WO2021065111A1

WO2021065111A1 - Heat source unit and refrigeration device

Info

Publication number: WO2021065111A1
Application number: PCT/JP2020/025133
Authority: WO
Inventors: 秀一田口; 竹上　雅章; 明敏上野; 拓未大薗
Original assignee: ダイキン工業株式会社
Priority date: 2019-09-30
Filing date: 2020-06-26
Publication date: 2021-04-08
Also published as: JP6777215B1; JP2021055983A

Abstract

This heat source unit constitutes a refrigerant circuit (6) which is connected to use circuits (51, 61) respectively having a first use unit (60) and a second user unit (50) which have different vaporization temperatures and performs a refrigeration cycle, wherein a heat source circuit (11) of the heat source unit comprises: a main flow path (M) provided with a first depressurization mechanism (14); a first branch flow path (o8) that is connected to an end section of the main flow path (M) and communicates with the first use unit (60); a second branch flow path (o6) that is connected to the end section of the main flow path (M) and communicates with the second use unit (50); and a second depressurization mechanism (18) provided to the first flow path (o8).

Description

Heat source unit and refrigeration equipment

This disclosure relates to a heat source unit and a refrigerating device.

Conventionally, a refrigerating device having a compression element for compressing a refrigerant and performing a refrigerating cycle has been known. This refrigerating device is widely used as an air conditioner for heating and cooling a room and a cooler for a refrigerator or the like for storing food or the like. In this type of refrigerating device, the outdoor unit installed outdoors includes a plurality of utilization units having different evaporation temperatures (for example, a refrigerating unit such as a showcase for refrigeration / freezing, and an air conditioning unit such as an indoor unit for air conditioning). ), Are connected in parallel. This refrigerating device is installed in, for example, a convenience store or the like, and it is possible to air-condition the inside of the store and cool the showcase or the like by installing only one refrigerating device (see Patent Document 1).

Japanese Unexamined Patent Publication No. 2019-66158

As described above, the refrigerating apparatus having a plurality of utilization units having different evaporation temperatures is provided with an injection circuit for introducing a refrigerant into a portion that becomes an intermediate pressure between the discharge pressure and the suction pressure of the compression element, and the refrigeration cycle is performed. There is a refrigeration system to do. In such a refrigerating apparatus, in the refrigerant circuit in the outdoor unit, a part of the refrigerant decompressed by the outdoor expansion valve may be used by flowing into the injection circuit. In this case, the efficiency of the refrigerating apparatus is improved by introducing a refrigerant having a pressure intermediate between the discharge pressure and the suction pressure. However, when the pressure of the refrigerant is lowered to the intermediate pressure in the outdoor unit, the difference pressure between the evaporation pressure and the intermediate pressure of the utilization unit having the higher evaporation temperature becomes smaller. As a result, the refrigerant of the outdoor unit becomes difficult to flow to the utilization unit having a higher evaporation temperature, and there arises a problem that the cooling capacity of the utilization unit cannot be secured.

An object of the present disclosure is to secure the capacity of the utilization unit having the higher evaporation temperature in the refrigeration apparatus including a plurality of utilization units having different evaporation temperatures.

The first aspect is a utilization circuit of a utilization unit (50, 60) having a first utilization unit (60) and a second utilization unit (50) having a higher refrigerant evaporation temperature than the first utilization unit (60). It is a heat source unit including a heat source circuit (11) connected to (51, 61) to form a refrigerant circuit (6) that performs a refrigeration cycle, and a control unit (100) that controls the heat source circuit (11).

The heat source circuit (11) is the compression element having a first compression unit (22, 23) and a second compression unit (21) that further compresses the refrigerant compressed by the first compression unit (22, 23). (C), a radiator (13), a first decompression mechanism (14), and a main flow path (M) connected to the downstream side of the radiator (13) and provided with the first decompression mechanism (14). , The first branch flow path (o8) connected to the end of the main flow path (M) and communicating with the first utilization unit (60), and the end of the main flow path (M). The second branch flow path (o6) communicating with the second utilization unit (50), one end is connected to the main flow path (M), and the other end is the first compression section (22, 23) and the second compression. An intermediate injection circuit (49) connected between the parts (21) and into which the refrigerant decompressed by the first decompression mechanism (14) flows in, and a second decompression mechanism provided in the first branch flow path (o8). (18) and.

In the first aspect, the refrigerant of the heat source unit easily flows to the second utilization unit (50), and the cooling capacity of the second utilization unit (50) can be secured.

In the second aspect, in the first aspect, the heat source circuit (11) includes a gas-liquid separator (15), and the intermediate injection circuit (49) is connected to the gas-liquid separator (15). The first refrigerant pipe (37) is provided, and in the first refrigerant pipe (37), the gas refrigerant in the gas-liquid separator (15) is transferred from the gas-liquid separator (15) to the first compression unit ( It is configured to flow into the flow path between 22 and 23) and the second compression unit (21).

In the second aspect, the gas refrigerant stored in the gas-liquid separator (15) is placed between the first compression unit (22, 23) and the second compression unit (21) via the intermediate injection circuit (49). Can be introduced in.

In the third aspect, in the first or second aspect, the heat source circuit (11) has a pressure acquisition unit (48) that detects or estimates the pressure of the refrigerant after decompression by the second decompression mechanism (18). The second decompression mechanism (18) is a valve whose opening degree can be adjusted, and the control unit (100) uses the pressure detected or estimated by the pressure acquisition unit (48) as the target pressure. In addition, the opening degree of the second decompression mechanism (18) is controlled.

In the third aspect, the pressure of the refrigerant supplied to the first utilization unit (60) can be adjusted to the target pressure.

A fourth aspect is that in any one of the first to third aspects, the heat source circuit (11) is placed between the first decompression mechanism (14) and the second decompression mechanism (18). A cooling heat exchanger (16) to be connected is provided, and the cooling heat exchanger (16) includes a first flow path (16a) connected to a liquid pipe through which the liquid refrigerant of the heat source circuit (11) flows, and the above. It has a second flow path (16b) through which the refrigerant is diverted from the liquid pipe and the reduced pressure flows, and the refrigerant in the first flow path (16a) is cooled by the refrigerant in the second flow path (16b). The second flow path (16b) constitutes the intermediate injection circuit (49).

In the fourth aspect, the refrigerant in the second flow path (16b) of the cooling heat exchanger (16) absorbs heat from the refrigerant in the first flow path (16a) and evaporates, and flows through the intermediate injection circuit (49). .. As a result, the refrigerant in the second flow path (16b) can be introduced into the flow path between the first compression section (22, 23) and the second compression section (21).

In a fifth aspect, in the fourth aspect, the control unit (100) has a cooling capacity of the cooling heat exchanger (16) so that the refrigerant flowing out of the second decompression mechanism (18) is in a liquid state. To control.

In the fifth aspect, the enthalpy difference of the refrigerant between the inlet and the outlet of the first utilization unit (60) can be increased.

In the sixth aspect, in any one of the first to fifth aspects, the first utilization unit (60) is a cooling unit for cooling the inside of the refrigerating equipment, and the second utilization unit (60). 50) is an air conditioning unit that air-conditions the room.

A seventh aspect is, in any one of the first to sixth aspects, the control unit (100) compresses the refrigerant with the compression element (C) to a pressure equal to or higher than the critical pressure, and the first decompression mechanism. The refrigerant circuit (6) is controlled so as to perform a refrigeration cycle in which the pressure is reduced to the subcritical pressure in (14).

In the seventh aspect, the refrigerant compressed to the critical pressure or higher can be depressurized to the subcritical pressure by the first depressurizing mechanism. As a result, the gas phase component of the refrigerant in the subcritical region can be introduced into the flow path between the first compression section (22, 23) and the second compression section (21).

In the eighth aspect, in any one of the first to seventh aspects, the refrigerant is carbon dioxide.

In the ninth aspect, in any one of the first to eighth aspects, the downstream portion of the second decompression mechanism (18) in the first branch flow path (o8) is used with the utilization unit (50, It is provided with a connection pipe (83) connected to a low-pressure gas pipe (20) through which a refrigerant flows from the compression element (C) to the compression element (C), and an auxiliary valve (19) provided in the connection pipe (83).

In the ninth aspect, the auxiliary valve (19) is provided in the connecting pipe (83) connecting the liquid pipe (o8) and the low pressure gas pipe (20). When the auxiliary valve (19) is open, the liquid-side communication pipe that connects the heat source unit (10) to the utilization unit (60) communicates with the low-pressure gas pipe (20) via the connection pipe (83). Therefore, when the second outdoor expansion valve (18) of the intermediate unit (80) is closed, an excessive increase in the internal pressure of the liquid side connecting pipe is suppressed, and as a result, the liquid side connecting pipe is damaged and used. It is possible to avoid damage to the unit (60).

A tenth aspect is, in any one of the first to ninth aspects, the heat source unit (10) is a main heat source unit (10a) and an auxiliary unit (10b) separated from the main heat source unit (10a). , 80), and the auxiliary unit (10b, 80) includes the second decompression mechanism (18).

In the tenth aspect, the auxiliary unit (10b, 80) provided with the second decompression mechanism (18) can be separated from the main heat source unit (10a). As a result, the auxiliary unit (10b, 80) can be connected to the existing main heat source unit (10a), and the effects of the first to eighth aspects can be realized.

In the eleventh aspect, the evaporation temperature of the refrigerant is higher than that of the heat source unit (10) of any one of the first to tenth aspects, the first utilization unit (60), and the first utilization unit (60). The heat source circuit (11) and the utilization unit (50) of the heat source unit (10) are provided with the utilization unit (50, 60) having the utilization circuit (51, 61) including the high second utilization unit (50). , 60) is connected to the utilization circuits (51, 61) to form a refrigerant circuit (6) that performs a refrigeration cycle.

FIG. 1 is a piping system diagram of the refrigerating apparatus according to the first embodiment. FIG. 2 is a flowchart showing the relationship between the controller, various sensors, and various devices. FIG. 3 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the cold operation. FIG. 4 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the cooling operation. FIG. 5 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the cooling / cooling operation. FIG. 6 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the heating operation. FIG. 7 is a view corresponding to FIG. 1 showing the flow of the refrigerant in the heating / cooling operation. FIG. 8 is a Ph diagram of a conventional refrigeration system. FIG. 9 is a diagram corresponding to FIG. 8 in which a part of the pressure is changed in the Ph diagram of the conventional refrigerating apparatus. FIG. 10 is a flowchart showing the control of the second decompression mechanism according to the first embodiment. FIG. 11 is a flowchart showing the activation control of the first compressor. FIG. 12 is a Ph diagram of the refrigerating apparatus according to the first embodiment. FIG. 13 is a piping system diagram of the refrigerating apparatus according to the modified example of the first embodiment. FIG. 14 is a flowchart showing the control of the second decompression mechanism according to the second embodiment. FIG. 15 is a piping system diagram of the refrigerating apparatus according to the third embodiment. FIG. 16 is a flow chart showing the control of the second outdoor expansion valve performed by the controller of the third embodiment. FIG. 17 is a graph showing the relationship between the opening degree of the auxiliary valve controlled by the controller of the third embodiment and the measured value of the outlet pressure sensor. FIG. 18 is a graph showing the relationship between the opening degree of the auxiliary valve controlled by the controller of the modified example of the third embodiment and the measured value of the outlet pressure sensor. FIG. 19 is a piping system diagram of the refrigerating apparatus according to the fourth embodiment. FIG. 20 is a block diagram showing the relationship between the constituent devices of the intermediate unit and the hydraulic pressure controller according to the fourth embodiment. FIG. 21 is a block diagram showing the relationship between the constituent devices of the intermediate unit and the hydraulic pressure controller in the first modification of the fourth embodiment.

Hereinafter, the embodiment will be described with reference to the drawings. It should be noted 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.

<< Embodiment 1 >>
<overall structure>
The refrigerating apparatus (1) according to the first embodiment simultaneously cools the object to be cooled and air-conditions the room. The cooling target here includes air in equipment such as refrigerators, freezers, and showcases. Hereinafter, such equipment will be referred to as cold equipment.

