110) evaluates the airtightness of the storage space (5) based on the rate of increase of the internal pressure, which is the pressure change detected by the differential pressure sensor (170) during the pressure boosting operation. Here, we will explain how to determine the Cv value of the storage space (5) during the pressure boosting operation of the control unit (110). 【0153】 Specifically, as shown in Figure 13, in step ST21, the control unit (110) operates the air pump (231). The details of the control in step ST21 are the same as in step ST11. 【0154】 In step ST22, the control unit (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 smaller 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 13, the control unit (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 internal space (5) is low, the rate of increase of the internal pressure (Pi) will be lower, and the first time (Δt1) will be longer. When the internal space (5) is highly airtight, the rate of increase in internal pressure (Pi) is high, and the first time (Δt1) becomes shorter. Thus, the rate of increase in internal pressure, or more precisely, the time it takes for the internal pressure to reach a predetermined pressure, serves as an indicator of the airtightness of the internal space (5) of the transport container (1). 【0155】 Next, in step ST23, the control unit (110) acquires the internal pressure (Pi), external pressure (Po), differential pressure (ΔP), internal air temperature (Tr), and inflow flow rate (Qi) at the second time point (t2). 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). 【0156】 Next, in step ST24, the control unit (110) calculates the Cv value based on equations (1), (2), and (3) in Figure 13. The details of the method for calculating the Cv value are the same as in the first airtightness measurement mode. 【0157】 (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 control unit (110) operates the air pump (231). When the air pump (231) reaches a steady state, the internal pressure of the storage space (5) becomes constant. The control unit (110) determines the Cv value based on the internal pressure (Pi) at this time. 【0158】 Specifically, as shown in Figure 14, in step ST31, the control unit (110) operates the air pump (231). The details of the control in step ST31 are the same as in step ST11. 【0159】 Next, in step ST32, the control unit (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 control unit (110) determines whether the internal pressure (Pi) is within a predetermined range for a predetermined second time (Δt2). If the internal pressure (Pi) is constant for a predetermined second time (Δt2), the process proceeds to step ST33. The second time (Δt2) is an example of the first period. That is, the second time (Δt2) is the period during which the outside air introduction mode, the 8% oxygen concentration mode, or the 5% oxygen concentration mode is running. 【0160】 In step ST33, the control unit (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). Then, in step ST34, the control unit (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. Therefore, the Cv value can be determined 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 internal 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 internal space (5) to directly measure the inflow rate (Qi). 【0161】 (9) Operation by the control unit to determine the airtightness of the interior space The control unit (110) determines the airtightness of the internal space (5) and whether or not to operate the air composition adjustment device (100) based on the obtained Cv value. An example of the operation of the control unit (110) to determine the airtightness of the internal space (5) will be explained using Figure 15. 【0162】 In step ST41, the control unit (110) determines whether the Cv value is lower than the first value. If it is determined that the Cv value is lower than the first value (YES in step ST41), step ST42 is executed. If it is determined that the Cv value is greater than or equal to the first value (NO in step ST41), the control unit (110) determines that the transport refrigeration unit (10) and the air composition adjustment device (100) cannot be operated. The first value is, for example, 4.12. If the Cv value is 4.12 or greater, the airtightness of the interior space (5) is sufficiently low, the transport refrigeration unit (10) cannot sufficiently cool the air inside the storage space, and it is also difficult to adjust the composition of the air inside the storage space using the air composition adjustment device (100). 【0163】 In step ST42, the control unit (110) determines whether the Cv value is lower than the second value. If it is determined that the Cv value is lower than the second value (YES in step ST42), step ST43 is executed. If it is determined that the Cv value is greater than or equal to the second value (NO in step ST42), the control unit (110) determines that the air composition adjustment device (100) cannot be operated. The second value is, for example, 3.33. If the Cv value is 3.33 or greater and 4.12 or less, the airtightness of the internal space (5) is relatively low, and the internal air can be sufficiently cooled by the transport refrigeration device (10), but it becomes difficult to adjust the composition of the internal air by the air composition adjustment device (100). Therefore, in this case, the air composition adjustment device (100) is not operated, and fruits and vegetables can be transported by operating only the transport refrigeration device (10). 