JP2010236706A - Air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve air conditioning performance while reducing pressure loss of gas side communicating piping during cooling operation as much as possible in an air conditioner with a refrigerant circuit with a heat source side circuit and a use side circuit connected by the liquid side and gas side communicating piping. <P>SOLUTION: To an outdoor circuit (11), an ejector (25) expanding a refrigerant that has flowed out from an outdoor heat exchanger (23) during the cooling operation or a refrigerant that has flowed out from an indoor heat exchanger (26) during warming operation, a gas-liquid separator (27) separating the refrigerant in the refrigerant circuit (10) into gas and liquid, a gas side flow-out passage (7b) introducing the gas refrigerant after being subjected to gas-liquid separation by the gas-liquid separator (27) to a suction port of a compressor (21), and a liquid side flow-out passage (7c) introducing the liquid refrigerant after being subjected to the gas-liquid separation by the gas-liquid separator (27) to the suction port of the ejector (25), are connected. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an air conditioner having a refrigerant circuit in which a heat source side circuit and a use side circuit are connected by a communication pipe.

  Conventionally, a separate type air conditioner including an outdoor unit and an indoor unit is known. This air conditioner can perform indoor air conditioning operation by installing the outdoor unit outdoors and installing the indoor unit indoors (see, for example, Patent Document 1).

Specifically, the outdoor unit is provided with an outdoor circuit, and the indoor unit is provided with an indoor circuit. A compressor, a four-way switching valve, an outdoor heat exchanger, and an expansion valve are connected to the outdoor circuit. An indoor heat exchanger is connected to the indoor circuit. The outdoor circuit and the indoor circuit are connected by a gas side communication pipe and a liquid side communication pipe to form a refrigerant circuit that performs a vapor compression refrigeration cycle. This refrigerant circuit is configured so that the refrigerant circulation direction can be reversed by the switching operation of the four-way switching valve. When the circulation direction of the refrigerant circuit is switched to the forward direction by the four-way switching valve, the outdoor heat exchanger becomes a condenser and the indoor heat exchanger becomes an evaporator, and a cooling operation is performed. On the other hand, when the circulation direction of the refrigerant circuit is switched in the reverse direction by the four-way switching valve, the outdoor heat exchanger becomes an evaporator and the indoor heat exchanger becomes a condenser to perform heating operation.
JP-A-11-344275

  By the way, in the conventional air conditioner, during the cooling operation, the low-pressure gas refrigerant evaporated in the indoor heat exchanger is sucked into the compressor through the gas communication pipe. On the other hand, during heating operation, the high-pressure gas refrigerant discharged from the compressor dissipates heat in the indoor heat exchanger via the gas connection pipe.

  In this case, when the pressure loss of the refrigerant gas flowing through the gas communication pipe is compared between the cooling operation and the heating operation, the density of the low-pressure gas refrigerant is larger than the density of the high-pressure gas refrigerant, so the flow rate of the refrigerant is There is a problem that the pressure loss becomes larger during the cooling operation.

  Further, during cooling operation, dryout may occur near the refrigerant outlet of the indoor heat exchanger. That is, in the vicinity of the refrigerant outlet of the heat exchanger, the refrigerant flow state may become a spray flow, and in that case, the inner peripheral surface near the refrigerant outlet of the heat exchanger is dried, and the atomized refrigerant evaporates. It becomes difficult. For this reason, when this dry out occurs, there is a problem that the performance during cooling operation is degraded.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a cooling operation in an air conditioner having a refrigerant circuit in which a heat source side circuit and a use side circuit are connected by liquid side and gas side communication pipes. The pressure loss of the gas side communication pipe at the time is reduced as much as possible, and the dry-out of the use side heat exchanger during the cooling operation is suppressed to improve the air conditioning performance.

  In the first invention, a heat source side circuit (11) having a compressor (21) and a heat source side heat exchanger (23) and a use side circuit (12) having a use side heat exchanger (26) are connected to each other. (4, 5) and a refrigerant circuit (10) for performing a vapor compression refrigeration cycle. A heat source side heat exchanger (23) is connected to the discharge side of the compressor (21) and the compression circuit A cooling state in which the use side heat exchanger (26) is connected to the suction side of the compressor (21), and the use side heat exchanger (26) is connected to the discharge side of the compressor (21) and the compressor The precondition is an air conditioner that can be switched to a heating state in which the heat source side heat exchanger (23) is connected to the suction side of (21).

  In the heat source side circuit (11) of the air conditioner, the refrigerant that has flowed out of the heat source side heat exchanger (23) during the cooling state or the refrigerant that has flowed out of the use side heat exchanger (26) during the heating state Gas-liquid separation was performed by an ejector (25) to be expanded, a gas-liquid separator (27) for gas-liquid separation of the refrigerant in the refrigerant circuit (10) after the evaporation process of the refrigeration cycle, and the gas-liquid separator (27). After the gas refrigerant is separated by the gas side outflow passage (7b) for guiding the latter gas refrigerant to the suction port of the compressor (21) and the gas-liquid separator (27), the ejector (25) sucks the liquid refrigerant. The liquid side outflow passage (7c) leading to the mouth is connected.

