JP2012052801A - Refrigerating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent power recovered with an expander from being lost by a regulating valve for regulation of the flow rate of a refrigerant when a heat exchanger changes into an evaporator until the refrigerant radiated with the heat exchanger flows into the expander, in a freezer in which the expander for recovery of power is provided in a refrigerant circuit.SOLUTION: The refrigerant circuit (10) is provided with a switching circuit (24) for switching a state where an expansion inflow line (48) communicates with a line (38) on the heat source side and besides an expansion outflow line (49) communicates with a line (39) on the use side and a state where the expansion inflow line (48) communicates with a line (39) on the use side and besides the expansion outflow line (49) communicates with the line (38) on the heat source side. Then, an regulating valve (43) on the heat source side, which regulates the flow rate of the refrigerant of the heat exchanger (44) on the heat source side at heating operation is provided in a flow passage (52) for the refrigerant which connects the expansion outflow line (49) with the line (38) on the heat source side in a switching circuit (24).

Description

  The present invention relates to a refrigeration apparatus in which an expander for power recovery is provided in a refrigerant circuit.

  Conventionally, a refrigerating apparatus in which an expander for power recovery is provided in a refrigerant circuit is known. In this type of refrigeration apparatus, for example, a compressor and an expander are connected by a single drive shaft, and the power recovered by the expander is used to drive the compressor.

  FIG. 7 of Patent Document 1 discloses an air conditioner as this type of refrigeration apparatus. The air conditioner is configured such that the refrigerant radiated by the outdoor heat exchanger flows into the expander during the cooling operation, and the power accompanying the expansion of the refrigerant is recovered in the expander. Further, during the heating operation, the refrigerant radiated by the indoor heat exchanger flows into the expander, and the motive power accompanying the expansion of the refrigerant is recovered in the expander.

JP 2006-308207 A

  By the way, in the conventional refrigeration apparatus, a control valve is provided between the bridge circuit and the heat source side heat exchanger so that the refrigerant flow rate of the evaporator can be adjusted during the heating operation. However, during the cooling operation, the refrigerant radiated by the heat source side heat exchanger passes through the control valve before flowing into the expander. In the expansion valve, the pressure loss of the refrigerant becomes larger than that of the pipe even if the opening degree is set to be fully open. For this reason, there is a problem that the power recovered in the expander is lost by the control valve.

  The present invention has been made in view of such a point, and the purpose of the roller is that in the refrigeration apparatus in which the expander for power recovery is provided in the refrigerant circuit, the refrigerant radiated by the heat exchanger is transferred to the expander. The purpose is to prevent the power recovered by the expander from being lost by the control valve for adjusting the flow rate of the refrigerant when the heat exchanger becomes an evaporator until the heat exchanger flows.

  In the first invention, a compressor (30), an expander (31), a heat source side heat exchanger (44), and a use side heat exchanger (41) are connected to perform a refrigeration cycle by circulating a refrigerant. A cooling circuit comprising a refrigerant circuit (10), wherein the heat source side heat exchanger (44) serves as a radiator and the use side heat exchanger (41) serves as an evaporator, and the use side heat exchanger (41) A refrigeration apparatus (20) capable of selecting a heating operation in which the heat source side heat exchanger (44) becomes an evaporator becomes a target.

  In the refrigeration apparatus (20), the refrigerant circuit (10) has one end connected to the liquid side of the heat source side heat exchanger (44) and one end connected to the use side. The utilization side line (39) connected to the liquid side of the heat exchanger (41), the expansion inlet line (48) whose outlet end is connected to the inlet side of the expander (31), and the inlet end of the expander ( 31) and an expansion / outflow line (49) connected to the outflow side of the refrigerant circuit (10), the expansion / inflow line (48) communicates with the heat source side line (38) and the refrigerant circuit (10) The expansion / outflow line (49) communicates with the use side line (39), the expansion / inflow line (48) communicates with the use side line (39), and the expansion / outflow line (49) communicates with the heat source side line. (38) is provided with a switching circuit (24) for switching between the state in communication with the state and the heat source in the switching circuit (24). A refrigerant flow passage (52) connecting the line (38) and the expansion / outflow line (49) has a heat source side control valve (adjusting the refrigerant flow rate of the heat source side heat exchanger (44) during the heating operation). 43) is provided.

  In 1st invention, the refrigerant | coolant thermally radiated with the utilization side heat exchanger (41) at the time of a heating operation connects an expansion outflow line (49) and a heat source side line (38) after passing an expander (31). It flows into the heat source side heat exchanger (44) serving as an evaporator through the refrigerant flow passage (52). The refrigerant flow rate of the heat source side heat exchanger (44) is adjusted by the heat source side adjustment valve (43) when passing through the refrigerant flow passage (52). On the other hand, during the cooling operation, the refrigerant dissipated in the heat source side heat exchanger (44) passes through the refrigerant flow path connecting the heat source side line (38) and the expansion inflow line (48) to the expander (31). Flow into. The refrigerant radiated by the heat source side heat exchanger (44) flows into the expander (31) without passing through the heat source side control valve (43).

  In the second invention, the compressor (30), the expander (31), the heat source side heat exchanger (44), and the use side heat exchanger (41) are connected, and the refrigerant is circulated to perform the refrigeration cycle. A cooling circuit comprising a refrigerant circuit (10), wherein the heat source side heat exchanger (44) serves as a radiator and the use side heat exchanger (41) serves as an evaporator, and the use side heat exchanger (41) A refrigeration apparatus (20) capable of selecting a heating operation in which the heat source side heat exchanger (44) becomes an evaporator becomes a target.

  In the refrigeration apparatus (20), the refrigerant circuit (10) has one end connected to the liquid side of the heat source side heat exchanger (44) and one end connected to the use side. The utilization side line (39) connected to the liquid side of the heat exchanger (41), the expansion inlet line (48) whose outlet end is connected to the inlet side of the expander (31), and the inlet end of the expander ( 31) and an expansion / outflow line (49) connected to the outflow side of the refrigerant circuit (10), the expansion / inflow line (48) communicates with the heat source side line (38) and the refrigerant circuit (10) The expansion / outflow line (49) communicates with the use side line (39), the expansion / inflow line (48) communicates with the use side line (39), and the expansion / outflow line (49) communicates with the heat source side line. (38) is provided with a switching circuit (24) for switching between the state in communication with the switching circuit (24). A refrigerant flow passageway (61) connecting the line (39) and the expansion / outflow line (49) has a utilization side control valve (adjusting the refrigerant flow rate of the utilization side heat exchanger (41) during the cooling operation). 53).

  In 2nd invention, the refrigerant | coolant which thermally radiated with the heat source side heat exchanger (44) at the time of cooling operation connects an expansion outflow line (49) and a utilization side line (39) after passing an expander (31). The refrigerant flows through the refrigerant flow passage (61) and flows into the use side heat exchanger (41) serving as an evaporator. The refrigerant flow rate of the use side heat exchanger (41) is adjusted by the use side adjustment valve (53) when passing through the refrigerant flow passageway (61). On the other hand, during the heating operation, the refrigerant radiated by the use side heat exchanger (41) passes through the refrigerant flow passage connecting the use side line (39) and the expansion inflow line (48) to the expander (31). Flow into. The refrigerant radiated by the use side heat exchanger (41) flows into the expander (31) without passing through the use side control valve (53).

  In a third aspect based on the first aspect, in the switching circuit (24), the refrigerant flow passage (52) provided with the heat source side control valve (43) is connected to the heat source side line (38). A check valve (CV-4) that prohibits the flow of refrigerant toward the expansion / outflow line (49) is provided.

  In the third aspect of the invention, a check valve (CV-4) is provided in addition to the heat source side control valve (43) in the refrigerant flow passage (52) provided with the heat source side control valve (43). The check valve (CV-4) prohibits the flow of refrigerant from the heat source side line (38) toward the expansion / outflow line (49). That is, the refrigerant is prohibited from flowing through the refrigerant flow passage (52) during the cooling operation.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, in order to adjust a refrigerant flow rate that bypasses the expander (31) during the cooling operation, a bypass amount that adjusts an opening degree of the heat source side control valve (43). Adjusting means (65) is provided.

  In the fourth invention, the opening degree of the heat source side adjustment valve (43) is adjusted by the bypass amount adjustment means (65) during the cooling operation. When the heat source side control valve (43) is set to the open state, a part of the refrigerant that has passed through the heat source side line (38) connects the expansion / outflow line (49) and the heat source side line (38). Into the flow passage (52), and merges with the refrigerant that has passed through the expansion / outflow line (49) and travels toward the use-side heat exchanger (41). That is, the refrigerant that has passed through the heat source side line (38) bypasses the expander (31) and travels to the use side heat exchanger (41). In the fourth aspect of the invention, the refrigerant flow rate that bypasses the expander (31) during the cooling operation is adjusted by the bypass amount adjusting means (65).

  In a fifth aspect based on any one of the first to fourth aspects, the expansion / outflow line (49) is provided with a refrigerant storage tank (35) capable of temporarily storing the refrigerant.

  In the fifth invention, the refrigerant expanded by the expander (31) passes through the refrigerant storage tank (35) and then flows into the heat source side adjustment valve (43) or the use side adjustment valve (53). For this reason, whether the amount of refrigerant flowing out of the expander (31) is large or small with respect to the opening of the heat source side control valve (43) or the use side control valve (53), the heat source The refrigerant flow rate that passes through the side adjustment valve (43) or the use side adjustment valve (53) is adjusted to a flow rate according to the opening by the refrigerant storage tank (35).

  According to a sixth invention, in any one of the first to fifth inventions, a bypass line connecting the expansion inflow line (48) and the expansion outflow line (49) to the refrigerant circuit (10). (28) and a bypass amount adjusting valve (29) for adjusting the refrigerant flow rate in the bypass line (28) are provided.