【0164】 In step ST43, the control unit (110) determines that the airtightness of the interior space (5) is sufficiently high and decides that it is possible to operate the transport refrigeration unit (10) and the air composition adjustment unit (100). In this case, the transport refrigeration unit (10) can sufficiently cool the air inside the storage unit, and the air composition adjustment unit (100) can sufficiently adjust the composition of the air inside the storage unit. 【0165】 In step ST44, the control unit (110) outputs predetermined information to the notification unit (115). This predetermined information includes information that the container body (2) will be replaced or repaired, or that the air composition adjustment device (100) is not operational. 【0166】 (10) Evaluation of the airtightness of the interior space by the control unit during operation of the transport refrigeration system. The control unit (110) evaluates the airtightness of the internal space (5) while the transport refrigeration unit (10) is in operation. Specifically, the control unit (110) evaluates the airtightness of the internal space (5) while the air composition adjustment unit (100) is in operation. The control unit (110) may also evaluate the airtightness of the internal space (5) while the transport container is in transport, or it may evaluate the airtightness of the internal space (5) when the transport container is placed in a predetermined location. 【0167】 The control unit (110) evaluates the airtightness of the internal space (5) based on the change in pressure detected by the differential pressure sensor (170) when the operating mode is switched by a switching operation during past operation of the air composition adjustment device, i.e., the change in internal pressure. The operation of the control unit (110) to determine the airtightness of the internal space (5) will be explained below based on the operation example of the transport refrigeration device (10) shown in Figure 16. 【0168】 After loading cargo such as fruits and vegetables into the storage space and closing the door of the container body (2), the transport refrigeration unit (10) is started to lower the internal temperature to the set temperature. The internal temperature is then maintained at the set temperature until time point A. After time point A has elapsed, the control unit (110) starts the operation of the air composition adjustment device (100). The control unit (110) executes the 8% oxygen concentration mode. The internal pressure increases as the gas to be treated flows into the storage space (5). After the internal pressure becomes constant, the 8% oxygen concentration mode continues until time point B. At this point, while the air composition adjustment device (100) is running, the wind speed of the internal fan (35) is switched. In Figure 16, while the 8% oxygen concentration mode is running, the wind speed of the internal fan (35) is switched at times b1 and b2. When the rotation speed of the internal fan (35) is switched, the wind speed changes, and the internal pressure changes temporarily as a result. 【0169】 During the period from time A to time B, the internal pressure can be considered constant. Therefore, the period from time A to time B is considered the first period, and the airtightness of the internal space (5) can be evaluated by performing the third airtightness measurement mode (constant pressure method). However, as mentioned above, during this first period, the internal pressure temporarily changes due to the switching of the fan speed of the internal fan (35). Therefore, the control unit (110) evaluates the airtightness of the internal space (5) based on the internal pressure during the period in the first period when the fan speed of the internal fan (35) is in a steady state. Here, a steady state means a state in which the fan speed has stabilized after the switching of the rotation speed of the internal fan (35). A steady state refers to the state of the fan speed of the internal fan (35) during the period in which the internal pressure becomes constant after the switching of the fan speed of the internal fan (35). In a steady state, the rotation speed of the internal fan (35) is constant. 【0170】 After time point B has elapsed, the control unit (110) switches to the 5% oxygen concentration mode. As a result, the flow rate of the gas to be treated into the chamber space (5) decreases, and the internal pressure decreases. Therefore, the control unit (110) can evaluate the airtightness of the chamber space (5) by executing the first airtightness measurement mode (depressurization method). Furthermore, since the internal pressure becomes constant after decreasing, the airtightness of the chamber space (5) can be evaluated using the third airtightness measurement mode (constant pressure method). 【0171】 When the internal storage space (5) reaches the desired oxygen and carbon dioxide concentrations, the control unit (110) controls the air composition adjustment device (100) to maintain the oxygen and carbon dioxide concentrations in the internal storage space (5). If the oxygen concentration in the internal storage space (5) decreases at time C, the control unit (110) switches to an outside air introduction mode to bring outside air into the internal storage space (5). At this time, the flow rate of gas flowing into the internal storage space (5) increases, causing the internal pressure to increase. Therefore, the control unit (110) can evaluate the airtightness of the internal storage space (5) by executing the second airtightness measurement mode (pressure boosting method). The control unit (110) can evaluate the airtightness of the internal storage space (5) based on the increase in the detected pressure of the differential pressure sensor (170) when switching from the 5% oxygen concentration mode to the outside air introduction mode. 