  In the first invention, a gas-liquid separator (27) is connected to the suction side of the compressor (21). In this way, even if the refrigerant flows out from the use side heat exchanger (26) in a two-phase state, the two-phase state refrigerant is gas-liquid separated by the liquid separator (27), and the gas refrigerant Only the compressor (21) can be inhaled.

  An ejector (25) is connected to the liquid side outflow passage (7c) of the gas-liquid separator (27). In this way, the liquid refrigerant of the gas-liquid separator (27) can be returned from the ejector (25) to the use side heat exchanger (26), and the use side heat exchanger (26) corresponding to the amount of the liquid refrigerant. It becomes possible to increase the flow rate of the refrigerant flowing through.

  According to a second invention, in the first invention, the refrigerant circuit (10) includes the heat source side heat exchanger (23) connected to the inlet side of the ejector (25) and the ejector in the cooling state. A first state in which the use side heat exchanger (26) is connected to the outlet side of (25), and the use side heat exchanger (26) is connected to the inlet side of the ejector (25) in the heating state. And a switching mechanism (24) capable of switching to a second state in which the heat source side heat exchanger (23) is connected to the outlet side of the ejector (25).

  Here, since the flow direction of the refrigerant in the refrigerant circuit is reversed between the cooling state and the heating state, generally, in either the cooling state or the heating state, from the inlet side of the ejector (25), the ejector (25) It becomes impossible to make a refrigerant flow in.

  In the second aspect of the invention, the refrigerant can be allowed to flow into the ejector (25) from the inlet side of the ejector (25) in either the cooling state or the heating state.

  A third invention is the refrigerant according to the first or second invention, wherein the refrigerant has passed through the heat source side heat exchanger (23) in the cooling state or has passed through the use side heat exchanger (26) in the heating state. And a heat exchanger (31) for exchanging heat between the refrigerant flowing through the gas side outflow passage (7b).

  For example, when the cooling load increases rapidly in the cooling state, a large amount of two-phase refrigerant may temporarily flow into the gas-liquid separator (27). In this case, the liquid refrigerant that could not be gas-liquid separated by the gas-liquid separator (27) is sucked into the compressor (21) through the gas-side outflow passage (7b), which is not preferable.

  In the third invention, even in such a case, the gas side outflow passage (with the refrigerant that has passed through the heat source side heat exchanger (23) or the refrigerant that has passed through the use side heat exchanger (26) in the heating state ( It becomes possible to heat the two-phase refrigerant flowing through 7b).

  According to a fourth invention, in any one of the first to third inventions, the refrigerating machine oil that is formed at the bottom of the gas-liquid separator (27) and is discharged together with the refrigerant from the compressor (21). It is characterized by having a storage part (28) for storing, and an oil return passage (35) communicating the storage part (28) and the gas side outflow passage (7b).

  In 4th invention, the refrigerating machine oil collected in the storage part (28) of the said gas-liquid separator (27) can be returned to the said compressor (21) through the said oil return channel | path (35). When carbon dioxide is used as the refrigerant, PAG is generally used as the refrigerating machine oil for the carbon dioxide. This PAG has a higher specific gravity than carbon dioxide. Therefore, when PAG flows into the gas-liquid separator (27) together with carbon dioxide, the PAG accumulates at the bottom of the reservoir (28) in the gas-liquid separator (27). In the present invention, the refrigerating machine oil collected at the bottom of the reservoir (28) can be returned to the compressor (21).

  According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the liquid side outflow passage (7c) contains refrigerant flowing from the gas-liquid separator (27) side toward the ejector (25) side. A check valve (29) is provided in a direction that allows the flow and prohibits the flow of the refrigerant in the reverse direction.

  For example, if the amount of refrigerant circulation in the refrigerant circuit (10) decreases, the suction force of the ejector (25) weakens, and it becomes difficult to sufficiently suck the liquid refrigerant in the gas-liquid separator (27). The pressure on the suction side of the ejector (25) is higher than the pressure on the liquid outflow side of the gas-liquid separator (27), and the refrigerant is transferred from the ejector (25) to the gas-liquid separator (27). It may flow backward.

  In the fifth aspect of the invention, the check valve (29) is provided in the liquid side outflow passage (7c), so that the air flow from the ejector (25) can be reduced even when the refrigerant circulation amount of the refrigerant circuit (10) is small. The refrigerant no longer flows back to the liquid separator (27).

  According to a sixth invention, in any one of the first to fifth inventions, the ejector (25) includes an adjusting means (25a) capable of adjusting an expansion amount of the refrigerant passing through the ejector (25). It is characterized by being attached.

  In the sixth aspect of the invention, the ejector (25) can also serve as an expansion valve whose opening degree can be adjusted.

  According to a seventh invention, in any one of the first to sixth inventions, the refrigerant circuit (10) flows through the bypass passage (40) bypassing the ejector (25) and the bypass passage (40). The first flow rate changing means (41) for changing the flow rate of the refrigerant is provided.

  For example, if the flow resistance of the ejector (25) is too large, the refrigerant in the refrigerant circuit (10) may not be circulated sufficiently.

