JP7799198B2 - Container refrigeration equipment - Google Patents

Description

This disclosure relates to a container refrigeration system.

The container refrigeration system disclosed in Patent Document 1 is equipped with a refrigerant sensor that detects refrigerant leaks inside the container. The refrigerant sensor is positioned downstream of the heat exchanger in the air flow. This allows air that has passed through the heat exchanger to pass through the refrigerant sensor.

JP 2020-101327 A

Even if refrigerant leaks into the air, the air containing the refrigerant is transported through the refrigerator by the fan, so the refrigerant in the air can be detected relatively quickly by the refrigerant sensor. However, even if the refrigerant sensor is located downstream of the heat exchanger in the air flow, the air inside the refrigerator is not circulated while the fan is stopped, so if a refrigerant leak occurs at such a time, it may take some time for the refrigerant sensor to detect the leaked refrigerant.

The purpose of this disclosure is to relatively quickly detect refrigerant leaks inside a container.

The first aspect is
A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
the casing (50, 111) has a first opening (51) that connects the detection portion (110a) and the air passage (19);
The first opening (51) is a container refrigeration unit that opens horizontally or downwardly from the horizontal direction.

In the first aspect, the first opening (51) opens horizontally or downwardly from the horizontal. This makes it easier for leaked refrigerant that has accumulated in the lower part of the container (1) to enter the first opening (51) as it diffuses upward when the first conveyor (30) is stopped. This reduces the time it takes for the detector (110a) to detect leaked refrigerant inside the container (1), enabling relatively rapid detection of the leaked refrigerant.

The second aspect is
A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
The air passage (19) is formed by the first conveyor (30) so that air flows from above to below,
the casing (50, 111) has a first opening (51) that connects the detection portion (110a) and the air passage (19);
The first opening (51) is a container refrigeration unit that opens in a direction perpendicular to the air flow in the air passage (19) or toward the downstream side of the air flow.

When the pressure acting on the detection element (110a) increases due to the air flowing through the air passage (19), the detection element (110a) is more likely to erroneously detect the presence of refrigerant. In contrast, in the second aspect, the first opening (51) is open in a direction perpendicular to the air flow in the air passage (19), thereby suppressing the pressure acting on the first opening (51). This makes it possible to suppress erroneous detection of the presence of refrigerant.

A third aspect is the first or second aspect,
The air conditioner further includes a pressure reducing section (120) disposed in the air passage (19) for reducing the pressure acting on the first opening (51) by the air conveyed by the first conveyer (30).

In the third aspect, the pressure reducing section (120) reduces the pressure acting on the detection section (110a), thereby preventing erroneous detection of the refrigerant.

A fourth aspect is any one of the first to third aspects,
the casing (50, 111) further includes a second opening (52) that connects the detection portion (110a) to the air passage (19);
The second opening (52) opens toward the upstream side of the air flow in the air passage (19).

In the fourth aspect, while the first conveyor (30) is operating, dynamic pressure due to the air flow can be utilized to facilitate air intake through the second opening (52). Furthermore, while the first conveyor (30) is stopped, natural air diffusion can be utilized to facilitate air intake through the first opening (51). In this way, the time from refrigerant leakage to detection can be shortened both during operation and while the first conveyor (30) is stopped.

The fifth aspect is the fourth aspect,
the first conveyor (30) is disposed in the air passage (19);
The first opening (51) and the second opening (52) are disposed below the first conveyor (30).

In the fifth aspect, by being disposed below the first conveyor (30) in the air passage (19), the wind pressure acting on the second opening (52) can be utilized to promote the circulation of air within the casing (50, 111) that flows in through the second opening (52).

A sixth aspect is the fourth or fifth aspect,
The casing (50, 111) has a receiving portion (53) between the second opening (52) and the detection portion (110a) for receiving water that has flowed from the air passage (19) into the second opening (52).

In the sixth aspect, the receiver (53) can prevent water that has flowed into the second opening (52) together with air from splashing into the casing (50, 111). This prevents water from adhering to the detection element (110a), thereby preventing erroneous detection of the refrigerant and malfunction of the detection element (110a).

A seventh aspect is any one of the fourth to sixth aspects,
The casing (50, 111) has an outlet (54) between the second opening (52) and the detection portion (110a) for discharging water that has flowed from the air passage (19) into the second opening (52) to the outside.

Water that flows into the second opening (52) together with air can be discharged outside the casing (50, 111). This achieves the same effect as the sixth aspect.

An eighth aspect is any one of the fourth to seventh aspects,
The casing (50, 111) has a cylindrical portion (62) in which the second opening (52) is formed and which communicates with the detection portion (110a).

In the eighth aspect, the dynamic pressure of the air passing through the tubular portion (62) is reduced when it flows into the casing (50, 111), thereby reducing the wind speed. This reduces the pressure of the air acting on the detection portion (110a), thereby preventing erroneous detection of the refrigerant.

A ninth aspect is the eighth aspect,
The cylindrical portion (62) has a first cylindrical portion (62a) and a second cylindrical portion (62b) formed in this order toward the air passage (19),
the second cylindrical portion (62b) is formed so that the cross-sectional area of the flow path is larger than the cross-sectional area of the flow path of the first cylindrical portion (62a);
The second opening (52) is formed in the second cylindrical portion (62b).

In the ninth aspect, pressure loss occurs when air flows from the second tubular portion (62b) to the first tubular portion (62a), reducing the total pressure. This reduces the dynamic pressure of the air flowing from the first tubular portion (62a) into the casing (50, 111), thereby reducing the wind speed.

A tenth aspect is any one of the fourth to ninth aspects,
The opening surface of the second opening (52) is formed to be inclined with respect to the air flow in the air passage (19), and includes a suppression portion (55) that suppresses the inflow of foreign matter contained in the air in the air passage (19).

In the tenth aspect, the opening area of the second opening (52) can be increased, allowing a large amount of air to be taken in. Furthermore, the suppression section (55) prevents foreign matter contained in the air from reaching the detection section (110a), thereby preventing false detection of the refrigerant and malfunction of the detection section (110a).

An eleventh aspect is any one of the first to tenth aspects,
The casing (50, 111) is provided with a second conveyor (130) for sucking air from the air passage (19) into the first opening (51).

In the eleventh aspect, the second conveyor (130) can forcefully draw air into the first opening (51). This allows the refrigerant-containing air that accumulates at the bottom of the air passage (19) to be conveyed to the refrigerant sensor (110).

A twelfth aspect is the eleventh aspect,
The first conveyor (30) has a first electric motor (30b) that drives the first conveyor (30),
the second conveyor (130) has a second electric motor (130a) that drives the second conveyor (130);
The first electric motor (30b) and the second electric motor (130a) are supplied with electric power from different power sources.

In the twelfth aspect, by connecting the second conveyor (130) and the first conveyor (30) to different power sources, the second conveyor (130) can be operated even when the first conveyor (30) is stopped, making it possible to detect refrigerant leaks.

A thirteenth aspect is the eleventh or twelfth aspect,
The second conveyor (130) sucks air at a height of 1 m or less from the bottom of the air passage (19) to the first opening (51).

In the thirteenth aspect, refrigerant that accumulates at a height of 1 m or less from the bottom surface of the air passage (19) can be detected.

A fourteenth aspect is any one of the eleventh to thirteenth aspects,
the casing (50, 111) has a third opening (73) through which air sucked into the first opening (51) is blown out into the air passage (19);
The third opening (73) is located at the same height as or lower than the first opening (51).

When the first conveyor (30) is operating, the pressure generated in the first opening (51) is equal to or higher than the pressure generated in the third opening (73) located downstream in the air flow. Therefore, the second conveyor (130) sucks air through the first opening (51), thereby reducing the operating load on the second conveyor (130).

A fifteenth aspect is any one of the first to fourteenth aspects,
The container (1) has a wall (16a) separating the external space (5) from the air passage (19),
The casing (50, 111) is provided on the wall (16a).

In the fourteenth aspect, maintenance of the detection unit (110a) can be performed from outside the container (1) without having to enter the container (1).