【0172】 Although not shown in the diagram, when the oxygen concentration increases due to the execution of the outside air intake mode, the control unit (110) switches to breathing mode, which stops the operation of the air pump (231). At this time, the inflow of gas into the interior space (5) stops, and the internal pressure decreases. Therefore, the control unit (110) can evaluate the airtightness of the interior space (5) by executing the first airtightness measurement mode (depressurization method). The control unit (110) can evaluate the airtightness of the interior space (5) based on the decrease in the pressure detected by the differential pressure sensor (170) when switching from outside air intake mode to breathing mode. 【0173】 (11) Abnormality detection of ventilation system Next, we will explain how to determine abnormalities in the ventilation device (40) based on the airtightness index value of the internal space (5). The control unit (110) evaluates the opening of the supply air passage (41) and exhaust air passage (42) of the ventilation device (40) based on the airtightness index. Specifically, the opening area S of the supply air passage (41) and exhaust air passage (42) is determined for each position of the opening / closing lid (45). The Cv value obtained based on this opening area S is taken as the true value, and by determining how much the actual Cv value of the internal space (5) deviates from the true value, it is possible to determine whether the position control of the opening / closing lid (45) is performed correctly. The flow of the control unit (110)'s determination will be explained using Figures 17 and 18. 【0174】 The changes in internal pressure due to the operation of the air composition control device (100) shown in Figure 17 will be explained. The outside air introduction mode is executed with the supply air passage (41) and exhaust air passage (42) fully closed. This increases the internal pressure, which is then maintained at a constant level. After the internal pressure is maintained at a constant level, the opening / closing lid (45) is rotated to a predetermined position. This opens a portion of the supply air passage (41) and exhaust air passage (42), causing the internal pressure to decrease. After the internal pressure is maintained at a constant level with the supply air passage (41) and exhaust air passage (42) partially open, the supply air passage (41) and exhaust air passage (42) are fully opened. This further decreases the internal pressure. After that, the supply air passage (41) and exhaust air passage (42) are closed and the outside air introduction mode is executed again. 【0175】 In step ST51, the control unit (110) determines the Cv1 value of the internal space (5) while the outside air introduction mode is running. If Cv1 is to be determined when the internal pressure is rising, the second airtightness measurement mode is executed. If Cv1 is to be determined when the internal pressure is constant, the third airtightness measurement mode is executed. 【0176】 In step ST52, the control unit (110) determines the Cv2 value when a portion of the supply air passage (41) and exhaust air passage (42) are opened. If Cv2 is to be determined when the internal pressure is decreasing, the first airtightness measurement mode is executed. If Cv2 is to be determined when the internal pressure is constant, the third airtightness measurement mode is executed. 【0177】 In step ST53, the control unit (110) determines the Cv3 value when a portion of the air supply passage (41) and exhaust passage (42) are opened. Cv3 can be calculated using the formula Cv3 = opening area S / 18.45. The opening area S is a theoretical value set according to the rotation angle of the opening / closing cover (45). If we assume that the opening area S is largest when the rotation angle of the opening / closing cover (45) is α, then the opening area S increases as the rotation angle of the opening / closing cover (45) moves from zero to α. 【0178】 In step ST54, the control unit (110) determines whether ΔCv is 1 or less. ΔCv can be calculated using the formula ΔCv = |Cv3 - (Cv1 - Cv2)|. If ΔCv is 1 or less, the operation of the opening / closing lid (45) and the position of the opening / closing lid (45) are considered normal, and this control flow ends. On the other hand, if ΔCv is greater than ΔCv1, the operation of the opening / closing lid (45) and the position of the opening / closing lid (45) are considered abnormal, and step ST55 is executed. 【0179】 Here, the value obtained by subtracting the Cv value after partially opening the air supply passage (41) and exhaust passage (42) (Cv2) from the Cv value before partially opening the air supply passage (41) and exhaust passage (42) (Cv1) (ΔCv) represents the amount of gas leakage caused solely by partially opening the air supply passage (41) and exhaust passage (42). Therefore, if the opening / closing cover (45) is operating normally, ΔCv will be zero. However, if the opening of the air supply passage (41) and exhaust passage (42) is greater than the theoretical value S due to an abnormality in the position control of the opening / closing cover (45), ΔCv will be a positive value. If the opening of the air supply passage (41) and exhaust passage (42) is smaller than the theoretical value S, ΔCv will be a negative value. 