  In the sixth invention, by setting the bypass amount adjusting valve (29) to the open state during the cooling operation, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31). Then flows into the expansion / outflow line (49). On the other hand, even during the heating operation, by setting the bypass amount adjusting valve (29) to the open state, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31) and the expansion outflow line. Flows into (49). In the sixth aspect of the invention, the flow rate of the refrigerant that bypasses the expander (31) is adjusted by the bypass line (28) and the bypass amount adjustment valve (29) in both the cooling operation and the heating operation.

  According to a seventh invention, in any one of the first to sixth inventions, the refrigerant circuit (10) has a heat source side circuit (14) provided with the heat source side heat exchanger (44). A plurality of use side circuits (11) each provided with the use side heat exchanger (41) are connected in parallel to each other.

  In the seventh invention, the plurality of use side circuits (11) are connected in parallel to the heat source side circuit (14). In the refrigerant circuit (10), the refrigerant flowing out from the heat source side circuit (14) merges after passing through each use side circuit (11) and returns to the heat source side circuit (14).

  In an eighth invention according to any one of the first to seventh inventions, in the refrigerant circuit (10), the refrigerant is circulated so that the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

  In the eighth invention, the high pressure of the refrigeration cycle performed in the refrigerant circuit (10) is set to a value higher than the critical pressure of the refrigerant. That is, the refrigerant discharged from the compressor (30) is in a supercritical state.

  In each of the first, third to eighth inventions, by providing the heat source side control valve (43) in the refrigerant flow passage (52) connecting the heat source side line (38) and the expansion / outflow line (49), The refrigerant radiated by the heat source side heat exchanger (44) during the cooling operation flows into the expander (31) without passing through the heat source side control valve (43). That is, the heat source side control valve (43) is disposed at a position other than the refrigerant flow path between the heat source side heat exchanger (44) and the expander (31) during the cooling operation. Therefore, the power recovered by the expander (31) during the cooling operation is not lost due to the heat source side control valve (43) that adjusts the refrigerant flow rate of the heat source side heat exchanger (44) during the heating operation. Further, it is possible to prevent the operating efficiency of the refrigeration apparatus (20) from being lowered by the heat source side control valve (43).

  In each of the second, fifth to eighth inventions, the use-side control valve (53) is provided in the refrigerant flow passage (61) connecting the expansion / outflow line (49) and the use-side line (39). Thus, the refrigerant radiated by the use side heat exchanger (41) during the heating operation flows into the expander (31) without passing through the use side control valve (53). That is, the use side control valve (53) is disposed at a position other than the refrigerant flow path between the use side heat exchanger (41) and the expander (31) during the heating operation. Therefore, the power recovered by the expander (31) during the heating operation is not lost due to the use-side control valve (53) that adjusts the refrigerant flow rate of the usage-side heat exchanger (41) during the cooling operation. Thus, it is possible to prevent the operating efficiency of the refrigeration apparatus (20) from being lowered by the use side control valve (53).

  In the third aspect of the invention, the check valve (CV-4) is provided in the refrigerant flow passage (52) connecting the heat source side line (38) and the expansion / outflow line (49), so that the cooling operation can be performed. The refrigerant is prohibited from flowing through the refrigerant flow path (52). Here, when a check valve (CV-4) is not provided in the refrigerant flow passage (52), the heat source side adjustment is performed so that the refrigerant does not flow through the refrigerant flow passage (52) during the cooling operation. Even when the valve (43) is set to the fully closed state, the refrigerant may leak from the heat source side control valve (43). The refrigerant leaking from the heat source side control valve (43) joins with the refrigerant that has passed through the expansion / outflow line (49) and travels toward the use side heat exchanger (41). That is, a part of the refrigerant passing through the heat source side line (38) unintentionally bypasses the expander (31), and the power recovered by the expander (31) decreases. In contrast, in the third aspect of the invention, the check valve (CV-4) can prevent the refrigerant from leaking from the heat source side adjustment valve (43) during the cooling operation. Therefore, it is possible to prevent the power recovered by the expander (31) from being reduced unintentionally.

  In the fourth aspect of the invention, the refrigerant flow rate that bypasses the expander (31) during the cooling operation is adjusted by the bypass amount adjusting means (65). Here, for example, when the compressor (30) and the expander (31) are connected by a single drive shaft, the expander (31) with respect to the refrigerant flow rate discharged by the compressor (30). In some cases, it is difficult to perform a desired refrigeration cycle because the refrigerant flow rate of the refrigerant is not balanced. In order to solve such a problem, it is conceivable to provide a pipe for bypassing the expander (31) in the refrigerant circuit (10). However, the configuration of the refrigerant circuit (10) is complicated accordingly. On the other hand, in the fourth aspect of the invention, the refrigerant flow passage (52) connecting the heat source side line (38) and the expansion / outflow line (49) is used as a flow path for bypassing the expander (31). ing. Therefore, the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) can be balanced without complicating the configuration of the refrigerant circuit (10).

  In the sixth aspect of the invention, the refrigerant flow rate for bypassing the expander (31) is adjusted by the bypass line (28) and the bypass amount adjusting valve (29) in both the cooling operation and the heating operation. ing. Accordingly, it is possible to balance the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) in both the cooling operation and the heating operation.

It is a schematic block diagram of the air conditioning machine which concerns on embodiment. It is a schematic block diagram of the air conditioning machine which concerns on the modification of embodiment. It is a schematic block diagram of the air conditioning machine which concerns on the 1st modification of other embodiment. It is a schematic block diagram of the bridge circuit which concerns on the 3rd modification of other embodiment. It is a schematic block diagram of the bridge circuit which concerns on the 4th modification of other embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The present embodiment is an air conditioner (20) configured by a refrigeration apparatus according to the present invention. As shown in FIG. 1, the air conditioner (20) includes one outdoor unit (64) and three indoor units (63a, 63b, 63c). The number of indoor units (63) is merely an example. The air conditioner (20) is configured to be able to select a cooling operation that is a cooling operation and a heating operation that is a heating operation.

The air conditioner (20) of the present embodiment includes a refrigerant circuit (10) filled with carbon dioxide (CO ₂ ) as a refrigerant. In the refrigerant circuit (10), a refrigerant (CO ₂ ) is circulated to perform a vapor compression refrigeration cycle. In this refrigeration cycle, the high pressure of the refrigeration cycle is set to a value higher than the critical pressure of carbon dioxide.

  The refrigerant circuit (10) includes three indoor circuits (11a, 11b, 11c) that are use side circuits and one outdoor circuit (14) that is a heat source side circuit. These indoor circuits (11a, 11b, 11c) are connected in parallel to the outdoor circuit (14) by the first connecting pipe (15) and the second connecting pipe (16). Specifically, one end of the first communication pipe (15) is connected to the first shut-off valve (17) of the outdoor circuit (14), and the other end is branched into three to each indoor circuit (11a, 11b, 11c). ) Connected to the liquid side end. One end of the second communication pipe (16) is connected to the second shut-off valve (18) of the outdoor circuit (14), and the other end branches into three, and the gas side of each indoor circuit (11a, 11b, 11c) Connected to the end.

《Outdoor circuit configuration》
The outdoor circuit (14) is accommodated in the outdoor unit (64). The outdoor circuit (14) includes a compression / expansion unit (26), an outdoor heat exchanger (44), a refrigerant storage tank (35), an internal heat exchanger (45), a four-way switching valve (25), and a bridge circuit. (24) is provided. The bridge circuit (24) constitutes a switching circuit. The outdoor unit (64) is provided with an outdoor fan (not shown) for sending outdoor air to the outdoor heat exchanger (44).

  The compression / expansion unit (26) includes a casing (21) which is a vertically long and cylindrical sealed container. A compressor (30), an expander (31), and an electric motor (32) are accommodated in the casing (21). In the casing (21), the compressor (30), the electric motor (32), and the expander (31) are connected to each other by a single drive shaft.

Each of the compressor (30) and the expander (31) is constituted by a positive displacement fluid machine (such as a swinging piston type rotary fluid machine, a rolling piston type rotary fluid machine, and a scroll fluid machine). The compressor (30) compresses the sucked refrigerant (CO ₂ ) to the critical pressure or higher. The expander (31) expands the inflowing refrigerant (CO ₂ ) to recover power (expansion power). The compressor (30) is driven by both the power recovered by the expander (31) and the power obtained by energizing the electric motor (32). AC power is supplied to the electric motor (32) from an inverter not shown. The compressor (30) is configured to have a variable capacity by changing the frequency of the alternating current supplied to the electric motor (32). The compressor (30) and the expander (31) always rotate at the same rotational speed.

  The outlet end of the expansion inflow line (48) is connected to the inflow side of the expander (31). The inlet end of the expansion inflow line (48) is connected to the bridge circuit (24). The inlet end of the expansion / outflow line (49) is connected to the outflow side of the expander (31). The outlet end of the expansion / outflow line (49) is connected to the bridge circuit (24).

  The outdoor heat exchanger (44), which is a heat source side heat exchanger, is configured by a cross fin type fin-and-tube heat exchanger. Outdoor air is supplied to the outdoor heat exchanger (44) by an outdoor fan. In the outdoor heat exchanger (44), heat is exchanged between the outdoor air and the refrigerant. The gas side of the outdoor heat exchanger (44) is connected to the third port of the four-way switching valve (25). One end of a heat source side line (38) is connected to the liquid side of the outdoor heat exchanger (44). The other end of the heat source side line (38) is connected to the bridge circuit (24).

  The refrigerant storage tank (35) is a vertically long and cylindrical sealed container. The refrigerant storage tank (35) is provided in the expansion / outflow line (49). In the refrigerant storage tank (35), the refrigerant pipe extending from the expander (31) is connected to an upper position of the refrigerant storage tank (35). A refrigerant pipe extending to the bridge circuit (24) is connected to the bottom of the refrigerant storage tank (35). A gas supply pipe (37) connected to the suction side of the compressor (30) is connected to the top of the refrigerant storage tank (35). The gas supply pipe (37) is provided with a gas amount adjusting valve (36) constituted by an electronic expansion valve having a variable opening.

