WO2019065856A1 - Refrigeration device - Google Patents

Abstract

One main pipe (77) connected to a liquid line (60) and having an expansion valve (78), and multiple branch pipes (81a, 81b, 81c) branching off from the outflow end of the main pipe (77) to connect to compressors (13a, 13b, 13c) and each having a flow adjustment valve (82a, 82b, 82c) are provided in an injection circuit (81). A control unit (100) is provided which, during an injection operation, maintains at a prescribed fixed opening degree the flow adjustment valves (82a, 82b, 82c) corresponding to prescribed compressors (13a, 13b, 13c) of the multiple compressors (13a, 13b, 13c), and adjusts the opening degrees of the compression valve (78) and the remaining flow adjustment valves (82a, 82b, 82c).

Description

Refrigeration system

The present invention relates to a refrigeration system.

Conventionally, a refrigeration system provided with a refrigerant circuit is known.

The refrigeration system disclosed in Patent Document 1 is configured to perform air conditioning in the room with the air conditioning unit and to perform refrigeration / refrigeration in the cold storage with the cold installation unit. A plurality of compressors, a heat source side heat exchanger, and a plurality of use side heat exchangers are connected to the refrigeration system. The plurality of compressors include an air conditioning side compressor corresponding to the air conditioning unit and a cooling side compressor corresponding to the cooling unit. The plurality of usage-side heat exchangers include an indoor heat exchanger of the air conditioning unit and a refrigeration heat exchanger of the cooling unit. In a cooling operation with a refrigeration system, the refrigerant is condensed in the heat source side heat exchanger, and at the same time, a refrigeration cycle in which the indoor heat exchanger and the cold storage heat exchanger become the evaporator is performed.

Specifically, in the cooling operation, the refrigerant compressed by the plurality of compressors is condensed by the heat source side heat exchanger, and is then sent to the indoor heat exchanger and the refrigeration heat exchanger. In the indoor heat exchanger, the refrigerant absorbs heat from indoor air and evaporates. The refrigerant evaporated in the indoor heat exchanger is drawn into the air-conditioning side compressor and compressed again. In the refrigeration heat exchanger, the refrigerant absorbs heat from the air in the storage and evaporates. The refrigerant evaporated in the refrigeration heat exchanger is sucked into the refrigeration side compressor and compressed again.

In this cooling operation, the evaporation temperature or the evaporation pressure of the refrigerant in the indoor heat exchanger becomes higher than the evaporation temperature or the evaporation pressure of the refrigerant in the cold storage heat exchanger. In other words, the suction pressure of the air-conditioning side compressor that sucks the refrigerant of the indoor heat exchanger is higher than the suction pressure of the cooling-side compressor that sucks the refrigerant of the cold storage heat exchanger.

Moreover, the injection circuit for introduce | transducing a refrigerant | coolant (liquid refrigerant) into several compressors is connected to the refrigerant circuit of the freezing apparatus of the literature. The injection circuit has one main pipe connected to the liquid line, and a plurality of branch pipes branched from the main pipe and connected to the plurality of compressors. In the cooling operation described above, an injection operation of introducing the refrigerant into each compressor is performed. In this injection operation, the refrigerant having flowed through the main pipe is branched to each branch pipe and then introduced into the middle portion (during compression) of each compressor. Thereby, it can suppress that the temperature of the discharge refrigerant | coolant of each compressor becomes high excessively.

JP, 2004-044921, A

In the injection circuit of the refrigeration system disclosed in Patent Document 1, a flow control valve is connected to the main pipe, and an expansion valve is connected to each branch pipe. In this configuration, the amount of refrigerant introduced into each compressor can be individually adjusted by adjusting the opening degree of the flow control valve and each expansion valve in the injection operation.

However, fine adjustment of the opening degree of all of the flow control valve and the plurality of expansion valves in this way complicates control of the valve in the injection operation. As a result, due to the control of each valve, there is a possibility that a problem such as hunting of the temperature of the discharged refrigerant may occur.

The present invention has been made by focusing on such problems, and is to simplify valve control in the injection operation.

The first aspect is a refrigerant in which a plurality of compressors (13a, 13b, 13c), at least one radiator (12), and at least one evaporator (22, 32) are connected, and a refrigeration cycle is performed. The present invention is directed to a refrigeration system provided with a circuit (2), and the refrigerant circuit (2) includes a refrigerant in a liquid line (60) between the radiator (12) and the evaporator (22, 32). An injection circuit (81) for performing an injection operation to be introduced into the compressor (13a, 13b, 13c) is connected, and the injection circuit (81) is connected to the liquid line (60) and an expansion valve (78). And one main pipe (77) having a branch) from the outlet end of the main pipe (77) to be respectively connected to the plurality of compressors (13a, 13b, 13c), each having a flow control valve (82a, 82b, 82c) and a plurality of branch pipes (81a, 81b, 81c) are provided. Maintaining a flow control valve (82a, 82b, 82c) corresponding to a predetermined compressor (13a, 13b, 13c) among the plurality of compressors (13a, 13b, 13c) at a predetermined fixed opening degree, A control unit (100) is provided to adjust the opening degree of the expansion valve (78) and the remaining flow control valves (82a, 82b, 82c).

In the first aspect, the injection operation is performed in the refrigeration cycle. In this injection operation, a flow rate control valve (a) is connected to a branch pipe (81a, 81b, 81c) corresponding to a predetermined compressor (13a, 13b, 13c) of the plurality of compressors (13a, 13b, 13c). 82a, 82b, 82c) are maintained at a predetermined fixed opening. Therefore, it is not necessary to appropriately adjust or control the opening degree of the flow rate control valve (82a, 82b, 82c).

On the other hand, the opening degree of the expansion valve (78) and the opening degree of the remaining flow control valves (82a, 82b, 82c) are adjusted so as to adjust the temperatures of the refrigerant discharged from the compressors (13a, 13b, 13c). It is adjusted. That is, even if the opening degree of the flow rate control valve (82a, 82b, 82c) corresponding to a certain compressor (13a, 13b, 13c) is maintained at the fixed opening degree, the expansion valve (78) of the main pipe (77) is opened. By adjusting the degree, the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) can be adjusted. On the other hand, by adjusting the opening degree of the remaining flow rate control valves (82a, 82b, 82c), the discharge of the compressor (13a, 13b, 13c) corresponding to the remaining flow rate control valves (82a, 82b, 82c) The temperature of the refrigerant can also be adjusted. Therefore, in the control according to the present invention, the number of valves to be controlled can be substantially reduced as compared with the conventional method, and valve control can be simplified.

In the second aspect, in the first aspect, the control unit (100) corresponds to the flow control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant. Is maintained at the predetermined fixed opening degree.

In the second aspect, in the injection operation, the opening degree of the flow rate adjusting valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant is maintained at the fixed opening degree. . The compressor (13a, 13b, 13c) having the highest discharge temperature among the plurality of compressors (13a, 13b, 13c) needs to introduce a liquid refrigerant. Therefore, the opening degree of the flow rate adjusting valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the maximum temperature of the discharged refrigerant is opened at the fixed opening degree. Thus, the refrigerant can be reliably introduced into the compressors (13a, 13b, 13c). On the other hand, the adjustment of the discharge temperature of the compressor (13a, 13b, 13c) is performed by the expansion valve (78). Further, the flow rate control valves (82a, 82b, 82c) corresponding to the compressors (13a, 13b, 13c) in which the temperature of the discharged refrigerant is not maximum individually adjust the opening degree without fixing the opening degree.

According to a third aspect, in the second aspect, the controller (100) is a flow control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant. It is a freezing device characterized by maintaining the above-mentioned predetermined opening to the maximum.

In the third aspect, in the injection operation, the opening degree of the flow rate adjusting valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant is maintained at the maximum opening degree. . The compressor (13a, 13b, 13c) having the highest discharge temperature among the plurality of compressors (13a, 13b, 13c) needs to introduce a large amount of liquid refrigerant. For this reason, the opening degree of the flow rate control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) in which the temperature of the discharged refrigerant is maximum is taken as the maximum opening degree. Thereby, the temperature of the refrigerant discharged to the compressors (13a, 13b, 13c) can be rapidly reduced. Further, the flow rate control valves (82a, 82b, 82c) corresponding to the compressors (13a, 13b, 13c) in which the temperature of the discharged refrigerant is not maximum individually adjust the degree of opening. The refrigerant whose flow rate is adjusted by the expansion valve (78) and the flow rate control valves (82a, 82b, 82c) is introduced into the compressor (13a, 13b, 13c) in which the temperature of the discharged refrigerant is not maximum.

By the control as described above, a relatively large amount of refrigerant can be introduced into the compressor (13a, 13b, 13c) in which the temperature of the discharge refrigerant is maximum. Conversely, a relatively small amount of refrigerant can be produced in the compressors (13a, 13b, 13c) in which the temperature of the discharged refrigerant is not maximum. Therefore, the temperature of the refrigerant discharged from each of the compressors (13a, 13b, 13c) can be quickly brought close to the optimum range.