【0180】 In step ST55, the control unit (110) issues an alarm indicating that the position control of the opening / closing cover (45) is abnormal. This allows for the repair or replacement of the ventilation device (40). 【0181】 (12) Characteristics (12-1) Feature 1 The control unit (110) of the air composition adjustment device (100) in this embodiment evaluates the airtightness of the internal space (5) based on the pressure change in the internal space (5) caused by the operation of the air pump (231). 【0182】 By using an air pump (231) that can control the gas flow rate in this way, the airtightness of the internal space (5) can be evaluated. Therefore, external equipment such as a compressor is not required for airtightness evaluation, and the location and timing of the airtightness evaluation can be set as appropriate. In particular, it can be performed even during the transport of the container (1), so the airtightness of the internal space (5) can be evaluated even when cargo is loaded in the container. 【0183】 (12-2) Feature 2 The control unit (110) of this embodiment determines an airtightness index, which is an indicator of the airtightness of the internal space (5). 【0184】 By using an airtightness index, the airtightness of the interior space (5) can be evaluated relatively easily. 【0185】 (12-3) Feature 3 The control unit (110) of this embodiment determines the airtightness of the internal space (5) based on the airtightness index. 【0186】 By using an airtightness index, the airtightness of the internal space (5) can be determined. If the airtightness is sufficiently low, it will not be possible to maintain the internal air at a predetermined temperature, nor will it be possible to maintain the internal air at a predetermined controlled air composition. In such cases, the transport container (1) cannot be used for transporting goods such as fruits and vegetables. Therefore, by determining the airtightness of the internal space (5), it is possible to quickly confirm whether the transport container is usable and whether repairs to the transport container (1) are necessary. 【0187】 (12-4) Feature 4 The control unit (110) of this embodiment determines whether or not to operate the air composition adjustment device (100) based on the airtightness index. 【0188】 By using an airtightness index, it is possible to determine whether or not the air composition control device (100) can be operated. As a result, if the airtightness is high enough to maintain the internal space (5) at a predetermined temperature by operating the transport refrigeration device (10), normal transport can be carried out with only refrigeration or freezing without using the air composition control device (100). 【0189】 (12-5) Feature 5 This embodiment includes a differential pressure sensor that detects the differential pressure between the outside air and the inside air of the storage unit. 【0190】 When the pressure of the air outside the chamber is set to standard atmospheric pressure, the pressure inside the chamber (5) can be detected by the pressure difference. 【0191】 (12-6) Feature 6 In this embodiment, the control unit (110) determines an airtightness index based on the pressure in the internal space (5) during a first period in which the air pump (231) is controlled so that the pressure in the internal space (5) is maintained within a predetermined range. 【0192】 When the internal pressure is kept constant, the gas inflow and outflow can be considered equal. This can be used to evaluate the airtightness of the internal space (5) when the internal pressure is constant. 【0193】 (12-7) Feature 7 The control unit (110) of this embodiment determines an airtightness index based on the pressure in the interior space (5) during the period in the first period when the wind speed of the interior fan (35) is in a steady state. 【0194】 The pressure value in the interior space (5) changes temporarily due to changes in the airflow speed of the interior fan (35). In particular, when the pressure in the interior space (5) is constant, the effect of changes in the airflow speed of the interior fan (35) is significant. Therefore, by determining the airtightness index during the period when the airflow speed of the interior fan (35) is in a steady state, a more accurate airtightness index can be obtained. 【0195】 (12-8) Feature 8 The control unit (110) of this embodiment executes an outside air introduction mode (first mode) that introduces outside air into the interior space (5) without changing its composition, and the first period is the period during which the first mode is being executed. 【0196】 While the outside air intake mode is running, the airtightness index can be determined using the third airtightness measurement mode (constant pressure method). 【0197】 (12-9) Feature 9 The control unit (110) of this embodiment executes a second mode, which is an 8% oxygen concentration mode and a 5% oxygen concentration mode, for introducing the gas to be treated into the chamber space (5), and the first period is the period during which the second mode is being executed. 【0198】 During operation in either the 8% oxygen concentration mode or the 5% oxygen concentration mode, the airtightness index can be determined using the third airtightness measurement mode (constant pressure method). 