As shown in FIG. 1, the refrigerating device (1) includes a heat source unit (10) installed outdoors, a first utilization unit (60) (cooling unit) for cooling the air inside the refrigerator, and an indoor air conditioner. A second utilization unit (50) (air conditioning unit) and a controller (100) are provided. FIG. 1 illustrates one air conditioning unit (50). The refrigeration system (1) may have two or more air conditioning units (50) connected in parallel. FIG. 1 illustrates one cooling unit (60). The refrigeration system (1) may have two or more cooling units (60) connected in parallel. The refrigerant circuit (6) is configured by connecting these units (10,50,60) with four connecting pipes (2,3,4,5).

The four connecting pipes (2,3,4,5) are the first liquid connecting pipe (2), the first gas connecting pipe (3), the second liquid connecting pipe (4), and the second gas connecting pipe (2). It consists of 5). The first liquid connecting pipe (2) and the first gas connecting pipe (3) correspond to the air conditioning unit (50). The second liquid connecting pipe (4) and the second gas connecting pipe (5) correspond to the cooling unit (60).

In the refrigerant circuit (6), the refrigeration cycle is performed by circulating the refrigerant. The refrigerant of the refrigerant circuit (6) of this embodiment is carbon dioxide. The refrigerant circuit (6) is configured to perform a refrigeration cycle in which the refrigerant exceeds the critical pressure.

<Heat source unit>
The heat source unit (10) has an outdoor fan (12) and an outdoor circuit (11). In the outdoor circuit (11), the compression element (C), the flow path switching mechanism (30), the outdoor heat exchanger (13), the first outdoor expansion valve (14), and the gas-liquid separator (15) are connected in this order. It also has a cooling heat exchanger (16) and an intercooler (17).

<Compression element>
The compression element (C) compresses the refrigerant. The compression element (C) has a first compressor (21), a second compressor (22), and a third compressor (23). The compression element (C) is configured as a two-stage compression type in which the refrigerant compressed by the first compression unit (22, 23) is further compressed by the second compression unit (21). The first compression unit (22, 23) is a second compressor (22) and a third compressor (23) that constitute a low-stage compressor. The second compression unit (21) is a first compressor (21) that constitutes a high-stage compressor. The second compressor (22) and the third compressor (23) are connected in parallel with each other. The first compressor (21) and the second compressor (22) are connected in series. The first compressor (21) and the third compressor (23) are connected in series. The first compressor (21) constitutes the first compression unit, and the second compressor (22) and the third compressor (23) form the second compression unit. The first compressor (21), the second compressor (22), and the third compressor (23) are rotary compressors in which a compression mechanism is driven by a motor. The first compressor (21), the second compressor (22), and the third compressor (23) are configured in a variable capacitance type in which the operating frequency or the rotation speed can be adjusted.

The first suction pipe (21a) and the first discharge pipe (21b) are connected to the first compressor (21). A second suction pipe (22a) and a second discharge pipe (22b) are connected to the second compressor (22). A third suction pipe (23a) and a third discharge pipe (23b) are connected to the third compressor (23). The first suction pipe (21a) constitutes an intermediate pressure portion between the first compression portion (22, 23) and the second compression portion (21).

The second suction pipe (22a) communicates with the cooling unit (60). The second compressor (22) is a cold side compressor corresponding to the cold unit (60). The third suction pipe (23a) communicates with the air conditioning unit (50). The third compressor (23) is an indoor compressor corresponding to the air conditioning unit (50).

<Flow path switching mechanism>
The flow path switching mechanism (30) switches the flow path of the refrigerant. The flow path switching mechanism (30) includes the first pipe (31), the second pipe (32), the third pipe (33), the fourth pipe (34), the first three-way valve (TV1), and the second three-way valve. Has (TV2). The inflow end of the first pipe (31) and the inflow end of the second pipe (32) are connected to the first discharge pipe (21b). The first pipe (31) and the second pipe (32) are pipes on which the discharge pressure of the compression element (C) acts. The outflow end of the third pipe (33) and the outflow end of the fourth pipe (34) are connected to the third suction pipe (23a) of the third compressor (23). The third pipe (33) and the fourth pipe (34) are pipes on which the suction pressure of the compression element (C) acts.

The first three-way valve (TV1) has a first port (P1), a second port (P2), and a third port (P3). The first port (P1) of the first three-way valve (TV1) is connected to the outflow end of the first pipe (31) which is a high-pressure flow path. The second port (P2) of the first three-way valve (TV1) is connected to the inflow end of the third pipe (33), which is a low-pressure flow path. The third port (P3) of the first three-way valve (TV1) is connected to the indoor gas side flow path (35).

The second three-way valve (TV2) has a first port (P1), a second port (P2), and a third port (P3). The first port (P1) of the second three-way valve (TV2) is connected to the outflow end of the second pipe (32), which is a high-pressure flow path. The second port (P2) of the second three-way valve (TV2) is connected to the inflow end of the fourth pipe (34), which is a low-pressure flow path. The third port (P3) of the second three-way valve (TV2) is connected to the outdoor gas side flow path (36).

The first three-way valve (TV1) and the second three-way valve (TV2) are electric three-way valves. Each of the three-way valves (TV1 and TV2) switches between a first state (the state shown by the solid line in FIG. 1) and a second state (the state shown by the broken line in FIG. 1). In each of the three-way valves (TV1 and TV2) in the first state, the first port (P1) and the third port (P3) communicate with each other, and the second port (P2) is closed. In each of the three-way valves (TV1, TV2) in the second state, the second port (P2) and the third port (P3) communicate with each other, and the first port (P1) is closed.

<Outdoor heat exchanger>
The outdoor heat exchanger (13) constitutes a heat source heat exchanger. The outdoor heat exchanger (13) is a fin-and-tube type air heat exchanger. The outdoor fan (12) is located near the outdoor heat exchanger (13). The outdoor fan (12) carries outdoor air. The outdoor heat exchanger exchanges heat between the refrigerant flowing inside the outdoor heat exchanger and the outdoor air carried by the outdoor fan (12).

The outdoor gas side flow path (36) is connected to the gas end of the outdoor heat exchanger (13). An outdoor flow path (O) is connected to the liquid end of the outdoor heat exchanger (13).

<Outdoor flow path>
The outdoor flow path (O) is the outdoor first pipe (o1), the outdoor second pipe (o2), the outdoor third pipe (o3), the outdoor fourth pipe (o4), the outdoor fifth pipe (o5), and the outdoor pipe. Includes 6 pipes (o6), outdoor 7th pipe (o7), and outdoor 8th pipe (o8). One end of the outdoor first pipe (o1) is connected to the liquid end of the outdoor heat exchanger (13). One end of the outdoor second pipe (o2) and one end of the outdoor third pipe (o3) are connected to the other end of the outdoor first pipe (o1), respectively. The other end of the outdoor second pipe (o2) is connected to the top of the gas-liquid separator (15). One end of the outdoor fourth pipe (o4) is connected to the bottom of the gas-liquid separator (15). One end of the outdoor fifth pipe (o5) and the other end of the outdoor third pipe (o3) are connected to the other end of the outdoor fourth pipe (o4). One end of the outdoor sixth pipe (o6) and one end of the outdoor eighth pipe (o8) are connected to the other end of the outdoor fifth pipe (o5). The other end of the outdoor eighth pipe (o8) is connected to the second liquid connecting pipe (4). The other end of the outdoor sixth pipe (o6) is connected to the first liquid connecting pipe (2). One end of the outdoor seventh pipe (o7) is connected in the middle of the outdoor sixth pipe (o6). The other end of the outdoor seventh pipe (o7) is connected in the middle of the outdoor second pipe (o2).

<Decompression mechanism>
The heat source circuit (11) has a first decompression mechanism (14) and a second decompression mechanism (18). The first and second decompression mechanisms (14, 18) decompress the refrigerant flowing out to the utilization unit (50, 60).

The first decompression mechanism (14) is the first outdoor expansion valve (14). The first outdoor expansion valve (14) is an electronic expansion valve whose opening degree is adjusted by driving a pulse motor by a pulse signal from the controller (100). The first outdoor expansion valve (14) is connected to the outdoor first pipe (o1).

The second decompression mechanism (18) is the second outdoor expansion valve (18). The second outdoor expansion valve (18) is an electronic expansion valve whose opening degree is adjusted by driving a pulse motor by a pulse signal from the controller (100). The second outdoor expansion valve (18) is connected to the outdoor eighth pipe (o8).

<Gas-liquid separator>
The gas-liquid separator (15) constitutes a container for storing the refrigerant. The gas-liquid separator (15) is provided downstream of the first outdoor expansion valve (14). In the gas-liquid separator (15), the refrigerant is separated into a gas refrigerant and a liquid refrigerant. The other end of the outdoor second pipe (o2) and one end of the gas vent pipe (37), which will be described later, are connected to the top of the gas-liquid separator (15).

<Main flow path, first branch flow path, second branch flow path>
The outdoor circuit (11) has a main flow path (M), a first branch flow path (o8), and a second branch flow path (o6). The main flow path (M) is composed of an outdoor first pipe (o1), an outdoor second pipe (o2), a gas-liquid separator (15), an outdoor fourth pipe (o4), and an outdoor fifth pipe (o5). .. The first outdoor expansion valve (14) is connected to the outdoor first pipe (o1) in the main flow path (M).

One end of the first branch flow path (o8) is connected to the end of the main flow path (M). The other end of the first branch flow path (o8) is connected to a closing valve to which the second liquid connecting pipe (4) is connected so as to communicate with the cooling unit (60). Specifically, the first branch flow path (o8) is the outdoor eighth pipe (o8). The second outdoor expansion valve (18) is connected to the outdoor eighth pipe (o8).

One end of the second branch flow path (o6) is connected to the end of the main flow path (M). The other end of the second branch flow path (o6) is connected to a closing valve to which the first liquid connecting pipe (2) is connected so as to communicate with the air conditioning unit (50). Specifically, the second branch flow path (o6) is the outdoor sixth pipe (o6).

<Intermediate injection circuit>
The outdoor circuit (11) includes an intermediate injection circuit (49). The intermediate injection circuit (49) is configured so that the refrigerant flowing through the intermediate injection circuit (49) is supplied to the intermediate pressure section between the first compression section (22, 23) and the second compression section (21). Will be done. The intermediate injection circuit (49) includes a first refrigerant pipe (37) and an injection pipe (38).

One end of the injection pipe (38) is connected in the middle of the outdoor fifth pipe (o5). The other end of the injection pipe (38) is connected to the first suction pipe (21a) of the first compressor (21). The injection pipe (38) is provided with a pressure reducing valve (40). The pressure reducing valve (40) is an expansion valve having a variable opening degree.

The first refrigerant pipe (37) is a gas vent pipe (37) connected to the gas-liquid separator (15). In the gas vent pipe (37), the gas refrigerant of the gas-liquid separator (15) flows from the gas-liquid separator (15) between the first compression section (22, 23) and the second compression section (21). It is configured to flow into the road. Specifically, one end of the degassing pipe (37) is connected to the top of the gas-liquid separator (15). The other end of the degassing pipe (37) is connected in the middle of the injection pipe (38). A degassing valve (39) is connected to the degassing pipe (37). The degassing valve (39) is an electronic expansion valve having a variable opening.

<Cooling heat exchanger>
The outdoor circuit (11) comprises a cooling heat exchanger (16). The cooling heat exchanger (16) is a supercooling heat exchanger (16) that cools the refrigerant (mainly the liquid refrigerant) separated by the gas-liquid separator (15). The supercooled heat exchanger (16) is connected between the gas-liquid separator (15) and the second outdoor expansion valve (18). The supercooling heat exchanger (16) has a first flow path (16a) which is a high pressure side flow path and a second flow path (16b) which is a low pressure side flow path. In the supercooling heat exchanger (16), the high-pressure refrigerant flowing through the first flow path (16a) and the decompressed refrigerant flowing through the second flow path (16b) exchange heat.

In the supercooling heat exchanger (16), the refrigerant flowing through the first flow path (16a) is cooled. The first flow path (16a) is connected in the middle of the outdoor fourth pipe (o4), which is a liquid pipe through which the liquid refrigerant of the heat source circuit (11) flows.

The second flow path (16b) is a flow path through which the refrigerant that cools the refrigerant flowing through the first flow path (16a) flows. The second flow path (16b) is included in the intermediate injection circuit (49). Specifically, the second flow path (16b) is connected to the downstream side of the pressure reducing valve (40) in the injection pipe (38). A refrigerant that has been diverted from the first flow path (16a) and depressurized by the pressure reducing valve (40) flows through the second flow path (16b).