FIG. 1 is a perspective view of a container refrigeration unit according to an embodiment, as seen from the front. FIG. 2 is a vertical cross-sectional view of a container refrigeration unit. FIG. 3 is a piping diagram of a container refrigeration unit. FIG. 4 is a block diagram showing the relationship between the control unit of the container refrigeration unit and other devices. FIG. 5 is an enlarged view of the area enclosed by the dashed line in FIG. FIG. 6 is a vertical cross-sectional view corresponding to FIG. 5 of a container refrigeration unit according to Modification 1. In FIG. FIG. 7 is a vertical cross-sectional view corresponding to FIG. 2 of a container refrigeration unit according to Modification 2. As shown in FIG. FIG. 8 is an enlarged view of the area enclosed by the dashed line in FIG. FIG. 9 is a perspective view of a vertical cross section of a sensor casing according to the second modification. FIG. 10 is a vertical cross-sectional view corresponding to FIG. 2 of a container refrigeration unit according to Modification 3. As shown in FIG. FIG. 11 is a perspective view of a sensor casing according to the third modification. Fig. 12 is an enlarged view of the portion surrounded by the dashed line in Fig. 10. (A) is a view showing a cross section taken along the line A-A in Fig. 11. (B) is a view showing a cross section taken along the line B-B in Fig. 11.

Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are essentially preferred examples and are not intended to limit the scope of the present invention, its applications, or its uses. Furthermore, the configurations of the embodiments, variations, and other examples described below can be combined or partially substituted within the scope of the present invention.

(1) Overall Configuration of Container The container refrigeration system (10) is applied to a container (1). The overall configuration of the container (1) of this embodiment will be described with reference to Figures 1 to 3. In the following description, terms such as "front,""rear,""left,""right,""upper," and "lower" refer to the directions indicated by the arrows in Figure 1.

The container (1) is used for marine transportation. The container (1) is a refrigerated container that cools the air inside. The container (1) has a container body (2) and a container refrigeration unit (10). As shown in Figure 2, the interior of the container body (2) is divided into a storage space (3) and an air passage (19) that communicates with the storage space (3). The storage space (3) stores objects such as food and plants. The container refrigeration unit (10) cools the storage space (3). A front opening (4) is formed in the front of the container body (2). The container refrigeration unit (10) is attached to the container body (2) so as to close the front opening (4) of the container body (2).

(2) Container Refrigeration Unit The container refrigeration unit (10) has a container casing (11). The container casing (11) forms a lid for the front opening (4) of the container body (2). The container casing (11) has a casing body (12) and a partition plate (13). The casing body (12) separates the storage space (3) from an external space (5) that is the external space of the container body (2). The partition plate (13) is located on the back side (rear side) of the container casing (11).

The container refrigeration unit (10) includes a refrigerant circuit (R) that performs a refrigeration cycle. The container refrigeration unit (10) includes, as equipment located outside the container, a compressor (25), an external heat exchanger (26), and an external fan (27). The container refrigeration unit (10) includes, as equipment located inside the container, an internal heat exchanger (29) and an internal fan (30).

(2-1) Casing Body As shown in FIG. 2, the casing body (12) has a flat plate portion (12a) and a recessed portion (12b). The flat plate portion (12a) is formed on the upper part of the casing body (12) so as to be substantially flush with the front opening (4) of the container casing (11). As shown in FIG. 1, the flat plate portion (12a) is provided with an inspection window (22) and a ventilation device (40). The inspection window (22) is located on the right side of the flat plate portion (12a). The ventilation device (40) is located on the left side of the flat plate portion (12a). The inspection window (22) is a transparent window through which the interior of the casing body (12) can be seen. The ventilation device (40) ventilates the storage space (3).

The recess (12b) is formed in the lower part of the container casing (11). The recess (12b) is recessed rearward from the lower end of the flat plate portion (12a). An external storage space (14) is formed in front of the recess (12b). An internal storage space (15) is formed above the recess (12b) and between the flat plate portion (12a) and the partition plate (13). The lower end of the recess (12b) forms the bottom plate (12c). The bottom plate (12c) extends to both the left and right ends of the casing body (12).

The casing body (12) is constructed by stacking an external casing (16), an insulating layer (17), and an internal casing (18) in the thickness direction (front-to-back direction). The external casing (16) faces the external space (5). The internal casing (18) faces the interior of the refrigerator. As such, the recess (12b) has a side wall (16a) of the external casing (16) extending in the vertical direction and a side wall of the internal casing (18). The side wall (16a) of the external casing (16) extending in the vertical direction is an example of a wall portion (16a) separating the external space (5) and the air passage (19). The insulating layer (17) is provided between the external casing (16) and the internal casing (18). The external casing (16) is constructed of aluminum. The inner casing (18) is made of fiber-reinforced plastic (FRP). The heat insulating layer (17) is made of foamed resin.

(2-2) Partition Plate and Air Passage As shown in FIG. 2, the partition plate (13) is a plate-like member located behind the recess (12b). The partition plate (13) extends in the vertical direction so as to be spaced a predetermined distance from the rear surface of the recess (12b). An air passage (19) through which air flows inside the container is formed between the casing body (12) and the partition plate (13). An inlet (20) is formed between the upper end of the partition plate (13) and the upper wall (2a) of the container body (2). The inlet (20) connects the storage space (3) to the inlet end of the air passage (19). An outlet (21) is formed between the lower end of the partition plate (13) and the lower wall (2b) of the container body (2). The outlet (21) connects the storage space (3) to the outlet end of the air passage (19). Air flows in the vertical direction through the air passage (19). Specifically, air flows vertically through the air passage (19).

(2-3) Components of the External Space The external storage space (14) is provided with a compressor (25), an external heat exchanger (26), and an external fan (27). The compressor (25) is installed on the bottom plate (12c) of the container casing (11). The compressor (25) is disposed near the bottom of the external storage space (14). The compressor (25) is disposed near the right of the external storage space (14).

The external fan (27) is located near the top of the external storage space (14). The external fan (27) has an external fan body (27a) and an external fan motor (27b). The external fan body (27a) is a propeller fan. The external fan motor (27b) drives the external fan body (27a) when energized. As shown in FIG. 2, an external passage (28) through which outside air flows is formed on the back side of the external fan (27).

The external heat exchanger (26) is provided in the external storage space (14) at a height position between the external fan (27) and the compressor (25). The external heat exchanger (26) is located in the external passage (28). The external heat exchanger (26) is a fin-and-tube type heat exchanger.

(2-4) Components of the Internal Space An internal heat exchanger (29) and an internal fan (30) are provided in the air passage (19). Specifically, the internal heat exchanger (29) and the internal fan (30) are provided in the internal storage space (15), which is a part of the air passage (19). The internal heat exchanger (29) is supported by the container casing (11) so as to span the casing body (12) and the partition plate (13). The internal heat exchanger (29) is a fin-and-tube heat exchanger. The internal heat exchanger (29) is an example of a heat exchanger (29).

The internal fan (30) circulates air inside the container (1) between the storage space (3) and the air passage (19). The internal fan (30) has an internal fan body (30a) and an internal fan motor (30b). The internal fan body (30a) is a propeller fan. The internal fan motor (30b) drives the internal fan body (30a) when energized. The internal fan motor (30b) is an example of a first electric motor (30b).

(2-5) Refrigerant Circuit As shown in Fig. 3, the container refrigeration unit (10) has a refrigerant circuit (R). The refrigerant circuit (R) is filled with a refrigerant. The refrigerant circuit (R) performs a vapor compression refrigeration cycle by circulating the refrigerant.

The refrigerant in the refrigerant circuit (R) has a density greater than that of air. In this embodiment, 2,3,3,3-tetrafluoropropene (hereinafter sometimes referred to as R1234yf refrigerant or R1234yf) is used. The refrigerant may be difluoromethane (R32) or 1,3,3,3-tetrafluoropropene (R1234ze). The refrigerant may be a single refrigerant or a mixed refrigerant containing other refrigerants. The mixed refrigerant may be a refrigerant consisting of 2,3,3,3-tetrafluoropropene (R1234yf) and difluoromethane (R32). The mixed refrigerant may be a refrigerant (R454C) consisting of 78.5 wt% 2,3,3,3-tetrafluoropropene (R1234yf) and 21.5 wt% difluoromethane (R32). The refrigerant may be flammable. The flammable refrigerant may be a highly flammable natural refrigerant such as propane (R290), methane (R50), ethane (R170), butane (R600), or isobutane (R600a), or may be ammonia (R717).The refrigerant may also be a natural refrigerant such as carbon dioxide ( _CO2 ).