  In the seventh invention, in such a case, the refrigerant in the refrigerant circuit (10) can be sufficiently circulated by flowing the refrigerant through the bypass passage (40). Further, the flow rate of the refrigerant flowing through the bypass passage (40) can be adjusted.

  According to an eighth invention, in any one of the first to seventh inventions, the refrigerant flowing from the heat source side heat exchanger (23) to the ejector (25) in the cooling state or the use side heat exchange in the heating state. The second flow rate changing means (42) for changing the flow rate of the refrigerant flowing from the vessel (26) to the ejector (25) is provided.

  In the eighth invention, the flow rate of the refrigerant passing through the ejector (25) can be adjusted by adjusting the second flow rate changing means (42).

  According to a ninth invention, in any one of the first to eighth inventions, the refrigerant circulating in the refrigerant circuit (10) is carbon dioxide.

  Here, in the conventional air conditioner, when carbon dioxide is used as the refrigerant of the refrigerant circuit (10), when the use side heat exchanger (26) is used as an evaporator, In the vicinity of the refrigerant outlet of the use side heat exchanger (26), the refrigerant gradually becomes an atomized flow from the annular flow, and therefore, a dryout in which the inner peripheral surface of the heat transfer tube becomes dry is likely to occur.

  In the ninth aspect of the invention, since the refrigerant can flow out from the use side heat exchanger (26) in a two-phase state, for example, by adjusting the expansion amount of the ejector (25), the use side heat exchanger can be adjusted. It is possible to set the degree of dryness of the outlet refrigerant in (26) to be low so that dryout does not occur near the refrigerant outlet of the use side heat exchanger (26).

  A tenth invention is characterized in that, in any one of the first to eighth inventions, the refrigerant circulating in the refrigerant circuit (10) has a saturation pressure of 0.4 MPa or less at an evaporation temperature of 0 ° C. . Examples of the refrigerant include HFC134a and HFO1234yf.

  In the tenth aspect of the invention, since the refrigerant can flow out from the use side heat exchanger (26) in a two-phase state, for example, by adjusting the expansion amount of the ejector (25), the use side heat exchanger can be adjusted. By setting the dryness of the outlet refrigerant in (26) low, the density can be increased, the flow velocity can be lowered, and the pressure loss in the communication pipe (4) can be suppressed as much as possible.

  According to the present invention, in the cooling state, the two-phase refrigerant can flow from the use side circuit (12) to the heat source side circuit (11) through the communication pipe (4). Thereby, the pressure loss of the said connection piping (4) can be reduced rather than before.

  Of the two-phase refrigerant that has flowed into the heat source side circuit (11), only the liquid refrigerant can be returned to the use side heat exchanger (26). The flow rate of the refrigerant flowing through the exchanger (26) can be increased. As the refrigerant flow rate increases, the flow rate of the refrigerant flowing through the use side heat exchanger (26) increases, and the heat exchange performance of the use side heat exchanger (26) can be improved. Thereby, the air-conditioning performance of the air conditioner can be improved as compared with the conventional art. Moreover, the dry-out of the use side heat exchanger (26) during the cooling operation can be suppressed, and the air conditioning performance can be improved.

  Further, according to the second invention, the refrigerant can be caused to flow into the ejector (25) from the inlet side of the ejector (25) in both the cooling state and the heating state. Thereby, liquid refrigerant can be sucked from the gas-liquid separator (27) in either the cooling state or the heating state.

  Further, according to the third aspect of the invention, for example, even when the cooling load suddenly increases in the cooling state and the liquid refrigerant flows into the gas side outflow passage (7b), the liquid refrigerant is reduced. It can heat with the said heat exchanger (31). Thus, after the refrigerant flowing through the gas side outflow passage (7b) is overheated, the refrigerant can be sucked into the compressor (21), and the compressor (21) is reliably prevented from being wet. Can do.

  According to the fourth aspect of the invention, the refrigeration oil accumulated in the storage part (28) of the gas-liquid separator (27) can be returned to the compressor (21) through the oil return passage (35). . Thereby, it is possible to prevent a shortage of refrigerating machine oil in the compressor (21).

  According to the fifth aspect of the invention, for example, even if the refrigerant circulation amount in the refrigerant circuit (10) decreases, the refrigerant does not flow backward from the ejector (25) to the gas-liquid separator (27). Thereby, even when the refrigerant circulation amount of the refrigerant circuit (10) is small, the air conditioner can be stably operated.

  According to the sixth aspect of the invention, since the ejector (25) also serves as an expansion valve whose opening degree can be adjusted, there is no need to separately provide an expansion valve in the refrigerant circuit (10), and the refrigerant circuit (10 ) Can be simplified.

  Further, according to the seventh invention, for example, when the flow resistance of the ejector (25) is large and the circulation amount of the refrigerant in the refrigerant circuit (10) cannot be increased, the ejector (25) By bypassing a part of the refrigerant flowing in, the refrigerant circulation amount of the refrigerant circuit (10) can be increased. Thereby, it is possible to prevent the maximum capacity of the air conditioner from being limited by the flow resistance of the ejector (25).

  In this case, it is also possible to adjust the capacity of the air conditioner by adjusting the flow rate of the refrigerant within the adjustment range of the first flow rate changing means (41).