<Intercooler>
The intercooler (17) is connected to the intermediate flow path (41). One end of the intermediate flow path (41) is connected to the second discharge pipe (22b) of the second compressor (22) and the third discharge pipe (23b) of the third compressor (23). The other end of the intermediate flow path (41) is connected to the first suction pipe (21a) of the first compressor (21). In other words, the other end of the intermediate flow path (41) is connected to the intermediate pressure portion of the compression element (C).

The intercooler (17) is a fin-and-tube type air heat exchanger. A cooling fan (17a) is arranged in the vicinity of the intercooler (17). The intercooler (17) exchanges heat between the refrigerant flowing inside the intercooler (17) and the outdoor air carried by the cooling fan (17a).

<Oil separation circuit>
The outdoor circuit (11) includes an oil separation circuit (42). The oil separation circuit (42) includes an oil separator (43), a first oil return pipe (44), a second oil return pipe (45), and a third oil return pipe (46). The oil separator (43) is connected to the first discharge pipe (21b) of the first compressor (21). The oil separator (43) separates the oil from the refrigerant discharged from the compression element (C). The inflow end of the first oil return pipe (44) communicates with the oil separator (43). The outflow end of the first oil return pipe (44) is connected to the second suction pipe (22a) of the second compressor (22). The inflow end of the second oil return pipe (45) communicates with the oil separator (43). The outflow end of the second oil return pipe (45) is connected to the inflow end of the intermediate flow path (41). The third oil return pipe (46) has a main return pipe (46a), a cold side branch pipe (46b), and an indoor side branch pipe (46c). The inflow end of the main return pipe (46a) communicates with the oil separator (43). The inflow end of the cold side branch pipe (46b) and the inflow end of the indoor side branch pipe (46c) are connected to the outflow end of the main return pipe (46a). The outflow end of the cold side branch pipe (46b) communicates with the oil pool in the casing of the second compressor (22). The outflow end of the indoor branch pipe (46c) communicates with the oil sump in the casing of the third compressor (23).

The first oil amount control valve (47a) is connected to the first oil return pipe (44). A second oil amount control valve (47b) is connected to the second oil return pipe (45). A third oil amount control valve (47c) is connected to the cold side branch pipe (46b). A fourth oil amount control valve (47d) is connected to the indoor branch pipe (46c).

The oil separated by the oil separator (43) is returned to the second compressor (22) via the first oil return pipe (44). The oil separated by the oil separator (43) is returned to the third compressor (23) via the second oil return pipe (45). The oil separated by the oil separator (43) is returned to the oil sump in each casing of the second compressor (22) and the third compressor (23) via the third oil return pipe (46). ..

<Check valve>
The outdoor circuit (11) includes a first check valve (CV1), a second check valve (CV2), a third check valve (CV3), a fourth check valve (CV4), and a fifth check valve (CV5). ), A sixth check valve (CV6), and a seventh check valve (CV7). The first check valve (CV1) is connected to the first discharge pipe (21b). The second check valve (CV2) is connected to the second discharge pipe (22b). The third check valve (CV3) is connected to the third discharge pipe (23b). The fourth check valve (CV4) is connected to the outdoor second pipe (o2). The fifth check valve (CV5) is connected to the outdoor third pipe (o3). The sixth check valve (CV6) is connected to the outdoor sixth pipe (o6). The 7th check valve (CV7) is connected to the outdoor 7th pipe (o7). These check valves (CV1 to CV7) allow the flow of the refrigerant in the direction of the arrow shown in FIG. 1 and prohibit the flow of the refrigerant in the direction opposite to the arrow.

<Colding unit>
The cooling unit (60) is a first-use unit (60) that cools the inside of the refrigerator. The cooling unit (60) has a cooling fan (62) and a cooling circuit (61). The second liquid connecting pipe (4) is connected to the liquid end of the cooling circuit (61). A second gas connecting pipe (5) is connected to the gas end of the cooling circuit (61).

The cold circuit (61) has a cold expansion valve (63) and a cold heat exchanger (64) in order from the liquid end to the gas end. The cold expansion valve (63) is a second-use expansion valve. The cold expansion valve (63) is composed of an electronic expansion valve having a variable opening.

The cold heat exchanger (64) is a fin-and-tube type air heat exchanger. The cold fan (62) is located in the vicinity of the cold heat exchanger (64). The cold fan (62) conveys the air inside the refrigerator. The cold heat exchanger (64) exchanges heat between the refrigerant flowing inside the cold heat exchanger (64) and the air inside the refrigerator carried by the cold fan (62).

<Air conditioning unit>
The air conditioning unit (50) is a second utilization unit (50) installed indoors. The air conditioning unit (50) has a higher evaporation temperature of the refrigerant than the cooling unit (60). The air conditioning unit (50) has an indoor fan (52) and an indoor circuit (51). The first liquid connecting pipe (2) is connected to the liquid end of the indoor circuit (51). The first gas connecting pipe (3) is connected to the gas end of the indoor circuit (51).

The indoor circuit (51) has an indoor expansion valve (53) and an indoor heat exchanger (54) in order from the liquid end to the gas end. The indoor expansion valve (53) is a first-use expansion valve. The indoor expansion valve (53) is an electronic expansion valve having a variable opening.

The indoor heat exchanger (54) is a fin-and-tube type air heat exchanger. The indoor fan (52) is located in the vicinity of the indoor heat exchanger (54). The indoor fan (52) carries indoor air. The indoor heat exchanger (54) exchanges heat between the refrigerant flowing inside the indoor heat exchanger (54) and the indoor air carried by the indoor fan (52).

<Sensor>
The refrigerating device (1) has various sensors. Various sensors include a high pressure pressure sensor (71), an intermediate pressure pressure sensor (72), a first low pressure pressure sensor (73), a second low pressure pressure sensor (74), a two-phase refrigerant pressure sensor (75), and pressure acquisition. Includes part (48).

The high pressure pressure sensor (71) detects the pressure (high pressure pressure (HP)) of the discharged refrigerant of the first compressor (21). The intermediate pressure pressure sensor (72) is the pressure of the refrigerant in the intermediate flow path (41), in other words, between the first compressor (21) and the second compressor (22) and the third compressor (23). Detects the pressure of the refrigerant (intermediate pressure (MP)). The first low pressure pressure sensor (73) detects the pressure of the intake refrigerant sucked into the second compressor (22) (first low pressure pressure (LP1)). The second low pressure pressure sensor (74) detects the pressure of the intake refrigerant sucked into the third compressor (23) (second low pressure pressure (LP2)). The two-phase refrigerant pressure sensor (75) detects the pressure of the liquid refrigerant (two-phase refrigerant pressure (RP)) of the gas-liquid separator (15).

The pressure acquisition unit of this embodiment is an outlet pressure sensor (48). The outlet pressure sensor (48) detects the pressure (outlet pressure (SP)) after decompression by the second outdoor expansion valve (18) in the outdoor eighth pipe (o8).

The physical quantities detected by other sensors include the temperature of the high-pressure refrigerant, the temperature of the low-pressure refrigerant, the temperature of the intermediate-pressure refrigerant, the temperature of the refrigerant in the outdoor heat exchanger (13), the temperature of the refrigerant in the cold heat exchanger (64), and so on. Examples include the temperature of the outdoor air and the temperature of the internal air.

<controller>
The controller (100) includes a microcomputer mounted on a control board and a memory device (specifically, a semiconductor memory) for storing software for operating the microcomputer. The controller (100) controls various devices of the refrigerating device (1) based on the detection signals of various sensors.

As shown in FIG. 2, the controller (100) which is a control unit includes an outdoor controller (101) provided in the heat source unit (10), an indoor controller (102) provided in the air conditioner unit (50), and a cold controller (102). It has a cooling controller (103) provided in the installation unit (60). The outdoor controller (101) can communicate with the indoor controller (102) and the cold controller (103). The controller (100) is connected to various pressure sensors such as an outlet pressure sensor (48) and a high pressure pressure sensor (71), various temperature sensors, and the like by a communication line. The controller (100) is connected to the components of the refrigerant circuit (6) including the first outdoor expansion valve (14), the second outdoor expansion valve (18), and the like by a communication line.

The outdoor controller (101) controls the second outdoor expansion valve (18) so that the pressure acquired by the outlet pressure sensor (48) becomes the target pressure. The target pressure is a pressure lower than the design pressure of the cooling unit (60).

The outdoor controller (101) controls the refrigerant to be compressed to a critical pressure or higher by the compression element (C). The outdoor controller (101) controls the first outdoor expansion valve (14) so that the two-phase refrigerant pressure (RP) is reduced to the subcritical pressure.

The outdoor controller (101) controls the cooling capacity of the supercooling heat exchanger (16). Specifically, the outdoor controller (101) controls the pressure reducing valve (40) so that the refrigerant flowing out of the second outdoor expansion valve (18) maintains a liquid state.

-Driving operation-
The operating operation of the refrigerating apparatus (1) will be described in detail. The operation of the refrigerating apparatus (1) includes a cooling operation, a cooling operation, a cooling / cooling operation, a heating operation, a heating / cooling operation, and a defrost operation.

In the cold operation, the cold unit (60) is operated and the air conditioning unit (50) is stopped. In the cooling operation, the cooling unit (60) is stopped and the air conditioning unit (50) cools. In the cooling / cooling operation, the cooling unit (60) is operated and the air conditioning unit (50) cools. In the heating operation, the cooling unit (60) stops and the air conditioning unit (50) heats. In the heating / cooling operation, the cooling unit (60) is operated and the air conditioning unit (50) heats. In the defrost operation, the cooling unit (60) is operated to melt the frost on the surface of the outdoor heat exchanger (13). The heating / cooling operation is performed under conditions where the required heating capacity of the air conditioning unit (50) is relatively large.

<Cold operation>
In the cold operation shown in FIG. 3, the first three-way valve (TV1) is in the second state and the second three-way valve (TV2) is in the first state. The first outdoor expansion valve (14) and the second outdoor expansion valve (18) are opened at a predetermined opening degree, and the opening degree of the cold expansion valve (63) is adjusted by superheat degree control. The indoor expansion valve (53) is fully closed, and the opening degree of the pressure reducing valve (40) is adjusted as appropriate. The outdoor fan (12), the cooling fan (17a), and the cooling fan (62) are operated, and the indoor fan (52) is stopped. The first compressor (21) and the second compressor (22) are operated, and the third compressor (23) is stopped. In the cold operation, a refrigeration cycle is performed in which the outdoor heat exchanger (13) serves as a radiator and the cold heat exchanger (64) serves as an evaporator.

As shown in FIG. 3, the refrigerant compressed by the second compressor (22) is cooled by the intercooler (17) and then sucked into the first compressor (21). The refrigerant compressed by the first compressor (21) is dissipated by the outdoor heat exchanger (13) and then decompressed by the first outdoor expansion valve (14) to become a refrigerant lower than the second pressure (critical pressure). Become. This refrigerant flows through the gas-liquid separator (15) and is cooled by the supercooling heat exchanger (16). The refrigerant cooled by the supercooling heat exchanger (16) is depressurized by the second outdoor expansion valve (18). The decompressed refrigerant is decompressed by the cold expansion valve (63) and then evaporated by the cold heat exchanger (64). As a result, the air inside the refrigerator is cooled. The refrigerant evaporated in the cooling heat exchanger (16) is sucked into the second compressor (22) and compressed again.

<Cooling operation>
In the cooling operation shown in FIG. 4, the first three-way valve (TV1) is in the second state and the second three-way valve (TV2) is in the first state. The first outdoor expansion valve (14) is opened at a predetermined opening degree, and the second outdoor expansion valve (18) and the cold expansion valve (63) are fully closed. The opening degrees of the indoor expansion valve (53) and the pressure reducing valve (40) are adjusted as appropriate. The outdoor fan (12), the cooling fan (17a), and the indoor fan (52) are operated, and the cooling fan (62) is stopped. The first compressor (21) and the third compressor (23) are operated, and the second compressor (22) is stopped. In the cooling operation, a refrigeration cycle is performed in which the outdoor heat exchanger (13) serves as a radiator and the indoor heat exchanger (54) serves as an evaporator.

As shown in FIG. 4, the refrigerant compressed by the third compressor (23) is cooled by the intercooler (17) and then sucked into the first compressor (21). The refrigerant compressed by the first compressor (21) dissipates heat in the outdoor heat exchanger (13), flows through the gas-liquid separator (15), and is cooled by the supercooling heat exchanger (16). The refrigerant cooled by the cooling heat exchanger (16) is decompressed by the indoor expansion valve (53) and then evaporated by the indoor heat exchanger (54). As a result, the indoor air is cooled. The refrigerant evaporated in the indoor heat exchanger (54) is sucked into the third compressor (23) and compressed again.