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

The compressor (25) compresses the refrigerant it draws in. The compressor (25) discharges the compressed refrigerant. A discharge pipe (32) is connected to the discharge portion of the compressor (25). A suction pipe (33) is connected to the suction portion of the compressor (25). An accumulator (34) is provided in the suction pipe (33). The accumulator (34) is a container for storing liquid refrigerant.

The external heat exchanger (26) exchanges heat between the refrigerant flowing therethrough and the external air. The gas end of the external heat exchanger (26) communicates with the discharge pipe (32). The liquid end of the external heat exchanger (26) is connected to the liquid end of the internal heat exchanger (29) via the liquid pipe (35). The external heat exchanger (26) functions as a radiator (condenser) in which the refrigerant radiates heat to the air.

The expansion valve (31) is provided in the liquid pipe (35). The expansion valve (31) reduces the pressure of high-pressure refrigerant to low-pressure refrigerant. The expansion valve (31) is an electronic expansion valve with an adjustable opening. A receiver (36) is provided in the liquid pipe (35) between the external heat exchanger (26) and the expansion valve (31). The receiver (36) is a container that stores excess refrigerant in the refrigerant circuit (R).

The internal heat exchanger (29) exchanges heat between the refrigerant flowing therethrough and the internal air. The gas end of the internal heat exchanger (29) communicates with the suction pipe (33). The internal heat exchanger (29) functions as an evaporator in which the refrigerant absorbs heat from the air.

The refrigerant circuit (R) has a bypass pipe (37). The inlet end of the bypass pipe (37) communicates with the discharge pipe (32), and the outlet end of the bypass pipe (37) communicates with the liquid pipe (35). The bypass pipe (37) sends the refrigerant discharged from the compressor (25) to the internal heat exchanger (29), bypassing the external heat exchanger (26).

The refrigerant circuit (R) is provided with a first valve (38) and a second valve (39). The first valve (38) is provided between the discharge side of the compressor (25) and the gas end of the external heat exchanger (26), and downstream of the connection portion of the bypass pipe (37). The second valve (39) is provided in the bypass pipe (37). The first valve (38) and the second valve (39) are configured as solenoid on-off valves. The first valve (38) and the second valve (39) may be flow control valves whose opening degree is adjustable.

(2-6) Operation The container refrigeration system (10) performs a cooling operation and a defrosting operation.

During cooling operation, a refrigeration cycle is performed in which refrigerant compressed by the compressor (25) condenses in the external heat exchanger (26), is decompressed by the expansion valve (31), and evaporates in the internal heat exchanger (29). Air flowing out of the storage space (3) into the air passage (19) is cooled by the internal heat exchanger (29), which functions as an evaporator. The cooled air is sent to the storage space (3) (see the arrow in Figure 2).

During defrosting operation, the refrigerant compressed by the compressor (25) flows through the bypass pipe (37) and into the internal heat exchanger (29). The frost on the surface of the internal heat exchanger (29) melts due to the heat of the refrigerant flowing inside the internal heat exchanger (29).

(3) Control Unit As shown in Figure 4, the container refrigeration system (10) includes a control unit (100). The control unit (100) controls the container refrigeration system (10). The control unit (100) includes a microprocessor, an electric circuit, and an electronic circuit. The microprocessor includes a CPU (Central Processing Unit), a memory, a communication interface, an analog input/output, and a contact input/output interface. The memory stores various programs to be executed by the CPU and data used by the programs.

The control unit (100) controls the mechanical elements of the container refrigeration unit (10). As shown in FIG. 4, this target value may be a value that can be arbitrarily set by a user of the container refrigeration unit (10) via the operation unit (101). The operation unit (101) is configured, for example, with a touch panel, remote controller, or dip switches provided on the container refrigeration unit (10). The operation unit (101) may also be a communications terminal connected to the container refrigeration unit (10) via a network. The target value does not necessarily have to be set by the user, and may be a value that is automatically determined by the control unit (100) depending on, for example, the operating mode and operating conditions.

(4) Refrigerant Sensor As shown in Figure 2, the container refrigeration system (10) includes a refrigerant sensor (110). The refrigerant sensor (110) detects refrigerant leaked from the refrigerant circuit (R) inside the container (1). Specifically, the refrigerant sensor (110) detects refrigerant contained in the air flowing through the air passage (19). Hereinafter, air containing leaked refrigerant and air not containing leaked refrigerant may be collectively referred to as air.

The refrigerant sensor (110) of this embodiment is a thermal conduction gas sensor. As shown in FIG. 5 , the refrigerant sensor (110) includes a housing (111), a detection element (110a), and a detection board (110b). The housing (111) accommodates the detection element (110a) and the detection board (110b). The housing (111) will be described in detail below. The detection element (110a) is an example of a detection unit (110a). The detection element (110a) detects the thermal conductivity of a gas, such as air or refrigerant gas. In this manner, the detection element (110a) detects refrigerant leaking into the container (1). The detection board (110b) detects the difference in thermal conductivity between the air and the refrigerant detected by the detection element (110a). The greater this difference in thermal conductivity, the higher the refrigerant concentration in the detected air. The detection board (110b) outputs a predetermined signal indicating the refrigerant concentration to the control unit (100).

(4-1) Sensor Casing As shown in FIG. 5, the container refrigeration system (10) of this embodiment includes a sensor casing (50) that houses the refrigerant sensor (110).

The sensor casing (50) is provided on the side wall of the external casing (16). Specifically, the sensor casing (50) is provided so as to penetrate the side wall (16a) of the external casing (16) and the side wall of the internal casing (18), which are aligned in the front-to-rear direction. The front surface of the sensor casing (50) is exposed to the external storage space (14), and the rear surface (56a) is exposed to the air passage (19). In other words, the front surface of the sensor casing (50) is exposed to the external space (5).

As shown in FIG. 2, the sensor casing (50) is positioned below the external heat exchanger (26). Preferably, the sensor casing (50) is positioned at the same height as the compressor (25) when viewed from the front of the external casing (16). More preferably, the sensor casing (50) is positioned at a height near the bottom plate (12c) when viewed from the front of the external casing (16). The sensor casing (50) may be positioned so as to be in contact with the bottom plate (12c).

The sensor casing (50) is disposed below the internal fan (30). The sensor casing (50) is disposed below the internal heat exchanger (29). The sensor casing (50) accommodates the refrigerant sensor (110), and therefore the detection element (110a) is disposed below the internal heat exchanger (29).

As shown in FIG. 5, the sensor casing (50) has a main body (56) and a lid (57). The main body (56) is formed in a box shape that is open at the front. The main body (56) has a first flange (56b) for fixing the lid (57). The first flange (56b) is formed so as to extend outward from the edge of the opening on the front surface of the main body (56).

The main body portion (56) has a first insertion hole (58). The first insertion hole (58) is formed in the rear surface (56a) of the main body portion (56). The first insertion hole (58) connects the inside of the main body portion (56) with the air passage (19). The first insertion hole (58) is a hole through which a second storage portion (111b) of the housing (111), described below, is inserted.

The lid portion (57) is a plate-like member formed in a generally rectangular shape. The lid portion (57) closes the opening on the front surface of the main body portion (56). The lid portion (57) contacts the first flange portion (56b). The lid portion (57) and the main body portion (56) are fixed to each other by inserting a fastening member, a bolt (90), through the lid portion (57) and the first flange portion (56b). When the sensor casing (50) is attached to the casing main body (12), the rear surface (56a) of the main body portion (56) is exposed within the air passage (19). When the sensor casing (50) is attached to the casing main body (12), the lid portion (57) is exposed to the external storage space (14).

(4-2) Housing The housing (111) has a first housing portion (111a) that houses the detection board (110b) and a second housing portion (111b) that houses the detection element (110a) and the filter (112).

The first storage section (111a) is formed in a flat box shape. The first storage section (111a) is disposed in the space within the main body section (56). Specifically, the first storage section (111a) is disposed within the main body section (56) toward the rear surface (56a).

The second accommodating portion (111b) is formed in a cylindrical shape. The second accommodating portion (111b) extends from the first accommodating portion (111a) toward the inside of the air passage (19). Specifically, the second accommodating portion (111b) passes through the first insertion hole (58) from the first accommodating portion (111a) and extends horizontally toward the air passage (19). The tip portion of the second accommodating portion (111b) protrudes into the air passage (19). A first opening (51) is formed at the tip of the second accommodating portion (111b). The first opening (51) connects the detecting element (110a) and the air passage (19). In this embodiment, the sensor casing (50) and the housing (111) correspond to the casings (11, 50) of the present disclosure.