【0199】 (12-10) Feature 10 The control unit (110) of this embodiment determines the airtightness index based on the flow rate of the gas to be treated supplied to the internal space (5). Since the flow rate of the gas to be treated can be determined, the airtightness index can be determined from this. 【0200】 (12-11) Feature 11 In this embodiment, the control unit (110) performs a pressure-boosting operation to increase the pressure in the internal space (5) by controlling the air pump (231). The control unit (110) evaluates the airtightness of the internal space (5) based on the change in pressure detected by the differential pressure sensor (170) during the pressure-boosting operation. This allows for evaluation of the airtightness of the internal space (5) even when the internal pressure is rising. 【0201】 (12-12) Feature 12 In this embodiment, the control unit (110) controls the air pump (231) to perform a pressure reduction operation that reduces the pressure in the internal space (5). The control unit (110) evaluates the airtightness of the internal space (5) based on the change in pressure detected by the differential pressure sensor (170) during the pressure reduction operation. This allows for evaluation of the airtightness of the internal space (5) even when the internal pressure is decreasing. 【0202】 (12-13) Feature 13 In this embodiment, the control unit (110) evaluates the airtightness of the internal space (5) based on the change in pressure detected by the differential pressure sensor (170) when the operating mode is switched by a switching operation. 【0203】 During operation of the air composition control device (100), the pressure in the internal space (5) changes when switching operating modes based on the oxygen concentration or carbon dioxide concentration in the internal space (5). This can be used to evaluate the airtightness of the internal space (5) using the first airtightness measurement mode, the second airtightness measurement mode, or the third airtightness measurement mode. 【0204】 (12-14) Feature 14 The control unit (110) evaluates the airtightness of the interior space (5) based on the increase in the pressure detected by the differential pressure sensor (170) when switching from the 8% oxygen concentration mode or the 5% oxygen concentration mode to the outside air intake mode, or from the breathing mode to the outside air intake mode. 【0205】 If the internal pressure increases due to the switching of the operating mode, the airtightness of the internal space (5) can be evaluated using the second airtightness measurement mode. 【0206】 (12-15) Feature 15 In this embodiment, the control unit (110) evaluates the airtightness of the internal space (5) based on the decrease in the pressure detected by the differential pressure sensor (170) when switching from the outside air intake mode to the breathing mode, or from the 8% oxygen concentration mode or the 5% oxygen concentration mode to the breathing mode. 【0207】 If the internal pressure decreases due to the switching of the operating mode, the airtightness of the internal space (5) can be evaluated using the first airtightness measurement mode. 【0208】 (12-16) Feature 16 The control unit (110) of this embodiment evaluates the opening degree of the ventilation openings (41, 42) of the ventilation device (40) provided in the transport container (1) based on an airtightness index. 【0209】 In this way, the degree of opening of the ventilation openings (41, 42) can be determined based on the airtightness index. This makes it possible to determine whether the opening / closing cover (45) is functioning correctly. 【0210】 (12-17) Feature 17 The control unit (110) of this embodiment evaluates the airtightness of the internal space (5) of the transport container (1) while it is being transported. 【0211】 The airtightness of the interior space (5) of the shipping container (1) can be evaluated in real time. This allows for constant monitoring of the conditions of the interior space (5). 【0212】 (13) Modified examples of embodiments The above-described embodiment may also have the following modified configuration. In principle, the differences from the above embodiment will be explained below. 【0213】 (13-1) Variation 1 As shown in Figure 19, the main body case (171) of the differential pressure sensor (170), which is the first pressure detection unit of Modified Example 1, 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 control unit (110) takes the external pressure as atmospheric pressure and determines the internal pressure (Pi) based on the differential pressure (ΔP). 【0214】 (13-2) Variation 2 The air composition adjustment device (100) of the modified example 2 has an external pressure sensor (180), which is a second pressure detection unit (180) that detects the pressure of the air outside the storage unit. The first pressure detection unit (170) is an internal pressure sensor (170). The internal pressure sensor (170) and the external pressure sensor (180) are separate and independent sensors. The internal pressure sensor (170) is located in the internal space (5). Specifically, the internal pressure sensor (170) is located in the primary flow path (29a) of the internal air flow path (29). The external pressure sensor (180) is located in the external space (6). Specifically, the external pressure sensor (180) is located in the external equipment room (28). The internal pressure sensor (170) detects the internal pressure (Pi), and the external pressure sensor (180) detects the external pressure (Po). The control unit (110) calculates the differential pressure (ΔP) by subtracting the external pressure from the internal pressure (Pi). In this way, the airtightness index of the internal space (5) is determined based on the detected values ​​of the internal pressure sensor (170) and the external pressure sensor (180). 