<Cooling / cooling operation>
In the cooling / cooling operation shown in FIG. 5, the first three-way valve (TV1) is in the second state and the second three-way valve (TV2) is in the first state. The first outdoor expansion valve (14) and the second outdoor expansion valve (18) are opened at a predetermined opening degree. The opening degrees of the cold expansion valve (63), the indoor expansion valve (53), and the pressure reducing valve (40) are adjusted as appropriate. The outdoor fan (12), cooling fan (17a), cooling fan (62), and indoor fan (52) are operated. The first compressor (21), the second compressor (22), and the third compressor (23) are operated. In the cooling / cooling operation, a refrigeration cycle is performed in which the outdoor heat exchanger (13) serves as a radiator and the cold heat exchanger (64) and the indoor heat exchanger (54) serve as evaporators.

As shown in FIG. 5, the refrigerants compressed by the second compressor (22) and the third compressor (23) are cooled by the intercooler (17) and then transferred to the first compressor (21). Inhaled. The refrigerant compressed by the first compressor (21) is dissipated by the outdoor heat exchanger (13) and then decompressed by the first outdoor expansion valve (14) to become a refrigerant lower than the second pressure (critical pressure). Become. This refrigerant flows through the gas-liquid separator (15) and is cooled by the supercooling heat exchanger (16). The refrigerant cooled by the supercooling heat exchanger (16) is divided into the outdoor sixth pipe (o8) and the outdoor sixth pipe (o6). The refrigerant diverted to the outdoor sixth pipe (o6) flows into the air conditioning unit (50). The refrigerant decompressed by the indoor expansion valve (53) evaporates by the indoor heat exchanger (54). The refrigerant evaporated in the indoor heat exchanger (54) is sucked into the third compressor (23) and compressed again. The refrigerant flowing into the outdoor eighth pipe (o8) is depressurized by the second outdoor expansion valve (18). This refrigerant is depressurized by the cold expansion valve (63) and then evaporated by the cold heat exchanger (64). The refrigerant evaporated in the cold heat exchanger (64) is sucked into the second compressor (22) and compressed again.

<Heating operation>
In the heating operation shown in FIG. 6, the first three-way valve (TV1) is in the first state and the second three-way valve (TV2) is in the second state. The indoor expansion valve (53) is opened at a predetermined opening degree, and the second outdoor expansion valve (18) and the cold expansion valve (63) are fully closed. The opening degrees of the first outdoor expansion valve (14) and the pressure reducing valve (40) are appropriately adjusted. The outdoor fan (12) and the indoor fan (52) are operated, and the cooling fan (17a) and the cooling fan (62) are stopped. The first compressor (21) and the third compressor (23) are operated, and the second compressor (22) is stopped. In the heating operation, a refrigeration cycle is performed in which the indoor heat exchanger (54) serves as a radiator and the outdoor heat exchanger (13) serves as an evaporator.

As shown in FIG. 6, the refrigerant compressed by the third compressor (23) is sucked into the first compressor (21) after passing through the intercooler (17). The refrigerant compressed by the first compressor (21) dissipates heat by the indoor heat exchanger (54). As a result, the indoor air is heated. The refrigerant dissipated by the indoor heat exchanger (54) flows through the gas-liquid separator (15) and is cooled by the cooling heat exchanger (16). The refrigerant cooled by the cooling heat exchanger (16) is decompressed by the first outdoor expansion valve (14) and then evaporated by the outdoor heat exchanger (13). The refrigerant evaporated in the outdoor heat exchanger (13) is sucked into the third compressor (23) and compressed again.

<Heating / cooling operation>
In the heating / cooling operation shown in FIG. 7, the first three-way valve (TV1) is in the first state and the second three-way valve (TV2) is in the second state. The indoor expansion valve (53) is opened at a predetermined opening. The opening degrees of the cold expansion valve (63), the first outdoor expansion valve (14), the second outdoor expansion valve (18), and the pressure reducing valve (40) are appropriately adjusted. The outdoor fan (12), the cooling fan (62), and the indoor fan (52) are operated. The cooling fan (17a) is stopped. The first compressor (21), the second compressor (22), and the third compressor (23) are operated. In the heating / cooling operation, a refrigeration cycle is performed in which the indoor heat exchanger (54) serves as a radiator and the cold heat exchanger (64) and the outdoor heat exchanger (13) serve as evaporators.

As shown in FIG. 7, the refrigerants compressed by the second compressor (22) and the third compressor (23) are sucked into the first compressor (21) after passing through the intercooler (17). Will be done. The refrigerant compressed by the first compressor (21) dissipates heat by the indoor heat exchanger (54). As a result, the indoor air is heated. The refrigerant dissipated by the indoor heat exchanger (54) flows through the gas-liquid separator (15) and is cooled by the cooling heat exchanger (16). A part of the refrigerant cooled by the cooling heat exchanger (16) is decompressed by the first outdoor expansion valve (14) and then evaporated by the outdoor heat exchanger (13). The refrigerant evaporated in the outdoor heat exchanger (13) is sucked into the third compressor (23) and compressed again.

The rest of the refrigerant cooled by the cooling heat exchanger (16) is decompressed by the second outdoor expansion valve (18). This refrigerant evaporates in the cold heat exchanger (64). As a result, the air inside the refrigerator is cooled. The refrigerant evaporated in the cold heat exchanger (64) is sucked into the second compressor (22) and compressed again.

<Defrost operation>
In the defrost operation, the same operation as the cooling operation shown in FIG. 4 is performed. In the defrost operation, the refrigerant compressed by the second compressor (22) and the first compressor (21) dissipates heat by the outdoor heat exchanger (13). As a result, the frost on the surface of the outdoor heat exchanger (13) is heated from the inside. The refrigerant used for defrosting the outdoor heat exchanger (13) evaporates in the indoor heat exchanger (54), is sucked into the second compressor (22), and is compressed again.

-Issues of refrigeration equipment equipped with air conditioning unit and cooling unit-
The outline of the cooling / cooling refrigeration cycle of a refrigerating apparatus including an air conditioning unit and a cooling unit and a two-stage compression type refrigerant circuit in which carbon dioxide is used as a refrigerant will be described with reference to FIGS. 8 and 9.

The refrigerant compressed by the compression element (C) has a high pressure (HP). This high-pressure refrigerant dissipates heat when passing through the outdoor heat exchanger (13), and then is depressurized by the first outdoor expansion valve (14). The pressure of the refrigerant after this decompression becomes the two-phase refrigerant pressure (RP). The two-phase refrigerant pressure (RP) refrigerant is separated into a liquid refrigerant and a gas refrigerant by the gas-liquid separator (15), and the liquid refrigerant is supercooled by the supercooling heat exchanger (16). The supercooled liquid refrigerant is divided into a cooling unit (60) and an air conditioning unit (50). The liquid refrigerant directed to the cold heat exchanger (64) is depressurized by the cold expansion valve (63) to become the first low pressure (LP1). The liquid refrigerant directed to the indoor heat exchanger (54) is depressurized by the indoor expansion valve (53) to become the second low pressure pressure (LP2). The refrigerant that has reached the first low pressure (LP1) is sucked into the second compressor (22). The refrigerant that has reached the second low pressure (LP2) is sucked into the third compressor (23). The refrigerant compressed by the second compressor (22) and the third compressor (23) merges with the refrigerant flowing through the injection pipe (38) to reach an intermediate pressure (MP). This intermediate pressure (MP) is adjusted by the pressure reducing valve (40) of the intermediate injection circuit (49).

Here, as shown in FIG. 8, for example, the high pressure pressure (HP) is 9.0 MPa, the two-phase refrigerant pressure (RP) is 6.5 MPa, the intermediate pressure (MP) is 5.0 MPa, and the first low pressure pressure (LP1). ) Is 2.5 MPa, and the second low pressure pressure (LP2) is 3.8 MPa. When the design pressure of the cooling unit (60) is 6.0 MPa, it is necessary to lower the two-phase refrigerant pressure (RP) of the refrigerant flowing into the cooling expansion valve (63) from 6.0 MPa (design pressure). However, when both the two-phase refrigerant pressure (RP) and the intermediate pressure (MP) are lowered below the design pressure, the compression ratio of the second compression section (21) on the higher stage side becomes lower than the design pressure, as shown in FIG. It becomes larger than the compression ratio of the first compression part (22, 23), and there arises a problem that the load on the second compression part (21) becomes large. In other words, as will be described later, the balance between the first compression unit (22, 23) and the second compression unit (21) is lost.

Furthermore, it is desirable that the refrigerant flowing into the indoor expansion valve (53) and the cold expansion valve (63) is in a liquid state. This is because if a part of the refrigerant is vaporized, the refrigerant flowing from each expansion valve (53, 63) to each heat exchanger (54, 64) may flow unevenly. Therefore, in the present embodiment, the refrigerant flowing out of the gas-liquid separator (15) is supercooled in the supercooling heat exchanger (16) in order to maintain the liquid state. In the supercooling heat exchanger (16), the pressure reducing valve (40) is set so that the refrigerant flowing through the first flow path (16a) drops by, for example, 10 ° C. on the upstream side and the downstream side of the first flow path (16a). By controlling, the refrigerant flowing into the second flow path (16b) is depressurized by 1.5 MPa (equivalent to 10 ° C.). In this way, in order to secure the cooling capacity of the supercooling heat exchanger (16), the differential pressure between the two-phase refrigerant pressure (RP) and the intermediate pressure (MP) is set to 1.5 MPa. As a result, for example, when the two-phase refrigerant pressure (RP) is set to 5.5 MPa, which is lower than the design pressure (6.0 MPa) of the cooling unit, as shown in FIG. 9, the intermediate pressure (MP) becomes 4.0 MPa. .. When the intermediate pressure (MP) drops to 4.0 MPa, the second low pressure pressure (LP2) of the air conditioning unit (50) is 3.8 MPa, so the difference between the intermediate pressure (MP) and the second low pressure pressure (LP2). The pressure decreases. For this reason, the amount of circulation of the refrigerant sucked into the third compressor (23) is reduced, which causes a problem that the air conditioning capacity of the air conditioning unit (50) cannot be secured.

On the other hand, if the intermediate pressure (MP) is set high in order to sufficiently secure the differential pressure between the intermediate pressure (MP) and the second low pressure pressure (LP2), the two-phase refrigerant pressure (RP) also increases accordingly. As a result, the two-phase refrigerant pressure (RP) exceeds the design pressure (6.0 MPa) of the cooling unit.

In consideration of such a problem, the refrigerating apparatus (1) of the present embodiment performs cooling / cooling operation while ensuring the capacity of the air conditioning unit (50) without lowering the two-phase refrigerant pressure (RP). .. Specifically, a second outdoor expansion valve (18) and an outlet pressure sensor (48) are provided in the outdoor eighth pipe (o8) communicating with the second liquid communication pipe (4) of the cooling unit (60). The controller (100) has a second outdoor expansion valve (18) (second decompression mechanism) so that the pressure detected by the outlet pressure sensor (48) becomes a target pressure lower than the design pressure of the cooling unit (60). ) Is controlled. As a result, the amount of refrigerant circulating in the air conditioning unit (50) is secured without lowering the intermediate pressure (MP), and the outlet pressure (SP) is lowered to correspond to the design pressure of the cooling unit (60).

An example of control of the second outdoor expansion valve (18) will be specifically described with reference to FIG. Here, the design pressure of the cooling unit (60) is 6.0 MPa. The target pressure is 5.0 MPa or more and less than 6.0 MPa. The description will be made based on the state in which the cooling / cooling operation is performed (the state shown in FIG. 5).

In step ST1, the outdoor controller (101) determines whether the cooling unit (60) starts operation. Specifically, when the outdoor controller (101) receives the operation request of the cooling unit (60) from the cooling controller (103), the process proceeds to step ST2. When the outdoor controller (101) does not receive the operation request of the cold unit (60) from the cold controller (103), it shifts to the start control (A) of the first compressor (21) of FIG.