  In the refrigerant storage tank (35), the refrigerant flowing from the expander (31) is separated into liquid refrigerant and gas refrigerant. Among them, the liquid refrigerant flows into the bridge circuit (24) from the bottom of the refrigerant storage tank (35). The gas refrigerant flows out of the gas supply pipe (37) and is sucked into the compressor (30). In the refrigerant storage tank (35), the refrigerant from the expander (31) toward the bridge circuit (24) is temporarily stored.

  The internal heat exchanger (45) is provided across the gas supply pipe (37) and the expansion / outflow line (49). The internal heat exchanger (45) includes a first channel (46) installed downstream of the refrigerant storage tank (35) in the expansion / outflow line (49), and a first channel installed in the middle of the gas supply pipe (37). And two flow paths (47). In the internal heat exchanger (45), the first channel (46) and the second channel (47) are arranged adjacent to each other. In the internal heat exchanger (45), heat exchange is performed between the refrigerant in the first flow path (46) and the refrigerant in the second flow path (47).

  The bridge circuit (24) is a circuit in which the first connection line (51), the second connection line (52), the third connection line (61), and the fourth connection line (62) are connected in a bridge shape. The first connection line (51) connects the other end of the heat source side line (38) and the inlet end of the expansion inflow line (48). The second connection line (52) connects the other end of the heat source side line (38) and the outlet end of the expansion / outflow line (49). The third connection line (61) connects the other end of the use side line (39) and the outlet end of the expansion / outflow line (49). The fourth connection line (62) connects the other end of the use side line (39) and the inlet end of the expansion inflow line (48).

  In addition, in this embodiment, from the connection location of the 3rd connection line (61) and the 4th connection line (62) in a bridge circuit (24) to the indoor heat exchanger (41a, 41b, 41c) mentioned later Refrigerant piping constitutes the use side line (39). Specifically, the use side line (39) includes a refrigerant pipe between the bridge circuit (24) and the first closing valve (17), a first communication pipe (15), and each indoor circuit (11a, 11b, 11c). ) And a refrigerant pipe between the indoor heat exchanger (41a, 41b, 41c).

  The first connection line (51) is provided with a first check valve (CV-1) that prohibits the flow of refrigerant from the inlet end of the expansion inflow line (48) toward the other end of the heat source side line (38). ing. The second connection line (52) is provided with an outdoor control valve (43) that constitutes a heat source side control valve. The third connection line (61) is provided with a second check valve (CV-2) that prohibits the flow of refrigerant from the other end of the use side line (39) toward the outlet end of the expansion / outflow line (49). ing. The fourth connection line (62) is provided with a third check valve (CV-3) that prohibits the flow of refrigerant from the inlet end of the expansion inflow line (48) toward the other end of the use side line (39). ing.

  In the bridge circuit (24), the refrigerant that has passed through the outdoor heat exchanger (44) during the cooling operation is the heat source side line (38), the first connection line (51), the expansion inflow line (48), the expander (31), A cooling flow path is formed to flow in the order of the expansion / outflow line (49), the third connection line (61), and the use side line (39). Further, the bridge circuit (24) allows the refrigerant that has passed through each indoor heat exchanger (41) during heating operation to be used side line (39), fourth connection line (62), expansion inflow line (48), expander. (31), an expansion / outflow line (49), a second connection line (52), and a heat source side line (38) are formed in this order to form a heating flow path.

  The first port of the four-way switching valve (25) is connected to the suction side of the compressor (30). The second port is connected to the second closing valve (18). The third port is connected to the outdoor heat exchanger (44). The fourth port is connected to the discharge side of the compressor (30). The four-way selector valve (25) has a state in which the first port and the second port communicate with each other and the third port and the fourth port communicate with each other (a first state indicated by a solid line in FIG. 1); A state in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other (second state indicated by a broken line in FIG. 1) is configured to be switchable.

  In the outdoor circuit (14), a discharge temperature sensor (22) and a discharge pressure sensor (19) are provided on the discharge side of the compressor (30). A suction temperature sensor (23) and a suction pressure sensor (27) are provided on the suction side of the compressor (30).

《Indoor circuit configuration》
Each indoor circuit (11a, 11b, 11c) is accommodated in each indoor unit (63a, 63b, 63c). Each indoor circuit (11) has an indoor heat exchanger (41a, 41b, 41c) that is a use side heat exchanger and an indoor adjustment that is a use side control valve in order from the gas side end to the liquid side end. Valves (53a, 53b, 53c) are provided. Each indoor unit (63) is provided with an indoor fan for sending room air to each indoor heat exchanger (41) (not shown).

  The indoor heat exchanger (41) is configured by a cross fin type fin-and-tube heat exchanger. Indoor air is supplied to the indoor heat exchanger (41) by an indoor fan. In the indoor heat exchanger (41), heat is exchanged between the indoor air and the refrigerant. The indoor control valve (53) is an electronic expansion valve with a variable opening.

  In each indoor circuit (11), indoor liquid temperature sensors (12a, 12b, 12c) are provided on the liquid side of the indoor heat exchanger (41). Indoor gas temperature sensors (13a, 13b, 13c) are provided on the gas side of the indoor heat exchanger (41).

-Driving action-
The operation of the air conditioner (20) will be described. The air conditioner (20) is provided with a controller (65) for switching the four-way switching valve (33) and controlling the operation state.

《Cooling operation》
In the cooling operation, the controller (65) sets the four-way switching valve (25) to the first state shown by the solid line in FIG. In this state, when the controller (65) operates the compressor (30), the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, the outdoor heat exchanger (44) functions as a radiator, and each indoor heat exchanger (41) functions as an evaporator.

  The controller (65) during the cooling operation keeps the opening degree of the outdoor control valve (43) in a fully closed state. During the cooling operation, the opening degree of each indoor control valve (53) is adjusted based on the measured value of the indoor liquid temperature sensor (12) and the measured value of the indoor gas temperature sensor (13). Refrigerant flow rate of the indoor heat exchanger (41) so that the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger (41) becomes a target value (for example, 5 ° C) by adjusting the opening of the indoor control valve (53). Is adjusted.

  Specifically, the refrigerant having a pressure higher than the critical pressure is discharged from the compressor (30). The high-pressure refrigerant is cooled by releasing heat to the outdoor air in the outdoor heat exchanger (44). The refrigerant radiated by the outdoor heat exchanger (44) flows through the heat source side line (38), the first connection line (51), and the expansion inflow line (48) in this order, and flows into the expander (31).

  In the expander (31), power is recovered as the refrigerant expands. The refrigerant that has passed through the expander (31) flows into the refrigerant storage tank (35) of the expansion / outflow line (49) and is separated into liquid refrigerant and gas refrigerant. The saturated liquid refrigerant in the refrigerant storage tank (35) flows out from the bottom and flows into the first flow path (46) of the internal heat exchanger (45). On the other hand, the saturated gas refrigerant in the refrigerant storage tank (35) flows out of the gas supply pipe (37) and is decompressed by the gas amount control valve (36), and then the second flow of the internal heat exchanger (45). It flows into the channel (47).

  In the internal heat exchanger (45), heat exchange is performed between the refrigerant in the first flow path (46) and the refrigerant in the second flow path (47). The refrigerant in the first flow path (46) is cooled by the refrigerant in the second flow path (47) and enters a supercooled state. On the other hand, the refrigerant in the second flow path (47) is heated by the refrigerant in the first flow path (46) and becomes overheated.

  The liquid refrigerant that has passed through the first flow path (46) flows in the order of the third connection line (61) and the use side line (39), and is distributed to each indoor circuit (11). Since the liquid refrigerant that has passed through the first flow path (46) is in a supercooled state, the pressure drops due to the pressure loss caused by the refrigerant piping before being distributed to each indoor circuit (11). It will not be in phase. For this reason, there is no drift in which the amount of liquid refrigerant is biased between the indoor circuits (11), and the liquid unit of an amount corresponding to the opening degree of the indoor control valve (53) is applied to all the indoor circuits (11). Phase refrigerant is supplied.

  The liquid refrigerant distributed to each indoor circuit (11) is decompressed by the indoor control valve (53) and then flows into the indoor heat exchanger (41). In the indoor heat exchanger (41), heat is exchanged between the refrigerant and the room air. By this heat exchange, the refrigerant absorbs heat from the room air and evaporates, while the room air is cooled and supplied to the room. The refrigerant evaporated in each indoor heat exchanger (41) joins in the second communication pipe (16) and flows into the outdoor circuit (14). The refrigerant that has flowed into the outdoor circuit (14) merges with the refrigerant that has been overheated in the second flow path (47), and is sucked into the compressor (30). The refrigerant sucked into the compressor (30) is compressed again and discharged.

  In this embodiment, the outdoor control valve (43) is disposed in the second connection line (52) where the refrigerant from the outdoor heat exchanger (44) toward the expander (31) does not flow. For this reason, the refrigerant that has dissipated heat in the outdoor heat exchanger (44) flows into the expander (31) without passing through the outdoor control valve (43). The power recovered by the expander (31) is not lost.

《Heating operation》
In the heating operation, the controller (65) sets the four-way switching valve (25) to the second state indicated by a broken line in FIG. In this state, when the controller (65) operates the compressor (30), the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, each indoor heat exchanger (41) functions as a radiator, and the outdoor heat exchanger (44) functions as an evaporator.

  The controller (65) during the heating operation adjusts the opening of the outdoor control valve (43) based on the measured value of the suction temperature sensor (23) and the measured value of the suction pressure sensor (27). By adjusting the opening of the outdoor control valve (43), the refrigerant flow rate of the outdoor heat exchanger (44) is adjusted so that the superheat degree of the refrigerant at the outlet of the outdoor heat exchanger (44) becomes a target value (for example, 5 ° C.). Adjusted. The opening of each indoor control valve (53) is adjusted based on the measured value of the indoor liquid temperature sensor (12) and the measured value of the indoor gas temperature sensor (13). By adjusting the opening of the indoor control valve (53), the refrigerant flow rate of the indoor heat exchanger (41) is adjusted so that the refrigerant temperature at the outlet of the indoor heat exchanger (41) becomes a target value.