【0215】 (12) Other embodiments The sensor unit (160) may include a refrigerant leak sensor (not shown) that detects refrigerant leaking from the transport refrigeration unit (10) into the storage space (5). 【0216】 The values ​​detected by each sensor in the sensor unit (160) may be corrected based on the pressure value. For example, an infrared sensor has a light-emitting part and a light-receiving part. Light emitted from the light-emitting part passes through the gas and is received by the light-receiving part. The gas concentration is determined based on the intensity of the light after it has passed through the gas, as received by the light-receiving part. According to Beer's law, the amount of light absorbed by the gas is proportional to the gas concentration. Based on this property and the ideal gas law (PV=nRT), it has been found that the molar concentration of a gas is proportional to the pressure. Therefore, the detected values ​​of the gas concentration (oxygen, carbon dioxide, refrigerant gas, etc.) shown by the various sensors in the sensor unit (160) will differ depending on the internal pressure. From this, for example, correction data showing the relationship between the internal pressure and the correction value can be stored in the control unit (110), and the control unit (110) can calculate the concentration of the gas present in the internal space (5) that is independent of the internal pressure, based on the obtained internal pressure of the internal space (5), the gas concentration, and the correction data. 【0217】 The airtightness index can be any index that indicates the airtightness of the internal space (5), and is not limited to the Cv value. 【0218】 The control unit (110) can evaluate the airtightness of the internal space (5) while the air composition adjustment device (100) is in operation. For example, in the "evaluation of the airtightness of the internal space by the control unit during operation of the transport refrigeration system" of the above embodiment, the control unit (110) may evaluate the airtightness of the internal space (5) using a second airtightness measurement mode by utilizing the change in internal pressure that increases when the operating mode is switched from the breathing mode to the outside air introduction mode. Alternatively, the airtightness of the internal space (5) may be evaluated using a first airtightness measurement mode by utilizing the change in internal pressure that decreases when the operating mode is switched from the second mode, which is the 8% oxygen concentration mode and the 5% oxygen concentration mode, to the breathing mode. 【0219】 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. 【0220】 The first pressure detection unit (170) 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 control unit (110) takes the external pressure as atmospheric pressure and calculates the differential pressure (ΔP) by subtracting the atmospheric pressure from the internal pressure (Pi). 【0221】 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. 【0222】 The transport refrigeration unit (10) does not necessarily include an air composition control unit (100). The air composition control unit (100) and the transport refrigeration unit (10) may be separate and independent units. In this case, the internal fan (35) may be included in the air composition control unit (100). 【0223】 The refrigerant circuit (11) of the transport refrigeration system (10) may be configured to enable defrost operation to remove frost accumulating on the internal heat exchanger (15) which functions as an evaporator. In this case, the first to third airtightness measurement modes are not performed on the internal space (5) during defrost operation. That is, the airtightness of the internal space (5) during defrost operation is not evaluated. Furthermore, the airtightness of the internal space (5) during so-called pull-down, when the air temperature inside the internal space (5) drops to a set value through the operation of the transport refrigeration system (10), is not evaluated. 【0224】 Regarding the airtightness determination operation of the control unit (110) in the above embodiment, in step ST41, the control unit (110) may determine whether or not at least one of the transport refrigeration unit (10) and the air composition adjustment unit (100) can be operated. 【0225】 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. 【0226】 The designations "1st," "2nd," "3rd," 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. [Industrial applicability] 【0227】 As described above, this disclosure is useful for estimation devices, air composition adjustment devices, and transport refrigeration devices. [Explanation of symbols] 【0228】 1. Shipping container (container) 5. Interior space 6 Outside space 35. Interior fan (blower) 41,42 Ventilation vent 45 Opening and closing lid 100 Air composition adjustment device 110 Control Unit 170 Differential pressure sensor (first pressure detection unit) 180 External pressure sensor (second pressure detection unit) 200 Main unit (composition adjustment section) 231a, 231b Conveying section

Claims