The first opening (51) opens in the horizontal direction (the direction of the dashed-dotted arrow in Figure 5). "The first opening (51) faces the horizontal direction" means that the opening surface of the first opening (51) is not inclined relative to the horizontal direction. Also, "The first opening (51) faces the horizontal direction" means that the opening surface of the first opening (51) is formed in a plane perpendicular to the horizontal direction (vertical plane).

The first opening (51) opens in a direction perpendicular to the air flow in the air passage (19). The phrase "the first opening (51) is perpendicular to the air flow in the air passage (19)" means that the opening surface of the first opening (51) is formed along the air flow and is not inclined relative to the direction of the air flow. The phrase "the first opening (51) is perpendicular to the air flow in the air passage (19)" means that the opening surface of the first opening (51) faces neither upstream nor downstream of the air flow.

The filter (112) and the detection element (110a) are arranged in this order within the second storage section (111b) from the first opening (51) toward the first storage section (111a). The filter (112) is arranged near the first opening (51), and the detection element (110a) is arranged near the first storage section (111a). This allows the filter (112) to capture dust contained in the air flowing from the air passage (19) into the first opening (51).

(4-3) Air Flow in the Air Passage While the internal fan (30) is operating, an airflow flows from top to bottom in the air passage (19) (in the direction of the solid arrow in FIG. 5 ). For example, refrigerant leaking from the internal heat exchanger (29) mixes with air passing through the internal heat exchanger (29) and flows through the air passage (19). Because the first opening (51) is opened perpendicular to the air passage (19), a portion of the air containing refrigerant flows into the first opening (51) of the refrigerant sensor (110) and comes into contact with the detection element (110a). In this way, refrigerant leaked into the air can be detected while the internal fan (30) is operating.

While the internal fan (30) is stopped, no airflow is generated in the air passage (19) by the internal fan (30). In this case, refrigerant leaking from the internal heat exchanger (29) accumulates at the bottom of the interior of the compartment and then gradually diffuses upward (in the direction of the dashed arrow in FIG. 5 ). At this time, because the first opening (51) is open in a direction perpendicular to the air passage (19), the air containing the refrigerant flows gradually upward from the bottom through the air passage (19), flows into the first opening (51), and comes into contact with the detection element (110a).

(5) Features (5-1) Feature 1
The container refrigeration system (10) of this embodiment is disposed below the internal heat exchanger (29) and includes a detection element (110a) (detection unit (110a)) that detects refrigerant leaking into the container (1), a housing (111) that accommodates the detection element (110a), and a sensor casing (50) (casing (111, 50)). The housing (111) has a first opening (51) that connects the detection element (110a) to the air passage (19), and the first opening (51) opens horizontally when viewed from the air passage (19) side.

In this embodiment, the first opening (51) opens horizontally. This makes it easier for leaked refrigerant that has accumulated in the lower part of the container (1) to enter the first opening (51) as it diffuses upward when the first conveyor (30) is stopped. This reduces the time it takes for the detection element (110a) to detect leaked refrigerant inside the container (1), enabling relatively rapid detection of leaked refrigerant.

(5-2) Feature 2
In the container refrigeration unit (10) of this embodiment, the first opening (51) opens in a direction perpendicular to the air flow in the air passage (19).

When the pressure acting on the detection element (110a) increases due to the air flowing through the air passage (19), the detection element (110a) is more likely to erroneously detect the presence of refrigerant. In contrast, in this embodiment, the first opening (51) is open in a direction perpendicular to the air flow through the air passage (19), thereby suppressing the pressure acting on the first opening (51). This makes it possible to suppress erroneous detection of the presence of refrigerant.

(5-3) Feature 3
In this embodiment, the sensor casing (50) is provided on the side wall (16a) of the external casing (16), thereby enabling maintenance of the refrigerant sensor (110) from outside the container (1) without entering the container (1).

(6) Modifications Modifications of the above embodiment will be described below. Configurations that differ from the above embodiment will be described below.

(6-1) Modification 1
As shown in FIG. 6 , the container refrigeration unit (10) of the first modification includes a windbreak plate (120). The windbreak plate (120) is an example of a pressure reducer (120). The windbreak plate (120) is disposed in the air passage (19) above the first opening (51). In the air passage (19), an airflow is generated from above to below by the internal fan (30). The windbreak plate (120) is a plate member that blocks the flow of air toward the first opening (51). In other words, the windbreak plate (120) is a plate member that blocks a portion of the flow of air toward the first opening (51). In yet another way, the windbreak plate (120) is a plate member that suppresses the dynamic pressure acting on the first opening (51) due to the airflow.

Specifically, the windbreak plate (120) is erected rearward from the rear surface (56a) of the sensor casing (50) so that the tip of the second housing portion (111b) is hidden when viewed from above the air passage (19). The windbreak plate (120) is installed so that its plate surface is perpendicular or oblique to the longitudinal direction of the air passage (19) or the direction of the airflow. In other words, the windbreak plate (120) is not installed so that its plate surface is parallel to the longitudinal direction of the air passage (19) or the direction of the airflow.

The windbreak plate (120) should be located in a position that suppresses the dynamic pressure acting on the first opening (51). Considering the lack of influence of the airflow on the first opening (51), it is preferable that the windbreak plate (120) be located as close to the first opening (51) as possible.

The windbreak plate (120) may have any shape as long as it suppresses the dynamic pressure acting on the first opening (51). Considering the resistance to the airflow at the first opening (51), the larger the surface area of the windbreak plate (120) is, the more preferable it is, as long as it does not obstruct the airflow in the air passage (19).

When part of the air flowing through the air passage (19) comes into contact with the windbreak plate (120), the speed of the air is reduced. As a result, the speed of the air between the windbreak plate (120) and the first opening (51) is lower than the speed of the air around it. In this way, the dynamic pressure on the first opening (51) is reduced. In this way, the windbreak plate (120) is disposed in the air passage (19) and reduces the pressure acting on the first opening (51) by the air conveyed by the first conveyor (30).

(6-2) Modification 2
As shown in Figures 7 to 9, the sensor casing (50) of Modification 2 has a different configuration from the sensor casing (50) of the above-described embodiment. In Modification 2, the sensor casing (50) corresponds to the casing (50) of the present disclosure. In the sensor casing (50) of Modification 2, the main body (56) is disposed inside the external casing (16). Specifically, the main body (56) of the sensor casing (50) is fixed to the side wall (16a) of the external casing (16).

The lid portion (57) of the sensor casing (50) of Modification 2 is formed in the shape of a rectangular tray. The lid portion (57) has a fixing plate (57a) that fixes the refrigerant sensor (110) and a peripheral wall (57b) that stands from the outer periphery of the fixing plate (57a) toward the main body portion (56). The lid portion (57) and the main body portion (56) are fixed to each other by fastening members (not shown).

In Modification 2, the refrigerant sensor (110) is arranged so that its entirety is housed within the sensor casing (50). Specifically, the first housing portion (111a) of the housing (111) is fixed to the fixing plate (57a). The first housing portion (111a) is arranged toward the center of the fixing plate (57a). The second housing portion (111b) of the housing (111) is housed within the main body portion (56) so that its tip faces the air passage (19).

As shown in FIG. 9, the main body portion (56) of Modification 2 has a second flange portion (56c), an attachment portion (59), a first ventilation member (61), a second ventilation member (62), and a receiving portion (53).

The second flange portion (56c) is a portion that is fixed to the external casing (16). Specifically, the second flange portion (56c) is formed so as to extend to both the left and right sides of the rear surface (56a) of the main body portion (56). Mounting holes (H) are formed in the second flange portion (56c). The sensor casing (50) is fixed to the external casing (16) by inserting fastening members (not shown) such as bolts through the mounting holes (H) and the side wall (16a) of the external casing (16).

As shown in Figures 8 and 9, the mounting portion (59) is an area where the first ventilation member (61) is attached. The mounting portion (59) is formed in the lower part of the rear surface (56a). The mounting portion (59) is formed to be recessed. A first communication hole (81) is formed in the mounting portion (59). The first communication hole (81) is a circular opening that connects the interior of the main body portion (56) with the first ventilation member (61). The first communication hole (81) is formed so as to contact the lower end of the rear surface (56a).