  Specifically, the refrigerant having a pressure higher than the critical pressure is discharged from the compressor (30). This high-pressure refrigerant is distributed to each indoor circuit (11) through the second communication pipe (16). The refrigerant distributed to each indoor circuit (11) exchanges heat with indoor air in the indoor heat exchanger (41). By this heat exchange, the refrigerant dissipates heat to the room air and is cooled, while the room air is heated and supplied to the room. The refrigerant that has dissipated heat in each indoor heat exchanger (41) joins in the use side line (39) and flows into the outdoor circuit (14).

  The refrigerant flowing into the outdoor circuit (14) flows in the order of the fourth connection line (62) and the expansion inflow line (48), and flows into the expander (31). In the expander (31), power is recovered as the refrigerant expands. The refrigerant that has passed through the expander (31) flows into the refrigerant storage tank (35) of the expansion / outflow line (49) and is separated into liquid refrigerant and gas refrigerant. The liquid refrigerant in the refrigerant storage tank (35) flows out from the bottom, flows through the second connection line (52) and the heat source side line (38) in this order, and flows into the outdoor heat exchanger (44). At that time, in the second connection line (52), the refrigerant is depressurized when passing through the outdoor control valve (43).

  The refrigerant flowing into the outdoor heat exchanger (44) exchanges heat with the outdoor air. By this heat exchange, the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (44) is sucked into the compressor (30), compressed again, and discharged.

-Effect of the embodiment-
In the present embodiment, by providing the outdoor control valve (43) in the second connection line (52), the refrigerant radiated by the outdoor heat exchanger (44) during the cooling operation passes through the outdoor control valve (43). Instead, it flows into the expander (31). That is, the outdoor control valve (43) is disposed at a position other than the refrigerant flow path between the outdoor heat exchanger (44) and the expander (31) during the cooling operation. Therefore, the outdoor control valve (43) that adjusts the refrigerant flow rate of the outdoor heat exchanger (44) during the heating operation does not lose the power recovered by the expander (31) during the cooling operation. It is possible to prevent the operating efficiency of the air conditioner (20) from being lowered by the control valve (43).

  In this embodiment, the degree of superheat at the outlet of the evaporator (41, 44) is adjusted to an appropriate value (for example, 5 ° C.) by the outdoor control valve (43) or the indoor control valve (53). For this reason, liquid compression of the compressor (30) is prevented to improve the reliability of the air conditioner (20), and the heat exchange amount in the evaporator (41, 44) is secured to operate the air conditioner (20). Efficiency can be improved.

  Further, in the present embodiment, by using carbon dioxide as a refrigerant, the differential pressure of the refrigeration cycle can be increased as compared with other refrigerants. Therefore, the recovery power of the expander (31) can be increased, and the operating efficiency of the air conditioner (20) can be improved.

  Moreover, in this embodiment, the refrigerant | coolant storage tank (35) is provided in the expansion / outflow line (49), and after the refrigerant | coolant expanded by the expander (31) passes a refrigerant | coolant storage tank (35), outdoor adjustment It flows into the valve (43) or the indoor control valve (53). For this reason, whether the flow rate of refrigerant flowing out of the expander (31) is large or small relative to the opening of the outdoor control valve (43) or the indoor control valve (53), the outdoor control valve (43) or the refrigerant flow rate passing through the indoor control valve (53) is adjusted to a flow rate corresponding to the opening by the refrigerant storage tank (35).

  Further, in the present embodiment, by providing the gas supply pipe (37), the gas refrigerant having almost no cooling effect is returned from the refrigerant storage tank (35) to the suction side of the compressor (30). In addition, the enthalpy of the refrigerant sucked into the compressor (30) is increased by the gas refrigerant returned from the refrigerant storage tank (35). Therefore, the operating efficiency of the air conditioner (20) can be improved. Although such an effect cannot be obtained, the gas supply pipe (37) may be omitted in order to simplify the configuration of the refrigerant circuit (10).

-Modification of the embodiment-
A modification of the embodiment will be described. In this modification, as shown in FIG. 2, one outdoor unit (64) and one indoor unit (63) are provided. The third connection line (61) of the bridge circuit (24) is provided with a use side adjustment valve (53) instead of the second check valve (CV-2). The indoor circuit (11) is not provided with an indoor control valve.

  In this modified example, during the cooling operation, the refrigerant radiated by the outdoor heat exchanger (44) passes through the expander (31) and then evaporates through the use side control valve (53) of the third connection line (61). It flows into the indoor heat exchanger (41) that becomes the heat exchanger. The refrigerant flow rate of the indoor heat exchanger (41) is adjusted by the use side control valve (53) so that the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger (41) becomes a target value (for example, 5 ° C.).

  On the other hand, during the heating operation, the refrigerant radiated by the indoor heat exchanger (41) flows in the order of the use side line (39), the fourth connection line (62), and the expansion inflow line (48) to expand the expander (31 ). The refrigerant that has radiated heat in the indoor heat exchanger (41) flows into the expander (31) without passing through the use-side control valve (53). That is, the use side control valve (53) is disposed in the third connection line (61) in which the refrigerant from the indoor heat exchanger (41) to the expander (31) does not flow during the heating operation. Therefore, the power recovered by the expander (31) during heating operation is not lost due to the use-side control valve (53) that adjusts the refrigerant flow rate of the indoor heat exchanger (41) during cooling operation. It is possible to prevent the operating efficiency of the air conditioner (20) from being lowered by the use side control valve (53).

<< Other Embodiments >>
You may comprise the said embodiment like the following modifications.

-First modification-
About the said embodiment, as shown in FIG. 3, you may provide a bypass line (28) and a bypass amount adjustment valve (29) in a refrigerant circuit (10). The bypass line (28) connects the expansion / inflow line (48) and the expansion / outflow line (49). The bypass amount adjusting valve (29) is provided in the bypass line (28). The bypass amount adjusting valve (29) adjusts the refrigerant flow rate in the bypass line (28), that is, the refrigerant flow rate that bypasses the expander (31).

  In this first modification, by setting the bypass amount adjustment valve (29) to the open state during the cooling operation, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31). Enters the expansion / outflow line (49). On the other hand, even during the heating operation, by setting the bypass amount adjusting valve (29) to the open state, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31) and the expansion outflow line. Flows into (49). In the first modification, the refrigerant flow rate that bypasses the expander (31) is adjusted by the bypass line (28) and the bypass amount adjustment valve (29) in both the cooling operation and the heating operation. Therefore, it is possible to balance the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) in both the cooling operation and the heating operation, depending on the operating conditions such as the outside air temperature. Operation control becomes possible.

-Second modification-
About the said embodiment, a controller (65) may adjust the opening degree of an outdoor control valve (43) at the time of air_conditionaing | cooling operation. When the outdoor control valve (43) is set to the open state during the cooling operation, a part of the refrigerant that has passed through the heat source side line (38) flows into the second connection line (52), and the expansion / outflow line (49) It merges with the refrigerant that has passed through and goes to the indoor heat exchanger (41). That is, a part of the refrigerant that has passed through the heat source side line bypasses the expander (31) and goes to the indoor heat exchanger (41). The controller (65) constitutes bypass amount adjusting means (65).

  In the second modification, the second connection line (52) is used as a flow path for bypassing the expander (31) during the cooling operation. Therefore, the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) can be balanced without complicating the configuration of the refrigerant circuit (10).

  In addition, in the modification of the said embodiment, a controller (65) adjusts the opening degree of a utilization side control valve (53) at the time of heating operation, and is a 3rd connection line as a flow path which bypasses an expander (31). (61) may be used.

-Third modification-
About the said embodiment, as shown in FIG. 4, the non-return which prohibits the flow of the refrigerant | coolant which goes to the exit end of an expansion outflow line (49) from the other end of a heat-source side line (38) to a 2nd connection line (52). A valve (CV-4) may be provided.

  Here, when the check valve (CV-4) is not provided in the second connection line (52), the outdoor control valve (43) prevents the refrigerant from flowing through the second connection line (52) during the cooling operation. ) May be set to the fully closed state, the refrigerant may leak from the outdoor control valve (43). The refrigerant leaking from the outdoor control valve (43) merges with the refrigerant that has passed through the expansion / outflow line (49) and travels toward the indoor heat exchanger (41). That is, a part of the refrigerant passing through the heat source side line (38) unintentionally bypasses the expander (31), and the power recovered by the expander (31) decreases.

  On the other hand, in the third modification, the check valve (CV-4) can prevent the refrigerant from leaking from the outdoor control valve (43) during the cooling operation. Therefore, it is possible to prevent the power recovered by the expander (31) from being reduced unintentionally.

-Fourth modification-
About the said embodiment, as shown in FIG. 5, you may use a solenoid valve (SV) instead of a non-return valve (CV) in a bridge circuit (24).

-5th modification-
About the said embodiment, you may connect a gas supply pipe | tube (37) not to the suction side of a compressor (30) but to the compression chamber in the middle of a compression stroke.

-Sixth Modification-
About the said embodiment, you may comprise a compressor (30) by the low stage compression mechanism and the high stage compression mechanism. The low stage side compression mechanism and the high stage side compression mechanism are connected in series with each other. That is, the compressor (30) is configured to perform two-stage compression by the low-stage side compression mechanism and the high-stage side compression mechanism. In this case, the gas supply pipe (37) may be connected to the suction side of the high stage compression mechanism.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus in which an expander for power recovery is provided in a refrigerant circuit.

10 Refrigerant circuit 11 Indoor circuit (use side circuit)
14 Outdoor circuit (heat source side circuit)
20 Air conditioner (refrigeration equipment)
24 Bridge circuit (switching circuit)
28 Bypass line 29 Bypass amount control valve 30 Compressor 31 Expander 35 Refrigerant storage tank 38 Heat source side line 39 User side line 41 Indoor heat exchanger (user side heat exchanger)
43 Outdoor expansion valve (heat source side control valve)
44 Outdoor heat exchanger (heat source side heat exchanger)
48 Expansion Inflow Line 49 Expansion Outflow Line 51 First Heat Source Connection Line 52 Second Heat Source Connection Line 53 Indoor Control Valve (Utilization Side Control Valve)
61 1st use connection line 62 2nd use connection line 65 Controller (bypass amount adjusting means)

  The present invention relates to a refrigeration apparatus in which an expander for power recovery is provided in a refrigerant circuit.