  According to the eighth aspect of the present invention, when the adjusting means (25a) is not attached to the ejector (25), the second flow rate changing means (42) passes the ejector (25). The flow rate of the refrigerant can be adjusted.

  When the adjusting means (25a) is attached to the ejector (25), the flow rate of the refrigerant passing through the ejector (25) can be adjusted regardless of the adjusting means (25a). . Thereby, the flow rate of the refrigerant can be adjusted stepwise by the ejector (25) and the second flow rate changing means (42).

  According to the ninth aspect of the present invention, even when carbon dioxide is used as the refrigerant in the refrigerant circuit (10), the dryness of the refrigerant flowing out from the use side heat exchanger (26) is lowered. By setting, it is possible to prevent dryout from occurring near the refrigerant outlet of the use side heat exchanger (26). Thereby, even if carbon dioxide is used as the refrigerant of the air conditioner of the present invention, the air conditioning performance of the air conditioner can be prevented from being reduced as much as possible.

  According to the tenth aspect of the invention, as the refrigerant of the refrigerant circuit (10), the saturation pressure with respect to the evaporation temperature of 0 ° C. is 0.4 MPa or less, the saturation pressure is relatively low, and the evaporation temperature drop due to pressure loss. Even if a refrigerant that greatly affects the air-conditioning performance of the air conditioner is used due to the large air quality, the above communication can be established by setting the dryness of the refrigerant flowing out of the use side heat exchanger (26) low. The pressure loss of the piping (4) can be suppressed as much as possible.

  Thereby, even when the refrigerant | coolant whose saturation pressure with respect to 0 degreeC of evaporation temperature is 0.4 Mpa or less is used as a refrigerant | coolant of the air conditioning apparatus of this invention, it can prevent the air conditioning performance of an air conditioning apparatus as much as possible.

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

  FIG. 1 shows a refrigerant circuit diagram in the air conditioning apparatus of the present embodiment. The air conditioner (1) of this embodiment is a separate type that includes an outdoor unit (2) and an indoor unit (3). The outdoor unit (2) is provided with an outdoor circuit (11), and the indoor unit (3) is provided with an indoor circuit (12). The first end (4a) of the outdoor circuit (11) and the first end (4b) of the indoor circuit (12) are connected by a first connection pipe (connection pipe) (4), and the outdoor circuit ( The second end (5a) of 11) and the second end (5b) of the indoor circuit (12) are connected by the second connecting pipe (connecting pipe) (5), so that a vapor compression refrigeration cycle is achieved. The refrigerant circuit (10) to perform is comprised. The refrigerant circuit (10) contains carbon dioxide as a refrigerant. Moreover, PAG is enclosed as refrigerating machine oil.

  The outdoor circuit (11) includes a compressor (21), a four-way switching valve (22), an outdoor heat exchanger (23), a check valve bridge circuit (24), an ejector (25), and a gas-liquid separator. (27) is connected. An indoor heat exchanger (26) is connected to the indoor circuit (12).

  The four-way selector valve (22) has four ports, a first state in which the first port and the fourth port communicate with each other and the second port and the third port communicate with each other (a state indicated by a solid line in FIG. 1). And a second state (state indicated by a broken line in FIG. 1) 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.

  The check valve bridge circuit (switching mechanism) (24) includes first to fourth check valves (CV1, CV2, CV3, CV4), and the first, second, third, and fourth check valves. The check valves (CV1, CV2, CV3, CV4) are connected in the order of closed circuit.

  The first check valve (CV1) is attached in such a direction as to permit the flow of refrigerant from the fourth check valve (CV4) side toward the second check valve (CV2) side. The second check valve (CV2) is attached in a direction that allows the flow of refrigerant from the first check valve (CV1) side toward the third check valve (CV3) side. The third check valve (CV3) is attached in a direction that allows the flow of refrigerant from the fourth check valve (CV4) side toward the second check valve (CV2) side. The fourth check valve (CV4) is attached in a direction that allows the flow of the refrigerant from the first check valve (CV1) side toward the third check valve (CV3) side.

  The compressor (21) is a hermetically sealed type, and has a variable capacity by an inverter (not shown) electrically connected to the compressor (21). The compressor (21) is configured to compress the sucked refrigerant to a predetermined pressure and discharge it. A first port of the four-way switching valve (22) is connected to the discharge side of the compressor (21), and the fourth port of the four-way switching valve (22) is one end of the outdoor heat exchanger (23). It is connected to the.

  The outdoor heat exchanger (23) constitutes an air heat exchanger in which heat is exchanged between refrigerant and outdoor air taken in by an outdoor fan (not shown) provided in the vicinity of the outdoor heat exchanger (23). Yes. The other end of the outdoor heat exchanger (23) is connected between the third and fourth check valves (CV3, CV4) in the check valve bridge circuit (24). The refrigerant pipe extending from between the third and second check valves (CV3, CV2) in the check valve bridge circuit (24) is connected to the inlet of the ejector (25).