A second communication hole (82) is formed in the rear surface (56a) of the main body portion (56). The second communication hole (82) is an opening into which one end of the second ventilation member (62) is inserted. The second communication hole (82) is formed in the upper part of the rear surface (56a). The second communication hole (82) is an elongated hole extending in the left-right direction. Gaps are formed between the second communication hole (82) and the second ventilation member (62). These gaps are formed below and on the left and right sides of the second ventilation member (62).

The first ventilation member (61) and the second ventilation member (62) are cylindrical. Both ends of the first ventilation member (61) and the second ventilation member (62) are open. The first ventilation member (61) and the second ventilation member (62) communicate the internal space of the main body portion (56) with the air passage (19). The first ventilation member (61) and the second ventilation member (62) supply air taken in from the air passage (19) to the refrigerant sensor (110) in the main body portion (56), and discharge the air taken in by the main body portion (56) back into the air passage (19). The first ventilation member (61) and the second ventilation member (62) extend from the rear surface (56a) of the main body portion (56) toward the air passage (19). Specifically, the first ventilation member (61) and the second ventilation member (62) are provided so as to penetrate the side wall of the internal casing (18) and the side wall of the external casing (16) that are adjacent in the front-to-rear direction.

The first ventilation member (61) extends obliquely downward from the lower part of the rear surface (56a) of the main body (56) toward the air passage (19). In other words, the first ventilation member (61) extends toward the downstream side of the air flow in the air passage (19) when the internal fan (30) is operating.

One end of the first ventilation member (61) opens toward the refrigerant sensor (110) located inside the main body (56). The opening at one end of the first ventilation member (61) communicates with the first communication hole (81). One end of the first ventilation member (61) is fixed to the mounting portion (59). Specifically, a disk-shaped third flange portion (61a) is formed at one end of the first ventilation member (61), and the third flange portion (61a) comes into contact with the mounting portion (59), thereby fixing the first ventilation member (61) to the main body (56).

The opening at the other end of the first ventilation member (61) corresponds to the first opening (51). The first opening (51) faces the air passage (19). The first opening (51) opens in the horizontal direction. Specifically, the opening surface of the first opening (51) is formed so as to be a vertical plane. In other words, the opening surface of the first opening (51) is formed so as to follow the air flow in the air passage (19).

The second ventilation member (62) is an example of a tubular portion (62). The second ventilation member (62) has a first tubular portion (62a) and a second tubular portion (62b) formed in this order from the main body portion (56) toward the air passage (19).

The first cylindrical portion (62a) extends obliquely upward from the upper part of the rear surface (56a) of the main body portion (56) toward the air passage (19). One end of the first cylindrical portion (62a) is inserted into the second communication hole (82). One end of the first cylindrical portion (62a) is disposed inside the main body portion (56). One end of the first cylindrical portion (62a) opens toward the refrigerant sensor (110) inside the main body portion (56). One end of the first cylindrical portion (62a) is disposed so as to contact the upper edge of the second communication hole (82).

The second cylindrical portion (62b) is connected to the first cylindrical portion (62a). The second cylindrical portion (62b) is formed so that its flow path cross-sectional area is larger than that of the first cylindrical portion (62a). The flow path cross-sectional area is the opening area formed in a cross section perpendicular to the cylindrical axis direction. The second cylindrical portion (62b) extends upward along the inner surface of the side wall of the internal casing (18), which forms the inner surface of the air passage (19). In other words, the second cylindrical portion (62b) extends vertically upward through the air passage (19) from one end of the first cylindrical portion (62a). As shown in FIG. 8 , the lower portion of the side surface of the second cylindrical portion (62b) extending in the vertical direction, which is on the partition plate (13) side, is curved and connects to the first cylindrical portion (62a). This curved shape makes it easier for air passing through the second cylindrical portion (62b) to be guided to the first cylindrical portion (62a).

A second opening (52) is formed at one end of the second tubular portion (62b). The second opening (52) opens toward the upstream side of the air flow in the air passage (19). The second opening (52) faces upward within the air passage (19). In this manner, the sensor casing (50) has the second opening (52). The second opening (52) connects the detection element (110a) to the air passage (19). The second ventilation member (62) has the second opening (52) and connects to the detection element (110a).

The second opening (52) is located below the internal heat exchanger (29). That is, the second opening (52) is located below the internal fan (30). Since the first opening (51) is located below the second opening (52), the first opening (51) and the second opening (52) are located below the internal fan (30).

The second opening (52) is formed so that its opening surface is inclined with respect to the air flow in the air passage (19). Specifically, as shown in Figures 7 and 8, in the vertical cross section of the air passage (19), the second cylindrical portion (62b) is closer to the side wall of the internal casing (18) than to the partition plate (13) in the air passage (19), and the opening surface of the second opening (52) inclines downward from the side wall of the internal casing (18) toward the partition plate (13). In other words, the second opening (52) is formed so that, in the vertical cross section of the air passage (19), the angle formed between the opening surface of the second opening (52) and the side wall of the internal casing (18) of the air passage (19) is an obtuse angle.

A filter portion (55) is formed on the opening surface of the second opening portion (52). The filter portion (55) prevents foreign matter contained in the air flowing through the air passage (19) from entering the second ventilation member (62). The filter portion (55) is formed in a mesh shape. The filter portion (55) is an example of a suppression portion (55).

As shown in Figures 8 and 9, the receiving portion (53) is located between the second opening (52) and the detection element (110a) and receives water that has flowed from the air passage (19) into the second opening (52). Specifically, the receiving portion (53) receives water contained in air that flows into the second ventilation member (62) through the second opening (52). The receiving portion (53) extends from the lower portion of the opening edge of the second communication hole (82) toward the inside of the main body portion (56). The receiving portion (53) is formed in a bowl shape so as to receive water that flows into the main body portion (56) from one end of the second ventilation member (62).

The receiving portion (53) is provided so as to cross between one end of the second ventilation member (62) and the refrigerant sensor (110). In other words, the receiving portion (53) is provided so as to cross the shortest path between one end of the second ventilation member (62) and the tip of the second housing portion (111b) of the refrigerant sensor (110).

A discharge port (54) is formed in the receiving portion (53). The discharge port (54) discharges water adhering to the receiving portion (53) downward into the main body portion (56). The discharge port (54) is formed in the shape of a slit extending in the front-to-rear direction. Multiple discharge ports (54) may be formed.

Water discharged from the outlet (54) falls downward within the main body (56). The falling water passes through the first communication hole (81), the first ventilation member (61), and is discharged into the air passage (19). In this way, the outlet (54) discharges water that has flowed from the air passage (19) into the second opening (52) between the second opening (52) and the detection element (110a) to the outside.

When the internal fan (30) is operating, part of the air flowing from the top to the bottom of the air passage (19) flows into the second ventilation member (62) through the second opening (52). When the air passing through the second cylindrical portion (62b) flows into the first cylindrical portion (62a), which is narrower than the second cylindrical portion (62b), a pressure loss occurs in the air, and the total pressure decreases.

The air flowing from the first tubular portion (62a) into the main body portion (56) is blown out into a space wider than the opening of the first tubular portion (62a), and therefore the wind speed is reduced. This reduces the wind speed of the air flowing through the main body portion (56). In particular, the receiving portion (53) disposed between the opening of the second ventilation member (62) and the refrigerant sensor (110) blocks the airflow blowing out from the opening of the second ventilation member (62) toward the refrigerant sensor (110), thereby reducing the dynamic pressure generated at the tip of the second accommodation portion (111b) that accommodates the detection element (110a).

When a portion of the air in the main body portion (56) flows into the second storage portion (111b), the detection element (110a) comes into contact with this air. This allows the refrigerant concentration in the air to be detected. The air flowing through the main body portion (56) flows into the first ventilation member (61) through the first communication hole (81) and is discharged from the first opening (51) to the air passage (19).