  Conventionally, a refrigerating apparatus in which an expander for power recovery is provided in a refrigerant circuit is known. In this type of refrigeration apparatus, for example, a compressor and an expander are connected by a single drive shaft, and the power recovered by the expander is used to drive the compressor.

  FIG. 7 of Patent Document 1 discloses an air conditioner as this type of refrigeration apparatus. The air conditioner is configured such that the refrigerant radiated by the outdoor heat exchanger flows into the expander during the cooling operation, and the power accompanying the expansion of the refrigerant is recovered in the expander. Further, during the heating operation, the refrigerant radiated by the indoor heat exchanger flows into the expander, and the motive power accompanying the expansion of the refrigerant is recovered in the expander.

JP 2006-308207 A

  By the way, in the conventional refrigeration apparatus, a control valve is provided between the bridge circuit and the heat source side heat exchanger so that the refrigerant flow rate of the evaporator can be adjusted during the heating operation. However, during the cooling operation, the refrigerant radiated by the heat source side heat exchanger passes through the control valve before flowing into the expander. In the expansion valve, the pressure loss of the refrigerant becomes larger than that of the pipe even if the opening degree is set to be fully open. For this reason, there is a problem that the power recovered in the expander is lost by the control valve.

  The present invention has been made in view of such a point, and the purpose of the roller is that in the refrigeration apparatus in which the expander for power recovery is provided in the refrigerant circuit, the refrigerant radiated by the heat exchanger is transferred to the expander. The purpose is to prevent the power recovered by the expander from being lost by the control valve for adjusting the flow rate of the refrigerant when the heat exchanger becomes an evaporator until the heat exchanger flows.

  In the first invention, a compressor (30), an expander (31), a heat source side heat exchanger (44), and a use side heat exchanger (41) are connected to perform a refrigeration cycle by circulating a refrigerant. A cooling circuit comprising a refrigerant circuit (10), wherein the heat source side heat exchanger (44) serves as a radiator and the use side heat exchanger (41) serves as an evaporator, and the use side heat exchanger (41) A refrigeration apparatus (20) capable of selecting a heating operation in which the heat source side heat exchanger (44) becomes an evaporator becomes a target.

In the refrigeration apparatus (20), the refrigerant circuit (10) has one end connected to the liquid side of the heat source side heat exchanger (44) and one end connected to the use side. The utilization side line (39) connected to the liquid side of the heat exchanger (41), the expansion inlet line (48) whose outlet end is connected to the inlet side of the expander (31), and the inlet end of the expander ( 31) and an expansion / outflow line (49) connected to the outflow side of the refrigerant circuit (10), the expansion / inflow line (48) communicates with the heat source side line (38) and the refrigerant circuit (10) The expansion / outflow line (49) communicates with the use side line (39), the expansion / inflow line (48) communicates with the use side line (39), and the expansion / outflow line (49) communicates with the heat source side line. (38) and the switching circuit for switching between a state communicating (24) are provided, disposed in the expansion outflow line (49), One refrigerant temporarily storable refrigerant storage tank (35), a flow passage for connecting the switching circuit (24) to your Keru upper Symbol heat source side line (38) and the expansion outlet line (49) A heat source side control valve (43) provided in (52) for adjusting the refrigerant flow rate of the heat source side heat exchanger (44) during the heating operation, and the heat source side heat exchanger (44) during the heating operation. And a controller (65) that adjusts the opening degree of the heat source side control valve (43) so that the degree of superheat of the refrigerant at the outlet becomes a target value .

In 1st invention, the refrigerant | coolant thermally radiated with the utilization side heat exchanger (41) at the time of a heating operation connects an expansion outflow line (49) and a heat source side line (38) after passing an expander (31). It flows into the heat source side heat exchanger (44) serving as an evaporator through the refrigerant flow passage (52). The refrigerant flow rate of the heat source side heat exchanger (44) is adjusted by the heat source side adjustment valve (43) when passing through the refrigerant flow passage (52). On the other hand, during the cooling operation, the refrigerant dissipated in the heat source side heat exchanger (44) passes through the refrigerant flow path connecting the heat source side line (38) and the expansion inflow line (48) to the expander (31). Flow into. The refrigerant radiated by the heat source side heat exchanger (44) flows into the expander (31) without passing through the heat source side control valve (43). Further, the refrigerant expanded by the expander (31) flows into the heat source side control valve (43) after passing through the refrigerant storage tank (35). For this reason, even if the refrigerant flow rate flowing out of the expander (31) is large or small relative to the opening of the heat source side control valve (43), it passes through the heat source side control valve (43). The refrigerant flow rate to be adjusted is adjusted to a flow rate according to the opening degree by the refrigerant storage tank (35).

According to a second invention , in the first invention, the refrigerant connection line (62) connecting the user side line (39) and the expansion inflow line (48) includes the user side line during the heating operation. A check valve (CV-3) that allows only the refrigerant flow from (39) to the expansion inflow line (48) is provided.

According to a third invention, in the first or second invention, the degree of opening of the heat source side adjustment valve (43) is adjusted in order to adjust a refrigerant flow rate that bypasses the expander (31) during the cooling operation. Bypass amount adjusting means (65) is provided.

In the third invention, the opening degree of the heat source side adjustment valve (43) is adjusted by the bypass amount adjustment means (65) during the cooling operation. When the heat source side control valve (43) is set to the open state, a part of the refrigerant that has passed through the heat source side line (38) connects the expansion / outflow line (49) and the heat source side line (38). Into the flow passage (52), and merges with the refrigerant that has passed through the expansion / outflow line (49) and travels toward the use-side heat exchanger (41). That is, the refrigerant that has passed through the heat source side line (38) bypasses the expander (31) and travels to the use side heat exchanger (41). In the third aspect of the invention, the refrigerant flow rate that bypasses the expander (31) during the cooling operation is adjusted by the bypass amount adjusting means (65).

According to a fourth invention, in any one of the first to third inventions, a bypass line connecting the expansion inflow line (48) and the expansion outflow line (49) to the refrigerant circuit (10). (28) and a bypass amount adjusting valve (29) for adjusting the refrigerant flow rate in the bypass line (28) are provided.

In the fourth invention, by setting the bypass amount adjusting valve (29) to the open state during the cooling operation, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31). Then flows into the expansion / outflow line (49). On the other hand, even during the heating operation, by setting the bypass amount adjusting valve (29) to the open state, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31) and the expansion outflow line. Flows into (49). In the fourth aspect of the invention, the flow rate of the refrigerant that bypasses the expander (31) is adjusted by the bypass line (28) and the bypass amount adjustment valve (29) in both the cooling operation and the heating operation.

According to a fifth invention, in any one of the first to fourth inventions, the refrigerant circuit (10) has a heat source side circuit (14) provided with the heat source side heat exchanger (44). A plurality of use side circuits (11) each provided with the use side heat exchanger (41) are connected in parallel to each other.

In the fifth invention, the plurality of use side circuits (11) are connected in parallel to the heat source side circuit (14). In the refrigerant circuit (10), the refrigerant flowing out from the heat source side circuit (14) merges after passing through each use side circuit (11) and returns to the heat source side circuit (14).

In a sixth aspect based on any one of the first to fifth aspects, the refrigerant circuit (10) circulates the refrigerant so that the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

In the sixth invention, the high pressure of the refrigeration cycle performed in the refrigerant circuit (10) is set to a value higher than the critical pressure of the refrigerant. That is, the refrigerant discharged from the compressor (30) is in a supercritical state.

In each invention of the first乃 optimum sixth, by providing the heat-source-side control valve (43) in a flow passage connecting the heat source side line (38) and expansion outflow line (49) (52), the cooling operation Sometimes, the refrigerant radiated by the heat source side heat exchanger (44) flows into the expander (31) without passing through the heat source side control valve (43). That is, the heat source side control valve (43) is disposed at a position other than the refrigerant flow path between the heat source side heat exchanger (44) and the expander (31) during the cooling operation. Therefore, the power recovered by the expander (31) during the cooling operation is not lost due to the heat source side control valve (43) that adjusts the refrigerant flow rate of the heat source side heat exchanger (44) during the heating operation. Further, it is possible to prevent the operating efficiency of the refrigeration apparatus (20) from being lowered by the heat source side control valve (43) .

Also, in the third invention, the refrigerant flow which bypasses the expander (31) during the cooling operation is to be regulated by the bypass quantity adjusting means (65). Here, for example, when the compressor (30) and the expander (31) are connected by a single drive shaft, the expander (31) with respect to the refrigerant flow rate discharged by the compressor (30). In some cases, it is difficult to perform a desired refrigeration cycle because the refrigerant flow rate of the refrigerant is not balanced. In order to solve such a problem, it is conceivable to provide a pipe for bypassing the expander (31) in the refrigerant circuit (10). However, the configuration of the refrigerant circuit (10) is complicated accordingly. On the other hand, in the third aspect of the invention, the refrigerant flow passage (52) connecting the heat source side line (38) and the expansion / outflow line (49) is used as a flow path for bypassing the expander (31). ing. Therefore, the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) can be balanced without complicating the configuration of the refrigerant circuit (10).

In the fourth aspect of the invention, the flow rate of refrigerant bypassing the expander (31) is adjusted by the bypass line (28) and the bypass amount adjusting valve (29) in both the cooling operation and the heating operation. ing. Accordingly, it is possible to balance the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) in both the cooling operation and the heating operation.