According to a fourth aspect, in any one of the first to third aspects, in the refrigerant circuit (2), the refrigerants evaporated at different evaporation pressures of the plurality of evaporators (22, 32) are different in the compressor (13a, 13a, 13b, 13c) is characterized in that a refrigeration cycle is performed, which is inhaled respectively.

The fifth aspect is characterized in that one evaporator (22) is connected to the refrigerant circuit (2) in any one of the first to third aspects.

According to the present invention, the expansion valve (78) and the remaining flow control valves (82a, 82a, 82c, 82c) are fixedly opened while the flow control valves (82a, 82b, 82c) corresponding to certain compressors (13a, 13b, 13c) have fixed openings. By adjusting the opening degree of 82b, 82c), the temperature of the refrigerant discharged from each compressor (13a, 13b, 13c) can be brought close to the target temperature while substantially reducing the number of valves to be controlled. . Thereby, the control of the injection operation can be simplified. In addition, it is possible to prevent the temperature of the refrigerant discharged from each compressor (13a, 13b, 13c) from hunting by finely adjusting the valve opening degree.

FIG. 1 is a refrigerant circuit diagram of a refrigeration apparatus according to an embodiment of the present invention. FIG. 2 is a view showing a refrigerant flow during cooling and cooling operation in the refrigeration system of FIG. FIG. 3 is a diagram showing the flow of the refrigerant during the first heating and cooling operation in the refrigeration system of FIG. FIG. 4 is a diagram showing a refrigerant flow during the second heating and cooling operation in the refrigeration system of FIG. FIG. 5 is a diagram showing the flow of the refrigerant during the third heating and cooling operation in the refrigeration system of FIG. FIG. 6 is a diagram showing a flow of refrigerant that defrosts the refrigeration heat exchanger in the reverse cycle during cooling in the refrigeration system of FIG. 1. FIG. 7 is a diagram showing the flow of refrigerant that defrosts the refrigeration heat exchanger in the reverse cycle during heating in the refrigeration system of FIG. 1. FIG. 8 is a block diagram showing a schematic configuration of a controller of the embodiment. FIG. 9 is a flow chart for explaining control of three expansion valves in the injection operation. FIG. 10 is a flow chart for explaining control of the flow control valve in the injection movement. FIG. 11 is a refrigerant circuit diagram of a refrigeration apparatus according to a modification of the embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. The following embodiments are essentially preferred examples, and are not intended to limit the scope of the present invention, its applications, or its applications.

<< Embodiment of the Invention >>
<Schematic Configuration of Refrigeration System>
The refrigeration system (1) according to the embodiment is provided in a cold storage warehouse and an office adjacent thereto, and performs refrigeration of goods and air conditioning of the room.

As shown in FIG. 1, the refrigeration system (1) comprises an outdoor unit (10) installed outdoors, an indoor unit (20) for air conditioning the indoor space, and a refrigeration unit (30) for cooling the inside of the cold storage warehouse. And a controller (100). The number of the indoor units (20) and the refrigeration unit (30) is not limited to one, and may be two or more. Then, these units are connected to constitute a refrigerant circuit (2). The refrigerant circuit (2) is roughly divided into an air conditioning system circuit (2a) for air conditioning the room, and a cooling system circuit for cooling the inside of the cold storage unit (30) and the freezing unit (40). And (2b) are formed.

The outdoor unit (10) is provided with an outdoor circuit (11) as a heat source side circuit having an outdoor heat exchanger (12). The indoor unit (20) is provided with an indoor circuit (21) (use side circuit) having an indoor heat exchanger (22). The refrigeration unit (30) is provided with a refrigeration circuit (31) (use-side circuit) having a refrigeration heat exchanger (32).

In the refrigeration system (1), the outdoor circuit (11) and the plurality of use side circuits (21, 31) are the first gas side communication pipe (51), the first liquid side communication pipe (52), the second gas side communication The refrigerant circuit (2) is connected to each other by four connecting pipes (51 to 54) including the pipe (53) and the second liquid side connecting pipe (54), and a refrigerant circuit (2) performing a vapor compression refrigeration cycle is configured. .

One end of the first gas side connection pipe (51) is connected to the first gas side closing valve (71) of the outdoor circuit (11), and the other end is connected to the gas side end of the indoor circuit (21). One end of the first liquid side communication pipe (52) is connected to the first liquid side closing valve (72) of the outdoor circuit (11), and the other end is connected to the liquid side end of the indoor circuit (21). One end of the second gas side communication pipe (53) is connected to the second gas side closing valve (73) of the outdoor circuit (11), and the other end is connected to the gas side end of the refrigeration circuit (31) . One end of the second liquid side communication pipe (54) is connected to the second liquid side closing valve (74) of the outdoor circuit (11), and the other end is connected to the liquid side end of the refrigeration circuit (31) .

<Outdoor unit>
The outdoor unit (10) is installed outdoors, and has the outdoor circuit (11) and an outdoor casing (10a) accommodating the outdoor circuit (11). The outdoor circuit (11) includes the outdoor heat exchanger (12), a compression mechanism (13), an outdoor expansion valve (14) (expansion mechanism), a receiver (15), and an oil separator (16). The first, second and third four-way selector valves (17, 18, 19) (switching mechanism) and the above-mentioned four closing valves (71, 72, 73, 74) are provided.

The compression mechanism (13) has first to third compressors (13a, 13b, 13c). The first to third compressors (13a, 13b, 13c) are all hermetic scroll compressors in which a fixed scroll and a movable scroll are engaged to form a compression chamber. In the first to third compressors (13a, 13b, 13c), suction ports (not shown) are opened at the suction positions of the compression chambers, and discharge ports (not shown) are open at the discharge positions. A port (not shown) is open.

The first compressor (cooling side compressor) (13a) and the third compressor (air conditioning side compressor) (13c) are variable displacement compressors. That is, the rotational speeds of the first compressor (13a) and the third compressor (13c) are configured to be variable by inverter control. On the other hand, the second compressor (13b) is a fixed displacement compressor having a constant rotational speed, and is mainly used for assisting the first compressor (13a), but for assisting the third compressor (13c) It can also be used for The second compressor (13b) may be a variable displacement compressor. In addition, a suction pipe (55) is connected to the suction side of the first to third compressors (13a, 13b, 13c), and a discharge pipe (56) is connected to the discharge side. The discharge pipe (56) is provided with a high pressure switch (110) for urgently stopping the compressor (13a, 13b, 13c) under abnormal high pressure.

The inflow side of the suction pipe (55) branches into a first inflow branch pipe (55a) and a second inflow branch pipe (55b). The first inflow branch pipe (55a) is connected to the second gas side shut-off valve (73) via the third four-way selector valve (19), while the second inflow branch pipe (55b) is connected to the second four path It is connected to the second port (P2) of the switching valve (18). The first inflow branch pipe (55a) and the second inflow branch pipe (55b) are connected to each other by the inflow communication pipe (66), and the third communication compressor (air conditioning side compressor) is connected to the inflow communication pipe (66). A pressure control valve (67) (flow rate control valve) is provided which can adjust the amount of refrigerant drawn in (13c) and the amount of refrigerant drawn in the first compressor (cooling side compressor) (13a).

The suction pipe (55) has a first outflow branch pipe (55c) (first suction branch pipe), a second outflow branch pipe (55d) (second suction branch pipe), and a third outflow branch pipe (55e) on the outflow side. ) (The third suction branch pipe). The first outflow branch pipe (55c) is connected to the suction side end of the first compressor (13a), and the second outflow branch pipe (55d) is connected to the suction side end of the second compressor (13b), The third outflow branch pipe (55e) is connected to the suction side end of the third compressor (13c).

The inflow side of the discharge pipe (56) branches into a first inflow branch pipe (56a), a second inflow branch pipe (56b), and a third inflow branch pipe (56c). The first inflow branch pipe (56a) is connected to the discharge side end of the first compressor (13a), and the second inflow branch pipe (56b) is connected to the discharge side end of the second compressor (13b), The third inflow branch pipe (56c) is connected to the discharge side end of the third compressor (13c). The first to third inflow branch pipes (56a, 56b, 56c) are respectively provided with check valves (CV1, CV2, CV3). These check valves (CV1, CV2, CV3) allow the refrigerant to flow from the first to third compressors (13a, 13b, 13c) to the four-way selector valve (17, 18, 19), Prevent the flow of refrigerant in the direction. The discharge pipe (56) has an outflow side branched into a first outflow branch pipe (56d), a second outflow branch pipe (56e), and a third outflow branch pipe (56f). The first outflow branch pipe (56d) is connected to the first port (P1) of the first four-way selector valve (17), and the second outflow branch pipe (56e) is connected to the first one of the second four-way selector valve (18). The third outflow branch pipe (56f) is connected to the port (P1), and is connected to the first port (P1) of the third four-way selector valve (19).

The oil separator (16) is provided in the middle of the discharge pipe (56). The oil separator (16) separates the lubricating oil mixed with the refrigerant discharged from the first to third compressors (13a, 13b, 13c), and the lubricating oil is separated from the first to third compressors (13a, 13a, 13c). Return to 13b, 13c). Specifically, the lubricating oil separated from the refrigerant in the oil separator (16) is introduced into the inflow end of an injection pipe (81) described later via an oil return pipe (50) connected to the oil separator (16). It will be returned to the side. The oil return pipe (50) is provided with a flow control valve (48).