Suppose that refrigerant begins to leak from around the internal heat exchanger (29) while the internal fan (30) is stopped. The refrigerant accumulates at the bottom of the container (1) and gradually diffuses upward within the container. Because the first opening (51) opens horizontally, some of the refrigerant-containing air diffusing from bottom to top in the air passage (19) flows into the first opening (51). Because the first ventilation member (61) extends upward from the air passage (19) toward the main body (56), the air that flows into the first opening (51) passes through the first ventilation member (61) and flows into the main body (56). The refrigerant-containing air also rises within the main body (56). During this process, the air that flows into the second storage section (111b) comes into contact with the detection element of the second storage section (111b), thereby detecting the refrigerant concentration. Air in the main body (56) flows through the second ventilation member (62) via the second communication hole (82) and flows out from the second opening (52) into the air passage (19).

In Modification 2, the sensor casing (50) has a second ventilation member (62) that communicates with the main body portion (56). The inner diameter of the second ventilation member (62) is relatively small, which reduces the wind speed of the air flowing from the second ventilation member (62) into the main body portion (56). This reduces the pressure acting on the detection element (110a) of the refrigerant sensor (110), thereby reducing erroneous detection of the refrigerant.

In Modification 2, the second ventilation member (62) has a first tubular portion (62a) and a second tubular portion (62b). Because the cross-sectional flow area of the first tubular portion (62a) is smaller than that of the second tubular portion (62b), pressure loss occurs when air flows from the second tubular portion (62b) into the first tubular portion (62a), resulting in a decrease in total pressure. This decrease in total pressure reduces the dynamic pressure when air flows from the first tubular portion (62a) into the main body portion (56), which is a relatively large space, and thus reduces the air velocity. Specifically, if the tubular portion (62) were composed only of the second tubular portion (62b) without the first tubular portion (62a), the pressure loss of the air passing through the tubular portion (62) would be reduced, thereby suppressing a decrease in total pressure. As a result, the dynamic pressure of the air flowing into the main body portion (56) is less likely to be reduced. However, in this example, the total pressure of the air flowing from the second cylindrical portion (62b) to the first cylindrical portion (62a) is reduced, and therefore the dynamic pressure of the air flowing into the main body portion (56) can be reduced accordingly.

In variant 2, the second opening (52) opens toward the upstream side of the air flow in the air passage (19). Therefore, while the internal fan (30) is operating, air can be easily taken in through the second opening (52) by utilizing the dynamic pressure of the air flow. Furthermore, while the internal fan (30) is stopped, air can be easily taken in through the first opening (51) by utilizing the natural diffusion of air. In this way, the time from when a refrigerant leak occurs to when it is detected can be shortened both when the internal fan (30) is operating and when it is stopped.

In Modification 2, the first opening (51) and the second opening (52) are positioned below the internal fan (30). As a result, by being positioned below the internal fan (30) in the air passage (19), the wind pressure acting on the second opening (52) increases, making it easier for the second opening (52) to take in air.

In Modification 2, the second opening (52) is formed so that its opening surface is inclined with respect to the air flow in the air passage (19). The area of the opening surface of the second opening (52) can be increased, making it possible to take in a large amount of air flowing through the air passage (19). Because the opening surface of the second opening (52) is inclined downward from the internal casing (18) toward the partition plate (13), it is possible to reduce the ventilation resistance of the air flowing through the air passage (19).

In the second modification, a suppression portion (55) is formed on the opening surface of the second opening (52). This prevents foreign matter contained in the air from coming into contact with the detection element (110a), thereby preventing malfunction of the detection element (110a) and false detection of the refrigerant.

In Modification 2, the receiving portion (53) is provided so as to cross between the second communication hole (82) and the refrigerant sensor (110). The receiving portion (53) prevents water from splashing into the main body (56) and prevents water from adhering to the refrigerant sensor (110). The receiving portion (53) also prevents air flowing into the main body (56) from the second ventilation member (62) from directly hitting the refrigerant sensor (110). This reduces the dynamic pressure acting on the detection element (110a). In this way, the receiving portion (53) prevents the refrigerant sensor (110) from malfunctioning or erroneously detecting the refrigerant.

In the second modification, an outlet (54) is formed in the receiving portion (53). This allows water that has flowed into the main body portion (56) together with air from the second ventilation member (62) to be discharged to the outside of the main body portion (56).

(6-3) Modification 3
As shown in Figures 10 to 12, the sensor casing (50) of Modification 3 has a different configuration from the sensor casing (50) of the above-described embodiment and each of the above-described modifications. In Modification 3, the sensor casing (50) corresponds to the casing (50) of the present disclosure. In the sensor casing (50) of Modification 3, the main body (56) is disposed inside the external casing (16). Specifically, the main body (56) of the sensor casing (50) is fixed to the sidewall of the external casing (16).

The sensor casing (50) has a main body portion (56) and a closing portion (74). The main body portion (56) of this modified example is formed in a box shape with an open rear end. In other words, the rear surface of the main body portion (56) is open over substantially the entire area. The closing portion (74) covers the opening on the rear surface of the main body portion (56). The closing portion (74) is fixed to the main body portion (56). Specifically, a fourth flange portion (56d) is formed on the edge of the opening of the main body portion (56), and a bolt (90), which is a fastening member, is inserted between the closing portion (74) and the fourth flange portion (56d).

As shown in FIG. 12 , a refrigerant sensor (110) is disposed within the main body (56). The refrigerant sensor (110) is fixed to the front wall of the main body (56). The refrigerant sensor (110) is provided at a position through which air flowing within the main body (56) passes. Air flowing within the second main body (56) comes into contact with the detection element (110a) within the second storage portion (111b).

As shown in FIG. 11 , the sensor casing (50) has a third ventilation member (63) and a fourth ventilation member (64). The third ventilation member (63) and the fourth ventilation member (64) are cylindrical members. The third ventilation member (63) and the fourth ventilation member (64) communicate between the inside of the main body portion (56) and the air passage (19). The third ventilation member (63) and the fourth ventilation member (64) are formed in the closing portion (74).

The third ventilation member (63) extends generally horizontally from the lower part of the closing portion (74) toward the air passage (19), and then extends downward within the air passage (19). Specifically, the third ventilation member (63) extends horizontally from the lower end of the main body portion (56), penetrates the side walls of the external casing (16) and the internal casing (18), which are aligned in the front-to-rear direction, and then extends downward from the underside of the air passage (19) to a predetermined height position.

The opening at the end of the third ventilation member (63) faces downward. The opening at the end of the third ventilation member (63) corresponds to the third opening (73) of the present disclosure. The third opening (73) faces downstream in the air flow when the internal fan (30) is operating.

A guard portion (75) is provided at the third opening (73). The guard portion (75) has a large number of pores formed therein. This prevents dust and other foreign matter from entering the third ventilation member (63).

The fourth ventilation member (64) extends generally horizontally from the upper portion of the closing portion (74) toward the air passage (19) and then extends downward within the air passage (19). Specifically, the fourth ventilation member (64) has a large-diameter portion (64a) and a small-diameter portion (64b). The large-diameter portion (64a) is provided at the upper portion of the closing portion (74) and extends horizontally. The inner diameter of the large-diameter portion (64a) is larger than the inner diameters of the small-diameter portion (64b) and the third ventilation member (63). The large-diameter portion (64a) penetrates the side wall of the external casing (16) and the side wall of the internal casing (18), which are aligned in the front-to-rear direction. The small-diameter portion (64b) is continuous with the large-diameter portion (64a). The small-diameter portion (64b) extends downward within the air passage (19). In this modified example, the opening at the end of the small diameter portion (64b) corresponds to the first opening portion (51).

The first opening (51) opens downward. The first opening (51) opens downstream of the air flow when the internal fan (30) is operating. This prevents water dropping from the internal heat exchanger (29) from flowing into the third opening (73).

A guard portion (75) is provided at the first opening (51). The guard portion (75) prevents foreign matter such as dust from entering the fourth ventilation member (64).

In this modified example, the first opening (51) is provided at a height of 1 m from the bottom surface of the air passage (19). The first opening (51) is located above the third opening (73). In other words, the third opening (73) is located below the first opening (51).

As shown in FIG. 12 , the container refrigeration unit (10) of Modification 3 includes a suction fan (130). The suction fan (130) is an example of a second conveyor (130). The suction fan (130) draws air from the air passage (19) into the first opening (51).

The suction fan (130) is provided in the sensor casing (50). Specifically, the suction fan (130) is provided in a portion of the main body (56) where the large diameter portion (64a) is connected. When the suction fan (130) is operating, an airflow is formed in the main body (56) from the fourth ventilation member (64) to the third ventilation member (63). The suction fan (130) has a suction fan body (130b) and a suction fan motor (130a).