It is a schematic block diagram of the air conditioning machine which concerns on embodiment. It is a schematic block diagram of the air conditioning machine which concerns on the modification of embodiment. It is a schematic block diagram of the air conditioning machine which concerns on the 1st modification of other embodiment. It is a schematic block diagram of the bridge circuit which concerns on a reference example . It is a schematic block diagram of the bridge circuit which concerns on the 3rd modification of other embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The present embodiment is an air conditioner (20) configured by a refrigeration apparatus according to the present invention. As shown in FIG. 1, the air conditioner (20) includes one outdoor unit (64) and three indoor units (63a, 63b, 63c). The number of indoor units (63) is merely an example. The air conditioner (20) is configured to be able to select a cooling operation that is a cooling operation and a heating operation that is a heating operation.

The air conditioner (20) of the present embodiment includes a refrigerant circuit (10) filled with carbon dioxide (CO ₂ ) as a refrigerant. In the refrigerant circuit (10), a refrigerant (CO ₂ ) is circulated to perform a vapor compression refrigeration cycle. In this refrigeration cycle, the high pressure of the refrigeration cycle is set to a value higher than the critical pressure of carbon dioxide.

  The refrigerant circuit (10) includes three indoor circuits (11a, 11b, 11c) that are use side circuits and one outdoor circuit (14) that is a heat source side circuit. These indoor circuits (11a, 11b, 11c) are connected in parallel to the outdoor circuit (14) by the first connecting pipe (15) and the second connecting pipe (16). Specifically, one end of the first communication pipe (15) is connected to the first shut-off valve (17) of the outdoor circuit (14), and the other end is branched into three to each indoor circuit (11a, 11b, 11c). ) Connected to the liquid side end. One end of the second communication pipe (16) is connected to the second shut-off valve (18) of the outdoor circuit (14), and the other end branches into three, and the gas side of each indoor circuit (11a, 11b, 11c) Connected to the end.

《Outdoor circuit configuration》
The outdoor circuit (14) is accommodated in the outdoor unit (64). The outdoor circuit (14) includes a compression / expansion unit (26), an outdoor heat exchanger (44), a refrigerant storage tank (35), an internal heat exchanger (45), a four-way switching valve (25), and a bridge circuit. (24) is provided. The bridge circuit (24) constitutes a switching circuit. The outdoor unit (64) is provided with an outdoor fan (not shown) for sending outdoor air to the outdoor heat exchanger (44).

  The compression / expansion unit (26) includes a casing (21) which is a vertically long and cylindrical sealed container. A compressor (30), an expander (31), and an electric motor (32) are accommodated in the casing (21). In the casing (21), the compressor (30), the electric motor (32), and the expander (31) are connected to each other by a single drive shaft.

Each of the compressor (30) and the expander (31) is constituted by a positive displacement fluid machine (such as a swinging piston type rotary fluid machine, a rolling piston type rotary fluid machine, and a scroll fluid machine). The compressor (30) compresses the sucked refrigerant (CO ₂ ) to the critical pressure or higher. The expander (31) expands the inflowing refrigerant (CO ₂ ) to recover power (expansion power). The compressor (30) is driven by both the power recovered by the expander (31) and the power obtained by energizing the electric motor (32). AC power is supplied to the electric motor (32) from an inverter not shown. The compressor (30) is configured to have a variable capacity by changing the frequency of the alternating current supplied to the electric motor (32). The compressor (30) and the expander (31) always rotate at the same rotational speed.

  The outlet end of the expansion inflow line (48) is connected to the inflow side of the expander (31). The inlet end of the expansion inflow line (48) is connected to the bridge circuit (24). The inlet end of the expansion / outflow line (49) is connected to the outflow side of the expander (31). The outlet end of the expansion / outflow line (49) is connected to the bridge circuit (24).

  The outdoor heat exchanger (44), which is a heat source side heat exchanger, is configured by a cross fin type fin-and-tube heat exchanger. Outdoor air is supplied to the outdoor heat exchanger (44) by an outdoor fan. In the outdoor heat exchanger (44), heat is exchanged between the outdoor air and the refrigerant. The gas side of the outdoor heat exchanger (44) is connected to the third port of the four-way switching valve (25). One end of a heat source side line (38) is connected to the liquid side of the outdoor heat exchanger (44). The other end of the heat source side line (38) is connected to the bridge circuit (24).

  The refrigerant storage tank (35) is a vertically long and cylindrical sealed container. The refrigerant storage tank (35) is provided in the expansion / outflow line (49). In the refrigerant storage tank (35), the refrigerant pipe extending from the expander (31) is connected to an upper position of the refrigerant storage tank (35). A refrigerant pipe extending to the bridge circuit (24) is connected to the bottom of the refrigerant storage tank (35). A gas supply pipe (37) connected to the suction side of the compressor (30) is connected to the top of the refrigerant storage tank (35). The gas supply pipe (37) is provided with a gas amount adjusting valve (36) constituted by an electronic expansion valve having a variable opening.

  In the refrigerant storage tank (35), the refrigerant flowing from the expander (31) is separated into liquid refrigerant and gas refrigerant. Among them, the liquid refrigerant flows into the bridge circuit (24) from the bottom of the refrigerant storage tank (35). The gas refrigerant flows out of the gas supply pipe (37) and is sucked into the compressor (30). In the refrigerant storage tank (35), the refrigerant from the expander (31) toward the bridge circuit (24) is temporarily stored.

  The internal heat exchanger (45) is provided across the gas supply pipe (37) and the expansion / outflow line (49). The internal heat exchanger (45) includes a first channel (46) installed downstream of the refrigerant storage tank (35) in the expansion / outflow line (49), and a first channel installed in the middle of the gas supply pipe (37). And two flow paths (47). In the internal heat exchanger (45), the first channel (46) and the second channel (47) are arranged adjacent to each other. In the internal heat exchanger (45), heat exchange is performed between the refrigerant in the first flow path (46) and the refrigerant in the second flow path (47).

  The bridge circuit (24) is a circuit in which the first connection line (51), the second connection line (52), the third connection line (61), and the fourth connection line (62) are connected in a bridge shape. The first connection line (51) connects the other end of the heat source side line (38) and the inlet end of the expansion inflow line (48). The second connection line (52) connects the other end of the heat source side line (38) and the outlet end of the expansion / outflow line (49). The third connection line (61) connects the other end of the use side line (39) and the outlet end of the expansion / outflow line (49). The fourth connection line (62) connects the other end of the use side line (39) and the inlet end of the expansion inflow line (48).

  In addition, in this embodiment, from the connection location of the 3rd connection line (61) and the 4th connection line (62) in a bridge circuit (24) to the indoor heat exchanger (41a, 41b, 41c) mentioned later Refrigerant piping constitutes the use side line (39). Specifically, the use side line (39) includes a refrigerant pipe between the bridge circuit (24) and the first closing valve (17), a first communication pipe (15), and each indoor circuit (11a, 11b, 11c). ) And a refrigerant pipe between the indoor heat exchanger (41a, 41b, 41c).

  The first connection line (51) is provided with a first check valve (CV-1) that prohibits the flow of refrigerant from the inlet end of the expansion inflow line (48) toward the other end of the heat source side line (38). ing. The second connection line (52) is provided with an outdoor control valve (43) that constitutes a heat source side control valve. The third connection line (61) is provided with a second check valve (CV-2) that prohibits the flow of refrigerant from the other end of the use side line (39) toward the outlet end of the expansion / outflow line (49). ing. The fourth connection line (62) is provided with a third check valve (CV-3) that prohibits the flow of refrigerant from the inlet end of the expansion inflow line (48) toward the other end of the use side line (39). ing.

  In the bridge circuit (24), the refrigerant that has passed through the outdoor heat exchanger (44) during the cooling operation is the heat source side line (38), the first connection line (51), the expansion inflow line (48), the expander (31), A cooling flow path is formed to flow in the order of the expansion / outflow line (49), the third connection line (61), and the use side line (39). Further, the bridge circuit (24) allows the refrigerant that has passed through each indoor heat exchanger (41) during heating operation to be used side line (39), fourth connection line (62), expansion inflow line (48), expander. (31), an expansion / outflow line (49), a second connection line (52), and a heat source side line (38) are formed in this order to form a heating flow path.

  The first port of the four-way switching valve (25) is connected to the suction side of the compressor (30). The second port is connected to the second closing valve (18). The third port is connected to the outdoor heat exchanger (44). The fourth port is connected to the discharge side of the compressor (30). The four-way selector valve (25) has a state in which the first port and the second port communicate with each other and the third port and the fourth port communicate with each other (a first state indicated by a solid line in FIG. 1); A state in which the first port and the third port communicate with each other and the second port and the fourth port communicate with each other (second state indicated by a broken line in FIG. 1) is configured to be switchable.

  In the outdoor circuit (14), a discharge temperature sensor (22) and a discharge pressure sensor (19) are provided on the discharge side of the compressor (30). A suction temperature sensor (23) and a suction pressure sensor (27) are provided on the suction side of the compressor (30).

《Indoor circuit configuration》
Each indoor circuit (11a, 11b, 11c) is accommodated in each indoor unit (63a, 63b, 63c). Each indoor circuit (11) has an indoor heat exchanger (41a, 41b, 41c) that is a use side heat exchanger and an indoor adjustment that is a use side control valve in order from the gas side end to the liquid side end. Valves (53a, 53b, 53c) are provided. Each indoor unit (63) is provided with an indoor fan for sending room air to each indoor heat exchanger (41) (not shown).

  The indoor heat exchanger (41) is configured by a cross fin type fin-and-tube heat exchanger. Indoor air is supplied to the indoor heat exchanger (41) by an indoor fan. In the indoor heat exchanger (41), heat is exchanged between the indoor air and the refrigerant. The indoor control valve (53) is an electronic expansion valve with a variable opening.

  In each indoor circuit (11), indoor liquid temperature sensors (12a, 12b, 12c) are provided on the liquid side of the indoor heat exchanger (41). Indoor gas temperature sensors (13a, 13b, 13c) are provided on the gas side of the indoor heat exchanger (41).

-Driving action-
The operation of the air conditioner (20) will be described. The air conditioner (20) is provided with a controller (65) for switching the four-way switching valve (33) and controlling the operation state.