In step ST2, the outdoor controller (101) determines whether the two-phase refrigerant pressure (RP) of the gas-liquid separator is higher than the predetermined pressure. This predetermined pressure is a pressure (7.0 MPa) at which the refrigerant can be separated into a gas and a liquid when the refrigerant is carbon dioxide. If the two-phase refrigerant pressure (RP) is higher than the predetermined pressure (7.0 MPa), the process proceeds to step ST3. When the two-phase refrigerant pressure (RP) is equal to or lower than the predetermined pressure (7.0 MPa), the process proceeds to step ST4.

In step ST3, the outdoor controller (101) opens the degassing valve (39). This lowers the two-phase refrigerant pressure (RP) of the gas-liquid separator (15). The gas refrigerant in the gas-liquid separator (15) flows through the degassing pipe (37) and is introduced into the intermediate pressure section (21a).

In step ST4, the outdoor controller (101) adjusts the second outdoor expansion valve (18) to a predetermined opening degree. This predetermined opening degree is, for example, 240 pls (pulses). When the opening degree of the second outdoor expansion valve (18) is fully open, it is 480 pls. 240pls is half the opening.

In step ST5, the outlet pressure sensor (48) detects the outlet pressure (SP) of the refrigerant flowing out to the cooling unit. Specifically, the outlet pressure sensor (48) detects the pressure of the refrigerant decompressed by the second outdoor expansion valve (18). If the outlet pressure (SP) is the target pressure (5.0 MPa or more and less than 6.0 MPa), the outdoor controller (101) ends this control and returns to the main control flow (not shown) as it is. If the outlet pressure (SP) is not the target pressure (5.0 MPa or more and less than 6.0 MPa), the process proceeds to step ST6.

In step ST6, the outdoor controller (101) determines whether the outlet pressure (SP) is less than 5.0 MPa. If the outlet pressure (SP) is less than 5.0 MPa, the process proceeds to step ST7. If the outlet pressure (SP) is not less than 5.0 MPa, the process proceeds to step ST9.

In step ST7, the outdoor controller (101) determines whether the second outdoor expansion valve (18) has a predetermined opening or more. The predetermined opening degree is, for example, 480 pls (fully open). If the second outdoor expansion valve (18) is fully open, the process proceeds to step ST5. In step ST5, the outdoor controller (101) again determines whether the outlet pressure (SP) is at the target pressure (5.0 MPa or more and less than 6.0 MPa). Actually, in step ST4, the opening degree of the second outdoor expansion valve (18) is set to 240 pls. Therefore, since the opening degree of the second outdoor expansion valve (18) is smaller than 480 pls, the process proceeds to step ST8.

In step ST8, the outdoor controller (101) increases the opening degree of the second outdoor expansion valve (18) from the current opening degree. Specifically, the outdoor controller (101) increases the opening degree of the second outdoor expansion valve (18) by 2 pls from the current opening degree. After that, the process proceeds to step ST5. In step ST5, the outdoor controller (101) again determines whether the outlet pressure (SP) is at the target pressure (5.0 MPa or more and less than 6.0 MPa).

In step ST9, the outlet pressure (SP) is 6.0 MPa or more. The outdoor controller (101) determines whether the opening degree of the second outdoor expansion valve (18) is smaller than the predetermined opening degree. The predetermined opening degree is, for example, 100 pls. If the opening degree of the second outdoor expansion valve (18) is less than 100 pls, the process proceeds to step ST10. If the opening degree of the second outdoor expansion valve (18) is 100 pls or more, the process proceeds to step ST11.

In step ST11, the outdoor controller (101) reduces the opening degree of the second outdoor expansion valve (18) from the current opening degree. Specifically, the outdoor controller (101) reduces the opening degree of the second outdoor expansion valve (18) by 2 pls from the current opening degree. After that, the process proceeds to step ST5. In step ST5, the outdoor controller (101) again determines whether the outlet pressure (SP) is at the target pressure (5.0 MPa or more and less than 6.0 MPa).

In step ST11, the outdoor controller (101) stops the operation of the second compressor (22). The outdoor controller (101) transmits a signal to the cold controller (103) that the operation of the second compressor (22) is OFF. Upon receiving this signal, the cooling controller (103) stops the operation of the cooling unit (60). After that, the process shifts to the start control (A) of the first compressor (21).

The start control (A) of the first compressor (21) will be described with reference to FIG. The outdoor controller (101) starts start control of the first compressor (21). In step ST21, the outdoor controller (101) sets the opening degree of the second outdoor expansion valve (18) to a predetermined opening degree. This predetermined opening degree is, for example, 100 pls.

In step ST22, the outdoor controller (101) determines whether the two-phase refrigerant pressure (RP) is greater than the design pressure (6.0 MPa) of the cooling unit (60). If the two-phase refrigerant pressure (RP) is greater than the design pressure (6.0 MPa), the process proceeds to step ST23. If the two-phase refrigerant pressure (RP) is less than or equal to the design pressure (6.0 MPa), the two-phase refrigerant pressure (RP) is sufficiently low, so that the outdoor controller (101) is the first compressor (21). Exit the start control (A) and return to the main control flow (not shown) as it is.

In step ST23, the pressure inside the gas-liquid separator (15) is high, so the outdoor controller (101) operates the first compressor (21). When the first compressor (21) is operated, the gas refrigerant of the gas-liquid separator (15) is sucked into the first compressor (21). This reduces the pressure in the gas-liquid separator (15). The outdoor controller (101) ends this control and returns to the main control flow (not shown).

-Effect of Embodiment 1-
In the present embodiment, the heat source unit (10) is a utilization unit (50) having a first utilization unit (60) and a second utilization unit (50) having a higher refrigerant evaporation temperature than the first utilization unit (60). , 60) The heat source circuit (11) that is connected to the utilization circuit (51, 61) and constitutes the refrigerant circuit (6) that performs the refrigeration cycle, and the control unit (100) that controls the heat source circuit (11). Be prepared. The heat source circuit (11) is the compression element having a first compression unit (22, 23) and a second compression unit (21) that further compresses the refrigerant compressed by the first compression unit (22, 23). (C), a radiator (13), a first decompression mechanism (14), and a main flow path (M) connected to the downstream side of the radiator (13) and provided with the first decompression mechanism (14). , The first branch flow path (o8) connected to the end of the main flow path (M) and communicating with the first utilization unit (60), and the end of the main flow path (M). The second branch flow path (o6) communicating with the second utilization unit (50), one end is connected to the main flow path (M), and the other end is the first compression section (22, 23) and the second compression. An intermediate injection circuit (49) connected between the parts (21) and into which the refrigerant decompressed by the first decompression mechanism (14) flows in, and a second decompression mechanism provided in the first branch flow path (o8). (18) and.

In this configuration, the pressure of the refrigerant flowing into the air conditioning unit (50) is adjusted by the first outdoor expansion valve (14). On the other hand, the pressure of the refrigerant flowing into the cooling unit (60) is adjusted by the first outdoor expansion valve (14) and the second outdoor expansion valve (18). As a result, for example, as shown in FIG. 12, when the design pressure of the cooling unit (60) is 6.0 MPa, it is supplied to the cooling unit (60) by the second outdoor expansion valve (18). The refrigerant can be adjusted to the target pressure (outlet pressure (SP)) of 5.5 MPa. Therefore, it is not necessary to reduce the two-phase refrigerant pressure (RP) to the target pressure by the first outdoor expansion valve (14). As a result, the intermediate pressure (MP) does not decrease, so that the differential pressure between the second low pressure pressure (LP2) and the intermediate pressure (MP) can be sufficiently secured. As a result, the refrigerant easily flows from the heat source unit (10) to the air conditioning unit (50), and the cooling capacity of the air conditioning unit (50) can be secured.

In addition, since it is not necessary to reduce the intermediate pressure (MP), it is suppressed that the compression ratio of the refrigerant in the second compression section (21) becomes larger than the compression ratio of the refrigerant in the first compression section (22, 23). To. As a result, the burden on the second compression unit (first compressor (21)) can be reduced.

In addition, the refrigerant decompressed by the pressure reducing valve (40) can be introduced between the first compression unit (22, 23) and the second compression unit (21) via the intermediate injection circuit (49). As a result, it is possible to prevent the balance of the compression ratios of the first compression section (22, 23) and the second compression section (21) from being lost.

In the present embodiment, the heat source circuit (outdoor circuit (11)) detects or estimates the pressure of the refrigerant after decompression by the second decompression mechanism (second outdoor expansion valve (18)). To be equipped. The second decompression mechanism (18) is a valve whose opening degree can be adjusted, and the control unit (controller (100)) uses the pressure detected or estimated by the pressure acquisition unit (48) as the target pressure. As described above, the opening degree of the second decompression mechanism (18) is controlled.

With this configuration, the pressure of the refrigerant supplied to the cooling unit (60) can be adjusted to the target pressure. Therefore, the target pressure can be freely set according to the cooling unit (60). This makes it possible to make the heat source unit (10) compatible with various types of cooling units (60).

In the present embodiment, the heat source circuit (outdoor circuit (11)) includes a gas-liquid separator (15). The intermediate injection circuit (49) includes a first refrigerant pipe (37) connected to the gas-liquid separator (15). In the first refrigerant pipe (37), the gas refrigerant in the gas-liquid separator (15) is transferred from the gas-liquid separator (15) to the first compression section (22, 23) and the second compression section (the second compression section (15). It is configured to flow into the flow path between 21).

In this configuration, the gas-liquid separator (15) and the intermediate pressure section (21a) communicate with each other by the degassing pipe (37). As a result, when the pressure in the gas-liquid separator (15) becomes high, the gas refrigerant in the gas-liquid separator (15) can flow into the intermediate pressure portion (21a). This makes it possible to reduce the pressure inside the gas-liquid separator (15). Further, by lowering the pressure in the gas-liquid separator (15), the refrigerant easily flows into the gas-liquid separator (15).

In the present embodiment, the heat source circuit (11) includes a cooling heat exchanger (16) connected between the first decompression mechanism (14) and the second decompression mechanism (18). The cooling heat exchanger (16) has a first flow path (16a) connected to a liquid pipe through which the liquid refrigerant of the heat source circuit (11) flows, and a first flow path (16a) in which the decompressed refrigerant flows from the liquid pipe. It has two flow paths (16b), and is configured to cool the refrigerant of the first flow path (16a) by the refrigerant of the second flow path (16b). The second flow path (16b) constitutes the intermediate injection circuit (49).

In this configuration, the refrigerant flowing through the first flow path (16a) is depressurized by the pressure reducing valve (40) and flows into the second flow path (16b). As a result, in the supercooling heat exchanger (16), the refrigerant in the first flow path (16a) can be cooled by the refrigerant in the second flow path (16b).

In the present embodiment, the control unit (controller (100)) controls the cooling capacity of the cooling heat exchanger (16) so that the refrigerant flowing out of the second decompression mechanism (18) is in a liquid state.

In this configuration, the outdoor controller (101) controls the pressure reducing valve (40) so that the refrigerant flowing out of the second outdoor expansion valve (18) is in a liquid state. This makes it possible to increase the enthalpy difference of the refrigerant between the inlet and outlet of the cold heat exchanger (64). As a result, the cooling capacity of the cooling unit (60) can be increased.

In addition, gasification of the refrigerant supplied to the cooling unit (60) can be suppressed. As a result, it is possible to suppress the uneven flow of the refrigerant flowing from the cold expansion valve (63) of the cold unit (60) to the cold heat exchanger (64), and eventually the refrigerant evaporates in the cold heat exchanger (64). It is possible to suppress the decrease in ability.

In the present embodiment, the control unit (100) performs a refrigeration cycle in which the refrigerant is compressed to a critical pressure or higher by the compression element (C) and depressurized to a subcritical pressure by the first decompression mechanism (14). The refrigerant circuit (6) is controlled.

In this configuration, the refrigerant expanded by the first outdoor expansion valve (14) and whose temperature has dropped flows into the gas-liquid separator. As a result, for example, even if the outside air temperature is high, the pressure rise in the gas-liquid separator is suppressed, and the refrigerant easily flows into the gas-liquid separator.

-Modification of Embodiment 1-
As shown in FIG. 13, the heat source unit (10) of the first embodiment includes a main heat source unit (10a) and an auxiliary unit (10b) separated from the main heat source unit (10a), and includes an auxiliary unit (10b). ) May include a second outdoor expansion valve (18). As a result, the auxiliary unit (10b) provided with the second outdoor expansion valve (18) can be separated from the main heat source unit (10a). The auxiliary unit (10b) may further include an outlet pressure sensor (48).