[Claim 1] An air composition adjustment device for adjusting the air composition in the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), The system includes a first pressure detection unit (170) for detecting the pressure in the internal space (5) of the storage chamber, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the inside space (5), The control unit (110) determines an airtightness index, which is an indicator of the airtightness of the internal space (5), based on the pressure Pi in the internal space (5), the pressure Po in the external space, the air temperature Tr in the internal space (5), and the flow rate Qo of the gas flowing out of the internal space (5) within a predetermined period, when the pressure in the internal space (5) changes due to the operation of the transport unit (231a, 231b). The airtightness of the interior space (5) is evaluated based on the airtightness index. Air composition adjustment device. [Claim 2] An air composition adjustment device for adjusting the air composition of the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), A first pressure detection unit (170) detects the pressure in the internal space (5) of the storage chamber, The storage area (5) is further equipped with a blower (35) for circulating the air inside the storage space, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the internal space (5) of the chamber. The control unit (110) Based on the pressure in the internal space (5) during the period in which the conveying section (231a, 231b) is controlled so that the pressure in the internal space (5) is maintained within a predetermined range, and during the period in which the air velocity of the blower (35) is in a steady state, an airtightness index, which is an index indicating the airtightness of the internal space (5), is determined. The airtightness of the interior space (5) is evaluated based on the airtightness index. Air composition adjustment device. [Claim 3] The control unit (110) determines the airtightness of the interior space (5) based on the airtightness index. An air composition adjustment device according to claim 1 or 2. [Claim 4] The control unit (110) determines whether or not the air composition adjustment device can be operated based on the airtightness index. An air composition adjustment device according to claim 1 or 2. [Claim 5] The container (1) is equipped with a refrigeration device (10) for cooling the air inside the interior space (5), The control unit (110) determines whether or not the refrigeration system (10) can be operated based on the airtightness index. The air composition adjustment device according to claim 4. [Claim 6] The first pressure detection unit (170) includes a differential pressure sensor that detects the differential pressure between the outside air and the inside air of the storage unit. An air composition adjustment device according to claim 1 or 2. [Claim 7] It further includes a second pressure detection unit (180) for detecting the pressure of the air outside the chamber, The control unit (110) determines the airtightness index based on the detected values ​​of the first pressure detection unit (170) and the second pressure detection unit (180). An air composition adjustment device according to claim 1 or 2. [Claim 8] The control unit (110) determines the airtightness index based on the pressure in the internal space (5) during a first period in which the transport units (231a, 231b) are controlled so that the pressure in the internal space (5) is maintained within a predetermined range. The air composition adjustment device according to claim 1. [Claim 9] The interior space (5) is further equipped with a blower (35) for circulating the air inside, The control unit (110) determines the airtightness index based on the pressure in the interior space (5) during the period in the first period when the wind speed of the blower (35) is in a steady state. The air composition adjustment device according to claim 8. [Claim 10] The control unit (110) executes a first mode in which outside air is introduced into the interior space (5) without changing its composition. The first period is the period during which the first mode is being executed. The air composition adjustment device according to claim 8. [Claim 11] The control unit (110) executes a second mode in which the gas to be processed is introduced into the chamber space (5). The first period is the period during which the second mode is being executed. The air composition adjustment device according to claim 8. [Claim 12] An air composition adjustment device for adjusting the air composition of the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), The system includes a first pressure detection unit (170) for detecting the pressure in the internal space (5) of the storage chamber, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the internal space (5) of the chamber. The control unit (110) A second mode is performed in which the gas to be treated is introduced into the chamber space (5). During the period in which the second mode is being executed, and during the first period in which the transport units (231a, 231b) are controlled so that the pressure in the internal space (5) is maintained within a predetermined range, an airtightness index, which is an index indicating the airtightness of the internal space (5), is determined based on the pressure in the internal space (5). The airtightness of the interior space (5) is evaluated based on the airtightness index. Air composition adjustment device. [Claim 13] The control unit (110) determines the airtightness index based on the flow rate of the gas to be processed supplied to the internal space (5) of the chamber. The air composition adjustment