  The ejector (25) has a driving flow path, a suction passage, and an ejection flow path (not shown). The driving refrigerant flowing in from the inlet of the ejector (25) is expanded by a nozzle provided in the driving channel when passing through the driving channel. The nozzle hole diameter is variable. Due to this expansion, the flow of the refrigerant is accelerated at the outlet of the nozzle, and the negative pressure generated by this acceleration sucks the suction refrigerant from the suction port of the ejector (25) into the suction passage, and flows through the suction passage. And the refrigerant | coolant which passed the said drive flow path and the refrigerant | coolant which passed the said suction flow path are mixed, and it flows in into the said ejection flow path. The refrigerant that has flowed into the ejection channel is decelerated and pressurized by a diffuser provided in the ejection channel, and then ejected from the ejection port of the ejector (25).

  The refrigerant pipe extending from the ejection port of the ejector (25) is connected between the first and fourth check valves (CV3, CV4) in the check valve bridge circuit (24). The refrigerant pipe extending from between the first and second check valves (CV3, CV2) in the check valve bridge circuit (24) is connected to the second end (5a) of the outdoor circuit (11). ing.

  As described above, the second end (5a) of the outdoor circuit (11) is connected to the second end (5b) of the indoor circuit (12) via the second connection pipe (5). A refrigerant pipe extending from the second end (5b) is connected to one end of the indoor heat exchanger (26).

  The indoor heat exchanger (26) constitutes an air heat exchanger in which heat is exchanged between the outdoor air taken in by an indoor fan (not shown) provided near the indoor heat exchanger (26) and the refrigerant. Yes. The refrigerant pipe extending from the other end of the indoor heat exchanger (26) is connected to the first end (4b) of the indoor circuit (12).

  As described above, the first end (4b) of the indoor circuit (12) is connected to the first end (4a) of the outdoor circuit (11) via the first connection pipe (4). The refrigerant pipe extending from the first end (4a) is connected to the third port of the four-way switching valve (22). An inflow pipe (7a) extending from the second port of the four-way switching valve (22) is connected to an inlet provided in the gas-liquid separator (27).

  The gas-liquid separator (27) is a closed container formed in a vertically long cylindrical shape, and the closed container is provided with a liquid outlet and a gas outlet in addition to the above-described inlet. Yes. Then, the refrigerant flowing in from the refrigerant inlet is gas-liquid separated in the container, and among the liquid refrigerant and gas refrigerant after the gas-liquid separation, the liquid refrigerant is caused to flow out from the liquid outlet, and the gas refrigerant is discharged from the gas It is comprised so that it can be made to flow out from an outflow port.

  A liquid side outflow pipe (liquid side outflow passage) (7c) extending from the liquid outflow port of the gas-liquid separator (27) is connected to the suction port of the ejector (25). The liquid side outflow pipe is provided with a check valve (29), which checks the flow of refrigerant from the gas-liquid separator (27) to the ejector (25). It is attached in a direction that permits and prohibits the flow of refrigerant in the reverse direction. A gas side outflow pipe (gas side outflow passage) (7b) extending from the gas outflow port of the gas-liquid separator (27) is connected to the suction side of the compressor (21).

-Driving action-
<Cooling operation>
Next, the operation of the air conditioner (1) will be described. First, after describing the cooling operation, the heating operation will be described.

  During the cooling operation, the four-way selector valve (22) is set to the first state. When the compressor (21) is started in this state, the outdoor heat exchanger (23) becomes a radiator and the indoor heat exchanger (26) becomes an evaporator to perform a cooling cycle.

  Specifically, the refrigerant compressed by the compressor (21) is discharged from the compressor (21) and then flows to the outdoor heat exchanger (23) through the four-way switching valve (22). The refrigerant that has flowed into the outdoor heat exchanger (23) radiates heat to the outdoor air, then flows out of the outdoor heat exchanger (23), and flows into the ejector (25) through the check valve bridge circuit (24).

  In the ejector (25), the refrigerant flowing from the check valve bridge circuit (24) flows through the drive passage, and the refrigerant is depressurized and accelerated by the nozzle of the drive passage. Due to the negative pressure generated by the acceleration of the refrigerant, the liquid refrigerant in the gas-liquid separator (27) is sucked into the suction passage of the ejector (25). Then, after the refrigerant in the drive passage and the liquid refrigerant in the suction passage are mixed in the ejection passage of the ejector (25), the pressure is reduced by the diffuser in the ejection passage and the pressure is increased. The pressurized refrigerant flows out of the ejection passage, and flows out of the outdoor circuit (11) through the check valve bridge circuit (24).

  The refrigerant that has flowed out of the outdoor circuit (11) flows into the indoor circuit (12) through the second connection pipe (5). The refrigerant flowing into the indoor circuit (12) flows into the indoor heat exchanger (26). In the indoor heat exchanger (26), the refrigerant absorbs heat from the indoor air and evaporates, and then flows out from the indoor heat exchanger (26). At this time, the indoor air is cooled by removing heat from the refrigerant, and the cooled indoor air is supplied into the room.

  On the other hand, the refrigerant in the indoor heat exchanger (26) does not flow out of the indoor heat exchanger (26) in a completely evaporated state, but flows out in a two-phase state. The refrigerant in the two-phase state flows out of the indoor circuit (12) and flows into the outdoor circuit (11) through the first connection pipe (4).