《Cooling operation》
In the cooling operation, the controller (65) sets the four-way switching valve (25) to the first state shown by the solid line in FIG. In this state, when the controller (65) operates the compressor (30), the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, the outdoor heat exchanger (44) functions as a radiator, and each indoor heat exchanger (41) functions as an evaporator.

  The controller (65) during the cooling operation keeps the opening degree of the outdoor control valve (43) in a fully closed state. During the cooling operation, the opening degree of each indoor control valve (53) is adjusted based on the measured value of the indoor liquid temperature sensor (12) and the measured value of the indoor gas temperature sensor (13). Refrigerant flow rate of the indoor heat exchanger (41) so that the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger (41) becomes a target value (for example, 5 ° C) by adjusting the opening of the indoor control valve (53). Is adjusted.

  Specifically, the refrigerant having a pressure higher than the critical pressure is discharged from the compressor (30). The high-pressure refrigerant is cooled by releasing heat to the outdoor air in the outdoor heat exchanger (44). The refrigerant radiated by the outdoor heat exchanger (44) flows through the heat source side line (38), the first connection line (51), and the expansion inflow line (48) in this order, and flows into the expander (31).

  In the expander (31), power is recovered as the refrigerant expands. The refrigerant that has passed through the expander (31) flows into the refrigerant storage tank (35) of the expansion / outflow line (49) and is separated into liquid refrigerant and gas refrigerant. The saturated liquid refrigerant in the refrigerant storage tank (35) flows out from the bottom and flows into the first flow path (46) of the internal heat exchanger (45). On the other hand, the saturated gas refrigerant in the refrigerant storage tank (35) flows out of the gas supply pipe (37) and is decompressed by the gas amount control valve (36), and then the second flow of the internal heat exchanger (45). It flows into the channel (47).

  In the internal heat exchanger (45), heat exchange is performed between the refrigerant in the first flow path (46) and the refrigerant in the second flow path (47). The refrigerant in the first flow path (46) is cooled by the refrigerant in the second flow path (47) and enters a supercooled state. On the other hand, the refrigerant in the second flow path (47) is heated by the refrigerant in the first flow path (46) and becomes overheated.

  The liquid refrigerant that has passed through the first flow path (46) flows in the order of the third connection line (61) and the use side line (39), and is distributed to each indoor circuit (11). Since the liquid refrigerant that has passed through the first flow path (46) is in a supercooled state, the pressure drops due to the pressure loss caused by the refrigerant piping before being distributed to each indoor circuit (11). It will not be in phase. For this reason, there is no drift in which the amount of liquid refrigerant is biased between the indoor circuits (11), and the liquid unit of an amount corresponding to the opening degree of the indoor control valve (53) is applied to all the indoor circuits (11). Phase refrigerant is supplied.

  The liquid refrigerant distributed to each indoor circuit (11) is decompressed by the indoor control valve (53) and then flows into the indoor heat exchanger (41). In the indoor heat exchanger (41), heat is exchanged between the refrigerant and the room air. By this heat exchange, the refrigerant absorbs heat from the room air and evaporates, while the room air is cooled and supplied to the room. The refrigerant evaporated in each indoor heat exchanger (41) joins in the second communication pipe (16) and flows into the outdoor circuit (14). The refrigerant that has flowed into the outdoor circuit (14) merges with the refrigerant that has been overheated in the second flow path (47), and is sucked into the compressor (30). The refrigerant sucked into the compressor (30) is compressed again and discharged.

  In this embodiment, the outdoor control valve (43) is disposed in the second connection line (52) where the refrigerant from the outdoor heat exchanger (44) toward the expander (31) does not flow. For this reason, the refrigerant that has dissipated heat in the outdoor heat exchanger (44) flows into the expander (31) without passing through the outdoor control valve (43). The power recovered by the expander (31) is not lost.

《Heating operation》
In the heating operation, the controller (65) sets the four-way switching valve (25) to the second state indicated by a broken line in FIG. In this state, when the controller (65) operates the compressor (30), the refrigerant circulates in the refrigerant circuit (10) to perform a refrigeration cycle. At that time, each indoor heat exchanger (41) functions as a radiator, and the outdoor heat exchanger (44) functions as an evaporator.

  The controller (65) during the heating operation adjusts the opening of the outdoor control valve (43) based on the measured value of the suction temperature sensor (23) and the measured value of the suction pressure sensor (27). By adjusting the opening of the outdoor control valve (43), the refrigerant flow rate of the outdoor heat exchanger (44) is adjusted so that the superheat degree of the refrigerant at the outlet of the outdoor heat exchanger (44) becomes a target value (for example, 5 ° C.). Adjusted. The opening of each indoor control valve (53) is adjusted based on the measured value of the indoor liquid temperature sensor (12) and the measured value of the indoor gas temperature sensor (13). By adjusting the opening of the indoor control valve (53), the refrigerant flow rate of the indoor heat exchanger (41) is adjusted so that the refrigerant temperature at the outlet of the indoor heat exchanger (41) becomes a target value.

  Specifically, the refrigerant having a pressure higher than the critical pressure is discharged from the compressor (30). This high-pressure refrigerant is distributed to each indoor circuit (11) through the second communication pipe (16). The refrigerant distributed to each indoor circuit (11) exchanges heat with indoor air in the indoor heat exchanger (41). By this heat exchange, the refrigerant dissipates heat to the room air and is cooled, while the room air is heated and supplied to the room. The refrigerant that has dissipated heat in each indoor heat exchanger (41) joins in the use side line (39) and flows into the outdoor circuit (14).

  The refrigerant flowing into the outdoor circuit (14) flows in the order of the fourth connection line (62) and the expansion inflow line (48), and flows into the expander (31). In the expander (31), power is recovered as the refrigerant expands. The refrigerant that has passed through the expander (31) flows into the refrigerant storage tank (35) of the expansion / outflow line (49) and is separated into liquid refrigerant and gas refrigerant. The liquid refrigerant in the refrigerant storage tank (35) flows out from the bottom, flows through the second connection line (52) and the heat source side line (38) in this order, and flows into the outdoor heat exchanger (44). At that time, in the second connection line (52), the refrigerant is depressurized when passing through the outdoor control valve (43).

  The refrigerant flowing into the outdoor heat exchanger (44) exchanges heat with the outdoor air. By this heat exchange, the refrigerant absorbs heat from the outdoor air and evaporates. The refrigerant evaporated in the outdoor heat exchanger (44) is sucked into the compressor (30), compressed again, and discharged.

-Effect of the embodiment-
In the present embodiment, by providing the outdoor control valve (43) in the second connection line (52), the refrigerant radiated by the outdoor heat exchanger (44) during the cooling operation passes through the outdoor control valve (43). Instead, it flows into the expander (31). That is, the outdoor control valve (43) is disposed at a position other than the refrigerant flow path between the outdoor heat exchanger (44) and the expander (31) during the cooling operation. Therefore, the outdoor control valve (43) that adjusts the refrigerant flow rate of the outdoor heat exchanger (44) during the heating operation does not lose the power recovered by the expander (31) during the cooling operation. It is possible to prevent the operating efficiency of the air conditioner (20) from being lowered by the control valve (43).

  In this embodiment, the degree of superheat at the outlet of the evaporator (41, 44) is adjusted to an appropriate value (for example, 5 ° C.) by the outdoor control valve (43) or the indoor control valve (53). For this reason, liquid compression of the compressor (30) is prevented to improve the reliability of the air conditioner (20), and the heat exchange amount in the evaporator (41, 44) is secured to operate the air conditioner (20). Efficiency can be improved.

  Further, in the present embodiment, by using carbon dioxide as a refrigerant, the differential pressure of the refrigeration cycle can be increased as compared with other refrigerants. Therefore, the recovery power of the expander (31) can be increased, and the operating efficiency of the air conditioner (20) can be improved.

  Moreover, in this embodiment, the refrigerant | coolant storage tank (35) is provided in the expansion / outflow line (49), and after the refrigerant | coolant expanded by the expander (31) passes a refrigerant | coolant storage tank (35), outdoor adjustment It flows into the valve (43) or the indoor control valve (53). For this reason, whether the flow rate of refrigerant flowing out of the expander (31) is large or small relative to the opening of the outdoor control valve (43) or the indoor control valve (53), the outdoor control valve (43) or the refrigerant flow rate passing through the indoor control valve (53) is adjusted to a flow rate corresponding to the opening by the refrigerant storage tank (35).

  Further, in the present embodiment, by providing the gas supply pipe (37), the gas refrigerant having almost no cooling effect is returned from the refrigerant storage tank (35) to the suction side of the compressor (30). In addition, the enthalpy of the refrigerant sucked into the compressor (30) is increased by the gas refrigerant returned from the refrigerant storage tank (35). Therefore, the operating efficiency of the air conditioner (20) can be improved. Although such an effect cannot be obtained, the gas supply pipe (37) may be omitted in order to simplify the configuration of the refrigerant circuit (10).

-Modification of the embodiment-
A modification of the embodiment will be described. In this modification, as shown in FIG. 2, one outdoor unit (64) and one indoor unit (63) are provided. The third connection line (61) of the bridge circuit (24) is provided with a use side adjustment valve (53) instead of the second check valve (CV-2). The indoor circuit (11) is not provided with an indoor control valve.

  In this modified example, during the cooling operation, the refrigerant radiated by the outdoor heat exchanger (44) passes through the expander (31) and then evaporates through the use side control valve (53) of the third connection line (61). It flows into the indoor heat exchanger (41) that becomes the heat exchanger. The refrigerant flow rate of the indoor heat exchanger (41) is adjusted by the use side control valve (53) so that the degree of superheat of the refrigerant at the outlet of the indoor heat exchanger (41) becomes a target value (for example, 5 ° C.).