<< Embodiment 2 >>
The second embodiment will be described. The refrigerating apparatus (1) of the second embodiment is a modification of the refrigerating apparatus (1) of the first embodiment in which the control of the second outdoor expansion valve (18) performed by the controller (100) is changed. Here, the refrigerating apparatus (1) of the present embodiment will be described as being different from the refrigerating apparatus (1) of the first embodiment.

In the control of the second outdoor expansion valve (18) of the present embodiment, the pressure acquisition unit (48) estimates the refrigerant pressure on the outlet side of the second outdoor expansion valve (18) calculated by various equations. The second outdoor expansion valve (18) is controlled based on the value of the refrigerant pressure on the outlet side of the second outdoor expansion valve (18) estimated by the pressure acquisition unit (48).

The control of the second outdoor expansion valve (18) of the present embodiment will be described with reference to FIG. Similar to the above embodiment, the first pressure (design pressure) of the cooling unit (60) is 6.0 MPa. The pressure lower than the first pressure (target pressure) shall be 5.0 MPa or more and less than 6.0 MPa. The description will be made based on the state in which the cooling / cooling operation is performed (the state shown in FIG. 5).

In step ST31, the outdoor controller (101) determines whether the cooling unit (60) starts operation. Specifically, when the outdoor controller (101) receives the operation request of the cooling unit (60) from the cooling controller (103), the process proceeds to step ST32.

In step ST32, the outdoor controller (101) determines whether the two-phase refrigerant pressure (RP) is higher than the predetermined pressure. This predetermined pressure is, for example, a pressure (7.0 MPa) at which the refrigerant can be separated into a gas and a liquid when the refrigerant is carbon dioxide. When the two-phase refrigerant pressure (RP) is higher than the predetermined pressure (7.0 MPa), the process proceeds to step ST33. When the two-phase refrigerant pressure (RP) is equal to or lower than the predetermined pressure (7.0 MPa), the process proceeds to step ST34.

In step ST33, the second pressure is higher than the predetermined pressure (7.0 MPa), so the outdoor controller (101) opens the degassing valve (39). This lowers the two-phase refrigerant pressure (RP) of the gas-liquid separator (15). The gas refrigerant in the gas-liquid separator (15) flows through the degassing pipe (37) and is introduced into the intermediate pressure section (21a).

In step ST34, the outdoor controller (101) adjusts the second outdoor expansion valve (18) to a predetermined opening degree. This predetermined opening degree is, for example, 240 pls.

In step ST35, the outdoor controller (101) is in the state of the refrigerant sucked into the second compressor (22) (refrigerant flow rate, first low pressure pressure (LP1), refrigerant temperature on the suction side of the second compressor (22)). The refrigerant density (ρ) is calculated from.

In step ST36, the outdoor controller (101) calculates the refrigerant circulation amount (G1) of the second compressor (22) from the rotation speed of the second compressor (22). Specifically, it is expressed by refrigerant circulation amount (G1) = compressor push-off amount (V) × refrigerant density (ρ) × compressor volumetric efficiency (ηv) × rotation speed (n1) / 3600/106.

In step ST37, the outdoor controller (101) calculates the required decompression amount (ΔP). Specifically, it is represented by the amount of reduced pressure (ΔP) = two-phase refrigerant pressure (RP)-(6.0 Mpa + α). Here, α is an arbitrary number.

In step ST38, the outdoor controller (101) calculates the required Cv value of the second outdoor expansion valve (18). The Cv value indicates the flow rate of the refrigerant passing per unit time when the second outdoor expansion valve (18) is fully opened. Specifically, it is represented by Cv value = refrigerant circulation amount (G1) × (coefficient / refrigerant density (ρ) / decompression amount (ΔP)) 0.5 × 103. The Cv value is, in short, an index indicating the ease of flow of the refrigerant in the second outdoor expansion valve (18).

In step ST39, the outdoor controller (101) calculates the Cv value from pls indicating the current opening degree of the second outdoor expansion valve (18). The Cv value at this time is Cv1.

In step ST40, the outdoor controller (101) determines whether or not the value obtained by subtracting Cv1 from the Cv value is −0.2 or more and 0.2 or less. When the value obtained by subtracting Cv1 from the Cv value is −0.2 or more and 0.2 or less, the outdoor controller (101) estimates that the outlet pressure (SP) is the target pressure. The outdoor controller (101) ends this control and returns to the main control flow (not shown) as it is. If the value obtained by subtracting Cv1 from the Cv value is −0.2 or more and not 0.2 or less, the process proceeds to step ST41.

As described above, in steps ST35 to ST40, the outdoor controller (101) calculates the Cv value and Cv1. In the following steps, the outdoor controller (101) sets the opening degree of the second outdoor expansion valve (18).

In step ST41, the outdoor controller (101) determines whether or not the value obtained by subtracting Cv1 from the Cv value is less than −0.2. If the Cv value minus Cv1 is less than -0.2, the outdoor controller (101) does not presume that the outlet pressure (SP) is the target pressure. In this case, the process proceeds to step ST42.

In step ST42, the outdoor controller (101) reduces the opening degree of the second outdoor expansion valve (18) from the current opening degree. Specifically, the outdoor controller (101) further reduces the opening degree of the second outdoor expansion valve (18) by 2 pls from the current opening degree. After that, the process proceeds to step ST35. In step ST35, the outdoor controller (101) recalculates the outlet pressure (SP).

In step ST41, if the value obtained by subtracting Cv1 from the Cv value is not less than −0.2, the outdoor controller (101) determines that the value obtained by subtracting Cv1 from the Cv value is greater than 0.2.

In step ST43, the outdoor controller (101) increases the opening degree of the second outdoor expansion valve (18) from the current opening degree. Specifically, the outdoor controller (101) further increases the opening degree of the second outdoor expansion valve (18) by 2 pls from the current opening degree. After that, the process proceeds to step ST35. In step ST35, the outdoor controller (101) recalculates the outlet pressure (SP).

Also in this embodiment, it is not necessary to control the first outdoor expansion valve (14) to reduce the two-phase refrigerant pressure (RP) to the target pressure. Therefore, since the intermediate pressure (MP) does not decrease, a sufficient differential pressure between the intermediate pressure (MP) and the second low pressure pressure (LP2) can be secured. Further, it is possible to suppress the imbalance of the compression ratio of the refrigerant between the first compression unit (22, 23) and the second compression unit (21).

<< Embodiment 3 >>
The refrigerating apparatus (1) of the third embodiment is a modification of the refrigerating apparatus (1) of the first embodiment in which the heat source unit (10) and the controller (100) are changed. Here, the refrigerating apparatus (1) of the present embodiment will be described as being different from the refrigerating apparatus (1) of the first embodiment.

<Compression element of heat source unit>
As shown in FIG. 15, the compression element (C) of the present embodiment includes a second bypass pipe (24b) and a third bypass pipe (24c). The second bypass pipe (24b) is a pipe for allowing the refrigerant to flow by bypassing the second compressor (22). One end of the second bypass pipe (24b) is connected to the second suction pipe (22a), and the other end is connected to the second discharge pipe (22b). The third bypass pipe (24c) is a pipe for allowing the refrigerant to flow by bypassing the third compressor (23). One end of the third bypass pipe (24c) is connected to the third suction pipe (23a), and the other end is connected to the third discharge pipe (23b).

The second bypass pipe (24b) is provided with an eighth check valve (CV8). The third bypass pipe (24c) is provided with a ninth check valve (CV9). These check valves (CV8, CV9) allow the flow of the refrigerant in the direction of the arrow shown in FIG. 15 and prohibit the flow of the refrigerant in the direction opposite to the arrow.

<Outdoor circuit of heat source unit>
As shown in FIG. 15, in the refrigerating apparatus (1) of the present embodiment, a connection pipe (83) and an auxiliary valve (19) are provided in the outdoor circuit (11) of the heat source unit (10).

One end of the connection pipe (83) is connected to the part on the second liquid communication pipe (4) side of the second outdoor expansion valve (18) in the outdoor eighth pipe (o8). One end of the connection pipe (83) of the present embodiment is connected to the portion of the outdoor eighth pipe (o8) on the second liquid communication pipe (4) side of the outlet pressure sensor (48). One end of the connection pipe (83) may be connected between the second outdoor expansion valve (18) and the outlet pressure sensor (48) in the outdoor eighth pipe (o8).

The other end of the connection pipe (83) is connected to the low pressure gas pipe (20) of the outdoor circuit (11). The low-pressure gas pipe (20) is a pipe that connects the second suction pipe (22a) to the second gas connecting pipe (5) in the outdoor circuit (11).

The auxiliary valve (19) is provided in the connecting pipe (83). The auxiliary valve (19) is a control valve with a variable opening. The auxiliary valve (19) of the present embodiment is an electronic expansion valve including a pulse motor that drives the valve body.

<controller>
In the controller (100) of the present embodiment, the outdoor controller (101) controls the auxiliary valve (19). Further, the control of the second outdoor expansion valve (18) performed by the outdoor controller (101) of the present embodiment is different from the control performed by the outdoor controller (101) of the first embodiment.

-Control operation of outdoor controller-
The control of the second outdoor expansion valve (18) and the auxiliary valve (19) performed by the outdoor controller (101) will be described.

The outdoor controller (101) uses the second outdoor expansion valve (18) to keep the refrigerant pressure in the cooling circuit (61) of the cooling unit (60) below the refrigerant pressure that the cooling circuit (61) can tolerate. And control the auxiliary valve (19). The refrigerant pressure that the cooling circuit (61) can tolerate is the design pressure Pu of the cooling unit (60). The design pressure Pu of the cooling unit (60) of the present embodiment is 6 MPa (Pu = 6 MPa). The pressure value shown in the description of the control operation of the outdoor controller (101) is merely an example.

Here, when the cooling unit (60) is in the operating state, the measured value of the outlet pressure sensor (48) is slightly higher than the pressure of the refrigerant at the inlet of the cooling circuit (61). This is because the pressure of the refrigerant gradually decreases while flowing through the second liquid connecting pipe (4). On the other hand, in the hydraulic pressure controller (85) of the present embodiment, as described below, the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), is lower than the design pressure Pu of the cooling unit (60). As described above, the opening degrees of the second outdoor expansion valve (18) and the auxiliary valve (19) are controlled. Therefore, when the hydraulic pressure controller (85) controls the second outdoor expansion valve (18) and the auxiliary valve (19), the pressure of the refrigerant flowing into the cooling circuit (61) of the cooling unit (60) is increased. The cooling unit (60) is kept below the design pressure Pu.

<Control of the second outdoor expansion valve>
The operation of the outdoor controller (101) to control the opening degree of the second outdoor expansion valve (18) will be described with reference to the flow chart of FIG. The outdoor controller (101) repeats the control operation shown in the flow chart of FIG. 16 at predetermined time intervals (for example, 30 seconds).

In the process of step ST51, the outdoor controller (101) reads the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), and compares this outlet pressure SP with the first reference pressure PL1. The first reference pressure PL1 is lower than the design pressure Pu of the cooling unit (60) (PL1 <Pu). The first reference pressure PL1 of this embodiment is 4.5 MPa.

In the process of step ST51, when the outlet pressure SP is equal to or less than the first reference pressure PL1 (SP ≦ PL1), the outdoor controller (101) performs the process of step ST52. On the other hand, when the outlet pressure SP exceeds the first reference pressure PL1 (SP> PL1), the outdoor controller (101) performs the process of step ST53.

In the process of step ST52, the outdoor controller (101) opens the second outdoor expansion valve (18) fully. That is, in the process of step ST52, the outdoor controller (101) sets the opening degree of the second outdoor expansion valve (18) to the maximum value.

In the process of step ST53, the outdoor controller (101) compares the outlet pressure SP with the second reference pressure PL2. The second reference pressure PL2 is lower than the design pressure Pu of the cooling unit (60) and higher than the first reference pressure PL1 (PL1 <PL2 <Pu). The second reference pressure PL2 of this embodiment is 5.2 MPa.

In the process of step ST53, when the outlet pressure SP is equal to or higher than the second reference pressure PL2 (PL2 ≤ SP), the outdoor controller (101) performs the process of step ST54. On the other hand, when the outlet pressure SP is lower than the second reference pressure PL2 (SP <PL2), the outdoor controller (101) performs the process of step ST55.

In the process of step ST54, the outdoor controller (101) closes the second outdoor expansion valve (18) fully. That is, in the process of step ST54, the outdoor controller (101) sets the opening degree of the second outdoor expansion valve (18) to substantially zero.