  The two-phase refrigerant flowing into the outdoor circuit (11) flows into the gas-liquid separator (27) through the four-way switching valve (22). In the gas-liquid separator (27), the two-phase refrigerant is separated into a liquid refrigerant and a gas refrigerant, and the liquid refrigerant is sucked into the ejector (25) as described above. On the other hand, the gas refrigerant is sucked into the compressor (21), compressed, and then discharged from the compressor (21). After being discharged from the compressor (21), it flows again to the outdoor heat exchanger (23) through the four-way switching valve (22). As the refrigerant circulates in this manner, the cooling operation of the air conditioner is performed.

<Heating operation>
During the heating operation, the four-way selector valve (22) is set to the second state. When the compressor (21) is started in this state, the outdoor heat exchanger (23) serves as an evaporator, and each indoor heat exchanger (26) serves as a radiator to perform a heating cycle.

  Specifically, the refrigerant compressed by the compressor (21) is discharged from the compressor (21). The refrigerant discharged from the compressor (21) flows out of the outdoor circuit (11) after passing through the four-way switching valve (22). The refrigerant that has flowed out of the outdoor circuit (11) flows into the indoor circuit (12) through the first connection pipe (4).

  The refrigerant that has flowed into the indoor circuit (12) flows to the indoor heat exchanger (26), radiates heat to the indoor air in the indoor heat exchanger (26), and then flows out of the indoor heat exchanger (26). . At this time, the indoor air is heated by the refrigerant, and the heated indoor air is supplied into the room. The refrigerant that has flowed out of the indoor heat exchanger (26) flows out of the indoor circuit (12), and flows into the outdoor circuit (11) through the second connection pipe (5).

  The refrigerant that has flowed into the outdoor circuit (11) flows into the ejector (25) through the check valve bridge circuit (24). In the ejector (25), the refrigerant flowing from the check valve bridge circuit (24) flows through the drive passage, and the refrigerant is depressurized and accelerated by the nozzle of the drive passage. Due to the negative pressure generated by the acceleration of the refrigerant, the liquid refrigerant in the gas-liquid separator (27) is sucked into the suction passage of the ejector (25). Then, after the refrigerant in the drive passage and the liquid refrigerant in the suction passage are mixed in the ejection passage of the ejector (25), the pressure is reduced by the diffuser in the ejection passage and the pressure is increased. The pressurized refrigerant flows out from the ejection passage.

  The refrigerant flowing out from the ejection passage of the ejector (25) flows into the outdoor heat exchanger (23) through the check valve bridge circuit (24), and from the outdoor air in the outdoor heat exchanger (23). After absorbing heat and evaporating, it flows out of the outdoor heat exchanger (23). The refrigerant that has flowed out of the outdoor heat exchanger (23) flows into the gas-liquid separator (27) through the four-way switching valve (22).

  The refrigerant flowing into the gas-liquid separator (27) is separated into liquid refrigerant and gas refrigerant in the gas-liquid separator (27), and the liquid refrigerant is sucked into the ejector (25) as described above. On the other hand, the gas refrigerant is sucked into the compressor (21), compressed, and then discharged from the compressor (21). After being discharged from the compressor (21), it flows again to the indoor heat exchanger (26) through the four-way switching valve (22). Thus, the refrigerant | coolant circulates and the heating operation of an air conditioning apparatus is performed.

-Effect of the embodiment-
According to this embodiment, during the cooling operation, the two-phase refrigerant can flow from the indoor circuit (12) to the outdoor circuit (11) through the first communication pipe (4). Thereby, the pressure loss of the refrigerant | coolant in the said 1st connection piping (4) can be reduced rather than before.

  Further, only the liquid refrigerant out of the two-phase refrigerant flowing into the outdoor circuit (11) can be returned to the indoor heat exchanger (26), and the indoor heat exchanger ( 26) The flow rate of the refrigerant flowing through can be increased. As the refrigerant flow rate increases, the flow rate of the refrigerant flowing through the indoor heat exchanger (26) increases, and the heat exchange performance of the indoor heat exchanger (26) can be improved. Thereby, the air-conditioning performance of the air conditioner can be improved as compared with the conventional art.

  Further, according to the present embodiment, by providing a check valve bridge circuit (24) in the refrigerant circuit (10), the inlet side of the ejector (25) can be used in both the cooling operation and the heating operation. The refrigerant can flow into the ejector (25).

  Moreover, according to this embodiment, the said ejector (25) is comprised so that adjustment of the expansion | swelling amount of the refrigerant | coolant which passes the inside of this ejector (25) is possible. Thereby, since the ejector (25) also serves as an expansion valve whose opening degree can be adjusted, there is no need to separately provide an expansion valve in the refrigerant circuit (10), and the configuration of the refrigerant circuit (10) is simplified. Can do.

  Further, according to the present embodiment, for example, even if the refrigerant circulation amount of the refrigerant circuit (10) decreases and the suction force of the ejector (25) decreases, the liquid side outflow passage (7c) By providing the check valve (29), it is possible to prevent the refrigerant from flowing backward from the ejector (25) to the gas-liquid separator (27). Thereby, even when the refrigerant circulation amount of the refrigerant circuit (10) is small, the air conditioner can be stably operated.