The first, second and third four-way selector valves (17, 18, 19) communicate the first port (P1) with the third port (P3) and the second port (P2) with the fourth port (P4). And the first port (P1) communicates with the fourth port (P4) and the second port (P2) communicates with the third port (P3). Switching to the second state (indicated by the broken line in FIG. 1). The refrigeration system can perform various operations by the switching operation of the first, second and third four-way selector valves (17, 18, 19).

A first outflow branch pipe (56d) is connected to a first port (P1) of the first four-way selector valve (17). The second port (P2) of the first four-way selector valve (17) is connected to the third port (P3) of the second four-way selector valve (18). The third port (P3) of the first four-way selector valve (17) is connected to the first gas side shut-off valve (71) via a refrigerant pipe. The fourth port (P4) of the first four-way selector valve (17) is connected to the gas side end of the outdoor heat exchanger (12) via the outdoor gas pipe (58).

A second outflow branch pipe (56e) is connected to a first port (P1) of the second four-way selector valve (18). The second port (P2) of the second four-way selector valve (18) is connected to the second inflow branch pipe (55b) as described above. The third port (P3) of the second four-way selector valve (18) is connected to the second port (P2) of the first four-way selector valve (17) as described above. The fourth port (P4) of the second four-way selector valve (18) is a closed port that is closed.

A third outflow branch pipe (56f) is connected to a first port (P1) of the third four-way selector valve (19). The second port (P2) of the third four-way selector valve (19) is connected to the first inflow branch pipe (55a). The third port (P3) of the third four-way selector valve (19) is a refrigerant inflow pipe to the receiver (15) via the connection pipe (65) provided with the on-off valve (64). It is connected to the four liquid pipe (79), and the fourth port (P4) of the third four-way selector valve (19) is connected to the second gas side closing valve (73) via the refrigerant pipe.

The outdoor heat exchanger (12) is a fin-and-tube type heat exchanger, and an outdoor fan (12a) is provided in the vicinity. In the outdoor heat exchanger (12), heat exchange is performed between the refrigerant flowing inside and the outside air blown by the outdoor fan (12a). The outdoor fan (12a) is accommodated in the outdoor casing (10a) together with the outdoor circuit (11).

The outdoor heat exchanger (12) has a liquid side end connected to the top of the receiver (15) via a first liquid pipe (59). The bottom of the receiver (15) is provided with a freeze protection pipe (57) at the bottom of the outdoor heat exchanger (12) and a subcooling heat exchanger (76) connected to the freeze protection pipe (57). It is connected to the second liquid side shut-off valve (74) via the two liquid pipe (60). Further, a portion of the second liquid pipe (60) between the antifreeze pipe (57) and the subcooling heat exchanger (76) is connected to the first liquid side shut-off valve (72) through the third liquid pipe (62). )It is connected to the.

An outdoor expansion valve (14) is provided in the first liquid pipe (59). The outdoor expansion valve (14) is configured by an electronic expansion valve whose opening degree can be adjusted.

The first liquid pipe (59) and the third liquid pipe (62) are provided with check valves (CV4, CV5), respectively. The check valve (CV4) of the first liquid pipe (59) allows the refrigerant to flow from the outdoor heat exchanger (12) to the top of the receiver (15) and prevents the refrigerant from flowing in the reverse direction. The check valve (CV5) of the third liquid pipe (60) allows the refrigerant to flow from the antifreeze pipe (57) toward the first liquid side shut-off valve (72) and prevents the refrigerant from flowing in the reverse direction Do.

A bypass pipe (61) is provided between the first liquid pipe (59) and the second liquid pipe (60). One end of the bypass pipe (61) is connected to the upstream side of the check valve (CV4) in the first liquid pipe (59), and the other end is upstream of the check valve (CV9) in the second liquid pipe (60). It is connected to the. The bypass pipe (61) is provided with a check valve (CV8) to allow the flow of the refrigerant toward the outdoor heat exchanger (12) and to prohibit the flow of the refrigerant in the reverse direction. Between the bypass pipe (61) and the second liquid side shut-off valve (74), allow the flow of the refrigerant from the bypass pipe (61) to the second liquid side shut-off valve (74). A check valve (CV9) for inhibiting the flow of

The subcooling heat exchanger (76) includes a high pressure side flow passage (76a) and a low pressure side flow passage (76b). In the subcooling heat exchanger (76), the refrigerant flowing in the high pressure side flow passage (76a) and the low pressure side flow passage (76b) exchanges heat so that the refrigerant in the high pressure side flow passage (76a) is supercooled. It is configured. The low pressure side flow passage (76b) constitutes a part of a main pipe (77) of an injection pipe (81) which will be described in detail later.

A fourth liquid pipe (79) is provided between the downstream side of the check valve (CV5) of the second liquid pipe (60) and the downstream side of the check valve (CV4) of the first liquid pipe (59) It is done. The fourth liquid pipe (79) is provided with a check valve (CV6). The check valve (CV6) allows the flow of the refrigerant from the second liquid pipe (60) to the first liquid pipe (59), and prevents the flow of the refrigerant in the reverse direction.

The outdoor circuit (11) is provided with a refrigerant return pipe (80) during reverse cycle defrost operation. One end of the refrigerant return pipe (80) is connected between the second liquid side closing valve (74) and the bypass pipe (61), and the other end is a first liquid pipe (59) in the fourth liquid pipe (79). And connection piping (65) are connected. The refrigerant return pipe (80) is provided with a check valve (CV10) which allows the flow of the refrigerant toward the receiver (15) and prohibits the flow of the refrigerant in the reverse direction.

The injection pipe (81) includes a main pipe (77) connected to the second liquid pipe (60) which is a liquid line, and three branch pipes (81a, 81b, 81c) branched from the outflow end of the main pipe (77) Have.

An expansion valve (78) is connected to the upstream side of the low pressure side flow passage (76b) of the main pipe (77). The expansion valve (78) is constituted by an electronic expansion valve whose opening degree is variable. The expansion valve (78) regulates the flow rate of the refrigerant flowing through the main pipe (77).

The three branch pipes are composed of a first branch pipe (81a), a second branch pipe (81b), and a third branch pipe (81c). The outflow end of each branch pipe (81a, 81b, 81c) is connected to each intermediate pressure port of the corresponding compressor (13a, 13b, 13c). Each intermediate pressure port communicates with each compression chamber of the corresponding compressor (13a, 13b, 13c). Specifically, the first branch pipe (81a) is connected to the intermediate pressure port of the first compressor (13a), and the second branch pipe (81b) is connected to the intermediate pressure port of the second compressor (13b) The third branch pipe (81c) is connected to the intermediate pressure port of the third compressor (13c).

The first flow control valve (82a) for the first branch pipe (81a), the second flow control valve (82b) for the second branch pipe (81b), and the third flow rate for the third branch pipe (81c) The control valves (82c) are connected respectively. Each flow rate control valve (82a, 82b, 82c) is constituted by an electronic expansion valve whose opening degree is variable. Each branch pipe (81a, 81b, 81c) constitutes an injection circuit for introducing a gas refrigerant from the subcooling heat exchanger (76) into the compression chamber at an intermediate pressure of each compressor (13a, 13b, 13c) .

Various sensors are provided in the outdoor circuit (11). For example, the discharge piping (56) includes discharge temperature sensors (111a, 111b, 111c) for detecting the temperatures of the refrigerant discharged from the compressors (13a, 13b, 13c), and the compressors (13a, 13b, 13c). And a discharge pressure sensor (112) for detecting the pressure of the discharge refrigerant. The discharge temperature sensors (111a, 111b, 111c) correspond to the first discharge temperature sensor (111a) corresponding to the first compressor (13a) and the second discharge temperature sensor (111) corresponding to the second compressor (13b). And 111b) and a third discharge temperature sensor (111c) corresponding to the third compressor (13c). The suction pipe (55) is provided with a suction temperature sensor (113) for detecting the temperature of the suction refrigerant of each of the compressors (13a, 13b, 13c). The suction pipe (55) includes a first suction pressure sensor (114a) for detecting the pressure of refrigerant drawn from the first compressor (13a) and the second compressor (13b), and a suction of the third compressor (13c). A second suction pressure sensor (114b) is provided to detect the pressure of the refrigerant.

In the vicinity of the outdoor heat exchanger (12), an outdoor temperature sensor (115) for detecting the outdoor air temperature outside the room is provided. A first temperature sensor (118) is provided at the liquid side end of the outdoor heat exchanger (12). The main pipe (77) is provided with an intermediate pressure sensor (117). Further, the second liquid pipe (60) is provided with a pressure sensor (119) for detecting the pressure of the receiver (15). The detection values of these sensors are input to a controller (100) described later.