The suction fan body (130b) is a propeller fan. The size of the suction fan body (130b) is smaller than the size of the large diameter portion (64a). Specifically, the diameter of the suction fan body (130b) is smaller than the inner diameter of the large diameter portion (64a). By making the diameter of the suction fan body (130b) larger than the inner diameter of the large diameter portion (64a) in this way, it is possible to reduce pressure loss when the suction fan (130) draws in air.

The suction fan motor (130a) drives a fan when energized. The suction fan motor (130a) is connected to a power supply different from the power supply that supplies power to the internal fan motor (30b). In this way, power is supplied to the internal fan motor (30b) and the suction fan motor (130a) from different power supplies. The second power supply may be a replaceable battery, such as a cell.

In this modified example, the suction fan (130) draws air at a height of 1 m or less from the bottom of the air passage (19) to the first opening (51). Next, the wind speed of the suction fan (130) in this example will be described.

When the weight (kg·m/s ² ) of the fluid resisting the suction force is W and the suction force (kg·m/s ² ) of the suction fan (130) is F _fan , the relationship W=F _fan holds. Using this relationship, the wind speed of the suction fan (130) can be calculated. Specifically, W and F _fan are expressed by the following equations (1) and (2), respectively.

ρ _air : density of air (kg/m ³ ), ρ _yf : density of R1234yf refrigerant (kg/m ³ ), g: gravitational acceleration (m/s ² ), A: cross-sectional area (m ² ), h: height to lift the fluid (m)
Based on equations (1), (2) and Q=A×v _air , v _air can be expressed by equation (3).

The density of air (ρ _air ) can be calculated based on the molecular weight of dry air, the molecular weight of water vapor, the gas constant, temperature, saturated water vapor pressure, atmospheric pressure, and relative humidity. The density of 1234yf refrigerant (ρ _yf ) can be calculated based on the molecular weight of the refrigerant, the gas constant, temperature, and atmospheric pressure. When the air density is ρ _air = 0.65 kg/m ³ , the minimum required air velocity for the suction fan (130) to lift the fluid 1 cm can be expressed by equation (4).

When the density of R1234yf is ρ _yf =3.95 kg/m ³ , the minimum required air velocity when the suction fan ( 130 ) lifts the fluid 1 cm is v _air =0.703 m/s based on equation (4).

Since the first opening (51) is located at a height of 1 m from the bottom surface of the air passage (19), the wind speed required for the suction fan (130) to suck in the fluid located 1 m below the first opening (51) can be expressed by equation (5) by substituting h = 1 m into equation (3).

When the density of R1234yf is ρ _yf =3.95 kg/m ³ , the required air velocity when the suction fan ( 130 ) sucks in the fluid 1 m below is v _air =7.03 m/s based on equation (5).

In this way, by setting the air velocity of the suction fan (130) to 7.03 m/s or more, the air containing refrigerant that has accumulated at the bottom of the air passage (19) can be sucked up to the refrigerant sensor (110), thereby shortening the time from when a refrigerant leak occurs to when the refrigerant is detected, and allowing the refrigerant leak to be detected relatively quickly.

The air flow in the air passage (19) in this example will be explained. The suction fan (130) is assumed to be constantly operating, whether the internal fan (30) is operating or not.

As shown in FIG. 12(B), while the internal fan (30) is operating, a portion of the air flowing downward through the air passage (19) is drawn into the fourth ventilation member (64) through the first opening (51) by the suction fan (130). The air drawn into the fourth ventilation member (64) flows into the main body (56) and then flows through the main body (56) toward the third ventilation member (63). A portion of the air flowing through the main body (56) flows into the second housing portion (111b) of the refrigerant sensor (110) and comes into contact with the detection element (110a). This allows the refrigerant sensor (110) to detect the refrigerant contained in the air. The air that has flowed into the third ventilation member (63) is discharged into the air passage (19) through the third opening (73). In this way, the third opening (73) blows the air drawn into the first opening (51) into the air passage (19). When the internal fan (30) is stopped, air is sucked in through the first opening (51) by the suction fan (130), flows into the main body (56), flows toward the third ventilation member (63), and is discharged through the third opening (73) into the air passage (19).

In the third modification, the suction fan (130) transports the internal air to the refrigerant sensor (110). This allows for relatively rapid detection of leaking refrigerant without waiting for the refrigerant in the air passage (19) to diffuse upward while the internal fan (30) is stopped, as in the above-described embodiment and modifications.

In Modification 3, the suction fan motor (130a) is supplied with power from a power source different from that of the internal fan motor (30b). This allows the suction fan (130) to operate even if the power supply to the internal fan (30) is interrupted due to, for example, a malfunction. This allows refrigerant leaking into the internal compartment to be detected by operating the suction fan (130) even when the internal fan (30) is stopped.

In Modification 3, by setting the air velocity of the suction fan (130) to 7.03 m/s or more while the internal fan (30) is stopped, the refrigerant accumulating on the bottom of the interior of the container (1) can be forcibly sucked into the first opening (51) by the suction fan (130).

In the third modification, the first opening (51) is located above the third opening (73). Therefore, the pressure acting on the third opening (73), which is closer to the internal fan (30), is higher than the pressure acting on the first opening (51). The suction fan (130) can draw air through the first opening (51), which has a higher pressure, and blow the air out through the third opening (73), which has a lower pressure. If the first opening (51) were located below the third opening (73), the suction fan (130) would have to direct air from the first opening (51), which has a lower pressure, to the third opening (73), which has a higher pressure, resulting in a higher operating load. However, in this embodiment, the increase in the operating load of the suction fan (130) due to the pressure difference between the first opening (51) and the third opening (73) can be suppressed. Furthermore, if the first opening (51) is located relatively close to the third opening (73), there is a risk that the air discharged from the third opening (73) will be sucked into the first opening (51). Therefore, it is preferable that the third opening (73) be located away from the first opening (51).

(7) Other Embodiments The above-described embodiment and each of the above-described modifications may be configured as follows.

In the above embodiment and variants 1 and 2, the first opening (51) may face downward rather than horizontally. Specifically, the first opening (51) may be formed so that at least a portion of its opening surface is inclined downward. For example, the first opening (51) may have the entire opening surface inclined downward, or may have a portion of the opening surface formed downward and the remaining portion formed perpendicular to the horizontal.

In the above embodiment and the above variants 1 and 2, the first opening (51) may face downstream of the air flow in the air passage (19) when the internal fan (30) is operating. Specifically, the first opening (51) may be formed so that at least a portion of its opening surface is inclined toward the downstream side of the air flow in the air passage (19). For example, the first opening (51) may have the entire opening surface inclined toward the downstream side of the air flow in the air passage (19), or may be formed so that a portion of the opening surface is formed toward the downstream side of the air flow and the remaining portion is parallel to the air flow.

In the above embodiment and variant 1, even if the direction of air flow in the air passage (19) is inclined with respect to the vertical direction, the first opening (51) only needs to open in the horizontal direction. Furthermore, in the above embodiment and variant 1, even if the direction of air flow in the air passage (19) is inclined with respect to the vertical direction, the first opening (51) only needs to open in a direction perpendicular to the air flow or downstream.

In the above embodiment, the sensor casing (50) and the housing (111) may be integrally formed.

In the above-described first variant, the windshield (120) only needs to be disposed in the air passage (19), and does not necessarily have to be formed in the sensor casing (50).

In the above-described second modification, the sensor casing (50) does not have to have a receiving portion (53). Furthermore, if the sensor casing (50) is provided with a receiving portion (53), it need not be provided in the second communication hole (82) as long as it can receive water flowing into the main body portion (56) from one end of the second ventilation member (62).

In the above-described second variation, the sensor casing (50) does not have to have an outlet (54). Furthermore, if an outlet (54) is provided in the sensor casing (50), it is sufficient that the outlet (54) can discharge water that flows into the main body portion (56) to the outside of the main body portion (56), and it does not have to be provided in the receiver portion (53).

In the above-described second modification, the sensor casing (50) only needs to have the second opening (52), and does not necessarily need to have the second ventilation member (62).