In the process of step ST55, the outdoor controller (101) adjusts the opening degree of the second outdoor expansion valve (18) according to the outlet pressure SP. Specifically, the outdoor controller (101) performs PID control for adjusting the opening degree of the second outdoor expansion valve (18) so that the outlet pressure SP becomes the third reference pressure PL3. The third reference pressure PL3 is higher than the first reference pressure PL1 and lower than the second reference pressure PL2 (PL1 <PL3 <PL2). The third reference pressure PL3 of this embodiment is 4.8 MPa. The outdoor controller (101) may adjust the opening degree of the second outdoor expansion valve (18) by using a control method other than PID control.

As described above, the outdoor controller (101) adjusts the opening degree of the second outdoor expansion valve (18) so that the outlet pressure SP becomes the second reference pressure PL2 or less. As a result, the pressure of the refrigerant supplied from the heat source unit (10) to the operating cooling unit (60) through the second liquid connecting pipe (4) is lower than the design pressure Pu of the cooling unit (60). Is kept in.

<Control of auxiliary valve>
The operation in which the outdoor controller (101) controls the opening degree of the auxiliary valve (19) will be described with reference to FIG.

The outdoor controller (101) reads the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), at predetermined time (for example, 1 second). Then, the outdoor controller (101) sets the opening degree of the auxiliary valve (19) to the opening degree corresponding to the outlet pressure SP.

When the outlet pressure SP is lower than the 4th reference pressure PL4 (SP <PL4), the outdoor controller (101) closes the auxiliary valve (19) fully. In other words, in this case, the outdoor controller (101) sets the opening degree of the auxiliary valve (19) to substantially zero. The fourth reference pressure PL4 is higher than the second reference pressure PL2 and lower than the design pressure Pu (PL2 <PL4 <Pu). The fourth reference pressure PL4 of this embodiment is 5.4 MPa.

When the outlet pressure SP is the fifth reference pressure PL5 or more (PL5 <SP), the outdoor controller (101) opens the auxiliary valve (19) fully. In other words, in this case, the outdoor controller (101) sets the opening degree of the auxiliary valve (19) to the maximum value. The fifth reference pressure PL5 is higher than the fourth reference pressure PL4 and lower than the design pressure Pu (PL4 <PL5 <Pu). The fifth reference pressure PL5 of this embodiment is 5.8 MPa.

When the outlet pressure SP is equal to or higher than the fourth reference pressure PL4 and equal to or lower than the fifth reference pressure PL5 (PL4 ≤ SP ≤ PL5), the outdoor controller (101) makes the opening degree of the auxiliary valve (19) proportional to the outlet pressure SP. Set to the specified value.

Specifically, the outdoor controller (101) sets the opening degree of the auxiliary valve (19) to a value proportional to the difference between the outlet pressure SP and the fourth reference pressure PL4 (SP-PL4). Further, the outdoor controller (101) sets the opening degree of the auxiliary valve (19) to substantially zero when the outlet pressure SP is equal to the fourth reference pressure PL4 (SP = PL4), while the outlet pressure SP is the third. 5 Maximum when equal to the reference pressure PL5 (SP = PL5).

As described above, when the outlet pressure SP is equal to or higher than the second reference pressure PL2 (PL2 ≦ SP), the outdoor controller (101) closes the second outdoor expansion valve (18) fully. On the other hand, the fourth reference pressure PL4 is higher than the second reference pressure PL2 (PL2 <PL4). Therefore, the outdoor controller (101) opens the auxiliary valve (19) when the outlet pressure SP is higher than the second reference pressure PL2 even when the second outdoor expansion valve (18) is closed.

-Refrigerant pressure acting on the second liquid communication pipe and the cooling expansion valve of the cooling unit-
When the cooling unit (60) is in the operating state, the outdoor controller (101) expands the second outdoor so that the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), becomes the second reference pressure PL2 or less. Adjust the opening of the valve (18). Therefore, when the cooling unit (60) is in the operating state, the refrigerant pressure acting on the cooling expansion valve (63) is maintained at a pressure lower than the design pressure Pu of the cooling unit (60).

On the other hand, when the temperature of the air inside the refrigerator falls within the set temperature range, the cooling controller (103) closes the cooling expansion valve (63) and switches the cooling unit (60) from the operating state to the cooling pause state. When the cold expansion valve (63) is closed, the refrigerant pressure of the second liquid connecting pipe (4) rises, and as a result, the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), rises. Then, when the outlet pressure SP rises to the second reference pressure PL2 or higher, the outdoor controller (101) closes the second outdoor expansion valve (18). When a plurality of cooling units (60) are provided in the refrigerating device (1), the outlet pressure SP rises when all the cooling units (60) are in the cooling pause state.

In this way, when the cooling unit (60) is in the cooling pause state, the cooling expansion valve (63) of the cooling unit (60) and the second outdoor expansion valve (18) of the heat source unit (10) are closed. become. In this state, the refrigerant is confined in the portion of the refrigerant circuit (6) between the cold expansion valve (63) and the second outdoor expansion valve (18). Then, when the temperature around the second liquid connecting pipe (4) is relatively high, it is confined in the portion of the refrigerant circuit (6) between the cold expansion valve (63) and the second outdoor expansion valve (18). The pressure of the generated refrigerant rises. Therefore, if no measures are taken, the refrigerant pressure acting on the cooling expansion valve (63) may exceed the design pressure Pu of the cooling unit (60).

On the other hand, in the intermediate unit (80) of the present embodiment, the outdoor controller (101) controls the opening degree of the auxiliary valve (19). Specifically, the outdoor controller (101) opens the auxiliary valve (19) when the outlet pressure SP exceeds the fourth reference pressure PL4. When the auxiliary valve (19) is opened, a part of the refrigerant existing in the second liquid connecting pipe (4) flows out to the low pressure gas pipe (20) through the connecting pipe (83), and as a result, the second liquid is connected. The refrigerant pressure in the liquid communication pipe (4) drops.

As described above, in the refrigerating apparatus (1) of the present embodiment, the refrigerant pressure acting on the cooling expansion valve (63) of the cooling unit (60) even when the cooling unit (60) is in the cooling pause state. However, the pressure is kept lower than the design pressure Pu of the cooling unit (60).

Here, the auxiliary valve (19) opens, in principle, when the cooling unit (60) is in the cooling pause state and the second compressor (22) is stopped. Then, when the auxiliary valve (19) is opened while the first compressor (21) and the third compressor (23) are operating, the refrigerant existing in the second liquid communication pipe (4) is replaced with the first compressor (21). ) Is sucked. Specifically, the refrigerant existing in the second liquid connecting pipe (4) passes through the low pressure gas pipe (20) and the second bypass pipe (24b) in order, and then is discharged from the third compressor (23). It merges with the refrigerant, then passes through the intercooler (17) and is sucked into the first compressor (21).

In addition, the outdoor controller (101) may open the auxiliary valve (19) when all the compressors (21,22,23) are stopped. In that case, the first compressor (21) may be started and the refrigerant existing in the second liquid connecting pipe (4) may be sucked into the first compressor (21). In that case, the refrigerant existing in the second liquid connecting pipe (4) is sucked into the first compressor (21) after being substantially in a gas single-phase state while passing through the intercooler (17).

-Effect of Embodiment 3-
The heat source unit (10) of the present embodiment includes a connecting pipe (83) and an auxiliary valve (19). The connection pipe (83) compresses the downstream portion of the second outdoor expansion valve (18) in the outdoor eighth pipe (o8) provided with the second outdoor expansion valve (18) from the cooling unit (60). Connect to the low pressure gas pipe (20) through which the refrigerant flows toward the element (C). The auxiliary valve (19) is provided in the connecting pipe (83).

Here, when both the cold expansion valve (63) and the second outdoor expansion valve (18) provided in the cold unit (60) are closed, the heat source unit (10) is changed to the cold unit (60). The refrigerant is contained in the second liquid connecting pipe (4) to be connected. If this condition occurs when the temperature around the second liquid connecting pipe (4) is high, the internal pressure of the second liquid connecting pipe (4) rises, and the second liquid connecting pipe (4) and the cooling unit (60) ) May be damaged.

On the other hand, in the heat source unit (10) of the present embodiment, an auxiliary valve (19) is provided in the connecting pipe (83) connecting the outdoor eighth pipe (o8) and the low pressure gas pipe (20). When the auxiliary valve (19) is open, the second liquid communication pipe (4) that connects the heat source unit (10) to the cooling unit (60) is connected to the low-pressure gas pipe (20) via the connection pipe (83). Communicate with. Therefore, the internal pressure of the second liquid communication pipe (4) is in a state where both the cold expansion valve (63) of the cold unit (60) and the second outdoor expansion valve (18) of the heat source unit (10) are closed. As a result, damage to the second liquid connecting pipe (4) and damage to the cooling unit (60) can be avoided.

-Modification Example 1 of Embodiment 3
In the heat source unit (10) of the present embodiment, the auxiliary valve (19) may be an on-off valve that selectively switches between a fully closed state and a fully open state. The auxiliary valve (19) of this modification is a solenoid valve provided with a solenoid that drives the valve body.

As shown in FIG. 18, in the outdoor controller (101) of this modified example, when the auxiliary valve (19) is in the fully closed state, the outlet pressure SP, which is the measured value of the outlet pressure sensor (48), is the fifth reference pressure. When it reaches PL5 (when SP = PL5), the auxiliary valve (19) is switched from the fully closed state to the fully open state. Further, in the outdoor controller (101) of this modification, when the outlet pressure SP reaches the fourth reference pressure PL4 (when SP = PL4) when the auxiliary valve (19) is in the fully open state, the auxiliary valve (19) To switch from the fully open state to the fully closed state. The values of the fourth reference pressure PL4 and the fifth reference pressure PL5 are the same as when the auxiliary valve (19) is a control valve having a variable opening degree.

-Modification example of embodiment 3 2-
In the hydraulic pressure controller (85) of the present embodiment, the fourth reference pressure PL4 may be set to a value slightly lower than the second reference pressure PL2. (PL4 <PL2). Even in that case, the fourth reference pressure PL4 is set to a value higher than the first reference pressure PL1 (PL1 <PL4). In the intermediate unit (80) of this modification, the auxiliary valve (19) may start to open before the second outdoor expansion valve (18) is fully closed.

<< Embodiment 4 >>
The refrigerating apparatus (1) of the present embodiment is a modification of the configuration of the heat source unit (10) of the third embodiment. Here, the difference between the heat source unit (10) of the present embodiment and the heat source unit (10) of the third embodiment will be described.

As shown in FIG. 19, the heat source unit (10) of the present embodiment includes a main heat source unit (10a) and an intermediate unit (80).

The main heat source unit (10a) is the second outdoor expansion valve (18), the outlet pressure sensor (48), the connection pipe (83), and the auxiliary valve (19) from the heat source unit (10) of the third embodiment shown in FIG. ) Is omitted. The main heat source unit (10a) is installed outdoors and is connected to the cooling unit (60) by the second liquid connecting pipe (4) and the second gas connecting pipe (5). The outdoor controller (101) of the present embodiment does not control the second outdoor expansion valve (18) and the auxiliary valve (19).

In the heat source unit (10) of the present embodiment, the second outdoor expansion valve (18), the outlet pressure sensor (48), the connection pipe (83), and the auxiliary valve (19) are provided in the intermediate unit (80). The intermediate unit (80) is a unit formed separately from the main heat source unit (10a). This intermediate unit (80) constitutes an auxiliary unit. Although not shown, the intermediate unit (80) includes a casing that houses its components.

The intermediate unit (80) is connected to the second liquid connecting pipe (4) and the second gas connecting pipe (5). Therefore, in the refrigerant circuit (6) of the present embodiment, the intermediate unit (80) is provided between the main heat source unit (10a) and the cooling unit (60). The intermediate unit (80) is installed indoors.

The intermediate unit (80) further includes a liquid side pipe (81) and a gas side pipe (82). The liquid side pipe (81) is provided in the middle of the second liquid connecting pipe (4). The liquid side pipe (81) is connected to the cooling circuit (61) of the cooling unit (60) and the outdoor eighth pipe (o8) of the outdoor circuit (11) via the second liquid connecting pipe (4). Connecting. This liquid side pipe (81) constitutes the first branch flow path together with the outdoor eighth pipe (o8). The gas side pipe (82) is provided in the middle of the second gas connecting pipe (5). The gas side pipe (82) is connected to the cooling circuit (61) of the cooling unit (60) and the low pressure gas pipe (20) of the outdoor circuit (11) via the second gas connecting pipe (5). To do.