<Indoor unit>
The indoor unit (20) is installed indoors and has an indoor circuit (21) and an indoor casing (20a) that accommodates the indoor circuit (21). The indoor circuit (21) has a gas side end connected to the first gas side communication pipe (51) and a liquid side end connected to the first liquid side communication pipe (52). The indoor heat exchanger (22) and the indoor expansion valve (23) (expansion mechanism) are provided in the indoor circuit (21) in order from the gas side end. The indoor heat exchanger (22) is constituted by a cross fin type fin-and-tube heat exchanger, and an indoor fan (22a) is provided in the vicinity. The indoor fan (22a) is housed in the indoor casing (20a) together with the indoor circuit (21). In the indoor heat exchanger (22), heat exchange is performed between the refrigerant flowing inside and the indoor air blown by the indoor fan (22a).

The indoor expansion valve (23) is constituted by an electronic expansion valve whose opening degree can be adjusted. In the vicinity of the indoor heat exchanger (22), an indoor temperature sensor (121) for detecting the temperature of the indoor air is provided. In the indoor circuit (21), a heat transfer pipe of the indoor heat exchanger (22) is provided with a second temperature sensor (122). Further, an evaporation temperature sensor (123) is provided in the vicinity of the gas side end of the indoor circuit (21).

<Colder unit>
The refrigeration unit (30) has the refrigeration circuit (31) and a refrigerator (30a) for accommodating the refrigeration circuit (31).

In the refrigeration circuit (31) of the refrigeration unit (30), the gas side end is connected to the first branch gas pipe (53a) of the second gas side communication pipe (53), and the liquid side end is the second liquid side communication pipe It is connected to the first branched liquid pipe (54a) of (54). The refrigeration circuit (31) is provided with a refrigeration heat exchanger (32) and a refrigeration expansion valve (33) (expansion mechanism) in this order from the gas side end. The cold storage heat exchanger (32) is constituted by a cross fin type fin-and-tube heat exchanger, and an internal fan (32a) is provided in the vicinity. The internal fan (32a) is housed in the refrigerator (30a) together with the circuit for refrigeration (31). In the refrigeration heat exchanger (32), heat exchange is performed between the refrigerant flowing inside and the air inside the refrigerator (30a) which the inside fan (32a) blows. The cold storage expansion valve (33) is constituted by an electronic expansion valve whose opening degree can be adjusted. Further, an in-compartment temperature sensor (131) for detecting the temperature of the in-compartment air is provided in the vicinity of the cold storage heat exchanger (32). Moreover, the evaporation temperature sensor (132) is provided in the heat transfer tube of the refrigeration heat exchanger (32). In addition, a gas temperature sensor (133) is provided in the vicinity of the gas side end of the refrigeration circuit (31).

<controller>
The controller (100) (control unit) is configured using a microcomputer and a memory device (specifically, a semiconductor memory) that stores software for operating the microcomputer. The controller (100) controls each device of the refrigeration system (1).

Each operation of the refrigeration system (1) is switched by control of each device by the controller (100). The refrigeration system (1) performs a cooling operation to cool the room with the indoor unit (20) and a heating operation to heat the room with the indoor unit (20).

In the cooling operation, the cooling operation includes cooling the room air by the indoor unit (20) and simultaneously cooling the air in the cold storage unit (30) and the freezing unit (40). The heating operation includes a first heating / cooling operation, a second heating / cooling operation, and a third heating / cooling operation. In the first heating / cooling operation, the outdoor heat exchanger (12) is substantially stopped and, at the same time, the inside air is cooled by the refrigeration unit (30). In the second heating and cooling operation, the outdoor heat exchanger (12) becomes a radiator (condenser) and simultaneously cools the air in the cold storage by the refrigeration unit (30). In the third heating and cooling operation, the outdoor heat exchanger (12) becomes an evaporator and at the same time, the refrigeration unit (30) cools the air in the cold storage.

Further, in the cooling operation and the heating operation, the defrosting operation for defrosting the refrigeration heat exchanger (32) of the refrigeration unit (30) is executed respectively.

As shown in FIG. 8, the controller (100) includes an input unit (101), an arithmetic unit (102), a determination unit (103), and an output unit (104).

A signal indicating the detection value of each sensor or the state of each device is input to the input unit (101). More specifically, in the input section (101) of the present embodiment, the detected value (discharge pressure (Pd)) of the discharge pressure sensor (112) and the detected value (first discharge) of the first discharge temperature sensor (111a) The refrigerant temperature (Td1), the detected value of the second discharge temperature sensor (111b) (second discharged refrigerant temperature (Td2)), and the detected value of the third discharged temperature sensor (111c) (third discharged refrigerant temperature (Td3) ) Is input. Further, in the input section (101), the detection value (first suction pressure (Ps1)) of the first suction pressure sensor (114a) and the detection value (second suction pressure (PS2) of the second suction pressure sensor (114b) And the detection value (injection pressure (PI)) of the pressure sensor (117) are input.

The calculation unit (102) obtains an index for adjusting the opening degree of the expansion valve (78) based on the detection value of each sensor. Specifically, the calculation unit (102) calculates the discharge refrigerant of each compressor (13a, 13b, 13c) based on the discharge refrigerant temperature (Td1, Td2, T3) and the saturation temperature of the discharge pressure (Pd). The degree of superheat (discharge superheat) is calculated.

The determination unit (103) compares each discharge refrigerant temperature (Td1, Td2, Td3), discharge superheat degree, and a predetermined set value, and the expansion valve (78) or each flow control valve (82a, 82b, 82c) Control the opening degree of

-Driving operation-
In the refrigeration system (1), each operation mode of the cooling / cooling operation, the first heating / cooling operation, the second heating / cooling operation, and the third heating / cooling operation is switched by switching the four-way switching valves (17, 18, 19). To be executed.

<Cooling cooling operation>
The cooling operation shown in FIG. 2 is an operation for cooling the indoor unit (20) and cooling the refrigeration unit (30). The controller (100) switches the first and second four-way selector valves (17, 18) to the second state, switches the third four-way selector valve (19) to the first state, and the outdoor expansion valve (14). It controls to a fully open state and adjusts the opening degree of a refrigeration expansion valve (33) and an indoor expansion valve (23) suitably. Further, the on-off valve (64) and the pressure control valve (67) are controlled to be fully closed.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) merges in the discharge pipe (56) and then the lubricating oil is separated in the oil separator (16), and the first four-way selector valve (17) and the outdoor gas pipe (58) to flow into the outdoor heat exchanger (12). In the outdoor heat exchanger (12), the refrigerant releases heat to the outdoor air and condenses. The liquid refrigerant condensed in the outdoor heat exchanger (12) flows into the receiver (15) through the first liquid pipe (59) and is stored in the receiver (15).

The liquid refrigerant stored in the receiver (15) flows out of the receiver (15) and passes through the antifreeze pipe (57), and the second liquid pipe (60) is subjected to the first liquid side shut-off valve (72) and the second It diverts towards the liquid side shutoff valve (74). At that time, the liquid refrigerant passes through the subcooling heat exchanger (76).

The high pressure liquid refrigerant flows into the high pressure side flow passage (76a) of the subcooling heat exchanger (76). On the other hand, after passing through the high pressure side channel (76a) to the low pressure side channel (76b) of the subcooling heat exchanger (76), the second liquid pipe (60) branches to the main pipe (77) to pass through the expansion valve (78). The refrigerant that has been depressurized in) flows in. The refrigerant flowing in the low pressure side flow passage (76b) exchanges heat with the high pressure liquid refrigerant flowing in the high pressure side flow passage (76a) and evaporates, while the high pressure liquid refrigerant in the high pressure side flow passage (76a) is evaporated on the low pressure side The heat is released to the refrigerant of the flow path (76 b) to be a supercooled state. The refrigerant that has passed through the second liquid side shut-off valve (74) flows into the second liquid side communication pipe (54). The refrigerant that has passed through the first liquid side shut-off valve (72) flows into the first liquid side communication pipe (52). The evaporated refrigerant in the low pressure side channel (76b) flows into the injection pipe (81).

The liquid refrigerant flowing into the second liquid side communication pipe (54) flows into the refrigeration circuit (31) of the refrigeration unit (30). The liquid refrigerant that has flowed into the refrigeration circuit (31) is depressurized by the refrigeration expansion valve (33) and then flows into the refrigeration heat exchanger (32). In the refrigeration heat exchanger (32), the refrigerant absorbs heat from the air in the storage and evaporates. As a result, the internal air is cooled.

The refrigerant evaporated in the refrigeration heat exchanger (32) flows from the refrigeration circuit (31) into the second gas side communication pipe (53). After passing through the second gas side shut-off valve (73), the refrigerant flows into the first inflow branch pipe (55a) of the suction pipe (55) through the third four-way selector valve (19).

On the other hand, the liquid refrigerant that has flowed into the first liquid side communication pipe (52) is reduced in pressure by the indoor expansion valve (23), and then flows into the indoor heat exchanger (22). In the indoor heat exchanger (22), the refrigerant absorbs heat from room air and evaporates. As a result, the room air is cooled. The refrigerant evaporated in the indoor heat exchanger (22) passes through the first gas side connection pipe (51), the first four-way selector valve (17), and the second four-way selector valve (18) and 55) flows into the second inflow branch pipe (55b).