  Further, according to this embodiment, even when carbon dioxide is used as the refrigerant in the refrigerant circuit (10), dryout does not occur in the vicinity of the refrigerant outlet of the indoor heat exchanger (26). The dryness of the refrigerant flowing out of the indoor heat exchanger (26) can be set low. Thereby, even when carbon dioxide is used as the refrigerant of the air conditioner of the present embodiment, the air conditioning performance can be prevented from being reduced as much as possible.

  Next, modified examples 1 to 3 of the embodiment will be described. In these modified examples, the same parts as those in the refrigerant circuit of the air-conditioning apparatus according to Embodiment 1 are denoted by the same reference numerals, and only different points will be described.

-Modification 1 of embodiment-
FIG. 2 is a refrigerant circuit diagram of an air-conditioning apparatus according to Modification 1 of the embodiment. The difference between the refrigerant circuit of Modification 1 and the refrigerant circuit shown in the above embodiment is that a heat exchanger (31) for heating the refrigerant sucked into the compressor (21) is provided. is there.

  The heat exchanger (31) has a high temperature side flow path (32a) and a low temperature side flow path (32b), and the high temperature side flow path (32a) includes the check valve bridge circuit (24) and an ejector. (25) is connected to the refrigerant piping. On the other hand, the low temperature side channel (32b) of the heat exchanger (31) is connected to the gas side outflow pipe (7b) connecting the suction side of the compressor (21) and the gas-liquid separator (27). Has been.

  In this way, the refrigerant that flows through the gas side outflow passage (7b) with the refrigerant that has passed through the heat source side heat exchanger (23) in the cooling state or the refrigerant that has passed through the use side heat exchanger (26) in the heating state. Can be heated. Thus, after the refrigerant flowing through the gas side outflow passage (7b) is overheated, the refrigerant can be sucked into the compressor (21), and the compressor (21) is reliably prevented from being wet. Can do.

-Modification 2 of embodiment-
FIG. 3 is a refrigerant circuit diagram of an air-conditioning apparatus according to Modification 2 of the embodiment. The difference between the refrigerant circuit of Modification 2 and the refrigerant circuit shown in the above embodiment is that an oil reservoir (reservoir) (28) and an oil reservoir (28) are formed at the bottom of the gas-liquid separator (27). 28) and an oil return pipe (35) that communicates the gas side outflow pipe (7b) (oil return passage). In Modification 2, the oil return pipe (35) is connected to the upstream side of the heat exchanger (31) in the gas side outflow pipe (7b), but the heat exchanger (31) It may be connected to the downstream side.

  As a result, PAG having a specific gravity greater than that of carbon dioxide stays at the bottom of the storage section (28) in the gas-liquid separator (27), so that the stored PAG is compressed through the oil return passage (35). It will be possible to return to the machine (21). Thereby, it is possible to prevent a shortage of refrigerating machine oil in the compressor (21).

—Modification 3 of Embodiment—
FIG. 4 is a refrigerant circuit diagram of an air-conditioning apparatus according to Modification 3 of the embodiment. The difference between the refrigerant circuit of Modification 3 and the refrigerant circuit shown in the above embodiment is that a bypass pipe (bypass passage) (40) for bypassing the ejector (25) is provided. The bypass pipe (40) is provided with a flow rate adjusting valve (first flow rate changing means) (41).

  In this case, for example, when the flow resistance of the ejector (25) is too large to sufficiently circulate the refrigerant in the refrigerant circuit (10), the refrigerant is caused to flow into the bypass passage (40). Thus, the refrigerant circulation amount of the refrigerant circuit (10) can be increased.

  Thereby, it is possible to prevent the maximum capacity of the air conditioner from being limited by the flow resistance of the ejector (25). Moreover, the capacity | capacitance of the said air conditioning apparatus can also be adjusted by adjusting the flow volume of the refrigerant | coolant which flows through the said bypass channel (40). In Modification 3, the bypass pipe (40) is provided with a flow rate adjustment valve (41), but an electromagnetic valve is provided in place of the flow rate adjustment valve (41) to open and close the bypass passage (40). You may let them.

<< Other Embodiments >>
About the said embodiment, it is good also as the following structures.

  In this embodiment, carbon dioxide is used as the refrigerant. However, the present invention is not limited to this. For example, a refrigerant such as HFC134a or HFO1234yf, that is, a refrigerant having a saturation pressure with respect to an evaporation temperature of 0 ° C. of 0.4 MPa or less may be used. . In this case, the dryness of the refrigerant flowing out from the use side heat exchanger (26) is adjusted to be low. By doing so, the pressure loss of the first communication pipe (4) can be suppressed as much as possible, and the air conditioning performance of the air conditioner can be prevented from being reduced as much as possible.