In the heat source unit (10) of the present embodiment, the second outdoor expansion valve (18) and the outlet pressure sensor (48) are provided in the liquid side pipe (81). Similar to the outdoor circuit (11) of the third embodiment, the outlet pressure sensor (48) is arranged closer to the cooling unit (60) than the second outdoor expansion valve (18).

In the heat source unit (10) of the present embodiment, one end of the connection pipe (83) is connected to the liquid side pipe (81) and the other end is connected to the gas side pipe (82). One end of the connection pipe (83) is connected to the portion of the liquid side pipe (81) on the cooling unit (60) side of the second outdoor expansion valve (18). One end of the connection pipe (83) of the present embodiment is connected to the portion of the liquid side pipe (81) on the cooling unit (60) side of the outlet pressure sensor (48). One end of the connection pipe (83) may be connected to the portion of the liquid side pipe (81) between the second outdoor expansion valve (18) and the outlet pressure sensor (48).

In the heat source unit (10) of the present embodiment, the auxiliary valve (19) is provided in the connection pipe (83) in the same manner as the heat source unit (10) of the third embodiment.

The intermediate unit (80) of this embodiment includes a hydraulic controller (85). The hydraulic controller (85), together with the outdoor controller (101), the indoor controller (102), and the cold controller (103), constitutes the controller (100).

As shown in FIG. 20, the hydraulic controller (85) includes a microcomputer mounted on a control board and a memory device (specifically, a semiconductor memory) for storing software for operating the microcomputer. including. The hydraulic pressure controller (85) is electrically connected to the second outdoor expansion valve (18), the auxiliary valve (19), and the outlet pressure sensor (48) via a communication line.

The hydraulic pressure controller (85) controls the second outdoor expansion valve (18) and the auxiliary valve (19) based on the outlet pressure SP, which is the measured value of the outlet pressure sensor (48). The control of the second outdoor expansion valve (18) and the auxiliary valve (19) performed by the hydraulic controller (85) is performed by the outdoor controller (101) of the third embodiment of the second outdoor expansion valve (18) and the auxiliary valve (19). ) Is the same as the control.

-Features of Embodiment 4-
The intermediate unit (80) of this embodiment is arranged indoors. Therefore, in the summer when the outside air temperature is high, the ambient temperature of the part between the intermediate unit (80) and the cooling unit (60) of the liquid communication pipe (4) is lower than that of the outdoors. Therefore, in a state where both the cold expansion valve (63) of the cold unit (60) and the second outdoor expansion valve (18) of the intermediate unit (80) are closed, the intermediate unit (of the liquid communication pipe (4)) ( The rise in internal pressure in the part between 80) and the cooling unit (60) is suppressed.

Also, the intermediate unit (80) may be placed in the same indoor space as the cooling unit (60). Normally, the cooling unit (60) is installed in an indoor space where air conditioning is performed by the air conditioning unit (50). For example, even when the outside air temperature becomes relatively high in summer, the air temperature in the indoor space where the intermediate unit (80) and the cooling unit (60) are installed is lower than the outdoor air temperature. Therefore, if the intermediate unit (80) is installed indoors, both the cold expansion valve (63) of the cold unit (60) and the second outdoor expansion valve (18) of the intermediate unit (80) are closed. , The increase in internal pressure in the part of the liquid communication pipe (4) between the intermediate unit (80) and the cooling unit (60) is suppressed.

-Modification Example 1 of Embodiment 4
The intermediate unit (80) of the above embodiment may include a pressure input unit (86). The pressure input unit (86) is a member operated by the operator to input information regarding the design pressure Pu of the cooling unit (60). Examples of the pressure input unit (86) include a DIP switch and a numeric keypad for inputting numbers.

As shown in FIG. 21, in the intermediate unit (80) of this modification, the pressure input unit (86) is electrically connected to the hydraulic controller (85) via a communication line or the like. The information input to the pressure input unit (86) is transmitted to the hydraulic pressure controller (85) and recorded in the memory device of the hydraulic pressure controller (85). The information input to the pressure input unit (86) may be the value of the design pressure Pu of the cooling unit (60), or may be a symbol such as a number corresponding to the design pressure Pu.

The hydraulic controller (85) of this modification sets the reference pressures PL1 to PL5 based on the information input to the pressure input unit (86), and uses the set reference pressures PL1 to PL5 to set the second outdoor expansion valve. Control the opening degree of (18) and auxiliary valve (19).

-Modification example of embodiment 4 2-
In the intermediate unit (80) of the above embodiment, the hydraulic pressure controller (85) may be omitted. In that case, the outdoor controller (101) of the heat source unit (10) controls the opening degrees of the second outdoor expansion valve (18) and the auxiliary valve (19) based on the measured values of the outlet pressure sensor (48). .. In that case, the control operation performed by the heat source unit (10) is the same as the control operation performed by the hydraulic controller (85) of the above embodiment.

<< Other Embodiments >>
In the above embodiment, the configuration may be as follows.

In the heat source units (10) of the first and second embodiments, the second decompression mechanism (18) may be a mechanism that does not adjust the opening degree. In this case, the second decompression mechanism (18) may be a capillary tube.

In the heat source units (10) of the first to fourth embodiments, the number of cooling units (60) is not limited to one. It may be a refrigerating device (1) in which a plurality of cooling units (60, 60, ...) Are connected in parallel.

The number of air conditioning units (50) is not limited to one in the heat source units (10) of the first to fourth embodiments. It may be a refrigerating device (1) in which a plurality of cooling units (50, 50, ...) Are connected in parallel.

In the heat source units (10) of the first to fourth embodiments, the cold heat exchanger (64) does not have to be an air heat exchanger that exchanges heat between air and the refrigerant. The cold heat exchanger (64) may be, for example, a cooling heat exchanger that cools water or brine with a refrigerant.

In the heat source units (10) of the first to fourth embodiments, the indoor heat exchanger (54) does not have to be an air heat exchanger that exchanges heat between air and the refrigerant. The indoor heat exchanger (54) may be, for example, a heat heat exchanger that heats water or brine with a refrigerant.

Although the embodiments and modifications have been described above, it will be understood that various modifications of the forms and details are possible without deviating from the purpose and scope of the claims. Further, the above embodiments and modifications may be appropriately combined or replaced as long as the functions of the subject of the present disclosure are not impaired. The descriptions "1st", "2nd", "3rd" ... described above are used to distinguish the words and phrases to which these descriptions are given, and the number and order of the words and phrases are also limited. It's not something to do.

As described above, the present disclosure is useful for heat source units and refrigeration equipment.

C Compression element M Main flow path o6 Outdoor 6th pipe (2nd branch flow path)
o8 Outdoor 8th pipe (1st branch flow path)
1 Refrigerant 6 Refrigerant circuit 11 Heat source circuit 13 Outdoor heat exchanger (heat exchanger)
14 1st outdoor expansion valve (1st decompression mechanism)
15 Gas-liquid separator 16 Supercooling heat exchanger (cooling heat exchanger)
16a 1st flow path 16b 2nd flow path 18 2nd outdoor expansion valve (second pressure reducing mechanism)
19 Auxiliary valve 20 Low pressure gas pipe 21 1st compressor (2nd compression part)
22 Second compressor (first compression unit)
23 Third compressor (first compression unit)
37 Degassing pipe (first pipe)
38 Injection pipe 48 Outlet pressure sensor (pressure acquisition unit)
49 Intermediate injection circuit 50 Air conditioning unit (second use unit)
60 Refrigeration unit (first utilization unit)
80 Intermediate unit (auxiliary unit)
81 Liquid side piping (first branch flow path)
83 Connection piping 101 Outdoor controller (control unit)

Claims

In the utilization circuit (51, 61) of the utilization unit (50, 60) having the first utilization unit (60) and the second utilization unit (50) having a higher refrigerant evaporation temperature than the first utilization unit (60). A heat source unit including a heat source circuit (11) that is connected to form a refrigerant circuit (6) that performs a refrigeration cycle, and a control unit (100) that controls the heat source circuit (11).
The heat source circuit (11)
A compression element (C) having a first compression unit (22, 23) and a second compression unit (21) that further compresses the refrigerant compressed by the first compression unit (22, 23).
With the radiator (13),
The first decompression mechanism (14) and
A main flow path (M) connected to the downstream side of the radiator (13) and provided with the first decompression mechanism (14),
A first branch flow path (o8) connected to the end of the main flow path (M) and communicating with the first utilization unit (60).
A second branch flow path (o6) connected to the end of the main flow path (M) and communicating with the second utilization unit (50).
One end is connected to the main flow path (M), the other end is connected between the first compression section (22, 23) and the second compression section (21), and the pressure is reduced by the first decompression mechanism (14). An intermediate injection circuit (49) into which the compressed refrigerant flows in, and
A heat source unit including a second decompression mechanism (18) provided in the first branch flow path (o8).
In claim 1,
The heat source circuit (11) includes a gas-liquid separator (15).
The intermediate injection circuit (49) includes a first refrigerant pipe (37) connected to the gas-liquid separator (15).
In the first refrigerant pipe (37), the gas refrigerant in the gas-liquid separator (15) is transferred from the gas-liquid separator (15) to the first compression section (22, 23) and the second compression section (the second compression section (15). A heat source unit characterized in that it is configured to flow into a flow path between and 21).
In claim 1 or 2,
The heat source circuit (11) includes a pressure acquisition unit (48) that detects or estimates the pressure of the refrigerant after decompression by the second decompression mechanism (18).
The second decompression mechanism (18) is a valve whose opening degree can be adjusted.
The heat source is characterized in that the control unit (100) controls the opening degree of the second decompression mechanism (18) so that the pressure detected or estimated by the pressure acquisition unit (48) becomes the target pressure. unit.
In any one of claims 1 to 3,
The heat source circuit (11) includes a cooling heat exchanger (16) connected between the first decompression mechanism (14) and the second decompression mechanism (18).
The cooling heat exchanger (16)
The first flow path (16a) connected to the liquid pipe through which the liquid refrigerant of the heat source circuit (11) flows, and
It has a second flow path (16b) through which the decompressed refrigerant flows, which is separated from the liquid pipe.
The refrigerant in the second flow path (16b) is configured to cool the refrigerant in the first flow path (16a).
The second flow path (16b) is a heat source unit comprising the intermediate injection circuit (49).
In claim 4,
The control unit (100) is a heat source unit characterized in that the cooling capacity of the cooling heat exchanger (16) is controlled so that the refrigerant flowing out of the second decompression mechanism (18) is in a liquid state.
In any one of claims 1 to 5,
The first utilization unit (60) is a cooling unit that cools the inside of the refrigerating equipment.
The second utilization unit (50) is a heat source unit characterized by being an air conditioning unit that air-conditions a room.
In any one of claims 1 to 6,
The control unit (100) compresses the refrigerant to a critical pressure or higher by the compression element (C), and performs a refrigeration cycle in which the refrigerant is depressurized to a subcritical pressure by the first decompression mechanism (14). ) Is a heat source unit.
In any one of claims 1 to 7,
A heat source unit characterized in that the refrigerant is carbon dioxide.
In any one of claims 1 to 8,
A low-pressure gas pipe (a low-pressure gas pipe in which a refrigerant flows from the utilization unit (50, 60) toward the compression element (C) through a portion of the first branch flow path (o8) on the downstream side of the second decompression mechanism (18). Connection pipe (83) to connect to 20) and
A heat source unit including an auxiliary valve (19) provided in the connection pipe (83).
In any one of claims 1 to 9,
The heat source unit (10) includes a main heat source unit (10a) and an auxiliary unit (10b, 80) separated from the main heat source unit (10a), and the auxiliary unit (10b, 80) is the second decompression. A heat source unit characterized by having a mechanism (18).
With any one of the heat source units (10) of claims 1 to 10,
A utilization unit (50, 60) having a utilization circuit (51, 61) including a first utilization unit (60) and a second utilization unit (50) having a higher evaporation temperature of the refrigerant than the first utilization unit (60). With and
The heat source circuit (11) of the heat source unit (10) and the utilization circuit (51, 61) of the utilization unit (50, 60) are connected to form a refrigerant circuit (6) that performs a refrigeration cycle. A freezing device characterized by.