The refrigerant flowing into each of the first inflow branch pipe (55a) and the second inflow branch pipe (55b) of the suction pipe (55) as described above merges, and then the first outflow branch pipe (55c), the first inflow branch pipe 2) Divide into the outflow branch pipe (55d) and the third outflow branch pipe (55e) respectively. Then, the refrigerant flowing into the first to third outflow branch pipes (55c, 55d, 55e) is sucked into the corresponding first to third compressors (13a, 13b, 13c) and compressed (three units). If all the compressors are in operation).

On the other hand, the refrigerant flowing into the injection pipe (81) is branched to the first to third branch pipes (81a, 81b, 81c), and then the middle of the corresponding first to third compressors (13a, 13b, 13c) The pressure is introduced into the compression chamber. As a result, the discharge gas temperature of the first to third compressors (13a, 13b, 13c) decreases. In addition, the lubricating oil separated from the refrigerant discharged from the first to third compressors (13a, 13b, 13c) in the oil separator (16) is returned to the injection pipe (81) through the oil return pipe (50) Be done.

<First heating / cooling operation>
The first heating and cooling operation shown in FIG. 3 is an operation for heating the indoor unit (20) and cooling the refrigeration unit (30) without using the outdoor heat exchanger (12). In the first cooling / cooling operation, the cooling capacity (heat of evaporation) of the cold storage unit (30) and the heating capacity (heat of condensation) of the indoor unit (20) are balanced, and 100% heat recovery is performed.

The controller (100) switches the first four-way selector valve (17) and the third four-way selector valve (19) to the first state and switches the second four-way selector valve (18) to the second state to perform outdoor expansion. The valve (14) is controlled to the fully closed state, the refrigeration expansion valve (33) is controlled to the predetermined opening degree, and the opening degree of the indoor expansion valve (23) is controlled to the fully opened state. Further, the opening degree of the pressure control valve (67) is controlled to be fully open, and the on-off valve (64) is controlled to be fully closed.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) merges in the discharge pipe (56) and then the lubricating oil is separated in the oil separator (16), and the first four-way selector valve (17) and the first gas side communication pipe (51) to flow into the indoor heat exchanger (22). In the indoor heat exchanger (22), the refrigerant releases heat to room air and condenses. The liquid refrigerant condensed in the indoor heat exchanger (22) flows through the first liquid side communication pipe (52).

The liquid refrigerant flowing through the first liquid side communication pipe (52) flows into the outdoor unit (10), and flows into the receiver (15) through the fourth liquid pipe (79). The refrigerant of the receiver (15) passes through the antifreeze pipe (57), flows through the second liquid pipe (60), and further flows through the subcooling heat exchanger (76) into the second liquid side communication pipe (54) Do.

The liquid refrigerant flowing into the second liquid side communication pipe (54) flows into the refrigeration circuit (31) of the refrigeration unit (30). The liquid refrigerant that has flowed into the refrigeration circuit (31) is depressurized by the refrigeration expansion valve (33) and then flows into the refrigeration heat exchanger (32). In the refrigeration heat exchanger (32), the refrigerant absorbs heat from the air in the storage and evaporates. As a result, the internal air is cooled.

The refrigerant evaporated in the refrigeration heat exchanger (32) flows from the refrigeration circuit (31) into the second gas side communication pipe (53). After passing through the second gas side shut-off valve (73), the refrigerant flows into the first inflow branch pipe (55a) of the suction pipe (55) through the third four-way selector valve (19).

The refrigerant flowing into the first inflow branch pipe (55a) of the suction pipe (55) as described above is the first outflow branch pipe (55c), the second outflow branch pipe (55d), and the third outflow branch pipe (55e). I divide into each). Then, the refrigerant that has flowed into the first to third outflow branch pipes (55c, 55d, 55e) is drawn into the corresponding first to third compressors (13a, 13b, 13c) and compressed.

The injection of the intermediate pressure refrigerant into the first to third compressors (13a, 13b, 13c) by the injection piping (81) in the first heating / cooling operation is basically performed similarly to the cooling / cooling operation.

<Second heating / cooling operation>
In the second heating / cooling operation shown in FIG. 4, when the heating capacity of the indoor unit (20) remains in the first heating / cooling operation, the outdoor heat exchanger (12) is used as a radiator (condenser) to perform indoor operation. It is operation which performs heating of a unit (20), and cooling of a refrigeration unit (30). That is, in the second heating and cooling operation, the cooling capacity (heat of vaporization) of the refrigeration unit (30) and the heating capacity (heat of condensation) of the indoor unit (20) are not balanced, and excess condensation heat is Release to the outside in 12).

The controller (100) switches the first four-way switching valve (17), the second four-way switching valve (18) and the third four-way switching valve (19) to the first state. Further, the outdoor expansion valve (14), the indoor expansion valve (23), and the cold storage expansion valve (33) are controlled to a predetermined opening degree. Also, the pressure control valve (67) is controlled to be fully open, and the on-off valve (64) is controlled to be fully closed in principle.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) is split into two after the lubricating oil is separated in the oil separator (16) after joining in the discharge piping (56) Do. One of the branched refrigerant flows into the outdoor heat exchanger (12) through the second four-way selector valve (18), the first four-way selector valve (17) and the outdoor gas pipe (58), and the other is the first one. It flows into the indoor heat exchanger (22) through the four-way switching valve (17) and the first gas side connection pipe (51).

In the outdoor heat exchanger (12), the refrigerant releases heat to the outdoor air and condenses. The liquid refrigerant condensed by the outdoor heat exchanger (12) flows into the receiver (15). In the indoor heat exchanger (22), the refrigerant releases heat to room air and condenses. The liquid refrigerant condensed in the indoor heat exchanger (22) flows through the first liquid side communication pipe (52).

The liquid refrigerant flowing through the first liquid side communication pipe (52) flows into the outdoor unit (10), and flows into the receiver (15) through the fourth liquid pipe (79). The refrigerant joined at the receiver (15) passes through the antifreeze pipe (57), flows through the second liquid pipe (60), and further passes through the subcooling heat exchanger (76) to carry out the second liquid side communication pipe (54) Flow into

The liquid refrigerant flowing into the second liquid side communication pipe (54) flows into the refrigeration circuit (31) of the refrigeration unit (30). The liquid refrigerant that has flowed into the refrigeration circuit (31) is depressurized by the refrigeration expansion valve (33) and then flows into the refrigeration heat exchanger (32). In the refrigeration heat exchanger (32), the refrigerant absorbs heat from the air in the storage and evaporates. As a result, the internal air is cooled.

The refrigerant evaporated in the refrigeration heat exchanger (32) flows from the refrigeration circuit (31) into the second gas side communication pipe (53). After passing through the second gas side shut-off valve (73), the refrigerant flows into the first inflow branch pipe (55a) of the suction pipe (55) through the third four-way selector valve (19).

The refrigerant that has flowed into the first inflow branch pipe (55a) of the suction pipe (55) as described above includes the first outflow branch pipe (55c), the second outflow branch pipe (55d), and the third outflow branch pipe ( Each is diverted to 55e). Then, the refrigerant that has flowed into the first to third outflow branch pipes (55c, 55d, 55e) is drawn into the corresponding first to third compressors (13a, 13b, 13c) and compressed.

The injection of the intermediate pressure refrigerant into the first to third compressors (13a, 13b, 13c) by the injection piping (81) in the second heating / cooling operation is basically performed similarly to the cooling / cooling operation.

<Third heating and cooling operation>
In the third heating / cooling operation shown in FIG. 5, when the heating capacity of the indoor unit (20) runs short during the first heating / cooling operation, the outdoor unit (20) is used as an evaporator and the indoor unit (20) is used. Operation of cooling the refrigeration unit (30). That is, in the third heating and cooling operation, the cooling capacity (heat of evaporation) of the refrigeration unit (30) and the heating capacity (heat of condensation) of the indoor unit (20) are not balanced, and the evaporation heat that runs short is an outdoor heat exchanger Absorb in (12).

The controller (100) switches the first four-way switching valve (17) and the third four-way switching valve (19) to the first state, switches the second four-way switching valve (18) to the second state, and performs outdoor expansion Adjust the opening of the valve (14) appropriately. Further, the refrigeration expansion valve (33) is controlled to a predetermined opening degree, and the opening degree of the indoor expansion valve (23) is controlled to a fully open state. In addition, the opening degree of the on-off valve (64) and the pressure control valve (67) is controlled to the fully closed state.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) is joined in the discharge pipe (56) and then the lubricating oil is separated in the oil separator (16). It flows into the indoor heat exchanger (22) through the switching valve (17) and the first gas side connection pipe (51). In the indoor heat exchanger (22), the refrigerant releases heat to room air and condenses. The liquid refrigerant condensed in the indoor heat exchanger (22) flows through the first liquid side communication pipe (52).

The liquid refrigerant flowing through the first liquid side communication pipe (52) flows into the outdoor unit (10), and flows into the receiver (15) through the fourth liquid pipe (79). The liquid refrigerant that has flowed into the receiver (15) flows out of the receiver (15), flows through the second liquid pipe (60), passes through the subcooling heat exchanger (76), and then the second liquid side communication pipe (54) And divert to the bypass pipe (61).