In the above-described second modification, the second ventilation member (62) may be formed with a cylindrical portion having a flow path cross-sectional area different from that of the first cylindrical portion (62a) and the second cylindrical portion (62b). Furthermore, the second ventilation member (62) need only be formed in a cylindrical shape, and may not have the first cylindrical portion (62a) and the second cylindrical portion (62b). For example, the inner surface of the second ventilation member (62) may be formed in a tapered shape so that the diameter decreases from the second opening (52) toward the main body portion (56).

In the above-described second modification, the filter portion (55) may be formed integrally with the second ventilation member (62) or may be separate. The second opening (52) only needs to be formed to prevent foreign matter from entering, and the second opening (52) may have a structure that prevents foreign matter from entering.

In the above-described second modification, the sensor casing (50) may have the main body (56), the first ventilation member (61), and the second ventilation member (62) integrally formed.

In the above-described third modification, the sensor casing (50) may be configured such that the closing portion (74), the third ventilation member (63), and the fourth ventilation member (64) are integrally formed.

In the above-mentioned variant example 3, the first opening (51) may be located at a height of 1 m or less from the bottom surface of the air passage (19), for example, at a height of 0.2 m, 0.4 m, 0.6 m, or 0.8 m.

In the third modification, the first opening (51) and the third opening (73) may be at the same height. Specifically, the opening surfaces of the first opening (51) and the third opening (73) may be at the same height.

In the third modification, the refrigerant may be R32, R744 (CO ₂ ), R290 (propane), or R454C. In the case of R32, when the refrigerant density ρ is 1.80 kg/m ³ , the minimum required air velocity v _air for the internal fan (30) to lift air 1 cm is 0.415 m/s. Therefore, when the first opening (51) is located 1 m above the bottom of the air passage (19), the required air velocity v _air for drawing air from the bottom of the air passage (19) to the refrigerant sensor (110) is 4.15 m/s based on _equation (5). Similarly, in the case of R744 (CO ₂ ), when the refrigerant density ρ is 1.52 kg/m ³ , the minimum required air velocity v _air is 0.362 m/s, and the required air velocity v _air is 3.62 m/s. In the case of R290 (propane), the refrigerant density ρ = 1.53 kg/m ³ , the required minimum air speed v _air = 0.362 m/s, and the required air speed v _air is 3.62 m/s. In the case of R454C, the refrigerant density ρ = 3.144 kg/m ³ , the required minimum air speed v _air = 0.612 m/s, and the required air speed v _air is 6.12 m/s.

Although the embodiments and modifications have been described above, it will be understood that various changes in form and details are possible without departing from the spirit and scope of the claims. Furthermore, the above embodiments and modifications may be combined or substituted as appropriate as long as the functionality of the subject matter of this disclosure is not impaired. The terms "first," "second," etc., described above, are used to distinguish the terms to which these terms are attached, and do not limit the number or order of those terms.

As described above, the present disclosure is useful for container refrigeration systems.

1 container
3. Containment space
5 Outside space
10 Container refrigeration equipment
16a Side wall (wall)
19 Air passage
29 Internal heat exchanger (heat exchanger)
30 In-storage fan (first conveyor)
30b First electric motor (interior fan motor)
50 Sensor casing (casing)
51 First opening
52 Second opening
53 Receiving part
54 Outlet
55 Suppression section (filter section)
62 Cylinder portion (second ventilation member)
62a First cylindrical part
62b Second cylinder part
73 Third Opening
110a Detecting unit (detecting element)
111 Housing (casing)
120 Pressure reduction section (windbreak plate)
130 Second conveyor (suction fan)
130a Second electric motor (suction fan motor)
R Refrigerant circuit

Claims (13)

A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
the casing (50, 111) has a first opening (51) and a second opening (52) that connect the detection portion (110a) and the air passage (19);
The first opening (51) opens in a horizontal direction or downward from the horizontal direction,
the second opening (52) opens toward the upstream side of the air flow in the air passage (19),
the first conveyor (30) is disposed in the air passage (19);
the first opening (51) and the second opening (52) are disposed below the first conveyor (30) ;
The density of the refrigerant is greater than the density of air.
Refrigeration equipment for containers. A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
The air passage (19) is formed by the first conveyor (30) so that air flows from above to below,
the casing (50, 111) has a first opening (51) and a second opening (52) that connect the detection portion (110a) and the air passage (19);
the first opening (51) opens in a direction perpendicular to the air flow in the air passage (19) or toward the downstream side of the air flow,
the second opening (52) opens toward the upstream side of the air flow in the air passage (19),
the first conveyor (30) is disposed in the air passage (19);
the first opening (51) and the second opening (52) are disposed below the first conveyor (30) ;
The density of the refrigerant is greater than the density of air.
Refrigeration equipment for containers. 3. The container refrigeration system according to claim 1, further comprising a pressure reducing section (120) arranged in the air passage (19) for reducing a pressure acting on the first opening (51) by air transported by the first conveyer (30). 3. The container refrigeration device according to claim 1, wherein the casing (50, 111) has a receiving portion (53) between the second opening (52) and the detection portion (110a) for receiving water that has flowed from the air passage (19) into the second opening ( 52 ). 3. The container refrigeration device according to claim 1, wherein the casing (50, 111) has a discharge port (54) between the second opening (52) and the detection portion (110a) for discharging water that has flowed from the air passage (19) into the second opening (52) to the outside. 3. The container refrigeration system according to claim 1 , wherein the casing (50, 111) has a cylindrical portion (62) in which the second opening (52) is formed and which communicates with the detection portion (110a). The cylindrical portion (62) has a first cylindrical portion (62a) and a second cylindrical portion (62b) formed in this order toward the air passage (19),
the second cylindrical portion (62b) is formed so that the cross-sectional area of the flow path is larger than the cross-sectional area of the flow path of the first cylindrical portion (62a);
7. The container refrigeration system according to claim 6 , wherein the second opening (52) is formed in the second cylindrical portion (62b). 3. The container refrigeration system according to claim 1, wherein an opening surface of the second opening (52) is formed so as to be inclined with respect to the air flow in the air passage (19), and the system is provided with a suppression section (55) that suppresses the inflow of foreign matter contained in the air in the air passage (19 ). A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
the casing (50, 111) has a first opening (51) that connects the detection portion (110a) to the air passage (19), and a third opening (73) that blows air sucked into the first opening (51) into the air passage (19),
The first opening (51) opens in a horizontal direction or downward from the horizontal direction,
the third opening (73) is disposed at the same height as or lower than the first opening (51); the casing (50, 111) is provided with a second conveyor (130) that sucks air from the air passage (19) into the first opening (51) ;
The density of the refrigerant is greater than the density of air.
Refrigeration equipment for containers. A container refrigeration unit provided in a container (1) having a refrigerant circuit (R) that performs a refrigeration cycle, the container (1) having an interior partitioned into an accommodation space (3) and an air passage (19) communicating with the accommodation space (3),
a first conveyor (30) for circulating the air inside the container (1) between the storage space (3) and the air passage (19);
a heat exchanger (29) disposed in the air passage (19);
a detector (110a) disposed below the heat exchanger (29) and configured to detect refrigerant leaking into the container (1);
a casing (50, 111) that houses the detection part (110a),
The air passage (19) is formed by the first conveyor (30) so that air flows from above to below,
the casing (50, 111) has a first opening (51) that connects the detection portion (110a) to the air passage (19), and a third opening (73) that blows air sucked into the first opening (51) into the air passage (19),
the first opening (51) opens in a direction perpendicular to the air flow in the air passage (19) or toward the downstream side of the air flow,
the third opening (73) is disposed at the same height as or lower than the first opening (51);
The casing (50, 111) is provided with a second conveyor (130) that sucks air from the air passage (19) into the first opening (51) ,
The density of the refrigerant is greater than the density of air.
Refrigeration equipment for containers. The first conveyor (30) has a first electric motor (30b) that drives the first conveyor (30),
the second conveyor (130) has a second electric motor (130a) that drives the second conveyor (130);
11. The container refrigeration system according to claim 9 or 10 , wherein the first electric motor (30b) and the second electric motor (130a) are supplied with electric power from different power sources. 11. The container refrigeration system according to claim 9, wherein the second conveyor (130) draws air at a height from a bottom surface of the air passage (19) to the first opening (51) of 1 m or less. The container (1) has a wall (16a) separating the external space (5) from the air passage (19),
Container refrigeration system according to claim 1, 2, 9 or 10 , wherein the casing (50, 111) is mounted on the wall (16a).