  On the other hand, during the heating operation, the refrigerant radiated by the indoor heat exchanger (41) flows in the order of the use side line (39), the fourth connection line (62), and the expansion inflow line (48) to expand the expander (31 ). The refrigerant that has radiated heat in the indoor heat exchanger (41) flows into the expander (31) without passing through the use-side control valve (53). That is, the use side control valve (53) is disposed in the third connection line (61) in which the refrigerant from the indoor heat exchanger (41) to the expander (31) does not flow during the heating operation. Therefore, the power recovered by the expander (31) during heating operation is not lost due to the use-side control valve (53) that adjusts the refrigerant flow rate of the indoor heat exchanger (41) during cooling operation. It is possible to prevent the operating efficiency of the air conditioner (20) from being lowered by the use side control valve (53).

<< Other Embodiments >>
You may comprise the said embodiment like the following modifications.

-First modification-
About the said embodiment, as shown in FIG. 3, you may provide a bypass line (28) and a bypass amount adjustment valve (29) in a refrigerant circuit (10). The bypass line (28) connects the expansion / inflow line (48) and the expansion / outflow line (49). The bypass amount adjusting valve (29) is provided in the bypass line (28). The bypass amount adjusting valve (29) adjusts the refrigerant flow rate in the bypass line (28), that is, the refrigerant flow rate that bypasses the expander (31).

  In this first modification, by setting the bypass amount adjustment valve (29) to the open state during the cooling operation, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31). Enters the expansion / outflow line (49). On the other hand, even during the heating operation, by setting the bypass amount adjusting valve (29) to the open state, a part of the refrigerant flowing through the expansion inflow line (48) bypasses the expander (31) and the expansion outflow line. Flows into (49). In the first modification, the refrigerant flow rate that bypasses the expander (31) is adjusted by the bypass line (28) and the bypass amount adjustment valve (29) in both the cooling operation and the heating operation. Therefore, it is possible to balance the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) in both the cooling operation and the heating operation, depending on the operating conditions such as the outside air temperature. Operation control becomes possible.

-Second modification-
About the said embodiment, a controller (65) may adjust the opening degree of an outdoor control valve (43) at the time of air_conditionaing | cooling operation. When the outdoor control valve (43) is set to the open state during the cooling operation, a part of the refrigerant that has passed through the heat source side line (38) flows into the second connection line (52), and the expansion / outflow line (49) It merges with the refrigerant that has passed through and goes to the indoor heat exchanger (41). That is, a part of the refrigerant that has passed through the heat source side line bypasses the expander (31) and goes to the indoor heat exchanger (41). The controller (65) constitutes bypass amount adjusting means (65).

  In the second modification, the second connection line (52) is used as a flow path for bypassing the expander (31) during the cooling operation. Therefore, the refrigerant flow rate discharged from the compressor (30) and the refrigerant flow rate sucked by the expander (31) can be balanced without complicating the configuration of the refrigerant circuit (10).

  In addition, in the modification of the said embodiment, a controller (65) adjusts the opening degree of a utilization side control valve (53) at the time of heating operation, and is a 3rd connection line as a flow path which bypasses an expander (31). (61) may be used.

-Reference example-
As a reference example, as shown in FIG. 4, a check valve that prohibits the flow of refrigerant from the other end of the heat source side line (38) to the outlet end of the expansion / outflow line (49) in the second connection line (52). (CV-4) may be provided.

  Here, when the check valve (CV-4) is not provided in the second connection line (52), the outdoor control valve (43) prevents the refrigerant from flowing through the second connection line (52) during the cooling operation. ) May be set to the fully closed state, the refrigerant may leak from the outdoor control valve (43). The refrigerant leaking from the outdoor control valve (43) merges with the refrigerant that has passed through the expansion / outflow line (49) and travels toward the indoor heat exchanger (41). That is, a part of the refrigerant passing through the heat source side line (38) unintentionally bypasses the expander (31), and the power recovered by the expander (31) decreases.

In contrast, in this reference example , the check valve (CV-4) can prevent the refrigerant from leaking from the outdoor control valve (43) during the cooling operation. Therefore, it is possible to prevent the power recovered by the expander (31) from being reduced unintentionally.

- Third modification -
About the said embodiment, as shown in FIG. 5, you may use a solenoid valve (SV) instead of a non-return valve (CV) in a bridge circuit (24).

- Fourth Modified Example -
About the said embodiment, you may connect a gas supply pipe | tube (37) not to the suction side of a compressor (30) but to the compression chamber in the middle of a compression stroke.

- Fifth Modification -
About the said embodiment, you may comprise a compressor (30) by the low stage compression mechanism and the high stage compression mechanism. The low stage side compression mechanism and the high stage side compression mechanism are connected in series with each other. That is, the compressor (30) is configured to perform two-stage compression by the low-stage side compression mechanism and the high-stage side compression mechanism. In this case, the gas supply pipe (37) may be connected to the suction side of the high stage compression mechanism.

  In addition, the above embodiment is an essentially preferable illustration, Comprising: It does not intend restrict | limiting the range of this invention, its application thing, or its use.

  As described above, the present invention is useful for a refrigeration apparatus in which an expander for power recovery is provided in a refrigerant circuit.

10 Refrigerant circuit 11 Indoor circuit (use side circuit)
14 Outdoor circuit (heat source side circuit)
20 Air conditioner (refrigeration equipment)
24 Bridge circuit (switching circuit)
28 Bypass line 29 Bypass amount control valve 30 Compressor 31 Expander 35 Refrigerant storage tank 38 Heat source side line 39 User side line 41 Indoor heat exchanger (user side heat exchanger)
43 Outdoor expansion valve (heat source side control valve)
44 Outdoor heat exchanger (heat source side heat exchanger)
48 Expansion Inflow Line 49 Expansion Outflow Line 51 First Heat Source Connection Line 52 Second Heat Source Connection Line 53 Indoor Control Valve (Utilization Side Control Valve)
61 1st use connection line 62 2nd use connection line 65 Controller (bypass amount adjusting means)

Claims (8)

The compressor (30), the expander (31), the heat source side heat exchanger (44), and the use side heat exchanger (41) are connected, and a refrigerant circuit (10) that circulates the refrigerant and performs a refrigeration cycle is provided. Prepared,
Cooling operation in which the heat source side heat exchanger (44) serves as a radiator and the use side heat exchanger (41) serves as an evaporator, and the use side heat exchanger (41) serves as a radiator and the heat source A refrigeration apparatus in which the side heat exchanger (44) can select a heating operation as an evaporator,
The refrigerant circuit (10) has one end connected to the liquid side of the heat source side heat exchanger (44) and one end connected to the liquid side of the use side heat exchanger (41). Connected use side line (39), expansion inflow line (48) with outlet end connected to inflow side of expander (31), and expansion with inlet end connected to outflow side of expander (31) While an outflow line (49) is formed,
The refrigerant circuit (10) includes a state in which the expansion inflow line (48) communicates with the heat source side line (38) and the expansion outflow line (49) communicates with the utilization side line (39); A switching circuit (24) is provided for switching between a state where the inflow line (48) communicates with the use side line (39) and the expansion / outflow line (49) communicates with the heat source side line (38);
In the switching circuit (24), the refrigerant flow passage (52) connecting the expansion / outflow line (49) and the heat source side line (38) has a heat source side heat exchanger (44) during the heating operation. A refrigeration apparatus comprising a heat source side control valve (43) for adjusting a refrigerant flow rate of the refrigerant. The compressor (30), the expander (31), the heat source side heat exchanger (44), and the use side heat exchanger (41) are connected, and a refrigerant circuit (10) that circulates the refrigerant and performs a refrigeration cycle is provided. Prepared,
Cooling operation in which the heat source side heat exchanger (44) serves as a radiator and the use side heat exchanger (41) serves as an evaporator, and the use side heat exchanger (41) serves as a radiator and the heat source A refrigeration apparatus in which the side heat exchanger (44) can select a heating operation as an evaporator,
The refrigerant circuit (10) has one end connected to the liquid side of the heat source side heat exchanger (44) and one end connected to the liquid side of the use side heat exchanger (41). Connected use side line (39), expansion inflow line (48) with outlet end connected to inflow side of expander (31), and expansion with inlet end connected to outflow side of expander (31) While an outflow line (49) is formed,
The refrigerant circuit (10) includes a state in which the expansion inflow line (48) communicates with the heat source side line (38) and the expansion outflow line (49) communicates with the utilization side line (39); A switching circuit (24) is provided for switching between a state where the inflow line (48) communicates with the use side line (39) and the expansion / outflow line (49) communicates with the heat source side line (38);
In the switching circuit (24), the refrigerant flow passage (61) connecting the utilization side line (39) and the expansion / outflow line (49) has a utilization side heat exchanger (41) during the cooling operation. A refrigeration apparatus comprising a use-side control valve (53) for adjusting a refrigerant flow rate of the refrigerant. In claim 1,
In the switching circuit (24), the flow of the refrigerant from the heat source side line (38) to the expansion / outflow line (49) is caused to flow into the refrigerant flow passage (52) provided with the heat source side control valve (43). A refrigeration apparatus provided with a check valve (CV-4) to be prohibited. In claim 1,
In order to adjust the flow rate of the refrigerant that bypasses the expander (31) during the cooling operation, it is provided with a bypass amount adjusting means (65) that adjusts the opening of the heat source side adjusting valve (43). Refrigeration equipment. In any one of Claims 1 thru | or 4,
The refrigerating apparatus, wherein the expansion / outflow line (49) is provided with a refrigerant storage tank (35) capable of temporarily storing the refrigerant. In any one of claims 1 to 5,
The refrigerant circuit (10) includes a bypass line (28) connecting the expansion / inflow line (48) and the expansion / outflow line (49), and a bypass amount adjustment for adjusting a refrigerant flow rate in the bypass line (28). A refrigeration apparatus comprising a valve (29). In any one of Claims 1 thru | or 6,
The refrigerant circuit (10) has a plurality of usages each provided with the use side heat exchanger (41) with respect to the heat source side circuit (14) provided with the heat source side heat exchanger (44). The freezing apparatus characterized by the side circuit (11) being mutually connected in parallel. In any one of Claims 1 thru | or 7,
In the refrigerant circuit (10), the refrigerant is circulated so that the high pressure of the refrigeration cycle is higher than the critical pressure of the refrigerant.

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