The liquid refrigerant flowing into the second liquid side communication pipe (54) flows into the refrigeration circuit (31) of the refrigeration unit (30). The liquid refrigerant that has flowed into the refrigeration circuit (31) is depressurized by the refrigeration expansion valve (33) and then flows into the refrigeration heat exchanger (32). In the refrigeration heat exchanger (32), the refrigerant absorbs heat from the air in the storage and evaporates. As a result, the internal air is cooled.

The refrigerant evaporated in the refrigeration heat exchanger (32) flows from the refrigeration circuit (31) into the second gas side communication pipe (53). After passing through the second gas side shut-off valve (73), the refrigerant flows into the first inflow branch pipe (55a) of the suction pipe (55) through the third four-way selector valve (19).

The refrigerant flowing into the first inflow branch pipe (55a) of the suction pipe (55) as described above is branched into the first outflow branch pipe (55c) and the second outflow branch pipe (55d). Then, the refrigerant flowing into the first and second outflow branch pipes (55c, 55d) is sucked into the corresponding first and second compressors (13a, 13b) and compressed.

On the other hand, the liquid refrigerant that has flowed out of the receiver (15) and the subcooling heat exchanger (76) and then flows into the bypass pipe (61) is decompressed by the outdoor expansion valve (14), and then the outdoor heat exchanger (12 Flows into the In the outdoor heat exchanger (12), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (12) is passed through the outdoor gas pipe (58), the first four-way selector valve (17) and the second four-way selector valve (18), and the second refrigerant in the suction piping (55). It flows into the inflow branch pipe (55b). The refrigerant flowing into the second inflow branch pipe (55b) passes through the third outflow branch pipe (55e), is sucked into the third compressor (13c), and is compressed.

<Defrost operation>
In the cooling operation and the heating operation described above, the defrost operation is performed to melt the frost adhering to the cold storage heat exchanger (32).

<Defrost operation at the time of cooling>
In the defrosting operation at the time of cooling shown in FIG. 6, the room is cooled and, at the same time, the frost adhering to the refrigerator heat exchanger (32) of the refrigerator (30a) is removed. The controller (100) switches the first four-way selector valve (17), the second four-way selector valve (18) and the third four-way selector valve (19) to the second state, and fully opens the outdoor expansion valve (14). It controls to a state, adjusts the opening degree of a room expansion valve (23) suitably, and makes the opening degree of a refrigeration expansion valve (33) fully closed. The controller (100) controls the on-off valve (64) to be fully closed and controls the pressure regulating valve (67) to be fully open.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) merges in the discharge pipe (56) and then the lubricating oil is separated in the oil separator (16), and the first outflow branch pipe ( It branches into 56d) and the 3rd outflow branch pipe (56f).

The refrigerant flowing through the first outflow branch pipe (56d) passes through the first four-way selector valve (17) and the outdoor gas pipe (58) to flow into the outdoor heat exchanger (12). In the outdoor heat exchanger (12), the refrigerant releases heat to the outdoor air and condenses. The liquid refrigerant condensed in the outdoor heat exchanger (12) flows into the receiver (15) through the first liquid pipe (59) and is stored in the receiver (15).

The refrigerant that has flowed into the third outflow branch pipe (56f) of the discharge pipe (56) flows into the cold storage heat exchanger (32) through the second gas side connection pipe (53), and the cold storage heat exchanger (32) Apply heat to the frost that has adhered to it to melt the frost. The refrigerant flowing out of the refrigeration heat exchanger (32) flows through the second liquid side communication pipe (54), flows into the outdoor unit (10), flows through the refrigerant return pipe (80), and flows into the receiver (15). And merge with the refrigerant flowing from the outdoor heat exchanger (12) to the receiver (15).

The liquid refrigerant stored in the receiver (15) flows out of the receiver (15), passes through the antifreeze pipe (57), and passes through the third liquid pipe (62) to the first liquid side communication pipe (52). To flow.

The refrigerant flowing into the first liquid side communication pipe (52) is depressurized by the indoor expansion valve (23) and then flows into the indoor heat exchanger (22). In the indoor heat exchanger (22), the refrigerant absorbs heat from room air and evaporates. As a result, the room air is cooled. The refrigerant evaporated in the indoor heat exchanger (22) passes through the first gas side connection pipe (51), the first four way selector valve (17) and the second four way selector valve (18), and is drawn to the suction piping (55). Flows into the second inflow branch pipe (55b).

The refrigerant flowing into the second inflow branch pipe (55b) of the suction pipe (55) as described above is the first outflow branch pipe (55c), the second outflow branch pipe (55d), and the third outflow branch pipe (55e). I divide into each). Then, the refrigerant that has flowed into the first to third outflow branch pipes (55c, 55d, 55e) is drawn into the corresponding first to third compressors (13a, 13b, 13c) and compressed.

<Defrost operation at heating>
In the defrosting operation at the time of heating shown in FIG. 7, simultaneously with heating the room, the frost adhering to the chilled heat exchanger (32) of the refrigerator (30a) is removed. The controller (100) switches the first four-way switching valve (17) to the first state, switches the second four-way switching valve (18) and the third four-way switching valve (19) to the second state, and performs outdoor expansion. The opening degree of the valve (14) is appropriately adjusted, and the opening degree of the indoor expansion valve (23) and the cold storage expansion valve (33) is fully opened. Further, the controller (100) controls the cold on-off valve (64) to be fully closed and controls the pressure regulating valve (67) to be fully open.

In the refrigerant circuit (2), the refrigerant circulates as follows.

The refrigerant compressed by the first to third compressors (13a, 13b, 13c) merges in the discharge pipe (56) and then the lubricating oil is separated in the oil separator (16), and the first outflow branch pipe ( It branches into 56d) and the 3rd outflow branch pipe (56f).

The refrigerant flowing through the first outflow branch pipe (56d) flows into the indoor heat exchanger (22) through the first four-way selector valve (17) and the first gas side connection pipe (51). In the indoor heat exchanger (22), the refrigerant releases heat to room air and condenses. The liquid refrigerant condensed in the indoor heat exchanger (22) flows through the first liquid side communication pipe (52). The liquid refrigerant flowing through the first liquid side communication pipe (52) flows into the outdoor unit (10), and flows into the receiver (15) through the fourth liquid pipe (79).

The refrigerant that has flowed into the third outflow branch pipe (56f) of the discharge pipe (56) flows into the cold storage heat exchanger (32) through the second gas side connection pipe (53), and the cold storage heat exchanger (32) Apply heat to the frost that has adhered to it to melt the frost. The refrigerant flowing out of the refrigeration heat exchanger (32) flows through the second liquid side communication pipe (54), flows into the outdoor unit (10), flows through the refrigerant return pipe (80), and flows into the receiver (15). And merge with the refrigerant flowing from the indoor heat exchanger (22) to the receiver (15).

The liquid refrigerant flowing into the receiver (15) flows out of the receiver (15), flows through the second liquid pipe (60), passes through the subcooling heat exchanger (76), and then flows into the bypass pipe (61). The refrigerant flowing out of the subcooling heat exchanger (76) and flowing into the bypass pipe (61) is depressurized by the outdoor expansion valve (14), and then flows into the outdoor heat exchanger (12). In the outdoor heat exchanger (12), the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (12) is passed through the outdoor gas pipe (58), the first four-way selector valve (17) and the second four-way selector valve (18), and the second refrigerant in the suction piping (55). It flows into the inflow branch pipe (55b).

The refrigerant flowing into the second inflow branch pipe (55b) of the suction pipe (55) as described above is the first outflow branch pipe (55c), the second outflow branch pipe (55d), and the third outflow branch pipe (55e). I divide into each). Then, the refrigerant that has flowed into the first to third outflow branch pipes (55c, 55d, 55e) is drawn into the corresponding first to third compressors (13a, 13b, 13c) and compressed.

<Control of injection piping valve>
In the above-described injection pipe (81), an expansion valve (78) is connected to the main pipe (77), and flow control valves (82a, 82b, 82c) are connected to the respective branch pipes (81a, 81b, 81c). Ru. Therefore, when performing the injection operation of introducing the refrigerant from the injection pipe (81) to the compressors (13a, 13b, 13c), if the opening degree of all these valves is finely adjusted, the valve control becomes complicated. In addition, there is a possibility that the temperature (also referred to as discharge temperature) of the refrigerant discharged from each of the compressors (13a, 13b, 13c) may hunting due to such valve control, and the discharge temperature may not converge to the target value. So, in this embodiment, simplification of valve control is achieved by performing control of an expansion valve (refer to Drawing 9) mentioned below, and control of an expansion valve (78) (refer to Drawing 10).

<Details of control of each flow control valve>
In the control of each flow control valve (82a, 82b, 82c) shown in FIG. 9, in step ST11, whether the compressor (13a, 13b, 13c) corresponding to each flow control valve (82a, 82b, 82c) is in operation It judges whether or not. Then, when the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) is stopped, the process proceeds to step ST12, and all the flow rate control valves (82a, 82b, 82c) It will be closed. For example, in the control of the first expansion valve (82a), when the first compressor (13a) is stopped, the first expansion valve (82a) is fully closed. On the other hand, when the first compressor (13a) is in operation, the first expansion valve (82a) is in the open state, and the control of step ST13 to step ST19 is performed.