device according to claim 11 or 12. [Claim 14] (Claim 13 before amendment) The control unit (110) controls the transport units (231a, 231b) to perform a pressure-boosting operation that increases the pressure in the internal space (5), and evaluates the airtightness of the internal space (5) based on the change in the pressure detected by the first pressure detection unit (170) during the pressure-boosting operation. The air composition adjustment device according to claim 1. [Claim 15] The control unit (110) controls the transport units (231a, 231b) to perform a pressure reduction operation to reduce the pressure in the internal space (5), and evaluates the airtightness of the internal space (5) based on the change in pressure detected by the first pressure detection unit (170) during the pressure reduction operation. The air composition adjustment device according to claim 1. [Claim 16] The control unit (110) performs a switching operation to switch between a plurality of operating modes performed by the air composition adjustment device, and evaluates the airtightness of the interior space (5) based on the change in the detected pressure of the first pressure detection unit (170) when the operating mode is switched by the switching operation. The air composition adjustment device according to claim 14 or 15. [Claim 17] An air composition adjustment device for adjusting the air composition of the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), An air composition adjustment device comprising a first pressure detection unit (170) for detecting the pressure in the internal space (5) of the chamber, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the internal space (5) of the chamber. The control unit (110) A pressure-boosting operation is performed to increase the pressure in the internal space (5) by controlling the transport section (231a, 231b), The air composition adjustment device performs a switching operation to switch between multiple operating modes, By switching the operating mode, the airtightness of the interior space (5) is evaluated based on the change in the detected pressure of the first pressure detection unit (170) during the pressure boosting operation. Air composition adjustment device. [Claim 18] An air composition adjustment device for adjusting the air composition of the internal space (5) of a container (1), A composition adjustment unit (200) supplies a gas to be treated, which has a different composition from the outside air generated by processing the outside air, to the inside space (5) of the chamber, A control unit (110) that controls the composition adjustment unit (200), An air composition adjustment device comprising a first pressure detection unit (170) for detecting the pressure in the internal space (5) of the chamber, The composition adjustment unit (200) has a transport unit (231a, 231b) that transports outside air or the gas to be processed to the internal space (5) of the chamber. The control unit (110) By controlling the transport section (231a, 231b), a pressure reduction operation is performed to reduce the pressure in the internal space (5), The air composition adjustment device performs a switching operation to switch between multiple operating modes, By switching the operating mode, the airtightness of the interior space (5) is evaluated based on the change in the detected pressure of the first pressure detection unit (170) during the depressurization operation. Air composition adjustment device. [Claim 19] The operating modes include a first mode in which outside air is introduced into the internal space (5) without changing its composition, a second mode in which the gas to be treated, generated by processing the outside air, is introduced into the internal space (5), and a third mode in which the operation of the conveying units (231a, 231b) is stopped. The control unit (110) evaluates the airtightness of the interior space (5) based on the increase in the detected pressure of the first pressure detection unit (170) when switching from the second mode to the first mode, or from the third mode to the first mode. The air composition adjustment device according to claim 16. [Claim 20] The operating modes include a first mode in which outside air is introduced into the internal space (5) without changing its composition, a second mode in which the gas to be treated, generated by processing the outside air, is introduced into the internal space (5), and a third mode in which the operation of the conveying units (231a, 231b) is stopped. The control unit (110) evaluates the airtightness of the interior space (5) based on the decrease in the detected pressure of the first pressure detection unit (170) when switching from the first mode to the third mode, or from the second mode to the third mode. The air composition adjustment device according to claim 16. [Claim 21] The container (1) is provided with ventilation openings (41, 42) that connect the internal space (5) and the external space, and an opening / closing lid (45) that adjusts the degree of opening of the ventilation openings (41, 42). The control unit (110) evaluates the opening degree of the ventilation openings (41, 42) based on the airtightness index. The air composition adjustment device according to claim 1. [Claim 22] The control unit (110) evaluates the airtightness of the internal space (5) of the container (1) while it is being transported. An air composition adjustment device according to claim 1 or 2.

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