  In the third modification of the embodiment, the hole diameter of the nozzle of the ejector (25) is variable. However, the present invention is not limited to this, and the hole diameter of the nozzle may be fixed. In this case, as shown in FIG. 5, an electromagnetic valve (42) or a flow rate adjusting valve (42) as a flow rate changing means is provided upstream of the ejector (25) so that it passes through the ejector (25). The amount of expansion of the refrigerant passing through the ejector (25) can be changed by adjusting the flow rate of the refrigerant.

  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 an air conditioner having a refrigerant circuit in which a heat source side circuit and a use side circuit are connected by a communication pipe.

It is a refrigerant circuit figure of the air harmony device concerning the embodiment of the present invention. It is a refrigerant circuit figure of the air harmony device concerning modification 1 of an embodiment of the present invention. It is a refrigerant circuit figure of the air conditioning apparatus which concerns on the modification 2 of embodiment of this invention. It is a refrigerant circuit figure of the air conditioning apparatus which concerns on the modification 3 of embodiment of this invention. It is a refrigerant circuit figure of the air harmony device concerning other embodiments.

1 Air conditioner
10 Refrigerant circuit
11 Outdoor circuit (heat source side circuit)
12 Indoor circuit (use side circuit)
21 Compressor
22 Four-way selector valve
23 Outdoor heat exchanger (heat source side heat exchanger)
24 Check valve bridge circuit (switching mechanism)
25 Ejector
26 Indoor heat exchanger (use side heat exchanger)
27 Gas-liquid separator
29 Check valve

Claims (10)

The heat source side circuit (11) having the compressor (21) and the heat source side heat exchanger (23) and the user side circuit (12) having the user side heat exchanger (26) are connected to the communication pipe (4, 5). A refrigerant circuit (10) connected to perform a vapor compression refrigeration cycle, a heat source side heat exchanger (23) connected to the discharge side of the compressor (21), and suction of the compressor (21) A cooling state where the use side heat exchanger (26) is connected to the side, and a use side heat exchanger (26) is connected to the discharge side of the compressor (21) and the suction side of the compressor (21) An air conditioner switchable to a heating state to which the heat source side heat exchanger (23) is connected,
The heat source side circuit (11) includes an ejector (25) for expanding the refrigerant that has flowed out of the heat source side heat exchanger (23) in the cooling state or the refrigerant that has flowed out of the use side heat exchanger (26) in the heating state. When,
A gas-liquid separator (27) for gas-liquid separation of the refrigerant in the refrigerant circuit (10) after the evaporation step of the refrigeration cycle;
A gas-side outflow passage (7b) for guiding the gas refrigerant after gas-liquid separation by the gas-liquid separator (27) to the suction port of the compressor (21);
An air conditioner characterized by being connected to a liquid-side outflow passage (7c) that guides the liquid refrigerant after gas-liquid separation by the gas-liquid separator (27) to the suction port of the ejector (25). In claim 1,
In the cooling circuit (10), the heat source side heat exchanger (23) is connected to the inlet side of the ejector (25) and the use side heat exchange is connected to the outlet side of the ejector (25) in the cooling state. And the use side heat exchanger (26) is connected to the inlet side of the ejector (25) and the outlet side of the ejector (25) is connected to the first state where the heat exchanger (26) is connected. An air conditioner characterized in that a switching mechanism (24) capable of switching to a second state to which the heat source side heat exchanger (23) is connected is connected. In claim 1 or 2,
The refrigerant that has passed through the heat source side heat exchanger (23) in the cooling state or the refrigerant that has passed through the use side heat exchanger (26) in the heating state and the refrigerant that flows through the gas side outflow passage (7b) are heated. An air conditioner provided with a heat exchanger (31) to be replaced. In any one of Claims 1-3,
A reservoir (28) for storing refrigerating machine oil formed at the bottom of the gas-liquid separator (27) and discharged together with the refrigerant from the compressor (21);
An air conditioner comprising an oil return passage (35) communicating the storage portion (28) and the gas side outflow passage (7b). In any one of Claims 1-4,
The liquid-side outflow passage (7c) is non-returned in a direction that allows refrigerant flow from the gas-liquid separator (27) side to the ejector (25) side and prohibits refrigerant flow in the reverse direction. An air conditioner provided with a valve (29). In any one of claims 1 to 5,
The air conditioner characterized in that an adjusting means (25a) capable of adjusting the expansion amount of the refrigerant passing through the ejector (25) is attached to the ejector (25). In any one of Claims 1-6,
The refrigerant circuit (10) is provided with a bypass passage (40) for bypassing the ejector (25), and first flow rate changing means (41) for changing the flow rate of the refrigerant flowing through the bypass passage (40). An air conditioner characterized by comprising: In any one of Claims 1-7,
Secondly, the flow rate of the refrigerant flowing from the heat source side heat exchanger (23) to the ejector (25) during the cooling state or the refrigerant flowing from the use side heat exchanger (26) to the ejector (25) during the heating state is changed. An air conditioner characterized in that a flow rate changing means (42) is provided. In any one of claims 1 to 8,
The air conditioner characterized in that the refrigerant circulating in the refrigerant circuit (10) is carbon dioxide. In any one of claims 1 to 8,
A refrigerant circulating through the refrigerant circuit (10) has a saturation pressure with respect to an evaporation temperature of 0 ° C of 0.4 MPa or less.

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