Next, at step ST13, the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) corresponding to the flow rate adjustment valve (82a, 82b, 82c) is the refrigerant discharged from the compressor (13a, 13b, 13c) during operation. It is determined whether or not it is the highest among the above. When this condition is satisfied, the flow rate control valves (82a, 82b, 82c) are maintained in the fully open state. For example, when all the compressors (13a, 13b, 13c) are in operation, the temperature (Td1) of the refrigerant discharged from the first compressor (13a) is the refrigerant discharged from all the compressors (13a, 13b, 13c) The highest temperature among the temperatures (Td1, Td2, Td3) of In this case, the process proceeds to step ST14, and the first expansion valve (82a) is maintained in the fully open state. In addition, when it transfers to step ST14, it is preferable to make the target flow control valve (82a, 82b, 82c) full open thru | or the largest opening degree. However, the flow rate control valves (82a, 82b, 82c) may be maintained at a predetermined fixed opening degree, and may not necessarily be the full opening or the maximum opening degree.

By performing the control of step ST13, any one of the flow rate control valves (82a, 82b, 82c) is fully opened. However, the opening degree of the expansion valve (78) of the main pipe (77) is adjusted based on the discharge temperature of the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c). Thus, even when the flow control valves (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest discharge temperature are fully opened, the compressors (13a, 13b, 13c) are supplied. The amount of refrigerant can be adjusted (details will be described later).

In step ST13, when the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) corresponding to the flow rate adjustment valve (82a, 82b, 82c) is not the highest, the process proceeds to step ST15. In step S15, it is determined whether the superheating condition (whether the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) is excessively high) is determined. If it is determined in step ST15 that the overheat state has occurred, the process proceeds to step ST16, and the opening degree of the flow rate control valve (82a, 82b, 82c) becomes large. As a result, the amount of refrigerant supplied to the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) is increased, and the overheat state can be eliminated.

Here, as the superheating condition in step ST15, condition 1) For example, the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) is a predetermined value (for example, 100.degree. C.) Condition 2 higher than that, the refrigerant temperature of the discharge of the compressor (13a, 13b, 13c) corresponding to the flow rate adjustment valve (82a, 82b, 82c) is higher than a predetermined value (for example, 80.degree. C.). , Etc. are used. If one or both of the condition 1 and the condition 2 are satisfied, the process proceeds to step ST16.

In step ST17, it is determined whether the wet condition (whether the refrigerant in the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) is liquid rich). In step ST17, when it is determined that the state is wet, the process proceeds to step ST18, and the opening degree of the flow rate adjustment valve (82a, 82b, 82c) becomes smaller. As a result, the amount of refrigerant supplied to the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) decreases, and the wet state can be eliminated.

Here, as the wet condition in step ST17, condition 3) For example, the discharge refrigerant temperature of the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) is higher than a predetermined value (for example, 50 ° C) Condition 4) the degree of superheat of the refrigerant discharged from the compressor (13a, 13b, 13c) corresponding to the flow control valve (82a, 82b, 82c) is smaller than a predetermined value (for example, 5 ° C) . If one or both of the condition 3 and the condition 4 are satisfied, the process proceeds to step ST18.

If the compressors (13a, 13b, 13c) are neither overheated nor wet, the process proceeds to step ST19. In step ST19, the flow rate control valve (82a) is set such that the temperature of the refrigerant discharged from the compressor (13a, 13b, 13c) corresponding to the flow rate control valve (82a, 82b, 82c) approaches a target value (for example, 90.degree. C.). , 82b, 82c) are controlled.

As described above, in the control of each flow control valve (82a, 82b, 82c), the flow control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest discharge temperature is fully opened. It becomes. At the same time, as the discharge temperature of the compressor (13a, 13b, 13c) corresponding to the other flow rate control valves (82a, 82b, 82c) approaches the target temperature, the other flow rate control valves (82a, 82b, 82c) Is adjusted.

<Details of expansion valve control>
On the other hand, the opening degree of the expansion valve (78) is adjusted for the compressor (13a, 13b, 13c) having the highest discharge temperature. Specifically, first, in step ST21 of FIG. 10, it is determined whether the compressor (13a, 13b, 13c) with the highest discharge temperature is the wet condition. As described above, since the flow rate control valves (82a, 82b, 82c) corresponding to the compressors (13a, 13b, 13c) with the highest discharge temperature are fully opened, the excess refrigerant is discharged from the compressors (13a, 13b). , 13c).

In step ST21, when the wet condition is satisfied, the process proceeds to step ST22, and the opening degree of the expansion valve (78) decreases to a predetermined opening degree (for example, 50% to 80% of the current opening degree). Thereby, the wet state of the compressor (13a, 13b, 13c) can be quickly eliminated. Here, the wet condition in step ST21 is the same as that in step ST17 described above.

In step ST22, it is determined whether the compressor (13a, 13b, 13c) having the highest discharge temperature is in the superheating condition. When the overheat condition is satisfied, the process proceeds to step ST24, and the opening degree of the expansion valve (78) is increased by a predetermined opening degree (for example, 10 to 30 pulses). Thereby, the overheat state of this compressor (13a, 13b, 13c) can be eliminated promptly. Here, the heating condition in step ST22 is the same as that in step ST23 described above.

If the compressor (13a, 13b, 13c) with the highest discharge temperature is neither overheated nor wet, the process proceeds to step ST25. In step ST25, the degree of opening of the expansion valve (78) such that the temperature (maximum discharge refrigerant temperature (Tdmax)) of the refrigerant discharged from the compressor (13a, 13b, 13c) approaches a target value (for example, 95 ° C.) Is controlled.

As described above, the flow control valves (82a, 82b, 82c) corresponding to the compressors (13a, 13b, 13c) having the highest discharge temperature are fully opened. However, the opening degree of the expansion valve (78) is controlled so that the discharge temperature of the compressor (13a, 13b, 13c) approaches the target value. Further, the opening degree of the remaining flow rate control valves (82a, 82b, 82c) is controlled so that the discharge temperature of the remaining compressors (13a, 13b, 13c) approaches the target value. As a result, in the injection operation, the number of valves to be controlled can be substantially reduced by one, and valve control can be simplified.

By the way, in the control of such an expansion valve (78), the pressure of the injection pipe (81) becomes higher than the maximum value (Pm) of the pressure of the intermediate port of the operating compressor (13a, 13b, 13c) Thus, it is preferable to set the lower limit value of the opening degree of the expansion valve (78). Here, the pressure of the injection pipe (81) is the detection value (injection pressure (PI)) of the pressure sensor (117), and the maximum pressure of the intermediate port of the operating compressor (13a, 13b, 13c) The value (Pm) is, for example, a value obtained by multiplying the detection value (first suction pressure (Ps1)) of the first suction pressure sensor (114a) by a predetermined coefficient (1.3), for example, the second suction pressure sensor (114b) The higher one of the values obtained by multiplying the predetermined detected value (second suction pressure (Ps2)) by the predetermined coefficient (1.3) can be used.

When the degree of opening of the expansion valve (78) becomes excessively small and the injection pressure (PI) becomes lower than the maximum value (Pm) of the pressure at the intermediate port, each compressor (13a, 13b, 13c) from the injection pipe (81) ) Can not be reliably introduced, and the refrigerant may flow back. On the other hand, in the present embodiment, the lower limit value of the opening degree of the expansion valve (78) is set such that the injection pressure (PI) becomes higher than the maximum value (Pm) of the pressure of the intermediate port. Therefore, the above-described injection operation can be continued while preventing such backflow of the refrigerant.

In the example described above, when there are a plurality of compressors in which the temperature of the discharged refrigerant is the highest among all the compressors (13a, 13b, 13c), the flow rate control valves (82a, 82b, Let 82c) be a fixed opening. Specifically, for example, when the temperature (Td1) of the discharge refrigerant of the first compressor (13a) and the temperature (Td2) of the discharge refrigerant of the second compressor (13b) are maximum, the first flow control valve (82a) and the second flow control valve (82b) are fixedly opened, and the openings of the third flow control valve (82c) and the expansion valve (78) are adjusted.

Further, when the temperatures (Td1, Td2, Td3) of the refrigerant discharged from all the compressors (13a, 13b, 13c) are equal, all flow rate control valves (82a, 82b, 82c) have fixed opening degrees, and the expansion valves ( Adjust the opening of 78).

<Control of Expansion Valve Associated with Switching Operation>
In the above embodiment, for example, when switching from the second heating / cooling operation (FIG. 2) to the defrost operation (FIG. 7), refrigeration heat exchange which was an evaporator by switching operation of each four-way switching valve (17, 18, 19) The vessel (32) is changed to a condenser, and the outdoor heat exchanger (12), which was a condenser, becomes an evaporator. Immediately after this switching operation, the differential pressure of the refrigerant circuit (2) decreases, and the evaporation pressure and the evaporation temperature of the outdoor heat exchanger (12) increase. Therefore, the liquid refrigerant can not be evaporated sufficiently by the outdoor heat exchanger (12), and the degree of suction superheat of the refrigerant drawn into the compressor (13a, 13b, 13c) may be reduced. When the liquid refrigerant is introduced from the injection pipe (81) to the compressor (13a, 13b, 13c) despite the small degree of suction superheat of the drawn refrigerant, the refrigerant in the compressor (13a, 13b, 13c) becomes wet. It is easy to be in the state. In this case, the liquid refrigerant dissolves in the lubricating oil of the compressor (13a, 13b, 13c) and the lubricating oil is diluted. As a result, the viscosity of the lubricating oil is lowered, which causes a problem that lubrication failure of the sliding portion of the compressor (13a, 13b, 13c) occurs. Therefore, in the present embodiment, the expansion valve (78) is fully closed or slightly opened in conjunction with the switching operation of each four-way switching valve (17, 18, 19). Thereby, it is possible to prevent the liquid refrigerant from being introduced from the injection pipe (81) to each compressor (3a, 13b, 13c) at the time of switching operation, and the refrigerant inside each compressor (3a, 13b, 13c) Can be avoided from becoming wet.

-Effect of the embodiment-
In the above embodiment, the flow control valve (82a, 82b, 82c) corresponding to one of the plurality of compressors (13a, 13b, 13c) is maintained at the fixed opening degree. Therefore, it is not necessary to appropriately adjust the opening degree of the flow rate control valve (82a, 82b, 82c).

On the other hand, the opening degree of the expansion valve (78) and the remaining flow rate control valves (82a, 82b, 82c) so that each temperature of the refrigerant discharged from each compressor (13a, 13b, 13c) approaches a predetermined target temperature. Is adjusted. Thereby, the injection operation can be performed while reducing the substantial number of valves to be controlled.

In the injection operation, the opening degree of the flow rate control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant is maintained at the maximum opening degree. The compressor (13a, 13b, 13c) having the highest discharge temperature among the plurality of compressors (13a, 13b, 13c) needs to introduce a large amount of liquid refrigerant. Therefore, by maximizing the opening degree of the flow rate control valve (82a, 82b, 82c), the refrigerant can be promptly introduced into the compressor (13a, 13b, 13c).

<< Modification of Embodiment >>
In the above-described embodiment, a plurality of evaporators (22, 32) are connected to the refrigerant circuit (2), and the refrigerant evaporates at different temperatures in these evaporators (22, 32). A cycle is performed. However, the refrigerant circuit (2) may not necessarily perform the different temperature evaporation type refrigeration cycle, and may be configured to have only one evaporator (32).

In the refrigerant circuit (2) of the refrigeration system (1) of the modification shown in FIG. 11, a plurality of (for example, two) compressors (first compressor (13a) and second compressor (13b)), 1 Two radiators (for example, an outdoor heat exchanger (12)) and one evaporator (for example, a refrigeration heat exchanger (32)) are connected. The first compressor (13a) and the second compressor (13b) are individually configured to have variable capacities. That is, the rotational speeds of the first compressor (13a) and the second compressor (13b) are configured to be variable by inverter control.

The subcooling heat exchanger (76) is connected to the liquid pipe (90) of the refrigerant circuit (2). The inflow pipe of the injection pipe (81) is connected to the liquid pipe (90). A liquid pipe (90) is connected to the high pressure side flow passage (76a) of the subcooling heat exchanger (76). The low pressure side flow passage (76b) of the subcooling heat exchanger (76) constitutes a part of the main pipe (77) of the injection pipe (81). The first branch pipe (81a) of the injection pipe (81) is connected to the intermediate pressure port of the first compressor (13a), and the second branch pipe (79) of the injection pipe (81) is the second compressor (81). It is connected to the intermediate pressure port of 13 b).

An expansion valve (78) is connected to the upstream side of the low pressure side flow passage (76b) in the main pipe (77). A first flow control valve (82a) is connected to the first branch pipe (81a). The second flow control valve (82b) is connected to the second branch pipe (81b).

A first discharge temperature sensor (111a) is provided on the discharge side (first inflow branch pipe (56a)) of the first compressor (13a). A second discharge temperature sensor (111b) is provided on the discharge side (second inflow branch pipe (56b)) of the second compressor (13b). A discharge pressure sensor (112) is provided on the discharge side (discharge pipe (56)) of the first compressor (13a) and the second compressor (13b). The main pipe (77) is provided with a pressure sensor (117). Similar to the above embodiment, the degree of discharge superheat of the first compressor (13a) and the temperature of the discharge refrigerant of the second compressor, the degree of superheat of the discharge refrigerant, the pressure of the intermediate pressure port, etc. Is measurable.

During operation of the refrigeration system (1), the first compressor (13a) and the second compressor (13b) are driven, and the outdoor heat exchanger (12), for example, becomes a radiator (condenser), and a refrigeration heat exchanger ( A refrigeration cycle is performed in which 32) becomes an evaporator. During this operation, the injection operation is performed as in the above embodiment. That is, the first compressor (13a) and the second compressor (13b) are supplied with the refrigerant whose flow rate is adjusted by the flow rate control valves (82a, 82b). This is because the first compressor (13a) and the second compressor (13b) have different operating capacities or rotational speeds, so the amount of injection required for each of the compressors (13a, 13b) is different.

As in the above embodiment, in this modification as well, in the injection operation, of the first compressor (13a) and the second compressor (13b), it corresponds to the compressor (13a, 13b) with the highest temperature of the discharged refrigerant. The opening degree of the flow rate adjustment valve (82a, 82b) is maintained at the maximum opening degree. Then, the opening degrees of the expansion valve (78) and the remaining flow control valves (82a, 82b) are adjusted so that the temperatures of the refrigerant discharged from the compressors (13a, 13b) approach the predetermined target temperature. . Thereby, the injection operation can be performed while reducing the substantial number of valves to be controlled.

<< Other Embodiments >>
The refrigeration system (1) of the above embodiment has an indoor unit (10) and a refrigeration unit (30). However, the refrigeration system (1) may have a refrigeration unit that performs refrigeration inside the refrigerator. The refrigeration system (1) may have a hot water supply unit, and may be configured to heat water with a hot water supply heat exchanger (radiator or condenser) of the hot water supply unit.

The end of the injection pipe (81) of the above embodiment is connected to the intermediate pressure port (intermediate pressure compression chamber) of the compressor (13a, 13b, 13c). However, the end of the injection pipe (81) may be connected to the suction port of the compressor (13a, 13b, 13c) or to the suction pipe. That is, the injection pipe (81) may introduce the refrigerant in the liquid line to the suction side of the compressor (13a, 13b, 13c).

The number of compressors (13a, 13b, 13c) in the above embodiment is merely an example, and may be one, two, or four or more.

The refrigeration system (1) of the above embodiment is a so-called four-pipe system in which four connection pipes are provided, but it may be a so-called three-pipe system in which three connection pipes are provided.

The present invention is useful for refrigeration systems.

2 Refrigerant circuit 12 Outdoor heat exchanger (dissipator)
22 Indoor heat exchanger (evaporator)
32 Refrigerated Heat Exchanger (Evaporator)
60 fluid line 77 main pipe 78 flow control valve 81 injection piping (injection circuit)
81a first branch pipe 81b second branch pipe 81c third branch pipe 82a first flow control valve 82b second flow control valve 82c third flow control valve 100 controller (control section)

Claims (5)

1. It has a refrigerant circuit (2) in which a plurality of compressors (13a, 13b, 13c), at least one radiator (12), and at least one evaporator (22, 32) are connected, and a refrigeration cycle is performed. Refrigeration system, and
   In the refrigerant circuit (2), the refrigerant in the liquid line (60) between the radiator (12) and the evaporator (22, 32) is introduced into each compressor (13a, 13b, 13c) by injection The injection circuit (81) for operation is connected,
   The injection circuit (81)
   One main pipe (77) connected to the fluid line (60) and having an expansion valve (78);
   A plurality of branch pipes (81a, 81a, 82b, 82c) branched from the outflow end of the main pipe (77) and connected to the plurality of compressors (13a, 13b, 13c) 81b and 81c) are provided.
   In the injection operation, the flow control valve (82a, 82b, 82c) corresponding to the predetermined compressor (13a, 13b, 13c) among the plurality of compressors (13a, 13b, 13c) is set to a predetermined fixed opening degree. A refrigeration apparatus comprising: a control unit (100) for maintaining the expansion valve (78) and the remaining flow rate control valves (82a, 82b, 82c) respectively.
2. In claim 1,
   The control unit (100) maintains the flow control valves (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant at the predetermined fixed opening degree. A refrigeration system characterized by
3. In claim 2,
   The control unit (100) maintains the predetermined opening degree of the flow rate control valve (82a, 82b, 82c) corresponding to the compressor (13a, 13b, 13c) having the highest temperature of the discharged refrigerant at a maximum. A refrigeration system characterized by
4. In any one of claims 1 to 3,
   The refrigerant circuit (2) is characterized in that a refrigeration cycle is performed in which refrigerants evaporated at different evaporation pressures of a plurality of evaporators (22, 32) are respectively sucked into different compressors (13a, 13b, 13c) Refrigeration equipment.
5. In any one of claims 1 to 3,
   One evaporator (22) is connected to the said refrigerant circuit (2), The freezing apparatus characterized by the above-mentioned.

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